Novel multi-joint shaft robot driven by non-coaxial variable stiffness elastic wires

Abstract

The application provides a novel multi-joint shaft manipulator with twisted wire non-coaxial variable stiffness elastic driving, relates to the fields of manipulator design, elastic driver and twisted wire driving system design, and comprises parallel twisted wire elastic driving joints, serial twisted wire elastic driving joints and an end execution module. The parallel twisted wire elastic driving joint adopts a sleeve and a twisted wire in parallel to act on the joint at a rotary joint to form a variable stiffness parallel elastic driver, the bending stiffness of the sleeve and the twisted wire is nonlinearly reduced with the increase of the bending angle, the energy can be absorbed and stored in the process of bending and straightening, and the energy can be released when needed; the serial twisted wire elastic driving joint realizes non-coaxial and long-distance translation driving by means of the sleeve and the twisted wire in series, combines the advantages of soft shaft driving (non-coaxial and long-distance) and twisted wire driving (lightweight and rotary translation movement), and the twisting and untwisting of the twisted wire can absorb and store energy in the working process, so that the energy efficiency of the whole system is improved.

Description

Technical Field

[0001] This invention relates to the fields of robot design, elastic actuators, and twisted wire drive system design. Specifically, it relates to a novel twisted wire non-coaxial variable stiffness elastic drive multi-joint robot suitable for complex application scenarios, which realizes non-coaxial output of the robot's end effector module and variable stiffness adjustment of the robot through a novel twisted wire elastic drive system. Background Technology

[0002] Wire-driven actuators, which replace the rope in traditional wire-driven actuators with metal wire, represent a new type of drive system. By using lightweight, low-noise, and low-cost wire instead of heavy, high-friction, and high-cost gearboxes, wire-driven actuators provide powerful tendon transmission and are widely used in the design and manufacture of soft actuators and artificial muscles. Wire-driven actuators bind one end of the wire to the point to be moved and the other end to the drive mechanism. As the drive motor rotates more, the winding of the wire gradually tightens, and the axial contraction of the wire reduces its axial length, converting the high-speed, low-torque rotary motion of the motor into low-speed, high-drive linear translational motion. They have a high transmission ratio and, utilizing their high energy efficiency and high power density, can achieve long-distance drive functions. However, in the current application of stranded wire actuators, simple linear translation functions can only be achieved through the twisting and unwinding of the motor, and the non-coaxial output function of the stranded wire actuator cannot be realized. In addition, traditional rigid manipulators often cannot adjust their own stiffness, have poor flexibility and environmental adaptability, and cannot meet the requirements of human-machine interaction, and cannot meet the usage requirements in complex working environments.

[0003] Currently, robotic arms are widely used in assembly, cutting, and material handling in manufacturing. However, existing robotic arms suffer from drawbacks such as complex structures and poor flexibility. Therefore, designing a simple, flexible, and safe robotic arm is a crucial issue that needs to be considered in current robotic arm design.

[0004] Furthermore, in some research on bionic robotic hands, traditional rigid robotic hands cannot achieve stiffness adjustment and cannot simulate the various excellent characteristics of biological arms. Their flexibility, softness, and adaptability need to be further improved to achieve more complex functions and better human-computer interaction capabilities. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a novel multi-joint axis manipulator with non-coaxial variable stiffness elastic drive. This manipulator enables the end effector module to achieve non-coaxial, long-distance drive and stiffness adjustment during operation, thereby improving the manipulator's working ability in complex environments. It features simple structure, low cost, convenient operation, and high working precision, and is suitable for many application scenarios such as medical robots, military special robots, and automated production and processing.

[0006] The objective of this invention is achieved through the following technical solution: A novel multi-joint axis manipulator with non-coaxial twisted wire variable stiffness elastic drive includes parallel twisted wire elastic drive joints, serial twisted wire elastic drive joints, and an end effector module. The parallel twisted wire elastic drive joint includes a front-end robotic arm, an end-end robotic arm, a sleeve, a sleeve connector, a bearing, a bearing holder, and a DC motor B. A bearing is installed at the end of the sleeve connector, and the sleeve is connected to the sleeve connector via the bearing, enclosing the twisted wire rotation area within the sleeve. This ensures that when the DC motor A is working, the rotation of the sleeve connector does not drive the sleeve to rotate, achieving independent control of the twisted wire. Simultaneously, it ensures that the twisted wire driver can operate along a predetermined trajectory during movement, achieving non-coaxial output. Furthermore, the sleeve prevents the twisted wire from directly contacting other components, preventing it from slackening onto other parts. The DC motor B drives the end-end robotic arm to rotate, and the twisted wire driver with the sleeve overcomes the limitation of traditional twisted wire drivers that can only perform linear translation, achieving non-coaxial output with the assistance of the sleeve.

