A compact continuous robotic arm and its end-effector force measurement method

Abstract

This invention discloses a compact continuous robotic arm, comprising a continuous tube, a rope guide unit, a drive unit, and a motor unit. The rope guide unit includes a rope guide disc and a rope guide device. The drive unit includes a drive device, a drive rope, and a linear actuator. The continuous tube is fitted with a rope guide disc, which is connected to the rope guide device at the tube opening. The rope guide device is connected to the drive device after aligning with through holes. The linear actuators are disposed in the internal slots of the drive device and the motor unit, with each linear actuator facing a tension spring. Through unique design of the various module structures, modular installation methods, and rope guiding methods, this invention achieves a more compact overall mechanism, reducing the size of the continuous robotic arm hardware system and broadening the application scenarios of the continuous robotic arm.

Description

Technical Field

[0001] This invention relates to the field of continuous robotic arms, and more particularly to a compact continuous robotic arm and a method for measuring the end effector force thereon. Background Technology

[0002] A continuous robotic arm is a flexible and deformable robotic arm. Its main characteristic is that its main structure is not composed of rigidly linked components, but rather of flexible, continuous parts, enabling more natural and complex movements. Its applications are very broad, including endoscopic surgery in the medical field, detection and search and rescue in rescue missions, and flaw detection in manufacturing. Force sensing in a continuous robotic arm typically refers to the force between the end effector and the environment. By calculating the magnitude and direction of the force on the end effector based on changes in force sensor values, the operator can adjust the end effector's posture according to the force, avoiding excessive force that could damage the environment or the robotic arm. The compactness of a continuous robotic arm is mainly reflected in minimizing its size while maintaining the same functionality. In recent years, many researchers have developed various types of continuous robotic arms using different principles, such as ball-joint based continuous robotic arms, variable stiffness continuous robotic arms, and foldable continuous robotic arms. These technologies and products have greatly improved the flexibility and operability of continuous robotic arms, advancing their development.

[0003] However, existing continuous robotic arms still have many problems and challenges. For example, existing continuous robotic arms are not compact enough in terms of mechanism design, use complex drive and transmission devices, are bulky, are inconvenient to install, and are difficult to work in confined spaces or restricted environments. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that the mechanism of the continuous robot arm is not compact enough and it is difficult to work in a confined space or restricted environment.

[0005] To achieve the above objectives, the present invention provides a compact continuous robotic arm, which includes a continuous tube, a guide rope unit, a drive unit, and a motor unit.

[0006] The rope guiding unit includes a rope guiding disc and a rope guiding device; the driving unit includes a driving device, a driving rope, and a linear actuator.

[0007] The continuous tube is fitted with a guide rope disc, which is connected to the guide rope device at the tube opening. The guide rope device is connected to the drive device after aligning with the through hole. The linear actuator is located in the internal slot of the drive device and the motor unit. Each linear actuator is opposite to a tension spring.

[0008] Through the unique design of the structure of each module, the modular installation method, and the rope-walking method, the present invention makes the overall mechanism more compact, reduces the size of the continuous robot arm hardware system, and broadens the application scenarios of the continuous robot arm.

[0009] In a preferred embodiment of the present invention, an interference fit is used between the continuum tube and the guide rope reel;

[0010] The continuum tube has at least seven guide rope discs, each with a fan-shaped notch. The guide rope discs are connected to the drive rope via a rope sleeve.

[0011] In another preferred embodiment of the invention, the surface of the continuum tube includes rhomboid grooves symmetrical along the axis;

[0012] The two adjacent slots along the axial direction have an included angle of 85 to 95°, and the slots between the starting section and the middle section and between the middle section and the end section have an included angle of 40 to 50° along the axial direction.

[0013] In another preferred embodiment of the present invention, the rope guide device is provided with rope guide grooves symmetrically along the axis;

[0014] The rope guide groove includes a straight guide groove, an open rope guide groove, a closed rope guide groove, and a rope guide hole.

