Dual-mode deformable wheel-foot robot and wheel-foot-trolley form switching method thereof

Abstract

The invention provides a dual-mode deformable wheel-foot robot and a wheel-foot-trolley form switching method thereof.A robot body (3) of the robot is provided with a leg mechanism, the leg mechanism comprises a chassis containing a wheel-foot component, and the wheel-foot component comprises an auxiliary wheel (6) located at one end of the chassis and further comprises a driving wheel (8) located at the other end of the chassis and used for driving the chassis to run; the chassis is connected with the robot body through a knee joint mechanism, and the knee joint mechanism comprises a connecting rod mechanism connected with the robot body through leg joints. Joint motors are arranged at leg joints, when the robot runs, the chassis is driven by the driving wheels to move, and the posture of the chassis is adjusted by driving a five-connecting-rod mechanism through joint torque output by the joint motors, so that the contact state of the auxiliary wheels and the ground is changed; the advantages of two movement modes of wheel type movement and foot type walking are combined, autonomous switching between a wheel-foot mode and a trolley mode is achieved through the auxiliary wheel mechanism on the rear portion of the knee joint, and the robot belongs to the innovative design of a variable-configuration robot.

Description

Technical Field

[0001] This invention relates to the field of mobile robot technology, and in particular to a dual-mode deformable wheeled robot and its wheeled-cart mode switching method. Background Technology

[0002] Over the past three decades, mobile robots have garnered significant attention due to their suitability for complex environments, space exploration, rescue operations, and tasks performed without human intervention. Based on their mobile devices, they can be categorized into three types: legged robots, wheeled robots, and tracked robots. The motion system is the core of a robot, requiring consideration of factors such as workspace, mobility, controllability, terrain adaptability, and efficiency. Each type of motion system has its own advantages and disadvantages. Legged robots have discrete footholds that can be autonomously chosen, facilitating obstacle crossings and ditch-like obstacles. However, their speed and efficiency are lower than wheeled robots. Tracked robots have a large contact area with the ground, making them suitable for moving on soft and curved terrain. However, their speed and efficiency are also lower than wheeled robots, and their obstacle-crossing ability is inferior to legged robots. Mobile robots using a single locomotion mode each have their own advantages and disadvantages. Hybrid mobile robots, on the other hand, combine the advantages of two or more types of robots while effectively mitigating their respective shortcomings, resulting in superior overall motion performance and broad application prospects. Therefore, they are gradually becoming a popular research topic.

[0003] Legged robots combine the features of wheeled and legged robots, possessing high mobility, flexibility, and strong terrain adaptability, offering improved movement capabilities compared to the three types of robots mentioned above. Among wheeled-legged robots, four-wheeled and two-wheeled robots are common. Two-wheeled robots offer higher flexibility, suitable for movement in confined spaces, but have weaker environmental adaptability. Four-wheeled robots, on the other hand, offer better stability and can maintain system stability when crossing obstacles, exhibiting better environmental adaptability. However, they have lower flexibility and are larger, making them unsuitable for confined spaces. Therefore, multi-mode wheeled-legged robots are gaining attention. These robots, based on two-wheeled robots, add two auxiliary wheels, allowing them to switch between two-wheeled and four-wheeled modes, combining the advantages of both types while maintaining excellent flexibility and strong stability. In-depth research into the key technologies of multi-mode wheeled-legged robots has significant theoretical and practical value.

[0004] However, existing technologies have the following limitations:

[0005] The challenge of balancing energy consumption and stability: Although the wheel-foot mode is highly mobile, maintaining dynamic balance during long-term operation or when bearing heavy loads requires a large amount of energy, resulting in high control complexity.

[0006] Limitations of a single mode: When traditional bipedal robots lower their center of gravity to enhance stability, their legs are often in an ineffective support state, resulting in structural waste; while the pure wheeled vehicle mode loses its obstacle-crossing advantage.

[0007] Insufficient configuration switching capability: The existing robot has a fixed form and lacks the ability to smoothly transition between wheeled and legged form and low center of gravity vehicle form, making it difficult to adapt to the changing needs of the working environment.

