Electromagnetism and shape memory alloy hybrid driven multi-gait micro-robot

Abstract

The invention relates to an electromagnet and shape memory alloy hybrid driven multi-gait micro-robot which comprises a main body frame, a cantilever beam electromagnetic driving structure, a front leg assembly and a rear leg assembly are installed on the main body frame, the front leg assembly comprises a single leg unit with a limiting patella and a flexible joint, and an electromagnetic driver drives the front leg assembly to swing periodically; the rear legs deform through power-on and power-off of the shape memory alloy strips, the elevation angle of the robot body is adjusted, the robot can switch gaits, namely, when the terrain is flat, the alloy strips are bent, electromagnetic drive excites resonance, and high-frequency running of the front legs is achieved; the robot can be controlled in an off-line mode, the problem that the speed and obstacle crossing of an existing micro-robot are difficult to consider at the same time is solved, and the robot is suitable for complex terrains such as flat ground and tiny steps.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro robots, in particular to a multi-gait micro robot driven by electromagnetic and shape memory alloy, which can switch between high-frequency running and obstacle-crossing gaits. BACKGROUND

[0002] The development of micro crawling robots highly depends on the progress of driving principles and motion gait bionics. In terms of driving, linear electromagnetic drive, shape memory alloy drive, piezoelectric drive and other ways have been deeply researched and applied. Among them, linear electromagnetic drive can produce high-frequency reciprocating motion or vibration through alternating magnetic field, has the characteristics of simple structure, rapid response, large output force and easy miniaturization, and is often used to realize high-speed motion of micro crawling robots; shape memory alloy drive relies on its thermal phase change effect and excellent size integrability, and shows unique advantages in driving flexible structures; piezoelectric drive is good at high-frequency response and high-precision control.

[0003] In terms of motion gait, researchers have developed various gait modes such as peristaltic gait, alternating tripod walking gait, running gait, etc. by imitating the motion mode of creatures in nature. In particular, the running gait inspired by mammalian running achieves rapid movement through high-frequency and small-amplitude leg movement, and has become an effective scheme to realize high-speed motion of micro robots.

[0004] Considering that there are flat ground, rough surface, step obstacles and other terrains in the actual application environment, micro robots need to have the ability to balance speed and obstacle crossing. Currently, mobile robots of traditional size have been relatively mature, and mostly use motor drive and wheel movement. However, as the size decreases to the order of centimeters or even millimeters, motor drive and wheel movement both face the problem of miniaturization. The existing micro robot scheme using new type of drive and foot crawling has obvious limitations in complex terrain adaptability.

[0005] In terms of driving, a single driving mode cannot meet the needs of high-speed driving and gait adjustment: electromagnetic drive has fast response speed but limited output deformation; shape memory alloy drive can achieve large deformation but has slow response; piezoelectric drive has insufficient driving force, needs high-voltage power supply and other problems.

[0006] In the aspect of motion gait, the existing solutions are difficult to meet the requirements of speed and obstacle crossing at the same time: the running gait can achieve high-speed movement but has insufficient motion stability in obstacle environment, such as the prior patent applications CN115384653A and CN109398528A of the applicant; the peristaltic gait has strong obstacle crossing ability but slow movement speed, such as the prior patent application CN118770413A of the applicant; the alternating tripod walking gait has good stability but is also difficult to balance speed and obstacle crossing ability. The existing technology lacks a comprehensive solution that can effectively adapt to different terrains. SUMMARY

[0007] In view of the technical problem that the existing micro robot is difficult to cross obstacles, the present application provides a multi-gait micro robot driven by electromagnetic and shape memory alloy, which comprises a main frame, a driving assembly, a front leg assembly and a rear leg assembly, the driving assembly, the front leg assembly and the rear leg assembly are all installed on the main frame, the front leg assembly is located on the front side of the main frame and comprises a swing joint and can swing in the front-rear direction; the driving assembly can drive the swing joint to make the front leg assembly swing forward and backward, and the rear leg assembly is installed on the rear side of the main frame and comprises a shape memory alloy strip, the shape memory alloy strip can switch between the unfolded and bent states under the action of electric current, wherein when the multi-gait micro robot switches between different gaits, the attitude of the multi-gait micro robot is adjusted by the deformation of the shape memory alloy strip.

