JPH0413107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a bilateral force-feedback type master-slave manipulator (automatic remote control device) that has extremely excellent force sensation transferability.

[Technical background of the invention]

BACKGROUND ART Conventionally, when working in environments with high radiation levels or high toxic gas concentrations, for example, master-slave manipulators have been used to perform the work in place of humans.

A master-slave manipulator operates a master hand in a place isolated from the work environment, and causes a slave hand installed at the work place to operate as if it were a human arm to perform work. Conventionally, such manipulators have been mechanical, using link mechanisms, wires, etc., but mechanical manipulators limit the distance between the operating section and the work area. Recently, manipulators that are exclusively controlled electrically have come to be used.

In an electric master-slave manipulator, all slave arm movements are performed by a motor provided on the slave side. Therefore, unlike the mechanical type, in this case, how faithfully the master side can feel the load force on the slave side as a force sensation is important in improving operational performance. Therefore, a bilateral master-slave manipulator has been considered as a device that can transmit such a force sensation relatively well. This bilateral method can be classified as follows:
It is roughly divided into symmetric type, force reversal type, and force feedback type.

In the symmetrical type, the slave side position adjuster and the master side position adjuster are controlled by the deviation (θ ₁ −θ ₂ ) between the master arm axis position θ ₁ and the slave arm axis position θ ₂ . In other words, the slave arm is given a torque in the direction of matching θ ₂ to θ ₁ , similar to a normal position servo system, and the master arm is given θ when θ ₁ is ahead of θ ₂ . The master side position adjuster applies torque in the direction of suppressing θ ₁ and bringing it closer to θ ₂ .

The force reverse type has a normal position servo system installed between the master arm and slave arm, detects the torque of the slave arm, and applies torque corresponding to the detected torque to the master arm. .

On the other hand, the force feedback type is equipped with a normal position servo system between the master arm and slave arm, and detects the master arm's torque and the slave arm's torque, respectively, and is designed to reduce the deviation between the two torques. It is equipped with a force servo system that applies torque to the master arm.

The symmetrical type uses so-called servo deviation, which simplifies the configuration of the servo system, but since it is difficult to accurately extract the servo deviation, it can only be applied to light load applications with light weight. . In addition, the force reverse type is suitable for heavy loads because it can apply torque to the master arm that corresponds to the torque applied to the slave arm. On the other hand, the force feedback type is equipped with a force servo system, so it is possible to apply a torque to the master arm that is equal to the torque applied to the slave arm, and can be applied not only in the case of light loads but also in the case of heavy loads. Applicable. Therefore, among the three methods, the force feedback type has the best force sensation transmission performance, can be applied to both light and heavy loads, and has the advantage that the operating force is small when no load is applied.

Incidentally, a force feedback type master-slave manipulator is normally constructed as shown in FIG.

That is, in FIG. 1, numeral 1 is a multi-jointed master arm installed in, for example, a remote control room, and 2 is a multi-jointed slave arm installed at a work place.

The master arm 1 has a master hand 3 for remote control at its tip, and a motor 5 for generating operating torque at its base end via a decelerator 4 and a position detector for detecting displacement of the master arm. 6. Further, a torque detector 7 for detecting the torque generated in the master arm 1 is installed near the decelerator 4 at the base end of the master arm 1 .

On the other hand, the slave arm 2 has a working slave hand 8 at its tip, and its base end connects to a motor 10 for driving the arm via a decelerator 9, and a position detector for detecting displacement of the slave arm 2. 11. Further, a torque detector 12 for detecting the torque generated in the slave arm 2 is provided near the decelerator 9 at the base end of the slave arm 2 .

In addition, 13 in the figure indicates the position detector 6 of each arm,
This is a subtracter which introduces the output signal from 11 and provides a deviation signal between these two output signals to the motor 10 via the amplifier 14. Further, reference numeral 15 in the figure introduces the output signals from the torque detectors 7 and 12 of each arm, and the deviation signal of these two output signals is input to the amplifier 16.
This is a subtracter that supplies the motor 5 via the subtracter.

