A miniature bidirectional crawling robot based on vibration mode control

Abstract

This invention discloses a miniature bidirectional crawling robot based on vibration mode control, comprising a support frame, a drive device, and a power system. The power system consists of an elastic element, a flexible four-bar linkage, and crawling feet. One end of the elastic element is fixed to the support frame, and the other end is connected to the flexible four-bar linkage. The other end of the flexible four-bar linkage is fixed, with the crawling feet connected in its middle section. The elastic element can generate different vibration modes under different frequency excitations. The drive device can drive the elastic element to undergo forced vibration, which in turn drives the crawling feet relative to the ground through the flexible four-bar linkage to achieve bidirectional crawling. When the power system is in first-order vibration, the robot crawls forward; when the power system is in second-order vibration, the robot crawls backward. Thus, by changing the vibration mode of the elastic element, the robot can be controlled to achieve bidirectional crawling motion. This invention has a simple structure, high reliability, convenient bidirectional motion control, great miniaturization potential, and fast crawling speed.

Description

Technical Field

[0001] This invention relates to the field of microrobot technology, specifically a bidirectional crawling microrobot based on vibration mode control. Background Technology

[0002] Miniature crawling robots are characterized by their small size, agile movement, and high stealth capabilities. During mission execution, thanks to their millimeter-scale micro-size, they can enter confined spaces to carry out tasks such as information collection and detection. They have significant application potential in military and civilian fields such as reconnaissance, surveillance, disaster relief, and damage detection.

[0003] Existing micro-crawling robots have achieved good motion performance in terms of speed, turning radius, and jump height after years of research. However, when a micro-crawling robot accidentally enters a narrow, congested passage and needs to exit, the passage is too narrow and enclosed, preventing the robot from escaping by turning around or jumping, ultimately leaving it trapped until its energy is depleted. Bidirectional crawling capability can effectively solve this problem; the robot can crawl backwards along the trajectory it entered the passage, thus escaping the predicament. Therefore, achieving bidirectional crawling is key to improving the task performance and survivability of micro-robots in unstructured, confined environments. Designing bidirectional crawling capability for micro-crawling robots is of great significance for improving their environmental adaptability and survivability in confined environments.

[0004] Currently, there are two main technical approaches to achieving bidirectional crawling in micro-crawling robots: multi-actuator combination and body structure deformation. For the multi-actuator combination method, one approach is to increase the number of actuators in the micro-crawling robot's power system. By controlling the coupled motion of multiple actuators, the degrees of freedom of the crawling legs are increased, thus enabling forward and backward crawling. The other approach is to set two sets of actuators to drive forward and backward motion respectively, and then combine the forward and backward movements to achieve bidirectional crawling. This multi-actuator combination method inevitably increases the complexity of the system's mechanical structure and reduces its reliability. It also places higher demands on the crawling motion control algorithm and its hardware integration. As for the body structure deformation method, by changing the body structure or leg tilt angle of the unidirectional crawling robot, reverse motion is achieved. This method relies on external adjustments to the robot's mechanical structure, which limits the environmental applicability of its bidirectional crawling function. Summary of the Invention

[0005] To address the shortcomings of existing micro bidirectional crawling robot systems, such as complex integration and control and limited environmental applicability, this invention proposes a micro crawling robot that achieves bidirectional motion control by changing the vibration modes of elastic elements in the power system. This invention greatly simplifies the integration of the drive structure of the micro bidirectional crawling robot, reduces the control difficulty, and eliminates the need for manual modification of the robot structure during the control process, thus significantly improving its adaptability to confined environments.

[0006] The technical solution adopted in this invention is: a miniature bidirectional crawling robot based on vibration mode control, comprising a support frame, a power system and a drive device, wherein the power system consists of elastic elements, a flexible four-bar linkage and crawling legs.

[0007] The support frame provides overall support for the robot. One end of the elastic element is fixed to the support frame, while the other end is a free end connected to a flexible four-bar linkage. The other end of the flexible four-bar linkage is fixed to the support frame, with its middle section connecting the two crawling legs. The drive unit is fixed to the support frame and can drive the free end of the elastic element to reciprocate up and down, causing the elastic element to vibrate under pressure. This, in turn, drives the crawling legs to move forward or backward relative to the ground via the flexible four-bar linkage.