[0007] The series-connected wire elastic drive joint includes a DC motor A, an end effector, an end effector slider, a sleeve, and a sleeve connector. The gripping module on the end effector module mates with the shaft hole of the end effector slider. The series-connected wire elastic drive joint realizes the positioning and resetting movements of the end effector module through the twisting and untwisting of the actuator wire, thereby achieving the positioning function of the end effector module.

[0008] The end effector module includes an actuator motor base, a small DC motor, an actuator front connector, an actuator twisted wire, an end slider, an actuator end connector, an actuator end connector, a front connecting rod, a central connecting rod, an end connecting rod, and a clamp. The small DC motor is installed at the center of the end slider. The actuator front connector is connected to the output shaft of the small DC motor. The actuator end connector is connected to the end slider through a hole. The actuator end connector has a cylindrical central shaft at its center. The actuator end connector is installed on the central shaft of the actuator end connector. One end of the twisted wire is connected to the actuator front connector, and the other end is connected to the actuator end connector.

[0009] The robotic arm is fixedly connected to the end effector of the robotic arm through the threaded hole at the bottom of the sleeve, and the end effector is delivered to the working position by adjusting the posture of the robotic arm.

[0010] This invention discloses a novel multi-joint axis manipulator with non-coaxial variable stiffness elastic drive, comprising parallel stranded wire elastic drive joints, series stranded wire elastic drive joints, and an end effector module. The parallel and series stranded wire elastic drive joints respectively perform bending and translational movements of the manipulator. Combining the advantages of flexible shaft drive and stranded wire drive, it achieves individual control of the working position and angle of the end effector module, avoiding the complex motion space problem associated with using servo motor joints to control the working position of the end effector module. Its structure is simple, low-cost, easy to operate, and highly accurate, making it suitable for applications such as automated manufacturing, medical robots, and special military robots. Specifically: The parallel twisted wire elastic drive joint uses a DC motor B at the first rotary joint, which, together with the sleeve and twisted wire, acts on the joint to form a variable stiffness parallel elastic actuator. The sleeve constrains the twisted wire to work along a predetermined trajectory. The operation of the DC motor B changes the angle of the end effector, thus altering the output direction of the twisted wire actuator, achieving non-coaxial output. Simultaneously, the sleeve ensures that the twisted wire does not directly contact other components. The bending stiffness of the sleeve and twisted wire decreases continuously with increasing bending angle, allowing for energy absorption and storage during bending and straightening, and release of this energy when needed, thereby improving the overall system energy efficiency.

[0011] The series-connected twisted wire elastic drive joint achieves non-coaxial, long-distance translational drive by means of DC motor A, sleeve, and twisted wire connected in series. Its end effector and end effector slider form a constraint that restricts the rotational movement of the end effector slider through a slide rail, so that the end effector slider only has linear displacement capability. The twisting and unwinding of the twisted wire gives the end effector slider tension and thrust respectively, thereby realizing the individual control of the linear motion of the end effector module, which combines the advantages of traditional soft shaft drive and twisted wire drive.

[0012] The end effector module is a gripping mechanism, which is fixedly connected to the end slider through the mounting hole to realize the gripping function of the target object. There are 12 links in total, divided into 4 groups. Each group contains 3 links. The 3 links in each group are named the front link, the center link, and the end link according to their distance from the clamp. One end of the front link is connected to the center link, and the other end of the front link is connected to the actuator end connector. The middle part of the center link is connected to the actuator end connector. One end of the end link is connected to the actuator end connector. The other end of the center link away from the front link and the other end of the end link are both connected to the clamp.

[0013] The stiffness adjustment function is achieved through the characteristics of the twisted wire and the flexible sleeve. As the number of rotations of the DC motor A increases, the winding of the twisted wire gradually tightens, and the axial contraction of the twisted wire leads to a shorter axial length. During the tightening process, the stiffness of the twisted wire changes continuously. During the bending process of the end effector, the flexible sleeve and the twisted wire have a certain bending stiffness to provide stable support and precise operation. At the same time, during the bending process of the end effector, the sleeve and the twisted wire can be equivalently formed as parallel elastic elements. Their bending stiffness decreases continuously with the increase of the bending angle. They can absorb and store energy during the bending process and release this energy when needed, thereby improving the energy efficiency of the entire system.

