Multistable robotic module

Abstract

Disclosed is a kind of multi-stable robot module, in the module, two first wheel discs are oppositely arranged with interval, the first wheel disc includes a first number of first wheel teeth;First rigid block is located between the two first wheel discs, and the two first wheel discs are symmetrically fixed on the two sides of the first rigid block by fasteners;Second wheel disc is connected with the first wheel disc by the second wheel teeth engaged with the first wheel teeth;The connector is located between the two second wheel discs, and the connector includes an upper second rigid block and a lower third rigid block, the second rigid block and the third rigid block are connected by a pair of parallel flexible thin rods to form a flexible parallelogram mechanism, the first rigid block is hinged to the second rigid block by a pin shaft, the first wheel disc moves multi-stably relative to the second wheel disc, the multi-stable motion is a composite motion of single-degree-of-freedom rotation and reciprocating movement, and the profile of the first wheel tooth and the profile of the second wheel tooth are a pair of conjugate curves of the multi-stable motion.

Description

Technical Field

[0001] This invention relates to the field of robotics, and in particular to a multistable robot module. Background Technology

[0002] In fields such as aerospace, military, and medical rehabilitation, robots are typically required to have flexible and versatile configurations to adapt to complex and changing environments, tasks, and objects being manipulated. Multistable mechanisms can remain stably in multiple working configurations without requiring energy to maintain them, and can also rapidly switch configurations during actuation, making them an effective technical means to realize variable-configuration robots.

[0003] US Patent US-6343788-B1 discloses a multistable device employing a convex polygon combined with an elastic skin. Chinese patents CN201910086093 and CN201910085645 also disclose multistable robot structures using a convex polygon combined with ropes. While these polygonal multistable mechanisms offer advantages such as compact structure and high strength, they still have a drawback. Analyzing the geometric properties of polygons reveals that when the area of ​​a polygon is fixed, the side length decreases as the number of sides increases. This means that as the number of stable configurations of the joints increases, its stiffness, i.e., its load-bearing capacity, continuously decreases. This contradiction between the number of stable configurations and the stable stiffness makes it difficult to balance the variety of variants and load-bearing capacity of variable-configuration robots, thus restricting their widespread application.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a multi-steady-state robot module. The number of steady-state configurations and the steady-state stiffness of this module can be arbitrarily adjusted, and it also has the advantages of simple and reliable structure and low manufacturing cost.

[0006] The objective of this invention is achieved through the following technical solution: a multistable robot module includes,

[0007] Two first discs are arranged opposite each other at a distance, and each first disc includes a first number of first teeth;

[0008] The first rigid block is located between the two first wheel disks, which are symmetrically fixed to both sides of the first rigid block by fasteners.

[0009] Two second discs are arranged opposite each other at a distance, each second disc includes a second number of second teeth, and the second discs are connected to the first disc via second teeth that mesh with the first teeth;

[0010] A connector, located between two second disks, includes a second rigid block located above and a third rigid block located below. The second and third rigid blocks are connected by a pair of parallel flexible rods to form a flexible parallelogram mechanism. The two second disks are symmetrically fixed to both sides of the third rigid block by fasteners. The first rigid block is hinged to the second rigid block via a pin. The first disk performs multistable motion relative to the second disk. The multistable motion is a composite motion of single-degree-of-freedom rotation and reciprocating motion. The profiles of the first and second gear teeth are a pair of conjugate curves of the multistable motion.

[0011] In the multi-stable robot module, the tooth profile of the first gear tooth is a circular arc segment, and the tooth profile of the second gear tooth is an equidistant curve of the trajectory generated by the center of the first gear tooth under multi-stable motion.

[0012] In the aforementioned multi-stable robot module, the second rigid block and the third rigid block have a degree of freedom of movement and simultaneously provide a constraint force to keep the first wheel in contact with the second wheel.

[0013] In the multi-stable robot module, the maximum distance of reciprocating movement in multi-stable motion is the steady-state distance, and the rotation angle accompanying each reciprocating movement is the steady-state angle. The pitch circle radius, the number of first gear teeth, and the radius of the first wheel are determined based on the steady-state distance and the steady-state angle. The center of the pitch circle is the rotation center of the first wheel. The first gear teeth are evenly distributed on the pitch circle, and the angle between adjacent gear teeth is the steady-state angle.

