Biped robot foot structure capable of adapting to complex road surfaces

Abstract

According to the biped robot foot structure capable of adapting to the complex road surface, the whole foot structure is designed through modular decomposition, when a user walks on the wet and slippery flat ground, the foot obtains information of foot sole sensors on the front foot sole and the rear foot sole in real time, and the virtual constraint structure is actively controlled through an electric cylinder; stress of a front longitudinal arch sole joint is reduced, meanwhile, the ground pressure transmission direction of a foot structure is improved, the ground pressure is kept in a friction cone as much as possible, and therefore the robot is prevented from slipping; when the robot walks on an uneven road surface, the electric cylinder actively controls the ground contact angle of the front foot sole, and the spring guide rod of the rear foot sole is assisted, so that active and passive self-adaptive adjustment of the foot of the robot to the ground is realized. The electric cylinder is used as a virtual constraint structure for active control, and the spring telescopic rod structure of the rear sole imitating ligament is combined, so that active and passive self-adaption of the feet of the robot to different complex road surfaces is realized, and the adaptability of the biped robot to the complex road surfaces is improved.

Description

Technical Field

[0001] The invention relates to the technical field of robots, and in particular to a foot structure of a bipedal robot capable of adapting to complex road surfaces. Background Art

[0002] In recent years, with the continuous development of robotics technology, more and more robots have participated in human life and played an important role in all walks of life. Compared with traditional industrial manufacturing robots and wheeled robots, the bipedal walking movement mode makes bipedal robots have higher flexibility and excellent environmental adaptability, especially in the working environment designed for humans, avoiding major changes to the working environment; and compared with multi-legged robots, bipedal robots are smaller in size, consume less energy, and can better perform tasks in some narrow spaces; in addition, bipedal robots are close to humans in terms of shape and movement. The research on the structure and walking of humanoid robots is also of great reference significance for the development of future medical rehabilitation equipment and prosthetic technology.

[0003] In the current research on the walking stability of bipedal robots, great progress has been made in gait planning and motion control. As the only structure in contact with the ground during walking, the foot structure of the bipedal robot is also an important factor affecting the walking stability of the robot. At present, the foot structure of most bipedal robots is relatively simple, usually using a simple flat-bottomed rectangle. This simple structure will restrict the robot's footing method. In a complex walking environment, due to the uncertainty of the road surface, it is easy to become unstable. Therefore, the robot's foot structure will directly affect the robot's walking stability, and its mechanical structure needs to be further optimized.

[0004] The Chinese invention patent with the publication number CN115892283A discloses a humanoid robot foot structure that passively adapts to uneven ground. The invention patent connects the forefoot component and the waist and heel component through a torsion spring and an elastic element, and realizes the passive adaptation of the foot structure to uneven roads by means of the characteristics of the torsion spring and the elastic element. However, the design requirements of the elastic assembly connecting the metatarsal bones and the toes are relatively high. On the one hand, the gear is used as a transmission structure. When it is impacted by the ground, it will cause damage to the gear transmission structure, resulting in plastic deformation, gear breakage and other phenomena, which ultimately affect the adaptability of the foot structure to uneven ground; on the other hand, the arch structure of the design is a two-stage type. When the robot walks on a slippery road, the pressure from the ankle joint will drive the heel bone and the navicular bone to press down the long plantar ligament, causing the pressure direction from the ankle joint to shift, thereby causing the robot foot to slide. This design is not universal for robots walking on complex roads. Summary of the invention

[0005] In order to solve the problem of adaptability of the existing bipedal robot foot structure to complex road environments, the present invention provides a bipedal robot foot structure that is adaptable to complex road environments based on the bionics principle. By imitating the arch structure, the foot structure can realize adaptive stiffness adjustment to the ground conditions; based on the virtual constraint structure driven by the electric cylinder, by controlling the output force and stroke of the electric cylinder, the posture of the sole thin plate is actively adjusted, and the stress condition of the sole-toe joint is improved; through the imitating ligament structure composed of the spring guide rod structure, the impact force of the foot structure when landing can be reduced, and the foot structure can be passively adjusted to the ground. Based on the combination of active and passive adjustment methods and the arch and ligament structure based on the bionics principle, the foot structure can adapt to complex road surfaces such as slippery and uneven, and improve the stability and adaptability of the robot's walking.

