JPH07164363A - Control device of hand mechanism - Google Patents

Abstract

PURPOSE:To provide the control device of a hand mechanism which can decide whether the grasping is succeeded or failed without installing a sensor and the like to a finger. CONSTITUTION:The first object position setting device 19 to set the first object position to grasp a work by a finger, grasping force control devices 14 and 15 to control the driving source of the finger so as to move the finger to the first object position in the condition device maintaining a specific grasping force, and a speed detecting device 13 to detect the moving speed of the finger depending on the output of a position detecting device 102, are provided. Furthermore, a grasping detecting device 18 to decide whether the finger grasps a work or not by comparing the present position and the first object position of the finger, after it is decided that the moving speed of the finger maintained at a specific grasping force is made zero, is also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hand mechanism controller for causing fingers of a robot hand mechanism to perform a gripping operation.

[0002]

2. Description of the Related Art Conventionally, in a robot hand mechanism, as shown in FIG. 11, when a gripping operation is completed or failed, a load sensor is attached to a work contact surface of a finger, or a strain gauge or a proximity sensor is attached to the finger. Then, the output is used to make the determination.

[0003]

However, in the above-mentioned conventional example, since the load sensor, the strain gauge, the proximity sensor, etc. are attached to the finger, it is costly, requires a lot of space, and requires an output signal amplifier. ,
As a result, the device itself becomes large-scaled, complicated, and impractical. There is also a problem that there is no highly reliable strain gauge itself.

In addition to the above problems, there are also the following problems. That is, in the conventional robot hand mechanism, when the gripping force of the finger is controlled, it is necessary to externally set the target gripping force and in which direction the gripping force should be generated. More specifically, for example, as shown in FIG. 12, it is possible to determine the gripping force control or the positioning control determination data, the target position data and the target speed data that are the positioning control data, and the gripping force control data. It was necessary to input a total of five pieces of data of a certain target gripping force and data of the direction in which the gripping force is generated to the control device from the outside. Therefore, there is a problem in that a space for storing these large amounts of data is required in the control device, and the storage area in the control device is not used efficiently. Further, when inputting the data of the direction in which the gripping force is generated, there is a problem that it is confusing to determine which is the + direction and which is the − direction.

Therefore, the present invention has been made in view of the above-mentioned problems, and a first object of the present invention is to provide a hand mechanism which can judge the success or failure of gripping without attaching a sensor or the like to a finger. It is to provide a control device. A second object of the present invention is to provide a hand mechanism control device capable of reducing the number of data input from the outside.

[0006]

In order to solve the above-mentioned problems and achieve the object, a controller for a hand mechanism according to the present invention provides a drive source for moving a finger and a drive force of the drive source. A controller for a hand mechanism for controlling a robot hand mechanism, comprising a transmission means for transmitting to the finger and a position detection means for detecting the current position of the finger, the finger gripping a workpiece. A first target position setting means for setting a first target position for moving the finger, and the finger is moved toward the first target position while maintaining the gripping force of the finger at a predetermined gripping force. Therefore, the gripping force control means for controlling the drive source, the speed detection means for detecting the moving speed of the finger based on the output of the position detection means, and the predetermined gripping means by the speed detection means. After it is detected that the moving speed of the finger maintained at the force becomes zero, the current position of the finger is compared with the first target position to determine whether the finger grips the workpiece. And a grip determination means for determining.

Further, in the controller for the hand mechanism according to the present invention, the first target position is a position inside the contour of the workpiece in the moving direction of the finger. Further, the control device for a hand mechanism according to the present invention is characterized by further comprising gripping force setting means for setting gripping force data for generating the predetermined gripping force on the fingers.

In the control device for a hand mechanism according to the present invention, the gripping force control means compares the current position of the finger with the first target position to move the finger in either direction. It is characterized by including a direction determining means for determining whether or not. Further, in the controller for the hand mechanism according to the present invention, there is provided positioning control means for controlling the driving means so as to position the finger at a second target position located outside the contour of the work, A position error detection circuit that detects a position error between the current position of the finger and the second target position based on the output of the detection unit, and a current movement speed of the finger and a predetermined value based on the output of the speed detection unit. And a speed error detection circuit for detecting an error with respect to the target moving speed.

