JP2016203266A - Robot hand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly execute a gripping operation of an object.SOLUTION: When the execution of acquisition of a teaching position is required (YES in S100), a control section of a robot hand executes control processing including a step for executing teaching control (S102), a step for acquiring a teaching position (S104), a step for executing attitude control (S106), a step for executing closing control (S108), and a step for updating the teaching position (S112) when the occurrence of warpage is determined (YES in S110).SELECTED DRAWING: Figure 8

Description

  The present invention relates to control of a plurality of fingers of a robot hand.

  In a robot arm having an arm in which a plurality of arm constituent units are connected via joints and a robot hand having a finger in which a plurality of finger constituent units are connected via joints, position control of the arms and fingers For example, an operation of gripping the object is performed. As such a conventional robot apparatus, for example, JP 2012-236237 A (Patent Document 1) discloses a gripping operation of a robot hand using a contact detection finger.

JP 2012-236237 A

  When gripping an object using a robot hand having a plurality of fingers, if the number of joints of the robot hand is large, when the object is gripped using the fingers, There may be deviation. If the gripping position shifts, the posture in which the robot hand grips the target object will not be constant, so there may be cases where the moving operation to move the target object to a specific position or the assembly operation to combine the target object with other parts cannot be performed properly is there. If the gripping position of the object is shifted even if the contact detection finger is used as in the robot hand disclosed in Patent Document 1, the above-described movement operation and assembly operation may not be appropriately performed.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a robot hand that appropriately executes a gripping operation of an object.

  A robot hand according to an aspect of the present invention includes a first finger portion, a second finger portion, and a base portion to which the first finger portion and the second finger portion are connected. The first finger portion includes a first fingertip portion and a first fingertip portion. The first finger part and the second finger part are operated by a plurality of motors. The robot hand detects a rotation position of each of a plurality of motors, and controls the operations of the first finger section and the second finger section based on the rotation positions of the plurality of motors acquired by the detection section. And a control device. The control device performs teaching control for gripping an object using the first finger portion and the second finger portion and acquiring each rotational position of the plurality of motors in the state where the object is gripped as a teaching position. To do. The control device controls a motor other than the first motor such that each rotational position of a motor other than the first motor that moves the first fingertip portion relative to the first fingertip portion among the plurality of motors is a teaching position. At the same time, posture control is performed to control the first motor so that the rotational position of the first motor is at a position where the first fingertip portion is separated from the object. After executing the posture control, the control device executes a closing control for controlling the first motor so that the first fingertip portion approaches the second finger portion. During the execution of the closing control, the control device separates the first finger base portion from the second finger portion by the rotational position of the second motor that moves the first finger base portion of the plurality of motors relative to the base portion. When the change is made to rotate in the direction, the teaching position of the first motor is updated based on the rotation position of the first motor at the time when the change occurs.

  Preferably, when gripping an object after the teaching position of the first motor is updated, the control device performs posture control based on the teaching position, and the rotational position of the first motor is set to the updated teaching position. Close control is executed until.

  More preferably, when the control device changes the rotation position of the second motor so as to rotate in the direction separating the first finger base from the second finger during execution of the closing control, If it is determined that the gripping is completed and the rotational position of the second motor does not change so as to rotate in the direction separating the first finger base from the second finger, the object is not in a grippable position. judge.

  According to the present invention, when the closing control is executed after the posture control, the rotation position of the second motor changes to rotate in the direction separating the first finger base from the second finger. In addition, the teaching position of the rotational position of the first motor can be acquired. Therefore, when performing an operation of gripping an object, each rotational position of motors other than the first motor becomes a teaching position by posture control, so that the first fingertip portion contacts the object during execution of the closing control. The movement of the object can also be suppressed. Therefore, the shift of the grip position can be suppressed. Further, by moving the rotational position of the first motor until the updated teaching position is reached, a constant gripping force can be generated on the object by the first finger portion and the second finger portion. For this reason, the posture of gripping the object can be made constant every time by suppressing the shift of the gripping position and generating a constant gripping force. Therefore, it is possible to provide a robot hand that appropriately executes a gripping operation of an object.

