JP7621785B2 - MOTOR CONTROL DEVICE, OPTICAL DEVICE, AND ROBOT MANIPULATOR DEVICE - Google Patents

Description

The present invention relates to a motor control device that performs position feedback control of a motor.

By detecting the actual rotational position of the motor and performing position feedback control to adjust the drive voltage applied to the motor based on the deviation between the actual rotational position and the target rotational position (target trajectory), the actual rotational position of the motor can be controlled to follow the target trajectory.

Optical devices such as digital cameras and interchangeable lenses are equipped with optical units, such as a shutter unit and an aperture unit, that are driven by a motor. Patent Document 1 discloses a focal plane shutter unit in which the motor is rotated in the forward direction to move the shutter blades from an initial position to an exposure end position via a drive lever, and then the motor is rotated in the reverse direction to return the shutter blades to their initial positions. In this shutter unit, the shutter blades are driven between the initial position and the exposure end position with only one rotation of the motor.

JP 2015-7723 A

However, when position feedback control of a motor is performed during a small number of rotations, if the initial position deviation, which is the difference between the actual rotation position at the start of the control and the target trajectory, is large, oscillation occurs in the drive voltage of the motor to be controlled, making it difficult to match the actual rotation position of the motor with the target trajectory. In particular, in a focal plane shutter unit, if the actual rotation position of the motor (actual travel trajectory of the shutter blades) deviates from the target trajectory (target travel trajectory of the shutter blades), uneven exposure occurs. Furthermore, oscillation of the motor drive voltage causes a decrease in the accuracy of the stop rotation position of the motor.

These issues are not limited to optical units, but can be said to be similar to those in applications where motor position feedback control is performed at high speeds and low rotation speeds.

The present invention provides a motor control device that can absorb initial position deviations and achieve good controllability when performing position feedback control of a motor, as well as an optical device and a robot manipulator device that use the same.

A motor control device according to one aspect of the present invention includes a detection means for detecting an actual rotational position of a motor, a control means for performing position feedback control on the motor so that the detected actual rotational position moves sequentially toward a plurality of target rotational positions when the motor is rotated in one direction, and a processing means for performing processing for keeping an initial position deviation, which is a difference between the actual rotational position and a first target rotational position among the plurality of target rotational positions, within a predetermined range before starting the position feedback control, the processing means performing a processing for rotating the motor in one direction or in a reverse direction so that the actual rotational position approaches or coincides with the first target rotational position, and the processing means changes at least a part of the target rotational positions including the first target rotational position among the plurality of target rotational positions according to the rotation direction of the motor in the processing. The processing means also performs a processing for changing the first target rotational position in one direction or in the reverse direction so that the first target rotational position approaches or coincides with the actual rotational position. The processing means further selects the processing from a first processing for rotating the motor in one direction or in the reverse direction so that the actual rotational position approaches or coincides with the first target rotational position and a second processing for changing the first target rotational position in one direction or in the reverse direction so that the actual rotational position approaches or coincides with the actual rotational position. An optical device or a robot manipulator device including the motor control device also constitutes another aspect of the present invention.

A motor control method according to another aspect of the present invention includes a step of detecting an actual rotational position of a motor, a step of performing position feedback control on the motor so that the detected actual rotational position moves sequentially toward a plurality of target rotational positions when the motor is rotated in one direction, and a step of performing processing before starting the position feedback control to keep an initial position deviation, which is a difference between the actual rotational position and a first target rotational position among the plurality of target rotational positions, within a predetermined range, the step of performing processing to keep within the predetermined range includes a processing of rotating the motor in one direction or in a reverse direction so that the actual rotational position approaches or matches the first target rotational position, and the step of performing processing to keep within the predetermined range includes a processing of changing at least a part of the target rotational positions including the first target rotational position among the plurality of target rotational positions according to the rotation direction of the motor in the processing. The processing is also characterized in that the processing includes a processing of changing the first target rotational position in one direction or in the reverse direction so that the first target rotational position approaches or matches the actual rotational position. The processing is further characterized in that the processing is selected from a first processing of rotating the motor in one direction or in the reverse direction so that the actual rotational position approaches or matches the first target rotational position, and a second processing of changing the first target rotational position in one direction or in the reverse direction so that the actual rotational position approaches or matches the actual rotational position. A computer program for causing a computer to execute processing according to the above control method also constitutes another aspect of the present invention.

According to the present invention, when performing position feedback control of a motor, the initial position deviation can be absorbed, thereby achieving good controllability.

FIG. 1 is a block diagram showing a configuration of a motor control device according to a first embodiment. FIG. 2 is a block diagram showing a detailed configuration of the motor control device according to the first embodiment. FIG. 2 is a diagram illustrating the configuration of a motor and a position detection sensor according to the first embodiment. 5 is a flowchart showing a process performed by a position ENC circuit and a drive waveform generating circuit in the first embodiment. 5 is a diagram showing the relationship between a position detection sensor signal and a detected position count in the first embodiment. FIG. FIG. 4 is a diagram showing the relationship between a drive waveform and an electrical angle in the first embodiment. 3A and 3B are diagrams illustrating an example of the structure of a driven object in the first embodiment. FIG. 4 is a diagram showing target rotational position information in the first embodiment. FIG. 4 is a diagram showing the relationship between the initial position deviation and controllability in the first embodiment. 4 is a flowchart showing the processing performed in the first and second embodiments. 13A and 13B are diagrams illustrating update of target rotational position information in the second embodiment. FIG. 4 is a diagram showing the configuration of a focal plane shutter unit using a motor controlled by the motor control device of the first and second embodiments. FIG. 1 is a diagram showing the configuration of a digital camera equipped with the focal plane shutter unit of the first and second embodiments. FIG. 11 is a diagram showing the configuration of a robot manipulator apparatus according to a third embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

In Example 1, we will explain using a motor control device and a focal plane shutter unit as the optical unit.

Figure 1 shows a schematic configuration of a motor control device according to a first embodiment of the present invention. The motor control device performs position feedback control on the motor 11 so that the actual rotational position of the motor 11 (hereinafter referred to as the actual rotational position) moves sequentially toward a number of preset target rotational positions.

Various types of motors can be used as the motor 11 as long as they convert electricity into rotational motion. More specifically, they include brushless DC motors, brushless DC motors, and stepping motors. In this embodiment, a stepping motor is used, which allows for highly accurate rotational positioning.

The motor control device has a rotational position detection unit (detection means) 12, a drive waveform generation unit 13, a voltage gain setting unit 14, a target rotational position holding unit 15, a control unit 16, and an initial position deviation adjustment unit (processing means) 17. The drive waveform generation unit 13, the voltage gain setting unit 14, the target rotational position holding unit 15, and the control unit 16 constitute the control means.

