Flexible bistable clamp holder for grabbing of mechanical arm

Abstract

The flexible bistable clamp holder comprises a clamp holder base, at least three sets of clamping jaws extending downwards are evenly distributed on the circumference of the clamp holder base, each clamping jaw comprises a framework driven by an electric mechanism to be bent inwards and outwards, and flexible contact plates are fixedly connected to the inner side and the outer side of each framework. On the basis of the design of a tensioning bistable soft clamping structure, the functions of rapid grabbing, stable clamping and zero-power maintaining of the gripper are achieved through the bistable characteristic, extra energy consumption is not needed during closing, and meanwhile on the basis of the material characteristic of the flexible contact plate, the rapid and stable grabbing capacity of fragile objects, fragile objects, fragile objects and fragile objects which are prone to deformation and the like is further improved.

Description

Technical Field

[0001] The invention relates to a flexible bistable clamper for mechanical arm grasping, and relates to the technical field of clampers. Background Art

[0002] With the rapid development of industrial automation and intelligent manufacturing, the robot arm has become one of the core components of the automated production line with its flexibility and high repeatability. Its technological progress and application fields are constantly expanding, and the end-gripping technology of the robot arm is more critical, which directly affects the production efficiency and operational flexibility. Although the traditional end-rigid gripping mechanism can output a large force and the motion is controllable, it lacks compliance when grasping fragile, deformable or irregular objects, which can easily cause damage or destruction to the grasped objects. In particular, rigid gripping is usually only applicable to the grasping of a single category of objects. The current flexible gripping mechanism mainly transmits external driving force through the use of flexible materials and the use of under-actuated mechanisms to transmit external driving force, thereby protecting the grasped object through deformation to achieve a certain degree of compliance. However, these methods have some disadvantages, such as the need for manual or sensor judgment of the grasping timing, which increases costs; the need for external drive to continue to act to provide clamping force after the grasping is completed; and the same force for clamping and opening the gripping device, which can easily lead to excessive force during clamping or failure to grasp the object. In response to the above problems, the present invention proposes a soft gripper based on a tensioned bistable structure, which realizes rapid grasping of the gripper through the steady-state jump characteristics of the tensioned bistable structure, and can clamp stably with zero power after grasping without additional energy consumption, thereby further improving the operating efficiency of the robotic arm. Summary of the invention

[0003] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a flexible bistable gripper for grasping by a robot arm.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a flexible bistable clamp for grasping by a robotic arm, comprising a clamp base, at least three groups of downwardly extending claws are evenly distributed on the circumference of the clamp base, and the claws include a skeleton driven by an electric mechanism to bend inwards and outwards, and flexible contact plates are fixedly connected to the inner and outer sides of the skeleton.

[0005] Preferably, the number of the clamping jaws is four groups.

[0006] Preferably, a steering gear mounting bracket is fixedly connected to the top of the clamp base.

[0007] Preferably, the electric mechanism includes a servo fixedly connected to a servo mounting bracket, the output shaft of the servo extends vertically downward and is coaxially fixedly connected to a central gear, a plurality of grooved gears are meshed on the periphery of the central gear, and the plurality of grooved gears correspond one-to-one to the clamping claws.

[0008] Preferably, a transmission mechanism mounted on the clamp base is provided between the clamping claws and the corresponding grooved gears.

[0009] Preferably, the transmission mechanism includes a vertical rotating shaft coaxially penetrated through the intermediate shaft hole of the grooved gear, the top side of the vertical rotating shaft is fixedly connected with parallel driving screws, the bottom ends of the driving screws are embedded in the circular arc grooves provided on the corresponding grooved gears; the vertical rotating shaft is coaxially fixed with a winding wheel 1 and a winding wheel 2 below the grooved gear, the winding wheel 1 is forwardly wound with an inelastic rope 1, and the winding wheel 2 is reversely wound with an inelastic rope 2, and the other ends of the inelastic rope 1 and the inelastic rope 2 extend outward to be connected with the corresponding skeleton.

