Gripper

Abstract

A gripper according to the present disclosure comprises: a finger portion (110); a rotary fingertip (120) provided at a tip of the finger portion (110) and coming into direct contact with a target; a rotary motor (130) serving as a rotational power generator for the rotary fingertip (120); and a finger extension / contraction motor (140) serving as a power generator for moving the rotary fingertip (120) in an extension / contraction direction of the finger portion (110). The rotary fingertip (120) performs an operation of pressing against and rotating the target as a pre-gripping preparation operation.

Description

[Technical field]

[0001] The disclosed technology relates to grippers. [Background technology]

[0002] A gripper is a type of end effector that is attached to the end of a robot arm. As the name suggests, a gripper is an end effector whose purpose is to grip an object. The object that a gripper grips is sometimes called a target. Hereinafter, in this specification, the object to be gripped is called the "target."

[0003] Patent Document 1 discloses a cable attachment device and a robot used in cable attachment work. The cable attachment device in Patent Document 1 is a gripper. The gripper in Patent Document 1 uses a suction cup to adsorb the target cable placed on a stage (sample table) and lifts it slightly above the stage to make it easier to grip, and then clamps and grips the cable with two fingers that move in parallel, more specifically, with two rotating bodies (gripping rollers) provided at the tips of the two fingers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 091246 Summary of the Invention [Problem to be solved by the invention]

[0005] When applying robot technology to "automation of cable installation work," it is desirable to avoid situations where the robot fails to grip the cable as much as possible. For example, a situation where the robot fails to grip the cable may occur when the robot starts to pinch the cable while not in a position or posture (hereinafter simply referred to as "position and posture") that makes it easy to hold the cable. The problem of controlling a robot to a position and posture that makes it easy to hold a cable generally comes down to the problem of solving inverse kinematics. For humans, it is easy and unconsciously to move one's hand to a target position and posture, but for robots, this is not easy. The program that controls the robot must solve the inverse kinematics that controls the robot's end effector from the current position and posture to the target position and posture, and must also verify that the robot does not interfere with other objects when controlling the robot's end effector to the target position and posture.

[0006] By the way, if you observe closely when a person uses chopsticks to pick up a bean, you will notice that before picking up the bean, they may use the chopsticks to move the bean slightly to a place that is easier to hold, or to change the orientation slightly to make it easier to grasp. This action of changing the position and posture of the target to make it easier to hold before grasping it is referred to here as the "pre-grasp preparation action." If a gripper attached to the end of a robot's arm can successfully perform pre-grasp preparation operations, there is no need to solve the inverse kinematics or perform an interference check. The disclosed technology aims to provide a gripper suitable for pre-grasp preparation operations. If pre-grasp preparation operations can be performed, there is no need to solve the inverse kinematics or perform an interference check, and it is possible to move on to the operation of gripping a target. [Means for solving the problem]

[0007] The gripper according to the disclosed technology includes a finger portion, a rotating fingertip provided at the tip of the finger portion and in direct contact with a target, a rotation motor serving as a rotation power generator for the rotating fingertip, and a finger extension motor serving as a power generator for moving the rotating fingertip in a direction in which the finger portion extends and retracts. The rotating fingertip performs the following preparatory motion before gripping: Using a rotation motor and a finger extension motor It involves pressing and rotating against a target. Effect of the Invention

[0008] Because the gripper according to the disclosed technology has the above-described configuration, it can perform pre-grasping preparation operations and can move on to the operation of gripping a target without the need to solve inverse kinematics or perform interference checks. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a first external view showing the configuration of a gripper 100 according to the first embodiment. [Diagram 2] FIG. 2 is a second external view showing the configuration of the gripper 100 according to the first embodiment. [Diagram 3] FIG. 3 is an enlarged view showing a part of the configuration of the gripper 100 according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing a control flow of the gripper 100 according to the first embodiment. [Diagram 5] FIG. 5 (FIGS. 5A and 5B) are explanatory diagrams showing an example of control of the gripper 100 according to the first embodiment. [Figure 6] FIG. 6 (FIGS. 6A, 6B, and 6C) is a first explanatory diagram showing the "pressing and rotating operation" which is a technical feature of the gripper 100 according to the disclosed technique. [Figure 7] FIG. 7 is a second explanatory diagram showing the "pressing and rotating operation" which is a technical feature of the gripper 100 according to the disclosed technique. [Figure 8] FIG. 8 is a first explanatory diagram showing an example of the operation of the gripper 100 according to the second embodiment. [Figure 9] FIG. 9 is a second explanatory diagram showing an example of the operation of the gripper 100 according to the second embodiment. [Figure 10] FIG. 10 is an explanatory diagram showing a structural example in which the suction cup type rotating fingertip 120B constituting the gripper 100 according to the second embodiment simultaneously realizes the functions of suction and rotation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] To make it easier for the robot arm to grip the target, the sample stage may be modified, for example by vibrating the sample stage to align the orientation of multiple targets at the same time. Since the vibration of the sample stage is an operation for changing the position and posture of the target to make it easier to hold before gripping, it can be said to be a pre-grasp preparation operation in a broad sense for the robot system including the sample stage. This specification describes the technical features of the gripper 100 according to the disclosed technology, and clarifies the pre-grasp preparation operation performed by the gripper 100.

