JP6541306B2 - Robot hand, robot apparatus, robot hand control method, article assembling method, control program, and storage medium - Google Patents

Description

The present invention, a robot hand provided with a hand body having a plurality of fingers, a robot apparatus provided with a robot hand, the control method of the robot hand, the assembly method of an article, the control program, and a storage medium.

  Industrial robots often use a parallel gripper type robot hand in which a plurality of finger portions for gripping a workpiece (object to be gripped) are linearly driven at the tip of an articulated arm. As this robot hand grips, conveys, or assembles workpieces of various shapes, rigidity, and weight, those having various gripping forces suitable for the work have been devised and commercialized.

  Such linear parallel drive of the finger portion of the robot hand is performed by using an AC motor or a stepping motor as a drive source, and various reduction mechanisms such as a reduction gear using a gear, a cam mechanism, and a link mechanism.

  Control of the gripping force for gripping a workpiece is generally performed by force control (current control) that controls a torque generated by a current supplied to a motor. In controlling the gripping force, a strain gauge was attached to the finger, or a pressure sensor was attached to the workpiece gripping portion at the tip of the finger, and the force acting on the workpiece was detected to improve the control accuracy of the gripping force. There is also one. We also propose a robot hand with a spring absorption mechanism at the tip of the finger to position the held workpiece minutely and to cushion the impact without dropping the held workpiece even if an accidental collision occurs. It is done.

  Patent Document 1 describes a parallel gripper type robot hand. In Patent Document 1, there is described one in which a finger attached to a linear guide is linearly and parallelly driven via a speed reduction mechanism attached to a shaft of a stepping motor. Patent Document 1 describes a method of controlling a gripping force by converting a torque (force) generated by a motor into a gripping force and controlling a current supplied to the motor.

  Patent Document 2 describes a robot hand in which a tip end portion of a finger is provided with a spring absorption mechanism. In Patent Document 2, a spring is attached to an intermediate joint of each finger so as to generate a rotational force around a rotation axis. When the attitude of each finger is controlled by the actuator, the joint is rotated according to the force received from the work by the force generated by the actuator and the spring force to generate the gripping force.

Unexamined-Japanese-Patent No. 5-212688 Unexamined-Japanese-Patent No. 6-143179

  In recent years, there has been an increasing demand for automatic assembly of small and complex products such as cameras and printers. In these electronic devices, metal or resin parts of various shapes are used, and most of these parts, in particular resin parts, are thin and rigid, and if gripped strongly, there is a possibility of breakage and proper gripping Force is required. In addition, even when the parts are assembled, even if they are slightly deformed, the parts can not be assembled, so that gripping with as weak a force as possible is also required. On the other hand, if reliable gripping is not performed, there is a possibility that parts will come off at the time of parts conveyance at high speed. Furthermore, recently, in order to improve production efficiency, assembly of several parts is required by one robot, and a wide range of high precision grip control is required.

  However, in the method disclosed in Patent Document 1, gripping force control is performed by load fluctuation due to Coulomb friction that changes between the moment of drive generated in the speed reduction mechanism and the transmission mechanism and after the drive, and viscous friction that changes with drive speed and environmental temperature. In particular, the controllability of the low gripping force is reduced. For example, when the maximum gripping force is 50 [N] and the control error is ± 5 [N], the current should be 1/10 to change the gripping force to 5 [N], but the control error is About 5 [N] occurs. This is because load fluctuation due to Coulomb friction or viscous friction is substantially constant regardless of the magnitude of the gripping force. Therefore, even if the control method described in Patent Document 1 is adopted, it is difficult to set a small gripping force.

  On the other hand, in Patent Document 2, a spring is attached to a joint in the middle of each finger so as to generate a rotational force around the rotation axis, and a small gripping force is generated by the force generated by the actuator and the spring force. Have been described. However, Patent Document 2 merely describes generating a small gripping force, and does not specifically describe how to control, so that a highly accurate gripping force can be realized. It was not.

Accordingly, the present invention is a robot hand, a robot apparatus provided with a robot hand, the control method of the robot hand to set the gripping force with high accuracy, and aims to provide an assembly method, control program, and storage medium of the article Do.