[0010] Preferably, the skeleton is composed of an upper T-shaped frame, a plurality of cross-shaped frames, and a lower T-shaped frame arranged in sequence from top to bottom, the upper T-shaped frames are fixedly connected to the clamp base, the bottom of the upper T-shaped frame and the top of the cross-shaped frame, the cross-shaped frame and the cross-shaped frame, and the bottom of the cross-shaped frame and the top of the lower T-shaped frame are hinged to each other, and the upper T-shaped frame, the plurality of cross-shaped frames, and the lower T-shaped frame are fixed with a transfer rod on the inner side and the inner outer side, wherein the upper T-shaped frame and the inner side of the cross-shaped frame, the upper T-shaped frame and the outer side of the cross-shaped frame, and the cross-shaped frame are fixed with a transfer rod on the inner side and the inner outer side. Tension springs are connected between the inner side of the cross frame, between the outer side of the cross frame, between the inner side of the cross frame and the lower T-frame, and between the outer side of the cross frame and the lower T-frame. The ends of the tension springs are tied to the corresponding transfer rods via cable ties. The inelastic ropes 1 extend downward from top to bottom through the rope holes on the outer transfer rods in sequence, and are finally tied to the outer transfer rod at the bottom. The inelastic ropes 2 extend downward from top to bottom through the rope holes on the inner transfer rods in sequence, and are finally tied to the inner transfer rod at the bottom.

[0011] Preferably, the outer surface of the inner flexible contact plate is plugged and glued to the inner end side mortise and tenon of the upper T-frame, several cross-frames and lower T-frame, and the inner surface of the outer flexible contact plate is plugged and glued to the outer end side mortise and tenon of the upper T-frame, several cross-frames and lower T-frame.

[0012] Preferably, the top end of the upper T-shaped frame is fixedly connected with a rope winding frame, and the rope winding frame is provided with a guide wheel for guiding and reversing the inelastic ropes one and two.

[0013] Preferably, a plurality of cylindrical long strip protrusions are fixedly provided on the surface of the flexible contact plate for contacting and grasping the object, so as to increase the friction force with the grasped object.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Based on the design of the tensioned bistable soft clamping structure, the bistable characteristics enable the clamp to quickly grasp, stably clamp, and maintain zero power. No additional energy consumption is required when closing. Based on the material properties of the flexible contact plate, it can be used for fast and stable grasping of fragile objects. Its structural feature is that the flexible contact plate made of flexible silicone material is used to envelop the grasped object. Compared with traditional rigid components, it has higher flexibility and better protection performance. At the same time, the contact surface adopts cylindrical long strip protrusions, which increases the contact friction with the grasped object and improves stability.

[0015] 2. In the intermediate transition state of the present invention, the clamp unit is in a balanced unstable state, the tension spring and the flexible contact plate are pre-stretched, and in the two states of the clamp being opened and closed, the tension springs and the flexible contact plates on the inner and outer sides switch between maximum and minimum stretching, and no additional holding force is required in the open and closed states; by changing the pre-tightening force of the tension spring, the flexible contact plate and the size parameters of the skeleton, the potential energy barrier difference of the tension bistable state jump can be adjusted; a servo is used as the driving source, and the transmission is carried out through the gear-guide wheel-inelastic rope to control the change in the length of the inelastic rope, thereby realizing the opening and closing of the clamp, and effectively reducing the complexity of the drive-transmission.

[0016] 3. The present invention is driven by a steering gear, and the gear transmission drives the inelastic ropes one and two to realize the switching of the clamp unit between the open and closed states. It has the advantages of simple driving mode, easy to trigger closure, stable clamping, and zero power maintenance, so that the flexible tension bistable clamp can realize the grasping function of fragile objects.

[0017] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a stereogram of an embodiment of the present invention.

[0019] Figure 2 FIG. 4 is a top view of an embodiment of the present invention.

[0020] Figure 3 It is a front view of an embodiment of the present invention.

[0021] Figure 4 It is a schematic diagram of the partial structure of the electric mechanism.

[0022] Figure 5 It is a schematic diagram of the partial structure of the transmission mechanism.

[0023] Figure 6 Schematic diagram of the motion principle of an embodiment of the present invention.

[0024] Figure 7 It is a schematic diagram of an intermediate equilibrium unstable state of an embodiment of the present invention.

[0025] Figure 8 Schematic diagram of the silicone casting mold for the flexible contact plate.

[0026] Fig. 9 It is a schematic diagram of an embodiment of the present invention installed on a robotic arm.

