GRIPPER

Abstract

The gripper according to the presently disclosed technology includes a finger portion (110), a rotary fingertip (120) provided at the tip of the finger portion (110) to directly contact a target, a rotary motor (130) serving as a rotary force generator for the rotary fingertip (120), and a telescopic finger motor (140) serving as a force generator that moves the rotary fingertip (120) in a direction in which the finger portion (110) is extended or retracted, wherein the rotary fingertip (120) performs a pressing-and-rotating operation toward the target as a preparatory operation before grasping.

Description

TECHNICAL FIELDThe present disclosure relates to a gripper.BACKGROUND ARTA gripper is a type of end effector that is fastened to the arm tip of a robot. As the name suggests, a gripper is an end effector that serves to grip an object or an object. The object that the gripper grasps is sometimes referred to as a "target.". Hereinafter, the object gripped by the gripper will be referred to as a "target".Patent Document 1 discloses a cable mounting apparatus and a robot for use in cable mounting work. The cable mounting device according to Patent Document 1 is a gripper. The gripper according to Patent Document 1 sucks a cable having a suction pad, the cable being a target placed on a platform (sample table), slightly drives the cable down from the platform to be easily gripped, and then grips the target by being clamped with two finger portions moving in parallel, or more specifically, with two rotating bodies (gripping rollers) provided at the tip of two finger portions.REFERENCE LISTPATENT LITERATURE[Patent Document 1] WO 2022 / 091246 A1SUMMARY OF THE INVENTIONTECHNICAL PROBLEMWhen using robotics technology to "automate cable assembly operations", it is desirable to avoid, to the greatest extent possible, the situation in which gripping of a cable fails. The situation in which gripping of a cable fails may occur, for example, when a robot starts the operation of clamping the cable in a position and posture (hereinafter, simply referred to as "position posture") that are not suitable for easily gripping the cable.The problem of controlling the robot to be in a position posture in which the cable is easy to hold generally goes beyond the problem of solving the inverse kinematics. In humans, it is easy for him or her to put the hand in a desired position posture without being aware of it, but in robots, it is not so simple. The program for controlling the end effector of the robot needs to solve the inverse kinematics that controls the robot from the current position posture to the target position posture, and needs to verify that the robot does not interfere with other objects in controlling the end effector of the robot to the target position posture.Note that in the observation of people such as pinching and cancelling a bean grain with rods, some may slightly move the bean grain with the rods to a position where it is more easily pinched, or may slightly change the direction of the bean grain with the rods to a direction where it is more easily pinched. Like this operation, the operation of bringing the target before gripping into a position posture in which the clamping is easier is hereinafter referred to as "pre-gripping preparation operation".If the hand attached to the arm tip of the robot can successfully perform the pre-gripping preparation operation, it is not necessary to cancel the inverse kinematics or check the above-mentioned failure. An object of the disclosed technology is to provide a gripper that is suitable for the pre-gripping preparatory operation. If the preparation process can be performed before gripping, it is possible to directly transition to the movement of gripping the target without having to solve the inverse kinematics or perform a fault check.SOLUTION OF PROBLEMThe looper according to the present disclosed technology includes: a finger portion; a rotary fingertip provided at a tip of the finger portion to directly contact a target; a rotary motor serving as a rotational force generator for the rotary fingertip; and a telescopic finger motor serving as a force generator that moves the rotary fingertip in a direction in which the finger portion is extended or retracted, wherein the rotary fingertip performs a pressing and rotating operation on the target as a preparation operation before the gripping.ADVANTAGEOUS EFFECTS OF THE INVENTIONAccording to the technology described above, since the looper has the configuration described above, the preparation operation can be performed before the looper, and it is possible to directly transition to the movement of loopering the target without the need to solve the inverse kinematics or perform a trouble check.