[0008] The present application realizes the complementation and maximum efficiency of the driving function through the mixed driving design of the front leg driving assembly and the rear leg shape memory alloy strip. The front leg driving assembly can provide high-frequency reciprocating power to meet the demand for rapid response and stable output force for high-speed movement of the robot; the rear leg shape memory alloy strip realizes accurate adjustment of the attitude of the robot body by switching the shape under the control of electric current, which makes up for the defects of single electromagnetic driving output deformation limitation and inability to adjust the attitude, or single shape memory alloy driving slow response and difficulty in providing high-frequency propulsion. The cooperation of the two makes the robot have high-efficiency power output and flexible attitude adjustment ability at the same time.

[0009] Preferably, the driving assembly is a cantilever beam electromagnetic driving structure, which specifically comprises an electromagnetic structure arranged between the main frame and the cantilever of the cantilever beam, and the cantilever beam is fixed on the main frame; wherein the electromagnetic structure comprises a coil and a permanent magnet matched with each other.

[0010] When the control circuit inputs alternating current to the coil, the coil quickly generates a periodically changing magnetic field, and the permanent magnet can produce high-frequency reciprocating vibration under the action of the magnetic field force, which is directly transmitted to the swing joint through the cantilever beam and converted into periodic swing power of the front leg assembly.

[0011] Preferably, one end of the shape memory alloy strip is fixed on the main frame, and the other end is placed on the support surface. After the shape memory alloy strip is heated by electricity, it can be stretched out and adjust the body angle of the multi-gait micro robot. The shape memory alloy strip is in a bent state after cooling or without electricity, providing a fulcrum for the back side of the multi-gait micro robot.

[0012] On flat terrain, the alloy strip remains in a bent support state, the body maintains a low angle, and the front end is slightly higher than the rear end. This posture can shorten the swing trajectory radius of the front leg assembly, cooperate with the high-frequency vibration of the cantilever beam electromagnetic drive, and make the front leg swing with "small amplitude and high frequency", reduce air resistance and ground friction loss, and significantly improve the movement speed. At the same time, the bent alloy strip provides stable rear support to prevent the body from lifting or falling when moving at high frequency, ensuring the stability of high-speed movement; when encountering obstacles, the alloy strip is heated to stretch and lift the body angle, synchronously driving the swing starting point of the front leg assembly to rise, and after the front leg increases the height from the ground, it can easily cross the obstacles such as fine steps and cables, avoiding the problem of "front leg knocking obstacles and unable to attach" in the traditional low angle. The adjustment of the angle and the swing of the front leg form a linkage, and after the angle increases, the probability of the front leg attaching to the upper surface of the obstacle increases.

[0013] Preferably, the front leg assembly includes at least one single leg unit, which includes an upper leg, a flexible connection, and a lower leg in sequence. When the lower leg encounters an obstacle, the flexible connection allows the lower leg to bend to the rear side.

[0014] When the robot is in the obstacle climbing mode, the lower leg contacts the obstacle first. The flexible connection deforms elastically due to external force, allowing the lower leg to bend to the rear side. This process not only avoids the rigid collision of the lower leg with the obstacle, but also adjusts the leg force direction through the bending action, converts the impact force into the upward lifting power of the lower leg, changes the leg trajectory from horizontal collision to upward crossing, and significantly improves the probability of the front leg attaching to the upper surface of the obstacle.

[0015] Preferably, the flexible connection has elasticity, and when the lower leg bends to the rear side, the lower leg returns to a straight state relative to the upper leg when the external force disappears.

[0016] When climbing obstacles, the lower leg bends and deforms elastically after contacting the obstacle, absorbing the impact. When the robot moves forward by the swing of the front leg, the lower leg disengages from the obstacle, or the external force disappears, the elasticity of the flexible connection automatically restores the lower leg to a straight state. This resetting action prepares for the leg support in the next front leg attachment or rear leg traction stage.

