JP2018075681A - Control method for holding device, holding device, robot device, and manufacturing method for component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance positioning accuracy of a position of holding an object to be held, by correcting deflections of holding parts on the basis of holding forces of the holding parts, in accordance with relative attitudes of the holding parts.SOLUTION: A control method of a holding device comprises: calculating a correction amount (ΔXref) for correcting a holding position when multiple fingers 3401 to 3403 of a hand 300 hold an object to be held to correspond to holding forces detected, for example, by force sensors 341, 342, as well as to relative attitudes that the fingers 3401 to 3403 can take, on the basis of correction coefficients (a, b) for correcting the holding position when the respective fingers 3401 to 3403 hold the object to be held; and controlling motors 311 to 313, which drive to relatively displace the respective fingers 3401 to 3403 on the basis of the calculated correction amount (ΔXref).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a gripping device control method, a gripping device, a robot device, and a component manufacturing method for controlling relative displacement of a plurality of gripping portions of a gripping device and gripping an object by the gripping portion.

  In recent years, there has been an increasing demand to automate the assembly process of industrial products such as cameras and printers that have been performed manually by an industrial robot. The parts that make up these products are many small precision parts, and have a wide variety of shapes and materials. In this type of product and component production line, a system that combines a robot arm with a multi-joint arm and a gripping device such as a robot hand is used. Particularly recently, due to the demand for multi-purpose engineering and setup change due to high-mix low-volume production, these robot arms and robot hands are required to be versatile enough to handle workpieces of different shapes and sizes. It was. Further, when assembling the workpiece, the hand as the gripping device needs to stably position the workpiece as the gripping object at the target gripping position.

  A visual system such as a camera may be used to position a specific part of the workpiece with respect to the reference position of the robot hand, for example, the center axis of the hand. In addition, a method for controlling a gripping force and a gripping position according to a work shape or the like by making it possible to set a finger for position control and a finger for force control by the value of a force sensor mounted on the hand has been proposed. (For example, the following patent document 1).

  If one finger of the hand is regarded as one manipulator, this type of robot hand is usually composed of two or more manipulators. Generally, in this type of hand drive mechanism, when a force is generated at the tip of the manipulator, bending is generated by a spring element such as a speed reducer or a link of each joint, and an error occurs in the positioning accuracy of the manipulator tip. In view of this, a technique has been proposed in which the deflection is corrected using the output of a force sensor that detects the gripping force of the hand and the rigidity information of the workpiece or manipulator (for example, Patent Document 2 below).

JP 2010-69584 A JP2013-255981A

  In the force control and position control described in Patent Document 1, gripping control does not consider gripping position errors due to bending of a workpiece or a finger of a hand. The grip control described in Patent Document 2 is a deflection correction in units of one manipulator, and when this configuration is applied to a multi-finger robot hand, force sensors are mounted on all fingers. Become. Such a configuration is expected to make it difficult to reduce cost, size, and weight.

  In addition, when a gripping device such as a robot hand has a plurality of fingers that open and close as a gripping unit, the relative posture in which each finger is relatively displaced according to gripping conditions such as the shape and dimensions of the workpiece of the gripping target It is possible to prepare different hands. In addition, a configuration of a robot hand that enables such a posture adjustment is conceivable, and a configuration of a robot hand that can dynamically change the posture of relative displacement is also conceivable. In such a configuration, the control load that is dynamically executed by the control device may increase in the configuration using the gripping force of each finger as in Patent Document 2.

  An object of the present invention is to make it possible to improve the positioning accuracy of the gripping position of the gripping object by correcting the bending of the gripping part based on the gripping force corresponding to the relative posture of the gripping part.

  In order to solve the above problems, for example, in the control method of the present invention, the relative displacement amounts of the plurality of gripping units are controlled according to the gripping force with which the plurality of gripping units grip the gripping target, and the gripping target In the control method of the gripping device for controlling the gripping position, based on the gripping force and a correction coefficient for correcting the gripping position according to the gripping force corresponding to the relative postures of the plurality of gripping units, A configuration including a correction amount calculation step of calculating a correction amount for correcting the gripping position and a drive control step of controlling a drive source that relatively displaces the gripping portion based on the correction amount is adopted.

  According to the above configuration, it is possible to correct the deflection of the gripping part based on the gripping force corresponding to the relative posture of the gripping part and improve the positioning accuracy of the gripping position of the gripping object.

It is explanatory drawing which showed schematic structure of the robot system which can employ | adopt this invention. It is explanatory drawing which showed schematic structure of the hand as a holding | grip apparatus which can employ | adopt this invention. It is the block diagram which showed the outline of the control system of the apparatus of FIG. It is the block diagram which showed schematic structure of the correction | amendment calculation part of FIG. It is explanatory drawing which showed an example of the workpiece | work kind which concerns on Embodiment 1 of this invention, and its holding | grip method. It is explanatory drawing which showed an example of the holding | grip command table which concerns on Embodiment 1 of this invention. It is explanatory drawing which showed an example of the correction coefficient table which concerns on Embodiment 1 of this invention. It is a flowchart figure which shows the process sequence which correct | amends the bending of the fingertip position of a hand in the hand control apparatus which concerns on Embodiment 1 of this invention. It is a flowchart figure which shows the holding | grip control procedure containing the bending correction which concerns on Embodiment 1 of this invention. It is a block diagram of the motor control part which concerns on Embodiment 1 of this invention. It is explanatory drawing which showed an example of the workpiece | work which concerns on Embodiment 2 of this invention, and its holding | grip method. It is explanatory drawing which showed an example of the holding | grip command table which concerns on Embodiment 2 of this invention. It is a flowchart figure which shows the holding | grip control procedure containing the bending correction which concerns on Embodiment 2 of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to embodiments shown in the accompanying drawings. The following embodiment is merely an example, and for example, a detailed configuration can be appropriately changed by those skilled in the art without departing from the gist of the present invention. Moreover, the numerical value taken up by this embodiment is a reference numerical value, Comprising: This invention is not limited.

<Embodiment 1>
In the present embodiment, a configuration of a gripping device that controls a relative displacement amount of the plurality of gripping units according to a gripping force by which a plurality of gripping units grips a gripping target, and controls a gripping position of the gripping target; And control method. In the following embodiments, the gripping device and the gripping unit correspond to a robot hand (hereinafter referred to as a hand) and its fingers.