[0006] The object of the present invention is achieved through the following technical solutions: a bipedal robot foot structure that can adapt to complex road surfaces, including a front sole thin plate, a rear sole thin plate, a leaf spring connecting the front and rear soles, a front longitudinal arch, a rear longitudinal arch, an arch connecting platform, a virtual constraint structure driven by an electric cylinder, and a spring guide rod structure;

[0007] The front sole thin plate and the rear sole thin plate are connected by a leaf spring; the front longitudinal arch and the rear longitudinal arch are connected by an arch connecting platform; and a flange hole for connecting an ankle joint motor is provided on the top of the arch connecting platform;

[0008] The front longitudinal arch is hinged to the front sole thin plate, and the rear longitudinal arch is hinged to the rear sole thin plate; one end of the virtual constraint structure driven by the electric cylinder is hinged to the front longitudinal arch, and the other end is hinged to the front sole thin plate;

[0009] The spring guide rod structure comprises an upper guide rod part, a lower guide rod part and a compression spring therebetween; the upper guide rod part is hinged to the rear longitudinal arch, and the lower guide rod part is hinged to the rear sole thin plate.

[0010] Furthermore, the virtual constraint structure driven by the electric cylinder has a pin connection hole for connecting the front plantar thin plate and a pin connection hole for connecting the front longitudinal arch, forming a joint in which the front longitudinal arch and the front plantar thin plate are connected by pins, thereby improving the stress condition of the sole-toe joint structure; and driving the electric cylinder to adjust the angle between the front longitudinal arch and the front plantar thin plate to adapt to the undulations of the ground.

[0011] Furthermore, one end of the upper part of the guide rod is a hollow cylindrical structure, and the other end has a pin connection hole for connecting to the rear sole thin plate; one end of the lower part of the guide rod has a pin connection hole connected to the rear sole thin plate, and the other end is inserted into the hollow part of the upper part of the guide rod; the compression spring is sleeved on the connecting part between the upper part of the guide rod and the lower part of the guide rod.

[0012] Furthermore, posture sensors for detecting foot posture data are installed on the front sole thin plate and the rear sole thin plate, and the sensor data is transmitted to the robot control system via wires.

[0013] Furthermore, the anterior longitudinal arch, the posterior longitudinal arch, and the arch connecting platform together constitute a bionic arch structure. During walking, the anterior longitudinal arch and the posterior longitudinal arch change their inclination angles to drive the leaf spring to stretch, thereby dynamically adjusting the stiffness of the foot structure. On slippery roads, the arch structure can lower the center of gravity of the foot structure and stabilize the pressure direction of the ankle joint by adjusting the angle between the arch connecting platform and the anterior longitudinal arch and the posterior longitudinal arch, thereby preventing slipping.

[0014] Furthermore, the rear longitudinal arch, the spring guide rod structure, and the rear plantar thin plate together form a simulated ligament structure, which passively adapts to changes in terrain and improves the flexibility of the foot structure.

[0015] Furthermore, the pin connection holes of the front longitudinal arch, the rear longitudinal arch and the arch connecting platform are all provided with groove structures for fixing the torsion spring. When connected, the cylindrical pin passes through the torsion spring and the pin hole, and cooperates with the groove at the pin hole to fix the torsion spring, thereby realizing the articulation between the arch connecting platform and the front longitudinal arch and the rear longitudinal arch; the torsion spring will adaptively adjust the inclination angle between the front longitudinal arch and the rear longitudinal arch during the walking process of the robot.

[0016] The beneficial effects of the present invention are as follows:

[0017] The optimized design layout of the arch mechanism in the present invention enables the bipedal robot to walk on uneven roads, and can actively adjust the stiffness of the foot structure, thereby improving the walking stability and adaptability of the robot and improving the walking flexibility of the robot.

[0018] On the one hand, the virtual constraint structure driven by the electric cylinder in the present invention can actively adjust the angle between the front longitudinal arch and the front plantar thin plate, so that the robot can actively adapt to the undulations of the ground; on the other hand, during the walking process of the robot, the electric cylinder actively applies a certain support to the front longitudinal arch, which can effectively improve the stress condition of the sole-toe joint, improve the stability of the foot structure, and extend the service life of the foot structure.

[0019] The arch mechanism, virtual constraint structure and simulated ligament structure in the present invention cooperate to actively adjust the direction of pressure from the ankle joint of the robot to keep it within the friction cone, eliminate foot sliding, and enable the robot to walk stably on slippery roads. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 An axonometric diagram of the foot structure of a biped robot in an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the arch structure components of the foot structure of a bipedal robot in an embodiment of the present invention;

[0022] Figure 3Schematic diagram of the spring guide rod structure components of the foot structure of a biped robot in an embodiment of the present invention;

[0023] Figure 4 An axial view of the plantar structure of a bipedal robot according to an embodiment of the present invention;

[0024] Figure 5 This is a front view of the foot structure of a biped robot in an embodiment of the present invention;

[0025] Figure 6 A top view of the foot structure of a bipedal robot according to an embodiment of the present invention;

[0026] Figure 7 4 is a cross-sectional view of the arch platform of the foot structure of a bipedal robot in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical route of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments and drawings. It should be noted that the embodiments described below are only used to explain the content of the present invention, and are not used to limit the present invention.