[0017] Preferably, a position between the upper leg and the lower leg is also provided with a limiting patella, which can prevent the lower leg from bending to the front side. The position of the limiting patella corresponds to that of the flexible connection.

[0018] During high-frequency running gait, the forelegs need to propel the fuselage forward through the ground reaction force generated by the backward swing. At this time, after the lower leg contacts the ground, if there is no patellar restraint, the flexible connection may bend forward due to the forward thrust, causing the ground reaction force to be dispersed. Some of the force is converted into leg deformation energy and cannot be efficiently transmitted to the main frame. Therefore, the patellar restraint prevents the lower leg from bending forward, thus creating a directional power transmission path for the foreleg assembly that provides rigid support for forward thrust and flexible force relief for backward bending.

[0019] Preferably, one end of the patella is fixed to the upper leg, and the other end is connected to the lower leg for a limiting connection; or, one end of the patella is fixed to the lower leg, and the other end is connected to the upper leg for a limiting connection.

[0020] Both solutions do not require additional complex connectors such as screws or clips; the limiting function can be achieved simply by fixing and overlapping.

[0021] Preferably, the front leg assembly includes at least two single-leg units, left and right, with swing joints simultaneously connected to the upper leg drive of both single-leg units. High-frequency reciprocating vibrations are transmitted to the front leg assembly via the swing joints, enabling the left and right single-leg units to swing synchronously at high frequency, thus improving synchronicity.

[0022] Preferably, the front end of the multi-gait microrobot is higher than the rear end, meaning there is an elevation angle between the body and the support surface.

[0023] On flat terrain, the fuselage maintains a low pitch angle, with the front end slightly higher than the rear end. This posture allows the swing trajectory of the front leg components to be closer to the ground, and the swing amplitude does not need to be too large to achieve effective propulsion. Obstacle crossing and climbing gait adaptation: When encountering an obstacle, the shape memory alloy strip of the rear leg is energized and unfolds, further increasing the fuselage pitch angle and raising the front end height. This simultaneously raises the starting height of the front leg swing, allowing the lower front leg to easily cross obstacles such as small steps and cables during the swing, greatly increasing the probability of the front leg grabbing the upper surface of the obstacle.

[0024] Other beneficial effects of the present invention will be described one by one in the following specific embodiments. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the multi-gait microrobot in this invention; Figure 2 This is another overall structural diagram of the multi-gait microrobot in this invention; Figure 3 yes Figure 2 A three-dimensional schematic diagram after removing part of the frame panel; Figure 4 This is a schematic diagram of the straight state structure of a single leg unit of the front leg assembly in this invention; Figure 5 This is a schematic diagram of the single-leg unit bending state structure of the front leg assembly in this invention; Figure 6 is a top view of the multi-gait micro robot in the present application; Figure 7 is an A-A view of Figure 6 ; Figure 8 is a schematic diagram of the motion decomposition process of the high-frequency running of the multi-gait micro robot; Figure 9 is a schematic diagram of the motion decomposition process of the obstacle climbing of the multi-gait micro robot.

[0026] In the figure: 1 main frame; 2 coil; 3 permanent magnet; 4 cantilever beam; 5 swing joint; 6 foreleg assembly; 7 shape memory alloy strip; 8 hind leg; 9 limit patella; 10 upper leg; 11 flexible connection; 12 lower leg. DETAILED DESCRIPTION

[0027] The foregoing and other technical content features and effects of the present application will be described in detail below with reference to the accompanying drawings. Figures 1 to 9 The embodiments are described in detail. The multi-gait micro robot provided by the embodiment adopts a fore-aft foot configuration, and the core bearing structure is a main frame 1. The driving assembly, the foreleg assembly 6, and the hind leg assembly are all integrated and installed on the main frame 1, forming a compact integrated structure. The multi-gait micro robot can be operated with a wire, or the on-board control circuit and power module can be embedded in the main frame 1 to realize off-line controllable motion. The gait switching and motion control can be completed through remote instructions, breaking through the limitation of wired connection on the operation range.

