JPH071464B2 - Positioning device - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention is a device that is connected to a sequence controller or the like and is provided with position data and speed data from the device to position the movable shaft at a commanded target position. The present invention relates to a positioning device that handles an operated position as an absolute position.

[Prior art]

Conventionally, when controlling the position and speed of a movable shaft by a control device such as a sequence controller, positioning is performed between the control device and the drive device for the movable shaft so as to reduce the burden on the control device and facilitate control. The device is interposed. Some such positioning devices use an absolute position signal output from the absolute position detection device at a fixed cycle as a position feedback signal from the movable shaft. A positioning device based on such an absolute position is based on the position and command speed commanded by a control device such as a sequence controller.
The control target position of the movable axis at the interpolation point is generated at regular time intervals, and the output from the absolute position detection device is input as the absolute position of the movable axis at that time, and the magnitude corresponding to the deviation from the control target position is input. By outputting a speed signal to the drive device, the position of the movable shaft is made to follow the interpolated control target value successively.

[Problems to be Solved by the Invention]

The absolute position detection device samples the absolute position represented by the angle of the movable axis and the like at a constant cycle and performs arithmetic processing (hereinafter, the timing of detecting the absolute position is referred to as "detection timing") and determines the absolute position signal. It outputs to the positioning device in a cycle. Therefore, the value output from the absolute position detection device, the detection timing P _1, P _2, P ₃ current absolute true movable axis ...... position (hereinafter referred to as "current position") discrete representation of the Then, as shown by the curve A in FIG. 3 with respect to the time axis, it changes stepwise at a constant period Tr. On the other hand, the control target position generated by interpolating the positioning position changes stepwise with a constant period Ti as shown by the curve B in FIG. 3 with respect to the time axis. Then, the deviation between the control target position and the current position, that is, the tracking deviations Δ ₁ , Δ ₂ , Δ _3, ...
At t ₁ , t ₂ , t _3, ... (Hereinafter referred to as “control timing”), each is calculated, and a speed signal corresponding to the tracking deviation is output to the drive device at that time. However, in the conventional device, the detection timing of the absolute position of the movable axis by the absolute position detection device and the control timing by the positioning device are controlled by independent clocks, respectively, and they are asynchronously controlled. there were. That is, the detection cycle Tr of the current position in FIG.
And the control cycle for generating the control target position and detecting the speed signal
Ti was not equal. For this reason, since the time delay of the control timing with respect to the detection timing changes without being constant, the tracking deviation includes a component that changes due to the fluctuation of this time delay. By the way, when the movable axis is controlled at a constant speed by changing the control target position at a constant speed, ideally, the current position of the movable axis is accurately and with a certain time delay with respect to the control target position. It is desirable to follow, so the tracking deviation Δ
Is constant regardless of time, and it is desirable that the speed signal and the actual speed of the movable shaft are also constant. However, since the detection period Tr and the control period Ti are not equal to each other, as compared with the control timings T ₃ and T ₄ , the control target position changes to the value of the next control timing, but the absolute position detection is performed. The current position output by the device may not change. Then, the tracking deviation Δ ₄ calculated at time t ₄ is apparently large, and a large speed signal is output. Therefore, the movable shaft is accelerated and the speed is increased.
However, since the control target position changes at a constant speed, the tracking deviation becomes smaller than the ideal value and the movable shaft is decelerated at another control timing. In the end, the speed of the feasible axis causes the beat of the frequency difference between the detection period Tr and the control period Ti, the servo system becomes unstable, and noise is generated. The present invention has been made to solve the above problems, and an object thereof is to stabilize a servo system.

[Means for solving problems]

The configuration of the invention adopted to solve the above problems is as follows. That is, the present invention generates an interpolated control target position at that time from a target position that is a commanded positioning target and a commanded speed, and determines the absolute position of the movable axis at regular time intervals. An absolute position signal is input from an absolute position detection device that calculates in cycles, and the movable axis is driven at a command speed according to the deviation between the absolute position input from the absolute position detection device and the interpolated control target position. In the positioning device for positioning the movable shaft at the commanded target position by outputting the speed signal to the driving device, the absolute position signal output from the absolute position detection device at the time of completion of calculation is input as an interrupt signal. Then, every time the signal is input, the control of the positioning device is started,
The control of the positioning device is synchronized with the cycle of absolute position detection of the absolute position detection device.

