JPS60254209A - Robot control system - Google Patents

Abstract

PURPOSE:To control both the power and the position of a robot hand by detecting the power applied to an actuator by a power detector, etc. and using the present position of a position detector and the sum added with the prescribed weight as a basic control amount. CONSTITUTION:A robot 1 has a hand 1a at its tip part, arms 1b-1e that actuate the hand 1a and a base 1f. The hand 1a is moved by an actuator. Each actuator contains position detectors 21 and 22, and outputs (p) and p1 of these detectors are supplied to a signal processing circuit 3 for detection of the power and the position of the robot 1. Thus the detected position (p) of the detector 22 is obtained together with the detection power (f), i.e., the difference between both detectors 21 and 22. These positions (p) and the power (f) are supplied to a computer 4 to monitor the working state of the robot 1 as well as to deliver a target command position p0, the target command power f0 and the 1st and 2nd weights (a) and (b). Based on these outputs, a controller 5 controls the drive current of each actuator so that (y) in an equation I is set at zero (DELTAp and DELTAf are shown by equations II and III respectively).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a robot control method that controls the actuators of a robot using position and force information, and in particular, the present invention relates to a robot control system that controls the actuators of a robot using position and force information, and in particular, it is possible to easily change the control form and adapt to the work. Concerning flexible robot control methods.

In recent years, robots have been developed to automate tasks performed by humans, and efforts are being made to control robots to perform operations equivalent to human hands and arms.

If robots can perform tasks similar to those performed by human hands and arms, they will be able to perform more advanced tasks and be extremely convenient.

In general, robot control is based on position control of an actuator (arm), and a work hand at the tip of the arm is positioned at a commanded position to perform work.

Such positional control alone is insufficient to allow the robot to perform functions equivalent to those of a human arm or hand, and is not adaptable to tasks that are influenced by other objects.

For this reason, the force exerted by the actuator (or the reaction force from the outside)
It is necessary to detect and control the actuator.

[Conventional technology]

Conventionally, force is controlled by giving a certain rigidity to the actuator for position control, setting a virtual target value first, and creating a certain deviation between the virtual target value and the current value. , a method of outputting force is known.

In addition, in the case of a device equipped with a force detection function, a method such as converting the detected force into a deviation and subtracting it from a virtual target value is used.

[Problem that the invention seeks to solve]

On the other hand, human arms and hands have the necessary force control function and tactile function in addition to the positioning function, so it is necessary to equip the robot with these functions and use these functions at the appropriate time according to the work. . For example, to fit two members together, jl! is applied to one member in a fixed position. ! After the two members are positioned by the robot and further accurately aligned using the tactile function, the two members are pressed together by a predetermined force.

Therefore, in the conventional control method using a tactile sensor, one member is controlled to follow the other.
In pressing, it is necessary to change the control mode in order to control the force, and in addition to the problem that the change is complicated, the position accuracy itself is also affected because the tactile sensor deforms to some extent to detect the force. There was also the problem that it was not expensive because it could not have rigidity.

Also, since force is given by the product of stiffness and positional deviation,
If the rigidity is large, even a small deviation will generate a large force. Therefore, the rigidity cannot be increased too much. However, if the rigidity is low, it is easy to vibrate and cannot be driven at high speed.

Furthermore, it is susceptible to disturbances such as gravity and has poor positioning accuracy. Therefore, handling of car position combined control is complicated, and detailed control cannot be performed.

For this reason, in conventional robot control methods, position control,
Although it is possible to perform both force control, there is a problem in that it is difficult and complicated to change the control mode.

[Means for solving problems]

An object of the present invention is to provide a control method for a robot that can easily change control modes based on position and force information.

Therefore, in the first aspect of the present invention, an actuator having a detector for detecting force and position, an actuator in which a first weight is attached to the difference between a command force and a detection force of the detector, and a command control means for driving and controlling the actuator according to the sum of the difference between the position and the current position of the detector and a second weight; It is characterized in that the first and second weights can be changed.

