A hybrid-driven flexible manipulator based on origami structure

Abstract

The application belongs to the technical field of soft robot, and particularly relates to a hybrid driving flexible mechanical arm based on a paper folding structure. The flexible mechanical arm adopts a modular combination structure, and comprises a gripper module and a plurality of body segment modules. Each module has a paper folding structure. The plurality of body segment modules are connected in series. Each body segment module has the deformation capability of bending in four directions and axial elongation. The gripper module is located at the end of the body segment modules connected in series, and has the capability of grasping different objects. The mechanical arm designed in the application realizes the simplification of the machining process and the lightweight of the overall structure. The modular design is convenient for adjusting the structure and function. The heating and shrinking process of the shape memory alloy spring is controlled by turning on and off the current through the circuit, which is flexible and convenient. The mechanical arm end has a large working space, and can realize rich spatial configurations. The gripper at the end of the mechanical arm has the capability of grasping objects of different sizes, different shapes and different softness, and has a wide range of adaptability.

Description

Technical Field

[0001] This invention belongs to the field of soft robot technology, specifically relating to a hybrid-driven flexible robotic arm. Background Technology

[0002] Most existing flexible robotic arms employ a single drive method, such as pneumatic, shape memory alloy, or rope drive. However, a single drive method has certain limitations. For example, pneumatic drives allow for compact robotic arm designs, but require high airtightness and control precision; shape memory alloys enable rapid contraction and deformation, but require a long cooling time; rope drives provide significant driving force, but require additional motors and devices to stretch and contract the traction rope. Therefore, a single actuator limits the operational efficiency of flexible robotic arms. Secondly, most flexible robotic arms use a centralized actuator arrangement, which also limits the degrees of freedom and overall deformation capabilities. Finally, existing flexible robotic arms are generally made of silicone or composite materials, resulting in complex manufacturing processes and heavy weight, which restricts the reachable workspace of the robotic arm.

[0003] To further improve the spatial accessibility and deformability of the flexible robotic arm, while achieving its lightweight design and simplified fabrication process, we designed this modular hybrid-driven robotic arm based on origami structure. Summary of the Invention

[0004] The purpose of this invention is to provide a hybrid-driven flexible robotic arm with rich spatial configuration and outstanding motion capabilities.

[0005] The hybrid-driven flexible robotic arm designed in this invention adopts a modular combination structure, including a gripper module and several segment modules; each module has an origami structure; the segment modules are connected in series; each segment module has bending and axial elongation deformation capabilities in four directions; the gripper module is located at the end of the series-connected segment modules and has the ability to grasp objects of different shapes and softness / hardness; therefore, the robotic arm has excellent spatial accessibility and can realize a variety of spatial configurations. Wherein:

[0006] Each segment module consists of a Yoshimura origami structure, a pneumatic module, a PCB circuit board, and a shape memory alloy spring; among which:

[0007] The PCB circuit board is divided into upper and lower parts;

[0008] The pneumatic module has at least one set, for example, one, two, three, four, etc. The two ends of the multiple sets of pneumatic modules are respectively fixedly connected to two PCB circuit boards, and the multiple sets of pneumatic modules are evenly distributed in space between the two PCB circuit boards; each pneumatic module contains a pneumatic muscle, which is controlled through the same air path and is supplied with air by an external air pump.

[0009] The Yoshimura origami structure is fixedly connected to two PCB circuit boards at both ends and spatially surrounds multiple sets of pneumatic molds.

[0010] The shape memory alloy springs are at least four, for example, four, five, or six. The two ends of the multiple shape memory alloy springs are fixedly connected to two PCB circuit boards. The multiple shape memory alloy springs are evenly distributed in space between the two PCB circuit boards and located on the outside of the Yoshimura origami structure. The heating and contraction process of the shape memory alloy springs is controlled by the circuit to control the opening and closing of the current. The segment can be elongated by inflating the pneumatic muscle. The segment can be bent on one side by heating two adjacent shape memory alloy springs while inflating the pneumatic muscle.