[0014] The end sleeve, middle sleeve, and front sleeve of the robotic arm mechanism are all connected by threads, which makes the assembly of the mechanism simple. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the working structure of a novel non-coaxial variable stiffness elastically driven multi-joint axis manipulator according to the present invention. Figure 2 This is a schematic diagram of the bending structure of a novel non-coaxial variable stiffness elastically driven multi-joint axis manipulator according to the present invention. Figure 3 and Figure 4 This is a schematic diagram of the disassembled structure of a novel non-coaxial variable stiffness elastically driven multi-joint axis manipulator according to the present invention. Figure 5 This is a schematic diagram showing the disassembled structure of the end effector module of a novel non-coaxial variable stiffness elastically driven multi-joint axis manipulator according to the present invention. Figure 6 This is a schematic diagram of the disassembled structure of the parallel twisted wire elastic drive joint of a novel twisted wire non-coaxial variable stiffness elastic drive multi-joint axis manipulator according to the present invention. Detailed Implementation

[0016] See Figures 1 to 6 A novel multi-joint axis manipulator with non-coaxial variable stiffness elastic drive for twisted wires is disclosed. The device includes parallel twisted wire elastic drive joints, series twisted wire elastic drive joints, and an end effector module. The entire device is based on a motor base 301 and a DC motor A302 at the bottom.

[0017] The parallel twisted wire elastic drive joint includes a front-end robotic arm 204, an end-end robotic arm 208, a sleeve 206, a sleeve connector 201, a bearing 203, a bearing mounting bracket 202, and a DC motor B205. The bearing 203 is installed at the end of the sleeve connector 201 and connected to the sleeve 206, so that when the DC motor A302 is working, the rotation of the sleeve connector 201 does not drive the rotation of the sleeve 206, thus achieving independent control of the twisted wire 207. The sleeve 206 encloses the twisting area of ​​the twisted wire 207. The front end of the sleeve 206 is coaxial with the sleeve connector 201, and the end of the sleeve 206 is coaxial with the end slider 101. The end-end robotic arm 208 is connected to the front-end robotic arm 204 through a hole, and the output shaft of the DC motor B205 passes through the coaxial hole of the end-end robotic arm 208 and the front-end robotic arm 204.

[0018] The series-connected twisted wire elastic drive joint includes an end slider 101 and the aforementioned DC motor A302, end robotic arm 208, sleeve 206, and sleeve connector 201. The DC motor A302, end slider 101, and sleeve 206 are concentrically arranged. The sleeve connector 201 is fixed to the output shaft of the DC motor A302. There are two end robotic arms 208, symmetrically distributed, with slide rails mounted on their inner sides. The outer side of the end slider 101 is slidably disposed on the inner side of the slide rail, thereby enabling the end slider 101 to have linear movement capability.

[0019] The end effector module includes an actuator motor base 102, a small DC motor 103, an actuator front connector 104, an actuator coil 105, an actuator end connector 106, an actuator end connector 107, a front connecting rod 108, a central connecting rod 109, an end connecting rod 110, and a clamp 111. The small DC motor 103 is mounted on the center of the end slider 101 via the actuator motor base 102. The actuator motor base 102 and the end slider 101 are connected by threads. The actuator front connector 104 is connected to the output shaft of the small DC motor 103. The actuator end connector 107 is connected to the end slider 101 via a hole. The actuator end connector 107 has a cylindrical central shaft at its center. The actuator end connector 106 is mounted on the central shaft of the actuator end connector 107. The actuator coil 105... 5. One end is connected to the actuator front connector 104, and the other end is connected to the actuator end connector 106. Preferably, there are four front connectors 108, four central connectors 109, and four end connectors 110, forming four groups. Each group includes one front connector 108, one central connector 109, and one end connector 110. One end of the front connector 108 is connected to one end of the central connector 109, and the other end of the front connector 108 is connected to the actuator end connector 106. The middle part of the central connector 109 is connected to the actuator end connector 107, and one end of the end connector 110 is connected to the actuator end connector 107. The end of the central connector 109 away from the front connector 108 and the end of the end connector 110 away from the actuator end connector 107 are both connected to the clamp 111.

[0020] The operation process of this novel non-coaxial variable stiffness elastically driven multi-joint robot is as follows: Before the device is in operation, the stranded wire 207 made of super-elastic nickel-titanium alloy wire is pre-twisted a certain number of times in the forward rotation direction of DC motor A302 to improve the response speed of the stranded wire drive. Preferably, there are two stranded wires 207 to generate sufficient unwinding and stretching thrust to push the end slider 101 outward. The top of the end slider 101 is provided with the mounting position of the end execution module.