In the hand mechanism control device according to the present invention, the positioning control means further comprises second setting means for setting the second target position and the predetermined target moving speed. I am trying. Further, in the control device for the hand mechanism according to the present invention, a state in which the drive source is controlled by the gripping force control means,
It is characterized by further comprising switching means for switching between a state in which the drive source is controlled by the positioning control means.

Further, in the controller of the hand mechanism according to the present invention, the position detecting means is an encoder connected to the drive source. Also,
In the controller for the hand mechanism according to the present invention, the drive source is a servo motor. Further, in the control device of the hand mechanism according to the present invention,
When the robot hand is moved by the robot,
It is characterized in that the current position of the finger and the first target position are compared every predetermined time.

[0011]

As described above, since the control device for the hand mechanism according to the present invention is configured, when the finger moves while maintaining a constant gripping force, the finger stop position and the first target position are set. By comparison, when the stop position passes the first target position, it is determined that the gripping has failed, and when the stop position is before the first target position, the finger contacts the work. By assuming that the finger has stopped and judging that the gripping has succeeded, it is possible to judge the success or failure of the gripping without providing a special sensor or the like on the finger.

Further, by providing the direction determining means for comparing the current position of the finger and the target position to determine the direction in which the finger should move, it is not necessary to input the moving direction of the finger from the outside, and the control device can be provided. The amount of input data can be reduced. Also, when the hand mechanism is moved by the robot, the current position of the finger and the first position
It is possible to monitor that the hand has not dropped the work by repeating the comparison with the target position of No. 1 every predetermined time.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below. <System Configuration> FIG. 1 shows a development example of a robot hand and a control device therefor, which is a target of one embodiment.

In the figure, 11 is a robot hand mechanism, 12 is a finger which is included in the robot hand mechanism 11 and actually grips a workpiece, and 13 is a controller which controls the robot hand mechanism 11. Reference numeral 14 is an assembly work robot including a robot hand mechanism, and 15 is a controller for controlling the assembly work robot 14. Reference numeral 16 is connected to a controller 13 for controlling the robot hand mechanism 11, and data such as a target position, a target speed and a gripping operation for operating the robot hand mechanism 11 is registered in a teaching data table of the controller 13 of the robot hand mechanism. Is a teaching device capable of operating or directly operating the robot hand mechanism 11, and 17 and 18 are interfaces of respective controllers.

FIG. 2 is a diagram showing a robot hand mechanism. 2, 101 is a servo motor, 102 is a pulse encoder for position detection connected to the servo motor 101, 103 is a timing pulley attached to the rotation output shaft of the servo motor, 104 is a timing belt,
Reference numeral 105 is a timing pulley located on the opposite side of the pulley 103, and 106 is a ball screw with left and right screws. 107 and 108 are linear guides, and 109,1
10 is a finger part which is a movable part to which a nut (not shown) for the ball screw 106 is attached, 11
Reference numerals 1 and 112 denote finger stoppers attached to the finger portion and the fixed frame 113 separately. Reference numeral 115 is an origin sensor for positioning the origin of the finger portion. Reference numeral 114 is a mounting flange for mounting the entire robot hand mechanism section to the tip of the industrial robot.

In the operation of the robot hand mechanism, the rotation output of the servo motor 101 is transmitted to the timing pulley 103, the timing belt 104 and the timing pulley 105, and the ball screw 106 is rotated. As a result, the finger portions 109 and 110 can move linearly in the direction of moving away from each other and the direction of moving closer to each other, and the work can be gripped by these two fingers. In addition, the servo motor 101
The positions of the finger portions 109 and 110 can be detected by the pulse encoder 102 attached to the. Further, the origin of the positions of the finger portions 109 and 110 can be set with reference to the origin sensor 115. When the finger portions 109 and 110 move in the separating direction, the stopper 112 of the finger 110 and the stopper 111 of the frame 113 come into contact with each other before the finger 109 comes into contact with the frame 113.

<Overall Operation> Next, the robot hand mechanism 1
1, the overall operation of the controller 13 of the robot hand mechanism, the assembling work robot 14, and the assembling work robot controller 15 will be described. First, the assembling robot controller 15 uses the assembling robot 1 to hold a target work by the robot hand mechanism 11.
4 is operated. Next, the assembly work controller 15
Is actually the finger 1 from the input / output interface 17.
2 outputs an operation signal pattern for gripping a target work.

