JP2018089752A - Gripping device, robot, control method of robot, and manufacturing method of article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve drive accuracy of a revolvable gripping part of a gripping device and facilitate adaption to various grip objects, so that grip accuracy of the gripping device is improved.SOLUTION: A grip object is gripped or released from gripping by relatively displacing plural fingers (110, 120 and 130) of a hand 100 in a closing direction or an opening direction relative to each other. The hand 100 comprises pivots O2 and O3 that cause the fingers 120 and 130 to revolve relative to a stem 140 in order to change a displacement direction of the fingers 120 and 130. A transmission device 149 is disposed for distributing drive power of a motor 141 to the plural pivots O2 and O3. The drive power distributed by the transmission device 149 is transmitted to each of the pivots via wave gear reducers 145A and 145B that are arranged respectively between the transmission device 149 and the pivots O2 and O3 in order to transmit the drive power to the pivots.SELECTED DRAWING: Figure 4

Description

  The present invention uses a gripping device for gripping or releasing a gripping object by relatively displacing a plurality of gripping portions supported by a base, a robot using the gripping device, a control method for the robot, and the robot The present invention relates to a method for manufacturing an article.

  Conventionally, as a gripping device, for example, a robot hand or gripper that is attached to the tip of a device for transporting or assembling an article, for example, a robot arm device using an articulated arm, grips an object, transports and assembles, etc. Are known. This type of gripping device includes a plurality of gripping portions called gripping nails and gripping fingers on the base portion, and grips or releases the gripping symmetry object by relatively displacing them on the base portion. As a drive source for relatively displacing a plurality of gripping units, a rotary drive source is mainly used for an electric actuator such as a stepping motor or a servo motor. The output of the rotational drive source is converted into a linear motion via a power transmission mechanism such as a rack gear, a cam, or a ball screw, and the plurality of gripping portions are relatively displaced. At least 2 to 3 or more gripping portions are arranged on the base portion, and the plurality of gripping portions are relatively displaced so as to open and close each other.

  However, in this type of gripping device, there are cases where the applicable range is limited, for example, the gripping claw is designed in accordance with the shape of the part to be gripped when carrying or assembling, the rigidity of the part, or the like. For this reason, it may be necessary to newly design and manufacture the gripping device. A configuration is also known in which a plurality of gripping devices having different specifications are prepared, and the gripping devices to be mounted on the robot arm are exchanged according to work. In such a configuration, there is a possibility that the operation efficiency of the article production line is lowered by exchanging the gripping device.

  In view of this, there has been proposed a robot hand in which the gripping part is swung on the base so that the relative displacement direction of the gripping part can be adjusted so that it can be adapted to the shape and size of the object to be gripped (for example, the following patent document) 1). In Patent Document 1, a robot hand has three finger portions as a gripping portion, and includes a turning mechanism that turns two of the three finger portions. In this turning mechanism, a transmission device having a gear train that distributes one motor output to the turning shafts of two turnable fingers is used.

Japanese Patent No. 5929215

  In general, in robot hands, for the purpose of reducing the size and weight, it is common to decelerate a high-revolution specification small motor with a transmission with a high reduction ratio and use a drive system with low rotation speed and high torque. The transmission system of the turning mechanism of Document 1 is similarly configured. In the transmission system of the turning mechanism of Patent Document 1, a gear train in which many worm gears, worm wheels, flat gears, and the like are combined is used.

  In a gear train having a multistage structure such as that disclosed in Patent Document 1, backlash occurs due to meshing of each gear and wheel, which may cause a large driving error. For this reason, a large angular error occurs in the pivot axes of the two fingers that are driven synchronously, the control accuracy in the direction of relative displacement of the plurality of fingers decreases, and the positioning of the fingers of the robot hand and the object to be grasped is reduced. It can be difficult.

  In view of the above-described problems, an object of the present invention is to improve the driving accuracy of a rotatable gripping unit of a gripping device, easily handle various gripping objects, and improve the gripping accuracy of the gripping device. There is.

  In order to solve the problem, the gripping device of the present invention is a gripping device that grips or releases a gripping object by relatively displacing a plurality of gripping portions supported by a base in a closing direction or an opening direction. The gripping portion is pivoted with respect to the base, and is disposed between a pivot shaft that changes the direction of relative displacement of the gripping portion, a rotational drive source, the pivot shaft, and the rotational drive source, A configuration provided with a turning mechanism including a wave gear transmission that changes the output of the rotational drive source and transmits the output to the turning shaft is adopted.

  According to the above configuration, it is possible to improve the driving accuracy of the gripping portion that can be turned by the gripping device, easily handle various gripping objects, and improve the gripping accuracy of the gripping device.