[0015] In another preferred embodiment of the present invention, the front end of the drive device includes a semi-circular guide rope groove for placing the drive rope connecting the linear actuator and the tension spring; the semi-circular guide rope groove acts as a fixed pulley structure, and through the drive rope connecting the linear actuator and the tension spring, the displacement ratio of the linear actuator and the tension spring is 1:1.

[0016] The main body of the drive device is provided with a semi-circular groove along the axis to provide movement space for the linear actuator and the tension spring.

[0017] In another preferred embodiment of the present invention, the motor unit includes a motor body slot and a motor rear cover. The surface of the motor body slot is provided with set screw holes, and the motor rear cover is provided with wiring holes for connecting the linear driver to a power supply.

[0018] The motor unit is internally provided with a body groove and a tension spring support, and the tension spring is connected to the tension spring support.

[0019] In this invention, axial movement is controlled by the rear cover of the motor pressing against the linear actuator, while circumferential and radial movement are restricted by the shape of the slot in the motor. The set screws on the surface of the slot in the motor body provide auxiliary fixing. Because the slot in the motor has some allowance, the set screws can restrict circumferential and radial movement to a certain extent, and axial movement is restricted by frictional force.

[0020] In another preferred embodiment of the invention, the semi-circular groove is aligned with and connected to the drive unit and the motor body groove via bolts and nuts through a connecting through hole via a tension spring support and a linear actuator drive rod.

[0021] In another preferred embodiment of the present invention, the connection method of the drive rope includes: one end is connected to a tension spring, and the other end passes through a waist-shaped hole and a semi-circular guide rope groove, and then returns to the opposite waist-shaped hole to be connected to the opposite linear actuator.

[0022] or,

[0023] The connection method of the drive rope includes: one end is connected to a tension spring or a linear actuator, and the other end is connected to the guide rope disc through a rope sleeve after passing through a waist-shaped hole, a linear guide rope groove, an open guide rope groove, a closed guide rope groove, a guide rope hole, and a slit groove.

[0024] On the other hand, the present invention provides a method for measuring the end effector force of a compact continuous manipulator as described in the first aspect, the method comprising:

[0025] (1) When the linear actuator is in the retracted state, f c =f e -f k ;

[0026] (2) When the linear actuator is in the stretched state, f c =f k -f e ;

[0027] Among them, f e f is the force acting on the linear actuator. k For the elastic force of the stretched spring, f c The force exerted by the drive rope on the end guide rope reel connecting the linear actuator and the guide rope reel.

[0028] In a preferred embodiment of the present invention, f e This is obtained through force sensing integrated into the linear actuator;

[0029] f k It is calculated using the spring constant, initial tension length, and displacement of the tension spring;

[0030] The bending condition of the continuum tube and the dynamic model of the continuum robot arm are used to calculate the theoretical force on the force sensor under no external force. Then, based on f... c The external forces acting on the continuous manipulator can be deduced from the theoretical forces, the bending condition of the continuous tube, and the dynamic model of the continuous manipulator.

[0031] Most current continuous robotic arms focus on acquiring environmental information through vision, lacking force perception and feedback, making it difficult to interact with the environment. This can easily lead to excessive forces between the robotic arm and the environment during the task, causing damage to the environment or the robotic arm.

[0032] This invention provides an end-effector force measurement method for a continuous manipulator based on a linear actuator with force sensing function. By integrating force sensing function into the continuous manipulator through force analysis and continuous manipulator dynamics, the method enhances the interaction capability between the continuous manipulator and the environment, and improves the operator's awareness of the environment.

[0033] Technical effect

[0034] (1) Through the ingenious structural design of each module, the continuous robot arm is made more compact, reducing the volume of the continuous robot arm hardware system and expanding the application scenarios of the continuous robot arm.

[0035] (2) The modular design with a unified connection port makes the present invention easy to assemble and disassemble and highly expandable.

[0036] (3) The end-effector force measurement method based on linear actuator with force sensing function enhances the interaction capability between the continuous manipulator and the environment, and improves the operator's awareness of the environment.