  The gripping force by a plurality of fingers of the hand may be calculated by a control device (for example, a CPU 501 described later) by calculation based on the driving force (for example, driving power, current or servo control information) of a driving source that controls the relative displacement of the fingers. . However, in this embodiment, actual measurement is performed with a force sensor arranged on the finger of the hand. As a result, it is possible to perform control in accordance with the gripping state. The force sensor may be a load cell, a strain gauge, or a force detection device that optically measures the amount of deformation of the detection unit. Further, in the present embodiment, it is not necessary to arrange force sensors on the fingers of all the hands as in the above-described conventional configuration (Patent Document 2), and it is arranged on at least one of the fingers used for grasping the object. Just do it.

  In the grip control of the gripping device of the present embodiment, gripping is performed based on the gripping force and a correction coefficient for correcting the gripping position of the object according to the gripping force corresponding to the relative postures of the plurality of gripping units. A correction amount for correcting the gripping position of the object is calculated (correction amount calculation step). Then, based on the calculated correction amount, a drive source that relatively displaces the gripper is controlled (drive control step). It is also conceivable that the above-described correction coefficient is dynamically obtained by a control device (for example, a CPU 501 described later) dynamically according to the grip pattern, particularly the relative posture of each finger. However, in this embodiment, a value corresponding to the relative posture of each finger is stored in advance in a storage device (ROM 502, RAM 503, etc.).

  As described above, with respect to the relative displacement of each finger of the hand, a hand having a different relative posture when each finger of the hand is relatively displaced is prepared according to the gripping conditions such as the shape and dimensions of the workpiece of the gripping object. It is possible. Alternatively, a configuration of a robot hand that enables such a posture adjustment is conceivable, and a configuration of a robot hand that can dynamically change the posture of relative displacement is also conceivable. In any case, a correction coefficient for correcting the grip position of the grip target is stored in advance in a storage device (ROM 502, RAM 503, etc.) in association with a grip pattern that may be implemented, particularly for each finger relative posture. By doing so, the gripping position can be corrected.

  Hereinafter, a configuration in which a gripping pattern, in particular, a posture control unit that changes the relative posture of each finger, particularly a turning mechanism such as joints J4 and J5 described later is arranged in the hand will be exemplified. When the relative posture of each finger is changed by the posture control device, particularly the turning mechanism, the control device (for example, CPU 501 described later) selects a correction coefficient corresponding to the relative posture and selects the gripping target object. Control to correct the gripping position is performed.

  Hereinafter, the configuration and grip control in the first embodiment will be described with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of a robot system of this embodiment using the hand control device of the present invention.

[Robot system]
The robot system 100 of this embodiment includes an arm main body 200, a hand 300, an arm control device 400, and a hand control device 500. The work W1 that is an assembly part is placed on the work placing table S1, and the work W2 that is an assembly target is fixed on the work fixing base S2.

  By manipulating and assembling the workpieces W1 and W2 by the robot system 100, industrial products or parts thereof can be manufactured. For example, the assembly operation for the workpieces W1 and W2 is performed by gripping and moving the workpiece W1 as a gripping object using the arm body 200 and the hand 300, and further fitting the workpiece W1 to the assembly portion of the workpiece W2. It is performed by such operations.

  The arm main body 200 is an articulated robot arm in this embodiment, and the base of the arm main body 200 is fixed to the base 600, and a hand 300 as a gripping device is attached to the tip of the arm main body 200 as an end effector. The An operation is performed on the workpiece W1 through the hand 300. Each joint of the arm body 200 is provided with a motor (not shown) as a drive source for driving the joints, and an encoder (not shown) as a detector for detecting the rotation angle of the motor.

  The arm control device 400 calculates an angle to be taken by each joint of the arm main body 200 with respect to a target position / posture of the arm tip to which the hand 300 used in assembly is moved, and controls a motor (not shown) of each joint. A command value is output to a servo circuit (not shown). The arm control device 400 is connected to the hand control device 500 and outputs a grip command to the hand 300. This gripping command can be output as, for example, a number, that is, numerical expression data. Although details of the arm control device 400 are not shown, the arm control device 400 can be configured by a CPU, ROM, RAM, a general-purpose signal interface, a motor driver, and the like, similar to the configuration indicated by 500 to 505 of the hand control device 500 described later. Among them, the general-purpose signal interface communicates with sensors and the like of each part of the arm body 200, and the motor driver is used to control a motor that drives each joint of the arm body 200.

  FIG. 2 shows a schematic configuration of the hand 300 according to the first embodiment. The hand 300 has three fingers (finger) fingers 3401 to 3403 (first to third fingers) as a gripping portion.

  These fingers 3401 to 3403 are controlled so as to be displaced relative to each other by the links 351, 352, and 353 and the joints J1 to J5 that are rotationally driven, thereby grasping or grasping an object to be grasped (each work described later). Operates to open. In this configuration, there are five joints J1 to J5. Therefore, the fingers (3401 to 3403) of the hand 300 are driven by these joints J1 to J5 having a total of 5 degrees of freedom.

  The links 351 to 353 constituting a part of each finger (3401 to 3403) drive transmission system of the hand 300 are so-called parallel four-bar linkage mechanisms as shown in the figure, for example. With this configuration, the fingers (3401 to 3403) can be opened and closed while maintaining a parallel posture, for example.

  Links 351, 352, and 353 for controlling the relative displacement of each finger (3401 to 3403) are driven by joints J1, J2, and J3, respectively.

  In the present embodiment, two fingers 3402 and 3403 (second finger and third finger) out of the three fingers are configured to be driven to rotate by joints J4 and J5 having one degree of freedom, respectively. Accordingly, the turning posture of the fingers 3402 and 3403 (second finger and third finger) with respect to the finger 3401 (first finger) can be controlled. Accordingly, for example, as shown in FIG. 5 described later, the gripping form of the fingers 3401 to 3403 can be changed according to various workpiece shapes.

  The driving mechanism for the fingers 3401 to 3403 is supported on the base 36 of the hand 300 attached to the tip of the arm body 200. The xyz coordinate system shown in FIG. 2 is a hand coordinate system in which the center axis 361 of the base portion 36 passes, for example, one point on the upper surface of the base portion 36 as an origin.

  In FIG. 2, the support portion 363, which is simply illustrated by a straight line so as to connect the joints J <b> 4 and J <b> 5 of the fingers 3402 and 3403, is supported on the central axis 361 of the base portion 36 in parallel with the y axis of the hand coordinate system (xyz), for example. The For convenience, the joint J1 of the finger 3401 is supported at the same height as the joints J4 and J5 on the base portion 36 via a support portion 362 illustrated in an L shape.