According to the first embodiment of the present invention, the control means outputs the command force, the command position, and the first and second weights; The actuator is characterized by having a second control means for driving and controlling the actuator based on the detection force and current position of the actuator, the command force from the first control means, the command position, and the first and second weights. According to another embodiment, the detector includes a flexible member that transmits the output of the drive source of the actuator to a driven member, and a detection means that detects displacement between input and output of the flexible member. It is characterized by

Furthermore, according to the second aspect of the present invention, an actuator having a motor and a position detector, an actuator in which a first weight is attached to a difference between a command current value and a current value flowing through the motor, and a command position. control means for driving and controlling the actuator according to the sum of the difference from the current position of the position detector and a second weight; and the second weight can be changed.

According to a second embodiment of the present invention, the control means outputs the command current value, the command position, and the first and second weights; a second control means for driving and controlling the actuator based on the current position of the detector, the current value flowing through the motor, the command current value from the first control means, the command position, and the first and second weights; It is characterized by having the following.

[Effect]

In the present invention, the force applied to the actuator is detected by a force detector (first invention) or the motor current (second invention), and the difference from the command force is obtained to enable force control.
In addition, position control is possible by obtaining the difference between the current position of the position detector and the command position, and the sum of these with predetermined weights is used as the basic control amount, so just by changing the weight, force control is possible. , position control and joint control of force and position are possible.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a configuration diagram of an embodiment of the first invention of the present invention,
In the figure, 1 is a robot, which has a node 1a at its tip and an arm lb that operates a hand la.

1c, ld, , le, and a base 1f, arms lb, Ic, Id, le are rotated by actuators to move the hand 1a, and 21 and 22 are position detectors for each actuator. 3 is a signal processing circuit which constitutes a part of the force and position detector and will be described later.
The one that outputs the detection power f which is the difference between 22 and 4 is the calculation 11
111 (first control means), which monitors the operating state of the robot from the detected position p and detected force f, and also controls the target command position po, target command force fO, and first and second weights a and b. 5 is a control device (second control means) that outputs the drive current l of the drive source (motor) of each actuator, the command position pO1 command force fO1, the first and second weights asb, and the current position p , the detection power f is used to control y in the following equation to zero, and will be described later with reference to FIG.

y = a · Δp + b · Δf ' (1) However, Δp = p o -p +21 Δf = f o - f (31 Figure 2 is a detailed view of the main part of the configuration of the embodiment in Figure 1. ,
Components that are the same as those in FIG.
1 and is constructed in one piece, which will be explained in detail with reference to FIG. 30 is a first counter, and position detector 2
1 for counting position pulses, which is the output of 1, 31 is the second
32 is a difference circuit which takes the difference between the counting position of the first counter 30 and the counting position of the second counter 31, It detects the force f applied to the actuator 2, and these constitute the signal processing circuit 3.

40, 41, 42, and 43 are output buffers of the computer 4, and are for outputting the command force fo, command position po, and weight b-a, respectively. 50 is a difference circuit that calculates the difference Δf between the detection force f from the difference circuit 32 of the signal processing circuit 3 and the command force fO from the output buffer 40 of the computer 4 (
51 is a multiplication circuit;
52 is a difference circuit that multiplies the difference (error) Δf of the difference circuit 50 by the weight b from the output buffer sofa 42 of the computer 4 to generate an output b·Δf. Calculate the difference Δp between the calculated position (current position) p and the command position po from the output sofa 41 of the computer 4 (
53 is a multiplication circuit,
54 is a sum circuit that multiplies the difference (error) Δp of the difference circuit 52 by the weight a from the output sofa 43 of the computer 4 to generate an output a.Δp, and 54 is a sum circuit, and two multiplier circuits 51.
55 is a control circuit that integrates the control amount y and outputs the drive current i of the motor 20. The drive current i is controlled so that the control ff1y becomes zero.

FIG. 3 is a detailed configuration diagram of one embodiment of the actuator in the configuration shown in FIG. 2, FIG. be.