[0014] In the multi-stable robot module, the second tooth generation point is selected on the pitch circle, the trajectory of the generation point is calculated according to the multi-stable motion equation, and the trajectory of the generation point is plotted as an equidistant curve with a distance equal to the radius of the first tooth. The equidistant curve is used as the profile of the second tooth.

[0015] In the aforementioned multi-stable robot module, the first and second gear teeth are corrugated teeth.

[0016] In the aforementioned multi-stable robot module, the first number is twenty-four, and the second number is eleven.

[0017] Compared with existing technologies, the present invention has the following advantages: the number of steady-state configurations and the steady-state stiffness of the present invention can be arbitrarily adjusted without affecting each other. This is because the teeth on the wheel have a corrugated shape, and the designer can change the number of steady-state configurations by adjusting the adjacent angles of the teeth. Simultaneously, the included angles and tooth heights of the corrugated teeth are independent of each other; therefore, the steady-state stiffness can be changed by altering the tooth height while keeping the number of steady-state configurations constant. Furthermore, the present invention can achieve simultaneous meshing of multiple pairs of first and second teeth, effectively dispersing stress. In addition, the wheel of the present invention has a flat plate structure, making it easy to process and reducing manufacturing costs. Attached Figure Description

[0018] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0019] In the attached diagram:

[0020] Figure 1 This is a schematic diagram of the structure of a multistable robot module according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the steady-state transition process of a multi-stable robot module according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of a corrugated toothed multistable wheel of a multistable robot module according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the multistable motion equations of a multistable robot module according to an embodiment of the present invention;

[0024] Figure 5 This is a comparative schematic diagram of the second wave gear teeth with different parameters of a multistable robot module according to an embodiment of the present invention.

[0025] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0026] The following will refer to the appendix. Figures 1 to 5 Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0027] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0028] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0029] To better understand, such as Figures 1 to 5 As shown, the multi-stable robot module includes,

[0030] Two first wheel disks 1 are arranged opposite each other at a distance, and each first wheel disk 1 includes a first number of first wheel teeth 101;

[0031] The first rigid block 4 is located between the two first wheel disks 1, and the two first wheel disks 1 are symmetrically fixed to both sides of the first rigid block 4 by fasteners 6.

[0032] Two second wheel disks 2 are arranged opposite each other at a distance. Each second wheel disk 2 includes a second number of second wheel teeth 201. The second wheel disk 2 is connected to the first wheel disk 1 via the second wheel teeth 201 that mesh with the first wheel teeth 101.

[0033] Connector 3, located between two second wheel disks 2, includes a second rigid block 301 located above and a third rigid block 302 located below. The second rigid block 301 and the third rigid block 302 are connected by a pair of parallel flexible thin rods 303 to form a flexible parallelogram mechanism. The two second wheel disks 2 are symmetrically fixed to both sides of the third rigid block 302 by fasteners 6. The first rigid block 4 is hinged to the second rigid block 301 via a pin 5. The first wheel disk 1 performs multistable motion relative to the second wheel disk 2. The multistable motion is a composite motion of single-degree-of-freedom rotation and reciprocating motion. The profile of the first gear tooth 101 and the profile of the second gear tooth 201 are a pair of conjugate curves of the multistable motion.

[0034] In a preferred embodiment of the multistable robot module, the tooth profile of the first gear tooth 101 is an arc segment, and the tooth profile of the second gear tooth 201 is an equidistant curve of the trajectory generated by the center of the first gear tooth 101 under multistable motion.

[0035] In a preferred embodiment of the multistable robot module, there is a degree of freedom of movement between the second rigid block 301 and the third rigid block 302, and at the same time, a constraint force is provided to keep the first wheel 1 in contact with the second wheel 2.

[0036] In a preferred embodiment of the multi-steady-state robot module, the maximum distance of reciprocating movement in multi-steady-state motion is the steady-state distance, and the rotation angle accompanying each reciprocating movement is the steady-state angle. The pitch circle radius of the first wheel 1 and the number and radius of the first gear teeth 101 are determined based on the steady-state distance and the steady-state angle. The center of the pitch circle is the rotation center of the first wheel 1. The first gear teeth 101 are evenly distributed on the pitch circle, and the angle between adjacent gear teeth is the steady-state angle.

[0037] In a preferred embodiment of the multistable robot module, the second gear tooth origination point is selected on the pitch circle, the trajectory of the origination point is calculated according to the multistable motion equation, and the trajectory of the origination point is plotted as an equidistant curve with a distance equal to the radius of the first gear tooth 101. The equidistant curve is used as the profile of the second gear tooth 201.