It is a figure which shows the structure of a robot hand typically. It is a block diagram which shows the structure of the control system of a robot hand. It is a figure for demonstrating teaching control. It is a figure for demonstrating attitude | position control. It is a figure for demonstrating closing control. It is a figure for demonstrating curvature determination. It is a figure for demonstrating idling determination. In this Embodiment, it is a flowchart which shows the control processing performed by a control part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a diagram schematically showing a configuration of a robot hand 1 according to the present embodiment. The configuration of the robot hand 1 shown in FIG. 1 is an example, and is not limited to the configuration shown in FIG.

  The robot hand 1 includes a hand unit 10 for gripping an object and a control unit 100 that controls the movement of the hand unit 10.

  The control unit 100 includes a CPU (Central Processing Unit) (not shown) and a storage unit 102 (see FIG. 2) such as a memory described later. The control unit 100 executes a predetermined calculation process based on the detection result from each encoder and the information stored in the storage unit 102, and controls the operation of each motor via the drive unit 70 based on the calculation result.

  The hand part 10 includes a first finger part 20a, a second finger part 20b, and a base part 30 on which the first finger part 20a and the second finger part 20b are supported at a predetermined distance. The 1st finger part 20a and the 2nd finger part 20b are connected to base part 30 so that rotation is possible. In the present embodiment, an example in which the number of finger parts of the robot hand 1 is two will be described. However, the number of finger parts is not limited to two, and at least two finger parts arranged opposite to each other are not limited. There may be a finger part, for example, three or more.

  The first finger portion 20a includes a first fingertip portion 21a, a first fingertip joint portion 22a, a first fingertip portion 23a, and a first fingertip joint portion 24a. One end of the first fingertip portion 23a is connected to the base portion 30 via the first fingertip joint portion 24a, and the other end of the first fingertip portion 23a is connected to the first fingertip portion 21a via the first fingertip joint portion 22a. Connected to. In the present embodiment, the number of finger joints is two, but the number of finger joints is not limited to two, and may be three or more, for example.

  The first fingertip joint portion 22a is provided between the first fingertip portion 21a and the first fingertip portion 23a, and is capable of rotating the first fingertip portion 21a in the movable direction α with respect to the first fingertip portion 23a. To support. In the following, the direction in which the first fingertip portion 21a grips the object (the direction approaching the second finger portion 20b) is also referred to as the “closing direction”, and the direction in which the first fingertip portion 21a releases the object (second finger). The direction away from the portion 20b) is also referred to as the “opening direction”.

  The first fingertip joint portion 22a includes a first motor (for example, an ultrasonic motor) 50a for rotating the first fingertip portion 21a in the movable direction α, and a first encoder 40a for detecting a rotation state of the first motor 50a. including.

  The first finger joint part 24 a is provided between the first finger base part 23 a and the base part 30, and supports the first finger base part 23 a so as to be rotatable in the movable direction β with respect to the base part 30. In the following, the direction in which the first fingertip part 23a grips the object (direction approaching the second finger part 20b) is also referred to as the “closing direction”, and the direction in which the first fingertip part 23a releases the object (first The direction away from the two finger portions 20b) is also referred to as the “opening direction”.

  The first finger joint part 24a detects a rotation state of a second motor (for example, an ultrasonic motor) 60a for rotating the first finger part 23a in the movable direction β and a second motor 60a. And an encoder 42a.

  Similarly, the second finger portion 20b includes a second fingertip portion 21b, a second fingertip joint portion 22b, a second fingertip portion 23b, and a second fingertip joint portion 24b. One end of the second fingertip portion 23b is connected to the base portion 30 via the second fingertip joint portion 24b, and the other end of the second fingertip portion 23b is connected to the second fingertip portion 21b via the second fingertip joint portion 22b. Connected to.

