Gripping device

Abstract

The purpose of the present disclosure is to provide a gripping device that enables a finger part to be more compact.　This gripping device includes: a body part; a plurality of finger parts that are provided to the body part; a drive device that is provided to the body part and drives the plurality of finger parts so that the same come close to and separate from each other; a displacement sensor that detects the amount of elastic deformation of the finger parts or the drive device due to an external force received from an object to be gripped; and a control device that calculates the external force on the basis of the amount of elastic deformation and drives the drive device on the basis of the external force.

Description

gripping device

[0001] The present disclosure relates to a gripping device that is attached to the tip of a robot arm or the like.

[0002] A gripping device that grips an object to be gripped with multiple fingers that can approach and separate from each other is provided at the tip of a robot arm, etc., and is used in various fields such as manufacturing sites. It is known that the gripping device is provided with a force sensor to grip the object to be gripped with an appropriate force, and the drive of the fingers is controlled based on the detected value.

[0003] 8 shows an example of a conventional gripping device having a force sensor (Patent Document 1). The gripping device 210 has a main body 211 attached to the tip of a robot arm or the like, and a pair of fingers 212 provided on the main body 211.

[0004] The finger portion 212 has a fingertip portion 213 whose gripping surface 214 comes into contact with the object to be gripped, a base portion 215 that supports the fingertip portion 213, and a slide portion 217 that supports the base portion 215 and is movable in the left-right direction in the figure by a linear slider (not shown) provided on the main body portion 211 and is driven by a drive device (not shown) built into the main body portion 211. The force sensor 216 is provided between the fingertip portion 213 and the base portion 215.

[0005] The drive device drives the slide portion 217 to close the pair of fingers 212, allowing the object to be grasped to be grasped by the grasping surface 214 of the fingertip portion 213. At this time, a load (gripping force) from the object to be grasped is applied to the fingertip portion 213, and the magnitude of the load is detected by the force sensor 216. Then, the drive device is controlled based on the detected load to grasp the object to be grasped with a predetermined force.

[0006] Japanese Patent Application Laid-Open No. 2023-151157

[0007] When a force sensor is mounted on a finger, the size of the finger increases, which may make it difficult to insert the finger into a narrow environment.

[0008] An object of the present disclosure is to provide a gripping device that can make the finger portions compact.

[0009] The gripping device of the present disclosure includes a main body, a plurality of finger portions provided on the main body, a drive unit provided on the main body for driving the plurality of finger portions to move toward and away from each other, a displacement sensor for detecting the amount of elastic deformation of the finger portions or the drive unit due to an external force received from an object to be gripped, and a control unit for calculating the external force based on the amount of elastic deformation and driving the drive unit based on the external force.

[0010] According to the gripping device of the present disclosure, the finger portion can be made compact because no force sensor is provided between the fingertip portion and the base of the finger.

[0011] FIG. 1 is a diagram showing a gripping device of a first embodiment; FIG. 2 is a diagram showing a gripping device of a second embodiment; FIG. 3 is a diagram showing a gripping device of a third embodiment; FIG. 4 is a diagram showing a gripping device of a fourth embodiment; FIG. 5 is a diagram showing a gripping device of a fifth embodiment; FIG. 6 is a diagram showing a gripping device of a sixth embodiment; FIG. 7 is a diagram showing a gripping device of a seventh embodiment; FIG. 8 is a diagram showing a conventional gripping device;

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the components, the arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not recited in independent claims will be described as optional components.

[0013] Furthermore, each drawing is a schematic diagram and is not necessarily an exact illustration. In each drawing, the same reference numerals are used to denote substantially the same components, and redundant explanations may be omitted or simplified.

[0014] 1 is a diagram illustrating a first embodiment of the present disclosure. The gripping device 1 is attached to the tip of a robot arm or the like and can be used for tasks such as gripping and transporting a gripping target or assembling the gripping target to another object.

[0015] The gripping device 1 has a main body 2 attached to the tip of a robot arm, a plurality of fingers 3 (a pair in this example) provided on the main body 2 that move toward and away from each other, and a drive unit 4 that drives the finger parts 3 to move.