It is explanatory drawing which showed schematic structure of the robot system which can apply this invention. It is the perspective view which showed an example of the structure of the robot hand which implemented this invention. FIG. 3 is a top view of the robot hand of FIG. 2. It is the perspective view which showed the turning mechanism of the robot hand of FIG. It is explanatory drawing which showed the transmission device which distributes a driving force to the turning axis of the robot hand of FIG. It is sectional drawing which showed the structure of the turning mechanism of the robot hand of FIG. It is explanatory drawing which showed the example of grip control of the robot hand of FIG. (A)-(E) is explanatory drawing which showed the example of different holding | grip control of the robot hand of FIG. It is the flowchart figure which showed the example of grip control in the case of assembling articles | goods in the robot system of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. The embodiment described below is merely an example, and for example, a detailed configuration can be appropriately changed by those skilled in the art without departing from the spirit 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]
<Robot system>
The robot system 300 of this embodiment includes an arm main body 200, a hand 100, 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 workpiece W1 and the workpiece W2 with the robot system 300, an industrial product or an article such as a part 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 100, 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 100 that is a gripping device is attached to the tip of the arm main body 200 as an end effector. The A gripping or gripping release operation is performed on the workpiece W1 via the hand 100. 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 body 200 with respect to a target position / posture of the arm tip, which is a movement destination of the hand 100 used in assembly, 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 controls the hand 100 via command transmission to the hand control device 500 or the like.

  The hand control device 500 transmits a grip command or a grip release command to the hand 100 in response to a command from the arm control device 400. Further, the hand 100 includes a turning mechanism described later in order to change a gripping mode of a finger (finger) as a gripping unit, and controls the turning mechanism in accordance with a command from the arm control device 400. The grip command, the grip release command, or the control command for the turning mechanism is expressed by, for example, a number, that is, data in numerical expression.

  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.

  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 later-described control program for controlling the hand 100. A variable or constant area related to control described later can be arranged in a storage area of the RAM 503, for example. However, as for the constant area, those that can be made into ROM depending on the mounting specifications of the apparatus may be arranged in the storage area of the ROM 502. 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 motor described later for controlling the opening / closing (relative displacement) and turning of each finger of the hand 100 described later. .

  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 100 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.

<Configuration of robot hand>
FIG. 2 shows a configuration of a robot hand (hereinafter sometimes simply referred to as “hand”) of the present embodiment. As shown in the figure, the hand 100 of this embodiment includes three fingers 110, 120, and 130 as a grip portion on a base portion 140. Each of these fingers includes a motor 111, 121, 131 for moving the fingertips 114, 124, 134 forward or backward.

  The output shafts of the motors 111, 121, 131 are provided with gears (not shown), and power is transmitted to the input shafts of the reduction devices (not shown) provided on the support portions 112, 122, 132 provided on the fingers. The This reduction gear can be constituted by a wave gear reducer (145A and 145B described later) having a small number of gear stages and therefore a relatively small backlash. The outputs of these wave gear reducers are preferably coupled directly to links 113B, 123B, and 133B as will be described later. However, it may be transmitted through a backlash reduction mechanism configured by a method of dividing the gear into two and shifting the phase or using a conical gear. Moreover, the structure which transmits the output of the deceleration device which decelerates the output of motor 111, 121, 131 for opening and closing a fingertip to link 113A, 123A, 133A side instead of link 113B, 123B, 133B may be sufficient.

  The output shaft of this reduction gear transmits the reduced driving force to, for example, the links 113B, 123B, and 133B of each finger. The links 113A, 123A, and 133A are rotatably supported by the support portions 112, 122, and 132 through the rotation shaft at the lower end portion in the drawing. The fingertips 114, 124, and 134 are rotatably supported via the rotation shafts at the other ends of the links 113A, 123A, and 133A. In this example, the fingertips 114, 124, and 134 have a substantially L-shaped shape as a whole, and the upper ends of the links 113B, 123B, and 133B are rotatable at the other end of the lower L-shaped arm portion in the drawing. Are combined.

  Accordingly, the links 113A, 123A, and 133A together with the links 113B, 123B, and 133B constitute a four-node parallel drive link that operates while maintaining a parallel posture. The fingertips 114, 124, and 134 of each finger are linearly kept in a substantially upright posture with respect to the base 140 as shown in the figure by the driving force of the motors 111, 121, and 131 through this drive link. Can be relatively displaced so as to be close to or away from each other. Thereby, the fingertips 114, 124, and 134 of the fingers 110, 120, and 130 can be closed or relatively displaced in the opening direction, and the object to be grasped can be grasped or released.