The robot hand according to the present invention transmits the driving force of the drive source in order to operate the plurality of finger portions , the drive source, and the plurality of finger portions in directions approaching or separating from each other to grip the work. A transmission mechanism, an angle detection unit that detects a rotation angle of the drive source, and a control unit that controls the drive source to operate the plurality of finger units, and at least one of the plurality of finger units The finger portion includes a first member coupled to the transmission mechanism, a second member coupled to the first member so as to be capable of swinging relative to the first member, and A regulating member which biases the second member, and contacts an elastic member which expands and contracts with the swing of the second member and the second member, thereby defining a swing range of the second member If has, the control unit may occur more the elastic member If gripping the workpiece by using an elastic force, while adjusting the expansion and contraction of the elastic member based on the detected value of the angle detection unit, the driving source so as to grip the said workpiece using said second member controls using the driving force by the drive source, when gripping the workpiece with a strong gripping force than the gripping force by the elastic force, while the second member is brought into contact with the regulating member, wherein drives the at least one finger portion, characterized that you control the driving source so as to grip the said workpiece using said second member.

  According to the present invention, the gripping force can be set with high accuracy.

It is an explanatory view showing a schematic structure of a robot apparatus concerning a 1st embodiment. It is a perspective view showing a robot hand concerning a 1st embodiment. It is an explanatory view showing opening and closing operation of a robot hand concerning a 1st embodiment. It is an explanatory view showing the state where the finger part of the robot hand concerning a 1st embodiment started grasping of the work. It is an explanatory view showing the state where the finger part of the robot hand concerning a 1st embodiment is grasping the work by the target grasping power. It is a perspective view of the robot hand concerning a 2nd embodiment. It is an explanatory view showing opening and closing operation of a robot hand concerning a 2nd embodiment. It is an explanatory view showing grasping operation of a robot hand concerning a 2nd embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First Embodiment
FIG. 1 is an explanatory view showing a schematic configuration of a robot apparatus according to a first embodiment of the present invention. As shown in FIG. 1, the robot apparatus 500 includes a robot hand 300 and a robot arm 400 which is a robot body. The robot hand 300 includes a hand body 100 and a control board (printed circuit board) 200. The control board 200 is built in the hand main body 100. The hand body 100 is attached to the end of the robot arm 400. The proximal end of the robot arm 400 is fixed on the work surface 601 of the work table 600.

  FIG. 2 is a perspective view showing a robot hand 300 according to the first embodiment of the present invention. The control substrate 200 of the robot hand 300 shown in FIG. 2 is illustrated outside the hand main body 100 for convenience of explanation. The hand main body 100 of the robot hand 300 detects the rotation angle (rotational position) of the base 101 formed in a plate shape, the rotation drive source 102 attached to one surface of the base 101, and the rotation drive source 102 And an encoder 103 which is an angle detection unit.

  The rotation drive source 102 has an AC motor 111 which is an electric motor, and a reduction gear 112 which is a reduction mechanism which decelerates and outputs rotation of an output shaft of the AC motor 111. The reduction gear 112 is, for example, a wave gear reduction gear. In the first embodiment, the reduction gear mechanism is configured of only the reduction gear 112, but the reduction gear mechanism includes the reduction gear and a transmission mechanism for transmitting the rotation of the output shaft of the AC motor to the reduction gear. It is also good. In addition, the rotational drive source 102 may have only the electric motor such as the AC motor 111 without the reduction mechanism. Further, although the case where the electric motor is an alternating current motor will be described, it may be a stepping motor or the like.

  The encoder 103 is a rotary encoder, and is, for example, an incremental type rotary encoder or an absolute type rotary encoder. The encoder 103 detects the rotation angle (rotational position) of the output shaft (rotor) of the AC motor 111 in the first embodiment, but the rotation angle (rotational position) of the output shaft 112A of the reduction gear 112 It may be detected.

  The hand body 100 has a plurality of (two in the first embodiment) finger portions 120 and 120. Among the plurality of finger portions 120, at least one finger portion, in the first embodiment, all the finger portions 120 respectively have a main finger 121 as a support member and a sub finger 122 as a gripping member.

  The hand main body 100 also has a conversion mechanism 130 for converting the rotational movement of the rotational drive source 102 (specifically, the output shaft of the reduction gear 112) into the opening and closing movement (linear movement) of the plurality of finger portions 120, 120. ing. The conversion mechanism 130 is driven by the rotational drive source 102 to move the plurality of finger portions 120, 120 in the direction of the arrow X1, which is the gripping direction (closing direction) for gripping the workpiece W, or in the opposite direction to the gripping direction It operates in the arrow X2 direction which is the direction (gripping and releasing direction). In the first embodiment, the conversion mechanism 130 is a rack and pinion mechanism.

  The base 101 is formed with a through hole through which the output shaft of the rotational drive source 102, that is, the output shaft 112A of the reduction gear 112 penetrates, and the tip of the output shaft 112A protrudes to the other surface of the base 101 ing.