[0028] The robot provides propulsion through the periodic swing of the foreleg assembly 6, and the hind leg assembly adjusts the posture of the robot body through morphological transformation. The two work together to realize the two core gaits of high-frequency running and obstacle climbing, effectively solving the technical pain point that existing micro robots are difficult to balance speed and obstacle climbing ability, and adapting to various complex terrains such as flat ground, slight steps, and cables. Cantilever beam electromagnetic drive structure and foreleg assembly The driving assembly of the multi-gait micro robot can adopt a cantilever beam electromagnetic driving structure, which is the core power source for realizing the high-frequency swing of the front legs. Specifically, the structure includes a coil 2, a permanent magnet 3, and a cantilever beam 4. The cantilever beam 4 is fixedly connected to the main frame 1, and the electromagnetic structure formed by the coil 2 and the permanent magnet 3 is arranged between the main frame 1 and the cantilever of the cantilever beam 4, forming a precise electromagnetic coupling relationship. When the control circuit inputs an alternating current to the coil 2, the coil 2 generates a periodically changing alternating magnetic field, and the permanent magnet 3 undergoes high-frequency reciprocating vibration under the action of the magnetic field force. This vibration is transmitted to the swing joint 5 through the cantilever beam 4. With the elastic properties of the cantilever beam and the high-frequency response of the electromagnetic structure, efficient transmission of vibration energy is achieved, and electromagnetic energy is converted into periodic swing power for the front leg assembly 6. This structure has the characteristics of rapid response, large output force, and good miniaturization adaptability, providing core power support for the high-frequency running gait of the robot and overcoming the defects of insufficient driving force of piezoelectric driving and slow response of shape memory alloy driving.

[0029] The front leg assembly 6 is symmetrically arranged on the front side of the main frame 1 and includes at least two single leg units. The swing joint 5 is connected to the upper leg driving of the two single leg units, ensuring the synchronization of the movement of the two single leg units.

[0030] The cantilever beam electromagnetic driving structure and swing joint 5 described above are prior art, which can be referred to in the applicant's prior application patents CN115384653A and CN109398528A. The specific technical details are not repeated.

[0031] In the front leg assembly, a flexible joint is introduced. Each single leg unit is sequentially provided with an upper leg 10, a flexible connection 11, and a lower leg 12 from top to bottom. The flexible connection 11 has elastic recovery properties, and a limiting patella 9 is arranged at the corresponding position to form a one-way rotating joint structure. The limiting patella 9 can be installed in two ways: one end is fixed with the upper leg 10, and the other end is limited to overlap with the lower leg 12; the other end is fixed with the lower leg 12, and the other end is limited to overlap with the upper leg 10. Both schemes can realize one-way constraint of the lower leg 12, i.e., prevent it from bending forward, while allowing it to bend backward.

[0032] In terms of materials, the upper leg 10 and the lower leg 12 of the single leg unit can both adopt a whole formed by hot pressing multiple carbon fiber layers with a hot melt adhesive film, and a polyimide film is used at the flexible connection 11. The limiting patella 9 can be an extension plate of the carbon fiber plate of the upper leg 10 or the lower leg 12.