[0021] Bending motion phase: The current work requires changing the angle of the end effector 208 to grasp the target object. The DC motor B205 drives the end effector 208 connected to it to rotate, causing the sleeve 206 and the wire 207 to produce similar bending angles along the bending direction of the end effector 208. At this time, the end slider 101 and the sleeve connector 201 are not coaxial.

[0022] End-effector clamping stage: The current work requires the clamp 111 to perform a clamping action to grasp the target object. The small DC motor 103 drives the actuator front connector 104 connected to it to rotate in the forward direction, causing the actuator coil 105 to twist and retract. Under the traction of the actuator coil 105, the actuator end connector 106 produces a positive linear displacement along the central axis of the actuator end connector 107. The front connecting rod 108, the central connecting rod 109, the end connecting rod 110, the actuator end connector 106, and the clamp 111 form a linkage slider mechanism. The displacement of the actuator end connector 106 drives the rotation of each connecting rod, thereby realizing the clamping action of the clamp 111 to grasp the target object.

[0023] Retracting the end effector module: The current task requires retracting the end effector module along the axis of the end effector arm 208. The DC motor A302 drives the sleeve connector 201 connected to it to rotate in the forward direction, causing the twisted wire 207 to twist and retract. The geometric constraint formed by the end slider 101 and the end effector arm 208 restricts the rotational movement of the end slider 101. Under the traction of the twisted wire 207, the end slider 101 produces a linear displacement along the axis. After the end effector module is retracted to the designated position, the DC motor A302 stops working.

[0024] End-effector release phase: The current work requires the clamp 111 to release the target object. The small DC motor 103 drives the actuator front connector 104 connected to it to rotate in the opposite direction, causing the actuator coil 105 to unwind. Under the elastic force of the unwinding and stretching of the actuator coil 105, the actuator end connector 106 generates a reverse linear displacement along the central axis of the actuator end connector 107. The displacement of the actuator end connector 106 drives the linkages to rotate, thereby realizing the release action of the clamp 111 and releasing the target object.

[0025] The end effector module ejection stage: The current work requires ejecting the end effector module along the axis of the end effector arm 208 without changing its working angle. The DC motor A302 rotates in the opposite direction, and the twisted wire 207 unwinds. During the unwinding process of the twisted wire 207, a reverse axial force is provided to eject the end effector module along the axis of the end effector arm 208. When the end effector module reaches the working position, the DC motor A302 stops working.

[0026] This novel multi-joint axis manipulator with non-coaxial variable stiffness elastic drive is based on a wire-driven design. It incorporates a wire-driven drive and traction device to adjust the end effector module, avoiding the bulky size and complex motion space issues of traditional manipulators that use servo joints to adjust the working position of the actuators, thus reducing the control difficulty of the device. During the bending process of the end effector arm 208, the sleeve 206 and the twisted wire 207 possess a certain bending stiffness to provide stable support and precise operation. Simultaneously, during the bending process of the end effector arm 208, the sleeve 206 and the twisted wire 207 can effectively form parallel elastic elements. Their bending stiffness decreases continuously with the increase of the bending angle, allowing them to absorb and store energy during bending and straightening, and release this energy when needed. This improves the energy efficiency of the entire system, is more in line with biological motion mechanisms, and enhances the manipulator's flexibility and energy utilization efficiency. It is suitable for applications such as automated manufacturing, medical robots, and special military robots.

[0027] This novel non-coaxial variable stiffness elastically driven multi-joint manipulator, based on a twisted wire drive design, employs a super-elastic nickel-titanium alloy wire twisted wire 207 and an actuator twisted wire 105. The twisting and contraction of the twisted wire 207 and actuator twisted wire 105 can respectively drive the axial contraction displacement of the end slider 101 and the actuator end connector 106. Furthermore, even without external system force acting on the end slider 101 and actuator end connector 106, the memory stretching ability of the twisted wire 207 and actuator twisted wire 105 during unwinding can induce reverse axial displacement, thereby achieving control over the linear working position of the end actuator module fixedly connected to the end slider 101.

[0028] By applying the above-mentioned parallel twisted wire elastic drive joints and series twisted wire elastic drive joints in the twisted wire drive system, the bending motion and translational motion of the manipulator pulled by the twisted wire 207 can be individually controlled, so that the twisted wire drive system has multi-configuration system characteristics.