The rotational position detection unit 12 detects the rotational position of the motor 11. For example, an optical encoder consisting of an optical scale with a light-dark pattern and an optical sensor that receives light emitted from a light-emitting unit and reflected or transmitted by the optical scale can be used as a position detection sensor. Alternatively, a magnetic encoder consisting of a magnetic scale with a magnetic pattern and a magnetoresistance element (MR sensor) that detects changes in magnetism from the magnetic scale can be used. These sensors can be used to directly detect the rotational angle of the motor shaft, or the position of a driven member driven by the motor can be detected and converted into the rotational angle of the motor shaft.

The drive waveform generating unit 13 generates a waveform of the drive voltage (hereinafter referred to as the drive waveform) to be applied to the motor 11. The voltage gain setting unit 14 sets a voltage gain value for the drive waveform.

The target rotational position holding unit 15 holds information on the above-mentioned multiple target rotational positions (hereinafter, also referred to as target rotational position information). The control unit 16 determines an output control amount using a position deviation, which is a difference between the actual rotational position of the motor 11 detected by the rotational position detection unit 12 and the target rotational position at the time of detection, as an input, and allocates the output control amount to the drive waveform generation unit 13 and the voltage gain setting unit 14.

The initial position deviation adjustment unit 17 controls the motor 11 so that the position deviation before control of the motor 11 starts (hereinafter referred to as the initial position deviation) falls within a predetermined range (tolerable range). After processing by the initial position deviation adjustment unit 17 is performed, the control unit 16 starts position feedback control of the motor 11.

The drive waveform generating unit 13 may have a synchronization unit that synchronizes the phase (mechanical angle) of the actual rotational position detected by the rotational position detecting unit 12 with the phase (electrical angle) of the drive waveform generated by the drive waveform generating unit 13, and a phase difference setting unit that maintains a predetermined phase difference between the actual rotational position and the drive waveform when the phases are synchronized by the synchronization unit. The phase difference corresponds to an advance angle, and the maximum torque can be generated in the motor 11 by leading the phase of the drive waveform by 90 degrees relative to the rotational position when the motor 11 starts to drive.

Figure 2 shows a specific configuration of a motor control device when a stepping motor 101 is used as the motor 11 shown in Figure 1. The rotational position detection unit 12 shown in Figure 1 is composed of the ENC magnet 103, Hall element unit 104, amplifier 107, AD conversion circuit 108, and position ENC circuit 109 shown in Figure 2. The drive waveform generation unit 13 shown in Figure 1 corresponds to the drive waveform generation circuit 110 shown in Figure 2, and the voltage gain setting unit 14 shown in Figure 1 corresponds to the PWM generator 112. The target rotational position holding unit 15 and control unit 16 shown in Figure 1 correspond to the CPU 111. The motor driver 113 is a drive circuit that receives a signal from the PWM generator 112 of the motor control device and applies a drive voltage to the stepping motor 101.

The stepping motor 101 has a rotor magnet 120, a rotor shaft 102 that rotates integrally with the rotor magnet 120, four stators (A+, A-, B+, B-) 116, 117, 118, 119, an A-phase coil 114, a B-phase coil 115, and a reset mechanism 121. The rotor shaft 102 is equipped with an ENC magnet 103 and a reset mechanism 121. The ENC magnet 103 is magnetized so as to generate a sinusoidal magnetic field according to the rotational position. The reset mechanism 121 outputs a signal that changes at one specific rotational position of the rotor shaft 102. The output signal provides a reference for the absolute value of the rotational position of the rotor shaft 102. The reset mechanism 121 includes, for example, a moving body that moves translationally in response to the rotation of a screw portion provided on the rotor shaft 102, and a photointerrupter (PI), and is configured to change the output signal of the PI when a slit provided in the moving body passes through the PI.

The Hall element unit 104 has two Hall elements 105 and 106. The Hall elements 105 and 106 each detect a change in the magnetic field caused by the rotation of the ENC magnet 103 at their respective positions and output a detection signal. The ENC magnet 103 and the Hall element unit 104 form a magnetic encoder. Note that an optical encoder may be used instead of the magnetic encoder. In this case, the ENC magnet 103 is replaced with a scale having a pattern in which reflective and non-reflective portions or translucent and non-translucent portions are alternately arranged, and the Hall element unit 104 is replaced with an LED and a photodiode.

Figure 3(a) shows the external appearance of the stepping motor 101. A disk-shaped ENC magnet 103 is fixed to the rotor shaft 102 of the stepping motor 101, and a Hall element unit 104 is held by a support member (not shown) at a position where a change in the magnetic field caused by the rotation of the ENC magnet 103 can be detected. A wiring 201 extends from the stepping motor 101 to the outside, and this wiring 201 is connected to the motor driver 113.

Figure 3 (b) shows the positional relationship between the ENC magnet 103 and the Hall element unit 104 (Hall elements 105, 106). The ENC magnet 103 has five N poles and five S poles magnetized alternately in the circumferential direction (rotation direction) at physical angles of 36° each. The Hall elements 105 and 106 are arranged at equal distances from the center position of the ENC magnet 103. The physical angle formed by the line passing through the center of each Hall element and the center position of the ENC magnet 103 with respect to the line passing through the midpoint between the Hall elements 105 and 106 and the center position of the ENC magnet 103 is 18°. With this arrangement, the detection signals from the Hall elements 105 and 106 have a phase difference of 90° from each other (i.e., a Sin and Cos relationship).

The amplifier 107 shown in FIG. 2 amplifies the two detection signals from the Hall elements 105 and 106 and transmits the amplified detection signals to the AD conversion circuit 108. The AD conversion circuit 108 converts the two input detection signals (voltage signals) into numerical values and outputs the result to the position ENC circuit 109 as a digital numerical signal (hereinafter referred to as a sensor signal).

The position ENC circuit 109 performs offset adjustment and gain adjustment on the two input sensor signals, and generates a TAN value from the two adjusted sensor signals (sine wave signals). Furthermore, the position ENC circuit 109 performs an inverse TAN operation on the TAN value to generate rotation angle information, and integrates this rotation angle information to generate rotation position information. The generated rotation position information is output to the drive waveform generation circuit 110.

The drive waveform generating circuit 110 can switch between OPEN drive, which outputs a drive waveform as two sine wave signals with different phases at a set frequency, and CLOSE drive, which outputs two drive waveforms linked to rotational position information from the position ENC circuit 109. These switching modes are performed according to commands from the CPU 111. The CPU 111 sets the frequency and amplitude gain of the sine wave signal output during OPEN drive, and also initializes the position count value in the position ENC circuit 109, which will be described later.

Figure 4 (a) shows the specific configuration of the position ENC circuit 109 and the drive waveform generation circuit 110. The Apos generation unit 301 and the Bpos generation unit 302 make up the position ENC circuit 109, and the drive waveform phase determination unit 303 to the drive phase difference change time setting unit 307 make up the drive waveform generation circuit 110.

