Miniature hexapod crawling robot based on shape memory alloy driving

Abstract

The invention discloses a miniature hexapod crawling robot based on shape memory alloy driving. The miniature hexapod crawling robot comprises a robot body, leg structures, internal guide wheels, internal shape memory alloy wires, external guide wheels and external shape memory alloy wires. The six leg structures are symmetrically distributed on the left side and the right side of the fuselage, and shin joint shafts of the leg structures are rotationally connected with the fuselage; three internal guide wheels are rotationally mounted on the left and right sides of the inner wall of the machine body bottom plate respectively; three external guide wheels are rotationally mounted on the left and right sides of the outer wall of the machine body bottom plate respectively; each leg structure corresponds to one internal shape memory alloy wire and one external shape memory alloy wire, one end of each internal shape memory alloy wire is fixedly connected with one side, provided with the corresponding leg structure, of the fuselage, and the other end of each internal shape memory alloy wire is wound on a shin joint shaft of the corresponding leg structure after bypassing a corresponding internal guide wheel on the opposite side of the corresponding leg structure; one end of the external shape memory alloy wire is fixedly connected with one side of the body provided with the leg structure, and the other end bypasses the corresponding external guide wheel on the opposite side of the leg structure and then penetrates through the body bottom plate to be fixedly connected with the middle of the leg section of the leg structure. And by increasing the deformation quantity of the shape memory alloy wire, the leg walking and putting amplitude is increased, and the walking speed is higher.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-robots, and specifically relates to a micro hexapod crawling robot driven by shape memory alloy. Background Art

[0002] With the development of robot technology, micro bionic robots have received extensive attention. The size of micro bionic robots is usually between a few centimeters and dozens of centimeters, and they are particularly suitable for tasks such as earthquake disaster rescue, narrow pipeline exploration, and data collection. Compared with wheeled structures, legged robots show better adaptability in complex terrains.

[0003] The actuator is a key factor affecting the performance of micro bionic robots. Although motors are widely used due to their high controllability and precision, they have deficiencies such as low degrees of freedom, poor flexibility, large weight, and high noise, which are not conducive to the miniaturization of robots. Therefore, researchers have explored actuators made of materials such as shape memory alloy (SMA), ionic polymer metal composite (IPMC), piezoelectric ceramics, and dielectric elastomers. SMA actuators have advantages such as high power-to-weight ratio, compact size, and quiet operation, and are an ideal choice for the design of micro-robots. However, existing SMA-driven robots all have problems such as slow traveling speed, which limits their practical applications.

[0004] Therefore, the present invention designs a micro hexapod crawling robot driven by shape memory alloy, and by increasing the stroke of the shape memory alloy wire, the amplitude of the robot's leg movement and leg lifting is increased to improve the traveling speed of the robot. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a micro hexapod crawling robot driven by shape memory alloy.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A micro hexapod crawling robot driven by shape memory alloy, characterized in that the robot comprises a fuselage, a leg structure, an internal guide wheel, an internal shape memory alloy wire, an external guide wheel, and an external shape memory alloy wire;

[0008] Six leg structures are symmetrically distributed on the left and right sides of the fuselage. The tibia shaft of the leg structure is rotatably connected to the fuselage. Three internal guide wheels are respectively rotatably installed on the left and right sides of the inner wall of the fuselage bottom plate, and three external guide wheels are respectively rotatably installed on the left and right sides of the outer wall of the fuselage bottom plate. The leg movement of each leg structure is driven by an internal shape memory alloy wire. One end of the internal shape memory alloy wire is fixedly connected to the side of the fuselage where the leg structure is installed. After the internal shape memory alloy wire bypasses the corresponding internal guide wheel on the opposite side of the leg structure, the other end is wound around the tibia shaft of the leg structure. The landing movement of each leg structure is driven by an external shape memory alloy wire. One end of the external shape memory alloy wire is fixedly connected to the side of the fuselage where the leg structure is installed. After the external shape memory alloy wire bypasses the corresponding external guide wheel on the opposite side of the leg structure, the other end penetrates the fuselage bottom plate and is fixedly connected to the middle of the femur of the leg structure.