  The second fingertip joint portion 22b is provided between the second fingertip portion 21b and the second fingertip portion 23b, and the second fingertip portion 21b can be rotated in the movable direction α ′ with respect to the second fingertip portion 23b. To support. In the following, the direction in which the second fingertip portion 21b grips the object (direction approaching the first finger portion 20a) is also referred to as the “closing direction”, and the direction in which the second fingertip portion 21b releases the object (first finger). The direction away from the portion 20a) is also referred to as the “opening direction”.

  The second fingertip joint portion 22b includes a third motor (for example, an ultrasonic motor) 50b for rotating the second fingertip portion 21b in the movable direction α, and a third encoder 40b for detecting the rotation state of the third motor 50b. including.

  The second fingertip joint portion 24b is provided between the second fingertip portion 23b and the base portion 30, and supports the second fingertip portion 23b so as to be rotatable in the movable direction β ′ with respect to the base portion 30. . In the following, the direction in which the second fingertip part 23b grips the object (direction approaching the first finger part 20a) is also referred to as the “closing direction”, and the direction in which the second fingertip part 23b releases the object (first The direction away from the one finger portion 20a) is also referred to as the “opening direction”.

  The second finger joint portion 24b detects a rotation state of the fourth motor 60b (for example, an ultrasonic motor) 60b for rotating the second finger joint portion 23b in the movable direction β ′ and the fourth motor 60b. 4 encoder 42b.

  When the control unit 100 grips an object using the first finger unit 20a and the second finger unit 20b, the control unit 100 rotates each of the first finger unit 23a and the second finger unit 23b in the closing direction, The first and second motors 50a and 60a of the first finger part 20a and the second finger part 20b are configured to rotate the first fingertip part 21a and the second fingertip part 21b in the closing direction to grip the object. The third motor 50 b and the fourth motor 60 b are controlled via the drive unit 70.

  In addition, when the control unit 100 releases the object held by the first finger unit 20a and the second finger unit 20b, for example, the control unit 100 rotates each of the first fingertip unit 21a and the second fingertip unit 21b in the opening direction. The first motor 50a and the second motor 60a of the first finger portion 20a and the third motor 50b and the fourth motor 60b of the second finger portion 20b are controlled via the drive unit 70 so as to release the object. To do.

  When the control unit 100 releases the object held by the first finger unit 20a and the second finger unit 20b, the control unit 100 replaces or adds to the first fingertip unit 21a and the second fingertip unit 21b. The first motor 50a and the second motor 60a of the first finger 20a and the third motor of the second finger 20b so as to release the object by rotating the base 23a and the second finger 23b in the opening direction. You may make it control 50b and the 4th motor 60b.

  The control unit 100 grasps the rotation state (for example, the rotation position) of the first motor 50a based on the detection result of the first encoder 40a, and generates a drive command signal for the first motor 50a using the grasp result. Furthermore, the control unit 100 grasps the rotation state (for example, the rotation position) of the second motor 60a based on the detection result of the second encoder 42a, and generates a drive command signal for the second motor 60a using the grasp result. To do. Furthermore, the control unit 100 grasps the rotation state (for example, the rotation position) of the third motor 50b based on the detection result of the third encoder 40b, and generates a drive command signal for the third motor 50b using the grasp result. To do. Further, the control unit 100 grasps the rotation state (for example, the rotation position) of the fourth motor 60b based on the detection result of the fourth encoder 42b, and generates a drive command signal for the fourth motor 60b using the grasp result. To do.

  In the above configuration, when a target is gripped using a robot hand having a plurality of fingers, if the number of joints of the robot hand is large and the target is gripped using the fingers, The object may move when the finger part comes into contact with the object, and the gripping position by the finger part may shift. If the gripping position is shifted, the posture in which the robot hand grips the target object is not constant, and therefore there may be a case where the moving operation for moving the target object to a specific position or the assembling operation combined with other parts cannot be performed appropriately.

  Therefore, the robot hand 1 according to the present embodiment is characterized in that the control unit 100 performs the following operation.