  Furthermore, in the hand 100 of the present embodiment, the support parts 122 and 132 of the second and third fingers 120 and 130 are turned around the turning axes O2 and O3 by the base part 140, and the object to be grasped together with the first finger 110 is obtained. The posture at the time of gripping can be changed. Hereinafter, a configuration example of the second and third fingers 120 and 130 will be described with reference to FIGS.

  FIG. 3 shows the hand of FIG. 2 from above. As shown in FIG. 3, in the hand 100 of the present invention, three fingers 110, 120, and 130 are attached to the base portion 140 via support portions 112, 122, and 132. In the present embodiment, the first finger 110 among the plurality (three) of fingers is not provided with a turning axis like the second and third fingers 120 and 130, and the opening / closing drive direction of the finger 110 is not provided. Is only in the vertical (vertical) direction of FIG.

  On the other hand, on the base portion 140, the support portions 122 and 132 of the second finger 120 and the third finger 130 are respectively provided on the base portion 140 by two specific turning axes, in this embodiment, turning axes O2 and O3. It is pivotably supported on the top.

  A motor 141 is disposed on the base 140 as a rotational drive source, and the fingers 120 and 130 are turned by transmitting the driving force of the motor 141 to the turning axes O2 and O3 via a drive / transmission system described later.

  For example, as shown in FIG. 3, the second finger 120 is turned in the T2 direction around the turning axis O2, and the forward and backward (closed, open) direction of the fingertip 124 is changed between the P2 axis and the Q2 axis. Can do. Similarly, the third finger 130 can turn in the T3 direction around the turning axis O3, and the forward / backward (closed, open) direction of the fingertip 134 can be changed between the P3 axis and the Q3 axis. In FIG. 3, the positions of the fingertips 124 and 134 when the fingers 120 and 130 are turned to the positions of the P2 axis and the Q3 axis around the turning axes O2 and O3 are indicated by broken lines.

  In the present embodiment, the support devices 122 and 132 of the two fingers 120 and 130 are turned in opposite directions by the transmission device 149 described later via two specific turning axes O2 and O3, respectively. Accordingly, the direction of relative displacement of each of the two fingers 120 and 130 with respect to, for example, the base 140 and the finger 110 is perpendicular to a straight line passing through the midpoint C0 of the pivot axes O2 and O3 and connecting the two pivot axes. It is controlled to have a symmetrical angle with respect to the line C.

  In the present embodiment, the direction of displacement of the support portion 112 of the first finger 110 that does not have the turning mechanism, that is, the axis of relative displacement with respect to the other fingers (120, 130) is the turning axes O2, O3. It coincides with a reference line C that passes through the midpoint C0 of the pivot axis and is orthogonal to a straight line connecting the two pivot axes.

  In the present embodiment, it is preferable to prevent the second finger 120 and the third finger 130 from interfering with each other when the second finger 120 and the third finger 130 are turned. For example, in FIG. 3, when the finger 120 is further rotated in the clockwise direction from the P2 axis and the finger 130 is further rotated in the counterclockwise direction from the P3 axis, the links of the fingers and the support portions 122 and 132 can come into contact. There is sex. Further, the turning position in which the finger 120 is further turned counterclockwise from the Q2 axis and the finger 130 is further turned clockwise from the Q3 axis is the practicality of the gripping operation performed in cooperation with the first finger 110. May be reduced. Therefore, in the case of the present embodiment, it is preferable that the turning ranges of the second finger 120 and the third finger 130 or the support portions 122 and 132 are set to, for example, the P2 axis to the Q2 axis shown in FIG. A limiting mechanism (not shown) that limits the range from the axis to the Q3 axis is arranged. For example, the limiting mechanism includes the above-described pins (not shown) standing on the circumference of the turning axes O2 and O3, and these pins at the rotation angles corresponding to the P2, Q2, and P3 and Q3 axes, respectively. It can comprise a stopper member (not shown) that stops. These stopper members are arranged at positions of rotation angles corresponding to the P2 axis, the Q2 axis, the P3 axis, and the Q3 axis of the base 140, respectively. Moreover, you may implement | achieve the limiting mechanism of the same meaning by cooperation of the edge part of the support parts 122 and 132, the stopper member not shown which latches them, respectively, etc., for example.

  4 and 5 show a configuration of a turning device that turns the second finger 120 and the third finger 130. FIG. FIG. 4 is a perspective view showing a schematic configuration of the transmission device 149 that omits the outer shell of the base portion 140 and distributes the motor 141 and its rotational power to the turning axes O2 and O3 of the fingers 120 and 130. FIG. 5 shows a schematic configuration of the transmission device 149 from below the base 140.