[0037] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a compact continuous robotic arm according to a preferred embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the rope-walking method of a compact continuous robotic arm according to a preferred embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the structure of the continuum tube and the guide rope disc according to a preferred embodiment of the present invention;

[0041] Figure 4 This is a cross-sectional view of a rope guide device according to a preferred embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the structure of a driving device according to a preferred embodiment of the present invention;

[0043] Figure 6 This is a schematic diagram of the assembly of the machine body slot, motor rear cover and linear driver according to a preferred embodiment of the present invention;

[0044] Figure 7 This is an exploded view of the motor housing slot, motor rear cover, and linear driver assembly according to a preferred embodiment of the present invention;

[0045] Figure 8 This is a schematic diagram showing the position of the drive rope of one set of actuators of a compact continuous robotic arm according to a preferred embodiment of the present invention, and the force exerted by the linear actuator when it is in the retracted state.

[0046] Figure 9 This is a schematic diagram showing the position of the drive rope of one set of actuators of a compact continuous robotic arm according to a preferred embodiment of the present invention, and the force exerted when the linear actuator is in a stretched state.

[0047] Wherein: 1-Continuous tube, 11-Slotted, 2-Rope guide disc, 21-Slit groove, 3-Rope guide device, 31-Connecting through hole, 32-Set screw hole, 33-Closed rope guide groove, 34-Rope guide hole, 35-Instrument through hole, 36-Inner baffle, 37-Open rope guide groove, 38-Straight rope guide groove, 39-Concentric cylindrical slot, 4-Drive device, 41-Connecting through hole, 42-Semi-circular rope guide groove, 43-Oval hole, 44-Semi-circular groove, 5-Motor body groove, 51-Connecting through hole, 52-Set screw hole, 53-Tension spring support, 54-Body groove, 6-Motor rear cover, 61-Connecting through hole, 62-Way hole, 7-Linear driver, 8-Drive rope, 9-Tension spring. Detailed Implementation

[0048] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0049] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0050] like Figures 1 to 7As shown, this invention provides a compact continuous robotic arm, comprising a continuous tube 1, a guide reel 2, a guide device 3, a drive device 4, a drive rope 8, a tension spring 9, a motor body slot 5, a motor rear cover 6, and linear actuators 7. The continuous tube 1 is fitted with the guide reel 2, and the continuous tube 1 and the guide reel 2 are interference-fitted. The guide reel 2 at the tube opening of the continuous tube 1 is connected to the concentric cylindrical slot 39 of the guide device 3, and the notched slot 21 is aligned with the guide hole 34 and fixed with a set screw through the set screw hole 32. The guide device 3 and the drive device 4 are aligned with the connecting through hole 31 and the connecting through hole 41 and connected with bolts and nuts. After placing the four linear actuators 7 into the body slot 54, aligning the connecting through holes 51 and 61, the motor body slot 5 and the motor rear cover 6 are connected with bolts and nuts. After aligning the semi-circular groove 44 and connecting it to the tension spring support 53 and the drive rod of the linear actuator 7, the drive device 4 and the motor body groove 5 are connected by bolts and nuts through the connecting through holes 41 and 51. The tension spring 9 is connected to the tension spring support 53. According to the design of the motor body groove 5, each linear actuator 7 has one tension spring 9 in opposite direction. The drive rope 8 has two different connection methods. One method is to connect one end to the tension spring 9 and the other end through the waist-shaped hole 43, the semi-circular guide rope groove 42, and then back to the opposite waist-shaped hole 43 to connect with the opposite linear actuator 7, thereby achieving a 1:1 displacement ratio between the linear actuator 7 and the tension spring 9. The other method is to connect one end to the tension spring 9 / linear actuator 7 and the other end through the waist-shaped hole 43, the linear guide rope groove 38, the open guide rope groove 37, the closed guide rope groove 33, the guide rope hole 34, and multiple notched grooves 21 to the end / middle guide rope disc 2 through a rope sleeve, thereby realizing the control of the continuous tube by the linear actuator 7 / tension spring 9.