The master-slave manipulator configured in this manner operates as follows.

That is, when the master hand 3 is now rotated by an angle θ _n , the position detector 6 on the master side detects this via the decelerator 4 and outputs a position signal θ _n . On the other hand, a position signal θ _s of the slave hand 8 is output from the position detector 11 on the slave side.
These position signals θ _n and θ _s are introduced into the subtracter 13,
These position error signals are provided to the amplifier 14 as a position error signal Δθ. The amplifier 14 drives the slave motor 10 based on this position deviation signal Δθ. The driving force generated thereby is transmitted to the slave arm 2 via the speed reducer 9, and the slave arm 2 is driven. This driving is continued until the position error signal Δθ becomes zero. As a result, the slave arm 2 follows the master arm 1.

When work by the slave arm 2 is started and a load torque T _s is generated on this slave arm 2,
This load torque T _s is detected by the torque detector 12 on the slave side. As a result, the torque detector 1
2 outputs a torque signal τ _s . On the other hand, from the master side torque detector 7, the master side torque signal τ _n
is being output. These torque signals τ _n and τ _s are inputted to a subtracter 15 and provided to an amplifier 16 as a torque deviation signal Δτ. amplifier 1
6 drives the motor 5 on the master side based on this torque deviation signal Δτ. The torque generated thereby is transmitted to the master arm 1 via the speed reducer 4. Therefore, the load torque T _s generated on slave arm 2 is the operating torque on master arm 1 side.
Feedback is given as T _n . As a result, the force sensation on the slave side can be transmitted to the master side.

By the way, in this type of master-slave manipulator, in order to make the master arm 1 and slave arm 2 smaller and lighter, and to simplify the structure,
Usually, various devices including torque detectors 7 and 12 are installed inside a motor box (not shown), that is, at the base end of each arm. Therefore, the torque detected by both arms is the torque generated at the base ends of both arms. However, the operating torque that we originally wanted to generate in master hand 3
T _n is the tip of the slave arm 2, as described later,
In other words, the load torque T _s on slave hand 8
It is.

In other words, if we consider that the rotation angles of master hand 3 and slave hand 8 are slightly increasing, and if we set dθ/dt≒0 and ignore the inertial force and viscous torque of each arm, then the operating torque on the master side T _n
The load torque T _s on the slave side is expressed by the following equations.

T _n = T _cn + n・T _tn + n・T _nn …(1) T _s = −T _cs −n・T _ts + n・T _ns …(2) Here, T _cn : Torque detector on the master side Friction torque between the master hand and the master hand T _tn : Friction torque between the master side torque detector and the motor T _nn : Generated torque of the master side motor T _cs : Friction torque between the slave side torque detector and the master hand T _ts : Friction torque T _ns between the torque detector and motor on the slave side : Torque generated by the motor on the slave side n : Represents the reduction ratio of the speed reducer, respectively. In addition, the motor 12 on the master side
_{The generated torque T nn of _ _ _ _ _ cs} ) ...(5). Here, k _n : conversion coefficient of the torque detector on the master side k _s : conversion coefficient of the torque detector on the slave side a: amplifier gain of the master side motor, respectively.

From the above equation, T _n can be expressed as follows.

T _n =nak _s /1+nak _n T _s +n/1+na
k _n T _tn +T _cn +nak _s /1+nak _n T _cs ……(6) Here, if k _n =k _s and nak _n ≫1, equation (6) becomes T _n =T _s +1/ak _n T _tn +T _cn + T _cs ...(7).

In this way, in the conventional master-slave manipulator, the operating torque T _n on the master side and the load torque T _s on the slave side do not match, as shown in the second to fourth terms on the right side of equation (7). The friction torque at each location where the load is applied is added to the load torque T _s to form the operating torque T _n on the master side.

In this way, in the conventional master-slave manipulator of this kind, when trying to make the arm smaller, simplify the structure, or increase the number of joints to increase the degree of freedom of the arm, the above-mentioned operation is difficult. torque
There was a problem in that the frictional torque at T _n increased and the force sensation was not transmitted accurately from the slave side to the master side, resulting in a decrease in operability.