[Action]

The control of the positioning device is started each time an absolute position signal output from the absolute position detection device upon completion of calculation is input as an interrupt signal, and the signal is input. Therefore, the positioning control is synchronized with the absolute position detection cycle, and
It is executed after a fixed time from the detection timing. Therefore, since the control timing with respect to the absolute position detection timing has a constant and constant time delay, the tracking deviation stabilizes at a constant value during constant speed driving. Therefore, the speed of the movable shaft also stabilizes at a constant value, and stable servo control can be obtained.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a device using a positioning device according to an embodiment of the present invention. In FIG. 1, A is
A positioning device, B is a servo unit, and C is an absolute position detection device. The positioning device A mainly includes a microprocessor unit 1 (hereinafter abbreviated as "MPU") for performing control calculation, a ROM 2 storing a control program thereof, a data input device 3 such as a keyboard, and a battery-backed RAM 4. A positioning data table (PD) in which the position number and position data for each of a plurality of predetermined positioning points and speed data for designating the moving speed to each point are stored in the RAM4.
T) has been formed. Also, each time the current position of the movable base 10 is detected, this value is stored in the current position register APR that stores this value.
Are formed. The ROM 2 stores a control program for calculating a tracking deviation at regular time intervals and outputting a speed signal to the register 5. The servo unit B is mainly composed of a register 5, a DA converter 7 and a drive circuit 8. The speed signal S1 output from the MPU1 is input to the register 5, converted into an analog signal by the DA converter 7, and output to the drive circuit 8.
The drive circuit 8 inputs this signal and supplies power to the servo motor 9 to rotate it. A feed screw 11, which is a movable shaft for moving the movable base 10, is mechanically connected to the output shaft of the servomotor 9. Therefore, the absolute position of the movable shaft can be regarded as corresponding to the absolute position of the movable base 10. Further, the output shaft of the servo motor 9 is provided with a speed detector 12 which detects the moving speed of the movable table 10 and sends a speed feedback signal to the drive circuit 8. The absolute position detecting device C mainly includes a first resolver 13 mechanically coupled to the output shaft of the servomotor 9 and a second resolver 13 coupled to the first resolver 13 via a reduction mechanism 14. 15, the resolver excitation circuit 16, and the first resolver
A first phase comparison circuit 17 for detecting the phase angle of 13, a second phase comparison circuit 18 for detecting the phase angle of the second resolver 15, and an absolute position for calculating the absolute position of the movable table 10 from the outputs of both. It comprises a detection circuit 19 and a real-time clock (hereinafter abbreviated as "RTC") 20 which drives the circuit 19 at a constant cycle and gives an absolute position detection timing. First resolver 1
3 shows that when the feed screw 11 makes one revolution, its input shaft makes one revolution,
Moreover, the second resolver 15 is configured such that its input shaft makes one rotation while the movable table 10 moves from one end of the moving range to the other. The phase difference between the output voltage of the resolver and the excitation voltage changes according to the rotation angle of the input shaft. The first phase comparison circuit 17 counts the phase difference of the output voltage of the first resolver 13 with respect to the excitation voltage by a counter, converts it into a digital value, and outputs it to the absolute position calculation circuit 19.
Similarly, the second phase comparison circuit 18 converts the phase difference between the output voltage of the second resolver 15 and the excitation voltage into a digital value and outputs it to the absolute position calculation circuit 19. As shown in FIG. 4, the standing position calculation circuit 19 is activated each time the detection timing signal D is input from the RTC 20 at the timing of the time W1 (FIG. 2), and the phase data is output from both phase comparison circuits 17 and 18. (Steps 300 and 302), calculate the absolute position of the movable base 10 (3
04) and output (306) to the MPU1 via the interface circuit (IF). Further, when the absolute position calculation circuit 19 completes the calculation of the absolute position data, it outputs an interrupt signal S2 giving the output timing of the data to the interrupt input terminal (NM1) of MPU1 at the timing of time U1. As will be described later, when the MPU1 receives the interrupt signal S2, the MPU1 starts executing a program for predetermined follow-up control and outputs a speed signal. The interrupt signal S2 is a signal delayed by a certain time from the detection timing signal D output from the RTC 20 (Fig. 2). Reference numeral 6 is a known stored program type sequence controller which sends a position number to be positioned according to a predetermined process to the MPU 1 through an interface circuit (IF). Next, the operation of the apparatus of this embodiment will be described based on the flowcharts shown in FIGS. The positioning data is stored in advance in the RAM 4 by the data input device 3.
It is entered in the positioning data table PDT inside. The program of FIG. 5 is started when the position number of the positioning point is input from the sequence controller 6. When the position number is input, the positioning data table PDT is searched and the positioning data corresponding to the position number is read (100). Next, the initial remaining movement amount L0 is calculated and stored by subtracting the current position R of the movable table 10 stored in the current position register APR from the positioning target position M just read out (102). . In this way, each time the position number is entered, the initial remaining movement amount L0
After setting, interrupt signal from absolute position calculation circuit 19
The program of FIG. 6 is executed each time S2 is input.
First, in step 200, the absolute position detected by the absolute position calculation circuit 19 is stored in the current position register APR as the current position R of the movable table 10. Next, the target position M of the positioning point
Is read, the current position R is subtracted from the target position M, and the actual remaining movement amount RL is calculated (202, 204). Next, a zero determination of the actual remaining movement amount RL is performed, and if it is not zero, the movement amount of the control target position of the movable table 10 with respect to the positioning target position M at the control timing interpolating the path to the positioning point This movement amount is called "theoretical remaining movement amount") IL
Is calculated (208). At this time, the interpolated control target position is generated by performing processing such as gradual acceleration and gradual deceleration from the target position M and the commanded speed. Next, the deviation ΔL of the actual remaining movement amount RL from the theoretical remaining movement amount IL is calculated (21
0). Then, the speed signal Vc according to the deviation ΔL is calculated and output to the register 5 at the control timings t ₁ , t _2, ... (212, 214). Then, by the action of the servo unit B, the servo motor 9 is rotated at the command speed. Such processing is repeatedly executed in step 206 until the actual remaining movement amount RL becomes zero. When it is zero, zero is output as the speed signal Vc (218). As a result, the absolute position of the movable base 10 converges to the positioning target position and is finally positioned at the target position M while following the changing interpolated control target position in synchronization with the control timing. In the above process, the detection timing at which the current position of the movable table 10 is detected by the absolute position detection device C is RTC20.
By this, it is precisely controlled in 2ms cycle. Therefore, the interrupt signal S2 to MPU1 will also be exactly 2ms,
The control timing for 1 to calculate the tracking deviation and output the speed signal is also exactly 2 ms. Therefore, the control timing is only delayed by a fixed and constant time with respect to the detection timing. Therefore, when the interpolated control target value changes at a constant speed, the tracking deviation becomes constant, and the speed of the movable table 10 also becomes constant. Therefore, the instability of the servo system is improved.