  In the present embodiment, as shown in FIG. 4, swivel axes O2 and O3 coupled to fingers 120 and 130, respectively, and a plurality of wave gear transmissions (wave gear reducers 145A and 145B coupled to the swivel axes, respectively. ). And the output of the motor 141 as a rotational drive source is transmitted to each wave gear transmission (wave gear reducer 145A, 145B) by the transmission device 149.

  As shown in FIG. 4, the transmission device 149 of this embodiment includes, for example, a gear 142 coupled to an output shaft of a motor 141, gears 144A and 144B coupled to input shafts of wave gear reducers 145A and 145B, and the like. Gears 143A and 143B disposed between the two. In the present embodiment, these gears are spur gears (flat gears), but the transmission device 149 may be constituted by a pulley and a belt, and a worm gear may be used for some of the gears.

  In the present embodiment, as shown in FIG. 4, the transmission device 149 is changed from a gear 142 provided on the output shaft of the motor 141 to a gear 144B coupled to the input shaft of the wave gear reducer 145B via the intermediate gear 143B. Communicated. Intermediate gear 143B is transmitted to gear 144A coupled to the input shaft of wave gear reducer 145A via intermediate gear 143A. In order to realize the turning control of the gripping portion of the present embodiment, preferably, the intermediate gears 143A and 143B have the same number of teeth. As a result, the gear ratio from the motor 141 to the wave gear reducer 145A and the gear ratio to the wave gear reducer 145B are the same gear ratio, and the rotational drive directions are opposite to each other. In the present embodiment, the rotational driving force of the motor 141 is thus transmitted in reverse rotation to the input shafts (146A and 146B in FIG. 5) of the wave gear reducers 145A and 145B.

  FIG. 5 shows the drive / transmission system of FIG. 4 from below. FIG. 6 shows a cross-sectional structure of the drive / transmission system of FIG. 4 disposed in the outer shell of the base 140. As shown in FIGS. 5 and 6, the branched rotational driving force is transmitted to the turning shaft O2 ′ on the input side of the wave gear reducer 145A via the gear 144A, and is transmitted to the second finger via the wave gear reducer 145A. It is transmitted to the rotating shaft 147A (O2) provided on the support portion 122 of 120. The rotation shaft 147A is supported by a bearing 146A for receiving a load applied to the fingertip (124) of the finger (120) on the support portion 122 side.

  In particular, in this transmission system, as indicated by the alternate long and short dash line, the turning axis O2 of the finger 120 and the turning axis O2 ′ on the input side of the wave gear reducer 145A are arranged coaxially. In order to establish such a coaxial relationship, for example, the wave gear reducer 145A is preferably mounted on the base 140 via a position adjusting mechanism (not shown in detail) so that the mounting position in the horizontal plane can be adjusted.

  The transmission system of the third finger (130) to the support portion 132 is the same as described above, and the rotational driving force input to the gear 144B is the rotation axis O3 ′ on the input side of the wave gear reducer 145B to the wave gear reduction. It is transmitted to the rotary shaft 147B (O3) via the machine 145B. The rotating shaft 147B is supported by a bearing 146B for receiving a load applied to the fingertip (125) of the third finger (130). Also in the transmission system on the third finger (130) side, as indicated by the alternate long and short dash line, the turning axis O3 of the finger 130 and the turning axis O3 ′ on the input side of the wave gear reducer 145B are arranged coaxially. In order to establish such a coaxial relationship, for example, the wave gear reducer 145B is also preferably mounted on the base 140 via a position adjustment mechanism (not shown in detail) so that the mounting position in the horizontal plane can be adjusted. It is good.

  In this embodiment, by adjusting the horizontal position of the wave gear reducers 145A and 145B, the coaxiality of the respective axes O2 and O2 ′ and O3 and O3 ′ is established. However, in order to guarantee the coaxiality of these axes, a shaft joint or the like may be interposed in a part of the transmission system. In that case, there is a possibility that the step of adjusting the horizontal position of the wave gear reducers 145A, 145B may be omitted.

  As described above, in the hand 100 according to the present embodiment, the plurality of fingers 110, 120, and 130 are displaced relative to each other in the closing direction or the opening direction to grip or release the gripping object. The hand 100 includes turning axes O2 and O3 for turning the fingers 120 and 130 with respect to the base (140) and changing the direction of displacement of the fingers 120 and 130. Further, a transmission device 149 for distributing the driving force of the motor 141 to the plurality of turning axes O2 and O3 is disposed. Then, the driving force distributed by the transmission device 149 is transmitted to each swivel shaft via wave gear reducers 145A and 145B that are transmitted to the swivel shafts respectively disposed between the transmission device 149 and the swivel shafts O2 and O3. Is transmitted to.