[0051] like Figure 3 As shown, the continuous tube 1 is fitted with seven guide rope discs 2. The continuous tube 1 uses two rhomboid slots 11 that are symmetrical along the axis, and adjacent slots 11 have a 90° angle along the axis. The slots 11 between the starting section and the middle section and between the middle section and the end section have a 45° angle along the axis. Each guide rope disc 2 has eight fan-shaped notches. Four drive ropes 8, which are rotationally symmetrical about 90° along the axis, pass through the four guide rope discs 2 from the starting section to the middle section and are connected to the middle guide rope disc 2 through rope loops. The remaining four drive ropes 8 pass through all seven guide rope discs 2 and are connected to the end guide rope disc 2 through rope loops.

[0052] like Figure 4 As shown, the rope guide device 3 has eight rope guide grooves symmetrically arranged along its axis. Each rope guide groove consists of a straight guide groove 38, an open rope guide groove 37, a closed rope guide groove 33, and a rope guide hole 34. An instrument through-hole 35 is used to pass additional instruments. An inner baffle 36 is used to form a closed space.

[0053] like Figure 5 As shown, the front end of the drive device 4 is designed with four semi-circular guide rope grooves 42, which are used to make the displacement ratio of the linear actuator 7 and the tension spring 9 1:1 through the drive rope 8 connecting the linear actuator 7 and the tension spring 9. The main body has eight semi-circular grooves 44 along the axis to serve as the movement space for the linear actuator 7 and the tension spring 9.

[0054] like Figure 6 and 7 As shown, four housing slots 54 and four tension spring supports 53 are arranged in a schematic manner. Due to the redundancy of the internal space of the housing slots 54, the movement of the linear actuator 7 is further restricted by set screws through the set screw holes 52. Wiring holes 62 are provided to allow the linear actuator 7 to be connected to a power source.

[0055] In one specific embodiment of the invention, the outer diameter is 70 mm, enabling control of a total of four degrees of freedom across two continuous tube segments, each capable of bending at least ±90°. Through modular assembly and disassembly, the invention can also achieve specific functions as needed, such as changing the control degrees of freedom.

[0056] like Figure 8 and Figure 9 As shown, this invention also provides a method for measuring the force at the end effector of a continuous robotic arm based on a linear actuator with force sensing function. When the linear actuator 7 is in the retracted state, the forces acting on each part are as follows: Figure 7 At this time, the drive rope 8 connecting the tension spring 9 and the guide rope disc 2 has no tension. e f is the force acting on the linear actuator 7. k For the elastic force of spring 9, f c For the force exerted by the drive rope 8 on the end guide rope disk 2 of the linear actuator 7 and the guide rope disk 2, f a1 with f a4 For the tension of the drive rope 8 connecting the linear actuator 7 and the guide rope disc 2, f a2 with f a3 The tension of the drive rope 8 connecting the linear actuator 7 and the tension spring 9. Satisfying f e =f a2 +f a4 f a2 =f a3 =f k f a1 =f a4 =f c Therefore, f c =f e -f k When the linear actuator 7 is in the tension state, the forces acting on each part are as follows: Figure 8 At this time, the drive rope 8 connecting the linear actuator 7 and the guide rope disc 2 has no tension. ef is the force acting on the linear actuator 7. k For the elastic force of spring 9, f c For the force exerted by the drive rope 8 on the end guide rope disc 2, connecting the tension spring 9 and the guide rope disc 2, f a1 with f a4 To control the tension of the drive rope 8 connecting the tension spring 9 and the guide rope disc 2, f a2 with f a3 The tension of the drive rope 4 connecting the linear actuator 7 and the tension spring 9. Satisfying f k =f a2 +f a4 f a2 =f a3 =f e f a1 =f a4 =f c Therefore, f c =f k -f e Among them, f e The force can be obtained through the force sensor integrated in the linear actuator 7; since the displacement ratio of the linear actuator 7 and the tension spring 9 is 1:1, the displacement of the tension spring 9 can be calculated from the displacement of the linear actuator 7; f k The force can be calculated using the spring constant of tension spring 9, the initial tension length, and the displacement. Based on the bending condition of the continuum tube 1 and the dynamic model of the continuum robotic arm, the theoretical forces acting on each force sensor under no external force are calculated. Then, based on f... c The external forces acting on the continuous manipulator can be deduced from the theoretical force, the bending condition of the continuous tube 1, and the dynamic model of the continuous manipulator.

