JPS5932275B2 - Master/slave type servo manipulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the load torque on the slave (driven) side is
This invention relates to a force-reflecting servo manipulator that returns force to the operator who controls the main drive side.

Conventional manipulators are composed of a drive-type servo mechanism (bilateral servo mechanism), but conventional drive-type servo mechanisms transmit position or angle deviation signals of the master axis and slave axis, as well as speed deviation signals of both axes. Although it is returned to the master and slave sides, a large torque is required to operate the master shaft even if the slave shaft load torque is zero due to the friction and viscous resistance present in the servo system. As an improved servo manipulator, a signal corresponding to the position or angle deviation of the master axis and slave axis is returned to the master side and the slave side, respectively, and a signal corresponding to the torque of each axis is sent back to the master side and the slave side respectively. The applicant has already proposed a servo manipulator that improves maneuverability and workability by returning to the original position. The present invention provides the above-mentioned force reflection type servo manipulator, in which the torque signal feedback system on the master side is provided with a bias circuit that can apply a DC bias superimposed on the torque signal in one direction of the master shaft. It is an object of the present invention to provide a servo manipulator that further improves maneuverability and workability by applying a bias superimposed on the operating force of an operator to the opening operation in a direction operation, for example, an opening/closing operation of a finger section.

FIG. 1 is a block diagram of one joint showing an embodiment of the present invention.

When the operator rotates the master shaft 11 in a certain direction,
An angular deviation signal ε between the master axis and the slave axis 12 generated by the operation is detected by comparing the detected angles θ1 and θ2 of the respective angle detectors 21 and 22. This signal ε is the torque signal εt1 of the torque detector 31 provided on the master shaft 11.
The servo amplifier 41 amplifies the difference between the
1 drive voltage. Similarly, on the slave side, the difference between the signal ε and the torque signal εT2 of the torque detector 32 provided on the slave shaft 12 is applied to the servo motor 52 via the amplifier 42. With this basic configuration, a voltage is applied to the servo motor 51 on the master side in a direction to stop the rotation given by the operator, and the same voltage is applied to the servo motor on the slave side in a direction to accelerate the rotation. The angular displacement applied to the master shaft 11 is faithfully reproduced on the slave shaft 12, and the operator operating the master shaft 11 can feel the force corresponding to the load on the slave shaft 12. Also,
The torque feedback by the torque detectors 31 and 32 reduces the friction and viscous resistance force existing in the servo system, making it similar to working directly on an object. Here, master axis 1
For rotation in a certain direction of 1, the torque signal ε, 1 of the torque detector 31 is directly compared with the signal ε, and for rotation in the opposite direction, a DC bias Vb is superimposed on the signal εt1 to compare the signal ε with the signal ε. A bias circuit 6 for comparison is provided in the torque signal feedback system on the master side.

As a result, when operating the master axis in a certain direction, the same control force as before is required, and when operating the master axis in the opposite direction, a weak control force is required.
Therefore, for example, if the target joint is a finger, the force in the opening direction of the human finger is much smaller than that in the closing direction.
In addition, since effective work is often performed by movement or force in the direction of closing the finger, effective work is performed without biasing the torque signal for the work of closing the finger, and after the work is completed, the finger is closed. When opening, a bias is superimposed on the torque signal to enable work with light torque or work using only the bias circuit. The fact that such control becomes possible will be explained below.

In FIG. 1, when the bias voltage Vb is not applied, the angle difference signal ε and the torque detection signals εTl and εT2 are expressed by the following equations. However, kθ is the generated voltage coefficient of the angle detectors 21 and 22, Kf is the generated voltage coefficient of the torque detectors 31 and 32, θ1 is the angular displacement of the master shaft 11, θ2 is the angular displacement of the slave shaft 12, and T1 is the angular displacement of the slave shaft 12. The torque T2 applied to the master shaft 11 is the load torque of the slave shaft 12.

In the above equation, if the amplification factors of the servo amplifiers 41 and 42 and the generated voltage coefficient Kf of the torque detectors 3 and 32 are sufficiently large, the friction and viscous resistance of the servo system can be ignored, and
T, and T2 almost match.

In other words, the larger the amplification factor of the servo amplifiers 41, 42 and the generated voltage coefficient Kf of the torque detectors 31, 32, the smaller the influence of friction and viscous resistance on the servo system, but in order to keep the system stable, Since the amplification factor and the generated voltage coefficient Kf must be suppressed to certain finite values, this influence cannot be completely eliminated. Next, bias voltage Vb
When , the DC bias voltage Vb is inserted into the master side local feedback loop, and the slave shaft torque becomes .

In other words, even if the torque T1 on the master side is zero, the slave axis V
It generates a torque of b/Kf and rotates until it is balanced with the load torque. It goes without saying that the master axis also rotates as the slave axis rotates. FIG. 2 shows a specific embodiment in which the opening operation of the fingers is performed not by the operator's steering torque T1 but by the bias voltage Vb generated by the operation of the bias circuit 6. As shown in FIG.