  That is, the control unit 100 is included in the first finger unit 20a and the second finger unit 20b in a state where the target object is gripped using the first finger unit 20a and the second finger unit 20b and the target object is gripped. The teaching control is performed to acquire the rotational positions of the plurality of motors (that is, the first motor 50a, the second motor 60a, the third motor 50b, and the fourth motor 60b) as the teaching positions.

  The controller 100 controls the first motor 50a such that the rotational positions of the motors other than the first motor 50a that move the first fingertip portion 21a relative to the first finger base portion 23a among the plurality of motors become teaching positions. At the same time, attitude control is performed to control the first motor 50a so that the rotation position of the first motor 50a is at a position where the first fingertip portion 21a is separated from the object.

  After executing the posture control, the control unit 100 executes the closing control for controlling the first motor 50a so that the first fingertip portion 21a approaches the second finger portion 20b.

  During the execution of the closing control, the control unit 100 determines that the rotation position of the second motor 60a that moves the first finger base portion 23a relative to the base portion 30 among the plurality of motors moves the first finger base portion 23a to the second position. When it changes so that it may rotate in the direction away from the finger | toe part 20b, the teaching position of the 1st motor 50a is updated based on the rotation position of the 1st motor 50a at the time of a change having occurred.

  Furthermore, after the teaching position of the first motor 50a is updated, the control unit 100 performs the above-described posture control based on the teaching position when gripping an object, and the rotational position of the first motor 50a is determined. The closing control described above is executed so that the teaching position is reached.

  In this way, when performing an operation of gripping an object, the rotational positions of the motors other than the first motor 50a become teaching positions by posture control, so that the first fingertip portion 21a is the target during execution of the closing control. Even if it touches an object, the movement of the object can be suppressed. Furthermore, by moving the rotational position of the first motor 50a until it reaches the teaching position, it is possible to generate a constant gripping force on the object by the first finger part 20a and the second finger part 20b. For this reason, the posture of gripping the object can be made constant every time by suppressing the shift of the gripping position and generating a constant gripping force.

  FIG. 2 is a block diagram showing a configuration of a control system of the robot hand 1 according to the present embodiment. As shown in FIG. 2, the robot hand 1 further includes a drive unit 70 that drives each motor based on a drive command signal from the control unit 100.

  The control unit 100 transmits a drive command signal to the drive unit 70 when a teaching position to be described later is acquired or when a gripping operation command is received from an operator or another device. The drive unit 70 is connected to each of the first motor 50a, the second motor 60a, the third motor 50b, and the fourth motor 60b, and based on the drive command signal from the control unit 100, the first motor 50a and the second motor 60a. Then, at least one of the third motor 50b and the fourth motor 60b is driven.

  Changes in the rotation angle of the first motor 50a, the second motor 60a, the third motor 50b, and the fourth motor 60b are detected by the first encoder 40a, the second encoder 42a, the third encoder 40b, and the fourth encoder 42b, respectively. Each detection result is output to the control unit 100. Based on the detection results of the first encoder 40a, the second encoder 42a, the third encoder 40b, and the fourth encoder 42b, the control unit 100 performs the first motor 50a, the second motor 60a, and the third through the drive unit 70. The operations of the motor 50b and the fourth motor 60b are controlled.

  In the robot hand 1 having the above control system, the control unit 100 operates as follows when an unacquired teaching position is acquired or when a gripping operation command is received. The following operation of the control unit 100 may be realized by software such as a program stored in the storage unit 102 built in the control unit 100, or may be realized by hardware.

  The control unit 100 determines whether or not it is necessary to acquire a teaching position for gripping the object 80. For example, when the teaching position for gripping the object is not stored in a predetermined storage area of the storage unit 102, the control unit 100 determines that it is necessary to acquire the teaching position. On the other hand, for example, when a teaching position for gripping the object 80 is stored in the storage area of the storage unit 102, the control unit 100 determines that it is not necessary to acquire the teaching position.

  When it is determined that the teaching position does not need to be acquired, the control unit 100 determines whether there is a gripping operation command. For example, the control unit 100 may determine that there is a gripping operation command based on an operation requested by the operator, or the next operation during the operation of the robot hand 1 according to a predetermined operation pattern. It may be determined that there is a gripping motion command when a gripping motion is included in the case, or it may be determined that there is a gripping motion command when a gripping motion command is received from another device.