The two sensor signals from the Hall elements 105, 106 and the AD conversion circuit 108 are input to the Apos generation unit 301 of the position ENC circuit 109. The Apos generation unit 301 performs offset adjustment and gain adjustment on the two sensor signals, and calculates the rotational position using the adjusted sensor signals. More specifically, the Apos generation unit 301 first performs offset adjustment and gain adjustment on the two input sensor signals (sine wave signals) as preprocessing to make these offsets and gains the same. The offset adjustment and gain adjustment are performed using the peak value and bottom value of the two sine wave signals obtained by rotating the stepping motor 101 in OPEN drive.

Next, the Apos generation unit 301 generates a TAN value from two sensor signals that have a phase difference of 90° after offset adjustment and gain adjustment, and integrates the rotation angle information obtained by performing an inverse TAN operation on the generated value to generate the rotation position information Apos.

Figures 5(a) to (c) show the relationship between the two sensor signals and the rotational position information Apos after offset and gain adjustment. Figures 5(a) and (b) each show two sensor signals with a phase difference of 90°, with the horizontal axis showing the amount of rotation. In this embodiment, when the two sensor signals output one wavelength of a sine wave, the rotational position can be detected with a position resolution of 0 to 1023 (1024 counts). Since the ENC magnet 103 has a total of 10 poles, including north and south poles, sensor signals for five wavelengths are output with one rotation of the stepping motor 101. Figure 5(c) shows the rotational position information (detected position count value) Apos obtained from the two sensor signals.

The Bpos generation unit 302 generates rotational position information Bpos having an arbitrary offset value for the rotational position information Apos. The rotational position information Bpos can be rewritten by the CPU 111 to an arbitrary value at an arbitrary timing, and the Bpos generation unit 302 records the difference between the rewritten Bpos and Apos as an offset value at the rewrite timing.

The Bpos generation unit 302 further generates rotational position information Bpos by applying the recorded offset value shown in FIG. 4(c) to the rotational position information Apos shown in FIG. 4(b) over the total amount of rotation (horizontal axis). The offset value is associated with an absolute position value that is arbitrarily determined at the operation timing of the reset mechanism 121. The Bpos generation unit 302 calculates rotational position information Bpos that has an offset for each rotation of the stepping motor 101, i.e., is made into an absolute position. The calculated rotational position information Bpos is output to the drive waveform phase determination unit 303.

The drive waveform phase determination unit 303 determines the phase count information of the drive waveform that is ultimately applied to the A-phase coil 114 and the B-phase coil 115, and outputs a PWM value corresponding to the phase count to the PWM generator 112. The drive waveform phase determination unit 303 can switch between OPEN drive, which outputs phase count information based on a command from the OPEN drive count unit 304, and position-linked drive, which outputs phase count information based on the rotational position information Bpos.

Switching between OPEN drive and position-linked drive is performed by CPU 111 setting the switch in drive waveform phase determination unit 303. When switching to OPEN drive, CPU 111 commands the frequency of the drive waveform to OPEN drive count unit 304, and further sets the amplitude gain of the drive waveform in drive waveform phase determination unit 303, so that drive waveform phase determination unit 303 outputs a drive waveform with an amplitude corresponding to the amplitude gain set at the commanded frequency.

On the other hand, when switching to position-linked drive, the CPU 111 calculates a value by offsetting the lowest 10 bits of the rotational position information Bpos with the STC_OFS value set through the steady-state phase difference setting unit 305 and the PHS_OFS value set through the drive phase difference setting unit 306. This calculated value becomes the phase count value of the drive waveform, and the output value of the phase equivalent to this phase count value is selected as the drive waveform. This relationship is shown in the graphs of Figures 4(d) and (e). Figure 4(d) shows the lowest 10 bits of the rotational position information Bpos versus the amount of rotation, and Figure 4(e) shows the phase of the drive waveform versus the amount of rotation.

As can be seen from Figures 4(d) and (e), the phase of the drive waveform is determined by adding both STC_OFS and PHS_OFS to the lowest 10 bits of Bpos to give it an offset value, and it appears that only one of STC_OFS or PHS_OFS is required.

However, STC_OFS has the role of managing the stable positions of the detected position count value and the phase count value of the drive waveform, and PHS_OFS has the role of managing the phase difference for torque generation. STC_OFS is a value that prevents the phase of the rotor magnet 120 and the phase of the drive waveform from shifting the moment the position interlocking function is turned ON/OFF, and is associated with the offset of Bpos. Furthermore, PHS_OFS is a value used to determine how much advance angle to set for the drive waveform. By setting the value of PHS_OFS, it is possible to adjust the direction of rotation of the rotor magnet 120 (rotor shaft 102) and the magnitude of the torque.

The drive waveform generating circuit 110 also has a function that, when the setting value in the drive phase difference setting unit 306 is changed, gradually changes the phase difference over a certain period of time, rather than instantly switching from the phase difference before setting to the phase difference after setting. This function can be turned ON/OFF by the CPU 111, which sets the phase difference change time PS_TIME for this function in the drive phase difference change time setting unit 307 on the order of μs to ms.

The PWM generator 112 shown in FIG. 2 outputs a PWM signal corresponding to the PWM command value output from the drive waveform generating circuit 110 to the motor driver 113. The relationship between the count value of the electrical angle of A phase and B phase and the PWM command value is shown in FIG. 6(a) and (b). In FIG. 6(a) and (b), the horizontal axis indicates the table number, and has a resolution of 1024, similar to the drive waveform in FIG. 4(e). The vertical axis indicates the duty % value as the PWM command value. The A phase drive voltage waveform is the drive waveform applied to the A phase coil 114 (hereinafter referred to as the A phase waveform), and the B phase drive voltage waveform is the drive waveform applied to the B phase coil 115 (hereinafter referred to as the B phase waveform).

Figure 6(a) shows a case where the table number is counted up, the B-phase waveform leads the A-phase waveform by 90°, and the stepping motor 101 rotates in a clockwise (CW) direction. Figure 6(b) shows a case where the table number is counted up, the A-phase waveform leads the B-phase waveform by 90°, and the stepping motor 101 rotates in a counterclockwise (CCW) direction. The Duty% value on the vertical axis increases or decreases according to the Gain setting value from the CPU 111, but in this embodiment it is assumed that an appropriate value is set for the rotation of the stepping motor 101.

The motor driver 113 amplifies the PWM command value output from the PWM generator 112 and applies a drive voltage to the A-phase coil 114 and the B-phase coil 115. The applied drive voltage is a high-frequency signal corresponding to the PWM signal, but since the current value signal generated in each coil is equivalent to being low-pass filtered by the inductance (L) component of the coil, the coils are treated as effectively receiving the sine wave drive voltage shown in Figures 6(a) and (b).