This operation signal pattern is shown in FIG. In this embodiment, as shown in FIG. 4, eight patterns are prepared. The structure of each pattern is, as shown in FIG.
"Start bit" that consists of 4 bits in total and indicates the start of the operation (indicated by a symbol with a circle in FIG. 4)
And the operation type bit of 3 bits. In this embodiment, the operation is not started when the start bit is "0" regardless of the kind of the operation type bit. When the start bit is "1", the operation set by the operation type bit, for example, the operation indicated by n = 0, 1, 2, ... 7 in FIG. 7 can be executed.

FIG. 4 illustrates eight kinds of operation commands for the fingers. The 3-bit operation type bit determines the value of the operation pattern n. Eight operation patterns from n = 0 to n = 7 are set. For example, a pattern of n = 0 indicates a "home search" operation, and an operation having a pattern of n = 1 is to move to a position X ₁ at a speed V ₁ .

The operation having a pattern of n = 2 is for gripping the work, and the finger is operated from the current position of the finger (standby position) toward the target position X ₂ to move the work. It is to grasp.
Then, using the target position X ₂ as the grip reference position, it is judged whether gripping is completed or failed by comparing with the current position. The data after n = 3 is the same as when n = 1 and 2.

The number of bits may be further increased to increase the number of point data. The table in FIG.
Stored in M. Robot hand mechanism controller 13
Is a signal corresponding to the data such as the target position, the target speed, and the gripping operation which are recorded in advance in the teaching data table in the robot hand mechanism controller 13 by the teaching device 16 by inputting the signal pattern from the input / output interface 18. The same pattern is selected and the finger 12 is caused to start the operation indicated by the data, and the positioning operation and the work gripping operation are performed.

Next, when the fingers 12 actually perform the target positioning operation and workpiece holding operation, the robot hand mechanism controller 13 causes the input / output interface 18 to operate.
The assembly work controller 15 outputs an operation completion signal to the assembly work robot controller 15 and fetches the completion signal from the input / output interface 17.
Starts the next operation of the assembly work robot 14.

<Teaching Device> FIG. 5 shows an example of an operation panel of the teaching device 16 for the robot hand mechanism. Reference numeral 61 is a current value and teaching data display section of the finger 12, 62 is a current value taken from the robot hand mechanism controller 13 when the operation of the finger 12 is completed, and Point ¹ , 2, ... 2 ^{n-1 at} 63 is displayed. 1 is a point name on which the finger 12 should operate, and corresponds to the above-mentioned bit patterns n = 1, 2, 3, ... 7 (in the case of 4 bits).

Reference numeral 64 represents a portion of data which can be taught at the time of teaching work. Reference numeral 65 is a ten-key for directly inputting teaching data, 66 is a key for directly selecting a position component, a velocity component, and a gripping component when performing a teaching work, and 67 is a 6
Reference numeral 68 is a key used for moving 4 up, down, left and right, and 68 is a registration key for confirming each taught data.

FIG. 6 shows an example of the screen display of the teaching device.
(A) shows the case of the positioning operation command, and (b) shows the case of the gripping operation command. The current data is displayed on the first line, and point data is displayed on the second and subsequent lines (Point1,
Point 2, ...). The components of the data are the target position, the target speed, and the grip.

In the case of (a), the target position +0010.00
Means that the positioning operation is performed at the target speed of 100%. In the case of (b), the target position is +001 from the current position.
This means that the gripping motion difference is made toward the direction of 5.00. "NO" and "YES" in the gripping item represent data for determining whether to perform the gripping operation. In this case, "NO" is displayed and the positioning operation is
The gripping operation is performed by "ES". The target position data when performing the gripping operation serves as a reference value for determining the direction in which the fingers should move to perform the gripping operation, and whether the gripping operation is completed or the gripping operation fails. It also has two roles of a reference value for determining.