In the figure, when the operator operates the lever 7 on the master side, the torque T1 at that time is detected by the torque detector 31 using a strain gauge, and the angular displacement θ1 is detected by the potentiometer 21. The finger section 8 on the slave side uses a four-bar link mechanism to convert the rotational motion of the slave shaft 12 into parallel motion, and its grasping force and opening degree are detected as T2 and θ2 by the torque detector 32 and potentiometer 22 on the rotating section. be done. 91 and 92 are signal amplifiers, and 10, 111 and 112 are differential amplifiers.

Reference numerals 41 and 42 are power amplifiers using power transistors, which drive the servo motors 51 and 52.

The switch 61 of the bias circuit 6 is installed very close to the operator 10, and when it is turned to the DC voltage side, torque is generated in the direction of opening both the slave side finger 8 and the master side finger lever 7. In Fig. 2, servo motor 5
1, 52, reducer 121, 122 and torque detector 31
, 32 can be replaced with a servo valve, a hydraulic motor, and a pressure detector, respectively, to form an electro-hydraulic servo mechanism. FIG. 3 shows a method for generating the DC bias voltage b when the torque detector 31 is constituted by a strain gauge.

A method is already well known in which a bridge is configured with four strain gauges and the gauges are installed to detect a minute strain or a torque or force proportional to the strain.

In this example, when the master shaft torque T1 is zero, if the switch 61 in FIG. 3 is open, the four strain gauges 13 to 16
As the resistance values Rl, R2, R3, and R4, RlR4=R2
Since it is R3, the voltage e between points A and b is also zero. Next, switch 6 is closed, and a resistor R whose value is relatively larger than the resistance value of the gauge is connected in parallel with gauge 15. When inserting, the torque T1
Even though is zero, the balance of the bridge is disrupted and a DC bias voltage is generated.

This value corresponds to Vb in FIG. 2, and generates a torque in the direction of opening the fingers. In this method, even if the torque detection part surrounded by the broken line is provided very close to the lever 7 in FIG. A feature is that the required bias voltage Vb can be generated without increasing the signal line.
Note that the switch 61 is a resistor R. strain gauge 1 in parallel with
5 may be connected in series. Fig. 4 shows a torque detector consisting of a spring 17 and a potentiometer 18 for detecting its displacement. .

By inserting a resistor and closing the switch 61, it is possible to obtain a change in the output voltage e corresponding to the bias voltage Vb in FIG. 2, and it has the same characteristics as the case in FIG. 3. Also in this case, resistor R is connected to one terminal of the potentiometer. The switch 61 and the switch 61 can be connected in parallel. As described above, the servo manipulator according to the present invention includes a bias circuit with a small number of parts consisting of a switch and a resistor for the torque detection signal of the master side joint, so that it is superimposed on the torque signal to reduce or reduce the steering torque in one direction. It is possible to perform operations that do not require a control torque, and it is possible to provide a manipulator that is adapted to the control function of the operator.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figures are diagrams showing specific embodiments of the present invention, Figures 3 and 4.
The figure is a circuit diagram showing an embodiment of the bias circuit in the present invention. 1 bis 7 star axis, 12゜゜slave axis, 21 quantity 22
... Angle detector, 31, 32 ... Torque detector, 4
1, 42... Servo amplifier, 5, 52... Servo motor, 6... Bias circuit, 61... Switch.

Claims (1)

[Scope of Claims] 1. A detection means for detecting a signal according to the position or angular deviation between the master axis and the slave axis, a pair of torque detectors for detecting the torques of the master axis and the slave axis, respectively, and a pair of torque detectors for detecting the torque of the master axis and the slave axis, respectively, a bias circuit that applies a DC bias by superimposing the torque detection signal of the torque detector in one direction on the torque detection signal of the master shaft in one direction; and a torque detection signal of the master shaft that passes the detection signal of the detection means and the bias circuit; a first amplifier that amplifies the deviation between the detection means and the drive voltage of the servo motor that drives the master axis; and a servo that amplifies the deviation between the detection signal of the detection means and the torque detection signal of the slave axis to drive the slave axis. A master/slave type servo mapululator, characterized in that it is equipped with a second amplifier for providing a driving voltage for a motor. 2. In claim 1, the bias circuit is characterized in that a resistor can be connected in series or in parallel to one of the torque detectors of the master shaft in which the strain gauges are bridge-connected. Master slave type servo manipulator. 3. In claim 1, the bias circuit is configured to connect a master shaft torque detector using a potentiometer that changes a rotation angle according to the torque of the master shaft between the output terminal of the potentiometer and another terminal. A master slave type servo manipulator characterized by a configuration in which resistors can be connected in series or in parallel.