The Stator A+ 116 and Stator A- 117 shown in FIG. 2 each function to concentrate and emit the magnetic field generated at both ends of the A-phase coil 114. The Stator B+ 118 and Stator B- 119 each function to concentrate and emit the magnetic field generated at both ends of the B-phase coil 115. FIG. 3(c) shows the positional relationship between the stator group (Stator A+ 116, Stator A- 117, Stator B+ 118, and Stator B- 119) and the rotor magnet 120.

As shown in FIG. 3(c), Stator A+ 116, Stator B+ 118, Stator A- 117 and Stator B- 119 are arranged in this order in the CCW direction, with five of each at a physical angle of 18°. Rotor magnet 120 is arranged in the center of the stator group, and has a total of 10 poles, with five N poles and five S poles alternating in the direction of rotation. Rotor magnet 120 rotates a physical angle of 72° every time one wavelength of the sine wave of the drive waveform is output, and rotates a physical angle of 360° when five wavelengths of the sine wave of the drive waveform are output.

In this embodiment, the ENC magnet 103 and the rotor magnet 120 each have 10 poles, but the number of poles for each can be selected as appropriate.

Figure 12 shows the configuration of a focal plane shutter unit 300 as an optical unit using a stepping motor 101 (100a, 100b) as a drive source. This focal plane shutter unit 300 is mounted on a digital camera 500 as an imaging device (optical device) shown in Figure 13, and controls the amount of exposure of an imaging element 400 such as a CMOS sensor to light from an imaging optical system 601 in an interchangeable lens 600.

The focal plane shutter unit 300 has a shutter base 310 having an opening (aperture) 310a through which light passes, a front curtain unit and a rear curtain unit that open and close the aperture 310a, front curtain and rear curtain stepping motors 101a, 101b, and a front curtain drive system and a rear curtain drive system that transmit the rotation of these stepping motors 101a, 101b to the front curtain unit and rear curtain unit, respectively. Wiring 201 is connected to the stepping motors 101a, 101b to apply a drive voltage thereto.

The front curtain unit has a plurality of front curtain shutter blades 311, two front curtain arms 312 rotatably connected to the front curtain shutter blades 311, and a front curtain drive lever 313 that rotates one of the front curtain arms 312. The rear curtain unit has a plurality of rear curtain shutter blades 321, two rear curtain arms 322 rotatably connected to the rear curtain shutter blades 321, and a rear curtain drive lever 323 that rotates one of the rear curtain arms 322.

Figure 7 shows an enlarged view of the front curtain drive system. The front curtain drive system has a first drive gear 301 fixed to the rotor shaft 102 of the front curtain stepping motor 101a, an idler gear 302 meshing with the first drive gear 301, and a second drive gear 303 meshing with the idler gear 302. The second drive gear 303 is connected to a front curtain drive lever 313. The configuration of the rear curtain drive system is the same as that of the front curtain drive system.

When the leading curtain stepping motor 101a is rotated, its rotation is transmitted to the leading curtain drive lever 313 via the first drive gear 301, the idler gear 302, and the second drive gear 303, and the leading curtain drive lever 313 rotates to rotate the leading curtain arm 312, causing the leading curtain shutter blade 311 to travel. Similarly, when the trailing curtain stepping motor 101b is rotated, its rotation is transmitted to the trailing curtain drive lever 323 via the first drive gear 301, the idler gear 302, and the second drive gear 303, and the trailing curtain drive lever 323 rotates to rotate the trailing curtain arm 322, causing the trailing curtain shutter blade 321 to travel.

When the image sensor is exposed, the front curtain stepping motor 101a rotates to move the front curtain shutter blade 311 from an initial position in an unfolded state (closed state) to a running end position in an overlapped state (open state), and after a predetermined shutter time has elapsed, the rear curtain stepping motor 101b rotates to move the rear curtain shutter blade 321 from the initial position in an overlapped state to a running end position in an unfolded state. After exposure is completed, the front curtain and rear curtain stepping motors 101a and 101b rotate to move the front curtain and rear curtain shutter blades 311 and 321 from the running end position back to their initial positions. In this way, the front curtain and rear curtain units are driven in both the open and closed directions by the front curtain and rear curtain stepping motors 101a and 101b.

In this embodiment, the rotation of the rotor shaft 102 acts directly on the front and rear curtain units, so the amount of rotation of the stepping motors 101a and 101b during and after exposure is less than a physical angle of 360° (i.e., one rotation).

The rotational positions of the stepping motors 101a and 101b can be obtained by detecting the change in the magnetic field generated by the ENC magnet 103 using the Hall elements 105 and 106, as described above. The ENC magnets can be arranged to rotate together with the gears of the front and rear curtain drive systems, and the rotational position information obtained by detecting the change in the magnetic field caused by the rotation of the gears using the Hall elements can be converted into the rotational position of the stepping motor using a gear ratio. This is also true when an optical encoder is used instead of a magnetic encoder.

When the image sensor is exposed as described above, the stepping motor 101a for the front curtain is rotated in the CW direction from the initial target rotation position N0 as shown in FIG. 7 to move the front curtain unit from the initial position in which it is in an unfolded state to the open position in which it is in an overlapped state. After the exposure is completed, the stepping motor 101a is rotated in the CCW direction to the initial target rotation position N0 to return the front curtain unit from the open position to the initial position. The same applies to the stepping motor 101b for the rear curtain.

The initial target rotation position N0 can be set to any rotation position. A stopper portion may be provided on the first drive gear 301, and the initial target rotation position N0 may be set to a rotation position at which the stepping motor 101a is forcibly stopped when the stopper portion abuts against an abutment portion provided on the shutter base 310 during return rotation of the stepping motor 101a in the CCW direction. In addition, when a strong collision between the stopper portion and the abutment portion is to be avoided, the initial target rotation position N0 may be set to a rotation position slightly in the CW direction from the rotation position at which the stopper portion abuts against the abutment portion.

The configuration of the front and rear curtain drive system may be other than that shown in FIG. 7, so long as the rotation of the rotor shaft 102 acts directly on the front and rear curtain units. For example, a drive lever may be used instead of a drive gear.

In a focal plane shutter unit configured as described above, even a slight deviation in the trajectory of the shutter blades, particularly in the exposure section, from the target trajectory will result in uneven exposure of the image sensor. For this reason, even if there are factors that cause the trajectory of the shutter blades to vary, such as temperature changes or mechanical changes over time, it is necessary to control the stepping motor 101 so that the trajectory of the shutter blades approaches or matches a predetermined target trajectory.

In this embodiment, the stepping motor 101 is subjected to position feedback control to absorb fluctuations in the running trajectory and bring the actual running trajectory closer to or into agreement with the target running trajectory. The initial target rotation position N0 described above is used to calculate the initial position deviation in this position feedback control.