[0057] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A compact continuous robotic arm, characterized in that, The compact continuous robotic arm includes a continuous tube, a guide rope unit, a drive unit, and a motor unit; The rope guiding unit includes a rope guiding disc and a rope guiding device; the driving unit includes a driving device, a driving rope, and a linear actuator. The continuous tube is fitted with a guide rope disc, which is connected to the guide rope device at the tube opening. The guide rope device is connected to the drive device after aligning with the through hole. The linear actuator is located in the internal slot of the drive device and the motor unit. Each linear actuator is opposite to a tension spring. The surface of the continuum tube includes rhomboid grooves that are symmetrical along the axis. The two adjacent slots along the axial direction have a 90° included angle, and the slots between the starting section and the middle section and between the middle section and the end section have a 45° included angle along the axial direction. The front end of the drive device includes a semi-circular guide groove for placing the drive rope connecting the linear actuator and the tension spring; the main body of the drive device is provided with a semi-circular groove along the axis to provide movement space for the linear actuator and the tension spring. The motor unit includes a motor body slot and a motor rear cover. The surface of the motor body slot is provided with set screw holes, and the motor rear cover is provided with wiring holes for connecting the linear driver to the power supply. The motor unit includes a body slot and a tension spring support, wherein the tension spring is connected to the tension spring support; The semi-circular groove is aligned and connected to the drive rod of the tension spring support and linear actuator, and the drive unit and motor body groove are connected by bolts and nuts through the connecting through hole.

2. The compact continuous robotic arm according to claim 1, characterized in that, The continuous tube and the guide rope reel are fitted with an interference fit. The continuum tube has at least seven guide rope discs, each with a fan-shaped notch. The guide rope discs are connected to the drive rope via a rope sleeve.

3. The compact continuous robotic arm according to claim 1, characterized in that, The rope guide device is symmetrically provided with rope guide grooves along the axis. The rope guide groove includes a straight guide groove, an open rope guide groove, a closed rope guide groove, and a rope guide hole.

4. The compact continuous robotic arm according to claim 1, characterized in that, The connection method of the drive rope includes: one end is connected to a tension spring, and the other end passes through a waist-shaped hole and a semi-circular guide rope groove, and then returns to the opposite waist-shaped hole to connect with the opposite linear actuator. or, The connection method of the drive rope includes: one end is connected to a tension spring or a linear actuator, and the other end is connected to the guide rope disc through a rope sleeve after passing through a waist-shaped hole, a linear guide rope groove, an open guide rope groove, a closed guide rope groove, a guide rope hole, and a slit groove.

5. A method for measuring the end-effector force of a compact continuous robotic arm according to any one of claims 1-3, characterized in that, The method includes: (1) When the linear actuator is in the retracted state, f c = f e -f k ; (2) When the linear actuator is in the tension state, f c = f k -f e ; Among them, f e f is the force acting on the linear actuator. k For the elastic force of the stretched spring, f c The force exerted by the drive rope on the end guide rope reel connecting the linear actuator and the guide rope reel.

6. The method for measuring the end-effector force of the compact continuous robotic arm according to claim 5, characterized in that, f e This is obtained through force sensing integrated into the linear actuator; f k It is calculated using the spring constant, initial tension length, and displacement of the tension spring; The bending condition of the continuum tube and the dynamic model of the continuum robot arm are used to calculate the theoretical force on the force sensor under no external force. Then, based on f... c The external forces acting on the continuous manipulator can be deduced from the theoretical forces, the bending condition of the continuous tube, and the dynamic model of the continuous manipulator.

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