[0011] Embodiment 1 Fig. 1 is a first external view showing the configuration of a gripper 100 according to embodiment 1. As shown in Fig. 1, the gripper 100 according to embodiment 1 includes a finger portion 110, a rotating fingertip 120, a rotation motor 130, a group of rotation gears 132, a finger extension / retraction motor 140, a finger extension / retraction pinion 142, and a finger extension / retraction rack 144. Fig. 2 is a second external view showing the configuration of the gripper 100 according to the first embodiment. Fig. 2 is an external view of the gripper 100 when viewed from an angle different from that of Fig. 1. As in Fig. 1, Fig. 2 shows the finger portion 110, the rotating fingertip 120, the rotation motor 130, the rotation gear group 132, the finger extension motor 140, the finger extension pinion 142, and the finger extension rack 144.

[0012] <Finger portion 110 constituting gripper 100> The finger portion 110 constituting the gripper 100 is a component equivalent to a human finger, figuratively speaking. In the technical field of robotics, the part equivalent to the finger portion 110 is sometimes called a "claw." The size, shape, and material of the finger portion 110 may be selected and designed according to the purpose of use, specifically, according to the physical properties of the target. Although two finger portions 110 are shown in FIG. 1 and FIG. 2, the disclosed technology is not limited thereto. The gripper 100 according to the disclosed technology may include three or more finger portions 110.

[0013] <Rotating fingertip 120 that constitutes gripper 100> The rotating fingertip 120 constituting the gripper 100 is provided at the tip of the finger portion 110 and is a component that directly contacts the target. The gripper 100 according to the disclosed technology can rotate the rotating fingertip 120 by including a rotation motor 130 and a group of rotation gears 132 described later (see FIG. 3). The rotational motion of the rotating fingertip 120 can be used to feed the gripped cable Ca and to change the position and posture of the target as a pre-grasping preparation motion. The motion of feeding the gripped cable Ca is a motion that assumes a process of fitting the cable Ca to a terminal (sometimes referred to as a "connector fitting motion"). In this specification, when referring to a specific thing, that is, when emphasizing that it is a proper noun, a symbol is added after the name, such as "cable Ca," to distinguish it from an ordinary noun. In this specification, the cable Ca is specifically assumed to be a flexible flat cable. The size and material of the rotating fingertip 120 may be designed according to the physical properties of the target. The rotating fingertip 120 may be made of silicon, for example.

[0014] Rotation motor 130 constituting gripper 100 The rotation motor 130 constituting the gripper 100 is a component that serves as a rotation power generator for the rotating fingertip 120. Fig. 3 is an enlarged view showing a part of the configuration of the gripper 100 according to the first embodiment. Fig. 3 shows the rotation motor 130 and a group of rotation gears 132, which will be described later. The rotating fingertip 120 is connected to the rotation motor 130 via the group of rotation gears 132.

[0015] <<Rotation gear group 132 constituting the gripper 100>> The rotation gear group 132 that constitutes the gripper 100 is a component made up of multiple gears. The rotation gear group 132 has a role of adjusting the torque and speed at which the rotating fingertip 120 is rotated. The gear ratio of the rotation gear group 132 may be appropriately designed according to the characteristics of the rotation motor 130 and the physical properties of the target.