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is an external view 1 showing the configuration of a gripper 100 according to Embodiment 1. FIG. 2 is an external view 2 showing the configuration of the gripper 100 according to Embodiment 1. FIG. 3 is an enlarged view showing a part of the configuration of the gripper 100 according to Embodiment 1. FIG. 4 is a flowchart showing a control flow of the gripper 100 according to Embodiment 1. FIGS. 5A and 5B are explanatory diagrams showing examples of control of the gripper 100 according to Embodiment 1. FIGS. 6A, 6B, and 6C are explanatory diagrams 1 showing the "press-and-rotate operation" which is a technical feature of the gripper 100 according to the disclosed technology. FIG. 7 is an explanatory diagram 2 showing the "press-and-rotate operation" that is the technical feature of the gripper 100 according to the disclosed technology. FIG. 8 is an explanatory diagram 1 showing an example of an operation of a gripper 100 according to Embodiment 2. FIG. 9 is an explanatory diagram 2 showing an example of an operation of the gripper 100 according to Embodiment 2. FIG. 10 is an explanatory diagram showing a structural example that simultaneously satisfies functions of suction and rotation of the suction cup-like rotary fingertip 120B included in the gripper 100 according to Embodiment 2.DESCRIPTION OF THE EMBODIMENTSTo facilitate a robot arm gripping a target, a sample stand may be designed to be capable of vibrating the targets to simultaneously align the orientation of the targets. In the broader sense, since the swinging of the sample stand is also an action of bringing the target into a position posture easier to clamp the target before gripping, this action could also be classified as the pre-gripping preparation operation for a sample stand robot system. This specification describes the technical features of the gripper according to the disclosed technology and illustrates the pre-gripping preparation operation performed by the gripper 100.Embodiment 1.FIG. 1 is an external view 1 showing the configuration of a gripper 100 according to Embodiment 1. As illustrated in FIG. 1, the looper 100 according to Embodiment 1 includes a finger portion 110, a rotary fingertip 120, a rotary motor 130, a set of rotary gears 132, a telescopic finger motor 140, a telescopic finger pinion 142, and a telescopic finger rack 144.FIG. 2 is an external view 2 showing the configuration of the gripper 100 according to Embodiment 1. FIG. 2 is a view of the gripper 100 from a different angle than shown in FIG. 1. As in FIG. 1, the finger portion 110, the rotary fingertip 120, the rotary motor 130, the set of rotary gears 132, the telescopic finger motor 140, the telescopic finger pinion 142, and the telescopic finger rack 144 are illustrated in FIG. 2.(Finger Portion 110 Included in Gripper 100)The finger portion 110 included in the gripper 100 is a member corresponding to a human finger to be metaphorically expressed. In robotics, parts such as the finger portion 110 are sometimes also referred to as "nails.". The size, shape, and material of the finger portion 110 may be selected depending on the intended use, particularly the physical properties of the target. In FIGS. 1 and 2, two finger portions 110 are illustrated, but the disclosed technology is not limited thereto. The gripper 100 according to the disclosed technology may include three or more finger portions 110.(Rotary fingertip 120 contained in gripper 100)The rotary fingertip 120 included in the gripper 100 is a member provided at the tip of the finger portion 110 and directly comes into contact with the target. The gripper 100 according to the disclosed technology can rotate the rotary fingertip 120 because it is provided with the rotary motor 130 and the rotary gears 132. The rotation motor 130 and the rotating gears 132 will be described later (see FIG. 3 ). The rotational action of the rotational fingertip 120 may be used to carry a cable Ca that is gripped and to change the position posture of the target as a preparation operation before gripping. The operation of conveying the gripped cable Ca is an operation that presupposes a process of connecting the cable Ca to a terminal (sometimes also referred to as a "connector connection operation"). In this specification, when a certain object is referred to, i.e., when it is emphasized that the substantive is a self name, a code is appended after the name, such as "Ca" in "cable Ca", to distinguish it from an ordinary substantive. Also, in this specification, it is assumed that the cable Ca is a flexible flat cable concretely. The size and material of the rotary fingertip 120 may be designed according to the physical properties of the target. The rotary fingertip 120 may be made of, for example, silicone.(Rotation motor 130 included in gripper 100)The rotation motor 130 included in the gripper 100 is a member serving as a rotation force generator for the rotation fingertip 120. FIG. 3 is an enlarged view showing a part of the configuration of the gripper 100 according to Embodiment 1. FIG. 3 shows the rotary motor 130 and the rotary gears 132. The rotating gears 132 will be described later. The rotary fingertip 120 is connected to the rotary motor 130 via the rotary gears 132.(Rotating Gears 132 Included in Gripper 100)The rotating gears 132 included in the gripper 100 are components consisting of a plurality of gears. The rotating gears 132 have the function of regulating the torque and the speed at which the rotating fingertip 120 rotates. The gear ratio of the rotating gears 132 may be designed according to the characteristics of the rotating motor 130 and the physical characteristics of the target.