[0016] The finger portion 3 has a slide portion (driven portion) 5 that is movable along a linear guide (not shown) that is provided on the main body portion 2, a finger base portion 8 that is movable relative to the slide portion 5 via a linear guide 6 and a slider 7, and a fingertip portion 9 that is provided on the finger base portion 8. In addition, a protrusion 10 is formed on the slide portion 5 and is provided at a predetermined distance from the finger base portion 8, and the finger base portion 8 and the protrusion portion 10 are connected by an elastic member (elastic deformation portion) 11 such as a coil spring that can expand and contract.

[0017] The protrusion 10 is provided with a displacement sensor 12, which measures the distance to an end member 13 provided at the base of the finger 8. Any sensor, such as an optical sensor, can be used as the displacement sensor 12 as long as it can measure the distance to the end member 13.

[0018] The main body 2 is provided with a drive unit 4 that moves the fingers 3 along a linear guide (not shown) (only the drive unit 4 that drives the left finger unit 3 is shown in FIG. 1 , and the drive unit that drives the right finger unit 3 is not shown). The drive unit 4 is controlled by a control unit (not shown).

[0019] The drive device 4 has a pulley 50 that is rotationally driven by a motor (not shown), a belt 51 wound around the pulley 50, a clamp portion 52 that grips the belt 51, and a connecting portion 53 that connects the slide portion 5 and the clamp portion 52. The configuration of the drive device 4 is not limited to the above structure as long as it can move the slide portion 5 along the linear guide.

[0020] Next, the operation of the gripping device 1 will be described. The control device controls the drive devices 4 of the pair of fingers 3 to move the slide units 5 away from each other, widening the gap between the fingertips 9, and in this state, the gripping device 1 is moved by a robot arm or the like so that the object to be gripped is positioned between the fingertips 9. Next, the control device controls the drive devices 4 to move the slide units 5 so that the fingertips 9 approach each other, bringing the fingertips 9 into contact with the object to be gripped.

[0021] Furthermore, the control device controls the drive unit 4 to drive the slide units 5 so that the fingertip units 9 grip the object to be gripped with a predetermined gripping force. At this time, the fingertip units 9 are in contact with the object to be gripped, and therefore receive a reaction force from the object to be gripped in response to the driving force (gripping force) from the drive unit 4. That is, the finger units 3 are subjected to a driving force from the drive unit 4 in a direction that causes the fingertip units 9 to close, and an opposite reaction force (reaction) from the object to be gripped in response to this driving force, and this force causes the finger bases 8 and protrusions 10 to contract the elastic member 11 and move relatively closer to each other.

[0022] The control device acquires the distance from the displacement sensor 12 to the end member 13, calculates the amount of deformation from the distance between the displacement sensor 12 and the end member 13 when the elastic member 11 is in a neutral state, and calculates the reaction force from the object to be grasped, i.e., the gripping force, from this amount of deformation and the elastic coefficient (Young's modulus) of the elastic member 11. The control device then controls the drive device 4 so that the gripping force becomes a predetermined value.

[0023] According to this embodiment, the finger portion is made compact, and the elastic deformation portion of the finger portion 3 is deformed by the reaction force when the object to be grasped is grasped, and the grasping force can be accurately calculated based on the amount of deformation at that time.

[0024] Second Embodiment Fig. 2 is a diagram showing a second embodiment of the present disclosure. Note that the drive device is not shown in Fig. 2. In this embodiment, the finger base 8 is configured to be movable in the left-right direction of the figure relative to the slide section 5 via link members 30 and 31. The slide section 5, link members 30 and 31, and finger base 8 form a parallel link, so that the finger base 8 can move relative to the slide section 5 while maintaining its posture. The other configurations are the same as those of the first embodiment, so detailed description will be omitted.

[0025] According to this embodiment, the gripping force can be accurately calculated regardless of the mounting structure of the finger base portion 8 relative to the sliding portion 5.