  The conversion mechanism 130 has a pinion gear 131 attached to the output shaft 112A, and two rack gears 132 and 132 meshing with the pinion gear 131. A linear guide 133 is fixed to each rack gear 132. On the other surface of the base 101, two linear guide rails 134 and 134 arranged in parallel and spaced from each other are fixed. A linear guide 133 supported by a steel ball is disposed on each linear guide rail 134, and each linear guide 133 is linearly movable along each linear guide rail 134.

  The main finger 121 is connected to the rack gear 132 of the conversion mechanism 130, and moves with the rack gear 132 of the conversion mechanism 130 in the arrow X2 direction opposite to the arrow X1 direction which is the gripping direction.

  The secondary finger 122 is supported by the primary finger 121 so as to be movable relative to the primary finger 121 in the plane in which the primary finger 121 moves. In the first embodiment, the sub finger 122 is supported swingably in the forward and reverse directions (the directions of arrows X1 and X2) with respect to the main finger 121 in the moving plane of the main finger 121.

  As described above, since the gear portion of each rack gear 132 meshes with the gear portion of the pinion gear 131, the rotational driving force of the AC motor 111 via the reduction gear 112 is transmitted to each rack gear 132 as a linear driving force. Ru. Since each main gear 121 is attached to each rack gear 132, the rack gear 132 opens and closes in parallel by the linear operation of the rack gear 132. That is, the entire finger portion 120 is driven to open and close in the directions of arrows X1 and X2 which are close to or separated from each other.

  The main finger 121 has a closing side stopper 123 which is a first stopper which abuts on the sub finger 122 to define a moving range (swinging range) of the sub finger 122 and an open side stopper 124 which is a second stopper. . The position of the sub finger 122 is restricted by the open side stopper 124 and the close side stopper 123 in the arrow X2 direction which is the opening direction and the arrow X1 direction which is the closing direction.

  The finger portion 120 biases the sub finger 122, and expands and contracts along with the relative movement of the sub finger 122 with respect to the main finger 121, thereby generating an elastic force corresponding to the amount of expansion and contraction. A compression coil spring (elastic member) 140 for applying The compression coil spring 140 biases the sub finger 122 in the direction in which it abuts on the closing side stopper 123, that is, in the direction of the arrow X1 which is the closing direction.

  The configuration of the secondary finger 122 will be described in more detail. The sub finger 122 has a rod-like main body 122A which is a gripping member main body, and a gripping portion 122B provided at the tip of the main body 122A and formed to protrude in the arrow X1 direction which is a gripping direction with respect to the main body 122A. A central portion of the main body 122 </ b> A is supported by the main finger 121 so as to be pivotable about a pivot shaft 125.

  In addition, what is necessary is just to form the holding part of a sub finger so that it may protrude in the arrow X 2 direction, when hold | gripping the internal peripheral surface of cyclic | annular workpiece | work. In this case, the direction of arrow X2, which is the opening direction, is the gripping direction, and the direction of arrow X1, which is the reverse direction as the closing direction, is the gripping release direction.

  The compression coil spring 140 is disposed between the main finger 121 and the main body 122A, contacts between the central portion of the main body 122A and the proximal end, and compresses the main body 122A in the direction of arrow X2 by compression. The holding portion 122B is biased in the direction of the arrow X1 via

  Each main finger 121 has an abutment portion 126 formed on the side surfaces facing each other and protruding in the direction of the arrow X1. When the main finger 121 is in the fully closed state, the contact portions 126 abut each other.

  The control board 200 includes a control unit 201 configured of a semiconductor (control circuit) and a storage unit 202 configured of a semiconductor (memory circuit). The control unit 201 causes the AC motor 111 of the rotation drive source 102 to rotate and drive the gripping force of the workpiece W by the plurality of finger units 120 and 120 from the external controller (not shown). Control to force and grip force command value).

  Next, the operation of the robot hand 300 will be described. FIG. 3 is an explanatory view showing the opening and closing operation of the robot hand according to the first embodiment of the present invention, and FIG. 3 (a) shows a state in which the plurality of finger portions 120, 120 are maximally opened, FIG. 3 (b) Shows a state in which the plurality of finger portions 120, 120 are maximally closed.

  FIG. 3A shows the state at the start of operation of the hand main body 100 of the robot hand 300, each linear guide 133 is manually moved to the open side (outside), and the main finger 121 is maximally opened. In a state of The sub finger 122 is in contact with the closing stopper 123 by the elastic force (spring biasing) of the compression coil spring 140.