[0009] Further, the leg structure includes a tibia, a femur, a femur return spring, a tibia shaft, and a tibia return spring. The tibia shaft is vertically installed in the fuselage and is respectively rotatably connected to the cover and the bottom plate of the fuselage at the upper and lower ends. The tibia is fixed on the tibia shaft. One end of the tibia return spring is fixedly connected to the side wall of the fuselage, and the other end is fixedly connected to the inner wall of the tibia. The axis of the tibia return spring is perpendicular to the tibia shaft in space. One end of the femur penetrates the tibia and is rotatably connected to the middle of the tibia. One end of the femur return spring is fixedly connected to the end of the femur that penetrates the tibia, and the other end is fixedly connected to the end ear of the tibia. The axis of the femur return spring is parallel to the tibia shaft.

[0010] Further, the femur includes a femur body. One end of the femur body is provided with an extension portion that extends into the tibia, and the middle of the extension portion is rotatably connected to the middle of the tibia.

[0011] Further, the internal shape memory alloy wire and the external shape memory alloy wire are made of nickel-titanium alloy.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] 1. The present invention drives the robot to walk through twelve shape memory alloy wires. Each leg structure is independently controlled by an internal shape memory alloy wire and an external shape memory alloy wire. Therefore, the robot has powerful movement capabilities. After the shape memory alloy wire bypasses the corresponding guide wheel on the opposite side of the leg structure and then is connected to the leg structure, the length of the shape memory alloy wire is increased. Therefore, the deformation amount of the shape memory alloy wire is larger, the amplitude of leg movement and downward leg lowering is increased, and it has a good driving effect, enabling the robot to have a faster traveling speed. Experimental results show that the traveling speed of the existing shape memory alloy-driven micro hexapod crawling robot is 0.03 body lengths / s, while the traveling speed of the robot of the present invention is greater than or equal to 0.07 body lengths / s, verifying that the robot of the present invention has a faster traveling speed.

[0014] 2. The tibia of the leg structure rotates and resets through the internal shape memory alloy wire and the tibia reset spring, and the femur rotates and resets through the external shape memory alloy wire and the femur reset spring. The shape memory alloy wire and the corresponding reset spring oppose each other, realizing rapid leg extension and leg swinging actions, giving full play to the advantages of the shape memory alloy wire such as light weight, no noise, large output force, and simple control, and realizing the adaptability of the robot to complex environments and tasks on the basis of a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0016] Figure 2 is a schematic diagram of the structure of the present invention with the machine cover removed;

[0017] Figure 3 is Figure 2 a top view of

[0018] Figure 4 is Figure 2 a bottom view of

[0019] Figure 5 is a schematic diagram of the leg structure of the present invention;

[0020] Figure 6 is an exploded view of the leg structure of the present invention;

[0021] Figure 7 is a schematic diagram of the structure of the fuselage of the present invention;

[0022] In the figure: 1 - fuselage; 2 - machine cover; 3 - leg structure; 4 - internal guide wheel; 5 - internal shape memory alloy wire; 6 - external guide wheel; 7 - external shape memory alloy wire;

[0023] 101 - internal guide wheel connecting seat; 102 - spring connection hole; 103 - micro through hole; 104 - tibia shaft connection hole; 301 - tibia; 302 - femur; 303 - femur reset spring; 304 - tibia shaft; 305 - external shape memory alloy wire connecting seat; 306 - tibia reset spring. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The technical solutions of the present invention will be described in detail below in conjunction with the drawings and specific embodiments, but the protection scope of this application is not limited thereby.

[0025] The present invention provides a micro hexapod crawling robot driven by shape memory alloy (hereinafter referred to as the robot, see Figures 1-7 ), which includes a fuselage 1, a leg structure 3, an internal guide wheel 4, an internal shape memory alloy wire 5, an external guide wheel 6, and an external shape memory alloy wire 7;