[0026] (Third embodiment) Figure 3 is a diagram showing a third embodiment of the present disclosure. Note that the drive device is not shown in Figure 3. In this embodiment, the base of the finger 8 is provided so as to be movable in the left-right direction in the figure along a linear guide 14 provided on the main body 2 via a slider 15. In addition, the linear guide 14 is provided with a protrusion 10 so as to be movable in the left-right direction in the figure via a slider (driven part) 42.

[0027] The slider 42 is provided with a connecting portion 43 (only the left connecting portion 43 is shown in the figure, and the connecting portion for the finger portion 3 on the right side is omitted), and is connected to a driving device (not shown). When driven by the driving device, the slider 42 is driven in the left-right direction in the figure via the connecting portion 43. In addition, the finger base portion 8 and the protrusion portion 10 are connected by an elastic member 11.

[0028] When the slider 42 is moved left and right by the drive device, the finger base 8 is moved left and right via the elastic member 11, allowing the fingertip 9 to grasp an object to be grasped. The other configurations are the same as those of the first embodiment, so detailed description will be omitted.

[0029] According to this embodiment, the external force acting on the finger portion 3 can be measured accurately.

[0030] (Fourth embodiment) Fig. 4 is a diagram showing a fourth embodiment of the present disclosure. Note that Fig. 4 shows only the drive unit 4 that drives the left finger unit 3, and the drive unit that drives the right finger unit 3 is not shown. In this embodiment, the force applied to the drive unit 4 due to the reaction force from the object to be grasped is measured. The finger bases 8 are provided so as to be movable in the left-right direction of the figure along linear guides 14 via sliders 15.

[0031] The drive device 4 has a motor 16, an elastic coupling (elastically deformable portion) 17 connected to an output shaft 24 of the motor 16, a sliding screw 18 connected to the coupling 17, a nut 20 that moves in the axial direction of the sliding screw 18 as the sliding screw 18 rotates, and a connecting portion 21 that connects the nut 20 to the slider 15. The coupling 17, sliding screw 18, and nut 20 correspond to the transmission portion of the present disclosure. A sliding bearing 19 rotatably supports the sliding screw 18 while allowing it to move in its axial direction.

[0032] The coupling 17 has the rigidity to transmit the output of the motor 16 to the sliding screw 18, and is formed with a slit so that it is elastically deformed when subjected to an axial force from the sliding screw 18.

[0033] A tip member 22 is provided at the tip of the sliding screw 18, and a displacement sensor 23 is provided at a position spaced a predetermined distance from the tip member 22. The displacement sensor 23 can measure the distance to the tip member 22.

[0034] The driving force of the motor 16 rotates the sliding screw 18 via the coupling 17, and the rotation of the sliding screw 18 moves the nut 20 left and right in the figure. The movement of the nut 20 moves the slider 15 via the connecting part 21, and further the fingertip part 9 opens and closes left and right. In other words, the driving force of the motor 16 is transmitted to the fingertip part 9 along the drive path 80 shown by the arrow.

[0035] When the fingertip 9 comes into contact with the object to be grasped, the reaction force from the object is transmitted along the drive path 80 in the opposite direction from the fingertip 9 through the base of the finger 8, slider 15, connecting portion 21, and nut 20 to the sliding screw 18, which is displaced to the left in the figure against the elastic force of the coupling 17. The displacement sensor 23 detects the displacement of the tip member 22, and the reaction force can be calculated based on the amount of deformation of the coupling 17 and the elastic coefficient of the coupling 17.

[0036] According to this embodiment, it is possible to accurately measure the external force acting on the finger 3. Furthermore, by configuring the force detection unit within the drive path 80, a separate force sensor is not required, and the drive unit and force detection unit are integrated, which makes it possible to make the finger smaller and thinner without interfering with the drive of the robot hand or the like, thereby realizing space-saving and lightweight design, and enabling accurate measurement of the external force acting on the finger at low cost.