Incidentally, such a problem also occurs in the symmetric type, and in order to deal with this problem, the master master is Detect the torque of the arm, differentiate this detection output, create a signal to eliminate the frictional force in the current direction of rotation based on this differentiated signal, and use this signal as an input to the position adjuster on the master side and slave side. is adjusted to compensate for the frictional force. However, what is shown in the above-mentioned publication is directed to a symmetrical type that is essentially not suitable for heavy loads. Further, the trigger for creating the compensation signal is obtained by using a signal obtained by differentiating the torque signal. Torque detectors use strain gauges that easily pick up noise, so their detection signals usually contain many noise components. Therefore, it is unreasonable to use this noisy signal, and it is difficult to improve the operability.

[Purpose of the invention]

The present invention has been made based on the above-mentioned problems, and its purpose is to apply it to a force feedback type device that inherently has excellent force sensation transmission performance and is highly versatile. It is possible to eliminate the influence of friction torque generated at the joints of each arm on the operating force without increasing the size of the arm and slave arm, complicating the structure, and without being affected by noise. It is an object of the present invention to provide a master-slave manipulator that can be operated and has extremely excellent operability.

[Summary of the invention]

The present invention includes a master arm, a slave arm, a master side torque detector that detects a load torque generated on the master arm at a base end of the master arm, and a master side torque detector that detects a load torque generated on the slave arm at a base end of the master arm. a slave-side torque detector that detects the position of the master arm at the base end of the slave arm; a master-side position detector that detects the position of the slave arm; and a slave-side position detector that detects the position of the slave arm; a master side motor that provides a master side motor, a slave side motor that drives the slave arm, and means that drives the slave side motor according to a deviation between an output of the master side position detector and an output of the slave side position detector; A bilateral servo comprising means for driving the master motor in accordance with a deviation between a slave torque signal that is the output of the slave torque detector and a master torque signal that is the output of the master torque detector. In a force feedback type master-slave manipulator, the speed and moving direction of the master arm are determined by differentiating the output signal of the master side position detector, and when the speed exceeds a predetermined value, the speed and movement direction of the master arm are determined. a master-side friction compensation signal generation means that outputs a compensation torque signal of a constant level with a polarity depending on the direction of movement; and a speed and movement direction of the slave arm are determined by differentiating the output signal of the slave-side position detector; slave-side friction compensation signal generating means for outputting a compensation torque signal at a constant level with a polarity corresponding to the moving direction of the slave arm from when the speed exceeds a predetermined value; a first means for adding the output signals of the master-side friction compensation signal generation means and outputting the result as a master-side torque signal; and subtracting the output signal of the slave-side friction compensation signal generation means from the output signal of the slave-side torque detector; a second means for outputting the signal obtained as a slave side torque signal, and driving the master side motor according to a deviation between an output signal of the second means and an output signal of the first means. equipped with the means.

〔Effect of the invention〕

According to the present invention, deviations in the torque signals output from the respective torque detectors are corrected using a torque compensation signal based on the friction torque unique to the device between the tip of the master arm and the tip of the slave arm. I have to. Therefore, by setting the value of the torque compensation signal according to the set position of each torque detector in each arm, the operating torque obtained at the tip of the master arm can be compared with the load torque generated at the tip of the slave arm. It is possible to make them almost match. In other words, friction torque can be canceled. Therefore, the operation section can obtain an operation torque that is very close to the actual force sensation, and the operability can be greatly improved. and,
In particular, in the present invention, the master side friction compensation signal generating means and the slave side friction compensation signal generating means differentiate the output signals of the master side position detector and the slave side position detector, respectively, and detect the speed and moving direction of each arm. However, since a compensation torque signal of a fixed level is outputted based on the detection result, a stable compensation operation can be performed. That is, since the position detector, as typified by a voltage-dividing resistor type potentiometer, can have a large output level, the proportion of noise components contained in its output signal is extremely small. For this reason,
By obtaining a differential signal that accurately corresponds to the movement of each arm using the master-side friction compensation signal generation means and the slave-side friction compensation signal generation means, the transmission of the compensation torque signal can be started and Possible to switch polarity. Therefore, not only can the overall configuration be simplified, but also a stable compensation operation can be performed.