In the figure, 23 is a reducer, which is composed of a well-known gear type reducer, and is provided to reduce the rotational speed of the motor 20 to increase torque (force) and improve the positioning resolution. 20a is a reducer. The shaft of the motor is hollow inside and serves as the rotation axis of the rotor of the motor 20. 21a is a slit disk with an optical slit formed around it, and is provided on the shirt 20a of the motor 20. Something that rotates due to the rotation of the shaft 20a, 21b
, 2IC is an optical sensor, which is provided corresponding to the slit circumference of the slit disk 21a, and transmits the light from the light emitting element 21b to the light receiving element 2IC through the slit of the slit disk 21a.
The position detector 21 detects the position by receiving light, and therefore the position detector 21 is constituted by an optical non-contact rotary encoder. 22a is a slit disk, which has the same configuration as the slit disk 21a, and has the same structure as the shaft 23a of the reducer 23.
22b and 22C are optical sensors having the same configuration as the optical sensors 21b and 21c, and therefore the position detector 22 is also constituted by an optical contact rotary encoder. 24 is a torsion bar, which constitutes a flexible member, connects the shaft 23a of the reducer 23 and the shaft 20a of the motor 20, and is provided in the hollow part of the shaft 20a.
The rotational force of the rotational force is transmitted to the shaft 23a of the reduction gear #R23.

To explain the operation of the structure shown in FIG. 3, the rotational force of the motor 20 is transmitted from the shaft 20a to the shaft 23a of the reducer 23 via the torsion bar 24, and is output from the output shaft 2a. The rotational position of the motor 20 is detected by a position detector 21, and the rotational position of the output shaft 2a is detected by a position detector 22.

Therefore, if the position of the motor 20 is controlled by the output of the position detector 22, accurate positioning can be achieved. On the other hand, force (torque)
is determined by the output difference between the two position detectors 21 and 22 and the rigidity of the 1.-version version 24. Therefore, when some force is applied to the output shaft 2a, the torsion bar 24 is deflected due to its flexibility, and a phase difference occurs in the outputs of the rain detectors 21 and 22. This allows the external force and its magnitude to be detected. can do. That is, rain detectors 21.22
Force detection is possible based on the difference in the counts of counters 30 and 31 in FIG. 2 that count position pulses.

By using such an actuator 2, it is possible to realize a compact force and position detector integrated with a motor, and the rotary encoder is capable of highly accurate position detection, is resistant to noise, and has high reliability. As the flexible member, a spiral spring may be used in addition to the torsion bar.

Returning to FIGS. 1 and 2, the operation will be explained.

Note that although the figure shows one axis, the same applies to the other axes.

First, computer 4 has output buffer 40.41.42.43
Set command force fO1 command position pO1 weights b and a to . As a result, the control device 5 obtains the current position p and the detection force f from the signal processing circuit 3, and uses the configuration shown in FIG.
11 is executed and the drive current i is generated to control the motor 20. Since the control circuit 55 of the control device 5 controls the drive current 1 so that the control amount y becomes zero, if the weight af0,b≠0, the robot 1 is moved to the specified position with the specified force via the motor 2o. The arms 1b to 1e of the controller are controlled.

In this way, the control amount is determined by the position error Δp as shown in equation (1).
Since it takes the form of a sum with weights a and b added to each error Δ', when only position control is performed,
By setting the weights af-0 and b=0, equation (1) becomes y=a°Δp(4), so only position control can be performed.

Similarly, to perform only force control, weight a=Q, b≠0
By setting Equation (1) to y=b·Δf(5), only force control can be performed.

Further, if af0, b≠O, the f+1th equation remains, so combined car position control becomes possible, and the control form can be easily changed by changing the weights a and b.

Similarly, by changing the values of weights a and b, it is possible to provide a more detailed control form. When placing emphasis on force control by setting the weight a to be large and the weight b to be small, fine control can be easily achieved by setting the weight a to be small and the weight b to be large. This is executed by changing the weights a and b as appropriate while the computer 4 grasps the operating state of the robot based on the current position p and detection force f.