[0027] In the figure: clamp base 1, clamping claw 2, flexible contact plate 3, steering gear mounting bracket 4, steering gear 5, central gear 6, grooved gear 7, vertical shaft 8, winding wheel one 9, winding wheel two 10, inelastic rope one 11, inelastic rope two 12, upper T-frame 13, cross frame 14, lower T-frame 15, adapter rod 16, tension spring 17, rope threading hole 18, rope winding frame 19, guide wheel 20, mechanical arm 21, upper mold 22, lower mold 23, plug screw 24, arc groove 25. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] like Figures 1 to 9 As shown, this embodiment provides a flexible bistable gripper for grasping by a robotic arm, including a gripper base 1, on which at least three groups of downwardly extending jaws 2 are evenly distributed on the circumference, and the jaws each include a skeleton driven by an electric mechanism to bend inwards and outwards, and flexible contact plates 3 are fixedly connected to the inner and outer sides of the skeleton.

[0032] In the embodiment of the present invention, the number of the clamping jaws is four groups.

[0033] In the embodiment of the present invention, a steering gear mounting bracket 4 is fixedly connected to the top of the clamp base.

[0034] In the embodiment of the present invention, the electric mechanism includes a servo 5 fixedly connected to a servo mounting bracket, the output shaft of the servo extends vertically downward and is coaxially fixedly connected to a center gear 6, the periphery of the center gear is meshed with a plurality of grooved gears 7, and the plurality of grooved gears correspond one-to-one to the clamping claws.

[0035] In the embodiment of the present invention, a transmission mechanism installed on the clamper base is provided between the clamping claws and the corresponding grooved gears.

[0036] In the embodiments of the present invention, the transmission mechanism comprises a vertical rotating shaft 8 coaxially penetrated through the intermediate shaft hole of the grooved gear, the top side of the vertical rotating shaft is fixedly connected with mutually parallel plug screws 24, the bottom ends of the plug screws are embedded in the circular arc grooves 25 provided on the corresponding grooved gears; the vertical rotating shaft is coaxially fixed with a winding wheel 1 9 and a winding wheel 2 10 below the grooved gears, the winding wheel 1 is forwardly wound with an inelastic rope 1 11, the winding wheel 2 is reversely wound with an inelastic rope 2 12, and the other ends of the inelastic rope 1 and the inelastic rope 2 extend outward to be connected with the corresponding skeleton.

[0037] The grooved gear is a gear with an arc-shaped groove extending through the end face of the involute cylindrical gear while ensuring its strength. The other structural features are the same as those of the general involute cylindrical gear. In terms of transmission, when the grooved gear is used as a driven wheel, the center gear as the driving wheel drives the grooved gear to engage and transmit. The grooved gear will first rotate a certain angle around the vertical axis. At this time, the grooved gear does not drive its vertical axis to rotate. When one end of the arc-shaped groove of the grooved gear contacts the plug screw, it begins to drive the vertical axis to rotate, and then the transmission characteristics are consistent with those of general gears.

[0038] The grooved gear is used instead of the general gear transmission because when the potential energy of the tensioned bistable structure exceeds the potential energy barrier, a jump will occur. The jump speed is fast and the servo will limit the rotation of the ordinary gear. Therefore, it is necessary to reserve a section of empty rotation stroke to separate the servo and the grooved gear.

[0039] The inelastic rope 1 and the inelastic rope 2 are wound in opposite directions on the winding wheel 1 and the winding wheel 2, respectively. When the steering gear rotates in opposite directions, the forces on the two inelastic ropes are opposite. The steering gear rotates through the gear transmission to control the winding wheel 1 and the winding wheel 2 to control the inelastic rope 1 and the inelastic rope 2 to pull the ends of the gripper unit to generate torques in opposite directions, thereby realizing the opening and closing of the gripper for grasping objects.

[0040] In the embodiment of the present invention, the skeleton is composed of an upper T-shaped frame 13, a plurality of cross-shaped frames 14, and a lower T-shaped frame 15 arranged in sequence from top to bottom. The upper T-shaped frames are fixedly connected to the clamp base, and the bottom of the upper T-shaped frame and the top of the cross-shaped frame, the cross-shaped frame and the cross-shaped frame, and the bottom of the cross-shaped frame and the top of the lower T-shaped frame are hinged to each other. The upper T-shaped frame, the plurality of cross-shaped frames, and the lower T-shaped frame are all fixed with a transfer rod 16 on the inner side and the inner outside, wherein the upper T-shaped frame and the inner side of the cross-shaped frame, the upper T-shaped frame and the outer side of the cross-shaped frame, and the cross-shaped frame are fixed with a transfer rod 16. Tension springs 17 are connected between the frame and the inner side of the cross frame, between the cross frame and the outer side of the cross frame, between the cross frame and the inner side of the lower T-frame, and between the cross frame and the outer side of the lower T-frame. The ends of the tension springs are tied to the corresponding transfer rods via cable ties to generate pre-tightening force; the inelastic ropes 1 extend downward from top to bottom through the rope holes 18 opened on the outer transfer rod, and are finally tied to the outer transfer rod at the bottom; the inelastic ropes 2 extend downward from top to bottom through the rope holes opened on the inner transfer rod, and are finally tied to the inner transfer rod at the bottom.