  According to the above configuration, the wave gear reducers 145A and 145B are used as the speed reduction means included in the turning devices for the fingers 120 and 130 as the gripping portions. For this reason, a required reduction ratio can be obtained without arranging a reduction gear using multi-stage gears. The wave gear reducer has the advantage that the number of meshing stages and the corresponding occurrence of backlash are generally smaller than those of a reducer using a normal multi-stage gear. In addition, the wave gear reducer has an advantage of being small and light, and therefore can be easily arranged in a portion where the mounting space is relatively limited, such as the base 140 of the gripping device (hand 100). Moreover, in general, a wave gear reducer can take a larger reduction ratio more easily than a reducer using multistage gears that can be mounted in the same mounting space. Even when this large reduction ratio is taken into consideration, even if a rotation angle error occurs in the primary (input) side of the wave gear reducer, for example, in the above configuration, several stages of gear transmission of the transmission device 149, the rotation angle The influence of the error on the secondary (output) side of the wave gear reducer can be small. For this reason, according to the configuration of the present embodiment, the turning mechanism of the gripping part (finger) of the gripping device (hand) can be made compact and lightweight, and the turning control of the gripping part (finger) can be realized with extremely high accuracy. Can do.

  In the present embodiment, a wave gear reducer such as a harmonic drive (registered trademark), which is preferably configured with about one gear transmission stage, can be suitably used as the wave gear reducer.

<Grip method of the object>
A hand 100 (grip device) having fingers 120 and 130 that can be turned as a grip portion of the present embodiment is attached to the tip of a robot arm, for example, the arm main body 200 of FIG. 1, and is suitable for assembling articles such as industrial products. Can be used. 7 and 8 show an example of control of the gripping operation performed by using the turning device of the hand 100 described above.

  FIG. 7 illustrates the state of the hand 100 at two different control timings of [STEP 1] and [STEP 2]. In [STEP 1] and [STEP 2], the hand 100 is already positioned at the picking position with respect to the workpiece W1 that is the object to be grasped by the arm body 200 of FIG. In both [STEP 1] and [STEP 2], the hand 100 is positioned at the same position by the arm body 200. In order to show this, [STEP 1] and [STEP 2] in FIG. 7 are shown so that the reference position of the hand 100, for example, R (a dashed-dotted line) on the left side surface of the base 140 in FIG.

  In the gripping operation of the workpiece W1, first, as shown in [STEP1] in FIG. 7, the hand 100 is positioned at the picking position with respect to the workpiece W1. First, the second and third fingers 120 and 130 are positioned. At this time, the CPU 501 of the hand control device 500 controls the relative displacement of the second and third fingers 120 and 130 with respect to the first finger 110 by a position control (cnt1) method. For this position control, for example, the detection amount of the rotational drive amount (for example, angle) detected by a rotary encoder or the like arranged in the drive system of the fingers 120 and 130 is used for the movement control of the second and third fingers 120 and 130. Do it by feedback.

  Subsequently, as shown in [STEP 2], the first finger 110 is relatively displaced in the closing direction with respect to the fingers 120 and 130, and the workpiece W1 is gripped. At this time, the movement control (cnt2) of the first finger 110 is performed by position control similar to the above or by gripping force control. In this gripping force control, the movement amount of the first finger 110 is determined based on the detected amount of force detected by a fingertip of the finger 110 or a force sense (force sensor, torque sensor) disposed between the support 112 and the fingertip 114. Do it by feedback.

  8A to 8E show some examples of gripping postures of the fingers 110, 120, and 130 that are possible with the hand 100 of the present embodiment. In the figure, for simplification, only the fingertips 114, 124, and 134 of the first to third fingers 110, 120, and 130 and the workpiece W1 having various cross-sectional shapes are illustrated.

  FIG. 8A shows a gripping posture of each finger suitable for a case where the workpiece W1 has a circular cross section. In FIG. 8A, the second finger 120 and the third finger 130 are turned, and in this case, the angle formed by the direction in which the fingertips 124 of these fingers are displaced is controlled to 120 °. In the configuration of FIG. 3, particularly the configuration in which the moving direction of the finger 110 coincides with a straight line passing through the midpoints of the turning axes O2 and O3 of the fingers 120 and 130, the direction in which the three fingers are relatively displaced is 120 The positional relationship is °.