The item of the target speed in the gripping operation is not set. This is because it is meaningless to specify the speed in the gripping operation because the gripping force is controlled so as to have a predetermined value. As another method of setting the gripping data, the gripping force data can be directly set. This is because gripping force data is set to "0" in the case of positioning control and gripping force data (for example, 3 k) that can generate a target predetermined gripping force for fingers other than "0" in gripping force control.
If a gripping force of gf is desired, a method of setting numerical data (absolute value data) corresponding thereto can be considered.

In addition, in the above example, each data is handled as point data, but it is also possible to describe this in operation program format. A personal computer or the like may be used as the teaching device. In that case, do not care about the display format. FIG. 7 is a control block diagram relating to a gripping force control method for the hand mechanical mechanism. FIG. 7 is composed of two loops, a positioning control loop (indicated by a solid line frame in the figure) and a gripping force control loop (indicated by a broken line frame in the diagram). The positioning control loop is a loop for positioning the finger at the "preparation position", and the gripping force control loop is a loop for controlling the gripping force generated by the finger after the finger is placed at the preparation position.

Positioning Control First, the positioning control loop will be described. A command position register 1 in the figure is a register that stores a target command position. The target command position from the command value register 1 is output to the adder 2. The adder 2 obtains the position deviation between the target command position and the current position of the finger and outputs it to the position loop gain multiplier 3. The position loop gain multiplier 3 multiplies the position deviation by a predetermined control gain to calculate a target speed, and outputs the target speed to the adder 4. The adder 4 obtains a speed deviation between the input target moving speed and the current moving speed of the finger, and outputs it to the speed loop gain multiplier 5. The speed loop gain multiplier 5 multiplies the input speed deviation by a predetermined control gain and outputs the target command current to the adder 7. The adder 7 obtains a current deviation between the input target command current and the current command current currently output to the servo motor 101, and calculates this current deviation.
Output to. The torque amplifier 8 amplifies the input current deviation and outputs it as a command current to the servo motor 101. The servo motor 101 is driven by the input command current and generates torque to open and close the fingers 109 and 110 of the hand mechanical mechanism to perform positioning. The encoder 102 outputs a signal corresponding to the rotation of the servo motor 101 to the current position counter 204 in order to detect the current position of the finger unit, and the current position counter 20
Reference numeral 4 calculates the current position from the signal from the encoder 102 and sets it as the current position. In addition, the current position counter 204
Is output as the current speed through the differentiator 13. These are the conventional positioning control loops.

Gripping Force Control Next, the operation for the finger part to actually grip the target work is performed as follows. By the position control of the fingers, a standby position for gripping the work (this standby position is a position with some margin with respect to the size of the target work, that is, the position between the target work and the fingers when positioned there). After the positioning is made such that there is a certain interval between them, the loop switch 6 is switched from the positioning control loop side (position b in the figure) to the gripping force control loop (position a).

Then, the command gripping force 14 is set and output to the gripping force / torque calculating unit 15. At this time, the current position and the commanded position that is the target position are input to the direction determination circuit 20, and it is determined in which direction the finger should be driven. Then, the directionality is output to the gripping force / torque calculating unit 15.

The gripping force / torque calculation unit 15 has a conversion function for converting the commanded gripping force into a torque (current) value. When the commanded gripping force is input, the torque (current) value required for the command gripping force is input from the direction determination circuit 20. Is calculated in consideration of the output result of and output as a command torque (current) value. Generally, the servo motor generates torque in proportion to the command current value,
Naturally, the torque and the force generated thereby are in a proportional relationship, so the force generated with respect to the command current value is always in a proportional relationship. Therefore, a simple conversion function is prepared in the gripping force / torque calculating unit 15.

When the command gripping force is input to the gripping force / torque calculating section 15, it is converted into a torque (current) value by the conversion function and is output to the adder 7 through the loop changeover switch 6 as a command value. Then, the constant current value control is performed by the current control loop (loop returning from the torque amplifier 8 to the calculator 7) to generate a constant torque in the servo motor 101 to operate the hand mechanical mechanism, and the finger 10 is operated.
9, 110 is brought into contact with the object.