[0008] Structural redundancy problem: In order to accommodate two motion modes, robots are often equipped with two independent systems, which leads to structural complexity and increased weight. Summary of the Invention

[0009] This invention proposes a dual-mode deformable wheeled-legged robot and its wheel-leg-vehicle mode switching method, which combines the advantages of wheeled movement and legged walking. The robot achieves autonomous switching between wheel-legged mode and vehicle mode through an auxiliary wheel mechanism behind the knee joint, which is an innovative design of a variable configuration robot.

[0010] The present invention adopts the following technical solution.

[0011] A dual-mode deformable wheeled robot has a robot body (3) with a leg mechanism. The leg mechanism includes a chassis with wheel components. The wheel components include an auxiliary wheel (6) located at one end of the chassis and an active wheel (8) located at the other end of the chassis for driving the chassis. The chassis is connected to the robot body via a knee joint mechanism. The knee joint mechanism includes a linkage mechanism connected to the robot body via the leg joint. A joint motor is provided at the leg joint. When the robot moves, the active wheel drives the chassis to move. The joint torque output by the joint motor drives the five-bar linkage to adjust the chassis posture, thereby changing the contact state between the auxiliary wheel and the ground.

[0012] The drive wheel includes a hub motor structure consisting of a rubber tire and a wheel motor.

[0013] The auxiliary wheel includes a rubber tire; the drive wheel is the front wheel of the chassis.

[0014] The linkage mechanism is used for the retraction and extension of the auxiliary wheels. It is an asymmetric five-bar linkage mechanism that can improve the support performance of the robot's legs and reduce the joint torque output.

[0015] The articulated motor includes a first articulated motor and a second articulated motor. The asymmetric five-bar linkage includes four acrylic links, wherein the second link is a stationary link located at the chassis. All links are manufactured by laser cutting.

[0016] Of the four links, one end of the first link (5) at the robot body is connected to the output end of the first joint motor (4) at the robot body, and the other end is hinged to the auxiliary wheel side of the second link (7) on the chassis. One end of the second link is hinged to the wheel foot motor of the drive wheel.

[0017] One end of the third link (9) is hinged to the second link (preferably, the hinge point can slide at the second link), and the other end is hinged to one end of the fourth link (2) at the robot body. The other end of the fourth link is connected to the output end of the second joint motor (1) at the robot body.

[0018] The asymmetric five-bar linkage employs a double-bearing fixing structure at each hinge point, using flanged deep groove ball bearings to fix the upper and lower ends, with washers separating adjacent links in the middle.

[0019] The asymmetric five-bar linkage uses a locking screw to ensure that the end effector of the asymmetric five-bar linkage always maintains a convex pentagonal structure and avoids dead points.

[0020] The asymmetric five-bar linkage belongs to the robot's leg mechanism, and its movable links form the legs of the leg mechanism; the leg mechanism enables the robot to move with six degrees of freedom, and the degrees of freedom of each leg of the leg mechanism include two leg degrees of freedom and one wheel degree of freedom at the foot end.

[0021] The leg joints of the leg mechanism are driven by the first joint motor and the second joint motor at the leg joint.

[0022] The first joint motor and the second joint motor are located at the joint support on the bottom plate of the robot body (3), and a coupling is provided at the output shaft to reduce the radial force load on the output shaft of the joint motor.

[0023] In the main body, the robot's base plate is made of 10 mm thick acrylic sheet, the joint supports are to be made by thermomelting deposition 3D printing, and the couplings are made of aluminum parts cut by CNC.

[0024] Neither the first joint motor nor the second joint motor has a speed reducer; both are directly driven by built-in drivers. The first joint motor and the second joint motor receive motor control commands through a communication interface.

[0025] A method for switching between wheel-leg and vehicle modes in a dual-mode deformable wheel-leg robot, using the dual-mode deformable wheel-leg robot described above, is characterized in that: when the wheel-leg robot lowers its auxiliary wheels to make them contact the ground, its chassis is in a four-wheel support mode that can lower the robot's center of gravity, and the robot works in a statically stable four-wheel working condition suitable for driving on flat roads.

[0026] When the wheeled robot retracts its auxiliary wheels and lifts off the ground, the chassis is in a wheeled mode similar to a two-wheeled self-balancing vehicle. The robot operates in a highly mobile, dynamically balanced two-wheeled state that allows it to flexibly overcome obstacles.