  The CPU 501 of the hand control device 500 determines the turning angle of the second finger (120) and the third finger (130) as described above, and the direction of relative displacement of the fingertip 124 and the fingertip 134 with respect to the base 140 or the finger 110. Positioning. After positioning the fingertip 124 and the fingertip 134 in the displacement direction via the turning angle of each finger, the work W1 is gripped while the gripping force is controlled by the first finger 110, for example.

  According to the finger arrangement in FIG. 8A, when the workpiece W1 has a circular cross section as shown in the drawing, the workpiece W1 can be gripped in a balanced manner, and in particular, centering control of the gripping position is facilitated. This is because the fingertips 114, 124, and 134 of the fingers (110, 120, and 130) are in a positional relationship in which they are evenly arranged at 120 ° with respect to the circumferential surface of the workpiece W1.

  The gripping posture in FIG. 8B shows how to use the two-finger configuration without using the first finger (110) and the fingertip 114 thereof. The gripping posture in FIG. 8B is suitable when the gripping component grips a small component or the like. In FIG. 8B, the support portions (122, 132) of these fingers (120, 130) are turned so that the displacement directions of the fingertips 124, 134 coincide with the axes Q2, Q3 of FIG. As a result, the angle formed by the axes of the fingertips 124 and the direction of travel of the fingertips 134 is 180 ° and is aligned on a straight line.

  The CPU 501 of the hand control device 500 determines the turning angles of the second finger 120 and the third finger 130 as described above, and positions the direction of relative displacement of the fingertip 124 and the fingertip 134 with respect to the base 140 or the finger 110. After positioning the fingertip 124 and the fingertip 134 in the displacement direction via the turning angle of each finger, these fingers are relatively displaced to grip the workpiece W1. At this time, the finger 120 or 130 is relatively displaced by position control. Further, when a force sensor is arranged on the finger 120 or 130, grip force control can be interposed.

  FIGS. 8C to 8E show gripping postures when the workpiece W1 has, for example, two surfaces parallel to each other and grips the workpiece W1 having different forms gripped from the respective gripping surfaces. ing. The workpiece W1 in FIG. 8C has a relatively short side in the direction perpendicular to the direction of displacement of the fingertip 114 of the first finger (110) (lateral direction in the figure). Conversely, the workpiece W1 in FIG. The side in the direction (lateral direction in the figure) perpendicular to the displacement direction of the fingertip 114 of the first finger (110) is relatively long. Further, the workpiece W1 in FIG. 8E has a relatively long side in a direction (lateral direction in the drawing) perpendicular to the displacement direction of the fingertip 114 of the first finger (110). Moreover, the workpiece W1 in FIG. 8E has a portion where the lengths of the sides in the direction (vertical direction in the drawing) parallel to the displacement direction of the fingertip 114 of the first finger (110) are different.

  In the workpiece W1 as shown in FIG. 8C, the angle formed by the displacement directions of the fingertips 124 and 134 of the second and third fingers (120, 130) is 0 °, for example, the axes P2, P3 in FIG. Thus, control is performed so that the displacement directions of these fingertips become parallel. Thereby, for example, the rectangular parallelepiped workpiece W1 can be stably held by the three-point support of the fingertips 114, 124, and 134.

  The CPU 501 of the hand control device 500 determines the turning angle of the second finger (120) and the third finger (130) as described above, and the direction of relative displacement of the fingertip 124 and the fingertip 134 with respect to the base 140 or the finger 110. Positioning. After positioning the fingertip 124 and the fingertip 134 in the displacement direction via the turning angle of each finger, the work W1 is gripped while the gripping force is controlled by the first finger 110, for example.

  Further, in the case of the workpiece W1 having a shape as shown in FIGS. 8D and 8E, the displacement direction of the second and third fingers (120, 130) is more than that in the parallel arrangement as shown in FIG. 8C. As shown in the drawing (with a turning angle similar to that shown in FIG. 8A), it may be more appropriate to arrange the components inclined with respect to each other. 8D and 8E, for example, the corners of the fingertip 124 and the fingertip 134 are brought into contact with the workpiece W1 to grip the workpiece. By performing such turning control, the distance L between the fingertip 124 and the fingertip 134 can be increased, and the tilt error of the workpiece W1, for example, the positioning error of the workpiece center with respect to the base (140) of the hand 100 can be reduced, and the workpiece W1 can be accurately performed. Can be gripped.