[0011] The grasping module consists of a Waterbomb origami structure, a slider, a slide rail, a traction rope, a shape memory alloy spring, and a PCB circuit board; wherein:

[0012] The slide rail is a cylinder, with one end fixed to the center of the PCB circuit board; the slider is a circular block with a circular hole in its center that matches the diameter of the cylindrical slide rail, and it fits onto the cylindrical slide rail and can slide up and down.

[0013] The shape memory alloy springs are at least two, for example, two, three, four, etc. The two ends of the multiple shape memory alloy springs are respectively fixedly connected to the PCB circuit board and the slider. The multiple shape memory alloy springs are evenly distributed in space between the PCB circuit board and the slider. The heating and contraction process of the shape memory alloy springs is controlled by the circuit to control the opening and closing of the current.

[0014] The Waterbomb origami structure is surrounded by a shape memory alloy spring, slider, and slide rail assembly. The front end of the Waterbomb origami is fixedly connected to the PCB circuit board. There are at least two traction ropes, such as two, three, or four ropes. One end of the traction rope is fixedly connected to the other side of the slider, and the other end is connected to the gripper finger at the front end of the Waterbomb origami.

[0015] The process is as follows: two adjacent shape memory alloy short springs are heated and contracted, shortening the distance between the slider and the PCB circuit board, causing the slider to slide along the rail towards the bottom; simultaneously, multiple traction ropes, pulled by the slider, cause the front end of the paper-folding gripper to bend inward, and the gripper module will exhibit a gripping state. When the two shape memory short springs are no longer heated, the gripper module will gradually return to its initial open state.

[0016] In the segment module:

[0017] Furthermore, the pneumatic muscle consists of an airbag, a T-shaped seal, cable ties, and PU tubing; the airbag is wrapped in a woven bag, which mainly undergoes axial deformation after inflation; one end of the airbag is sealed by a T-shaped seal and fixed to the upper PCB circuit board by cable ties; one end of the airbag is fixedly connected to the other end by PU tubing, and multiple PU tubing are connected to a manifold, the other side of which is connected to a main air supply pipe for supplying air to the airbag.

[0018] Furthermore, the two PCBs have identical hole geometry. A central circular hole allows the air tube to pass through the module's interior. Multiple mounting slots around the circular hole are used to secure the pneumatic muscles. Specifically, the T-shaped seal at the end of the pneumatic muscle can be placed horizontally into the mounting slot and then rotated 90 degrees to secure it to the PCB. The air inlet of the pneumatic muscle is secured with a locking cable tie, which latches onto the circuit board and is then secured by another horizontal cable tie. Multiple pneumatic muscles on each module are secured to the PCB in this manner. The driving air pressure range for the pneumatic muscles is 0.125 MPa to 0.225 MPa.

[0019] Furthermore, each PCB board is also designed with shape memory alloy spring mounting holes, and each shape memory alloy spring is connected to the PCB board by bolts.

[0020] Furthermore, both ends of the Yoshimura origami structure are connected to the PCB board by bolts. In order to ensure that the origami structure has a certain load-bearing capacity while having a large deformation capacity, a polyethylene terephthalate (PET) film with a thickness of 0.125mm is selected and then processed by a laser cutting machine.

[0021] Furthermore, the module PCB also includes a main control chip, a remote signal transmission chip, a circuit switch control chip, an inertial sensor, and related supporting circuits.

[0022] Furthermore, each PCB board has four circular mounting holes near its outer edge, which can be used for connections between body segment modules and between body segment modules and gripping modules.

[0023] Furthermore, the dimensions of the two PCBs should satisfy the principle that there is no interference before bending to the maximum angle.

[0024] In the crawling module:

[0025] Furthermore, the slide rail is connected to the PCB board of the gripping module by bolts.