[0026] Six leg structures 3 are symmetrically distributed on the left and right sides of the fuselage 1. The tibia shaft 304 of the leg structure 3 is rotatably connected to the fuselage 1. Three internal guide wheels 4 are respectively rotatably installed on the left and right sides of the inner wall of the bottom plate of the fuselage 1, and three external guide wheels 6 are respectively rotatably installed on the left and right sides of the outer wall of the bottom plate of the fuselage 1. The leg swinging motion of each leg structure 3 is driven by an internal shape memory alloy wire 5. One end of the internal shape memory alloy wire 5 is fixedly connected to the side of the fuselage 1 where the leg structure 3 is installed. After the internal shape memory alloy wire 5 bypasses the corresponding internal guide wheel 4 on the opposite side of the leg structure 3, the other end is wound around the tibia shaft 304 of the leg structure 3. The internal shape memory alloy wire 5 contracts when electrified, driving the tibia shaft 304 to rotate around the fuselage 1 towards the tail of the robot, so that the tibia 301 of the leg structure 3 rotates in the horizontal plane towards the forward direction of the robot, realizing the forward leg swing. Similarly, the landing motion of each leg structure 3 is driven by an external shape memory alloy wire 7. One end of the external shape memory alloy wire 7 is fixedly connected to the side of the fuselage 1 where the leg structure 3 is installed. After the external shape memory alloy wire 7 bypasses the corresponding external guide wheel 6 on the opposite side of the leg structure 3, the other end penetrates through the bottom plate of the fuselage 1 and is fixedly connected to the middle of the femur 302 of the leg structure 3. The external shape memory alloy wire 7 is in its original length when powered off, and the femur 302 does not rotate relative to the tibia 301. On the contrary, the external shape memory alloy wire 7 contracts when electrified, driving the femur 302 to rotate downward around the tibia 301, realizing the landing. Therefore, each leg structure 3 corresponds to an internal shape memory alloy wire 5 and an external shape memory alloy wire 7, and forms an integral body with the internal guide wheel 4 and the external guide wheel 6 on the opposite side.

[0027] The leg structure 3 includes a tibia 301, a femur 302, a femur return spring 303, a tibia shaft 304, and a tibia return spring 306; the tibia shaft 304 is vertically installed in the fuselage 1 and is rotatably connected to the cover 2 and the bottom plate of the fuselage 1 at the upper and lower ends respectively. The tibia 301 is fixed on the tibia shaft 304. One end of the tibia return spring 306 is fixedly connected to the side wall of the fuselage 1, and the other end passes through the tibia 301 and is fixedly connected to the inner wall of the tibia 301. The axis of the tibia return spring 306 is perpendicular to the tibia shaft 304 in the spatial position. During the process of stepping forward, the tibia return spring 306 is compressed to store elastic potential energy. After the leg movement is completed, the tibia return spring 306 releases the elastic potential energy to restore to its original state, realizing the reset of the tibia 301, and at the same time stretching the internal shape memory alloy wire 5 to restore to its initial state. The tibia return spring 306 and the internal shape memory alloy wire 5 form a confrontation; one end of the femur 302 passes through the tibia 301 and the femur 302 is rotatably connected to the middle part of the tibia 301. The other end of the femur 302 is a free end, equivalent to the foot; one end of the femur return spring 303 is fixedly connected to the end of the femur 302 passing through the tibia 301, and the other end is fixedly connected to the end ear on the inner side of the tibia 301. The axis of the femur return spring 303 is parallel to the tibia shaft 304. During the landing process, the femur return spring 303 is compressed. After the landing is completed, the femur return spring 303 restores to its initial state, and the femur 302 is reset, realizing the leg lift, and at the same time stretching the external shape memory alloy wire 7 to restore to its initial state. The femur return spring 303 and the external shape memory alloy wire 7 form a confrontation.

[0028] The femur 302 includes a femur body and an extension part located at one end of the femur body. The extension part extends into the tibia 301. The middle part of the extension part is rotatably connected to the middle part of the tibia 301. The end of the extension part is connected to the femur return spring 303; an external shape memory alloy wire connecting seat 305 is provided at the intersection of the femur body and the extension part.

[0029] Three notches are symmetrically opened on the left and right side walls of the fuselage 1 for installing the leg structure 3. The size of the notches needs to ensure that the leg structure 3 can reciprocally rotate within a certain angle range to realize the leg movement and the leg retraction actions. The bottom plate of the fuselage 1 is respectively provided with a micro through hole 103 and a tibia shaft connection hole 104 at the notch positions. The micro through hole 103 is for the external shape memory alloy wire 7 to pass through, and the tibia shaft connection hole 104 is for installing the tibia shaft 304. The side wall of the fuselage 1 is provided with a spring connection hole 102 at the notch for connecting the tibia return spring 306. An internal guide wheel connection seat 101 is provided at a position adjacent to the notch on the bottom plate of the fuselage 1 for installing the internal guide wheel 4.

[0030] Both the internal guide wheel 4 and the external guide wheel 6 are made of non-conductive ceramic wheels. The internal shape memory alloy wire 5 and the external shape memory alloy wire 7 are made of nickel-titanium alloy.