  The CPU 501 of the hand control device 500 determines the turning angles of the second finger (120) and the third finger (130) as described above. In that case, the direction of relative displacement of the fingertip 124 and the fingertip 134 with respect to the base 140 or the finger 110 is, for example, about 45 ° to 6, 70 ° with respect to the reference line C (FIG. 3). After positioning the fingertip 124 and the fingertip 134 in the displacement direction via the turning angle of each finger, the CPU 501 determines the displacement amount of the fingertip 124 and the fingertip 134 by position control according to, for example, the shape and size of the workpiece W1 that has been previously determined. Control and advance to a position as shown in FIGS. Thereafter, the workpiece W1 is gripped while the gripping force is controlled with the first finger 110, for example. 8D and 8E, the CPU 501 calculates the amount of displacement by which the fingertip 124 and the fingertip 134 are advanced based on the turning angle of each finger and the necessary thickness dimension of the work W1. Can be determined by

  As described above, according to the hand 100 (gripping device) having the swiveling device for the fingers 110, 120, and 130 (gripping unit) of the present embodiment, each of the fingers can be selected according to the size or cross-sectional shape of the workpiece W1. Various gripping postures and directions of relative displacement of each finger can be selected. For this reason, it is possible to deal with various workpieces W1 having different dimensions, cross-sectional shapes, and the like and perform reliable and highly accurate gripping control.

<Robot control method>
FIG. 9 shows an example of a robot control method when the workpiece W1 is gripped in the robot system as shown in FIG. 9 is executed by the CPU 501 of the hand control device 500 or the CPU of the arm control device 400, for example. The control procedure in FIG. 9 can be stored in, for example, the ROM 501 (or the ROM on the arm control device 400 side) as a control program that can be executed by these CPUs. In FIG. 1, for convenience, the arm control device 400 and the hand control device 500 are separately illustrated, but these may be configured as an integrated control device. Further, the control program schematically shown in FIG. 9 may be stored in various detachable flash memories (not shown) or optical disks, and supplied to the apparatus shown in FIG. In this case, these computer-readable recording media constitute the recording medium of the present invention. Further, the control program schematically shown in FIG. 9 may be supplied via a network via a network (not shown).

  In the control of FIG. 9, the CPU 501 of the hand control device 500 (or the CPU of the arm control device 400) performs the following control.

  The control loop of steps S11 and S12 in FIG. 9 constitutes a position and orientation control step of controlling the arm body 200 (robot arm) and moving the hand 100 to a picking position where the work W1 can be gripped (for example, a position directly above the work). At this time, for example, the position and orientation of each part of the arm main body 200 are controlled based on the joint angle obtained via a rotary encoder or the like disposed at each joint of the arm main body 200. In step S12, it is determined whether or not the hand 100 has moved to the desired picking position by kinematic calculation based on the angles of the joints of the arm body 200. When the hand 100 moves to the picking position, the control loop is terminated.

  In the loop of steps S13 and S14, the motors 121, 131, and 141 of the hand are controlled to turn the fingers (120, 130) that can turn, and the displacement directions of the fingertips 124 and 134 are determined (turning control process). For example, at this time, the turning angle of the fingers (120, 130) is determined according to the shape and dimensions of the workpiece W1 as described with reference to FIG. After the turning angle of the finger (120, 130) is determined, the fingertips 124, 134 are further advanced (or retracted) based on the shape and dimensions of the workpiece W1. In step S14, it is detected whether or not the fingertips 124 and 134 have reached the target position. When the fingertips 124 and 134 reach the target position, the control loop is terminated.

  In the control loop of steps S15 and S16, the motor 111 is driven and the fingertip 114 is moved (advanced) to press the workpiece W1 that is the object to be gripped and pressed against the fingertips 124 and 134 (gripping control step). . FIG. 9 shows a case where gripping force control is performed. In step S16, it is detected whether or not the gripping force detected via a force sensor (not shown) has reached a predetermined value or a predetermined range. If a predetermined gripping force is obtained in step S16, this control loop is terminated. In addition, when controlling the fingertip 114 by position control, in step S16, the position control determination similar to, for example, step S13 may be performed.

  As described above, for example, in the robot system as shown in FIG. 1, the workpiece W1 can be gripped, moved to the position of the workpiece W2, and an assembly operation can be performed for assembling the workpiece W2. Can be manufactured.

  In the turning mechanism of the gripping part (finger) in the gripping device of the present embodiment, wave gear reducers (145A, 145B) for the respective fingers are arranged at the subsequent stage of the transmission device 149, respectively. For this reason, even if there is an error due to backlash or elongation caused by gears, belts of the transmission device 149 (same when a chain is interposed), etc., the turning axis O2 of each turning finger (120, 130), The rotation angle generated at the position of the transmission stage of O3 can be greatly reduced. Theoretically, the angle error generated at the stage of the transmission device 149 is 1 / (the reduction ratio of the wave gear reducer) at the position of the transmission stage of the turning axes O2 and O3 of the turning fingers (120, 130). Reduced.