  The joints J4 and J5 may be operated independently of each other, but in the present embodiment, the joints J4 and J5 are driven in reverse rotation with each other by the same drive amount. Thereby, in this embodiment, it is controlled so that the fingers 3402 and 3403 (second finger and third finger) always take a symmetrical turning posture with respect to the finger 3401 (first finger). In the present embodiment, the turning angle of the fingers 3402 and 3403 by the joints J4 and J5 is expressed using the angle of the joints J4 and J5 parallel to the y axis with respect to the support portion 363 for convenience.

  For example, the illustration of FIG. 2 shows a three-finger facing arrangement when the joints J4 and J5 are each 90 ° with respect to the support portion 363 (or the y-axis). Further, the angle when the joints J4 and J5 are rotated from the state of FIG. 2 by 90 ° in the direction of the arrow in the drawing is expressed as 0 ° below. Further, the angle when the joints J4 and J5 are rotated from the state of FIG. 2 by 60 ° in the direction of the arrow in the drawing is expressed as 30 ° below. In the present embodiment, for example, with reference to FIG. 5 described later, the numerical values as described above may be expressed for the rotation angles of the joints J4 and J5.

  In FIG. 2, motors 311 to 315 are provided at the joints J1 to J5 of the hand 300 as driving means for driving the joints. The finger links are driven via speed reducers 321 to 325 directly connected to motors 311 to 315, respectively. The speed reducers 321 to 325, the force sensors 341 and 342, and the link of each finger have a spring property (elasticity) in the gripping direction, and the fingertip position is corrected by bending correction described later. In addition, the motors 311 to 315 are provided with encoders 331 to 335 that detect the rotation angles of the motors.

  A control device, for example, a CPU 501 described later, can calculate the rotation angles of the joints J1 to J5 using the output values of the encoders 331 to 335. In that case, a control device, for example, a CPU 501 described later, can convert the output values of the encoders 331 to 335 into the rotation angles of the joints J1 to J5 using the reduction ratios of the speed reducers 321 to 325.

  In this embodiment, force sensors 341 and 342 are provided at the tips of fingers 3401 and 3402 (first finger and second finger), respectively, and the gripping force applied to these fingers can be detected. However, in this embodiment, the force sensor should just be arrange | positioned at one finger | toe used for the holding | grip of the holding object at least. In the present embodiment, the force sensors 341 and 342 are provided on the fingers 3401 and 3402 because at least one part of the plurality of fingers is included depending on a plurality of grip patterns in which the relative postures of the fingers differ when gripping an object described later. This is because the gripping force can be detected by a single finger force sensor. However, the configuration in which the force sensor 343 is also arranged on the finger 3403 as shown in FIG. 2 in parentheses according to the specifications of the form of the work and the gripping mode that can be executed by the hand 300 (a gripping pattern described later). It may be. Accordingly, there is a possibility that the gripping mode (a gripping pattern described later) that can be executed by the hand 300 can be expanded according to the form of the workpiece.

  As shown in FIG. 1, the hand control device 500 includes a CPU 501 including a microprocessor and the like, and a ROM 502, a RAM 503, a general-purpose signal interface 504, a motor driver 505, and the like connected to the CPU 501 by a bus. The ROM 502 stores a program for controlling the hand 300 (including a program for performing deflection correction described later).

  A gripping command table 511, which will be described later, and a correction coefficient table 512 storing correction coefficients for each specific relative posture when the relative posture of each finger of the hand 300 is changed may be arranged in a storage area of the RAM 503, for example. it can. Alternatively, these tables (511, 512) may be arranged in the storage area of the ROM 502 if these table memories can be ROMized according to the mounting specifications of the apparatus.

  Further, the RAM 503 is also used as a temporary storage memory when the CPU 501 executes an operation and as a register area set as necessary. The general-purpose signal interface 504 functions as an input / output device for the arm control device 400 and the like. Based on the motor current command value calculated by the CPU 501, the motor driver 505 supplies current to the 5-axis motors 311, 312, 313, 314, 315 that controls the opening / closing (relative displacement) and turning of each finger of the hand 300. Supply current with control.

  In this embodiment, the arm control device 400 and the hand control device 500 are shown as separate control devices, but these control devices may be integrated depending on the implementation of the robot apparatus. That is, one common control device for controlling the arm main body 200 and the hand 300 is arranged, and in this embodiment, the control described as the control executed by the arm control device 400 and the hand control device 500 is performed by this common control device. It may be configured to execute. This configuration can be considered as a configuration in which the hand control device also controls the robot arm, and conversely, the robot arm control device also controls the hand.

  FIG. 6 shows an example of the configuration of the grip command table according to the present embodiment. The grip command table 511 in FIG. 11 mainly includes fields for the entire hand setting 6001 and the control parameters 6002 for each joint, and records storing grip patterns, modes, and control parameters for each grip command number are arranged. (6003). In the hand whole setting 6001 portion, a grip pattern and a grip mode are stored for each grip command number. The control parameter 6002 stores items of position command values and force command values of the joints J1, J2, J3, J4, and J5 of the hand 300.

  Note that the suffix notation in the mathematical formulas and the like described later is not necessarily in the sentence excluding the mathematical formulas in this specification or in each figure, considering the legibility and having little possibility of error. Suffix notation shall not be used.

  In FIG. 6, the grip pattern is data describing whether position control (P) or force control (F) of the joints J1 to J5 of the hand 300 is performed. In this embodiment, the joint for position control is P, the joint for force control is F, and the order of symbols (P, F) is made to correspond to each motor number. In the present embodiment, the following three types of grip patterns are set. That is, [PPPPP (position control of all joints)], [FPPPP (force control only for joint J1, and remaining joints J2, J3, J4, J5 are position control)], [PFPPP (force control only for joint J2, remaining control) There are three types of joints J1, J3, J4, and J5: position control))]. In particular, when the grip pattern is [FPPPP], it is applied to gripping with three fingers, and when it is [PFPPP], it is applied to gripping with two fingers.

  In this embodiment, data indicating either outer shape gripping or inner shape gripping is set in the gripping mode field. The external gripping is a gripping mode in which a workpiece is gripped from the outside by a plurality of fingers of the hand 300, and the internal gripping is a gripping mode in which the workpiece is gripped from the inside (see FIG. 5).

  Note that the above-described gripping pattern and gripping mode (outer shape gripping / inner shape gripping) may be considered as direction information of gripping force for gripping a workpiece as a gripping object by each finger of the hand 300.