[0038] In a preferred embodiment of the multistable robot module, the first gear tooth 101 and the second gear tooth 201 are corrugated teeth.

[0039] In a preferred embodiment of the multistable robot module, the first number is twenty-four and the second number is eleven.

[0040] In one embodiment, the second number is less than the first number.

[0041] In one embodiment, the corrugated toothed multistable robot module includes two first disks 1, two second disks 2, and a connector 3 connecting the first disks and the second disks. The first disks 1 have twenty-four first teeth 101, and the second disks 2 have eleven second teeth 201. The two first disks 1 are symmetrically fixed to a first rigid block 4 by fasteners 6. The first rigid block 4 is hinged to a second rigid block 301 above the connector 3 by pins 5. The two second disks 2 are symmetrically fixed to a third rigid block 302 below the connector 3 by fasteners 6. The second rigid block 301 and the third rigid block 302 are connected by a pair of parallel flexible rods 303, making the connector 3 a flexible parallelogram mechanism.

[0042] like Figure 2As shown, during the steady-state transition process of the corrugated toothed multi-stable robot module, from left to right, the first steady-state configuration, the intermediate state of the steady-state transition process, and the next steady-state configuration are as follows: With the first gear 101 and the second gear 201 tangentially meshing, the first wheel 1 first rotates and moves upward, pushing the flexible link to deform and store energy. Then it continues to rotate and move downward, reducing the deformation of the flexible link 303 and releasing energy, finally falling into the next steady-state configuration. In this new steady-state configuration, the first gear 101 and the second gear 201 remain meshed. Therefore, if the first wheel 1 continues to rotate, it will continue to generate periodic up-and-down movements. While the first wheel 1 is continuously moving up and down, the flexible part of the connector 3 continuously stores and releases elastic energy. Each minimum point of elastic energy corresponds to a steady-state configuration of the robot module; therefore, the robot module has multiple stable states. The combined motion of rotation and reciprocating movement of the first wheel 1 is called multi-steady-state motion. The maximum distance of the reciprocating movement is the steady-state distance S, and the rotation angle accompanying each reciprocating movement is the steady-state angle α.

[0043] like Figure 3 The diagram shows a front view of a pair of corrugated toothed multistable disks. The first corrugated disk 7 has eight first corrugated teeth 701, which in this embodiment are circular arcs. The pitch circle 702 is a virtual circle representing the size of the first corrugated disk 7. The centers of all the first corrugated teeth 701 are located on the pitch circle 702 and are evenly distributed around the pitch circle. The rotation angle between adjacent first corrugated teeth 701 is the steady-state angle α, and the radius of the circular arc tooth is R. a The radius of the pitch circle is R. The second corrugated disk 8 has five corrugated teeth 801. After the first corrugated disk 7 and the second corrugated disk 8 are correctly assembled, the second corrugated teeth 801 can always maintain tangential meshing with the first corrugated teeth 701, constraining the first corrugated disk 7 and the second corrugated disk 8 to produce multistable motion.

[0044] The design method of the multistable disk of the present invention is as follows:

[0045] 1) Select the steady-state angle α and the steady-state distance S, and calculate the multi-steady-state motion equations.

[0046] In this embodiment, let α = 25° and S = 2mm, with the rotation angle as the independent variable and the displacement as the dependent variable. Through piecewise interpolation of a 6th-order spline curve, a multi-stable motion equation with a period of 25° and a displacement range of [0, 2]mm can be obtained. The graph of this equation is shown below. Figure 4 As shown.

[0047] 2) Design the first gear teeth

[0048] The pitch circle radius 702 is selected as R = 25mm. The number of first corrugated teeth 701 is 8, and the first corrugated teeth 701 adopt an arc shape with an arc radius R. a =1mm. It is easy to obtain from these parameters... Figure 3 The first corrugated wheel 7 is shown.

[0049] 3) Calculation of the second gear teeth using the conjugate method

[0050] Select the conjugate tooth profile generation point 703 on the pitch circle 702, and denote it by the letter P.

[0051] Let the first wheel 1 move according to the derived multistable equations. When point P has gone through 5 cycles, we can obtain... Figure 3 Trajectory 704 is used as a guide. Then, draw equidistant curves outwards from trajectory 704, with the equidistant distance equal to the radius R of the arc. a That is, 1mm is enough to obtain the second corrugated gear tooth 801, which consists of 5 corrugations.