[0016] <Finger extension motor 140 constituting gripper 100> The gripper 100 according to the disclosed technology can operate as if the finger were expanding and contracting. The finger extension motor 140 constituting the gripper 100 is a component that, figuratively speaking, is a power generator that moves the rotating fingertip 120 in the direction in which the finger is expanding and contracting. Although the finger portion 110 does not actually need to expand and contract, in this specification, the direction in which the finger is expanding and contracting as if the finger is expanding and contracting is referred to as the "direction in which the finger portion 110 expands and contracts." In fact, if the finger portion 110 is considered to include the rotating fingertip 120, the finger portion 110 expands and contracts as a whole. As shown in FIG. 1 and FIG. 2, the finger extension motor 140 moves the rotating fingertip 120, the rotation motor 130, and the rotation gear group 132 in the direction in which the finger portion 110 expands and contracts via a finger extension pinion 142 and a finger extension rack 144, which will be described later.

[0017] Finger extension pinion 142 and finger extension rack 144 that constitute gripper 100 The finger extension pinion 142 and finger extension rack 144 that make up the gripper 100 are mechanisms that convert the rotational force of the finger extension motor 140 into linear motion. As their names suggest, the finger extension pinion 142 is a pinion, and the finger extension rack 144 is a rack. The finger extension motor 140, the finger extension pinion 142, and the finger extension rack 144 realize linear motion of the rotating fingertip 120, the rotation motor 130, and the rotation gear set 132.

[0018] Fig. 4 is a flowchart showing a control flow of the gripper 100 according to embodiment 1. As shown in Fig. 4, the control flow of the gripper 100 includes pressing the rotating fingertip 120 against the cable Ca (ST1), image processing of the cable Ca (ST2), calculation of the position and posture of the cable Ca (ST3), calculation of the gripping angle difference (Δθ) of the cable Ca (ST4), operation processing for rotating the cable Ca (ST5), and operation processing for gripping the cable Ca (ST6). The gripper 100 is controlled by a controller (not shown in the figure). The controller is specifically configured by a processing circuit. Each processing step (ST1 to ST6) in the flowchart shown in Fig. 4 can be said to represent a processing step of the controller.

[0019] The pressing (ST1) of the rotating fingertip 120 against the cable Ca may be performed under a control called "pressing control." Pressing control is known in the technical field of motor control as a combination of torque control and speed control, and is a control that can suppress the instantaneous speed increase that occurs when switching from the previous position control to torque control.

[0020] Image processing (ST2) for the cable Ca is a processing step in the case where the gripper 100 is controlled based on real-time images obtained by a camera. Although not shown, the disclosed technology may control the gripper 100 using camera images in this manner. The method of processing image information obtained from a camera and feeding back the results to control a robot is sometimes called image feedback control.

[0021] Calculating the position and orientation of the cable Ca (ST3) is a processing step for calculating the position and orientation of the cable Ca, which is information used for image feedback control. Expressed in terms of modern control theory, the position and orientation of the cable Ca can be said to be the state of the control object observed by the controller. Strictly speaking, the control object of the controller is directly the gripper 100, but the cable Ca gripped by the gripper 100 can also be considered to be an indirect control object.

[0022] Calculating the gripping angle difference (Δθ) of the cable Ca (ST4) is a processing step for calculating the gripping angle difference (Δθ) of the cable Ca, which is information used for image feedback control. FIG. 5 (FIG. 5A and FIG. 5B) are explanatory diagrams showing an example of control of the gripper 100 according to the first embodiment. FIG. 5A shows a camera image at the current time, showing the current position and posture of the cable Ca. FIG. 5B shows a target position and posture of the cable Ca. That is, in the example shown in FIG. 5, the target position and posture of the cable Ca is one in which the longitudinal direction of the cable Ca coincides with the up-down direction of the camera image, as shown in FIG. 5B. The gripping angle difference (Δθ) of the cable Ca is defined as the difference between the current state and the target state, as shown in FIG. 5A.

[0023] In the field of control, it is common to subtract a target state from a current state to obtain a new state variable. In particular, when dealing with nonlinear systems, a process called "linearization around an equilibrium point" or "linearization around an equilibrium state" is a common method. In linearization around an equilibrium state, the error obtained by subtracting the target state (equilibrium state) from the current state is also used as a new state variable. Note that the grip angle difference (Δθ) of the cable Ca does not represent all of the errors obtained by subtracting the target state from the current state. For example, if the cable Ca is considered to be a rigid body having six degrees of freedom in a three-dimensional space, it is considered that there are five states in addition to the grip angle (θ) that can be directly grasped from the camera image. In this specification, the grip angle difference (Δθ) of the cable Ca is merely shown as the most dominant state variable, and in reality, other state variables, for example, state variables related to position and state variables related to other angles, are used.