[0033] This structural design enables a passive adaptive function. When the robot encounters an obstacle, the lower leg 12 collides with the obstacle, and the flexible connection 11 undergoes elastic deformation, causing the lower leg 12 to bend backward. This absorbs the impact force while increasing the effective lifting height of the leg, creating conditions for obstacle-crossing. When the leg contacts the ground, the limiting patella 9 plays a limiting role, restricting the forward displacement of the lower leg 12 and keeping the flexible connection 11 rigid. This ensures that the ground reaction force is efficiently converted into the robot's forward propulsion force, achieving a synergistic balance between high-speed movement and obstacle-crossing ability. Hind leg components The rear leg assembly is mounted on the rear side of the main frame 1. Its core driving element is a shape memory alloy strip 7, one end of which is fixedly connected to the main frame 1, while the other end naturally rests on the support surface, forming a support fulcrum at the rear of the robot. The shape memory alloy strip 7 possesses thermotropic phase change characteristics, allowing for precise control of power on / off via a control circuit, enabling reversible switching between extended and bent states. When not powered or cooled, the shape memory alloy strip 7 is in a bent state, providing a stable support fulcrum for the robot body and ensuring posture stability during movement. When powered and heated, the shape memory alloy strip 7 undergoes a phase change and extends, pushing the rear end of the main frame 1 downwards through shape change, thereby adjusting the robot's tilt angle. This assembly complements the front leg assembly 6, providing a suitable body posture for different states through tilt angle adjustment, solving the technical challenge of a single driving method being unable to simultaneously handle power output and posture adjustment. When using 1) such as Figure 8 As shown, when the robot is on a flat support surface, the system switches to a high-frequency running gait, with all structures working together to achieve high-speed movement. At this time, the control circuit controls the shape memory alloy strip 7 of the rear leg assembly to remain in an unenergized state, i.e., a bent state, providing a stable support point for the body and maintaining a stable posture with a low elevation angle. Simultaneously, the coil 2 of the cantilever beam electromagnetic drive structure is controlled to receive an alternating current of a specific frequency, which matches the system's first-order natural frequency, exciting the mechanical resonance between the permanent magnet 3 and the cantilever beam 4. This high-frequency reciprocating vibration is transmitted to the front leg assembly 6 through the swing joint 5, causing the two single-leg units on the left and right to synchronously perform high-frequency periodic swinging. During the swinging motion, the patella 9 of the front leg assembly restricts the lower leg 12 from bending forward, while the flexible connection 11 remains rigid, ensuring that the ground reaction force is efficiently transmitted to the main frame 1 and converted into forward propulsion. In this mode, the high-frequency response characteristics of electromagnetic drive combined with the resonant amplification effect enable high-speed movement of the microrobot. Compared with existing peristaltic gait and alternating tripod gait, the movement speed is significantly improved. At the same time, the stable support of the hind legs and the rigid transmission of the front legs ensure the stability of high-speed movement. 2) such as Figure 9As shown, when the robot detects subtle steps, cables and other discrete obstacles, the system automatically switches to an obstacle climbing gait, which is completed by the coordinated action chain of the front leg assembly and the rear leg assembly, and specifically divided into four stages: (1) The elevation angle adjustment stage, the control circuit applies a driving signal to the shape memory alloy strip 7 of the rear leg assembly, so that it is heated and partially expanded (not fully expanded), pushing the main body frame 1 to lift, increasing the body elevation angle, thereby increasing the ground clearance when the front leg assembly 6 swings, significantly increasing the probability of the front leg attaching to the surface of the obstacle. (2) The front leg attachment stage, control the cantilever beam electromagnetic drive structure to reduce the current frequency of the coil 2, so that the front leg assembly 6 swings forward and backward at a lower frequency, and the robot body is slowly moved forward through the precise attachment action of the front leg, until the front leg successfully attaches to the higher surface of the obstacle, and the main body frame 1 is completely migrated to the top of the obstacle. (3) The rear leg traction stage, increase the driving signal of the shape memory alloy strip 7, so that it is fully powered and expanded, and the rear leg is completely separated from the ground, also preventing the rear leg from hooking the edge of the obstacle during climbing. At this time, control the front leg assembly 6 to continue to swing, and use the propulsion force of the front leg to pull the rear leg to the top of the obstacle, completing the overall obstacle migration of the body. (4) The posture recovery stage, when the robot projection surface is completely located on the surface of the obstacle, it is considered that the obstacle climbing is completed, and the shape memory alloy strip 7 is controlled to be powered off and cooled, so that it returns to the curved state and falls down, and a stable support structure is reformed, preparing for subsequent movement or gait switching. This mode adjusts the elevation angle through the staged deformation of the shape memory alloy strip, and cooperates with the frequency adaptation swing of the front leg, realizing stable and efficient obstacle climbing action, and solving the technical defects of insufficient obstacle climbing stability of the existing running gait. The core operation logic of the multi-gait micro robot is based on the cooperative mechanism of "hybrid drive + posture adaptation + gait switching". At the drive level, a hybrid configuration of cantilever beam electromagnetic drive and shape memory alloy drive is adopted. The electromagnetic drive of the front leg provides rapid response and large output force, providing the core propulsion force required for high-speed movement and obstacle climbing; the shape memory alloy drive of the rear leg utilizes its large deformation characteristics to realize precise adjustment of the body elevation angle, and the two functions are complementary, breaking through the performance limitations of single drive mode.