  The control unit 100 executes the teaching control when it is determined that the teaching position needs to be acquired.

  Specifically, as shown in FIG. 3, the control unit 100 operates the first finger unit 20 a and the second finger unit 20 b to hold the object 80. The controller 100 is in a state where the object 80 is gripped and the first encoder 40a, the second motor 60a, the second motor 60a, the third motor 50b, and the fourth motor 60b are stopped. Detection values of the encoder 42a, the third encoder 40b, and the fourth encoder 42b are acquired as teaching positions and stored in the storage unit 102.

  Hereinafter, an example of an operation for acquiring a teaching position by teaching control will be described. For example, the base 30 of the robot hand 1 is moved to a position where the object 80 can be gripped by the operation of an arm connected to the base 30.

  Positions at which the first finger unit 20a and the second finger unit 20b grip the object 80 by operating the motors of the robot hand 1 manually by the operator (the first finger unit 20a and the second finger shown in FIG. 3). Position of the portion 20b). After the movement of the first finger unit 20a and the second finger unit 20b is completed, the control unit 100 reads each of the detection values of the first encoder 40a, the second encoder 42a, the third encoder 40b, and the fourth encoder 42b. And stored in the storage unit 102 as a teaching position.

  For example, the control unit 100 moves the first finger unit 20a and the second finger unit 20b based on the provisional position information, holds the object 80 whose position is fixed, and holds the object 80. In this state, the drive command to each motor may be stopped, and the detected values of the first encoder 40a, the second encoder 42a, the third encoder 40b, and the fourth encoder 42b may be read to acquire the teaching position. In this case, for example, the control unit 100 moves the first fingertip portion 21a and the second fingertip portion 21b in the vertical direction based on the detection values of the first encoder 40a, the second encoder 42a, the third encoder 40b, and the fourth encoder 42b. The first finger base part 23a and the second finger base part 23b are moved in the closing direction so as to maintain the directed state.

  For example, the control unit 100 outputs a drive command to each of the first motor 50a, the second motor 60a, the third motor 50b, and the fourth motor 60b. It may be determined that the object 80 is grasped by the first finger portion 20a and the second finger portion 20b at a time point when the detection values of the 42a, the third encoder 40b, and the fourth encoder 42b do not change.

  After storing the teaching position, the control unit 100 stores the first finger unit 20a and the second finger unit based on the detection values of the first encoder 40a, the second encoder 42a, the third encoder 40b, and the fourth encoder 42b. The position of each movable part 20b (respective rotation positions of the first motor 50a, the second motor 60a, the third motor 50b, and the fourth motor 60b) is returned to a predetermined initial position.

  The control unit 100 executes the posture control after the teaching control is executed. Specifically, as shown in FIG. 4, the controller 100 moves the positions of the movable parts other than the first motor 50 a that rotates the first fingertip part 21 a from the initial position (the second motor 60 a, the third motor 50 b, and Each of the second motor 60a, the third motor 50b, and the fourth motor 60b is controlled so as to operate until the respective rotational positions of the fourth motor 60b reach the teaching positions stored in the storage unit 102.

  For example, the control unit 100 controls each of the second motor 60a, the third motor 50b, and the fourth motor 60b until the detection values of the second encoder 42a, the third encoder 40b, and the fourth encoder 42b coincide with the teaching position. Drive.

  On the other hand, as shown in FIG. 4, the control unit 100 sets the rotation position of the first motor 50 a that rotates the first fingertip portion 21 a to a predetermined position that is separated from the object 80 than the teaching position. The predetermined position is not particularly limited as long as the first fingertip portion 21a is separated from the object 80. The predetermined position may be a fixed value, or may be a value obtained by adding a predetermined rotation amount to the teaching position of the first motor 50a acquired by teaching control. Good.

  For example, the control unit 100 performs the above-described posture control when determining that there is a gripping operation command.