[0052] This allows for the design of multi-stable mechanisms with higher or lower steady-state stiffness while maintaining the same number of steady-state configurations. Keeping the pitch circle radius of 702 at 25mm and the steady-state angle at 25°, draw the profiles of two second-wave tooth profiles with steady-state distances of 2.5mm and 1.5mm, as shown below. Figure 5 As shown, the second corrugated tooth profile 802 is generated with a steady-state distance of 2.5 mm, and the second corrugated tooth profile 803 is generated with a steady-state distance of 1.5 mm. It can be seen that, with the same disk size and number of steady-state profiles, the second corrugated tooth profile 802 is significantly larger than the second corrugated tooth profile 803. Therefore, under the same flexible connector constraints, the second corrugated tooth profile 803 will cause greater deformation of the flexible connector, thus exhibiting higher steady-state stiffness.

[0053] In addition, through comparison Figure 1 and Figure 3 The multistable roulette wheel shown is visible. Figure 1 The steady-state angle of the multi-steady-state roulette wheel is 9°, which is less than... Figure 3 The steady-state angle of the multi-steady disk is 25°, therefore, within the same rotation range, Figure 1 Medium-steady-state roulette ratio Figure 3 The multi-stable wheel has a greater number of stable configurations, which suggests that the number of stable configurations of multi-stable joints can be designed by the stable angles.

[0054] In summary, the multistable disk design method of this invention can adjust the number of steady-state configurations by setting the steady-state angle, and can arbitrarily set the steady-state stiffness while keeping the number of steady-state configurations constant. This improves the design flexibility of multistable robot joints. Furthermore, the meshing pattern of multiple pairs of corrugated teeth has a stress averaging effect, ensuring that the joint maintains sufficient strength even when the number of configurations increases and the thickness of individual teeth decreases.

[0055] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.

Claims

1. A multistable robot module, characterized in that, It includes, Two first discs are arranged opposite each other at a distance, and each first disc includes a first number of first teeth; The first rigid block is located between the two first wheel disks, which are symmetrically fixed to both sides of the first rigid block by fasteners. Two second discs are arranged opposite each other at a distance, each second disc includes a second number of second teeth, and the second discs are connected to the first disc via second teeth that mesh with the first teeth; A connector, located between two second disks, includes a second rigid block located above and a third rigid block located below. The second and third rigid blocks are connected by a pair of parallel flexible rods to form a flexible parallelogram mechanism. The two second disks are symmetrically fixed to both sides of the third rigid block by fasteners. The first rigid block is hinged to the second rigid block via a pin. The first disk performs multistable motion relative to the second disk. The multistable motion is a composite motion of single-degree-of-freedom rotation and reciprocating motion. The profiles of the first and second gear teeth are a pair of conjugate curves of the multistable motion.

2. The multi-stable robot module according to claim 1, characterized in that, The tooth profile of the first gear is a circular arc segment, and the tooth profile of the second gear is an equidistant curve of the trajectory generated by the center of the first gear under multiple steady-state motion.

3. The multistable robot module according to claim 1, characterized in that, The second and third rigid blocks have a degree of freedom of movement and simultaneously provide a constraint force to keep the first and second wheels in contact.

4. The multistable robot module according to claim 1, characterized in that, The maximum distance of reciprocating motion in multi-steady-state motion is the steady-state distance, and the rotation angle accompanying each reciprocating motion is the steady-state angle. Based on the steady-state distance and the steady-state angle, the pitch circle radius, the number of first gear teeth, and the radius are determined. The center of the pitch circle is the rotation center of the first gear. The first gear teeth are evenly distributed on the pitch circle, and the angle between adjacent gear teeth is the steady-state angle.

5. The multistable robot module according to claim 4, characterized in that, The second tooth origination point is selected on the pitch circle. The trajectory of the origination point is calculated according to the multi-steady-state motion equation. The trajectory of the origination point is plotted as an equidistant curve with a distance equal to the radius of the first tooth. The equidistant curve is used as the profile of the second tooth.

6. The multistable robot module according to claim 1, characterized in that, The first and second gear teeth are corrugated teeth.

7. The multistable robot module according to claim 1, characterized in that, The first number is twenty-four, and the second number is eleven.

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