Figure 8 shows the trajectories of multiple target rotation positions (vertical axis) of the stepping motor 101 against the control time (horizontal axis) in position feedback control, that is, the target running trajectory of the shutter blades. When the stepping motor 101 is rotated in the CW direction from the initial target rotation position N0, which is the first (initial) target rotation position of the position feedback control, to run the shutter blades, the time until the exposure start position shown as the curtain origin Nm in the figure is reached is the time lag, and the running time from the curtain origin Nm to the exposure end position shown as the curtain end Nn is the curtain speed. The time lag and curtain speed are determined as specifications for each product of the focal plane shutter unit, and the stepping motor 101 must be controlled to satisfy the specifications. And since deviation of the actual running trajectory (actual running trajectory) from the target running trajectory in the exposure section from the curtain origin Nm to the curtain end Nn leads to uneven exposure, high control accuracy is required.

In this embodiment, the target rotational position information is the trajectory (set) of the target rotational positions of the stepping motor 101 in the running section from the initial target rotational position N0 to the end of the run Nn, and the stepping motor 101 is controlled by position feedback control so that the trajectory of the actual rotational position of the stepping motor 101 approaches or coincides with the trajectory of the target rotational position.

The target rotational position information is information for each control cycle of the CPU 111, and representative data that satisfies the specifications for time lag and curtain speed under certain driving conditions may be used as the target rotational position information. In addition, the target rotational position information does not have to be based on data obtained by actually driving the stepping motor 101, and may be data that is arbitrarily created within the range in which the stepping motor 101 can be driven.

For example, if the control period of the CPU 111 is 16 kHz (62 μs) and the time required to travel from the initial target rotational position N0 to the end of the rotation Nn is 10 ms, then approximately 162 pieces of data (dots in the figure: some omitted) every 62 μs will be prepared as the target rotational positions included in the target rotational position information. Note that data for target rotational positions after the end of the rotation Nn may also be retained. The control period and the number of pieces of data for the target rotational positions included in the target rotational position information can also be selected as appropriate.

The torque characteristics of the stepping motor 101 change depending on the temperature, and generally the torque characteristics improve in a low-temperature environment and decrease in a high-temperature environment. If position feedback control is not performed for a certain target rotational position information, the actual rotational position of the stepping motor 101 is likely to exceed the target rotational position in a low-temperature environment and to fall below the target rotational position in a high-temperature environment. If position feedback control is performed for such a stepping motor 101, the trajectory of the actual rotational position may deviate from the trajectory of the target rotational position from the initial target rotational position N0 to a certain target rotational position. However, if the actual rotational position approaches or matches the target rotational position by the time the curtain origin Nm is reached, and if the trajectory of the actual rotational position approaches or matches the trajectory of the target rotational position from the curtain origin Nm to the curtain end Nn, uneven exposure can be suppressed.

Figures 9(a) and (b) show the relationship between the initial position deviation and the position feedback controllability in this embodiment. Figure 9(a) shows the physical angle error value when position feedback control is performed from the initial target rotation position N0 to the end of the rotation Nn, and Figure 9(b) shows the voltage gain value in the same case.

The initial target rotation position N0 is a rotation position slightly in the CW direction from the rotation position where the stopper and the contact portion contact each other, and the position feedback control is started from a rotation position shifted from the initial target rotation position N0 in the CCW direction by the initial position deviations a, b, c, and d. The initial position deviations are a>b>c>d in order, and d is almost 0. Proportional-Integral-Differential (PID) control is used for the position feedback control, and the position deviation, i.e., the physical angle error value, is used as an input to determine the output control amount and control the voltage gain value, that is, the drive voltage applied to the stepping motor 101. Specifically, the voltage gain value is adjusted from 0 to 511 (512 counts) to control the drive voltage applied to the stepping motor 101. The drive conditions of the stepping motor 101 other than the initial position deviations a, b, c, and d are the same, and the same lead angle value and the same PID parameters are used. Instead of PID control, various control methods such as PI control and PD control may be used.

In Figures 9(a) and (b), the larger the initial position deviation, the more the physical angle error value fluctuates, and the voltage gain value fluctuates to compensate for this. At initial position deviation a, there is oscillation and controllability is extremely poor. At initial position deviation b, there is also a tendency for oscillation. At initial position deviation c, the physical angle error value converges to a certain extent, and at initial position deviation d, controllability is the best.

If the physical angle error value is large from the beginning Nm to the end Nn of the curtain, unnoticeable uneven exposure will occur. For this reason, the allowable value of the initial position deviation is determined according to the allowable uneven exposure. Therefore, in the position feedback control of the stepping motor 101 used as the driving source of the focal plane shutter unit, it is important to make the initial position deviation as small as possible.

The flowchart in FIG. 10 shows the control process (control method) of the stepping motor 101, specifically the process executed by the control unit 16 and initial position deviation adjustment unit 17 shown in FIG. 1. The control unit 16 and initial position deviation adjustment unit 17, which are configured by a computer, execute this process according to a computer program. Note that before step S1000, the stepping motor 101 is driven in the CCW direction with the initial target rotation position N0 as the target stop position so as to return the shutter blades, which have traveled to the travel end position in the previous exposure, to their initial positions. However, depending on the stopping accuracy of the stepping motor 101, variations in the actual stop position may occur, and the initial position deviation may fluctuate.

When exposure, i.e., driving the stepping motor 101 in the CW direction, is instructed in step S1000, the initial position deviation adjustment unit 17 starts the initial position deviation adjustment process in step S1001.

First, the initial position deviation adjustment unit 17 calculates the initial position deviation in step S1002. The initial position deviation is calculated as the difference between the initial target rotational position N0 and the current actual rotational position. The initial target rotational position N0 means the initial target rotational position in the target rotational position information used in the control of the stepping motor 101 during the previous exposure. In addition, the current actual rotational position is obtained via the CPU 111 from the rotational position information generated by the position ENC circuit 109 using the detection signals from the Hall elements 105 and 106 shown in FIG. 2.

In the next step S1003, the initial position deviation adjustment unit 17 determines whether the obtained initial position deviation is within the allowable range. The allowable range of the initial position deviation is determined according to the allowable range of exposure unevenness. If the initial position deviation is within the allowable range, the initial position deviation adjustment unit 17 uses the target rotational position information held by the target rotational position holding unit 15 for position feedback control as is. In this case, the initial position deviation adjustment process ends, and in step S1013, the control unit 16 drives the stepping motor 101 in the CW direction by position feedback control using the target rotational position information.

On the other hand, if the initial position deviation is outside the allowable range, the position feedback controllability is reduced, and adjustment is required to absorb this initial position deviation. For this reason, the initial position deviation adjustment unit 17 proceeds to step S1004 and selects a mode. Below, a case where mode 1 (first processing) is selected is described. A case where mode 2 (second processing) is selected is described in the next Example 2.

In mode 1, in step S1005, the initial position deviation adjustment unit 17 determines whether the initial position deviation is greater than 0. If the initial position deviation is greater than 0, the current actual rotation position is located on the CCW side of the initial target rotation position N0, and if it is less than 0, the current rotation position is located on the CW side of the initial target rotation position N0. If the current actual rotation position is located on the CCW side of the initial target rotation position N0, the initial position deviation adjustment unit 17 proceeds to step S1006. If the current actual rotation position is located on the CW side of the initial target rotation position N0, the initial position deviation adjustment unit 17 proceeds to step S1007.