[0034] At the structure coordination level, the one-way rotating joint of the front leg assembly realizes flexible force relief when hitting obstacles and rigid propulsion when contacting the ground through the cooperation of the limiting patella 9 and the flexible connection 11, solving the contradiction between speed and obstacle climbing ability; the shape memory alloy strip 7 of the rear leg assembly switches between on and off states to provide an adaptive body posture for different gaits, so that the low elevation angle stability required by high-frequency running and the high elevation angle attachment ability required by obstacle climbing form a precise match. At the control level, the robot can complete the switching of two gaits according to different terrains, and realize the coordinated action of each structure by adjusting the electromagnetic drive frequency and the drive signal strength of the shape memory alloy strip. During the overall operation, each component closely cooperates, so that the robot has the high-speed movement and active obstacle-crossing ability in the off-line state, and the applicability of the micro robot in the complex environment is significantly improved.

[0035] The above is only for the purpose of illustrating the present application, and it should be understood that the present application is not limited to the above examples, and various modifications in accordance with the idea of the present application are within the scope of the present application.

Claims

1. A multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy, comprising a main frame (1), a drive assembly, a front leg assembly (6), and a rear leg assembly all mounted on the main frame (1), characterized in that: The front leg assembly (6) is located on the front side of the main frame (1), and the front leg assembly (6) includes a swing joint (5) and is capable of swinging in the front-back direction; The drive component, which drives the swing joint (5), thereby causing the front leg assembly to swing back and forth, The rear leg assembly is installed on the rear side of the main frame (1), and includes a shape memory alloy strip (7), which can switch between unfolded and bent states under the action of an electric current. Among them, when the multi-gait microrobot switches between different gaits, the elevation angle of the multi-gait microrobot is adjusted by the deformation of the shape memory alloy strip.

2. The multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy according to claim 1, characterized in that: The drive assembly is a cantilever beam electromagnetic drive structure, specifically including: An electromagnetic structure is set between the main frame (1) and the cantilever beam (4), which is fixed on the main frame (1); wherein the electromagnetic structure includes a coil (2) and a permanent magnet (3) that cooperate with each other.

3. The multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy according to claim 1, characterized in that: One end of the shape memory alloy strip is fixed on the main frame (1), and the other end is placed on the support surface. The shape memory alloy strip (7) can be extended after being heated by electricity and adjust the body elevation angle of the multi-step micro robot. The shape memory alloy strip is in a bent state after cooling or when not powered on, providing a fulcrum for the rear of the multi-step micro robot.

4. The multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy according to claim 1, characterized in that: The front leg assembly (6) includes at least one single-leg unit, which includes an upper leg (10), a flexible connection (11) and a lower leg (12) in sequence. When the lower leg encounters an obstacle, the flexible connection allows the lower leg to bend backward.

5. A multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy according to claim 4, characterized in that: The flexible connection is elastic. When the lower leg is bent backward, it returns to a straight position relative to the upper leg when the external force is removed.

6. A multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy according to claim 4, characterized in that: A limiting patella (9) is provided between the upper leg (10) and the lower leg (12) to prevent the lower leg from bending forward. The limiting patella is positioned corresponding to the flexible connection.

7. A multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy according to claim 4, characterized in that: One end of the limiting patella (9) is fixed to the upper leg (10), and the other end is limited and overlapped with the lower leg (12); or, one end of the limiting patella (9) is fixed to the lower leg (12), and the other end is limited and overlapped with the upper leg.

8. A multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy according to claim 4, characterized in that: The front leg assembly includes at least two single-leg units, one on the left and one on the right, with the swing joint simultaneously connected to the upper leg drive of both single-leg units.

9. A multi-gait microrobot driven by a hybrid electromagnetic and shape memory alloy according to claim 1, characterized in that: The front end of the multi-gait microrobot is higher than the rear end, meaning there is an elevation angle between the body and the supporting surface.

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