When the finger portion of the hand mechanical mechanism starts to move in the direction of gripping the target work according to the command gripping force. This time, the speed monitor 16 monitors the current speed output from the differentiator 13. At the time when the current speed becomes speed = 0 (speed = 0 means that the finger is in contact with the work or has moved to the movement limit position or the stopper).
Whether or not the gripping operation is completed by the gripping confirmation device 18 (whether the finger has reached a target gripping force with respect to the target work and gripped) or has failed has been input as a gripping reference position (externally input as a target position). ) 19 for comparison.

In this embodiment, the gripping force instruction is used. However, since the constant current value control is used, a method of directly inputting a command current value for the target gripping force to the current control loop from the beginning, or There is a method of giving instructions in the form of torque. FIG. 8 shows a hardware configuration diagram of the control device. 201 is a central processing unit (CPU) that realizes control
202 is bus-connected to the CPU 201 and is a non-volatile memory (RO) including a series of control processing algorithm programs and a man-machine interface program.
M), and 203 is a memory (RAM) backed up by power supply capable of storing teaching data. Also, 204
Is a pulse encoder 1 connected to the servo motor 101
02 is a current value counter that can be connected to 02 to count the current position of the servo motor. Reference numeral 208 denotes a D / A converter connected to the servo motor through the torque amplifier 209, and can output an analog current value to the torque amplifier 209 according to an instruction from the CPU 201.
Reference numeral 206 denotes information of the origin sensor 115 and external I / O 11
The information such as the operation signal pattern of the hand mechanical mechanism input through 6 and the operation end signal of the hand mechanical mechanism are sent to the CP.
This is an I / O interface for importing into U201. Further, reference numeral 211 is a communication interface connecting the external teaching device 212 and the CPU. 202, 203,
All of 204, 206, 208, 211 are connected to the CPU 201 by a bus 213.

FIG. 9 is a flow chart for explaining the operation of the fingers. When the movement point is designated for the finger (S-1), it is determined whether the point is the origin-finding operation or another (S-2).
If a home search operation request is made, start home search (S-3),
When it is finished, it outputs the origin return completion and finishes (S-4).
If a request other than the home search operation is requested, it is determined whether it is a gripping operation or a positioning operation (S-
5).

If it is determined to be the positioning operation, the control loop is switched to the position control loop if the previous operation is the gripping operation. Then, the target position and the target speed are set, the normal positioning operation is started, and when the operation is completed, the movement completion is output and the operation is ended (S-5 to 9). When it is determined to be the gripping operation, the current position of the finger is compared with the target position of the point data (hereinafter referred to as Pob) (S-1).
0).

When the current position is smaller, the target gripping force is given a positive or negative directivity so that the work can be gripped from the outside and the fingers can move in the closing direction. In this embodiment, the value is positive (S-11). next,
The control loop is switched from the position control loop to the grip force control loop (S-12). Then, the fingers start to move in the closing direction.

The current state is continuously maintained until the movement amount at Δt time becomes "0" (S-13). When the amount of movement in Δt time becomes “0”, the current position and Pob are compared (S-14). If the current position is smaller than or equal to Pob, the gripping is considered to be completed and a completion output is made (S-15). If the current position is larger than Pob, a gripping error is output because the workpiece cannot be gripped (S-16).

After the grip completion output or the grip error output, the finger operation is terminated. After the completion of gripping and the completion output, the current position and Pob are compared at regular intervals until the next finger operation command is issued. It is also possible to monitor the removal of the work such as movement.
Alternatively, the same result can be obtained by executing the same operation command again during conveyance.

At S-10, the current position is Pob.
If it is larger than the above, the target gripping force is given a positive or negative directivity so that the work can be operated in the direction of opening the finger as if gripping the work from the inside (for example, a hollow cylindrical work). In this embodiment, it is negative (S-18). Next, the control loop is switched from the position control loop to the gripping force control loop (S-19). Then, the fingers start to move in the opening direction.

The current state is continuously maintained until the movement amount at Δt time becomes "0" (S-20). Then, when the movement amount in the Δt time becomes “0”, the current position and Pob are compared (S-21). If the current position is greater than or equal to Pob, the gripping is considered to be completed and a completion output is output (S-15). If the current position is smaller than Pob, a gripping error is output assuming that the workpiece cannot be gripped (S-16).