(Telescopic Finger Motor 140 Included in Gripper 100)The gripper 100 according to the disclosed technology may operate its finger as if the finger became longer or shorter. The telescopic finger motor 140 included in the gripper 100 is, pictorially speaking, a member that serves as a force generator and moves the rotary fingertip 120 in the direction in which the finger becomes longer or shorter. Here, although it is not necessary that the finger portion 110 is actually extended and retracted, the direction in which the finger becomes longer or shorter is referred to as "the direction in which the finger portion 110 is extended or retracted". However, when the finger portion 110 is considered to be a member having the rotary fingertip 120 as a whole, the finger portion 110 becomes longer or shorter. As illustrated in FIGS. 1 and 2, the telescopic finger motor 140 moves the rotary fingertip 120, the rotary motor 130, and the rotary gears 132 in the direction in which the finger portion 110 is extended or retracted by using the telescopic finger pinion 142 and the telescopic finger rack 142. The telescopic finger pinion 142 and the telescopic finger rack 142 will be described later.(Telescoping finger pinion 142 and telescoping finger rack 144 included in gripper 100)The telescopic finger pinion 142 and the telescopic finger rack 144 included in the gripper 100 are mechanisms for converting the rotational force of the telescopic finger motor 140 into a linear movement. As the name suggests, the telescopic finger pinion 142 is a pinion and the telescopic finger rack 144 is a rack. The telescopic finger motor 140, the telescopic finger pinion 142, and the telescopic finger rack 144 implement the linear movement of the rotary fingertip 120, the rotary motor 130, and the gears 132.FIG. 4 is a flowchart showing the control flow of a gripper 100 according to Embodiment 1. As illustrated in FIG. 4, the control flow of the gripper 100 includes the steps of pressing the cable Ca by the rotary fingertip 120 (ST 1), image processing of the cable Ca (ST 2), calculation of the position posture of the cable Ca (ST 3), calculation of the gripping angle difference (Δθ) of the cable Ca (ST 4), the process of rotating the cable Ca (ST 5), and the process of gripping the cable Ca (ST 6).Although not shown in the figure, the control of the gripper 100 is fulfilled by a control unit. The control unit is configured in particular by a processing circuit. It can be determined that each processing step (ST 1 to ST 6) of the flowchart illustrated in FIG. 4 indicates the processing step of the control unit.Pressing of the cable Ca by the rotary fingertip 120 (ST 1) can be satisfied by so-called "pressing control". The push control is known in the art of motor control as a control that combines torque control and speed control and that can suppress the instantaneous speed increase occurring in switching from the previous position control to the torque control.The image processing of the cable Ca (ST 2) is a processing step when the control of the looper 100 is performed based on a real-time image obtained from a camera. Although not illustrated, the disclosed technology can perform the control of the gripper 100 in this manner using a camera image. A method of controlling the robot, in which the image information obtained from a camera is first processed and then the result of the image processing is fed back, is sometimes referred to as image feedback control.The calculation of the position posture of the cable Ca (ST 3) is a processing step for calculating the position posture of the cable Ca. The result calculated in this step is the information used for the image feedback control. The position posture of cable Ca to express it in the terminology of modern control theory may be referred to as the state of the control object to be observed by the control unit. Strictly speaking, the control object of the control unit is directly the gripper 100, but also the cable Ca gripped by the gripper 100 can be indirectly regarded as a control object.The calculation of the grip angle difference (Δθ) of the cable Ca (ST 4) is a processing step for calculating the grip angle difference (Δθ) of the cable Ca. The grip angle difference (Δθ) is the information used in the image feedback control.FIGS. 5A and 5B are explanatory diagrams showing an example of the controlled gripper 100 according to Embodiment 1. FIG. 5A shows a camera image at the present time. The position posture of the cable Ca at the present time is seen in FIG. 5A. FIG. 5B shows the targeted position posture of the cable Ca. That is, in the example shown in FIGS. 5A and 5B, the targeted position posture of the cable Ca is such that the longitudinal direction of the cable Ca coincides with the vertical direction of the camera image as shown in FIG. 5B. The grip angle difference (Δθ) of the cable Ca is defined as the difference between the current state and the target state, as illustrated in FIG. 5A.In the control area, the desired state is often subtracted from the current state and the difference is defined as the new state variable. In particular, in non-linear systems, a process referred to as "linearization about the equilibrium point" or "linearization about the equilibrium state" is a common means. Also in the linearization around the steady state, the error obtained by subtracting the target state (steady state) from the current state is set as a new state quantity.Note that the grip angle difference (Δθ) of the cable Ca does not reflect all errors resulting from subtraction of the target state from the current state. For example, assuming that the cable Ca is a rigid body having six degrees of freedom in a three-dimensional space, it can be considered