[0027] The specific method for switching between static stable four-wheel working condition and dynamic balanced two-wheel working condition is as follows: by rotating the first joint motor and the second joint motor to the required set angle, the first link and the second link are driven respectively to change the leg posture of the leg mechanism.

[0028] When the wheeled robot is working in a dynamic balance dual-wheel mode and needs to jump over obstacles, the auxiliary wheel is lifted by the first joint motor and the second joint motor, and the active wheel is quickly put into force on the ground by the leg mechanism, so that the main body of the robot jumps off the ground. The rotational torque formed by the two active wheels on the leg system keeps the robot stable in the air.

[0029] This invention discloses a bipedal robot system with both wheel-leg and cart modes. By adding retractable auxiliary wheels to the rear of the knee joint, the robot's configuration can autonomously change shape. In wheel-leg mode, the robot exhibits high mobility and agile obstacle-crossing ability. When switching to cart mode on a flat surface, the auxiliary wheels provide ground support, forming a four-wheel structure. This lowers the robot's center of gravity, transitioning it from dynamic equilibrium to a statically stable state, significantly saving energy and enhancing operational stability. This invention features a compact structure and simple control, effectively solving the problem of balancing energy consumption and stability in traditional wheel-leg robots.

[0030] This invention aims to overcome the technical shortcomings of existing bipedal robots, such as high energy consumption and difficulty in balancing stability and mobility, and provides a compact, autonomously deformable dual-mode robot system. Through an innovative knee joint auxiliary wheel design, it achieves intelligent switching between wheeled mode and vehicle mode, thus achieving the comprehensive goals of energy efficiency optimization, enhanced stability, and improved scene adaptability.

[0031] The beneficial effects of the present invention regarding a modally deformable wheeled robot and its wheeled-leg-vehicle mode switching method are:

[0032] 1. The wheeled robot leg configuration proposed in this invention adopts an asymmetric five-bar linkage mechanism, which can improve the leg support performance of the dual-wheeled robot and reduce the joint torque output of the robot; key components are made of acrylic laser cutting and printing, reducing processing costs.

[0033] 2. This invention has strong motion adaptability. By adding two auxiliary wheels to the basic two-wheeled legged robot, it can switch between two-wheeled and four-wheeled modes, thus possessing the advantages of both types of robots and balancing excellent flexibility and strong stability.

[0034] 3. The bipedal robot of this invention has a simple design, small size, and light weight. It has six active degrees of freedom in its whole body, of which each leg has three degrees of freedom, including two leg degrees of freedom and one wheel at the end of the leg. Attached Figure Description

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] Figure 1 is a schematic diagram of the overall structure of the wheel-foot mode according to an example of the present invention;

[0037] Appendix Figure 2 This is a side view of the overall structure of the wheel-foot mode according to an example of the present invention;

[0038] Appendix Figure 3 This is a schematic cross-sectional view of the auxiliary wheel structure in an example of the present invention;

[0039] Appendix Figure 4 This is a schematic diagram of the joint placement in an embodiment of the present invention;

[0040] Appendix Figure 5 This is a schematic diagram of the joint actuator explosion in an example of the present invention;

[0041] Appendix Figure 6 This is a side view of the overall structure of the vehicle in the embodiment of the present invention;

[0042] In the diagram: 1-Second joint motor, 2-Fourth link, 3-Robot body, 4-First joint motor, 5-First link, 6-Auxiliary wheel, 7-Second link, 8-Drive wheel (including wheel motor), 9-Third link. Detailed Implementation

[0043] As shown in the figure, the dual-mode deformable wheeled robot has a main body 3 with a leg mechanism. The leg mechanism includes a chassis with wheel components. The wheel components include an auxiliary wheel 6 located at one end of the chassis and an active wheel 8 located at the other end of the chassis for driving the chassis. The chassis is connected to the main body of the robot via a knee joint mechanism. The knee joint mechanism includes a linkage mechanism connected to the main body of the robot via the leg joint. A joint motor is provided at the leg joint. When the robot moves, the active wheel drives the chassis to move, and the joint torque output by the joint motor drives the five-bar linkage to adjust the chassis posture, thereby changing the contact state between the auxiliary wheel and the ground.

[0044] The drive wheel includes a hub motor structure consisting of a rubber tire and a wheel motor.