  The control unit 100 executes the closing control after executing the attitude control. As shown in FIG. 5, the control unit 100 controls the first motor 50a so that the first fingertip portion 21a operates in the closing direction. As will be described later, the control unit 100 continues the operation in the closing direction until the warp of the first finger portion 23a is detected. The control unit 100 stops the output of the drive command to the first motor 50a when the warp of the first finger base 23a is detected.

  For example, when the posture control is executed according to the gripping operation command, the control unit 100 performs the closing control until the rotational position of the first motor 50a reaches an updated teaching position, which will be described later, after the posture control is executed. Execute.

  The control unit 100 determines whether or not a warp has occurred in the first fingertip portion 23a. In the present embodiment, the warp of the first finger base portion 23a is a state in which the tip of the first fingertip portion 21a rotating in the closing direction is in contact with the side surface of the object 80 (see FIG. 6). (Refer to a solid line) refers to an operation (see a broken line in FIG. 6) in which the first finger 23a rotates in the opening direction by further rotating in the closing direction. FIG. 6 shows, as an example, a case where a large warp has occurred for convenience of explaining the warp of the first finger portion 23a.

  The control unit 100 determines whether or not the warp has occurred in the first finger portion 23a based on a change in the detection value of the second encoder 42a that detects the rotational position of the second motor 60a that rotates the first finger portion 23a. Determine. For example, when the detection value of the second encoder 42a changes in the opening direction by a threshold value or more compared to the detection value before starting the closing control, the control unit 100 causes the first finger 23a to It is determined that warpage has occurred.

  When it is determined that warpage has occurred in the first finger portion 23a, the control unit 100 updates the teaching position stored in the storage unit 102 using the detection value of the first encoder 40a at the determination time. Specifically, the control unit 100 updates the value corresponding to the first encoder 40a among the teaching positions stored in the storage unit 102 so as to be the detection value of the first encoder 40a at the determination time.

  The control unit 100 stores the teaching position acquired by the teaching control in a predetermined storage area of the storage unit 102. In addition, the control unit 100 uses the detection value of the first encoder 40a at the time when the occurrence of the warp of the first finger portion 23a is determined, and the teaching position stored in the predetermined storage area of the storage unit 102. Update.

  The control unit 100 determines that the gripping operation is completed when the occurrence of warpage is determined when posture control, closing control, and warpage determination are executed in accordance with the gripping operation command. On the other hand, for example, as illustrated in FIG. 7, the control unit 100 did not determine the occurrence of warping even though the detection value of the first encoder 40 a reached the updated teaching position by the closing control. In this case, it is determined that the object 80 does not exist at a position where it can be gripped (hereinafter, such determination may be referred to as idling determination).

  With reference to FIG. 8, the control process performed by the control unit 100 of the robot hand 1 according to the present embodiment will be described.

  In step (hereinafter referred to as “S”) 100, control unit 100 determines whether or not it is necessary to acquire a teaching position for gripping object 80. If it is determined that the teaching position needs to be acquired (YES in S100), the process proceeds to S102. If not (NO in S100), the process proceeds to S114.

  In S102, control unit 100 executes teaching control. Since the details of the teaching control are as described above, the detailed description thereof will not be repeated. In S104, control unit 100 stores the teaching position acquired by teaching control. In S106, control unit 100 executes posture control. In S108, control unit 100 executes closing control. Since the details of the posture control and the closing control are as described above, the detailed description thereof will not be repeated.

  In S110, control unit 100 determines whether or not warping has occurred in first finger portion 23a. If it is determined that warpage has occurred in first finger portion 23a (YES in S110), the process proceeds to S112. If not (NO in S110), the process returns to S110.

  In S112, control unit 100 updates the stored teaching position using the detected value of first encoder 40a at the time when it is determined that warpage has occurred in first finger portion 23a.

  In S114, control unit 100 determines whether there is a request for a gripping operation. If it is determined that there is a request for a gripping operation (YES in S114), the process proceeds to S116. If not (NO in S114), the process returns to S100.