After the grip completion output or the grip error output, the finger operation is terminated. After the completion of gripping and the completion output, the current position and Pob are compared at regular intervals until the next finger operation command is issued. It is also possible to monitor the removal of the work such as movement.
Alternatively, the same result can be obtained by executing the same operation command again during conveyance.

The concept of the position used in this embodiment is that the direction in which the fingers are closed is positive and the direction in which the fingers are open is negative. In S-5, the gripping operation or the positioning operation can be easily determined based on whether or not a value is set in the target gripping force of the point data of the designated point. For example, in the case of positioning, "0"("NO","0", etc. on the screen of the teaching device), and in the case of gripping force operation, data other than "0" is "1", "2" (of the teaching device. "+", "-" Or "CLOS on the screen
E "," OPEN "," YES ", etc.), in this case, the target gripping force is the same for each point data,
The parameters are set in advance (in the form of target gripping force, target torque, target current, etc.).

When it is desired to change it for each point data, the target gripping force is directly set for each point data (the format is target gripping force, target torque or target current, etc.). The above explanation is an example, and in short,
Whether it is the positioning operation or the gripping operation may be determined from the target gripping force data of the point data.

Depending on S-10 to 11 or 18, the present position (waiting position of the finger before gripping the work) and Po.
By comparing with b, the direction in which the finger must be operated to grip the work is determined. In the state shown in FIG. 10A, the finger for gripping the work is positioned at the standby position (position indicated by 2a). This position is 10
The position is mm (the position indicated by 1a is the origin position of the finger).

Next, assuming that 17 mm of data (position 4a) is set in Pob as point data for gripping this work, the finger must move to the position in the + direction from the current position. . Therefore, when the control loop for positioning is switched to the gripping force control loop, the target gripping force, the target torque, or the target current has positive or negative directivity so that the finger can move in the + direction. Here, it is assumed that the motor can move the finger in the + direction by setting the positive value.

On the contrary, when the hollow cylindrical work is gripped as shown in (b), the finger is positioned at the position 2b as the standby position. Next, assuming that data of 5 mm (position of 4b) is set in Pob as point data for gripping this work, the finger must move to a position in the-direction from the current position. Therefore, when the positioning control loop is switched to the gripping force control loop, the target gripping force, the target torque, or the target current has positive or negative directivity so that the finger can move in the-direction. Here, it is assumed that the motor can move the finger in the negative direction by setting the negative value.

When the target gripping force including the direction in which the finger should move is set, the control loop is switched to start the gripping operation. In S-13 and 20, the counter is still operating even after the control loop is switched, so while monitoring the amount of change in Δt time, "0" is displayed.
The current status is maintained until. If the change amount of the counter becomes “0” without moving the finger during Δt time,
The current position and Pob (4a, 4b) are compared (S-14).
Or 21). If the finger was moving in the + direction,
If the current position (3a) is smaller than Pob, it is assumed that the finger gripping work has been completed. Current position is Po
If it is larger than b, it is determined that the fingers cannot grip the work and have reached the movement limit position or the stopper, and the gripping operation has failed.

If the finger was operating in the-direction,
If the current position (3b) is larger than Pob, it is assumed that the finger has completed the work gripping operation. Current position is Po
If it is smaller than b, it is determined that the fingers cannot grip the work and have reached the movement limit position or the stopper, and the gripping operation has failed. In the case of setting the gripping operation, in the case of FIG. 10A, the set value of Pob is a position inside (larger) of the work than the position of the finger when gripping the work, and the movement limit position and the position of the stopper. The position is outside (smaller) than. In the case of FIG. 10B, on the contrary, the position is outside (smaller) of the work than the position of the finger when gripping the work, and inside (larger) than the movement limit position and the position of the stopper. Here, it is stated that the position is large or small, but this changes depending on the polarity of the motor or the transmission system of the mechanism which is determined in advance.

That is, the Pob set value in the case of the gripping operation is determined at the same time when the direction in which the finger should move is determined.
It also has the meaning of two reference values for determining the completion of the gripping operation or the failure of the gripping operation. The present invention may be applied to a system including a plurality of devices or an apparatus including one device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

Further, the present invention can be applied to the modified or modified embodiments described above without departing from the spirit of the invention.