That is, as shown in the relationship between position p and force f in FIG.
, b can realize various forms of position-force control.

Next, the second invention of the present invention will be explained.

FIG. 5 is a configuration diagram of an embodiment of the second invention of the present invention,
In the figure, the same components as in FIG. 3
1) and A- which converts the detected current i into a digital value i.
D (analog-to-digital) converter, 5' is a control device, and a drive source for each actuator (
The driving voltage V of motor 6) is expressed as follows by command position po (θo), command force fo (io), first and second weights a, b, current position p (θ), and detection force f (i). This is to control so that y in the equation becomes zero, and will be described later with reference to FIG.

y=a・Δθ+bΔ1 (6) However, Δθ−θ0−θ (7) Δi = t o −f (8) 6 is a current detector, which is for detecting the current value i of the motor 20, This will be described later with reference to FIG.

FIG. 6 is a detailed configuration diagram of the control device 5' in the configuration shown in FIG. 5. In the figure, the same parts as in FIG. Command power (
57 is a difference circuit that takes the difference Δθ between the command position θ0 from the calculation tJl14 and the current position θ. The multiplier circuits 51.53 calculate the weights, a, from the computer 4 and the outputs Δi, Δθ of the difference circuits 56.57 using equations (7) and (8).
It multiplies according to the formula, and the sum circuit 54 is large (6)
The control amount y is output according to the formula. Further, the actuator 2' includes a position detector 22, a motor 20, and a speed reducer 23.

FIG. 7 is an explanatory diagram of the current detector 6 in the configuration shown in FIG.

The electric modem when voltage V is applied to the motor 20 is shown in Figure 7 (
As shown in A), Ro is the external resistance of the motor, and the motor 20 can be expressed by the back electromotive voltage VE% inductance L1 resistance. Therefore, in order to detect the current i flowing through the motor 2°, it is sufficient to detect the voltage applied to the external resistor Ro as shown in FIG. 7(B). That is, it is composed of an input resistor Rs, an operational amplifier 60° and a feed hack resistor Rf.

Here, if Rs >> Ro, the current flowing through the input resistor Rs is negligibly small compared to the current flowing through the external resistor Ro, so the voltage across the external resistor Ro is set by the operational amplifier 60.
By amplifying it appropriately, it is possible to detect the current flowing from the output v1 of the operational amplifier 60 to the external resistor Ro, and by extension, the current flowing to the motor 20.

Returning to FIGS. 5 and 6, the operation will be explained.

Note that, like FIG. 1, only one axis is shown in the figure, but the same applies to the other axes.

First, the computer 4 applies a command current (force) of 10 to the output cover sofa.
, command position θ0. Weights, cents a.

The control device 5' receives the current position θ from the detection signal processing circuit 3'.
and detected current value i, and the (6th
) is executed, the drive voltage V is generated, and the motor 20 is controlled. The control circuit 55 of the control device 5' controls the drive voltage V so that the control amount y becomes zero.

Here, a proportional relationship is established between the current i flowing through the (DC) motor 20 and the output torque T, and if the proportionality constant (torque constant) is kT, then T = kT i (91).

Therefore, by detecting the current i flowing through the motor 20, the output torque T, that is, the force, of the motor can be detected, and the same control as in the first invention is possible.

In this case as well, by changing the weights a and b, the control form can be changed in the same way as in the first invention.

That is, when a≠0, b=o, position control (integral operation) a=Q, b
When ≠0, when force control a≠0 and b≠0, a combination mode (rigidity mode) of both can be realized.

In this second invention, these car position controls can be performed using the same configuration of actuators used in conventional position control systems, making the configuration inexpensive and compact, and also making it possible to easily improve the functionality of conventional robots and nodes. can be converted into

Next, an actual working example will be explained in order to explain the present invention in detail.