[Embodiments of the invention]

An embodiment of the present invention will be described below. Second
The figure shows a force feedback bilateral servo type master-slave manipulator according to this embodiment, and the same parts in FIG. 3 as in FIG. 2 are given the same reference numerals. Therefore, we will omit redundant explanations.

The master-slave manipulator according to this embodiment differs from the conventional one in that a friction compensating means for canceling the friction torque generated in the master arm 1 and slave arm 2 is newly provided.
That is, reference numerals 21 and 22 in the figure are friction compensation circuits that generate compensation torque signals T _Bn and T _Bs commensurate with the friction torque generated in the master arm 1 and slave arm 2, respectively. Further, 23 in the figure is an adder that adds the compensation torque signal T _Bn output from the master side friction compensation circuit 21 and the torque signal τ n output from the master side torque detector 7, and 24 is an adder for adding the compensation torque signal T Bn output from the master side friction compensation circuit 21 and the torque signal τ _n output from the master side torque detector 7. This is a subtracter that generates a difference signal between the compensation torque signal T _Bs output from the friction compensation circuit 22 and the torque signal τ _s output from the slave side torque detector 12. These adder 23 and subtracter 2
4 constitutes means for modifying the torque signal with a compensation torque signal.

In this embodiment configured as described above, if the output signal from the adder 23 is τ _n ′ and the output signal from the subtracter 24 is τ′ _s , then the torque generated by the motor 5 on the master side is T _nn is T _nn =a(τ′ _s −τ′ _n ) ……(8). Here, τ′ _n = k _n (T _n −T _cn ) + T _Bn ……(9) τ′ _s = k _s (T _s + T _cs ) + T _Bs ……(10). Using equations (8) to (10) above and equation (1) above, the operating torque T _n on the master side can be expressed as follows.

T _n =nak _s /1+nak _n T _s +n/1+nak _n T _tn +T _cn +nak _s /
1+nak _n T _cs −na/1+nak _n T _Bn −na/1+nak _n T _Bs ……
(11) Here, if k _n = k _s , nak _n ≫ 1, equation (11) becomes T _n = T _s +1/ak _n T _tn + (T _cn -1/k
_n T _Bn ) + (T _cs -1/k _n T _Bs )...(12). In equation (12), a and k _n are the master side amplifier 22 and torque detector 1, respectively.
4 and is a constant. In addition, since the inertial force and viscous resistance of each arm can be almost ignored, the friction torque of each arm T _tn , T _cn ,
T _cs also becomes a constant and a value unique to each arm. Therefore, if the compensation torque signals T _{Bn and} T _Bs are set so that, for example, T Bn = k _n T _cn ... (13) T _Bs = k _n T _cs ... (14), then T _n = _{T s +} 1/ ak _n T _tn ...(15) Therefore, the friction torque of both arms can be considerably reduced. Furthermore, if we go further and set the compensation torque signal T _Bn so that T _Bn = k _n T _cn + 1/aT _tn ... (16), then T _n = T _s ... (17), and both arms The friction torque can be almost completely canceled out.

Next, a specific example of the configuration of the friction compensation circuits 21 and 22 will be described.

FIG. 3 is a diagram showing an example in which the friction compensation circuits 21 and 22 are configured by a differentiation circuit 31 and a friction compensation function generation circuit 32. That is, for example, the position signal θ _n output from the position detector 13 is
is differentiated by and becomes the speed signal υ _n . This speed signal υ _n
is introduced into the friction compensation function generation circuit 32. The friction compensation function generating circuit 32 generates a polarity constant T _Bn according to the direction of movement of the arm when the speed exceeds a predetermined speed.
is output as a compensation torque signal. This constant T _Bn
For example, before operating the manipulator, the size of
It is adjusted in advance so as to satisfy the relationship shown in equation (13) or equation (16). On the other hand, on the slave side, the compensating torque signal T _Bs is
is generated.