[0037] Fifth Embodiment FIG. 5 is a diagram illustrating a fifth embodiment of the present disclosure. Note that FIG. 5 only illustrates the drive unit 4 that drives the left finger unit 3, and the drive unit that drives the right finger unit 3 is not illustrated. In this embodiment, the arrangement of the motor 16 relative to the sliding screw 18 and the coupling 17 differs from that of the fourth embodiment. A transmission shaft 28 to which a spur gear 26 is fixed is connected to the coupling 17 on the side opposite the sliding screw 18, and the transmission shaft 28 is rotatably supported by a ball bearing 27 but immovable in the axial direction. Furthermore, a spur gear 25 is provided on the output shaft 24 of the motor 16, and is engaged with the spur gear 26. The motor 16 is disposed on the same side (left side in the figure) as the sliding screw 18 relative to the spur gears 25 and 26. Other configurations are similar to those of the fourth embodiment, and therefore detailed description thereof will be omitted.

[0038] According to this embodiment, the length of the main body 2 in the left-right direction can be made shorter than that of the gripping device 1 of the fourth embodiment, and the gripping device 1 can be made compact while accurately measuring the external force acting on the finger 3. Furthermore, by configuring the force detection unit within the drive path 80, a separate force sensor is not required, and the drive unit and force detection unit are integrated, making it possible to make the finger smaller and thinner without interfering with the drive of a robot hand or the like, thereby realizing space-saving and lightweight design, and enabling accurate measurement of the external force acting on the finger at low cost.

[0039] (Sixth Embodiment) Fig. 6 is a diagram illustrating a sixth embodiment of the present disclosure. Note that Fig. 6 only shows the drive unit 4 that drives the left finger unit 3, and the drive unit that drives the right finger unit 3 is not shown. In this embodiment, a linear guide 35 is provided on the main body 2, and a support member 33 is provided so as to be movable in the left-right direction in the figure along the linear guide 35 via a slider 36. Both left and right ends of the support member 33 are biased against the main body 2 via elastic members 34, and the support member 33 is positioned at a predetermined position.

[0040] The motor 16 is fixed on a support member 33. The sliding screw 18 is rotatably supported on the support member 33 by a ball bearing 27 so as to be immovable in its axial direction.

[0041] The main body 2 is provided with a displacement sensor 37 that measures the distance to the end of the support member 33 .

[0042] With this configuration, the fingers 3 move left and right in the figure as a result of the rotational drive of the motor 16. When the fingertip 9 comes into contact with an object to be grasped and the motor 16 is further driven in the direction of closing the fingers, the fingertip that has come into contact with the object to be grasped cannot move rightward, so the sliding screw 18 moves leftward due to the reaction force from the object to be grasped. When the sliding screw 18 moves leftward, the support member 33 that supports the sliding screw 18 by the ball bearing 27 also moves leftward against the elastic force of the elastic member 34.

[0043] The amount of deformation of the elastic member 34 due to the movement of the support member 33 is detected by the displacement sensor 37, and the reaction force from the object to be grasped is calculated from this amount of deformation and the elastic coefficient of the elastic member 34. In other words, the amount of deformation corresponds to the amount by which the drive device has moved from the predetermined position. Since the other configurations are the same as those of the fourth embodiment, detailed description will be omitted.

[0044] According to this embodiment, the external force acting on the finger unit 3 can be accurately measured while keeping the finger unit 3 compact, even without making part of the drive unit 4 elastically deformable. That is, by configuring the drive unit to detect displacement, a separate force sensor is not required, and the drive unit and force detection unit are integrated, making it possible to make the finger unit smaller and thinner without interfering with the driving of a robot hand or the like, thereby realizing space-saving and lightweight design, and enabling accurate measurement of the external force acting on the finger unit at low cost.

[0045] 7 is a diagram showing a seventh embodiment of the present disclosure. In this embodiment, the base of the finger 8 is connected to the main body 2 by link members 101 and 102, and a parallel link is formed by the main body 2, the link members 101 and 102, and the base of the finger 8. A worm wheel 116 is fixed to the main body 2 side of the link member 102.