that there are five other states besides the grip angle (θ) that can be derived directly from the camera image. In this specification, the grip angle difference (Δθ) of the cable Ca is simply given as the most dominant state quantity. In practice, other state variables are used, such as position-related variables and other angle-related variables.The process of rotating the cable Ca (ST 5) together with the pressing of the cable Ca by the rotation fingertip 120 (ST 1) is a process step of achieving the "pressing and rotating operation" of the gripper 100 according to Embodiment 1.FIGS. 6A, 6B, and 6C are explanatory diagrams 1 showing the "press-and-rotate operation" which is a technical feature of the gripper 100 according to the disclosed technology. FIG. 6A shows the gripper 100 when the control unit pushes the cable Ca with the rotary fingertip 120 (ST 1). The pressing and rotating operation against the cable Ca may be performed by a rotating fingertip 120 selected from the plurality of rotating fingertips 120, as shown in FIG. 6A. FIG. 6B shows the gripper 100 when the control unit executes a process of rotating the cable CA (ST 5). At this point, the rotary fingertip 120 rotates the cable Ca so that the grip angle difference (Δθ) becomes 0 (zero). FIG. 6C shows the gripper 100 when the control unit executes a process of gripping the cable CA (ST 6) to be described later.FIG. 7 is an explanatory diagram 2 showing the "press-and-rotate operation", which is a technical feature of the gripper 100 according to the disclosed technology. As described above, since the technology of the present disclosure includes the telescopic finger motor 140, the telescopic finger pinion 142, and the telescopic finger rack 144, the rotary fingertip 120 is movable in the direction in which the finger portion 110 is extended or retracted. In FIGS. 1 and 2, the rotary fingertips 120 are retracted from the tip of the fingertip. However, in Figs. 6A to 6C and 7, the rotary fingertip 120 is positioned at the tip of the finger in performing the "push-and-rotate" operation.In FIGS. 6A to 6C and 7, instead of the rotary fingertips 120 according to Embodiment 1, there are shown suction cup-like rotary fingertips 120B according to Embodiment 2. Details of the suction cup-like rotary fingertip 120B will be explained in Embodiment 2.A process of gripping the cable Ca (ST 6) is a processing step to perform the main operation of the gripper 100. Note that FIG. 6C shows a mode in which the finger portion 110 holds the so-called edges of the cable Ca, but the technology of the present disclosure is not limited thereto. The gripper 100 according to the disclosed technology may be controlled to grip the so-called top and bottom of the cable Ca as a human holds a ticket.Since the gripper 100 according to Embodiment 1 has the above-described configuration as described above, it is possible to satisfy the push-and-rotate operation that is the preparation operation before gripping and therefore enables the transition to gripping the target without releasing the inverse kinematics or checking the disturbance.The gripper 100 according to the disclosed technology may be separately provided with means for assisting the gripping of the target, such as an electromagnetic portion (not shown) or a suction cup (not shown). In order to grip a plurality of targets, the means that assists in gripping the target is preferably based on a mechanism other than the mechanism by which the gripper 100 grips the target. Provision of an electromagnetic portion is effective when the target has the property of adhering to the magnet. The gripping mechanism of the electromagnetic portion is a magnetic force different from the mechanism with which the gripper 100 grips the target. The gripping mechanism of the suction cup is the differential pressure to air pressure generated by the suction of air, which is different from the mechanism by which the gripper 100 grips the target.The suction cup-like rotary fingertip 120B having both the function of the rotary fingertip 120 and the function of the suction cup is shown in Embodiment 2.Embodiment 2.A gripper 100 according to Embodiment 2 is a modified version of the gripper 100 according to the technology disclosed herein. Unless otherwise specified, the same reference numerals as in Embodiment 1 are used in Embodiment 2. Also in Embodiment 2, explanations overlapping with those in Embodiment 1 are omitted as appropriate.A unique feature of the gripper 100 according to Embodiment 2 is the provision of a suction cup-like rotary fingertip 120B. The suction cup-like rotary fingertip 120B is a member having both a function as a rotating body (grip roller) and a function as a suction cup. As shown in Figs. 6A to 6C and 7, the suction cup-like rotary fingertip 120B is connected to one end of an air tube 150 which supplies the sucked air to function as a suction cup. It is not shown in the figure, but the other end of the air hose 150 is connected to an air pump.FIGS. 6A to 6C and 7 show a version in which the suction cup-like rotary fingertip 120B is provided instead of the rotary fingertip 120, but the technology disclosed herein is not limited to this version. The gripper 100 according to the technology of the present disclosure may be configured to have both the rotation fingertips 120 and the suction cup-like rotation fingertip 120B.FIG. 8 is an explanatory