  Further, in the position command value and force command value fields of the joints J1, J2, J3, J4, and J5, the position command value of the motor of the driving source is F in the grip pattern in the joint for which P is set in the grip pattern. The force command value is set for the motor at the joint for which is set. The position command value of each motor is set to a value corresponding to the gripping stroke (unit: mm) in the case of joints J1, J2, J3 that open and close (relative displacement) each finger. In the case of the joints J4 and J5, a value corresponding to the angle at which the joint is held is set (unit deg). The force command value for each joint is set to a value corresponding to the gripping force generated at the tip of each finger (unit N). In the present embodiment, the specifications are such that only the joints J1 and J2 can perform force control by setting a force command value.

  In FIG. 6, the position command value and the initial value Xref before correction of the force command value are stored in the finger whose position is controlled and the finger whose force is controlled. Here, in FIG. 6, the command number (1) ([PPPPP]) corresponds to the case where the positions of all the joints are controlled according to the size of the workpiece and the shape of the details, and the initial values Xref of the position command values are all 0. Further, for example, command number (2) ([FPPPP]: force control only for joint J1) sets joints J4 and J5 to 30 ° (deg) (corresponding to three fingers equally gripping work W1a in FIG. 5). Control. In the grip control of the command number (2) ([FPPPP]: force control only for the joint J1), the initial value Xref of the force command value of the joint J1 is 10 (N), and the initial position command values of the other two finger joints. The value Xref is 0 (mm).

  In the grip command table of FIG. 6, various control parameters corresponding to selectable grip commands can be arranged in association with the grip command numbers in accordance with the control specifications of the hand 300.

  FIG. 7 shows an example of the configuration of the correction coefficient table according to the present embodiment. The correction coefficient table 512 stores correction coefficients a2, b2, a3, and b3 (7004) according to the combination of each of the grip pattern (7001), the grip mode (7002), and the position command values (7003) of the joints J4 and J5. To do.

  In this embodiment, it is assumed that one finger is subjected to force control and the other two fingers or one finger is subjected to position control, and the correction coefficient table 512 in FIG. 7 is expressed by an expression (for example, expressions (2) to (4)) described later. The correction coefficients a2, b2, a3, b3 for calculating the correction amount (ΔX) are stored. The first suffix of the correction coefficient a or b corresponds to the first to third finger numbers.

  Further, the numerical values a21 to a24, b21 to b24, a31 to a36, and b31 to b36 (actual values) of the correction coefficients a2, b2, a3, and b3 set in the correction coefficient table 512 of FIG. Find in advance. The second suffix of these correction coefficients a or b corresponds to a data number determined to increase gradually according to the arrangement order of the table for convenience.

  As calibration methods for obtaining the correction coefficients a2, b2, a3, b3 numerical values a21 to a24, b21 to b24, a31 to a36, b31 to b36 (actually numerical values), the gripping pattern, the gripping mode, the positions of the joints J4 and J5 The correction coefficient is divided according to each case of the command value. Then, according to each case, measure the amount of deflection using the reference workpiece within the gripping force in the range used for assembly, and cancel the amount of deflection caused by the least square method. The correction coefficients a2, b2, a3, and b3 are calculated so as to obtain a correct correction amount.

  FIG. 3 shows a schematic configuration of a control function (control process) of the hand control device 500 in the form of a pseudo block diagram. The control function (control process) of the hand control device 500 includes a correction amount calculation unit 520 (correction amount calculation process). In addition, as a drive control function (drive control process) that controls a drive source that relatively displaces the gripping part (each finger) according to the correction amount acquired by the correction amount calculation unit 520 (correction amount calculation step), a command value generation unit 530, motor control units 541 to 545, and a motor driver 505 are included.

  When the hand 300 grips the workpiece W1 by force control, the correction amount calculation unit 520 calculates the correction amount of the finger whose position is controlled according to a deflection correction method described later. Based on the grip command and grip command table 511, the command value generation unit 530 controls the control mode (position control or force control) for each motor 311 to 315 and the command value to each motor 311 to 315 for each motor control. To the units 541 to 545. The command values for the motors 311 to 315 are position command values when the control mode for the motors 311 to 315 is position control, and force commands when the control mode for the motors 311 to 315 is force control. Value.

  In the present embodiment, for convenience, only position control or force control can be selected for only the motors 311 and 312 of the joints J1 and J2, and the motors 313 to 315 of the joints J3, J4 and J5 can only be position control. It shall be a possible specification. In addition, when the hand 300 grips the workpiece W1 by force control, the command value generation unit 530 corrects the position command value based on the correction amount calculated by the correction amount calculation unit 520, and then sets each motor control unit 541-541. To 545.

  The motor control units 541 to 545 of each motor pass the current command values of the motors 311 to 315 to the motor driver 505 according to the control mode passed from the command value generation unit 530. Since the functions of the motor control units 541 to 545 are the same, and the configuration of each of these motor control units is shown here, the configuration of the motor control unit 541 of the joint J1 is shown in FIG.

  In FIG. 10, when the control mode for the motor 311 is position control, the position control unit 546 performs feedback control based on the position command value and the value from the encoder 331, and outputs a current command value. When the control mode for the motor 311 is force control, the force control unit 547 performs feedback control based on the force command value and the value from the force sensor 341, and outputs a current command value. The control mode switching unit 548 includes an analog switch and a multiplexer, and selects a current command value of the position control unit 546 or the force control unit 547 based on a control mode for the motor 311 and outputs the current command value to the motor driver 505. .

  FIG. 4 shows a functional configuration of the correction calculation unit (correction amount calculation step) according to the present embodiment. In FIG. 4, the correction amount calculation unit 520 includes a correction coefficient selection unit 521 and a correction amount calculation unit 522. Based on the grip command number and grip command table 511 (FIG. 6) transmitted from the arm control device 400, the correction coefficient selection unit 521 determines the grip pattern, grip mode, and joints J4 and J5 corresponding to the grip command number. An initial value (Xref) of the position command value is extracted.

  Next, a corresponding correction coefficient is selected based on the extracted gripping pattern, gripping mode, position command values of the joints J4 and J5, and the correction coefficient table 512. The correction amount calculation unit 522 calculates the deflection correction amount (ΔXref) of the finger whose position is to be controlled based on the correction coefficient selected by the correction coefficient selection unit 521, the force command value and the position command value in the grip command table 511. .

  Here, the work W1 of FIG. 1 has an assembly part (concave part) for fitting with the work W2. Moreover, the workpiece | work W2 has an assembly | attachment part (convex part) for fitting with the workpiece | work W1. The robot apparatus of FIG. 1 grips the workpiece W1 with the hand 300, and in that state, the arm body 200 transports the workpiece W1 to a position where the assembly portion of W2 and both is aligned, and the two are fitted (assembled). Append)

  Here, FIG. 5 is an explanatory diagram showing an example of a work type according to the present embodiment. In the present embodiment, it is assumed that the workpiece W1 gripped by the hand 300 has three types of shapes (5001: workpiece W1a, workpiece W1b, workpiece W1c). FIG. 5 shows a gripping form (5002), a gripping pattern (5003), and a control form (5004) for each work type (5001).