[0041] The rotation of the steering gear drives the central gear to rotate, and the central gear meshes with the four grooved gears to transmit motion, and then drives the vertical shaft to rotate, so that the winding wheel 1 and the winding wheel 2 installed on the four sides of the clamp base rotate. In order to ensure that the tension of the inelastic rope 1 and the inelastic rope 2 is opposite when the steering gear rotates in the opposite direction, thereby generating opposite torques to drive the opening and closing of the clamp unit, the inelastic rope 1 and the inelastic rope 2 wound on the winding wheel 1 and the winding wheel 2 are wound in opposite directions.

[0042] In an embodiment of the present invention, the outer surface of the inner flexible contact plate is plugged into and bonded to the inner end sides of the upper T-frame, a plurality of cross-frames, and the lower T-frame through mortise and tenon joints, and the inner surface of the outer flexible contact plate is plugged into and bonded to the outer end sides of the upper T-frame, a plurality of cross-frames, and the lower T-frame through mortise and tenon joints.

[0043] The flexible contact plate is pre-stretched in the intermediate equilibrium unstable state to generate a pre-tightening force together with the tension spring to provide a bistable characteristic; in the intermediate equilibrium unstable state, the inelastic rope 1 and the inelastic rope 2 are in a critical tension state.

[0044] In the embodiment of the present invention, the top end of the upper T-shaped frame is fixedly connected with a rope winding frame 19, and the rope winding frame is provided with a guide wheel 20 for guiding and reversing the first and second inelastic ropes.

[0045] In the embodiment of the present invention, a plurality of cylindrical long strip protrusions are fixedly provided on the surface of the flexible contact plate for contacting the grasped object, so as to increase the friction force with the grasped object.

[0046] The contact surface end of the flexible contact plate has a cylindrical long strip convex structure to increase the friction between the contact surface and the clamped object. The flexible contact plate is cast from silicone in one piece through a mold, the lower mold and the upper mold are assembled and fixed with tape to prevent displacement between the two molds, and then the silicone material is introduced into the combined splicing mold, and the tape is torn off after the silicone solidifies, and the upper mold 22 is removed, and then the molded flexible contact plate is separated from the lower mold 23 to complete demoulding.

[0047] In the embodiment of the present invention, the tensioned bistable soft clamp of the present invention has two stable states, namely, an open stable state and a closed stable state. The tensioned bistable soft clamp realizes the switching of the two stable states by driving the inelastic rope 1 and the inelastic rope 2 through the forward and reverse transmission of the servo. The initial state of the clamp is the open stable state. The torque M is generated by the forward rotation of the servo to pull the inelastic rope 2 so that the clamp unit transitions from the open bending state to the closed bending state. When the servo rotates to a certain extent, it reaches the state as shown in FIG. Figure 7 The bistable equilibrium unstable state shown in the figure, at this time, the servo only needs to continue to rotate slightly at the same steering angle to trigger the bistable jump behavior, and the clamping unit jumps to a closed bending state, thereby realizing the switching of the tensioned bistable clamp from an open stable state to a closed stable state. Similarly, when in the closed state, the servo reverses, pulling the inelastic rope to generate an opposite torque M, causing the clamping unit to transition to an open bending state, thereby gradually opening the soft clamp until it reaches an open stable state.

[0048] like Fig. 9 The figure shows a schematic diagram of a robot arm that can realize flexible grasping of an object, which is composed of a robot arm 21 and a tension bistable soft gripper. The tension bistable soft gripper is installed at the end of the robot arm, and the two are connected and fastened together through holes and bolt pairs. The robot arm is precisely controlled to be positioned near the grasped object and the forward and reverse rotation of the servo is controlled to realize rapid protection grasping of fragile and fragile objects. In addition, since the jump of the bistable state needs to exceed its potential energy barrier, the tension bistable flexible gripper can also grasp objects with a certain kinetic energy.