  In S116, control unit 100 executes posture control. In S118, control unit 100 executes closing control. In S120, control unit 100 determines whether or not warping has occurred in first finger portion 23a. If it is determined that warpage has occurred in first finger portion 23a (YES in S120), the process proceeds to S122. If not (NO in S120), the process proceeds to S124.

  In S122, control unit 100 determines that the gripping operation has been completed. In S124, control unit 100 determines whether or not the rotational position of first motor 50a has reached the updated teaching position. If it is determined that the rotational position of first motor 50a has reached the updated teaching position (YES in S124), the process proceeds to S126. If not (NO in S124), the process returns to S120. In S126, control unit 100 makes an idling determination.

  An operation of control unit 100 of robot hand 1 according to the present embodiment based on the above-described structure and flowchart will be described.

  For example, if the teaching position for gripping the object 80 has not been acquired, it is determined that acquisition of the teaching position is necessary (YES in S100), and teaching control is executed (S102). The operator performs a manual operation, and the object 80 is gripped by the first finger portion 20a and the second finger portion 20b. The first encoder 40a, the second encoder 42a, and the third encoder in a state where the object 80 is gripped by the first finger portion 20a and the second finger portion 20b and the drive command to each motor is stopped. Each detected value of the encoder 40b and the fourth encoder 42b is acquired as a teaching position, and the acquired teaching position is stored (S104).

  After that, the posture control is executed after the first finger portion 20a and the second finger portion 20b are returned to the initial positions (S106). By performing the posture control, the positions of the movable parts other than the first motor 50a that rotates the first fingertip part 21a (the rotational positions of the second motor 60a, the third motor 50b, and the fourth motor 60b) are stored. Each of the second motor 60a, the third motor 50b, and the fourth motor 60b is controlled so as to operate until the taught position is reached. On the other hand, the first fingertip portion 21 a is moved to a predetermined position separated from the object 80.

  In this state, closing control is executed (S108), and the first fingertip portion 21a rotates in the closing direction. When the first fingertip portion 21a rotates in the closing direction, the tip of the first fingertip portion 21a comes into contact with the object 80, and further, the first fingertip portion 21a tries to rotate in the closing direction, whereby the first fingertip portion 23a. Will rotate in the opening direction. As a result, occurrence of warpage is determined (YES in S110), so that the detected value of first encoder 40a at the time when occurrence of warpage is determined is updated as a new teaching position for the rotational position of first motor 50a. (S112).

  If the teaching position has already been acquired, it is determined that it is not necessary to acquire the teaching position (NO in S100). At this time, when a gripping operation is requested (YES in S114), posture control is executed (S116) and closing control is executed (S118). If it is determined that warpage has occurred during the closing control (YES in S120), it is determined that the gripping operation has been completed (S122). On the other hand, if the occurrence of warpage is not determined until the rotational position of the first motor 50a reaches the updated teaching position (NO in S120, YES in S124), an idling determination is made (S126).

  As described above, according to the robot hand 1 according to the present embodiment, when the closing control is executed after the posture control, the rotation position of the second motor 60a causes the first finger base portion 23a to move to the second finger portion. The teaching position of the rotational position of the first motor 50a can be acquired when the state changes so as to rotate in a direction away from 20b. Therefore, when performing the operation of gripping the object 80, the rotational positions of the motors other than the first motor 50a become teaching positions by the attitude control, and therefore the first fingertip portion 21a is moved to the object 80 during execution of the closing control. The movement of the object can be suppressed even if it touches. Furthermore, by moving the rotational position of the first motor 50a until it reaches the teaching position, a constant gripping force can be generated on the object 80 by the first finger part 20a and the second finger part 20b. Therefore, the posture in which the object 80 is gripped can be made constant every time by suppressing the shift of the gripping position and generating a constant gripping force. Therefore, it is possible to provide a robot hand that appropriately executes a gripping operation of an object.

  Further, when it is determined that the warp does not occur during the execution of the closing control, it is determined that the object 80 is not in a position where the object 80 can be gripped. Can be determined with high accuracy.