[0024] The operation process (ST5) of rotating the cable Ca, in combination with the pressing of the rotating fingertip 120 against the cable Ca (ST1), is a processing step that realizes the "pressing and rotating operation" of the gripper 100 according to embodiment 1. This pressing and rotating operation is an example of a pre-gripping preparation operation. FIG. 6 (FIG. 6A, FIG. 6B, and FIG. 6C) is an explanatory diagram showing the "pressing and rotating operation" which is a technical feature of the gripper 100 according to the disclosed technology. FIG. 6A shows the state of the gripper 100 when the controller performs pressing (ST1) against the cable Ca by the rotating fingertip 120. The pressing operation against the cable Ca may be performed by one selected from among the multiple rotating fingertip 120 as shown in FIG. 6A. FIG. 6B shows the state of the gripper 100 when the controller performs an operation process (ST5) to rotate the cable Ca. At this time, the rotating fingertip 120 rotates the cable Ca so that the gripping angle difference (Δθ) becomes 0 (zero). FIG. 6C shows the state of the gripper 100 when the controller performs an operation process (ST6) to grip the cable Ca described later. 7 is a second explanatory diagram showing the "pushing and rotating operation" which is a technical feature of the gripper 100 according to the disclosed technology. As described above, the disclosed technology is equipped with the finger extension motor 140, the finger extension pinion 142, and the finger extension rack 144, so that the rotating fingertip 120 can move in the direction in which the finger portion 110 extends and retracts. In FIG. 1 and FIG. 2, the rotating fingertip 120 is located at a position retracted from the tip of the fingertip, but as shown in FIG. 6 and FIG. 7, when the "pushing and rotating operation" is performed, the rotating fingertip 120 is located at the tip of the fingertip. 6 and 7, a suction cup type rotating fingertip 120B according to embodiment 2 is shown instead of the rotating fingertip 120 according to embodiment 1. Details of the suction cup type rotating fingertip 120B will be apparent from embodiment 2.

[0025] The operation process (ST6) of gripping the cable Ca is a processing step that realizes the main functional operation of the gripper 100. Incidentally, in Fig. 6C, the finger portion 110 is shown pinching the so-called edge portion of the cable Ca, but the disclosed technology is not limited to this. The gripper 100 according to the disclosed technology may be controlled to pinch the so-called upper and lower surfaces of the cable Ca, as when a human holds a ticket.

[0026] As described above, the gripper 100 according to the first embodiment has the above-described configuration, and therefore can perform the pressing and rotating operation, which is a pre-grasping preparatory operation, and can move on to the operation of gripping the target without having to solve inverse kinematics or perform an interference check. The gripper 100 according to the disclosed technology may be provided with a means for assisting in gripping a target, such as an electromagnet section (not shown) or a suction cup (not shown). It is considered that the means for assisting in gripping a target can be adapted to a variety of targets if it is based on a principle different from the principle by which the gripper 100 grips a target. Providing an electromagnet section is effective when the target has a nature of sticking to a magnet. The gripping principle of the electromagnet section is magnetic force, which is different from the principle by which the gripper 100 grips a target. The gripping principle of the suction cup is a pressure difference with the atmospheric pressure generated by sucking in air, which is different from the principle by which the gripper 100 grips a target. A suction cup type rotating fingertip 120B having both the function of the rotating fingertip 120 and the function of a suction cup is shown in the second embodiment.

[0027] Embodiment 2 The gripper 100 according to the second embodiment is a modified example of the gripper 100 according to the technology disclosed herein. Unless otherwise specified, the same reference symbols as those used in the first embodiment are used in the second embodiment. Also, in the second embodiment, descriptions that overlap with those in the first embodiment are omitted as appropriate.

[0028] A unique feature of the gripper 100 according to the second embodiment is that it is equipped with a suction cup type rotating fingertip 120B. The suction cup type rotating fingertip 120B is a component that simultaneously functions as a rotating body (gripping roller) and as a suction cup. As shown in Figs. 6 and 7, the suction cup type rotating fingertip 120B is connected to one end of an air hose 150 that delivers sucked air in order to realize the function as a suction cup. Although not shown, the other end of the air hose 150 is connected to an air pump.