  Next, an origin detection operation is performed. Each linear guide 133 is operated in the direction of the arrow X1 which is the closing direction by the drive of the AC motor 111, and as shown in FIG. 3B, the main finger 121 set at the same position as the grip portion 122B of the sub finger 122. The contact portions 126 of the two are brought into contact with each other. Thus, each linear guide 133 is stopped.

  At this time, the control unit 201 stores (sets) an origin value (operation origin) in the storage unit 202 shown in FIG. 2 with the detection value (position) detected by the encoder 103 as the origin. After this, the state of FIG. 3A is returned to in preparation for the workpiece gripping operation.

  FIG. 4 is an explanatory view showing a state in which the finger portions 120, 120 start gripping the workpiece W. As shown in FIG. The work W is placed on the work surface 601 of the work table 600. In the storage unit 202 shown in FIG. 2, the position at which the gripping of the workpiece W shown in FIG. 4 starts is stored (set) in advance. The setting of the gripping start position will be specifically described. First, as shown in FIG. 3A, the finger portions 120 and 120 are moved to the maximum open state. Next, the finger portions 120 and 120 are moved from the origin value in the direction of the arrow X1 (gripping direction) until the finger portions 120 and 120 grip the workpiece W while preparing the workpiece W and visually checking by the worker.

  The control unit 201 acquires, from the detection result of the encoder 103, the amount of change from the origin value at the time (position) at which the finger units 120 and 120 start gripping the workpiece W. At this time, the gripping portion 122B is in contact with the workpiece W, but no gripping force for gripping the workpiece W can be regarded as 0 or 0, that is, no gripping force for gripping the workpiece W is generated. The control unit 201 stores (sets) the change amount in the storage unit 202 as a set amount. In addition, although the workpiece | work W was used in this description, you may use the reference | standard device of the workpiece | work W. FIG. That is, the workpiece W or the reference device used in setting the gripping position is a gripping jig.

  FIG. 5 is an explanatory view showing a state in which the finger portions 120, 120 grip the workpiece W with a target gripping force. FIG. 5 (a) shows the case where the target gripping force is a weak gripping force equal to or less than the threshold, and FIG. 5 (b) shows the case where the target gripping force is a strong gripping force exceeding the threshold.

  Here, the compression coil spring 140 generates an elastic force in proportion to the amount of expansion (compression). Therefore, a gripping force proportional to the elastic force of the compression coil spring 140 is generated in the sub finger 122 that expands and contracts the compression coil spring 140. That is, until the secondary finger 122 abuts on the open side stopper 124, a gripping force proportional to the amount of expansion (compression amount) of the compression coil spring 140 is generated. Therefore, the amount of change in the position of the main finger 121 when moving the main finger 121 in the direction of the arrow X1 from the start of gripping of the work W, that is, the amount of angular change in the rotation angle of the rotation drive source 102 (AC motor 111) A gripping force proportional to is generated.

  When the workpiece W is gripped with a weak gripping force, when the main finger 121 is moved in the direction of the arrow X1 from the state of FIG. 4 by driving of the AC motor 111 as shown in FIG. The work W is pressed in the direction.

  Thereby, the sub finger 122 swings in the direction of the arrow X2 about the swing shaft 125 against the elastic force (spring biasing) of the compression coil spring 140, and the arrow X1 proportional to the compression amount of the compression coil spring 140. A directional gripping force is generated on the gripping portion 122 B of the sub finger 122.

  In the first embodiment, the control unit 201 measures the amount of change in the detection value of the rotation angle detected by the encoder 103 based on the time when the workpiece W is gripped. Then, the control unit 201 rotates the AC motor 111 so as to change the angle change amount so that the target angle change amount necessary to set the holding force for holding the workpiece W to the target holding force. Thereby, the control unit 201 controls the gripping force of the sub finger 122 applied by the elastic force of the compression coil spring 140.

  Here, in the storage unit 202, the correspondence (table data or arithmetic expression) between the target gripping force and the target angle change amount is stored in advance. That is, since the gripping force and the angle change amount are in a proportional relationship, there is also a proportional relationship between the target gripping force and the target angle change amount, and the target gripping force can be converted into the target angle change amount. Therefore, in the first embodiment, the control unit 201 obtains a target angle change amount corresponding to the target gripping force based on the correspondence relationship stored in the storage unit 202. Then, the control unit 201 rotationally drives the AC motor 111 so that the amount of change in angle of the detection angle by the encoder 103 becomes the target amount of change in angle.