[0008] When the power system is in first-order vibration, the crawling feet are subjected to the resultant force of the ground reaction force forward, and the robot crawls forward; when the power system is in second-order vibration, the crawling feet are subjected to the resultant force of the ground reaction force backward, and the robot crawls backward. Thus, by changing the vibration mode of the elastic element, the robot can be controlled to achieve bidirectional crawling motion.

[0009] Furthermore, the change in the vibration mode of the power system is achieved by adjusting the excitation frequency of the elastic element by the driving device. When the excitation frequency of the driving device on the elastic element is within the range of the first-order vibration frequency of the elastic element, the elastic element is in first-order vibration; when the excitation frequency is within the range of the second-order vibration frequency of the elastic element, the elastic element is in second-order vibration.

[0010] Furthermore, the driving device is an electromagnetic actuator, consisting of a permanent magnet and a coil. The coil is fixed to a support frame, and the permanent magnet is fixed to the free end of the elastic element at a position opposite to the coil. The coil and the permanent magnet are concentrically arranged. When an adjustable alternating current is applied to the coil, an alternating magnetic field and electromagnetic force are generated between the coil and the permanent magnet, thereby driving the elastic element to vibrate under pressure.

[0011] Furthermore, the elastic element is a cantilever beam, spring, or leaf spring, which can generate different vibration modes under different frequency excitations.

[0012] Furthermore, the cantilever beam is made of a flexible metal or composite material, such as carbon fiber, steel, or polyimide.

[0013] Furthermore, the cantilever beam is a sheet-like, filament-like, or a combination of filament-like and sheet-like structures.

[0014] Furthermore, the first and second resonant frequencies of the cantilever beam are determined by the cantilever beam material and its geometry.

[0015] Furthermore, the electromagnetic driver is powered by alternating current with a variable frequency.

[0016] Furthermore, the reaction force exerted by the ground on the crawling feet during the crawling motion of the micro crawling robot is generated by the collision and compression motion of the crawling feet relative to the ground.

[0017] Furthermore, the number of elastic elements, flexible four-bar linkages, and crawling legs in the power system can be set to one or more, and when multiple are set, they can be in series, parallel, or a combination of series and parallel.

[0018] Furthermore, the power system can be one or more sets, and when multiple sets are set, they can be configured in series, parallel or series-parallel combination.

[0019] The advantages of this invention compared to existing technologies are:

[0020] (1) Simple structure and high reliability. In this invention, the robot crawling foot only needs one linear actuator to achieve bidirectional crawling forward and backward, without the need for multiple actuators. The mechanical mechanism is simple and the system has high reliability.

[0021] (2) Convenient bidirectional motion control. The miniature crawling robot of the present invention can control forward and backward movement by changing the vibration mode of the cantilever beam. Since the vibration mode of the cantilever beam changes with the excitation frequency when it is subjected to forced vibration, and the change of the excitation frequency can be easily controlled by microcontroller programming, the robot of the present invention only needs to control the excitation frequency of the cantilever beam to control it to work in the first or second order vibration mode, thereby enabling the robot to crawl forward or backward. Therefore, the bidirectional crawling control of the robot is easy and simplifies the robot's control unit.

[0022] (3) Great potential for miniaturization. In this invention, the power system consists of a cantilever beam, magnets, coils, a flexible four-bar linkage and crawling legs. Since the robot's power system and motion control are simple, each component can be miniaturized to a smaller size, so there is a large space for further miniaturization of the robot.

[0023] (4) Fast crawling speed. When the micro crawling robot of the present invention is working with a power cord, its forward and backward crawling speeds can reach up to 38 times its body length / second and 44 times its body length / second, respectively. In contrast, the crawling speed of existing crawling robots of the same size with power cords is generally less than 10 times its body length / second. It can be seen that the robot of the present invention has a faster crawling speed. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the overall structure of the present invention, wherein Figure 1(a) is an isometric view and Figure 1(b) is an exploded view;

[0025] Figure 2 is a schematic diagram of the power system structure of the present invention, wherein Figure 2(a) is a schematic diagram of the flexible four-bar linkage structure and Figure 2(b) is a schematic diagram of the power system structure;

[0026] Figure 3 is a schematic diagram of the forces acting on the crawling foot during movement. Figure 3(a) is a schematic diagram of the forces acting on the crawling foot moving forward under the first-order vibration of the cantilever beam, and Figure 3(b) is a schematic diagram of the forces acting on the crawling foot moving backward under the second-order vibration of the cantilever beam. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings, using an embodiment that employs a cantilever beam as an elastic element.