  In the simplified illustration of the control mode (5004), the horizontal one-dot chain line in the figure corresponds to the y-axis direction in FIG. 2, and the vertical one-dot chain line corresponds to the X-axis direction in FIG. In the drawing of the grip control form (5004), the force-controlled finger (3401 or 3402) and the position-controlled finger (3402 and 3403) are distinguished by the presence or absence of a broken line according to each work type.

  Here, the workpiece W1a is a cylindrical or spherical object to be gripped and is an object having a circular cross section, and the gripping form (5002) of the hand 300 is three fingers equally distributed (both joints J4 and J5 are 30 °). The gripping mode of 300 is gripped as external gripping. Since the workpiece W1a is gripped by three fingers, [FPPPP] is selected as the gripping pattern (5003). The workpiece W1b is a rectangular object, and grips the gripping mode of the hand 300 with three fingers facing each other (joint J4 and J5 are both 90 °), and grips the gripping mode with external gripping. Since the workpiece W1b is gripped by three fingers, [FPPPP] is selected as the gripping pattern.

  In addition, the workpiece W1c is a rectangular object, and the gripping mode of the hand 300 is opposed to two fingers (joints J4 and J5 are both 0 °), and the gripping mode is gripped with an internal gripping. Since the workpiece W1c is gripped by two fingers, [PFPPP] is selected as the gripping pattern.

  Here, in this embodiment, for example, control for correcting the gripping position by correcting the deflection of the finger position when gripping the workpiece W1 performed by the hand control device 500 will be described. In this embodiment, position correction is performed only in the gripping direction.

  The grip control in the present embodiment is roughly configured by control as shown in the flowchart of FIG. The grip control in FIG. 8 can be described as a control program that can be executed by the CPU 501 of the hand control device 500, for example. In this case, this control program can be stored in, for example, the ROM 502 (or an external storage device such as an HDD or various flash memories).

  In the grip control of FIG. 8, the hand control device 500 first calculates a deflection correction amount from a force command value that is a grip force by the correction amount calculation unit 520 (step S10). The correction amount ΔXrefi (i = 2, 3) of the finger (i-th finger) whose position is to be corrected is calculated by a correction operation as shown by the following mathematical formula.

  Next, the position command value X′refi corrected by the command value generation unit 530 based on the correction amount ΔXrefi (i = 2, 3) is calculated by, for example, the following equation (1), and each motor control unit 541 is calculated. To 545 (step S20).

  However, in the above equation (1), Xrefi is a position command value before correction of the finger (i) whose position is corrected. This position command value Xrefi corresponds to the command value (initial value) illustrated in FIG.

  Subsequently, the motor control units 541 to 545 operate the hand 300 based on the command value X′refi (step S30).

  Here, step S10 will be described in more detail with reference to FIG. First, the correction coefficient selection unit 521 selects a correction coefficient with reference to the correction coefficient table 512 of FIG. 7 (step S11). For example, in the case of the correction coefficient table 512 of FIG. 7, when gripping the workpiece W1a, a21, b21, a31, and b31 (actually numerical values) are selected as the correction coefficients a2, b2, a3, and b3, respectively.

  Similarly, when gripping the workpiece W1b, a22, b22, a32, b32 (actually numerical values) are selected as the correction coefficients a2, b2, a3, b3, respectively, and when gripping the workpiece W1c, the correction coefficients a3, b3 are selected. , A36, b36 (actually numerical values) are selected.

  Next, the correction amount is calculated from the correction coefficient and the gripping force in the correction amount calculation unit 522 (step S12). For example, when gripping the workpiece W1a, the correction amounts ΔXref2, ΔXref3 are calculated by, for example, the following equation (2).

  Here, the gripping force generated on the finger 3401 (first finger) is assumed to be Fref1. It is assumed that the initial value of the position command and the correction amounts Xref and ΔXref are the displacement amounts along the moving direction when each finger is moved in the gripping (closing direction). The relative displacement amount when each finger is relatively displaced is determined by these position command values.

  Further, when gripping the workpiece W1b, the correction amounts ΔXref2 and ΔXref3 are calculated by the following equation (3), for example.

  Similarly, when gripping the workpiece W1c, the correction amount Xref3 is calculated by Equation 4.

  At this time, the gripping force generated on the finger 3402 (second finger) is Fref2.

  In the above grip control, the workpiece W1a and the workpiece W1b are the same three-finger grip, but the angles of the joints J4 and J5 are different. For this reason, even if the workpiece W1a and the workpiece W1b are held with the same gripping force, the bending generated in the fingers 2, 3 is different. Therefore, different correction coefficients (a2, b2, a3, b3) are read from the correction coefficient table 512 and used as described above. Thereby, appropriate gripping position correction can be performed according to the relative posture of each finger (each gripping part).

  According to the hand control device 500 of the present embodiment, it is possible to perform grip control including the above-described deflection correction. For this reason, as shown in FIG. 5, even with respect to gripping forms having different joints J4 and J5, highly accurate gripping position correction can be performed, and the positioning accuracy of the workpiece can be greatly improved. In addition, the force sensor for detecting force may be disposed on at least one finger that actually acts on gripping. For example, it is not necessary to dispose force sensors on all fingers, and the hardware configuration is simple and inexpensive. That's it. Further, for example, it is possible to perform hand control with high speed and high responsiveness without requiring a complicated control process in which the position control amount is determined according to the force control state of all fingers.

  As for the external grip and the internal grip, the speed reducers 321 to 325 generally have backlash, so that even if the same gripping force is held, there is a possibility that a difference occurs in the amount of bending of the fingertip. However, according to the hand control device 500 of the present embodiment, different correction coefficients are stored in the correction coefficient table 512 according to the difference in gripping mode such as outer gripping and inner gripping. For this reason, even if there is a backlash in the joints J1 to J5 of the hand 300, highly accurate gripping position correction can be performed, and the positioning accuracy of the workpiece can be improved. Here, for example, when gripping with a gripping force of 10 N, if the stiffness coefficient of the drive system of each finger converted to the tip of the fingertip is 50 N / mm, the deflection amount of the fingertip is about 10 N / (50 N / mm) = 0.2 mm Occurs on the order of By using the deflection correction of this embodiment, the workpiece positioning accuracy can be improved by about 0.2 mm.