  The wave gear reducers (145A, 145B) generally have a small number of internal transmission stages, a small backlash, and a compact product having a large reduction ratio can be easily obtained. For this reason, according to this embodiment, positioning control of the holding part (finger) of a holding device (hand) can be performed with high accuracy. Therefore, according to the gripping device (hand) of the present embodiment, various gripping forms can be realized, and highly accurate gripping control can be performed corresponding to the shape and dimensional difference of the gripping object.

  Further, in this embodiment, wave gear reducers (145A, 145B) for each finger are arranged at the subsequent stage of the transmission device 149, and the rotational driving force of the drive source is distributed before deceleration. Thereby, the load applied to the transmission device 149 can be reduced, and for example, there is a possibility that the strength and rigidity of the constituent members of the transmission device 149 can be reduced. For this reason, there is a possibility that inexpensive, small and lightweight parts can be selected for the transmission device 149, and as a result, reduction in size and weight of the entire gripping device (hand) or cost reduction can be expected.

  Further, in the gripping device (hand) of this embodiment, after the second and third fingers that can be turned are turned, when the forward or backward control of these fingers is performed, the finger is positioned at a desired position by position control. Thereafter, the gripping force can be controlled with the first finger to control the object to be gripped. As a result, the object is brought close to the second finger and the third finger that have been positioned by the first finger, and the gripping position of the gripping object is determined. By performing control combining such position control and gripping force control, the relative position between the gripping device (hand) and the intended gripping part of the gripping object (workpiece) can be accurately controlled, and the gripping position and gripping can be controlled. The force can be controlled with high accuracy.

  The present invention supplies 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 one or more processors in a computer of the system or apparatus read and execute the program. It can also be realized by processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  DESCRIPTION OF SYMBOLS 100 ... Hand, 110, 120, 130 ... Finger, 111, 121, 131, 141 ... Motor, 112, 122, 132 ... Support part, 113, 123, 133 ... Link, 114, 124, 134 ... Finger tip, 140 ... Base , 142, 143, 144 ... gear, 145A, 145B ... wave gear reducer, 146 ... bearing, 149 ... transmission device, 500 ... hand control device, 501 ... CPU, 502 ... ROM, 503 ... RAM.

Claims (9)

In a gripping device that grips or releases a gripping object by relatively displacing a plurality of gripping parts supported by a base in a closing direction or an opening direction,
A swivel shaft that swivels the grip portion with respect to the base and changes a direction of relative displacement of the grip portion;
A rotational drive source;
A wave gear transmission that is disposed between the turning shaft and the rotation drive source, shifts an output of the rotation drive source, and transmits the output to the turning shaft;
A gripping device provided with a turning mechanism including:   2. The gripping device according to claim 1, wherein the plurality of swiveling shafts respectively coupled to the plurality of gripping portions, the plurality of wave gear transmissions respectively coupled to the swiveling shafts, and an output of the rotation drive source. And a transmission device that transmits a plurality of wave gear transmissions to the gripping device.   The gripping device according to claim 2, wherein the transmission device is configured to specify the output of the rotational drive source at the same speed ratio so as to rotate two specific turning shafts in a reverse direction among the plurality of turning shafts. A gripping device for transmitting to a wave gear transmission coupled to the two pivot shafts.   The gripping device according to claim 3, wherein the two gripping portions respectively coupled to the specific two pivot shafts are swung in opposite directions, whereby the relative displacement directions of the two gripping portions are A gripping device that is controlled to have a symmetric angle with respect to a reference line that passes through a midpoint of the two pivot axes and is orthogonal to a straight line that connects the two pivot axes.   A robot provided with a robot arm that changes a position and orientation of the gripping device when the gripping device according to claim 1 grips the gripping object. A robot control method for controlling a robot according to claim 5,
A position and orientation control step of controlling the gripping device to a position and orientation capable of gripping the gripping object by the robot arm;
A turning control step of determining a turning angle of the gripping portion of the gripping device by the turning mechanism;
A grip control step of relatively displacing the plurality of grip portions to grip or release the grip target; and
A robot control method including:   A control program for causing a control device that controls the gripping device or the robot arm to execute each step according to claim 6.   A computer-readable recording medium storing the control program according to claim 7.   An article manufacturing method for assembling an article by controlling the position and orientation of the gripping device with the robot arm included in the robot according to claim 5 and gripping or releasing the gripping object.

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