  As described above, the deflection amount with respect to the target gripping force determined from the spring constant (elastic coefficient) of the compression coil spring 140 is set as the movement amount from the contact position of the sub finger 122 of each work W to each linear guide 133 The workpiece W is gripped by the gripping force.

  The contact position (the amount of change from the origin value) of the grip portion 122B of the sub-finger 122 of the workpiece W can be calculated from the dimensions of the workpiece W known in advance and the amount of movement of the linear guide 133 by the encoder 103 as described above It is preset in the storage unit 202 as a set value. The control unit 201 determines the angle change amount from the origin value as the time when the workpiece W is gripped when the detected value of the rotation angle detected by the encoder 103 becomes a value obtained by changing the preset amount from the origin value in advance. Measure

  As described above, the setting range of the weak gripping force equal to or less than the threshold value is generated by bending the compression coil spring 140 from the position where the sub finger 122 abuts on the closing side stopper 123 until it abuts on the opening side stopper 124. It depends on the power of That is, when the target gripping force is equal to or less than the gripping force when the secondary finger 122 abuts against the opening side stopper 124 against the elastic force of the compression coil spring 140, the control unit 201 changes the angle change amount by the target angle. The AC motor 111 of the rotational drive source 102 is rotationally driven so as to obtain an amount.

  As described above, when the target gripping force is a weak gripping force equal to or less than the threshold, the elastic force of the compression coil spring 140 is changed by position control of the AC motor 111 using the encoder 103 to change the gripping force. Therefore, by setting the spring constant (elastic coefficient) of the compression coil spring 140, a weak gripping force can be realized.

  That is, the weak gripping force is set by the displacement of the compression coil spring 140 determined by the width of the portion held by the holding portion 122B in the workpiece W and the position of the main finger 121, that is, the amount of deflection of the compression coil spring 140. The positioning accuracy of the main finger 121 is about several microns to several tens of microns depending on the accuracy of the encoder 103 attached to the AC motor 111. On the other hand, the amount of deflection of the compression coil spring 140 or the spring force due to the deflection is free. It can be designed. Therefore, the setting of the weak gripping force can be coped with by replacing the matching spring with the gripping force and accuracy required for each robot, and it becomes possible to set a wide range of gripping force with high accuracy.

  Since the positioning control of the main finger 121 can perform the movement of the main finger 121 at a constant speed, it is not necessary to reduce the speed so as to set a weak gripping force by force control, preventing an increase in working time it can.

  Next, a gripping operation for gripping the workpiece W with a strong gripping force exceeding the threshold will be described. From the state shown in FIG. 4, the alternating current motor 111 is rotationally driven to cause each linear guide 133 to perform a closing operation by supplying a current that causes the alternating current motor 111 to generate a torque with a strong gripping force exceeding a threshold. Thus, after the grip portion 122B of the sub finger 122 abuts on the work W, the linear guide 133 continues the closing operation by the drive of the AC motor 111. Then, as shown in FIG. 5A, the sub finger 122 is pushed by the work W and swings around the swinging shaft 125 against the spring bias of the compression coil spring 140 and abuts against the open side stopper 124. Swing until it touches.

  Furthermore, since a current for generating a torque with a strong gripping force exceeding the threshold value flows in the AC motor 111, as shown in FIG. 5B, each linear guide 133 continues the closing operation. The sub finger 122 performs closing operation with the main finger 121 in a state of being in contact with the open side stopper 124, and the gripping portion 122B of the work W of the sub finger 122 has a strong gripping force corresponding to the torque generated in the AC motor 111. Occur.

  That is, when the target gripping force exceeds the gripping force (threshold value) when the secondary finger 122 abuts against the opening side stopper 124 against the elastic force of the compression coil spring 140, the control unit 201 causes the AC motor 111 to Perform current control of the supplied current. Specifically, the control unit 201 controls the torque (force) generated by the AC motor 111 with the current supplied to the AC motor 111 such that the gripping force for gripping the workpiece W becomes the target gripping force.

  For example, when the upper limit value of the setting of the target gripping force is 50 [N], the lower limit value of the adjustable range by current control is about 5 [N]. Therefore, the control unit 201 sets the threshold to 5 [N], and performs the above-described position control to realize a strong gripping force exceeding 5 [N] when realizing a weak gripping force of 5 [N] or less. If so, do the current control.

  In current control, after the secondary finger 122 abuts on the open side stopper 124, the swing position of the secondary finger 122 with respect to the main finger 121 changes even if the position of the main finger 121 (detection angle of the encoder 103) changes. do not do. Therefore, the amount of compression of the compression coil spring 140 does not change. Therefore, when the gripping force exceeds the threshold value, the gripping force applied by the compression coil spring 140 becomes constant, and the gripping force changes according to the change of the torque of the AC motor 111.