[0026] Furthermore, the Waterbomb origami gripper structure is connected to the PCB via bolts. To ensure that the origami gripper structure has a certain gripping load-bearing capacity, a polyethylene terephthalate (PET) film with a thickness of 0.125mm is selected and then processed using a laser cutting machine.

[0027] Furthermore, one end of each traction rope is fixed to the inside of the origami gripper, and the other end is fixed to a cylindrical slider with bolts. The cylindrical slider has a circular hole in the center, allowing it to slide along the guide rail.

[0028] Furthermore, one end of the shape memory alloy short spring is fixed to the bottom of the slider with a bolt, and the other end is fixed to the gripper module PCB board with a bolt.

[0029] Compared with the prior art, the beneficial effects achieved by the present invention

[0030] (1) The robotic arm designed in this invention simplifies the processing process and reduces the overall weight: Compared with traditional flexible robotic arms that are generally made of silicone, the origami structure of the main body of this design can be quickly processed by laser cutting technology, making it very convenient to manufacture; at the same time, since the origami structure is a three-dimensional structure formed by folding thin film material, the overall weight is very light; in addition, the origami robotic arm designed in this invention is based on the modular concept, which makes it easy to adjust the structure and function.

[0031] The heating and contraction process of the shape memory alloy spring is controlled by controlling the opening and closing of the current through the circuit.

[0032] (2) The robotic arm of the present invention has excellent motion capabilities: axial deformation is achieved by pneumatic muscle inflation and elongation, which has a large bending stiffness and elongation rate; bending deformation is achieved by the simultaneous action of shape memory alloy spring heating and contraction and pneumatic muscle inflation, which has a large bending angle; in addition, both pneumatic muscles and shape memory alloy can move quickly, so the robotic arm as a whole can quickly switch configurations.

[0033] (3) This invention has wide applications: the end of the origami robot arm has a large working space, and the robot arm as a whole can achieve a variety of spatial configurations; the gripper at the end of the robot arm is capable of grasping objects of different sizes, shapes and hardness. Attached Figure Description

[0034] Figure 1This is a schematic diagram of the main structure of the hybrid-driven origami robotic arm of the present invention.

[0035] Figure 2 This is a schematic diagram of the original state of the segment module in this invention.

[0036] Figure 3 This is a schematic diagram of the structure of the segment module in the extended state in this invention.

[0037] Figure 4 This is a schematic diagram of the structure of the segment module in the bending state in this invention.

[0038] Figure 5 This is a schematic diagram of the initial state structure of the gripper module in this invention.

[0039] Figure 6 This is a schematic diagram of the gripper module's gripping state structure in this invention.

[0040] Figure 7 Schematic diagram of the spatial configuration of the origami robotic arm.

[0041] The diagram is labeled as follows: 1 is the first body segment module, 2 is the second body segment module, 3 is the third body segment module, 4 is the fourth body segment module, 5 is the gripper module, 6 is the inter-module connecting bolt, 7 is the inter-module connecting bolt, 8 is the inter-module connecting bolt, 9 is the inter-module connecting bolt, 101 is the Yoshimura origami structure, 102 is the lower PCB circuit board of the body segment, 103 is the upper PCB circuit board of the body segment, 104 is the first shape memory alloy spring, 105 is the second shape memory alloy spring, 106 is the third shape memory alloy spring, 107 is the fourth shape memory alloy spring, 108 is the first 3D printed airbag seal, 109 is the second 3D printed airbag seal, 110 is the third 3D printed airbag seal, 111 is the first airbag, 112 is the second airbag, and 113 is the third airbag. 114 is the first airbag supply tube, 115 is the second airbag supply tube, 116 is the third airbag supply tube, 117 is the upper cable tie of the first airbag, 118 is the upper cable tie of the second airbag, 119 is the upper cable tie of the third airbag, 120 is the lower cable tie of the first airbag, 121 is the lower cable tie of the second airbag, 122 is the lower cable tie of the third airbag, 123 is the 3D printed manifold, 124 is the main air supply tube, 501 is the Waterbomb origami structure, 502 is the gripper PCB circuit board, 503 is the first 3D printed slide rail, 504 is the second 3D printed slider, 505 is the first shape memory alloy short spring, 506 is the second shape memory alloy short spring, 507 is the first traction rope, 508 is the second traction rope, 509 is the third traction rope, and 510 is the fourth traction rope. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0046] (I) A paper-folding robotic arm comprising four body segment modules and one gripper module, such as Figure 1 As shown. Body segment module 1 and body segment module 2 are connected by bolts 6, 7, 8, and 9. The other body segment modules and gripper modules are also connected in the same way.