[0029] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A novel multi-joint axis manipulator with non-coaxial twisted wire variable stiffness elastic drive, characterized in that, Includes parallel twisted wire elastic drive joints, series twisted wire elastic drive joints, and end effector modules; The parallel twisted wire elastic drive joint includes a front-end robotic arm, an end-end robotic arm, a sleeve, a sleeve connector, a bearing, a bearing mounting bracket, and a DC motor B. One end of the front-end robotic arm and one end of the end-end robotic arm are connected through a hole. The DC motor B is used to drive the front-end robotic arm and the end-end robotic arm to rotate relative to each other. The end-end robotic arm is directly connected to the output shaft of the DC motor B. The bearing is mounted on the end of the sleeve connector through the bearing mounting bracket and is connected to one end of the sleeve. The bearing is used to enable the sleeve and the sleeve connector to rotate relative to each other. The series-connected twisted wire elastic drive joint includes a DC motor A, an end slider, an end robotic arm, a sleeve, and a sleeve connector. The end slider, sleeve, sleeve connector, and DC motor A are concentrically arranged. The end slider is disposed in the slide rail of the end robotic arm. The end of the sleeve is connected to the end slider. The sleeve connector is installed at the front end of the sleeve. The DC motor A is fixedly connected to the end robotic arm. The sleeve connector is fixed to the output shaft of the DC motor A. It also includes stranded wire, which is disposed inside the sleeve. The two ends of the stranded wire are respectively connected to the sleeve connector and the end slider. The end slider can generate linear displacement along the axial direction under the traction of the stranded wire. The end effector module includes an actuator motor base, a small DC motor, an actuator front connector, actuator strands, an actuator end connector, an actuator end connector, a clamp, and the end slider. The small DC motor is mounted on the center of the end slider via the actuator motor base. The actuator front connector is connected to the output shaft of the small DC motor. The actuator end connector is connected to the end slider through a hole. The actuator end connector has a cylindrical central shaft at its center, and the actuator end connector is mounted on the central shaft of the actuator end connector. One end of the actuator strands is connected to the actuator front connector, and the other end of the actuator strands is connected to the actuator end connector. The end effector module further includes symmetrically arranged linkage assemblies, which include a front linkage, a central linkage, and an end linkage. One end of the front linkage is connected to one end of the central linkage, and the other end of the front linkage is connected to the actuator end connector. The middle part of the central linkage is connected to the actuator end connector, and one end of the end linkage is connected to the actuator end connector. The ends of the central linkage away from the front linkage and the ends of the end linkage away from the actuator end connector are both connected to the clamp.

2. The novel multi-joint axis manipulator with non-coaxial variable stiffness elastic drive according to claim 1, characterized in that, In the series-wound elastic drive joint, the existence of series elasticity is due to the helical torsion spring properties of the tightly wound twisted wires; in the series-wound elastic drive joint, the twisted wires have torsional stiffness during the translational motion of the end effector module; during the operation of the robot, the twisted wires are equivalent to forming a series of elastic elements, absorbing and releasing energy during twisting and untwisting, thereby improving the energy efficiency of the entire system.

3. The novel multi-joint axis manipulator with non-coaxial variable stiffness elastic drive according to claim 1, characterized in that, During the bending process of the end effector, the sleeve and the twisted wires of the parallel stranded wire elastic drive joint have a certain bending stiffness to provide stable support and precise operation. At the same time, during the bending process of the end effector, the sleeve and the twisted wires effectively form parallel elastic elements. The bending stiffness decreases continuously with the increase of the bending angle. Energy is absorbed and stored during the bending process and released when needed, thereby improving the energy efficiency of the entire system.

4. The novel multi-joint axis manipulator with non-coaxial variable stiffness elastic drive according to claim 1, characterized in that, In the parallel twisted wire elastic drive joint, the DC motor B cooperates with the end effector. The rotation of the DC motor B drives the end effector to rotate, causing the sleeve to bend. The sleeve is made of nylon material, which has good toughness and wear resistance. The sleeve ensures that the twisted wire moves along a predetermined trajectory, realizing the non-coaxial output of the twisted wire driver. At the same time, the twisted wire is protected from contact with other components by the sleeve, ensuring the smoothness and independence of the movement.

5. A novel multi-joint axis manipulator with non-coaxial variable stiffness elastic drive according to claim 1, characterized in that, The stranded wire is made of nickel-titanium alloy. By applying a set preload, it provides a reverse axial force to push the end effector module during the unwinding process, and enables it to achieve its own reset function without the aid of external components during the unwinding process.

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