  Furthermore, since it is not necessary to provide sensors such as a contact detection sensor at the fingertip, it is possible to suppress an increase in the size of the fingertip, and thus it is possible to grip objects of various sizes.

Hereinafter, modifications will be described.
In the present embodiment, the control unit 100 is described as performing the idling determination when the occurrence of warpage is not determined until the rotational position of the first motor 50a reaches the teaching position during the closing control. However, for example, when the occurrence of warpage is not determined before reaching the rotation position where the first motor 50a is rotated by a predetermined rotation amount from the teaching position, the idling determination may be performed.

  Further, in the present embodiment, the control unit 100 has been described as determining whether or not the warp has occurred in the first finger portion 23a during the execution of the closing control, but in the first motor 50a, at least It is desirable that a rotational torque that can generate a warp in the first finger base portion 23a is output after the tip of the first fingertip portion 21a comes into contact with the object 80.

  Furthermore, in the present embodiment, the control unit 100 teaches the detected value of the first encoder 40a at the time of occurrence as a teaching position when warping occurs in the first finger portion 23a during execution of the closing control. Although the teaching position acquired in the control has been described as being updated, for example, the closing control is executed a plurality of times, and the average value of the acquired detection values of the plurality of first encoders 40a is used as the final teaching position. The teaching position acquired in step 1 may be updated.

  Further, in the present embodiment, the control unit 100 determines the threshold value of the rotation change amount of the second motor 60a in the warpage determination when the teaching position has not been acquired and the second motor in the warpage determination when the teaching position has been acquired. Although the threshold value of the rotational change amount of 60a has been described as being the same value, for example, both threshold values may be different values. If it does in this way, adjustment of grasping force by the 1st finger part 20a and the 2nd finger part 20b will be attained. In addition, you may implement combining the above-mentioned modification, all or one part.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 robot hand, 10 hand part, 20a, 20b finger part, 21a, 21b fingertip part, 22a, 22b fingertip joint part, 23a, 23b fingertip part, 24a, 24b fingertip joint part, 30 base part, 40a, 40b, 42a, 42b Encoder, 50a, 50b, 60a, 60b Motor, 70 drive unit, 80 object, 100 control unit, 102 storage unit.

Claims (3)

A robot hand comprising a first finger part, a second finger part, and a base part to which the first finger part and the second finger part are connected, wherein the first finger part is a first fingertip part And the first finger part, the first finger part and the second finger part are operated by a plurality of motors,
A detection unit for detecting the rotational position of each of the plurality of motors;
A control device that controls the operation of the first finger unit and the second finger unit based on the rotational position of each of the plurality of motors acquired by the detection unit;
The controller is
A teaching control is performed in which an object is grasped using the first finger part and the second finger part, and each rotational position of the plurality of motors in a state of grasping the object is obtained as a teaching position. And
Among the plurality of motors, a motor other than the first motor is arranged such that the rotational position of each motor other than the first motor that moves the first fingertip portion relative to the first fingertip portion is the teaching position. Controlling the rotation position of the first motor and controlling the first motor so that the first fingertip portion is separated from the object;
After performing the posture control, performing a closing control for controlling the first motor so that the first fingertip portion approaches the second finger portion,
During the execution of the closing control, the rotational position of the second motor that moves the first finger base part relative to the base part among the plurality of motors is such that the first finger base part is moved from the second finger part. A robot hand that updates the teaching position of the first motor based on the rotational position of the first motor at the time when the change occurs when it changes to rotate in a separating direction.   When the control device grips the object after the teaching position of the first motor is updated, the control device performs the posture control based on the teaching position, and the rotational position of the first motor is updated. The robot hand according to claim 1, wherein the closing control is executed until the teaching position is reached.   When the rotation position of the second motor is changed so as to rotate in the direction separating the first finger base from the second finger during execution of the closing control, the control device The object can be gripped when it is determined that the gripping of the object has been completed and the rotation position of the second motor does not change so as to rotate in the direction separating the first finger base from the second finger. The robot hand according to claim 2, wherein the robot hand is determined not to be in a correct position.

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