In step S1006, the initial position deviation adjustment unit 17 drives the stepping motor 101 in the CW direction. In this case, the stepping motor 101 may be driven in either OPEN or CLOSE mode, but OPEN mode is more preferable from the viewpoint of stopping position accuracy.

Next, in step S1008, the initial position deviation adjustment unit 17 monitors the actual rotational position and initial position deviation of the stepping motor 101, and when the initial position deviation falls within the allowable range, stops driving the stepping motor 101 in the CW direction.

Next, in step S1010, the initial position deviation adjustment unit 17 acquires target rotational position information corresponding to the initial position deviation adjustment in the CW direction from two pieces of target rotational position information previously stored according to the rotational directions (CW direction and CCW direction) for adjusting the initial position deviation of the stepping motor 101, and changes (updates) the target rotational position information stored in the target rotational position storage unit 15 to the acquired target rotational position information.

On the other hand, in step S1007, the initial position deviation adjustment unit 17 drives the stepping motor 101 in the CCW direction. In this case, the stepping motor 101 may be driven in either OPEN or CLOSE mode, but OPEN mode is more preferable from the viewpoint of stopping position accuracy.

Next, in step S1009, the initial position deviation adjustment unit 17 monitors the actual rotational position and initial position deviation of the stepping motor 101, and when the initial position deviation falls within the allowable range, stops driving the stepping motor 101 in the CCW direction.

Next, in step S1011, the initial position deviation adjustment unit 17 acquires target rotational position information in which the initial position deviation adjustment corresponds to the CCW direction from the above two pieces of target rotational position information, and changes (updates) the target rotational position information held by the target rotational position holding unit 15 to the acquired target rotational position information.

The reason for making the target rotational position information different for the CW direction and the CCW direction is that the direction in which the gap (play) due to backlash appears between the first drive gear 301, the idler gear 302, and the second drive gear 303 differs depending on the rotation direction of the stepping motor 101. In order to make the direction in which the gap appears the same, it is necessary to rotate the stepping motor 101. For this reason, the target rotational position information is made different depending on the rotation direction. In the target rotational position information for each rotation direction, at least a portion of the target rotational position from the initial target rotational position to just before the curtain origin Nm differs, and the target rotational position from the curtain origin Nm to the curtain end Nn is the same regardless of the rotation direction of the initial position deviation adjustment.

In addition, if driving the stepping motor 101 in the CW direction in step S1013 is performed from a state where backlash in the CW direction has been eliminated, then in step S1007, the stepping motor 101 is first driven in the CCW direction from the initial target rotation position N0, and then steps S1006, S1008, and S1010 are performed, although this is not shown in FIG. 10. However, if the effect of backlash is small, such as when the gear play has been eliminated, the same target rotation position information may be used regardless of the rotation direction of the stepping motor 101.

When the initial position deviation adjustment process is completed in step S1010 or step S1011, in step S1013, the control unit 16 drives the stepping motor 101 in the CW direction by position feedback control using the changed target rotational position information.

As described above, in this embodiment, position feedback control of the stepping motor 101 is started after the actual rotational position of the stepping motor 101 is brought close to or coincides with the initial target rotational position, i.e., after the initial position deviation is within an allowable range. This makes it possible to absorb the initial position deviation and obtain good controllability when performing position feedback control on the stepping motor 101, which requires high speed tracking within a small number of rotations (short control time).

Next, a second embodiment of the present invention will be described. In this embodiment, an initial position deviation adjustment process different from that in the first embodiment will be described, which is executed by the initial position deviation adjustment unit 17 described in the first embodiment. The configuration of the motor control device that controls the stepping motor 101 and the method of position feedback control are the same as those in the first embodiment. In this embodiment, a case where mode 2 is selected in step S1004 in the flowchart of FIG. 10 will be described.

In mode 2, in step S1012, the initial position deviation adjustment unit 17 does not rotate the stepping motor 101 to bring the initial position deviation within an acceptable range as in mode 1, but changes the initial target rotation position N0 to approach or match the actual rotation position, and further changes the target rotation position information held by the target rotation position holding unit 15 in accordance with the change in the initial target rotation position N0.

The change in the target rotational position information in step S1012 will be described with reference to Figures 11(a) and (b). Figure 11(a) shows the relationship between the target rotational position information before the update and the actual rotational position in step S1000. The actual rotational position is located on the CW side of the initial target rotational position N0.

In order to absorb this initial position deviation, the initial position deviation adjustment unit 17 changes the initial target rotation position N0 to approach or match the actual rotation position, as shown in FIG. 11(b). Furthermore, the initial position deviation adjustment unit 17 newly calculates the second to Xth target rotation positions N1 to Nx so that the trajectory from the changed initial target rotation position N0 to an arbitrary Xth target rotation position Nx that is the second or later and before the curtain origin Nm smoothly connects to the trajectory from the (X+1)th target rotation position Nx+1, and changes the target rotation position information held by the target rotation position holding unit 15 using these newly calculated target rotation positions N1 to Nx. At this time, the target rotation positions from Nx+1 to the curtain origin Nm, and further from the curtain origin Nm to the curtain end Nn, are not changed.

A similar initial position deviation adjustment process is performed when the actual rotation position is on the CCW side of the initial target rotation position N0 before the change. In this case, the trajectory indicated by the changed target rotation position information will be a trajectory that starts on the CCW side of the trajectory indicated by the target rotation position information before the change.

Once the initial position deviation adjustment process is completed in this manner, the control unit 16 drives the stepping motor 101 in the CW direction by position feedback control using the changed target rotational position information in step S1013.

It is also possible to provide an additional step for determining the mode selected in step S1004, and use mode 1 or mode 2 depending on the result of the determination. Mode 1 requires more processing time than mode 2 to rotate the stepping motor 101. Also, in mode 2, if the actual rotation position is significantly deviated from the initial target rotation position N0 to the CW side, the travel (acceleration) section to the curtain base Nm becomes shorter, which may result in the curtain speed becoming slower and not satisfying the specifications. For this reason, it is possible to select mode 1 even if it requires processing time when the initial position deviation is too large to the CW side, exceeding a first predetermined value, and to select mode 2 when the initial position deviation is smaller than a second predetermined value.

In addition, when selecting the mode in step S1004, it is possible to select both mode 1 and mode 2. In steps S1008 and S1009 of mode 1, the actual rotational position of the stepping motor 101 is monitored, and when the initial position deviation falls within the allowable range, the rotation of the stepping motor 101 is stopped. At this time, the rotational position after stopping may be slightly shifted due to uneven magnetization of the rotor magnet 120 or mechanical interference with the rotation of the rotor magnet 120. In such a case, it is possible to reduce the initial position deviation including the deviation by using mode 2. In this case, the process proceeds to step S1012 after step S1008 or step S1009, or to step S1012 after step S1010 or step S1011.