[0045] The auxiliary wheel includes a rubber tire; the drive wheel is the front wheel of the chassis.

[0046] The linkage mechanism is used for the retraction and extension of the auxiliary wheels. It is an asymmetric five-bar linkage mechanism that can improve the support performance of the robot's legs and reduce the joint torque output.

[0047] The articulated motor includes a first articulated motor and a second articulated motor. The asymmetric five-bar linkage includes four acrylic links, wherein the second link is a stationary link located at the chassis. All links are manufactured by laser cutting.

[0048] Of the four links, one end of the first link 5 at the robot body is connected to the output end of the first joint motor 4 at the robot body, and the other end is hinged to the auxiliary wheel side of the second link 7 on the chassis. One end of the second link is hinged to the wheel foot motor of the drive wheel.

[0049] Preferably, one end of the third link 9 is hinged to the second link, and this hinge point can slide at the second link. The other end is hinged to one end of the fourth link 2 at the robot body, and the other end of the fourth link is connected to the output end of the second joint motor 1 at the robot body.

[0050] The asymmetric five-bar linkage employs a double-bearing fixing structure at each hinge point, using flanged deep groove ball bearings to fix the upper and lower ends, with washers separating adjacent links in the middle.

[0051] The asymmetric five-bar linkage uses a locking screw to ensure that the end effector of the asymmetric five-bar linkage always maintains a convex pentagonal structure and avoids dead points.

[0052] The asymmetric five-bar linkage belongs to the robot's leg mechanism, and its movable links form the legs of the leg mechanism; the leg mechanism enables the robot to move with six degrees of freedom, and the degrees of freedom of each leg of the leg mechanism include two leg degrees of freedom and one wheel degree of freedom at the foot end.

[0053] The leg joints of the leg mechanism are driven by the first joint motor and the second joint motor at the leg joint.

[0054] The first joint motor and the second joint motor are located at the joint support on the bottom plate of the robot body 3, and a coupling is provided at their output shaft to reduce the radial force load on the output shaft of the joint motor.

[0055] In the main body, the robot's base plate is made of 10 mm thick acrylic sheet, the joint supports are to be made by thermomelting deposition 3D printing, and the couplings are made of aluminum parts cut by CNC.

[0056] Neither the first joint motor nor the second joint motor has a speed reducer; both are directly driven by built-in drivers. The first joint motor and the second joint motor receive motor control commands through a communication interface.

[0057] A method for switching between wheel-leg and vehicle modes in a dual-mode deformable wheel-leg robot, using the dual-mode deformable wheel-leg robot described above, is characterized in that: when the wheel-leg robot lowers its auxiliary wheels to make them contact the ground, its chassis is in a four-wheel support mode that can lower the robot's center of gravity, and the robot works in a statically stable four-wheel working condition suitable for driving on flat roads.

[0058] When the wheeled robot retracts its auxiliary wheels and lifts off the ground, the chassis is in a wheeled mode similar to a two-wheeled self-balancing vehicle. The robot operates in a highly mobile, dynamically balanced two-wheeled state that allows it to flexibly overcome obstacles.

[0059] The specific method for switching between static stable four-wheel working condition and dynamic balanced two-wheel working condition is as follows: by rotating the first joint motor and the second joint motor to the required set angle, the first link and the second link are driven respectively to change the leg posture of the leg mechanism.

[0060] When the wheeled robot is working in a dynamic balance dual-wheel mode and needs to jump over obstacles, the auxiliary wheel is lifted by the first joint motor and the second joint motor, and the active wheel is quickly put into contact with the ground by the leg mechanism, so that the chassis tilts quickly and the robot body jumps off the ground. The rotational torque generated by the two active wheels on the leg system keeps the robot stable in the air.

[0061] In this example, the robot's main body shell is made of 3D printed material, with built-in control circuitry and corresponding supports designed for the joint motors. The joint motors are connected to the robot's base plate via the base. A corresponding coupling was also designed for the output shaft to reduce the radial force on the joint motor output shaft.