[0046] A motor 110 is provided in the main body 2, and a spur gear 111 is fixed to the output shaft thereof. A spur gear 114 provided on a worm shaft 115 meshes with the spur gear 111. The worm shaft 115 is supported by a plain bearing 113 so as to be movable in the axial direction. The worm shaft 115 meshes with a worm wheel 116.

[0047] The worm shaft 115 is positioned by being biased at both ends by a leaf spring 120 fixed to the main body 2. A displacement sensor 121 is installed at a position spaced a predetermined distance from the leaf spring 120 and measures the distance to the leaf spring 120.

[0048] With this configuration, when not gripping an object to be gripped, the worm shaft 115 is located in a neutral position where the forces of the leaf springs 120 at both ends are balanced. The driving force of the motor 110 is transmitted through the spur gears 111 and 114, the worm shaft 115, the worm wheel 116, and the link member 102, moving the fingers 3 toward or away from each other. In other words, the driving force of the motor 110 is transmitted to the fingertips 9 along the drive path 80 indicated by the arrow.

[0049] When the fingertip 9 comes into contact with the object to be grasped due to the drive of the motor 110, the object receives a reaction force against the drive force of the motor 110. The reaction force is then transmitted in the opposite direction along the drive path 80, causing the worm shaft 115 to move in the axial direction against the biasing force of the leaf spring 120. The displacement sensor 121 detects the amount of deformation of the leaf spring 120 at this time, and the magnitude of the reaction force can be calculated from this amount of deformation and the elastic coefficient of the leaf spring 120.

[0050] According to this embodiment, even if the finger 3 is supported and driven by a parallel link, the external force acting on the finger 3 can be accurately measured. By configuring the force detection unit within the drive path 80, a separate force sensor is not required, and the drive unit and force detection unit are integrated, which makes it possible to make the finger smaller and thinner without interfering with the drive of a robot hand or the like, thereby realizing space-saving and lightweight design, and enabling accurate measurement of the external force acting on the finger at low cost.

[0051] Although the embodiments have been described above, the present disclosure is not limited to the above embodiments. The above embodiments can be implemented in any suitable combination. The number and shape of the finger portions, the structure of the drive device, the structure of the elastic deformation portion, and the like can be modified as needed.

[0052] The device can be suitably used as a gripping device in manufacturing sites, logistics sites, etc.

[0053] This application is based on Japanese Patent Application No. 2024-116855 filed on July 22, 2024, the entire contents of which are incorporated herein by reference.

[0054] REFERENCE SIGNS LIST 1 gripping device 2 main body 3 finger 4 driving device 5 sliding section 8 finger base 9 fingertip 11 elastic member 12, 23, 37, 121 displacement sensor 13 end member 16 motor 17 coupling

Claims

1. A gripping device having: a main body; a plurality of finger portions provided on the main body; a drive unit provided on the main body for driving the plurality of finger portions to move toward and away from each other; a displacement sensor for detecting an amount of elastic deformation of the finger portions or the drive unit due to an external force received from an object to be gripped; and a control unit for calculating the external force based on the amount of elastic deformation and for driving the drive unit based on the external force.

2. The gripping device according to claim 1, wherein the finger portion or the drive device has an elastically deforming portion that deforms due to the external force, and the displacement sensor detects the amount of elastic deformation of the elastically deforming portion.

3. A gripping device as described in claim 1, wherein the finger portion has a fingertip portion, a driven portion driven by the driving device, and an elastic member connecting the fingertip portion and the driven portion, and the displacement sensor detects the amount of elastic deformation of the elastic member.

4. The gripping device according to claim 1, wherein the drive unit has a drive source and a transmission unit that transmits the drive force of the drive source to the finger portion, a portion of the transmission unit being formed from an elastic member, and the displacement sensor detects the amount of elastic deformation of the elastic member.

5. The gripping device according to claim 1, wherein at least a portion of the drive device is positioned relative to the main body by an elastic member, and the displacement sensor detects the amount of elastic deformation of the elastic member.

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