As described above, in this embodiment, position feedback control of the stepping motor 101 is started after some target rotation positions, including the initial target rotation position, among the target rotation position information are brought close to or coincident with the actual rotation position of the stepping motor 101, i.e., after the initial position deviation is within an acceptable range. This makes it possible to absorb the initial position deviation and obtain good controllability when performing position feedback control on the stepping motor 101, which requires high speed tracking within a small number of rotations (short control time).

Note that focal plane shutter units include not only those in which both the front and rear curtains open and close their shutter blades as described in the first and second embodiments, but also those in which only the rear curtain opens and closes its shutter blades while the front curtain uses an electronic shutter for the image sensor. The stepping motor used in the latter focal plane shutter unit may also be subjected to the process of absorbing the initial position deviation described in the first and second embodiments.

In addition, in the first and second embodiments, the target rotational position information for the front and rear curtains from the beginning Nm to the end Nn is the same, but in response to a change in the exposure control of the front curtain, the target rotational position information for the rear curtain from the beginning Nm to the end Nn may be changed to match the exposure control of the front curtain. For example, in the second embodiment, the target rotational position information for the front curtain may be created up to the end Nn, in which case the target rotational position information for the exposure section is changed before and after. As the shutter unit only needs to align the trajectories of the blades in the exposure sections of the front and rear curtains, the target rotational position information for the exposure section of the rear curtain may be made to match the target rotational position information for the exposure section of the front curtain after the change.

Furthermore, if the controllability of the front curtain changes due to aging or deterioration, it may be difficult to continue using the data for the exposure section of the target rotational position information, and the information may need to be changed by internal processing of the computer. In this case as well, the target rotational position information for the exposure section of the rear curtain should be made to match the target rotational position information for the exposure section of the front curtain after the change. The same is true in reverse.

Furthermore, in the first and second embodiments, the motor that drives the shutter unit mounted on the imaging device is described as the controlled object, but the motor of other optical units, such as a mirror unit mounted on the imaging device and driving a quick return mirror, or an aperture unit mounted on the imaging device or an interchangeable lens (optical device) and driving aperture blades, may also be controlled. Although the mirror unit does not require the same control accuracy of the motor's rotational position during the exposure interval as the shutter unit, it is possible to increase the controllability of the mirror drive motor and improve stopping accuracy by absorbing the initial position deviation. By improving the stopping accuracy, it is possible to reduce the transition time to the next operation and improve the controllability of the next operation. A similar effect can be obtained with the aperture unit.

Next, a third embodiment of the present invention will be described. The motor control device of this embodiment has the initial position deviation adjustment unit 17 described in the first and second embodiments. The configuration of the motor control device that controls the stepping motor 101 in this embodiment and the method of position feedback control are the same as those in the first and second embodiments.

In this embodiment, a robot manipulator device will be described as the control target. FIG. 14 shows an example of the configuration of a robot manipulator device 700. The robot manipulator device constitutes a gripping and transporting system that grips a stationary gripping target and moves the gripping target to a specified position.

In the robot manipulator device 700, a manipulator is formed by a base 701, an arm 702, and hands 703a and 703b. The arm 702 is connected to the base 701 so as to be able to rotate and swing. The arm 702 is formed by a first arm 702a, a second arm 702b, and a third arm 702c which are connected to each other so as to be able to swing. Hands 703a and 703b are connected to the tip of the third arm 702c so as to be able to open and close. The above-mentioned rotation, swing, and rotation are driven by motors 704a to 704e arranged at each connection between the base 701 and the arm 703. The hands 703a and 703b are driven to open and close by motors 704g and 704f. The rotation and swinging of the base 701 and arm 702 moves the hands 703a and 703b to any spatial coordinates, and the object to be grasped is grasped and transported by opening and closing the hands 703a and 703b.

In this embodiment, a robot manipulator device equipped with hands 703a and 703b having a gripping function is described, but an attachment having a different function may be attached to the arm 702 instead of the hand. For example, a welding torch may be attached to make it a welding robot manipulator device, or an attachment having a material processing/cutting function may be attached to make it a processing/cutting robot manipulator device. Also, an attachment having a fixed amount of liquid or the like may be attached to make it a dispenser robot manipulator device.

Motors 704a to 704g may be stepping motors 101 as in the first and second embodiments, or may be DC brushless motors that are often used in industrial robot applications.

Since motors generally rotate at high speeds and have low output torque, robots often use a reduction mechanism to reduce the motor's rotation speed and increase the torque. Manipulators that are operated with low output torque often use a small reduction ratio. When the reduction ratio is small, the relationship between the amount of rotation of the motor and the amount of rotation of the arm or hand becomes closer, so it is necessary to consider the issues involved in driving the motor at high speeds and low rotation speeds.

The reduction mechanism uses a gear such as the idler gear 302 described in Example 1, and the drive gear provided on the output shaft of each motor is engaged with the gear of the reduction mechanism, so the effect of backlash must be taken into consideration. In addition, since backlash occurs at each connection, even if the effect at each connection is minute, it can cause an unacceptable error overall.

To achieve stable repetitive motion in a robot manipulator device, position feedback control is used to control the robot to follow an ideal trajectory between the start point of the motion and the target end point. The ideal trajectory may be position trajectory information stored in advance as internal information for control. In addition, position trajectory information calculated each time from information on the motor's rotation speed (acceleration operation time, deceleration operation time) that is preset according to distance information between any start point and end point may be used. In addition, distance information between the start point and end point can also be obtained from image information from an external camera (not shown). Furthermore, in robot manipulator devices for processing/cutting or dispensing, ideal trajectories may be set that are curved or circular in addition to straight lines, and it is required to follow ideal trajectories of various shapes.

Even when hands 703a and 703b cooperate with each other to perform a gripping operation, it is preferable for each to follow an ideal trajectory. If one hand touches the object to be gripped first, the object to be gripped may shift in position or vibrate, which may reduce the stability of the gripping operation. For this reason, a stable gripping operation is possible when hands 703a and 703b each follow an ideal trajectory.

In position feedback control at high speeds and low rotation speeds of a motor, it is necessary to take into account the magnitude of the initial position deviation at the start of drive. The initial position deviation becomes large if the stopping accuracy of the previous drive was low, and also changes depending on the gear meshing state (the magnitude of play due to backlash and the direction of bias). As described in Example 1, if the initial position deviation is large, the controllability of the position feedback decreases, so it is desirable to make the initial position deviation as small as possible. In addition, depending on the direction of the gear play in the reduction mechanism, the amount of deviation from the target at the tip of the arm, known as lost motion, increases. To reduce lost motion, it is preferable for the play to be biased to one side at the start of drive.