  That is, in the setting of the strong gripping force, the main finger 121 performs the gripping closing operation by supplying a current corresponding to the gripping force to the AC motor 111. As a result, the sub finger 122 abuts on the work W, and the compression coil spring 140 is flexed, and the sub finger 122 is turned to the open side stopper 124 and is cut off, and the main finger 121 and the sub finger 122 are integrated. In the state, a gripping force is generated.

  As described above, according to the first embodiment, the gripping force corresponding to the amount of expansion (compression) of the compression coil spring 140 can be set by position control based on the detection angle detected by the encoder 103, so high accuracy The gripping force can be set with. In particular, a gripping force that is weaker than a gripping force that can be set by current control of the current supplied to the AC motor 111 can be set with high accuracy.

  Further, by combining the position control and the current control, the gripping force can be set with high accuracy in a wide range from weak gripping force to strong gripping force.

Second Embodiment
Next, a robot hand according to a second embodiment of the present invention will be described. FIG. 6 is a perspective view of a robot hand according to a second embodiment of the present invention. In the robot hand 1300 shown in FIG. 6, the same components as those of the robot hand 300 described in the first embodiment are given the same reference numerals and the description thereof is omitted. The robot hand 1300 according to the second embodiment further includes a rotation detection switch 150, which is a movement detection unit, in addition to the components of the robot hand 300 according to the first embodiment. It is the same as that of the embodiment. Although the control board 200 is built in the hand main body 1100 of the robot hand 1300, it is illustrated outside the hand main body 1100 in FIG. 6 for convenience of explanation.

  Each finger portion 1120 of the hand main body 1100 has a rotation detection switch 150 which is a movement detection portion as shown in FIG. 6 in addition to the main finger 121, the sub finger 122, and the compression coil spring 140. The rotation detection switch 150 is disposed on each main finger 121. Each rotation detection switch 150 detects that the sub finger 122 grips the work W and starts compression and compression of the compression coil spring 140. That is, each rotation detection switch 150 detects whether the secondary finger 122 has moved (rocked) from the position where it abuts on the closing side stopper 123.

  In the first embodiment, the control unit 201 determines that the workpiece W is gripped when the detected value of the rotation angle detected by the encoder 103 becomes a value obtained by changing the preset amount from the origin value in advance. The amount of change was measured. In the second embodiment, the control unit 201 detects by the encoder 103 the time when the rotation detection switch 150 detects that the sub finger 122 is swung as the time when the work W is gripped, based on the time when the work W is gripped. Measure the amount of change in the detected rotation angle detection value. Thereby, it is possible to cope with the case where the shape of the workpiece W which is a gripping target changes.

  Next, the operation of the robot hand 1300 will be described. FIG. 7 is an explanatory view showing the opening and closing operation of the robot hand according to the second embodiment of the present invention, and FIG. 7 (a) shows a state in which the plurality of finger portions 1120 and 1120 are maximally opened, FIG. 7 (b) Shows a state in which the plurality of finger portions 1120 and 1120 are maximally closed.

  FIG. 7A shows a state at the start of operation of the hand main body 1100 of the robot hand 1300, each linear guide 133 is manually moved to the open side (outside), and the main finger 121 is maximally opened. In a state of The sub finger 122 is in contact with the closing stopper 123 by the elastic force (spring biasing) of the compression coil spring 140.

  Next, an origin detection operation is performed. Each linear guide 133 is operated in the direction of the arrow X1 which is the closing direction by driving the AC motor 111, and as shown in FIG. 7B, the main finger 121 set at the same position as the grip portion 122B of the sub finger 122. The contact portions 126 of the two are brought into contact with each other. Thus, each linear guide 133 is stopped.

  At this time, the control unit 201 stores (sets) an origin value (operation origin) in the storage unit 202 shown in FIG. 6 with the detection value (position) detected by the encoder 103 as the origin. After this, the state of FIG. 7A is returned to in preparation for the workpiece gripping operation.

  Next, a gripping operation for gripping the workpiece W with a weak gripping force equal to or less than the threshold will be described. FIG. 8 is an explanatory view showing a gripping operation of a robot hand according to a second embodiment of the present invention. FIG. 8A shows a state in which the finger portions 1120 and 1120 start gripping the workpiece W, and FIG. 8B shows a state in which the finger portions 1120 and 1120 grip the workpiece W with a weak gripping force less than the threshold value. .