FIG. 9, FIG. 10, and FIG. 11 are explanatory diagrams of work examples,
As shown in FIG. 9, this is an example of the work of covering the box 100 with the cover 200.The box 100 has engagement holes 101 and 102, and as shown in FIGS. 200 are inserted into the engaging holes 1011102 of the box 100.

Next, cover 200 is folded down in the direction of the arrow in FIG. 10(A).

Here, as shown in FIG. 11(A), the protrusion 2 of the cover 200
The engagement plate springs 203 and 204 provided in the box 100 are connected to the tapered plate 103 provided in the box 100.
104.

Further, as shown in FIG. 11(B), the cover 200 is locked by the engagement between the leaf spring 203 and the tapered plate 103.

How this work is carried out by the robot 1 shown in the schematic diagram of FIG. 8 will be explained with reference to the flow diagram of FIG. 12.

It is assumed that the positions of the box 100 and the cover 200 are taught in advance.

(2) Move the hand 1a of the robot 1 to the vicinity of the cover 200.

In this case, only position control is required, so force control 1 is not necessary. Therefore, the calculator 4 sets the position command pO to the position of the box, the position weight a-1, the force command f0, and the force weight b.
=o and starts the robot 1.

As a result, the robot's hand 1a moves to the vicinity of the cover 200.

■Next, the calculation tff14 monitors the position of the hand 1a based on the current position p, detects that the hand 1a has moved near the cover 200, and moves the cover 200 to the hand 1a.
In order to understand this, we set the weight a=0.9\b=0.1.

Since it does not require much force for the hand 1a to grip the cover, a force weight of about 0.1 is sufficient. As a result, the hand 1a of the robot 1 comes into contact with the cover 200, and can grip the cover 200 by operating the hand 1a.

■ Next, the calculator 4 sends the position command po for the position of the box 100, lifts the cover 200 with the hand 1a, and then the calculator 4 sends the position weight a-1, the force weight b=Q
The cover 200 is moved to the vicinity of the box 100 only by position control.

■ Furthermore, the computer 4 moves the car positions a-0, 8 and b in order to engage the protrusions 210 and 211 of the cover 200 in the holes 102 and 2 101 of the box 100 in order to perform combined car position control.
=0.2.

This allows the hand 1a to move to the protrusion 210 of the cover 200.
211 into the holes 101 and 102 of the box 100.

(2) Next, the computer 4 closes the cover 200 in the same manner as the box 100. For this, combined car position control is performed, but as mentioned above, since there is an engagement work between the leaf springs 203 and 204 of the cover 200 and the tapered plates 103 and 104 of the box 100, the ratio of force control must be increased (a- , 5, and b=0.5.

As a result, the hand 1a imitates the box 100 and the cover 2
00, and the leaf springs 203 and 204 and the tapered plate 103.
104 is engaged.

(2) Next, open the hand 1a, release the grip on the cover 200, and move the hand 1a slightly upward.

■ Furthermore, in order to return hand 1a to the home position, calculation ta4 sets the command position po of home 3 position, a=], b=Q, moves hand 1a to the home position, and then performs the next step. Prepare for work.

In this way, by simply changing the weight, position control can be performed when carrying parts (positioning), and combined car position control can be performed during engagement, fitting, etc., and the ratio of both car position controls can be controlled. It can be changed according to the work content.

In the first invention described above, an encoder type detector is used as the detector, but other force sensors such as a strain gauge may also be used.

Although the present invention has been described above using one embodiment, the present invention can be modified in various ways according to the gist of the present invention, and these are not excluded from the present invention.

〔Effect of the invention〕

As explained above, according to the first aspect of the present invention, the actuator has a detector for detecting force and position, and a first weight is assigned to the difference between the command force and the detection force of the detector. and a control means for driving and controlling the actuator according to the sum of the difference between the commanded position and the current position of the detector, which is given a second weight, and the difference between the command position and the current position of the detector. Since the first and second weights can be changed at the same time, the control form can be easily changed, and position control, force control, and combined car position control can be performed easily. It is possible to change the ratio in selection and car position combined control by changing the weights, contributing to the sophistication of the robot's work content and greatly contributing to the realization of highly functional robots equivalent to humans. Moreover, it has the effect of being easy to realize.