[0028] like Figure 1 As shown, the present invention provides a bipedal robot foot structure that can adapt to complex road surfaces, including a front plantar thin plate 8, a rear plantar thin plate 4, a leaf spring 11 connecting the front and rear soles, a front longitudinal arch 2, a rear longitudinal arch 3, an arch connecting platform 1, an electric cylinder-driven virtual constraint structure 10, a spring guide rod structure 12, and a posture sensor 28 for obtaining posture information of the front and rear plantar thin plates.

[0029] like Figure 4 As shown, the central axes of the front sole thin plate 8 and the rear sole thin plate 4 are arranged to coincide, and the posture sensor 28 is fixedly installed at the center of the front sole thin plate 8 and the rear sole thin plate 4. The front sole thin plate 8 and the rear sole thin plate 4 are connected to the cylindrical pin and the leaf spring 11 connecting the front and rear soles through symmetrically distributed raised pin holes, and the leaf spring 11 is in a herringbone shape;

[0030] like Figure 3 As shown, the spring guide rod structure 12 includes a guide rod upper part 5, a guide rod lower part 6 and a compression spring 7; the guide rod upper part 5 is hinged to the rear longitudinal arch 3, and the guide rod lower part 6 is hinged to the rear sole thin plate 4. One end of the guide rod upper part 5 is a hollow cylindrical structure, and the other end has a pin connection hole for connecting to the rear sole thin plate; one end of the guide rod lower part 6 has a pin connection hole connected to the rear sole thin plate, and the other end is inserted into the hollow part of the guide rod upper part 5; the compression spring 7 is sleeved on the connecting part of the guide rod upper part 5 and the guide rod lower part 6.

[0031] like Figure 5 and Figure 6As shown, the front plantar thin plate 8 is connected to the electric cylinder driving end of the virtual constraint structure 10 driven by the cylindrical pin and the electric cylinder through the raised pin hole located at the rear end of the central axis; the rear plantar thin plate 4 is connected to the lower part 6 of the guide rod of the cylindrical pin and the spring guide rod structure 12 through the raised pin hole located at the rear end of the central axis.

[0032] The front longitudinal arch 2 is connected to the raised pin hole at the front end of the front plantar thin plate 8 through a cylindrical pin. There is a hollow groove in the middle of the front longitudinal arch 2, and there is a pin hole in the middle of the hollow groove. The moving end of the virtual constraint structure 10 driven by the electric cylinder is connected to the pin hole of the hollow groove through a cylindrical pin; the outer side of the pin hole at the tail of the front longitudinal arch 2 has a groove fixedly matched with the torsion spring 13. The lower front end of the rear longitudinal arch 3 is connected to the raised pin hole at the front end of the rear plantar thin plate 4 through a cylindrical pin, and the rear end is connected to the guide rod upper part 5 of the spring guide rod structure 12 through a cylindrical pin; the outer side of the pin hole at the upper front end of the rear longitudinal arch 3 has a groove fixedly matched with the torsion spring 13; the middle part of the rear longitudinal arch 3 is grooved to reduce weight. Figure 2 and Figure 7 As shown, the top of the arch connection platform 1 has a flange hole for connecting with the ankle joint, and the inner side of the raised pin hole connected with the front longitudinal arch 2 and the rear longitudinal arch 3 has a groove for fixing with the torsion spring 13. This structure needs to be obtained by special processing technology. During assembly, the torsion spring 13 is first installed between the front longitudinal arch 2, the rear longitudinal arch 3 and the arch connection platform 1, and then the cylindrical pin 22 is passed through the pin holes of the arch connection platform 1 and the front longitudinal 2 and rear longitudinal arch 3 to complete the assembly of the arch structure.

[0033] In order to obtain the posture information of the plantar thin plate, it is necessary to install posture sensors 28 on the front plantar thin plate 8 and the rear plantar thin plate 4 respectively. The posture sensor 28 is fixed on the plantar thin plate in the form of a patch, and the posture data of the plantar thin plate is transmitted to the robot's main control host computer for analysis through wired transmission.