[0029] 6 and 7 show an embodiment in which a suction cup type rotating fingertip 120B is provided instead of the rotating fingertip 120, but the disclosed technology is not limited to this. The gripper 100 according to the disclosed technology may be provided with both the rotating fingertip 120 and the suction cup type rotating fingertip 120B at the same time. FIG. 8 is an explanatory diagram showing an example of the operation of the gripper 100 according to the second embodiment. As shown in FIG. 8, the gripper 100 according to the disclosed technology has the rotating fingertip 120 at the tip of the finger portion 110, and may also have a suction cup type rotating fingertip 120B separately. In this case, the pressing and rotating operation is performed by the suction cup type rotating fingertip 120B. When the suction cup type rotating fingertip 120B is separately provided, the gripper 100 according to the disclosed technology has a vertical movement mechanism (not shown) and a rotation mechanism (not shown) for the suction cup type rotating fingertip 120B that are independent of the mechanism that drives the rotating fingertip 120.

[0030] 8, when a separate suction cup type rotating fingertip 120B is provided, the suction cup type rotating fingertip 120B should be installed at a position equidistant from the two rotating fingertips 120. By installing the suction cup type rotating fingertip 120B at such a position, the cable Ca whose position and posture have been adjusted by the pressing and rotating operation can be easily gripped by the two rotating fingertips 120.

[0031] When the gripper 100 according to the present disclosure is provided with a separate suction cup type rotating fingertip 120B, the suction cup type rotating fingertip 120B may not be fixed, and may allow the suction cup type rotating fingertip 120B to have a degree of freedom. FIG. 9 is a second explanatory diagram showing an example of the operation of the gripper 100 according to the second embodiment. The suction cup type rotating fingertip 120B illustrated in FIG. 9 can be driven in parallel to the direction connecting the two rotating fingertips 120. As shown in the right diagram of FIG. 9, the driveable range of the suction cup type rotating fingertip 120B should include positions that are equidistant from the two rotating fingertips 120. By setting the driveable range in this way, the cable Ca whose position and posture have been adjusted by the pressing and rotating operation can be easily gripped by the two rotating fingertips 120.

[0032] Fig. 10 is an explanatory diagram showing an example of a structure that simultaneously realizes the suction and rotation functions of the suction cup type rotating fingertip 120B constituting the gripper 100 according to the second embodiment. As shown in Fig. 10, the gripper 100 according to the second embodiment may include an air hose 150, a bearing 160, and a connecting part 170 in addition to the rotation motor 130 and the rotation gear group 132. The structure of the bearing 160 and the connecting part 170 makes it possible to perform suction by the air hose 150 without leaking air, and to transmit the rotational force by the rotation motor 130 at the same time.

[0033] As described above, the gripper 100 according to the second embodiment has the above-mentioned configuration, and thus, like the gripper 100 according to the first embodiment, it can perform the pushing and rotating operation, which is a pre-grasping preparatory operation, and can move on to the operation of gripping the target without having to solve inverse kinematics or perform an interference check. [Industrial Applicability]

[0034] The disclosed technology can be applied to, for example, a robot that realizes the automation of cable installation work, and has industrial applicability. [Explanation of symbols]

[0035] 100 gripper, 110 finger portion, 120 rotating fingertip, 120B suction cup type rotating fingertip, 130 rotation motor, 132 rotation gear group, 140 finger extension motor, 142 finger extension pinion, 144 finger extension rack, 150 air hose, 160 bearing, 170 connection portion.

Claims

1. A finger portion and A rotating fingertip provided at the tip of the finger portion and in direct contact with the target; A rotating motor that serves as a rotational power generator for the rotating fingertip; a finger extension motor that serves as a power generator for moving the rotating fingertip in a direction in which the finger portion extends and retracts; The rotating fingertip performs a pressing and rotating operation against the target using the rotation motor and the finger extension / retraction motor as a pre-grasping preparation operation. Gripper.

2. A group of rotation gears connected to the rotation motor and adjusting the torque and speed at which the rotating fingertip rotates; A finger extension pinion and a finger extension rack for converting the rotational force of the finger extension motor into a linear motion are further provided. The gripper of claim 1 .

3. A finger portion and A suction cup type rotating fingertip is provided at the tip of the finger and directly contacts the target; A rotating motor that serves as a rotational power generator for the suction cup type rotating fingertip; A group of rotation gears connected to the rotation motor to adjust the torque and speed at which the suction cup type rotating fingertip rotates; an air hose for delivering the aspirated air; a bearing and a joint that simultaneously realize the suction and rotation functions of the suction cup type rotating fingertip; As a pre-grasping preparation operation, the suction cup type rotating fingertip performs a pressing and rotating operation against the target using the rotation motor, the rotation gear group, the air hose, the bearing and the connecting portion, and the up-down movement mechanism of the suction cup type rotating fingertip. Gripper.

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