General-purpose, small, lightweight robot manipulator devices are used in a variety of locations and environments, and the vibration state of the robot manipulator device changes depending on the location and environment, and the torque characteristics of the motor change depending on the temperature. In addition, the position accuracy may decrease due to thermal expansion and contraction of the robot body. Such fluctuations in characteristics cause fluctuations in the position controllability of the motor, leading to unstable stopping accuracy and variations in the magnitude of the initial position deviation.

By applying the motor control device described in Examples 1 and 2 to a robot manipulator device in which the magnitude of such initial position deviation fluctuates, it is possible to reduce the deterioration of position feedback controllability. In other words, the robot manipulator device of this embodiment starts position feedback control of each motor after bringing the initial position deviation within a target range. This makes it possible to obtain good controllability in the position feedback control of motors that require high speed tracking with a small amount of rotation (short control time).

In this embodiment, it is more preferable to reduce the effect of lost motion by performing a process to offset the backlash to one side as described in embodiment 1. Also, while there are applications such as material processing in which changing the trajectory near the start point is not permitted, in gripping and conveying systems, changing the trajectory near the start point among the trajectory from the start point to the end point of the drive is often permitted. For this reason, it is possible to use rewriting of the target trajectory in embodiment 2.

According to this embodiment, it is possible to improve the controllability of the motor used in the robot manipulator device and improve the stopping accuracy by absorbing the initial position deviation. By improving the stopping accuracy, it is possible to reduce the transition time to the next operation and improve the controllability of the next operation.
Other Examples
The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

The above-described embodiments are merely representative examples, and various modifications and variations are possible when implementing the present invention.

11 Motor 12 Rotational position detection unit 13 Drive waveform generation unit 14 Voltage gain setting unit 15 Target rotational position holding unit 16 Control unit 17 Initial position deviation adjustment unit 101 Stepping motor

Claims (16)

A detection means for detecting an actual rotational position of the motor;
a control means for performing a position feedback control on the motor so that the detected actual rotation position moves successively toward a plurality of target rotation positions when the motor is rotated in one direction ;
a processing means for performing a process for controlling an initial position deviation, which is a difference between the actual rotation position and a first target rotation position among the plurality of target rotation positions, within a predetermined range before starting the position feedback control,
the processing means performs, as the processing, a process of rotating the motor in the one direction or the reverse direction so that the actual rotation position approaches or coincides with the first target rotation position;
The motor control device is characterized in that the processing means changes at least some of the plurality of target rotation positions, including the first target rotation position, depending on the rotation direction of the motor in the processing. A detection means for detecting an actual rotational position of the motor;
a control means for performing a position feedback control on the motor so that the detected actual rotation position moves successively toward a plurality of target rotation positions when the motor is rotated in one direction ;
a processing means for performing a process for controlling an initial position deviation, which is a difference between the actual rotation position and a first target rotation position among the plurality of target rotation positions, within a predetermined range before starting the position feedback control,
The motor control device, wherein the processing means performs, as the processing, a process of changing the first target rotation position in the one direction or the reverse direction so that the first target rotation position approaches or coincides with the actual rotation position. The motor control device according to claim 1 or 2, characterized in that the processing means does not change some of the second and subsequent target rotation positions among the plurality of target rotation positions. The motor control device according to claim 2, characterized in that the processing means changes the first target rotational position among the plurality of target rotational positions, and changes at least some of the second and subsequent target rotational positions. A detection means for detecting an actual rotational position of the motor;
a control means for performing a position feedback control on the motor so that the detected actual rotation position moves successively toward a plurality of target rotation positions when the motor is rotated in one direction ;
a processing means for performing a process for controlling an initial position deviation, which is a difference between the actual rotation position and a first target rotation position among the plurality of target rotation positions, within a predetermined range before starting the position feedback control,
a first process for rotating the motor in one direction or the reverse direction so that the actual rotational position approaches or matches the first target rotational position, and a second process for changing the first target rotational position to the one direction or the reverse direction so that the first target rotational position approaches or matches the actual rotational position. The motor control device according to claim 5, characterized in that the processing means selects the first processing when the initial position deviation is greater than a first predetermined value, and selects the second processing when the initial position deviation is less than a second predetermined value. The motor control device according to claim 5, characterized in that the processing means selects and performs the first processing and then performs the second processing. The control means
generating a waveform of a drive voltage to be applied to the motor;
determining an output control amount using a position deviation between the actual rotation position and the target rotation position as an input;
8. The motor control device according to claim 1, wherein a voltage gain value for a drive waveform is controlled in accordance with the output control amount. The control means
Synchronizing a phase of the detected actual rotational position with a phase of the drive waveform;
9. The motor control device according to claim 8, wherein a predetermined phase difference is provided between the actual rotation position and the drive waveform. A motor;
a manipulator driven by the motor;
A robot manipulator apparatus comprising the motor control device according to any one of claims 1 to 9. detecting an actual rotational position of the motor;
performing a position feedback control on the motor so that the detected actual rotation position moves sequentially toward a plurality of target rotation positions when rotating the motor in one direction ;
a step of performing a process for, before starting the position feedback control, keeping an initial position deviation, which is a difference between the actual rotation position and a first target rotation position among the plurality of target rotation positions, within a predetermined range;
the step of performing the process of fitting the actual rotation position within the predetermined range includes, as the process, a process of rotating the motor in the one direction or the reverse direction so that the actual rotation position approaches or coincides with the first target rotation position;
A motor control method characterized in that the step of performing processing to keep the motor within the specified range changes at least some of the multiple target rotation positions, including the first target rotation position, depending on the rotation direction of the motor in the processing. A computer program that causes a computer to execute a process according to the control method described in claim 11. detecting an actual rotational position of the motor;
performing a position feedback control on the motor so that the detected actual rotation position moves sequentially toward a plurality of target rotation positions when rotating the motor in one direction ;
a step of performing a process for, before starting the position feedback control, keeping an initial position deviation, which is a difference between the actual rotation position and a first target rotation position among the plurality of target rotation positions, within a predetermined range;
A motor control method characterized in that the step of performing processing to keep the target rotation position within the specified range includes processing to change the first target rotation position in one direction or the reverse direction so that the first target rotation position approaches or coincides with the actual rotation position. A computer program that causes a computer to execute a process according to the control method described in claim 13. detecting an actual rotational position of the motor;
performing a position feedback control on the motor so that the detected actual rotation position moves sequentially toward a plurality of target rotation positions when rotating the motor in one direction ;
a step of performing a process for, before starting the position feedback control, keeping an initial position deviation, which is a difference between the actual rotation position and a first target rotation position among the plurality of target rotation positions, within a predetermined range;
a first process for rotating the motor in one direction or the reverse direction so that the actual rotation position approaches or matches the first target rotation position, and a second process for changing the first target rotation position in the one direction or the reverse direction so that the first target rotation position approaches or matches the actual rotation position. A computer program that causes a computer to execute a process according to the control method described in claim 15.