Claims

1. A dual-mode deformable wheeled robot, characterized in that: The robot body (3) of the robot is provided with a leg mechanism, which includes a chassis with wheel and foot components. The wheel and foot components include an auxiliary wheel (6) located at one end of the chassis and an active wheel (8) located at the other end of the chassis for driving the chassis to move. The chassis is connected to the robot body via a knee joint mechanism, which includes a linkage mechanism connected to the robot body via a leg joint. A joint motor is provided at the leg joint. When the robot moves, the active wheel drives the chassis to move, and the joint torque output by the joint motor drives the five-bar linkage to adjust the chassis posture, thereby changing the contact state between the auxiliary wheel and the ground.

2. The dual-mode deformable wheeled robot according to claim 1, characterized in that: The drive wheel includes a hub motor structure consisting of a tire and a wheel motor.

3. The dual-mode deformable wheeled robot according to claim 2, characterized in that: The auxiliary wheel includes a rubber tire; the drive wheel is the front wheel of the chassis.

4. The dual-mode deformable wheeled robot according to claim 2, characterized in that: The linkage mechanism is used for the retraction and extension of the auxiliary wheels. It is an asymmetric five-bar linkage mechanism that can improve the support performance of the robot's legs and reduce the joint torque output.

5. The dual-mode deformable wheeled robot according to claim 2, characterized in that: The articulated motor includes a first articulated motor and a second articulated motor. The asymmetric five-bar linkage includes four links, wherein the second link is a stationary link located at the chassis. Of the four links, one end of the first link (5) at the robot body is connected to the output end of the first joint motor (4) at the robot body, and the other end is hinged to the auxiliary wheel side of the second link (7) on the chassis. One end of the second link is hinged to the wheel foot motor of the drive wheel. One end of the third link (9) is hinged to the second link, and the other end is hinged to one end of the fourth link (2) on the robot body. The other end of the fourth link is connected to the output end of the second joint motor (1) on the robot body.

6. The dual-mode deformable wheeled robot according to claim 5, characterized in that: The asymmetric five-bar linkage employs a double-bearing fixing structure at each hinge point, using flanged deep groove ball bearings to fix the upper and lower ends, with washers separating adjacent links in the middle. The asymmetric five-bar linkage is fixed by locking with screws.

7. The dual-mode deformable wheeled robot according to claim 5, characterized in that: The asymmetric five-bar linkage belongs to the robot's leg mechanism, and its movable links form the legs of the leg mechanism; the leg mechanism enables the robot to move with six degrees of freedom, and the degrees of freedom of each leg of the leg mechanism include two leg degrees of freedom and one wheel degree of freedom at the foot end. The leg joints of the leg mechanism are driven by the first joint motor and the second joint motor at the leg joint. The first joint motor and the second joint motor are located at the joint support on the bottom plate of the robot body (3), and a coupling is provided at the output shaft to reduce the radial force load on the output shaft of the joint motor.

8. The dual-mode deformable wheeled robot according to claim 5, characterized in that: Neither the first joint motor nor the second joint motor has a speed reducer; both are directly driven by built-in drivers. The first joint motor and the second joint motor receive motor control commands through a communication interface.

9. A method for switching between wheel-leg and vehicle modes in a dual-mode deformable wheel-legged robot, using the dual-mode deformable wheel-legged robot as described in any one of claims 1-8, characterized in that: When the wheeled robot lowers its auxiliary wheels to make contact with the ground, its chassis is in a four-wheel support mode that lowers the robot's center of gravity. The robot works in a statically stable four-wheel condition suitable for driving on flat roads. When the wheeled robot retracts its auxiliary wheels and lifts off the ground, the chassis is in wheeled mode, and the robot operates in a dynamic balance dual-wheel mode that allows it to flexibly overcome obstacles. The specific method for switching between static stable four-wheel working condition and dynamic balanced two-wheel working condition is as follows: by rotating the first joint motor and the second joint motor to the required set angle, the first link and the second link are driven respectively to change the leg posture of the leg mechanism.

10. The method for switching between wheel-leg and vehicle modes of a dual-mode deformable wheel-legged robot according to claim 9, characterized in that: When the wheeled robot is working in a dynamic balance dual-wheel mode and needs to jump over obstacles, the auxiliary wheel is lifted by the first joint motor and the second joint motor, and the active wheel is quickly put into force on the ground by the leg mechanism, so that the main body of the robot jumps off the ground. The rotational torque formed by the two active wheels on the leg system keeps the robot stable in the air.

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