In this manner, according to the present embodiment, the movement of the master arm 1 is detected by the differentiating circuit 31, and a compensation torque signal T _Bs having a polarity corresponding to the direction of movement is obtained. Therefore, if the compensation torque signal T _Bs is set to a value corresponding to the frictional torque generated in each arm, that is, the right-hand side of equation (13) or (16), the above-mentioned effect can be obtained and the operation becomes extremely easy. It is possible to provide a master-slave manipulator with excellent performance.

Note that the present invention is not limited to the above embodiments. For example, the friction compensation circuits 21 and 22 may be configured as shown in FIG. In other words, this circuit is obtained by adding an auxiliary function circuit 33 and a switch 34 to the circuit shown in FIG. The auxiliary function circuit 33 is a circuit that outputs an alternating signal such as a sine wave, a rectangular wave, a trapezoidal wave, etc. of several Hz with a peak value T _Bn , for example. The switch 34 selects the output from the auxiliary function circuit 33 when the speed signal υ _n output from the differentiating circuit 31 is zero, that is, when each arm is stationary, and when the speed signal υ _n is not zero, That is, when each arm is moving, it operates to select the output from the friction compensation function generating circuit 32.

With such a configuration, it is possible to compensate for the frictional torque even when starting the master arm, and the cold feeling at the time of starting is eliminated.

As described above, the present invention can be implemented with various modifications without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a conventional bilateral servo type force feedback type master slave manipulator, and FIG. 2 is a bilateral servo type force feedback type master slave manipulator according to an embodiment of the present invention. FIG. 3 is a block diagram showing a schematic configuration of the manipulator, FIG. 3 is a block diagram of a friction compensation circuit in the same manipulator, and FIG. 4 is a bilateral servo type force feedback type master-slave manipulator according to another embodiment of the present invention. FIG. 3 is a diagram showing a friction compensation circuit in FIG. 1...Master arm, 2...Slave arm,
3...Master hand, 4,9...Decelerator, 5,1
0...Motor, 6,11...Position detector, 7,1
2...Torque detector, 8...Slave hand, 1
3, 15, 24...Subtractor, 14, 16...Amplifier, 21, 22...Friction compensation circuit, 23...Adder, 31...Differential circuit, 32...Friction compensation function generation circuit, 33... Auxiliary function circuit, 34... switch.

Claims (1)

[Claims] 1 A master arm, a slave arm, a master side torque detector that detects the load torque generated on the master arm at the base end of the master arm, and a master side torque detector that detects the load torque generated on the slave arm at the base end of the slave arm. a slave side torque detector that detects the position of the master arm; a master side position detector that detects the position of the slave arm; and a master side that applies force to the master arm. a motor, a slave-side motor that drives the slave arm, means for driving the slave-side motor in accordance with a deviation between the output of the master-side position detector and the output of the slave-side position detector, and the slave-side motor. A bilateral servo type force comprising: means for driving the master side motor according to a deviation between a slave side torque signal that is an output of a torque detector and a master side torque signal that is an output of the master side torque detector. In the feedback type master-slave manipulator, the output signal of the master-side position detector is differentiated to determine the speed and movement direction of the master arm, and when the speed exceeds a predetermined value, the movement direction of the master arm is changed. A master-side friction compensation signal generating means outputs a compensation torque signal of a constant level with a corresponding polarity, and the output signal of the slave-side position detector is differentiated to determine the speed and moving direction of the slave arm, slave-side friction compensation signal generating means for outputting a compensation torque signal at a constant level with a polarity corresponding to the moving direction of the slave arm when the value exceeds the slave arm; a first means for adding the output signals of the signal generating means and outputting the result as a master side torque signal; and a first means for adding the output signals of the signal generating means and outputting the resultant signal as a master side torque signal; and means for driving the master motor in accordance with the deviation between the output signal of the second means and the output signal of the first means. A master-slave manipulator characterized by: