JP5492168B2 - Grip mechanism - Google Patents

Description

  Embodiments described herein relate generally to a gripping mechanism.

  The gripping mechanism is provided in gripping devices, robot end effectors, machine tools, industrial robots, service robots (hands), etc., in automatic production lines, and is used when lifting or transporting objects such as workpieces. It is a mechanism for gripping.

JP 2006-35329 A JP 2009-233790 A

  It is desired to provide a gripping mechanism that grips an object by a gripping force by an elastic damping element.

  According to the embodiment, a gripping mechanism for gripping an object by the first gripping portion and the second gripping portion is provided. Either one of the first gripping portion and the second gripping portion is connected to the fixing member, the base end member rotatably connected to the fixing member, the base end member, and an elastic damping element And a uniaxial linear movement mechanism that linearly moves the elastic damping element in the uniaxial direction. The gripping mechanism grips the object by receiving the force generated by the elastic damping element by the linear movement and the base end member turning.

Schematic of the overall configuration including a gripping mechanism and a control device according to the first embodiment Front view of gripping mechanism Block diagram of functional components of gripping mechanism The figure which shows the list of command information and the judgment part output of each operation mode Diagram showing the operation sequence of the gripping mechanism Diagram showing operation sequence of gripping mechanism The figure which shows the state which the holding mechanism hold | gripped the target object The flowchart which shows the operation | movement procedure which acquires the expansion-contraction amount data of the elastic damping element in a no-load state Flow chart showing operation procedure of contact detection Graph showing the change of sensor output value for the amount of expansion and contraction of elastic damping element Flow chart showing operation procedure of grip force estimation Flow chart showing operation procedure of gripping posture estimation Side view of the gripping mechanism according to the second embodiment The graph which shows transition of the sensor output value regarding the expansion-contraction amount of the elastic damping element which concerns on 2nd Embodiment

(First embodiment)
Embodiments of the present invention will be described below with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted. The present embodiment relates to a gripping mechanism for gripping an object and a control device for the gripping mechanism. It is assumed that the fixed state and mass of the grasped object are known.

  FIG. 1 is a schematic diagram of an overall configuration including a gripping mechanism and a control device according to the first embodiment, FIG. 2 is a front view of the gripping mechanism, and FIG. 3 is a block diagram of functional components of the gripping mechanism.

  As shown in FIG. 1, the first grip 112 has a fixed member 112a and three movable members, a base end member 112b, an intermediate member 112c, and a tip member 112d. The first grip 112 corresponds to one finger formed by these three movable members. The second grip 114 corresponds to another finger provided so as to face the first grip 112. An object is gripped by the first gripping part 112 and the second gripping part 114. For this purpose, the movable member and the mechanism for driving the movable member may be provided in both the first grip portion 112 and the second grip portion 114, or may be provided only in the first grip portion 112. FIG. 1 corresponds to a configuration in which both the first gripping portion 112 and the second gripping portion 114 are the same and have a movable gripping mechanism. The first grip 112 and the second grip 114 are motor driven by a motor drive instruction from the control device 120. In FIG. 1, only the sensor signal from the first gripping part 112 is shown to be supplied to the control device 120, but a similar signal is supplied from the second gripping part 114 to the control device 120. The Or it is good also as a structure which does not output a sensor signal from the 2nd holding | grip part 114. FIG. In this case, contact detection with the target object and grip force estimation cannot be performed for the second grip portion 114.

  In the case where only one of the two gripping portions disposed opposite to each other is a movable gripping mechanism, the other gripping portion does not necessarily have the shape of a finger as shown in FIG. For example, the shape may be a wall surface so that the object can be grasped together with the portion. In the following description, the first grip portion 112 and the second grip portion 114 are collectively referred to as “the grip portion 112”.

  The fixed member 112a and the base end member 112b are connected so as to be rotatable through a fixed hinge portion 112g. The proximal end member 112b and the intermediate member 112c are rotatably connected via the first hinge portion 112h. The intermediate member 112c and the tip member 112d are rotatably connected via the second hinge part 112i. The fixing member 112a has a fourth hinge portion 112k at a position other than the same axis as the fixed hinge portion 112g. The base end member 112b has a fifth hinge portion 112l at a position other than the same axis as the first hinge portion 112h at the end on the intermediate member 112c side. The intermediate member 112c has a sixth hinge portion 112m at a position other than the same axis as the first hinge portion 112h at the end portion on the base end member 112b side. The tip member 112d has a seventh hinge portion 112n at a position other than the same axis as the second hinge portion 112i at the end on the intermediate member 112c side.

  In addition, the grip portion 112 connects the fourth hinge portion 112k and the sixth hinge portion 112m so that the three movable members of the base end member 112b, the intermediate member 112c, and the tip end member 112d rotate in conjunction with each other. 1 link member 112e, and the 2nd link member 112f which connects the 5th hinge part 112l and the 7th hinge part 112n are provided.

  The grip 112 has a uniaxial linear movement mechanism 113. The uniaxial linear motion mechanism 113 includes a screw shaft 113 a connected to a motor (driving means) 203 and a lot 111. Note that the motor 203 is not shown in FIG. The lot 111 is a movable portion that moves straight when the screw shaft 113 a is rotated by the motor 203. The lot 111 has a third hinge portion 112j. The third hinge part 112j is connected to the first hinge part 112h via a passive linear link member 110 having an elastic damping element.

  The passive linear motion link member 110 has an elastic part that tends to return to the original state when a load is applied and contracted from a fully extended state in an unloaded state. As such a passive linear motion link member 110, a gas spring may be used. In the following description, the passive linear link member 110 is referred to as “gas spring 110”.

  In the first embodiment, the grip portion 112 arranged horizontally and the uniaxial linear movement mechanism 113 are arranged in parallel (horizontal arrangement). Specifically, the arrangement relationship is such that the longitudinal direction of the fixing member 112a of the grip portion 112 and the longitudinal direction of the screw shaft 113a of the uniaxial linear motion mechanism 113 are parallel to each other. In this case, when the change in expansion / contraction amount of the gas spring 110 with respect to the position of the lot 111 is shown in a graph, a quadratic curve having a vertex at the point closest to the fixed hinge portion 112g is obtained. This point will be described later with reference to FIG.

  As can be seen from FIG. 2, the base end member 112 b is composed of a pair of plates arranged to face each other. The lower end of each plate (the end on the fixing member side) is connected to the fixing member 112a via the fixing hinge portion 112g. The plate interval w1 of the base end member 112b is wider than the plate interval w2 of the fixed member 112a. Each plate upper end (end portion on the distal end member side) of the base end member 112b is connected to the intermediate member 112c via the first hinge portion 112h. The plate interval w1 of the base end member 112b is wider than the width w3 of the intermediate member 112c. One end of the gas spring 110 is pivotally supported by the first hinge portion 112h. The gas spring 110 rotates around the first hinge portion 112h when the lot 111 of the uniaxial linear motion mechanism 113 moves linearly. In order to prevent mechanical contact with the gas spring 110, the fixing member 112 a has a substantially “U” shape that is open.

  One end of the first link member 112e is rotatably connected to the intermediate member 112c, and the other end is rotatably connected to the fixing member 112a. One end of the second link member 112f is rotatably connected to the base end member 112b, and the other end is rotatably connected to the distal end member 112d. According to the first link member 112e and the second link member 112f, the pressing force from the gas spring 110 is transmitted to the intermediate member 112c and the tip member 112d.

  When the base end member 112b contacts the mechanical stopper 115 of the fixing member 112a, the movement of the base end member 112b is stopped. The mechanical stopper 115 is shown in FIGS. 5 and 6 described later.

  The lower end of the intermediate member 112c is connected to the base end member 112b via the first hinge portion 112h. Further, the intermediate member 112c has a rotatable connecting portion connected to the first link member 112e at a position other than the same axis as the first hinge portion 112h (sixth hinge portion 112m). The upper end of the intermediate member 112c is connected to the tip member 112d via the second hinge portion 112i.

  The tip member 112d has a U-shaped cross section that opens downward, is connected to the intermediate member 112c via the second hinge part 112i, and is positioned other than coaxial with the second hinge part 112i. Has a rotatable connecting portion connected to the second link member 112f (seventh hinge portion 112m).

  As shown in FIG. 3, an arm 201 driven by a driving device 202 is connected, a fixing member 112a is connected to the arm 201, and a gripping portion 112 is rotatably connected to the fixing member 112a. The single axis linear motion mechanism 113 is driven by a motor 203. The rotation amount of the motor 203 is read by the motor encoder 204 and sent to the motor drive servo control unit 104. The motor drive servo control unit 104 controls the motor 203 through the motor driver 205 in accordance with an instruction from the drive device 202. The uniaxial linear motion mechanism 113 is connected to the grip portion 112 via the gas spring 110. The expansion / contraction amount of the gas spring 110 that changes in accordance with the positional relationship between the uniaxial linear motion mechanism 113 and the grip portion 112 is detected by the expansion / contraction amount detection sensor 207. Further, the movement amount of the movable part (lot 111) when the uniaxial linear motion mechanism 113 is driven is detected by the movement amount detection sensor 206.

  Next, the control device 120 shown in FIG. 1 will be described.

  As shown in FIG. 1, the control device 120 is connected to the grip portion 112. The control device 120 performs contact detection by the grip unit 112, grip force estimation, and grip posture estimation. As illustrated in FIG. 3, the uniaxial linear motion mechanism 113 includes a movement amount detection sensor 206, and the gas spring 110 includes an expansion / contraction amount detection sensor 207. Sensor signals (for example, voltage values) detected by these sensors 206 and 207 are taken into the control device 120 via the signal processing circuit unit 105 such as an amplifier. As the movement amount detection sensor 206, for example, a potentiometer, a capacitance type sensor, a laser displacement meter, an encoder, or the like can be used. As the expansion / contraction amount detection sensor 207, for example, a potentiometer, a laser displacement meter, a pulse coder, or the like can be used.

  Hereinafter, a series of operations in which the control device 120 controls the gripping operation by the gripping unit 112 according to the work command 101 will be described.

  First, a work command 101 related to a series of operations of the gripping mechanism is input to the operation command generation unit 102. The work instruction 101 may be in the form of a program. The operation command 101 displayed on the panel may be input by the person to the control device 120 or may be instructed by voice. The input device for inputting the work command 101 may be integrated with the grip unit 112 and the control device 120, or may be capable of communicating with the grip unit 112 and the control device 120 by wire or wirelessly.

  The operation command generation unit 102 decomposes the input work command 101 into operation procedures necessary for each work process, and expands the operation procedure into an operation command level instruction sequence for the motor 203. The target command value generation unit 103 calculates each target trajectory and target value for the motor 203 in accordance with each generated operation command, and outputs a target command value related to driving of the single-axis linear motion mechanism 113. The motor drive servo control unit 104 controls the motor according to the target command value from the target command value generation unit 103 so that the motor performs an operation corresponding to the work.

The determination unit 106 detects contact of the grip portion 112 with the object based on sensor signals from the movement amount detection sensor 206 and the expansion / contraction amount detection sensor 207. Further, the determination unit 106 performs various determination processes such as estimating a gripping force when the gripping unit 112 is gripping an object and estimating a posture of gripping the object. Such determination processing by the determination unit 106 performs the arithmetic processing such as obtaining the difference variation of the amount of expansion and contraction data of the gas spring 110 at each position L _i of the lot 111 in the non-contact state.

The operation command generation unit 102 sends operation mode information corresponding to operation commands that are sequentially output and executed to the operation mode information unit 107 together with information on the execution work. The operation mode information unit 107, the reference value V _ba for various working output values from the expansion and contraction amount data of the position information L _i and the gas spring 110 of the instruction lot 111 defined each operation mode included in the contrast, A gripping force estimation function F _force and a gripping posture estimation function F _form are set. These reference values and the like are used for contact detection with an object, grip force estimation, and grip posture estimation.

  Therefore, when contact detection or gripping force estimation is performed by the determination unit 106, the motor drive servo control unit 104 sends a motor drive stop or control to the motor drive servo control unit 104 according to a countermeasure control method for the motor 203 according to the defined operation mode. A servo lock command is sent, or a return value command for correcting the target value is sent to the operation command generator 102 in some cases. As a result, it is possible to perform the corresponding control operation suitable for the current operation with respect to contact detection, grip force estimation, and grip posture estimation, and to perform drive control that ensures the reliability and certainty of the grip operation.

  An example of setting work in the operation mode information unit 107 will be described with reference to FIG.

FIG. 4 is a diagram showing a list of command information and determination unit outputs in each operation mode. This is an example of the definition / setting contents for each operation mode in the operation mode information unit 107. As shown in FIG. 4, as the types of operation modes,
Four operation modes are defined: (1) contact detection mode (2) gripping force estimation mode (3) gripping posture estimation mode (4) low power consumption gripping mode.

For each operation mode, as command information 108,
(1) In the case of the contact detection mode, the determination reference value V _ba for detecting the expansion / contraction amount change is arbitrarily designated.
(2) In the case of the gripping force estimation mode, use of the relational expression F _force with the generated force with respect to each expansion / contraction amount of the elastic damping element
(3) In the case of the gripping posture estimation mode, use of a geometric constraint relation F _form between links,
(4) In the low power consumption gripping mode, it is determined that the motor is stopped.

  In addition, the determination unit 106 sets the content of the determination unit output such as a drive stop / lock command to the motor drive servo control unit 104 or a return value command to the operation command generation unit 102 for each command information 108 of each operation mode. Is done. As shown in FIG. 4, depending on the operation mode, different processes are defined according to each operation mode, such as stopping the driving of the motor 203 or maintaining the servo lock to maintain the posture holding state.

  Next, the operation of the gripping mechanism according to the first embodiment will be described with reference to operation outline diagrams shown in FIGS. 5 to 7 and flowcharts of respective operation modes shown in FIGS. 8 to 12.

  First, the operation of the grip portion 112 will be described with reference to FIGS. In the present embodiment, the lot 111 of the uniaxial linear motion mechanism 113 is driven by the motor 203. In FIG. 5, the lot 111 moves straight as the screw shaft 113 a is rotated by the motor 203. The advance / retreat amount of the lot 111 can be adjusted by the rotation amount of the screw shaft 113a. While the lot 111 moves from one end of the screw shaft 113a to the other end, when the gas spring 110 passes the position of the fixed hinge portion 112g which is a passive rotation fulcrum, passive rotation due to the reaction force of the gas spring 110 is performed. The direction of the rotational force around the fulcrum is switched, and accordingly, the three movable members of the base end member 112b, the intermediate member 112c, and the front end member 112d are rotated in conjunction with each other, and a bending operation that is an opening / closing operation of the finger is performed. FIG. 6 shows the movement of the three movable members, that is, the base end member 112b, the intermediate member 112c, and the front end member 112d. FIG. 7A shows a state where the grip portion 112 is bent without gripping the object, and FIG. 7B shows a state where the grip portion 112 grips the grip target. ing. The amount of expansion / contraction of the gas spring 110 differs between the state of FIG. 7A and the state of FIG.

The operation in the contact detection mode (1) will be described with reference to FIGS. The operation shown in FIG. 8 obtains data V _th (L _i ) of the amount of expansion and contraction of the elastic damping element at each position L _i of the lot 111 in the non-contact state for use in comparison data at the time of contact detection. It is. A motor drive instruction is output from the motor drive servo control unit 104 (step S1). Gripper 112 which has received the motor driving command from the motor drive servo control section 104, one-axis linear motion mechanism 113 drives the, the deformation amount of the elastic damping element at each position L _i of the lot 111 in a non-contact state Data V _th (L _i ) is acquired and stored (step S2). After data acquisition, a motor drive stop command is output from the motor drive servo control unit 104 (step S3).

Next, the contact detection operation will be described with reference to FIGS. 9 and 10. Receiving the movement instruction to the gripping object from the motor drive servo control unit 104, the driving device 202 drives the arm 201 and moves the gripping part 112 to the position of the object (step S11). At the end of step S <b> 11, the displacement of the gripping portion 112 has not started, and the objects are placed in the operating range of the gripping mechanism and are not in contact with each other. Next, the data V _th (L _i ) of the expansion / contraction amount of the elastic damping element at each position L _i of the lot 111 in the non-contact state acquired according to the flowchart of FIG. 8 is read (step S12). The reference value information (threshold value) _Vba determined based on input information from a person or a program is read from the operation mode information unit 107 as command information 108 (step S13). Next, the motor drive servo control unit 104 outputs a motor drive instruction for gripping the object (step S14). Accompanying the driving of the uniaxial linear motion mechanism 113, data V _exp (L _i ) of the amount of expansion / contraction of the elastic damping element at each position L _i of the lot 111 is acquired (step S15). During the gripping operation, the determination unit 106 of the grip control unit 109, the lot 111 in the gripping operation state deformation amount of data _V th _{(L i)} of the elastic damping element at each position _{L i} of the lot 111 in a non-contact state The difference amount from the expansion / contraction amount data V _exp (L _i ) of the elastic damping element at each position L _i is compared with the determination reference value V _ba (step S16). After the contact is detected, the driving of the motor is stopped or the servo lock operation is performed (step S17).
FIG. 10 shows accurate and simple contact with the target object using the output value data V _th (L _i ) and V _exp (L _i ) of the expansion / contraction amount of the elastic damping element at each position L _i of the lot 111. It is a figure explaining the detection method for detecting.

Determination unit 106, expansion amount detection sensor 207 takes in the output value at the sampling number of milliseconds from the expansion and contraction amount of data V _th of the elastic damping element at each position L _i of the lot 111 in a non-contact state _{(L i)} The difference change amount D is obtained, and when the difference change amount D satisfies a predetermined condition (for example, a difference change amount equal to or greater than the determination reference value _Vba ), it is determined that contact is detected. Specifically, the object contact detection is performed based on the detection of the deviation amount from the change value of the quadratic curve in the non-contact state. This is because each joint portion is bent in conjunction with the grip portion 112, so that each joint angle of the finger is fixed by contacting with the object, and the amount of expansion and contraction of the gas spring 110 with the movement of the one-axis linear motion mechanism 113 Uses a phenomenon that behaves differently from the non-contact state.

The operation in the gripping force estimation mode (2) will be described with reference to FIG. As shown in FIG. 11, a motor drive instruction is output from the motor drive servo control unit 104 (step S21). Gripper 112 which has received the motor driving command from the motor drive servo control section 104, one-axis data V of the expansion amount of the elastic damping element at each position L _i of the linear motion mechanism 113 Lot 111 in the drive to driven state _exp (L _i ) is acquired as needed (step S22). Since each joint part of the grip part 112 bends in conjunction with each other, the bending posture of the grip part 112 with respect to the position of the lot 111 of the uniaxial linear motion mechanism 113 is geometrically unique together with the expansion and contraction amount of the gas spring 110. Determined. The gripping force is estimated from the uniquely determined gripping posture and the measured value of the expansion / contraction amount of the gas spring 110 (step S23). Finally, the motor drive is stopped or a servo lock operation is performed (step S24).
The operation when the operation mode is (3) the gripping posture estimation mode will be described with reference to FIG. As shown in FIG. 12, a motor drive instruction is output from the motor drive servo control unit 104 (step S31). Gripper 112 which has received the motor driving command from the motor drive servo control section 104, one-axis linear motion mechanism 113 drives the expansion and contraction amount of data of the elastic damping element at each position L _i of the lot 111 in the driven state V _exp (L _i ) is acquired as needed (step S32). Since each joint part of the grip part 112 bends in conjunction with each other, the bending posture of the grip part 112 with respect to an arbitrary position of the lot 111 of the uniaxial linear motion mechanism 113 is geometrically combined with the expansion / contraction amount of the gas spring 110. It can be estimated using the constraint relationship. (Step S33). Finally, the motor drive is stopped or the servo lock operation is performed (step S34).

  The operation when the operation mode is (4) the low power consumption gripping mode will be described. This is a mode that uses the principle that the gripping state is maintained because the uniaxial linear motion mechanism 113 does not reversely rotate even if the power supplied to the motor 203 is cut off in the mechanism of this embodiment. In this mode, driving of the motor 203 is stopped.

  The gripping mechanism of the present embodiment described above realizes the opening / closing (bending) operation of the gripping portion 112 using the movement of the uniaxial linear motion mechanism 113 and the switching of the reaction force direction of the gas spring 110. By using the uniaxial linear motion mechanism 113, it is possible to select the gas spring 110 having a large repulsive force (a large output capacity) compared to the motor output capacity, thereby realizing a high gripping force. It is. Furthermore, gripping according to the outer shape of the gripping object can be realized by the repulsive force and compliance of the gas spring 110. Since the reaction force from the gripping object is not directly transmitted to the motor 203, it is possible to prevent an excessive load from being applied to the motor 203 (overload prevention function). Further, since the object to be grasped is grasped by the repulsive force of the gas spring 110, the grasping can be maintained even if the power supply to the motor 203 is cut off, and in such an operation, power saving can be realized. . The opening / closing angle of the grip portion 112 can be defined in advance depending on how the link mechanism between the members is arranged. Further, since the finger shape is uniquely determined from the position of the lot 111 and the amount of expansion and contraction of the gas spring 110, the approximate outer shape of the grasped object can be estimated by using a plurality of grasping portions 112 of the present embodiment. This has the advantage that the object shape can be predicted even in an environment where visual information is limited.

  In the present embodiment, when the shape of the gripping object changes (such as a phenomenon that the empty box is crushed), the bending angle of the gripping portion 112 changes. Accordingly, the expansion / contraction amount of the gas spring 110 with respect to the position of the lot 111 changes, so that it is possible to cope with the deformation of the object. Since the gripping force is directly measured according to the gripping position, the object can be gripped with an appropriate gripping force even in the case of inhomogeneity with different elasticity depending on the gripping position. In addition, by providing an elastic damping element by the gas spring 110, the vibrational movement of the grip portion 112 caused by disturbance due to deformation of the outer shape of the gripping object is suppressed, and gripping following the deformation of the object is suppressed. This is possible and the controllability of the grip control is improved.

  As the damping element of the gas spring 110, an oil damper, a viscous damper, a damping rubber, or the like can be used. As the elastic element of the gas spring 110, various elastic bodies such as a coil spring, a leaf spring, rubber, urethane, and silicon can be used.

  In the present embodiment, the object to be grasped is a very soft object (for example, a soft towel or a paper balloon), an object that deforms irreversibly (a bag containing liquid or powder), or a very fragile object (thin glass product). Etc.), and can be applied to a wide range of objects.

  In the above description, it is assumed that a relatively small object that can be held in the hand is held with multiple fingers, but a large object that is difficult to hold with one hand is sandwiched between multiple arms. The present invention can also be suitably applied when gripping with a.

  Although the first embodiment has been described above, the embodiment is not limited to the above-described embodiment, and can be changed in a timely manner without departing from the technical idea thereof.

(Second Embodiment)
FIG. 13 is a side view of the gripping mechanism according to the second embodiment. The gripping mechanism according to the second embodiment has a fixing member 112a so that the expansion / contraction amount of the gas spring 110 having the elastic damping element changes linearly as the lot 111 of the uniaxial linear movement mechanism 113 moves linearly. Is different from the first embodiment in that the uniaxial linear motion mechanism 113 is inclined at an arbitrary angle θ _f from the plane p parallel to the first embodiment (inclined arrangement).

In the second embodiment as described above, the data V _th (L _i ) of the expansion / contraction amount of the elastic damping element at each position L _i of the lot 111 is the output change of the quadratic curve as shown in FIG. Instead, a linear output change as shown in FIG. 14 can be obtained. Therefore, the position of the lot 111 can be uniquely determined from the value of the arbitrary expansion / contraction amount sensor output value, and there is an advantage that the movement amount detection sensor 206 is not required for linear movement on one axis.

  In the above-described embodiment, the configuration using the electric motor 203 as the driving unit has been described as an example. However, the driving unit is not limited to this, and an air cylinder, a hydraulic cylinder, or the like is used. Is also possible. However, if it is desired to arbitrarily change the bending posture of the grip portion 112, it is necessary to provide an actuator that can adjust the amount of advancement / retraction of the lot 111 of the uniaxial linear motion mechanism 113.

  FIG. 3 shows a configuration including the movement amount detection sensor 206 and the motor encoder 204, but only one of them can be used to obtain the advance / retreat amount information of the single-axis linear motion mechanism 113.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 101 ... Work command 102 ... Operation command generation part 103 ... Target command value generation part 104 ... Motor drive servo control part 105 ... Signal processing circuit part 106 ... Determination part 107 ... Operation mode information part 108 ... Command information 109 ... Grasping control part 110 ... Gas spring (passive linear link member with elastic damping element)
111... Lot (movable part of single axis linear motion mechanism)
112 ... 1st holding part 112a ... Fixed member 112b ... Base end member 112c ... Intermediate member 112d ... End member 112e ... 1st link member 112f ... 2nd link member 112g ... Fixed hinge part 112h ... 1st hinge part 112i ... 1st 2 hinge part 112j ... 3rd hinge part 112k ... 4th hinge part 112l ... 5th hinge part 112m ... 6th hinge part 112n ... 7th hinge part 113 ... 1 axis linear motion mechanism 114 ... 2nd holding part 115 ... mechanism Stopper 120 ... Control device 201 ... Arm 202 ... Drive device 203 ... Motor 204 ... Motor encoder 205 ... Motor driver 206 ... Movement amount detection sensor 207 ... Expansion / contraction amount detection sensor

Claims (5)

A gripping mechanism for gripping an object by a first gripping portion and a second gripping portion;
One of the first gripping part and the second gripping part is
A fixing member;
A proximal member rotatably connected to the fixed member;
A uniaxial linear movement mechanism fixed to the fixing member;
A lot that moves linearly along the one-axis linear motion mechanism;
A passive linear link member that expands and contracts by an elastic damping element,
One end of the passive linear link member and the base end member are rotatably connected,
The other end of the passive linear link member and the lot are rotatably connected,
The one-axis linear motion mechanism is
The base end member is rotated by the force generated by the elastic damping element, and the passive linear link member passes through the connection point of the fixed member and the base end member as the lot moves linearly. The gripping mechanism is arranged so that it is possible . An expansion / contraction amount detection sensor for detecting an expansion / contraction amount of the elastic damping element and outputting a sensor signal;
A database that stores data indicating changes in the sensor signal when the one-axis linear motion mechanism is driven when an object is not gripped;
A gripping force for gripping the object by detecting contact with the object based on a comparison between the change of the sensor signal and the data when the uniaxial linear motion mechanism is driven when gripping the object. A control unit for estimating
The gripping mechanism according to claim 1, further comprising: An intermediate member rotatably connected to the base end member;
A tip member rotatably connected to the intermediate member;
A first link member that connects the fixing member and the intermediate member and rotates the intermediate member by expansion and contraction of the passive linear link member;
A second link member that connects the base end member and the tip end member, and rotates the tip end member by turning the intermediate member;
The gripping mechanism according to claim 1 or 2, further comprising:   The gripping mechanism according to claim 2, wherein an attachment angle of the one-axis linear motion mechanism with respect to the fixing member is an angle at which the sensor signal output from the expansion / contraction amount detection sensor is linear with respect to the position of the lot. . The gripping mechanism is
A first state in which the elastic damping element receives a force repelling and extending from the base end member and the base end member rotates in a first direction to open;
A second state in which the elastic damping element receives a force repelling and extending from the base end member, and the base end member rotates in a second direction to be closed;
Can take
The lot is moved linearly along the first direction of the one-axis linear motion mechanism, and the connection point is passed through the passive linear motion link member, thereby shifting from the first state to the second state. The lot is linearly moved along a second direction opposite to the first direction of the one-axis linear motion mechanism, and the connection point is passed through the passive linear motion link member. The gripping mechanism according to claim 1, wherein the gripping mechanism shifts from the state 2 to the first state .

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