  As described above, according to the present embodiment, the deflection of the finger position due to the gripping force can be corrected by the hand 300, the highly accurate gripping position correction can be performed, and the workpiece positioning accuracy can be improved. According to the present embodiment, by appropriately creating the correction coefficient table 512, it is possible to perform highly accurate gripping position correction according to the mechanical specifications of the hand. For example, even in the case of a hand having a long and narrow tip for handling a fine work and a hand having a large elasticity for protecting the work, the gripping position can be corrected appropriately and accurately depending on the configuration. This means that the gripping position can be corrected appropriately and with high accuracy according to the configuration even in a hand or the like using a wave gear that is easily twisted when the torque is applied to the speed reducer. A similar effect can also be expected for a hand equipped with a force sensor that requires the sensor to bend by that force in order to detect the gripping force of the fingertip.

  Further, in an actual product or part production line, it is expected that the command initial value (each Xref) of the gripping force of the hand at the time of assembly is changed in order to shorten the cycle time of the assembly process. According to the present embodiment, even when such a change occurs, the workpiece can be gripped without deteriorating the positioning accuracy of the workpiece, and assembly can be performed without adjusting the position of the arm.

  Moreover, the hand shown in said embodiment can be used for a robot arm, the workpiece which is a target object can be hold | gripped, and the manufacturing line which assembles an industrial product or its components can be comprised. In this case, according to the present embodiment, the workpiece gripping position accuracy can be greatly improved, and a high-speed and high-precision product or component assembly operation can be automatically executed.

<Embodiment 2>
In the first embodiment described above, conditions such as the rigidity (or elasticity) of the workpiece (W1) are not taken into account, and the workpiece (W1) is not deformed by the gripping force, and the workpiece dimensions are determined with no variation. It was assumed that. However, the present invention can be implemented in the case where a workpiece as a gripping object is deformed by a gripping force of a hand as a gripping device and there is a possibility that variations in workpiece dimensions may occur.

  The second embodiment exemplifies gripping control for correcting the gripping position using the stiffness coefficient of the workpiece that is the gripping object. In the second embodiment, for example, the stiffness coefficient of the workpiece is known, the dimension in the gripping direction of the workpiece includes variation within a tolerance range, and the workpiece is to be positioned at a predetermined gripping position (for example, the center position of the hand). In some cases.

  FIG. 11 shows an example of a workpiece according to the second embodiment in the same manner as in FIG. Hereinafter, as a second embodiment, grip control in the case of assembling the workpiece W1d as illustrated in FIG. 11 will be described. In the following, regarding the configuration of the hardware and the control system, different portions will be shown and described, and the same configuration and operation as those described above will be possible for the same portions as the first embodiment, and detailed description thereof will be given. Shall be omitted.

  In the following description, the same or similar reference symbols are used for the same or equivalent members and control functions as in the first embodiment. In particular, the hardware configuration relating to the arrangement of the joints and force sensors of the hand 300 is the same as that shown in FIG.

  The workpiece W1d has an assembly portion (concave portion) for assembling the workpiece W2 in the same manner as the workpiece W1 of FIG. The workpiece W1d is, for example, an object having a rectangular cross section (work type: 5001), the gripping form (5002) of the hand 300 is opposed to two fingers (joint J4 and J5 are both 0 °), and the gripping pattern (5003) is external gripping. To do. As shown in the grip control form (5004), the workpiece W1d is gripping with two fingers, and [PFPPP] is selected as the control pattern. Also, it is assumed that the workpiece W1d has variations in dimensions in the direction of gripping with two fingers and three fingers. The workpiece W1d is not a rigid body but has a spring property, and in this embodiment, has a stiffness coefficient of 10 N / mm.

  In this embodiment, similarly to the first embodiment, the robot system 100 is used, and the robot system 100 includes an arm main body 200, a hand 300, an arm control device 400, and a hand control device 500. Similarly, the workpiece W1d, which is an assembly component, is placed on the workpiece mounting table S1, and the workpiece W2, which is an assembly target object, is fixed on the workpiece fixing table S2. Similarly, the workpiece W1d and the workpiece W2 are assembled by moving the workpiece W1d using the arm main body 200 and the hand 300 to fit the workpiece W1d to the assembly portion of the workpiece W2.

  The differences from the first embodiment are the hand control device 500 and the workpiece W1d. Below, the hand control apparatus 500 and workpiece | work W1d which are different from Embodiment 1 are demonstrated. As in the first embodiment, the hand control device 500 includes the CPU 501, ROM 502, RAM 503, general-purpose signal interface 504, motor driver 505, and the like shown in FIG. A part different from the first embodiment is information stored in the ROM 502 and the RAM 503. The ROM 502 stores a control program for the hand 300 that realizes the deflection correction in the second embodiment to be described later. The RAM 503 stores a grip command table 511 ′ and a correction coefficient table 512.

  In the present embodiment, the grip command table 511 'is configured as shown in FIG. FIG. 12 shows the contents of the grip command table 511 ′ in the same format as FIG. 6 (grip command table 511) of the first embodiment. Here, as a field of the control parameter 6002 of each joint of the grip command table 511 ′, particularly the rightmost field, in addition to the content of the grip command table 511 of FIG. 6, a field of rigidity coefficient of the work W1d is added as work information. It has become. As described above, in FIG. 12, in the field of the stiffness coefficient, the stiffness coefficient (unit N / mm) of the workpiece (W1d) gripped by the grip control corresponding to the grip command number (2) is 10 ( N / mm) is stored. In particular, in the grip control of the grip command number (2), the positions of the joints J1, J3 to J5 are controlled to 0 mm, 50 mm, 0 deg, and 0 deg, respectively, and J2 is gripped by 10N.

  The control elements of the hand control device 500 include a correction amount calculation unit 520, a command value generation unit 530, motor control units 541 to 545, and a motor driver 505, as in the case of FIG. A portion different from the first embodiment is a correction amount calculation unit 520. When the hand 300 grips the workpiece W1d by force control, the correction amount calculation unit 520 of the second embodiment acquires the correction amount of the finger whose position is to be controlled by calculation described later.

  The correction amount calculation unit 520 includes a correction coefficient selection unit 521 and a correction amount calculation unit 522 as in FIG. 4 of the first embodiment. The correction coefficient selection unit 521 is the same as that in the first embodiment. In the present embodiment, a portion different from the first embodiment is a correction amount calculation unit 522. The correction amount calculation unit 522 of the present embodiment includes the correction coefficient selected by the correction coefficient selection unit 521, the force command value of the grip command table 511 ′, the position command value, the stiffness coefficient of the workpiece W1d, and the force sensor 341. , 342, the correction amount of the finger whose position is to be controlled is calculated based on the current force value.