  In FIG. 8A, each linear guide 133 is closed by driving the AC motor 111, and the gripping portion 122B of the sub finger 122 is in contact with the workpiece W. The force for gripping the workpiece W is It has not occurred.

  Furthermore, when each linear guide 133 continues the closing operation by the drive of the AC motor 111, the sub finger 122 is pushed by the work W as shown in FIG. 8 (b) and the elastic force of the compression coil spring 140 (spring biasing Swinging around the swinging shaft 125 against the

  At this time, the rotation detection switch 150 attached to the main finger 121 detects the swing of the sub finger 122 and turns on. Then, as in the first embodiment, the deflection amount for the target gripping force determined from the spring constant of the compression coil spring 140 is set as the movement amount from the contact position of the sub-finger 122 of the work W for each linear guide 133 The workpiece W is gripped by the gripping force.

  Thus, the contact position between the workpiece W and the grip portion 122B of the sub finger 122 can be detected at a position where the rotation detection switch 150 attached to the main finger 121 is turned on by the swing of the sub finger 122.

  That is, assuming that the time when the rotation detection switch 150 detects a swing when the workpiece W is gripped, the control unit 201 measures the amount of change in the detection value of the rotation angle detected by the encoder 103 based on this time. Do. When the target gripping force is equal to or less than the gripping force when the secondary finger 122 abuts against the opening side stopper 124 against the elastic force of the compression coil spring 140, the control unit 201 changes the angle variation to the target angle variation The AC motor 111 is rotationally driven so that

  The setting range of the weak gripping force equal to or less than the threshold is generated by bending the compression coil spring 140 from the position where the sub finger 122 is in contact with the closing side stopper 123 to the rotation operation to abut the opening side stopper 124. It depends on the force.

  The gripping operation for gripping with a strong gripping force exceeding the threshold value is the same as that of the first embodiment, and therefore the description thereof is omitted.

  As described above, according to the second embodiment, similarly to the first embodiment, the gripping force can be set with high accuracy in a wide range from weak gripping force to strong gripping force.

  Further, in the second embodiment, the rotation detection switch 150 detects that the secondary finger 122 starts to swing and is in contact with the workpiece W, thereby detecting the position at which the secondary finger 122 contacts the workpiece W. . As a result, it becomes possible to set a weak gripping force on the actual workpiece W to be gripped, and even if the dimensional accuracy of the workpiece W is low, or even if the position at which the workpiece W is placed deviates, high accuracy is achieved. You can set the gripping force. Furthermore, it is also possible to detect the dropout of the work due to some abnormal operation.

  The present invention is not limited to the embodiments described above, and many modifications can be made within the technical concept of the present invention.

  In the above embodiment, the case where the sub finger 122 swings (rotates in the normal and reverse directions) about the swing axis 125 with respect to the main finger 121 has been described, but the present invention is not limited thereto. It may be a linear movement with respect to

  Further, in the above embodiment, although the case where the elastic member is the compression coil spring 140 has been described, another spring such as a tension coil spring may be used, and not only the spring but also rubber may be used.

  Moreover, although the said embodiment demonstrated the case where the control board 200 was incorporated in the hand main body, you may arrange | position the exterior of a hand main body.

  Moreover, although the case where the finger part was two was demonstrated in the said embodiment, three or more may be sufficient.

DESCRIPTION OF SYMBOLS 100 ... Hand body, 102 ... Rotational drive source, 103 ... Encoder (angle detection part), 120 ... Finger part, 121 ... Main finger (support member), 122 ... Secondary finger (gripping member), 130 ... Conversion mechanism, 140 ... Compression coil spring (elastic member), 201: control unit, 300: robot hand, 400: robot arm (robot main body), 500: robot device

Claims (12)

And a plurality of fingers,
A driving source,
A transmission mechanism that transmits the driving force of the drive source to operate the plurality of finger portions in a direction toward or away from each other to grip a workpiece;
An angle detection unit that detects a rotation angle of the drive source;
A control unit that controls the drive source to operate the plurality of finger units;
At least one finger portion of the plurality of finger portions is
A first member coupled to the transmission mechanism;
A second member coupled to the first member so as to be pivotable relative to the first member;
An elastic member that biases the second member and that expands and contracts with the swing of the second member;
And a defining member that defines a swing range of the second member by being in contact with the second member,
The control unit
If gripping the workpiece by using an elastic force more generated in the elastic member, while adjusting the expansion and contraction of the elastic member based on the detected value of the angle detection unit, the work with the second member Control the drive source to grip,
When gripping the work with a gripping force stronger than the gripping force by the elastic force using the driving force by the driving source , the at least one finger is kept in contact with the second member while the second member is kept in contact with the defining member. part drives the robot hand, characterized that you control the driving source so as to grip the said workpiece using said second member. The control unit
When the detected value of the angle detection unit becomes a predetermined value, it is assumed that the work and the plurality of finger portions are in contact with each other,
The criteria said predetermined value, in Rukoto to change the rotation angle of the driving source, a grip force when gripping the workpiece by using an elastic force generated by the elastic member, the driving force by the drive source The robot hand according to claim 1, wherein the robot hand is used to control the gripping force when gripping the workpiece . The apparatus further comprises a rocking detection unit that detects whether the second member has rocked or not.
The control unit
When the swing detection unit detects the swing of the second member, it is assumed that the work and the plurality of finger portions are in contact, and the detection value of the angle detection unit at that time is the predetermined value. in Rukoto changing the rotation angle of the drive source based on the said predetermined value, and the gripping force when gripping the workpiece by using an elastic force generated by the elastic member, by using the driving force by the drive source The robot hand according to claim 2, which controls the gripping force when gripping the work . A storage unit that stores the expansion / contraction amount of the elastic member corresponding to the amount of change from the predetermined value , with the detection value of the angle detection unit when the work contacts the plurality of finger portions as the predetermined value And further
The control unit
By controlling the amount of expansion and contraction of the elastic member using the angle detection unit and the storage unit , the gripping force in the case of gripping the work is controlled using the elastic force generated by the elastic member ,
The gripping force in the case of gripping the work using the driving force by the drive source is determined based on the predetermined value while the second member is in contact with the defining member, the at least one finger portion The robot hand according to claim 2, wherein the robot hand is driven and controlled. The drive source is an electric motor,
The robot hand according to any one of claims 2 to 4, wherein the angle detection unit detects a rotation angle of an output shaft of the electric motor. The second member is
A body whose center is pivotally connected to the first member;
And a projecting portion provided on the main body and in contact with the defining member,
The robot hand according to any one of claims 1 to 5 , wherein the elastic member is provided between the first member and the projection. The robot hand according to any one of claims 1 to 6 , wherein the elastic member is a spring. A robot apparatus in which the robot hand according to any one of claims 1 to 7 is attached to a robot arm. A plurality of finger units, a drive source, an angle detection unit for detecting a rotation angle of the drive source, and a plurality of finger units are operated in a direction in which the plurality of finger units approach or separate from one another for, with handheld book having a transmission mechanism for transmitting driving force of the driving source,
At least one finger portion of the plurality of finger portions is
A first member coupled to the transmission mechanism;
A second member coupled to the first member so as to be pivotable relative to the first member;
An elastic member that biases the second member and that expands and contracts with the swing of the second member;
A control method of a robot hand comprising: a defining member that defines a swing range of the second member by contacting the second member;
If gripping the workpiece by using an elastic force more generated in the elastic member, while adjusting the expansion and contraction of the elastic member based on the detected value of the angle detection unit, the work with the second member and as you grip Engineering,
When gripping the work with a gripping force stronger than the gripping force by the elastic force using the driving force by the driving source , the at least one finger is kept in contact with the second member while the second member is kept in contact with the defining member. part drives the control method characterized by having a, and as engineering you grip the workpiece using the second member. A plurality of finger units, a drive source, an angle detection unit for detecting a rotation angle of the drive source, and a plurality of finger units are operated in a direction in which the plurality of finger units approach or separate from one another for, with handheld book having a transmission mechanism for transmitting driving force of the driving source,
At least one finger portion of the plurality of finger portions is
A first member coupled to the transmission mechanism;
A second member coupled to the first member so as to be pivotable relative to the first member;
An elastic member that biases the second member and that expands and contracts with the swing of the second member;
A method of assembling an article using a robot hand having: a defining member that defines a swing range of the second member by contacting the second member;
If gripping the workpiece by using an elastic force more generated in the elastic member, while adjusting the expansion and contraction of the elastic member based on the detected value of the angle detection unit, the work with the second member and as you grip Engineering,
When gripping the work with a gripping force stronger than the gripping force by the elastic force using the driving force by the driving source , the at least one finger is kept in contact with the second member while the second member is kept in contact with the defining member. part drives the, and as engineering you grip the workpiece using said second member,
Assembly method of an article, characterized in that said word click has a assembling step of assembling the target with the assembly, the. A control program capable of executing the control method or the method of assembling an article according to claim 9 or 10 . A computer readable storage medium capable of reading the control program according to claim 11 .

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