[0047] (II) Specific design of the segment modules, such as Figure 2As shown. There are four shape memory alloy springs, and three pneumatic modules are in the pneumatic module. The Yoshimura origami structure 101, the first shape memory alloy spring 104, the second shape memory alloy spring 105, the third shape memory alloy spring 106, and the fourth shape memory alloy spring 106 are mounted on the lower PCB circuit board 102 and the upper PCB circuit board 103 of the body segment. The two circuit boards also include a wireless communication module, an inertial sensor module, and a microcontroller. A schematic diagram of the creases of the Yoshimura origami structure 101 is shown below. Figure 2 As shown in (c). The specific structure of the air bladder in the pneumatic model is as follows. Figure 2 As shown in (d), one end of the first airbag 111, the second airbag 112, and the third airbag 113 are sealed with 3D-printed airbag seals 108, 109, and 110, respectively, and secured with lower airbag straps 120, 121, and 122. The other ends of the three airbags are connected to airbag supply pipes 114, 115, and 116, respectively, and secured with upper airbag straps 117, 118, and 119. The three airbags 111, 112, and 113 are also fixed to the lower PCB circuit board 102 and the upper PCB circuit board 103 of the body segment. The air supply pipes 114, 115, and 116 of each airbag are connected to a 3D-printed manifold 123, and the main air supply pipe 124 is connected to the other end of the manifold 123 for supplying air to the airbags.

[0048] like Figure 3 The diagram shows the structure of the origami robot arm's segmental module in its extended state. The first airbag 111, the second airbag 112, and the third airbag 113 are inflated through the main air supply pipe 124, causing them to extend and thus making the segmental module axially extended. When inflation of airbags 111, 112, and 113 stops, the airbags return to their original length, and the segmental module returns to its initial contracted state.

[0049] like Figure 4 The diagram shows the structural schematic of the origami robot arm's segmental module in a bent state (taking a leftward bend as an example). The first shape memory alloy spring 104 and the second shape memory alloy spring 105 are heated together and contract, simultaneously inflating the first airbag 111, the second airbag 112, and the third airbag 113, causing the segmental module to bend to the left. When the shape memory alloy springs 104 and 105 are de-energized, and the airbags 111, 112, and 113 stop inflating, the segmental module returns to its initial contracted state. To achieve bending in other directions, only the corresponding shape memory alloy spring needs to be heated.

[0050] (III) Specific design of the gripper module, such as Figure 5As shown. The Waterbomb origami structure 501 and the 3D-printed slide rail 503 are both fixed to the gripper PCB circuit board 502. The circuit board also includes a wireless communication module, an inertial sensor module, and a microcontroller. The 3D-printed slider 504 is fitted onto the 3D-printed slide rail 503. One end of the first shape memory alloy short spring 505 and the second shape memory short spring 506 are fixed to the bottom of the 3D-printed slide rail 503, and the other end is fixed to the lower part of the 3D-printed slider 504. One end of the first traction rope 507, the second traction rope 508, the third traction rope 509, and the fourth traction rope 510 are all fixed to the upper part of the 3D-printed slider 504, and the other end is fixed to the Waterbomb origami structure 501.