  Here, gripping position control when gripping the workpiece W1d of the hand control device 500 in the present embodiment will be described. As a precondition, the position correction is performed only in the gripping direction, and the workpiece W1d is positioned at the center position in the gripping direction of the workpiece.

  The procedure for performing the deflection correction by the hand control device 500 described above is the same as that in FIG. 8 of the first embodiment. However, the calculation in step S10 in FIG. 8 is different from that in the first embodiment. Hereinafter, the calculation in step S10 will be described with reference to FIG.

  In FIG. 13, first, the correction coefficient selection unit 521 selects a correction coefficient based on the correction coefficient table 512 (step S13). For example, when gripping the workpiece W1d, a35 and b35 (actually numerical values) are selected as the correction coefficients a3 and b3, respectively.

  Here, as shown in FIG. 12, when the work W1d is gripped by the fingers 3402 and 3403 of the hand 300, the involvement of the rigidity of the work is different from before and after each finger 3402 and 3403 is in contact with and grips the work W1d. Therefore, in the grip control considering the rigidity of the workpiece as in the present embodiment, it is determined whether or not the fingers 3402 and 3403 are in contact with the workpiece W1d and are gripped as in step S14. Then, before the gripping state is established, correction control (position control) using rigidity information is performed, and after the gripping state is established, correction control (position control) using the actual dimensions of the workpiece is performed without using the rigidity information. Do.

  Whether or not the workpiece W1d is before gripping in step S14 can be determined, for example, by monitoring the output value of the force sensor 342, that is, the change in gripping force, by the correction amount calculation unit 522. For example, an external force is not applied to the force sensor 342 before gripping, but the force sensor 342 starts to output a detection value corresponding to the external force when each finger 3402, 3403 comes into contact with the workpiece W1d. The determination as to whether or not the workpiece W1d is before being gripped can be detected through such an output change of the force sensor 342. However, whether or not the workpiece W1d is before gripping is determined by, for example, changes in the driving amounts (such as the driving current value of the motor 312) of the motors 311 to 315, which are the driving sources of the fingers, It may be detected via a change in the (relative) displacement amount of 3402, 3403.

  In step S14, when it is determined whether or not the workpiece W1d is before gripping via the output change of the force sensor 342, the following calculation is performed. For example, if the current detection value of the force sensor 342 is F2, step S14 is realized by making a determination as shown by the inequality of equation (5).

  However, ε in the above equation (5) corresponds to the minimum force resolution of the force sensor 342. If Expression 5 is satisfied, it is determined that it is before gripping, and the process proceeds to Step S15. If Expression 5 is not satisfied, it is determined that a gripping state is established, and the process proceeds to Step S16.

  When the condition of Expression (5) is satisfied in step S14 and the process proceeds to step S15, the hand 300 is in a state before gripping the workpiece W1d. In this case, the correction amount calculation unit 522 calculates the correction amount from the correction coefficients a3 and b3, the work stiffness coefficient of the gripping command table 511 ', and the force command value (Fref) that is the gripping force. In gripping the workpiece W1d in this case, the correction amount is calculated by the following equation (6), for example.

  Here, it is assumed that the correction amount of the finger 3403 (third finger) for position correction is ΔXref3, the gripping force generated on the finger 3402 (second finger) is Fref2, and the stiffness coefficient of the finger work is Kw. By the above equation (6), the hand control device 500 can perform position control including deflection correction in consideration of workpiece deflection Fref2 / (2Kw). Thereby, the hand 300 can be positioned at the center position in the gripping direction of the workpiece 1d immediately before gripping the workpiece W1d.

  On the other hand, if it is determined in step S14 that the condition of the expression (5) is not satisfied and it is after gripping and the process proceeds to step S16, the correction amount calculation unit 522 uses the correction coefficients a3 and b3 and the current output of the force sensor 342. The correction amount is calculated from the value (force value). In gripping the workpiece W1d in this case, for example, the correction amount is calculated by the following equation (7).

  Here, the correction amount of the finger 3403 (third finger) for position correction is ΔXref3, the output value of the force sensor 342 is F2, the current value of the position information of the finger 3402 (second finger) is X2, and the finger 3403 (third finger). ) Of the position information is X3. The current values (X2, X3) of the position information of the fingers 3402, 3403 can be calculated from the values of the encoders 332, 333, the reduction ratios of the speed reducers 322, 323, and the like.

  By the above equation (7), the actual deviation (X2-X3) / 2 of the width of the workpiece W1d can be estimated from the values of the encoders 332 and 333, and the gripping position where the workpiece should be gripped can be corrected. Thereby, even when there is a tolerance for the dimension of the workpiece W1d, the hand 300 can be positioned at the center position in the gripping direction of the workpiece while gripping the workpiece W1d.

  According to the present embodiment, for example, when gripping with a gripping force of 10 N, if the stiffness coefficient of the finger driving unit converted to the tip of the fingertip is 50 N / mm, the deflection amount of the fingertip is 10 N / (50 N / mm) = 0. 2 mm. Further, if the variation in the gripping direction of the workpiece W1d is ± 0.06 mm, the workpiece positioning accuracy is improved by about 0.23 mm (= 0.2 mm + 0.06 / 2) by using the deflection correction of this embodiment. Can do.

  As described above, according to the grip control of the present embodiment, it is possible to perform a correction calculation for correcting the grip position using the rigidity information of the workpiece. For this reason, even when the workpiece is deformed by the gripping force and the workpiece dimensions may vary, the deflection of the finger due to the gripping force can be corrected at the fingertip position of the hand, enabling highly accurate gripping position control. Thus, the workpiece positioning accuracy can be improved.

  Note that the control procedure in the deflection correction of the first and second embodiments described above is executed by the hand control device 500, for example. Accordingly, the recording medium storing the software program for realizing the above-described functions is supplied to the hand control device 500, and the CPU 501 of the hand control device 500 is configured to be read and executed. be able to. In this case, the program itself read from the recording medium realizes the functions of the above-described embodiments, and the program itself and the recording medium on which the program is recorded constitute the present invention. However, when the arm control device 400 is configured to also control the hand 300, the above-described grip control may be performed on the arm control device 400 side. In that case, the control program for performing the above-described grip control can be implemented as a part of the control program of the arm control device 400.