[0028] This invention provides a miniature bidirectional crawling robot based on vibration mode control, as shown in Figures 1(a) and 1(b). The support frame 3 provides overall support for the robot and consists of a top plate, side plates, a front plate (right side in the figure), and a rear plate (left side in the figure). A power supply 1 and a power circuit board 2 are fixed to the outer side of the top plate, and a coil 5 is fixed to the inner side of the top plate. The fixed end 41 of the cantilever beam 4 is fixedly connected to the rear plate, and a permanent magnet 7 is fixed to the upper surface of its free end 42. The permanent magnet 7 and the coil 5 are concentrically arranged. The end of the free end 42 of the cantilever beam is connected to the input end of a flexible four-bar linkage 6. The other end of the flexible four-bar linkage 6 is fixed to the front plate of the support frame 3. The middle section of the flexible four-bar linkage 6 connects to two crawling feet 8 (in this example, the flexible four-bar linkage 6 and the crawling feet 8 are integrally formed). Support legs 9 are also connected to the extended section of the rear plate of the support frame 3. After the robot is assembled, the body support frame 3 has an angle of 5° to 20° with the horizontal ground.

[0029] The input end of the power circuit board 2 is connected to the power supply 1, and the output end is connected to the coil 5. The power circuit board 2 can convert the DC power output by the power supply 1 (in this example, a battery) into an AC signal with adjustable frequency. When AC power is applied to the coil 5, an alternating magnetic field and electromagnetic force are generated between it and the permanent magnet 7. The cantilever beam 4 is forced to vibrate under the action of the permanent magnet 7, and then the flexible four-bar linkage 6 drives the crawling foot 8 to collide and squeeze relative to the ground, ultimately enabling the robot to achieve forward and backward crawling movements due to the reaction force of the ground.

[0030] The structural principle of the power system of the present invention is shown in Figure 2(a) and Figure 2(b). The flexible four-bar linkage 6 is a single-degree-of-freedom mechanism. Its input end vibrates up and down under the drive of the cantilever beam, and its output is the rotation of the middle section, thereby driving the crawling foot 8 to collide and squeeze relative to the ground.

[0031] The motions of the crawling feet 8 corresponding to the first and second mode vibrations of the cantilever beam 4 are shown in Figures 3(a) and 3(b). The robot's power system motion is driven by the linear vibration of the permanent magnet 7, and the flexible four-bar linkage 6 converts the linear motion input from the free end 42 of the cantilever beam 4 into the rotation of the crawling feet 8. When the cantilever beam 4 is in the first mode vibration, the vibration of the actuator is converted into a large-amplitude flapping motion of the crawling feet 8 through the flexible four-bar linkage 6. During the counterclockwise rotation of the crawling feet 8, the front legs leave the ground, while during the clockwise acceleration of the crawling feet 8 and the collision and compression motion with the ground, the ground generates a forward reaction force on the robot body, thereby causing the robot to crawl forward. When the cantilever beam 4 is in the second mode vibration, the crawling feet 8 produce a rotation opposite to that in the first mode vibration. Since the amplitude of the actuator vibration in the second mode vibration is much lower than that in the first mode vibration, and the relative collision speed between the crawling feet 8 and the ground is also greatly reduced, the friction force generated by the mutual compression between the crawling feet 8 and the ground is the main source of the crawling driving force. When crawling leg 8 rotates clockwise, it collides with the ground and generates a weak forward crawling force. Then, crawling leg 8 rotates counterclockwise and generates greater compression and friction with the ground. This causes the resultant frictional force generated by crawling leg 8 in one cycle to move backward, thus causing the robot to move backward.