[0051] like Figure 6 The diagram shows the gripper module of the origami robotic arm in its gripping state. The first shape memory alloy short spring 505 and the second shape memory short spring 506 are heated and contracted, shortening the distance between the bottom of the 3D printed slider 504 and the bottom of the 3D printed guide rail 503, causing the slider to slide downwards. Simultaneously, the first traction rope 507, the second traction rope 508, the third traction rope 509, and the fourth traction rope 510, under the traction of the slider, cause the front end of the origami gripper to bend inwards, thus initiating the gripping state. When the shape memory short springs 505 and 506 are de-energized, the gripper module gradually returns to its initial open state.

[0052] Function demonstration: such as Figure 7 The diagram shows the possible configurations of the origami robot arm. Since the drive control of each segment module is independent, the robot arm has a variety of spatial configurations. Several of these configurations are listed here. (a) is a straight line configuration, where all four segments 1, 2, 3, and 4 of the robot arm are in an axially extended state; (b) is an upper bending configuration, where segment 1 of the robot arm is bent to the right, and the remaining segments 2, 3, and 4 are in an axially extended state; (c) is a 'J' curve configuration, where segments 3 and 4 of the robot arm are bent to the right, and segments 1 and 2 are in an extended state; (d) is an 'S' curve configuration, where segments 1 and 2 are bent to the right, and segments 3 and 4 are bent to the left; (e) is a 'C' curve configuration, where segments 1, 2, 3, and 4 are all bent to the right; (f) is a 3D curve configuration, where segments 1 and 2 are bent to the left, and segments 3 and 4 are bent forward.

Claims

1. A hybrid-driven flexible robotic arm based on origami structure, characterized in that, It adopts a modular assembly structure, including a grasping module and several segment modules; each module has an origami structure; several segment modules are connected in series; each segment module has the ability to bend in four directions and elongate axially; the grasping module is located at the end of the series-connected segment modules and has the ability to grasp objects of different shapes and different soft and hard materials; wherein: Each segment module consists of a Yoshimura origami structure, a pneumatic module, a PCB circuit board, and a shape memory alloy spring; wherein: The PCB circuit board is divided into upper and lower parts; The pneumatic module consists of multiple sets; both ends of the multiple sets of pneumatic modules are fixedly connected to two PCB circuit boards, and the multiple sets of pneumatic modules are evenly distributed in space between the two PCB circuit boards; each pneumatic module contains pneumatic muscles, which are controlled through the same air path and supplied with air by an external air pump. The Yoshimura origami structure is fixedly connected to two PCB circuit boards at both ends and spatially surrounds multiple sets of pneumatic molds. There are at least four shape memory alloy springs, with both ends of the springs fixedly connected to two PCB boards. The springs are evenly distributed between the two PCB boards and located on the outside of the Yoshimura origami structure. The heating and contraction process of the shape memory alloy springs is controlled by the circuit to control the opening and closing of the current. The body segment is elongated by inflating the pneumatic muscles. The body segment is bent on one side by heating two adjacent shape memory alloy springs while simultaneously inflating the pneumatic muscles. The grasping module consists of a Waterbomb origami structure, a slider, a slide rail, a traction rope, a shape memory alloy spring, and a PCB circuit board; wherein: The slide rail is a cylinder, with one end fixed to the center of the PCB circuit board; the slider is a circular block with a circular hole in its center that matches the diameter of the cylindrical slide rail, and it fits onto the cylindrical slide rail and can slide up and down. The shape memory alloy springs consist of at least two springs, with both ends of the springs fixedly connected to the PCB circuit board and the slider, respectively. The springs are evenly distributed in space between the PCB circuit board and the slider. The heating and contraction process of the shape memory alloy springs is controlled by the circuit to control the opening and closing of the current. The Waterbomb origami structure is surrounded by a shape memory alloy spring, slider, and slide rail assembly. The rear end of the Waterbomb origami is fixedly connected to the PCB circuit board. There are at least two traction ropes. One end of the traction rope is fixedly connected to the other side of the slider, and the other end is connected to the gripper finger at the front end of the Waterbomb origami. The process is as follows: two adjacent shape memory alloy short springs are heated by electricity and shrink, shortening the distance between the slider and the PCB circuit board, causing the slider to slide along the slide rail to the bottom; at the same time, under the traction of the slider, multiple traction ropes cause the front end of the origami gripper to bend inward, and the gripping module will exhibit a gripping state; when the two shape memory short springs stop being heated by electricity, the gripping module will gradually return to its initial open state.