[0049] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A flexible bistable gripper for grasping by a robotic arm, characterized in that: It comprises a clamp base, on which at least three groups of downwardly extending clamping jaws are evenly distributed circumferentially, and the clamping jaws each comprise a frame driven by an electric mechanism to bend inwards and outwards, and flexible contact plates are fixedly connected to the inner and outer sides of the frame.

2. The flexible bistable gripper for robot gripping according to claim 1, characterized in that: The number of the clamping jaws is four groups.

3. The flexible bistable gripper for robot gripping according to claim 1, characterized in that: The top of the clamp base is fixedly connected with a steering gear mounting bracket.

4. The flexible bistable gripper for robot gripping according to claim 3, characterized in that: The electric mechanism comprises a servo fixedly connected to a servo mounting bracket, wherein an output shaft of the servo extends vertically downward and is coaxially fixedly connected to a central gear, a periphery of the central gear is meshed with a plurality of grooved gears, and the plurality of grooved gears correspond one to one to the clamping claws.

5. The flexible bistable gripper for robot gripping according to claim 4, characterized in that: A transmission mechanism installed on the clamp base is arranged between the clamping claws and the corresponding grooved gears.

6. The flexible bistable gripper for robot gripping according to claim 5, characterized in that: The transmission mechanisms include a vertical rotating shaft coaxially inserted through the intermediate shaft hole of the grooved gear, the top side of the vertical rotating shaft is fixedly connected with parallel plug screws, the bottom ends of the plug screws are embedded in the circular arc grooves provided on the corresponding grooved gears; the vertical rotating shaft is coaxially fixed with a winding wheel 1 and a winding wheel 2 below the grooved gears, the winding wheel 1 is forwardly wound with an inelastic rope 1, and the winding wheel 2 is reversely wound with an inelastic rope 2, and the other ends of the inelastic rope 1 and the inelastic rope 2 extend outward to be connected with the corresponding skeleton.

7. The flexible bistable gripper for robot gripping according to claim 6, characterized in that: The skeletons are composed of an upper T-frame, a plurality of cross-frames, and a lower T-frame, which are arranged in sequence from top to bottom. The upper T-frames are fixedly connected to the clamp base. The bottom of the upper T-frame and the top of the cross-frame, the cross-frame and the cross-frame, and the bottom of the cross-frame and the top of the lower T-frame are hinged to each other. The upper T-frame, the plurality of cross-frames, and the lower T-frame are all fixed with transfer rods on the inner side and the inner side. The upper T-frame and the inner side of the cross-frame, the upper T-frame and the outer side of the cross-frame, and the cross-frame and the cross-frame are connected to each other. Tension springs are connected between the inner sides of the U-shaped frames, between the outer sides of the cross-shaped frames and the cross-shaped frames, between the inner sides of the cross-shaped frames and the lower T-shaped frames, and between the outer sides of the cross-shaped frames and the lower T-shaped frames. The ends of the tension springs are tied to the corresponding transfer rods via cable ties. The inelastic ropes 1 extend downward from top to bottom through the rope holes on the outer transfer rods in sequence, and are finally tied to the outer transfer rod at the bottom. The inelastic ropes 2 extend downward from top to bottom through the rope holes on the inner transfer rods in sequence, and are finally tied to the inner transfer rod at the bottom.

8. The flexible bistable gripper for robot gripping according to claim 7, characterized in that: The outer surface of the inner flexible contact plate is plugged and bonded with the inner end mortise and tenon of the upper T-frame, several cross-frames and the lower T-frame, and the inner surface of the outer flexible contact plate is plugged and bonded with the outer end mortise and tenon of the upper T-frame, several cross-frames and the lower T-frame.

9. The flexible bistable gripper for robot gripping according to claim 7, characterized in that: The top end of the upper T-shaped frame is fixedly connected with a rope winding frame, and the rope winding frame is provided with a guide wheel for guiding and reversing the first and second inelastic ropes.

10. The flexible bistable gripper for robot gripping according to claim 1, characterized in that: The surface of the flexible contact plate for contacting and grasping an object is provided with a plurality of cylindrical long strip protrusions for increasing the friction force with the grasped object.

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