[0032] It should be noted that the first and second resonant frequencies of the elastic element in this invention are determined by its material and geometric dimensions. In this example, the cantilever beam 4 is a sheet structure made of carbon fiber plate, with a length of 13mm, a width of 8mm, and a thickness of 0.15mm. The first resonant frequency of the cantilever beam 4 is 139Hz, and the second resonant frequency is 562Hz. Furthermore, in this embodiment, AC power is output from a battery in conjunction with a power circuit board; however, other forms of power supply are also possible, such as those with power cords and a microcontroller. The support leg 9 can be fixedly connected to the rear plate of the support frame 3, or it can be fixedly connected to the side plate of the support frame 3, or it can be integrally formed.

[0033] All the above descriptions involving orientation, such as top, side, upper, lower, front, and rear, are based on the directions and positional relationships shown in the attached drawings and are for ease of description only, and do not indicate or imply that the parts involved must have a specific orientation, structure, or operation.

[0034] The techniques not described in detail in this invention are well-known in the field.

[0035] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the principles and technical essence of the present invention shall still fall within the scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A miniature bidirectional crawling robot based on vibration mode control, comprising a support frame, a power system, and a drive device, characterized in that: The support frame (3) provides overall support for the robot; The power system consists of an elastic element, a flexible four-bar linkage (6), and crawling feet (8). One end of the elastic element is fixed on the support frame (3), and the other end is a free end. The free end is connected to the flexible four-bar linkage (6). The elastic element can generate different vibration modes under different frequency excitations. The other end of the flexible four-bar linkage (6) is fixed on the support frame (3), and its middle section connects the two crawling feet (8). The driving device is an electromagnetic actuator, consisting of a permanent magnet (7) and a coil (5). The coil (5) is fixed on the support frame (3), and the permanent magnet (7) is fixed on the free end of the elastic element. The coil (5) and the permanent magnet (7) are concentrically arranged. After applying an adjustable alternating current to the coil (5), an alternating magnetic field and electromagnetic force are generated between the coil (5) and the permanent magnet (7), thereby driving the elastic element to vibrate under pressure. Then, through the flexible four-bar linkage (6), the crawling foot (8) is driven to move forward or backward relative to the ground. By adjusting the excitation frequency of the elastic element by the drive device, the vibration mode of the elastic element can be changed, and the robot can be controlled to achieve bidirectional crawling motion: when the power system is in the first order vibration, the crawling foot (8) is subjected to the reaction force of the ground and moves forward, and the robot crawls forward; when the power system is in the second order vibration, the crawling foot (8) is subjected to the reaction force of the ground and moves backward, and the robot crawls backward.

2. The miniature bidirectional crawling robot based on vibration mode control as described in claim 1, characterized in that, The electromagnetic driver is provided with a frequency-adjustable AC signal by a power supply (1) and a power circuit board (2).

3. The miniature bidirectional crawling robot based on vibration mode control as described in claim 1, characterized in that, The elastic element is a cantilever beam (4), a spring, or a leaf spring.

4. The miniature bidirectional crawling robot based on vibration mode control as described in claim 3, characterized in that, The material of the cantilever beam (4) is a metal or composite material with a certain degree of elasticity.

5. The miniature bidirectional crawling robot based on vibration mode control as described in claim 3, characterized in that, The cantilever beam (4) is a sheet-like, filament-like, or a combination of filament-like and sheet-like structures.

6. The miniature bidirectional crawling robot based on vibration mode control as described in claim 1, characterized in that, The reaction force of the ground on the crawling foot (8) during the crawling motion of the micro bidirectional crawling robot is generated by the collision and squeezing motion of the crawling foot (8) relative to the ground.

7. The miniature bidirectional crawling robot based on vibration mode control as described in claim 1, characterized in that, The number of the elastic element, the flexible four-bar linkage (6) and the crawling foot (8) can be set to one or more, and when multiple are set, they can be connected in series, in parallel or in a series-parallel combination.

8. The miniature bidirectional crawling robot based on vibration mode control as described in claim 1, characterized in that, The power system can be one or more sets, and when multiple sets are set, they can be connected in series, parallel or series-parallel combination.

9. The miniature bidirectional crawling robot based on vibration mode control as described in claim 4, characterized in that, The metal with a certain degree of elasticity is stainless steel.

10. The micro bidirectional crawling robot based on vibration mode control as described in claim 4, characterized in that, The composite material with a certain degree of elasticity is carbon fiber or polyimide.

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