According to the second aspect of the present invention, an actuator having a motor and a position detector, an actuator in which a first weight is attached to a difference between a command current value and a current value flowing through the motor, and a command position. control means for driving and controlling the actuator according to the sum of the difference from the current position of the position detector and a second weight; and the second weight can be changed, so in addition to the above-mentioned effects of the first invention, such control can be realized without changing the configuration of the conventional robot. It has the advantage that it can be realized easily and at a low cost, and it also has the excellent practical effect that by adding a control device to an existing robot, the functionality of the robot can be increased.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the first invention of the present invention, FIG. 2 is a configuration diagram of main parts of the configuration in FIG. FIG. 4 is a characteristic diagram of the robot according to the present invention, FIG. 5 is a configuration diagram of an embodiment of the second invention of the present invention, FIG. 6 is a configuration diagram of main parts of the configuration shown in FIG. 5, and FIG. Fig. 8, Fig. 9, Fig. 10, and Fig. 11 are explanatory diagrams of the current detector configuration, Fig. 8, Fig. 9, Fig. 10, and Fig. 11 are explanatory drawings on the working side to show the usefulness of the present invention, and Fig. 12 is Fig. 8 to Fig. 11. FIG. In the figure, l-robot, la-hand, 1b to 1e-arm, 2-actuator, 20-motor, 6-21.22-position detector, 4-computer, 5.5'-
Control device, 6-current detector. Patent Applicant Fujitsu Ltd. Representative Patent Attorney Akira Yamatani 7 Figure 1 Figure 4 f Figure 5 Figure 6 Figure 7 (A) (B) Figure q Procedural amendment (voluntary) Figure 12 Contents of the amendment January 16, 1985 2 Title of the invention Robot control method 3 Relationship to the person making the amendment Patent applicant address 1015 Kamiodanaka, Nakahara-ku, Yozaki-shi, Kanagawa Name (522) Fujitsu Ltd. Representative: Takuma Yamamoto 4, Agent address: 1-19-8-6 Kanda-Awajicho, Chiyoda-ku, Tokyo
, Subject of amendment Column 7 of Detailed explanation of the invention in the specification, Contents of amendment As shown in Attachment 1, "Position detector" in Lines 5, 7, and 9 of page 10 of the specification is replaced with "Position detector" I am corrected by saying ``vessel''. 2. Correct "Equation (2)" on the last line of the same page to "Equation (3)". 3. Correct "calculation position" in the fourth line of page 11 to "counting position". 4. Correct "No. (3)" in the 6th line of the same page to "No. (2)". 5. Correct "contacted" in the last line of page 12 to "non-contacted". 6. Correct "Large Equation (6)" in the second line of page 18 to "Equation (6)". 7. Correct "modem" in line 8 of the same page to "model". that's all

Claims (1)

[Claims] control means for driving and controlling the actuator according to the sum of the difference from the current position of the device and a second weight; (2) a first control means for outputting the command force, the command position, and the first and second weights; and a second control means for driving and controlling the actuator according to the detection force and current position of the detector, the command force and command position from the first control means, and the first and second weights. (3) The detector includes a flexible member that transmits the output of the drive source of the actuator to a driven member, and an input member of the flexible member. Claim No. 11 or (2), characterized in that:
Control method of robot described in section. (4) An actuator that has a motor and a position detector, and a first
control means for driving and controlling the actuator according to the sum of a weighted value and a second weighted difference between the command position and the current position of the position detector; 1. A control method for a robot, characterized in that the first and second weights can be changed. (5) a first control means for the control means to output the command current value, the command position, and the first and second weights;
a second control for driving and controlling the actuator based on the current position of the position detector, the current value flowing through the motor, the command current value from the first control means, the command position, and the first and second weights; 4. A robot control system according to claim 4, further comprising: means.