diagram 1 showing an operation example of the gripper 100 according to Embodiment 2. As shown in FIG. 8, the gripper 100 according to the technology disclosed herein may have the twisting fingertips 120 at the tip of the finger portion 110, and may further have the suction cup-like twisting fingertip 120B separately. In this case, the pressing and rotating operation is performed by the suction cup-like rotating fingertip 120B. When provided separately with the suction cup-like rotating fingertip 120B, the gripper 100 according to the disclosed technology includes an up-and-down movement mechanism (not shown) and a rotation mechanism (not shown) of the suction cup-like rotating fingertip 120B, regardless of the mechanism that drives the rotating fingertip 120.When the suction cup-like twisting fingertip 120B is provided adjacent to the twisting fingertips 120, the suction cup-like twisting fingertip 120B is preferably positioned at an equal distance from the two twisting fingertips 120, as shown in FIG. 8. By disposing the suction cup-like twisting fingertip 120B at such a position, it becomes easier for the two twisting fingertips 120 to grasp the cable Ca whose position posture has been adjusted by the pressing and rotating operation.When the suction cup-like twisting fingertip 120B is provided next to the twisting fingertips 120, the gripper 100 according to the technology of the present disclosure does not need to fix the suction cup-like twisting fingertip 120B. The suction cup-like rotary fingertip 120B may have a degree of freedom.FIG. 9 is an explanatory diagram 2 showing an example of an operation of the gripper 100 according to Embodiment 2. The suction cup-like twisting fingertip 120B shown in FIG. 9 can be driven in parallel with a line connecting the two twisting fingertips 120. As shown in the right diagram of FIG. 9, the drivable portion of the suction cup-like twisting fingertip 120B should preferably include a position that is the same among both of the two twisting fingertips 120. By adjusting the drivable range in this manner, the two twisting fingertips 120 are facilitated in gripping of the cable Ca whose position posture has been adjusted by the pressing and rotating operation.FIG. 10 is an explanatory diagram showing a structural example that simultaneously achieves the functions of suction and rotation of the suction cup-like rotary fingertip 120B included in the gripper 100 according to Embodiment 2. As illustrated in FIG. 10, the gripper 100 according to Embodiment 2 may include, in addition to the rotation motor 130 and the rotating gears 132, the air hose 150, a bearing 160, and a connecting body 170. The structure including the bearing 160 and the connecting body 170 enables the air to be sucked through the air hose 150 without leaking air, and at the same time, the rotational force of the rotary motor 130 can be transmitted.Since the gripper 100 according to Embodiment 2 is configured as described above, it is possible to satisfy the press-and-rotate operation that is the preparation operation before gripping without the need to release the inverse kinematics or perform a disturbance check, and therefore enables the transition to gripping the target without releasing the inverse kinematics or checking the disturbance, just like the gripper 100 according to Embodiment 1.INDUSTRIAL APPLICABILITYThe technology disclosed herein can be applied to, for example, a robot that automates cable attachment work, and is therefore industrially applicable.LIST OF REFERENCE CHARACTERS100 Gripper, 110 finger portion, 120 rotary fingertip, 120B suction cup-like rotary fingertip, 130 rotation motor, 132 rotating gears, 140 telescopic finger motor, 142 telescopic finger pinion, 144 telescopic finger rack, 150 air hose, 160 bearing, 170 connecting body.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedWO 2022 / 091246 A1

[0004]

Claims

A gripper comprising: a finger portion; a rotary fingertip provided at a tip of the finger portion to directly contact a target; a rotary motor serving as a rotary force generator for the rotary fingertip; and a telescopic finger motor serving as a force generator that moves the rotary fingertip in a direction in which the finger portion is extended or retracted, wherein the rotary fingertip performs a press-and-rotate operation on the target as a preparation operation before the gripping.The gripper of claim 1, further comprising: a set of rotating gears for adjusting torque and speed at which the rotary fingertip rotates; and a telescoping finger pinion and a telescoping finger rack that convert the rotational force of the telescoping finger motor into a linear motion.A gripper comprising: a finger portion; a suction cup-like rotating fingertip provided at a tip of the finger portion to directly contact a target; a rotation motor serving as a rotation force generator for the suction cup-like rotating fingertip; a set of rotating gears for adjusting torque and speed at which the suction cup-like rotating fingertip rotates; an air hose supplying sucked air; a bearing and a connecting body simultaneously achieving a suction function and a rotation function of the suction cup-like rotating fingertip, wherein the suction cup-like rotating fingertip performs a press-and-rotate operation on the target as a preparation operation before the gripping.

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