  In each of the above-described embodiments, the case where the computer-readable recording medium is the ROM 502 or the RAM 503 and the program is stored in the ROM 502 or the RAM 503 has been described. However, the present invention is limited to such a form. is not. The program for carrying out the present invention may be recorded on any recording medium as long as it is a computer-readable recording medium. For example, an HDD, an external storage device, a recording disk, or the like can be used as a recording medium for supplying the program.

  The present invention provides a process of supplying a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and reading or executing the program by one or more processors in the computer of the system or apparatus But it is feasible. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  DESCRIPTION OF SYMBOLS 100 ... Robot system, 200 ... Arm main body, 300 ... Hand, 3401-3402 ... Finger (1st finger-3rd finger), 311-315 ... Motor, 321-325 ... Reduction gear, 331-335 ... Encoder, 341, 342 ... Force sensor, 351 to 353 ... Link, 400 ... Arm controller, 500 ... Hand controller, 501 ... CPU, 502 ... ROM (recording medium), 503 ... RAM (recording medium), 504 ... General-purpose signal interface, 505 ... Motor driver, 511, 511 '... Grasping command table, 512 ... Correction coefficient table, 520 ... Correction amount calculation unit, 521 ... Correction coefficient selection unit, 522 ... Correction amount calculation unit, 530 ... Command value generation unit, 541-545 ... motor control unit, 546 ... position control unit, 547 ... force control unit, 548 ... control mode switching unit, 600 ... base J1, J2, J3, J4, J5 ... joint, S1 ... work rest, S2 ... work fixing table, W1, W2 ... workpiece.

Claims (17)

In a control method of a gripping device that controls a relative displacement amount of the plurality of gripping units according to a gripping force by which a plurality of gripping units grip a gripping target, and controls a gripping position of the gripping target,
A correction amount for calculating a correction amount for correcting the gripping position based on the gripping force and a correction coefficient for correcting the gripping position according to the gripping force corresponding to the relative postures of the plurality of gripping units. Calculation process;
A drive control step of controlling a drive source for relatively displacing the gripping portion based on the correction amount;
A method for controlling a gripping device including:   The control method of the gripping device according to claim 1, wherein the relative postures of the plurality of gripping units are changed to a specific relative posture, and the correction amount calculation step corresponds to the specific relative posture stored in the storage device. A method for controlling a gripping device, which reads a correction coefficient to be calculated and calculates a correction amount for correcting the gripping position based on the gripping force and the correction coefficient read from the storage device.   The control method of the gripping device according to claim 2, wherein the gripping device includes a turning mechanism for turning the gripping portion, and the relative postures of the plurality of gripping portions when gripping the gripping object are specified relative to each other. In the correction amount calculation step, the correction coefficient corresponding to the specific relative attitude stored in the storage device is read out, and based on the gripping force and the correction coefficient read out from the storage device. A method for controlling a gripping device that calculates a correction amount for correcting the gripping position.   4. The gripping device control method according to claim 1, wherein the gripping device is provided with a force sensor that detects the gripping force, and a part of the plurality of gripping portions is detected by the force sensor. 5. A method for controlling a gripping device that grips the gripping object by performing force control according to the gripping force that has been performed and controlling the position of another gripping portion.   5. The gripping device control method according to claim 1, wherein, in the correction amount calculation step, in addition to the gripping force and the correction coefficient, the gripping object is gripped by a plurality of gripping units. A gripping device control method for calculating the correction amount based on direction information of gripping force to be performed.   The gripping device control method according to claim 5, wherein the direction information of the gripping force includes information for distinguishing whether the gripping object grips the gripping object by an external shape or an internal shape. Control method.   The gripping apparatus control method according to any one of claims 1 to 6, wherein, in the correction amount calculation step, based on the gripping force and rigidity information of the gripping object in addition to the correction coefficient. A method of controlling a gripping device that calculates a correction amount.   The method of controlling a gripping device according to claim 7, wherein after detecting a gripping state in which the gripping object is gripped by a plurality of the gripping units via a change in the gripping force or the driving amount of the drive source, A correction amount calculation step, and a gripping device control method for executing the drive control step.   The control program for making the said holding | gripping apparatus perform each process of any one of Claim 1 to 8.   A computer-readable recording medium storing the control program according to claim 9. The relative displacement amounts of the plurality of gripping units are controlled according to the gripping force with which the plurality of gripping units grip the gripping object, and the gripping positions of the gripping objects gripped by the plurality of gripping units are controlled. In the gripping device,
A correction amount for correcting the gripping position is calculated based on the gripping force and a correction coefficient for correcting the gripping position according to the gripping force corresponding to the relative postures of the plurality of gripping units, and calculating A gripping device provided with a control device that controls a drive source for relatively displacing the gripping portion so that the gripping position becomes a target gripping position based on the correction amount. A plurality of gripping units for gripping a gripping object; a drive source for relatively displacing the plurality of gripping parts; a force sensor for detecting a gripping force by which the plurality of gripping parts grip the gripping object; and the force sensor In a gripping device comprising: a control device that controls a relative displacement amount of the plurality of gripping portions via the drive source according to the detected gripping force;
The control device includes the gripping force detected by the force sensor and a correction coefficient for correcting a gripping position of the gripping object according to the gripping force corresponding to a relative posture of the plurality of gripping units. A gripping device that calculates a correction amount for correcting the gripping position and controls the drive source based on the calculated correction amount.   The gripping device according to claim 12, wherein a posture control unit that changes a relative posture of the plurality of gripping units when gripping the gripping object, and a correction coefficient corresponding to each specific relative posture of the gripping unit. A storage device stored therein, and the control device changes a relative posture of the plurality of gripping units to a specific relative posture via the posture control unit, and a correction coefficient corresponding to the specific relative posture A gripping device that calculates a correction amount for correcting the gripping position based on the gripping force and the correction coefficient read from the storage device.   The gripping device according to claim 13, wherein the posture control unit includes a turning mechanism for turning the gripping unit, and the control device includes a plurality of gripping units via the turning mechanism of the posture control unit. The relative postures of the plurality of gripping portions when gripping the gripping object are changed to a specific relative posture, a correction coefficient corresponding to the specific relative posture is read from the storage device, the gripping force, and the A gripping device that calculates a correction amount for correcting the gripping position based on the correction coefficient read from the storage device.   The robot apparatus containing the robot arm provided with the holding | grip apparatus of any one of Claim 12 to 14.   The robot apparatus according to claim 15, wherein the control apparatus controls a position and orientation of the robot arm.   The manufacturing method of the components which hold | grips the target object with the said holding device with which the said robot arm of the robot apparatus of Claim 15 or 16 is assembled, and assemble components.

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