2. The hybrid-driven flexible robotic arm based on origami structure according to claim 1, characterized in that, In the segment module, the pneumatic muscle consists of an airbag, a T-shaped seal, cable ties, and PU tubing. The airbag is wrapped in a woven bag and undergoes axial deformation after inflation. One end of the airbag is sealed by a T-shaped seal and fixed to the upper PCB circuit board by cable ties. The other end of the airbag is fixedly connected to the PU tubing, and multiple PU tubing are connected to a manifold. The other side of the manifold is connected to a main air supply pipe for supplying air to the airbag.

3. The hybrid-driven flexible robotic arm based on origami structure according to claim 2, characterized in that, In the segment module, the two PCBs have identical geometry; a circular hole is opened at the center, through which the air supply pipe passes. Multiple mounting slots are provided around the circular hole for fixing the pneumatic muscles. The T-shaped seal at the end of the pneumatic muscle is placed horizontally into the mounting slot and then rotated 90 degrees to be fixed to the PCB board. The air inlet of the pneumatic muscle is locked with a cable tie, which latches onto the circuit board and is then fixed by another horizontal cable tie. Multiple pneumatic muscles on each module are fixed to the PCB board in this way. The driving air pressure range of the pneumatic muscles is 0.125 MPa to 0.225 MPa.

4. The hybrid-driven flexible robotic arm based on origami structure according to claim 1, characterized in that, In the segment module, each PCB board is designed with shape memory alloy spring mounting holes, and each shape memory alloy spring is connected to the PCB board by bolts.

5. The hybrid-driven flexible robotic arm based on origami structure according to claim 1, characterized in that, In the segment module, both ends of the Yoshimura origami structure are connected to the PCB board by bolts; the Yoshimura origami structure is made of polyethylene terephthalate with a thickness of 0.125 mm, which is processed by a laser cutting machine.

6. The hybrid-driven flexible robotic arm based on origami structure according to claim 1, characterized in that, The segment module also includes a main control chip, a remote signal transmission chip, a circuit switch control chip, an inertial sensor, and related supporting circuits on its PCB board.

7. The hybrid-driven flexible robotic arm based on origami structure according to claim 1, characterized in that, In the segment module, each PCB board has four circular mounting holes near its outer edge for connecting segments to each other and to the grasping module.

8. The hybrid-driven flexible robotic arm based on origami structure according to claim 1, characterized in that, In the segment module, the dimensions of the two PCB boards meet the requirement that there is no interference before bending to the maximum angle.

9. The hybrid-driven flexible robotic arm based on origami structure according to claim 1, characterized in that, In the crawling module The slide rail is connected to the PCB board of the gripping module by bolts; The Waterbomb origami gripper structure is connected to the PCB by bolts. The Waterbomb origami gripper is made of polyethylene terephthalate film with a thickness of 0.125 mm, which is processed by a laser cutting machine. One end of the shape memory alloy short spring is fixed to the bottom of the slider by a bolt, and the other end is fixed to the PCB board by a bolt.

10. The hybrid-driven flexible robotic arm based on origami structure according to any one of claims 1-9, characterized in that, There are four body segment modules; in each body segment module, there are three pneumatic modules and four shape memory alloy springs in the pneumatic module; in the gripping module, there are four shape memory alloy springs; and there are four traction ropes.

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