【The invention's effect】

As described above, according to the present invention, the interpolated control target position at that time is generated, and its value is followed by the absolute position input from the absolute position detection device that calculates the absolute position of the movable axis in a fixed cycle. In a positioning device that calculates the deviation and outputs a speed signal of a magnitude corresponding to the deviation, input the absolute position signal output from the absolute position detection device at the completion of calculation as an interrupt signal, and input that signal each time. , The control of the positioning device is started, and the control of the positioning device is changed to the absolute position detection cycle of the absolute position detection device.
It is characterized by making it periodic. Therefore, since the absolute position detection timing and the control timing for outputting the speed signal are synchronized with a constant phase difference, if the interpolated control target position changes at a constant speed, the tracking deviation Becomes constant, the speed signal also becomes constant, and the moving speed of the movable shaft becomes constant. Therefore, the instability of the servo system, which has been observed in the conventional asynchronous control, is improved, and the generation of noise due to it is prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a movable table control device using a positioning device according to a specific embodiment of the present invention, and FIG. 2 is a timing chart explaining the operation of the device of this embodiment, FIG. 3 is a timing chart for explaining the operation and drawbacks of the conventional apparatus, FIG. 4 is a flow chart showing the operation of the absolute position calculation circuit, and FIGS. 5 and 6 respectively constitute the apparatus of the embodiment. It is the flowchart which showed the processing procedure of MPU. 1 ... Microprocessor unit, 9 ... Servo motor, 10 ... Moving base, 11 ... Feed screw, 13 ... First resolver, 15 ... Second resolver

Front page continuation (72) Inventor Koji Hasegawa 1-1 Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (72) Inventor Hideki Sato 1-1-1 Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (72) Inventor Shoji Igawa 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Katsutoshi Naruse 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor, Yasutoku Sugito Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor, Masashi Ito Toyota Town, Toyota City Aichi Prefecture, Toyota City, Toyota (72) Inventor Hideki Hayashi 1-chome Kita-Otsuka, Toshima-ku, Tokyo No. 15-1 Sanyo Electric Co., Ltd. (72) Inventor Johei Yamamoto 1-15-1 Kitaotsuka, Toshima-ku, Tokyo Sanyo Electric Co., Ltd. (56) Reference JP-A-55-32197 (JP, A) ) JP-A-54-150575 (JP, A) JP-A-61-114304 (JP, A) 61-285510 (JP, A) JP-A-51-87686 (JP, A) JP-A-61-65303 (JP, A)

Claims (1)

[Claims] 1. A control target position interpolated at a given time is generated from a target position, which is a commanded target for positioning, and a commanded speed, and the absolute position of a movable axis is set at a constant cycle at regular time intervals. An absolute position signal is input from the absolute position detection device that is calculated by, and the movable axis is driven at a command speed according to the deviation between the absolute position input from the absolute position detection device and the interpolated control target position. In a positioning device that positions the movable shaft at the commanded target position by outputting a speed signal to a drive device, the absolute position signal output from the absolute position detection device at the time of completion of calculation is input as an interrupt signal. , Each time the signal is input, start the control of the positioning device,
A positioning device, wherein control of the positioning device is synchronized with a cycle of absolute position detection of the absolute position detection device.