[0031] The working principle and process of the present invention are as follows:

[0032] Taking a single leg structure 3 as an example, the external shape memory alloy wire 7 is powered off and in its original length; when the external shape memory alloy wire 7 is powered on, it contracts, driving the leg segment 302 to rotate downward around the tibia segment 301 to achieve landing; then, when the internal shape memory alloy wire 5 is powered on, it contracts, driving the tibia shaft 304 to rotate around the fuselage 1 in the forward direction of the robot, causing the entire leg structure 3 to rotate in the forward direction of the robot to achieve forward leg movement; after the landing and leg movement actions are completed, the internal shape memory alloy wire 5 and the external shape memory alloy wire 7 stop being powered on, and the internal shape memory alloy wire 5 returns to its initial state under the action of the tibia return spring 306, and the external shape memory alloy wire 7 returns to its initial state under the action of the leg segment return spring 303. By cycling in this way, the internal shape memory alloy wire 5 and the external shape memory alloy wire 7 are cyclically powered on and off to achieve the walking of the robot.

[0033] For the entire robot, by controlling the movement of the twelve leg structures 3 and controlling the voltage on and off of different shape memory alloy wires according to a certain rule, various customizable gait movements such as triangular gait, ripple gait, and turning gait can be achieved. Specifically, the triangular gait is the gait of a hexapod crawling robot moving forward quickly on a flat ground, with two legs on one side and one leg on the opposite side touching the ground at the same time, forming an isosceles triangle. The ripple gait is a slow gait for a hexapod crawling robot to move forward stably on a rough surface, with four legs touching the ground at the same time to ensure stability, and the other two legs take steps. The turning gait is as the name implies. In this gait, three legs on one side can move synchronously, while the three legs on the opposite side are stationary, achieving the turning of the robot. In addition, by installing devices such as cameras and sensors on the robot, tasks such as monitoring, reconnaissance, and exploration can be performed.

[0034] Matters not described in the present invention are applicable to the prior art.

Claims

1. A micro hexapod crawling robot driven by shape memory alloy, characterized in that: The robot comprises a body, a leg structure, an internal guide wheel, an internal shape memory alloy wire, an external guide wheel and an external shape memory alloy wire; The six leg structures are symmetrically distributed on the left and right sides of the fuselage, and the tibia shaft of the leg structure is rotatably connected to the fuselage; three internal guide wheels are rotatably installed on the left and right sides of the inner wall of the fuselage bottom plate, and three external guide wheels are rotatably installed on the left and right sides of the outer wall of the fuselage bottom plate; the stepping action of each leg structure is driven by an internal shape memory alloy wire, one end of the internal shape memory alloy wire is fixedly connected to one side of the leg structure installed on the fuselage, and after the internal shape memory alloy wire passes around the corresponding internal guide wheel on the opposite side of the leg structure, the other end is wrapped around the tibia shaft of the leg structure; the landing action of each leg structure is driven by an external shape memory alloy wire, one end of the external shape memory alloy wire is fixedly connected to one side of the leg structure installed on the fuselage, and after the external shape memory alloy wire passes around the corresponding external guide wheel on the opposite side of the leg structure, the other end passes through the fuselage bottom plate and is fixedly connected to the middle part of the leg section of the leg structure.

2. The shape memory alloy-driven micro hexapod crawling robot according to claim 1, characterized in that: The leg structure includes a tibia, a leg segment, a leg segment reset spring, a tibia shaft and a tibia reset spring; the tibia shaft is vertically installed in the fuselage, and the upper and lower ends are rotatably connected to the cover and the bottom plate of the fuselage respectively, the tibia is fixed on the tibia shaft, one end of the tibia reset spring is fixedly connected to the side wall of the fuselage, and the other end is fixedly connected to the inner wall of the tibia, and the axis of the tibia reset spring is perpendicular to the tibia shaft space; one end of the leg segment passes through the tibia and the leg segment is rotatably connected to the middle part of the tibia, one end of the leg segment reset spring is fixedly connected to one end of the leg segment passing through the tibia, and the other end is fixedly connected to the end ear of the tibia, and the axis of the leg segment reset spring is parallel to the tibia shaft.

3. The shape memory alloy-driven micro hexapod crawling robot according to claim 2, characterized in that: The leg segment comprises a leg segment body; an extension portion is arranged at one end of the leg segment body, the extension portion extends into the tibia, and the middle portion of the extension portion is rotatably connected to the middle portion of the tibia.

4. The shape memory alloy-driven micro hexapod crawling robot according to any one of claims 1 to 3, characterized in that: The internal shape memory alloy wire and the external shape memory alloy wire are made of nickel-titanium alloy.

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