[0053]

As described above, according to the controller for a hand mechanism of the present invention, when the finger moves while maintaining a constant gripping force, the stop position of the finger is compared with the first target position. Then, if the stop position passes the first target position, it is determined that the gripping has failed, and the stop position is the first target position.
When the finger is in front of the target position, it is judged that the finger has come into contact with the workpiece and stopped, and it is determined that the finger has been successfully gripped. Therefore, the success or failure of the grip is determined without providing a special sensor or the like on the finger. be able to.

Further, by providing the direction determining means for comparing the current position of the finger with the target position to determine the direction in which the finger should move, it is not necessary to input the moving direction of the finger from the outside, and the control device can be provided. The amount of input data can be reduced. Also, when the hand mechanism is moved by the robot, the current position of the finger and the first position
It is possible to monitor that the hand has not dropped the work by repeating the comparison with the target position of No. 1 every predetermined time.

[Brief description of drawings]

FIG. 1 is a diagram showing a development example of a robot hand and a control device therefor according to an embodiment.

FIG. 2 is a diagram showing a robot hand mechanism.

FIG. 3 is a diagram showing an operation signal pattern for gripping a work.

FIG. 4 is a diagram showing an example of operation commands to fingers.

FIG. 5 is a diagram showing an example of an operation panel of a teaching device for a robot hand mechanism.

FIG. 6 is a diagram showing an example of a screen display of a teaching device.

FIG. 7 is a control block diagram relating to a gripping force control method for a hand mechanical mechanism.

FIG. 8 is a hardware configuration diagram of a control device.

FIG. 9 is a flowchart explaining the operation of the finger.

FIG. 10 is a diagram showing the relationship between the shape of the work and the standby position of the fingers.

FIG. 11 is a diagram showing a conventional example.

FIG. 12 is a diagram showing a conventional example.

[Explanation of symbols]

 11 Robot Hand Mechanism 12 Fingers 13 Controller 14 Assembly Robot 15 Controller 16 Teaching Device 17, 18 Interface

Claims (10)

[Claims] 1. A drive source for moving a finger,
A hand mechanism control device for controlling a robot hand mechanism, comprising: a transmission means for transmitting a driving force of the drive source to the finger; and a position detection means for detecting a current position of the finger. A first target position setting means for setting a first target position for the finger to grip a work; and a first target position setting means for maintaining a gripping force of the finger at a predetermined gripping force. Gripping force control means for controlling the drive source to move the fingers toward the direction, speed detection means for detecting the moving speed of the fingers based on the output of the position detection means, and the speed detection means After it is detected that the moving speed of the finger maintained at a predetermined gripping force becomes zero, the current position of the finger is compared with the first target position, and the finger is moved. And a gripping determination unit that determines whether or not the workpiece has gripped the work. 2. The control device for a hand mechanism according to claim 1, wherein the first target position is a position inside the contour of the workpiece in the moving direction of the finger. 3. The control device for a hand mechanism according to claim 1, further comprising a gripping force setting means for setting gripping force data for generating the predetermined gripping force on the finger. 4. The gripping force control means includes direction determination means for comparing the current position of the finger with the first target position to determine in which direction the finger should be moved. The control device of the hand mechanism according to claim 1. 5. A second member located outside the contour of the workpiece.
Positioning control means for controlling the drive means so as to position the finger at the target position of, the position error between the current position of the finger and the second target position based on the output of the position detection means. Positioning control means further includes a position error detection circuit that detects the position error and a speed error detection circuit that detects an error between the current movement speed of the finger and a predetermined target movement speed based on the output of the speed detection means. The control device for the hand mechanism according to claim 1, wherein: 6. The hand mechanism according to claim 5, wherein the positioning control means further includes second setting means for setting the second target position and the predetermined target moving speed. Control device. 7. A switching means for switching between a state in which the drive source is controlled by the gripping force control means and a state in which the drive source is controlled by the positioning control means. The control device for the hand mechanism according to claim 5. 8. The control device for a hand mechanism according to claim 1, wherein the position detecting means is an encoder connected to the drive source. 9. The controller of the hand mechanism according to claim 1, wherein the drive source is a servo motor. 10. The hand according to claim 1, wherein, when the robot hand is moved by the robot, a comparison between the current position of the finger and the first target position is executed every predetermined time. Mechanism control device.