[0034] During the robot's walking process, the front longitudinal arch 2 and the rear longitudinal arch 3 will passively and adaptively adjust the angle according to the ground conditions and the pressure of the robot's foot structure under the action of the torsion spring 13, and at the same time drive the leaf spring 11 to expand and contract, thereby realizing the dynamic adjustment of the stiffness of the foot structure. In addition, when encountering a slippery road surface, the arch can be actively driven by the virtual constraint structure 10 driven by the electric cylinder to control the displacement of the electric cylinder 10, and coordinate the leaf spring 11 and the torsion spring 13 to adjust the angle between the front longitudinal arch 2 and the rear longitudinal arch 3 and the arch platform 1, lower the center of the foot structure, make the arch platform as parallel to the ground as possible, and stabilize the direction of the pressure from the ankle joint, keep it in the friction cone as much as possible, so that the robot's pressure on the ground is as perpendicular to the ground as possible to prevent slipping, and actively adapt to the ups and downs of the ground.

[0035] The simulated ligament structure composed of the posterior longitudinal arch 3, the spring guide rod structure 12, and the rear plantar thin plate 4 can reduce the impact force from the ground when the foot structure lands. At the same time, the spring guide rod structure 12 can be retracted and retracted to passively adapt to changes in terrain, thereby improving the flexibility of the rear plantar thin plate and improving the passability of the foot structure in complex terrain.

[0036] In addition to realizing passive adaptation of the structure to complex road surfaces, active adaptation also needs to be realized. Due to the uncertainty of complex road surfaces, passive adaptive adjustment relying solely on mechanical structures cannot completely overcome the disturbance of complex ground surfaces, so an additional active adaptive structural device is required. On the one hand, the virtual constraint 10 structure driven by the electric cylinder actively controls the displacement of the electric cylinder 10 according to the posture information provided by the plantar posture sensor 28 during the robot's walking process, adjusts the ground contact angle of the front plantar thin plate 8 during the leg lifting stage, and adjusts the angle of the front longitudinal arch 2 during the support stage to actively adjust the stiffness of the foot structure; on the other hand, when the front plantar thin plate 8 is in contact with the ground, the virtual constraint structure 10 can actively control the output force of the electric cylinder, thereby applying a supporting force to the front longitudinal arch 2, which can reduce the force and torque of the sole-toe joint, thereby improving the stress condition of the sole-toe joint and reducing the size of this joint.

[0037] The toe joint is an important structure of the human foot. In the human cyclic gait, the toe joint maintains the balance of the supporting foot between the two gait stages from heel off to toe off. Therefore, the introduction of the toe joint plays an important role in improving the mobility and stability of the human robot foot. In the stage of human heel off, due to the flexibility of skin and muscles, the forefoot and toes can be in surface contact with the ground, and the sole of the foot shares part of the force of the toe joint; while the robot's sole structure is difficult to achieve surface contact between the forefoot and toes and the ground in order to maintain rigidity, so the present invention proposes a sole-toe joint structure composed of a front longitudinal arch 2, a virtual constraint structure 10 and a front sole thin plate 8. This structure can achieve surface contact between the robot foot and the ground, reduce the risk of the robot slipping on a slippery road surface, and at the same time, by introducing a virtual constraint structure 10 driven by an electric cylinder at the front longitudinal arch 2, the force of the sole-toe joint is improved, thereby reducing the size of the sole-toe joint while ensuring the structural strength.

[0038] According to the description of the above embodiments, Figure 1 and Figure 6 These are the front view and top view of the robot's foot structure. Through the mutual cooperation of the front longitudinal arch 2, the arch connecting platform 1, the rear longitudinal arch 3, the virtual constraint structure 10, the spring guide rod structure 12, and the plantar leaf spring structure 11, the foot structure can achieve passive and active adaptive adjustments to complex road surfaces, thereby improving the robot's walking ability.

[0039] In short, the above process is only an embodiment of the present invention and cannot be used to limit the scope of application of the present invention. The part naming method adopted in this article is to better illustrate the structural entity and does not exclude the possibility of using other terms. It can be understood that any modification, replacement and other operations made within the design principle and structural design scope of the present invention are within the protection scope of the present invention.

Claims

1. A bipedal robot foot structure that can adapt to complex road surfaces, characterized in that: It comprises a front sole thin plate (8), a rear sole thin plate (4), a leaf spring (11) connecting the front and rear soles, a front longitudinal arch (2), a rear longitudinal arch (3), an arch connecting platform (1), a virtual constraint structure (10) driven by an electric cylinder, and a spring guide rod structure (12); The front sole thin plate (8) and the rear sole thin plate (4) are connected via a leaf spring (11); the front longitudinal arch (2) and the rear longitudinal arch (3) are connected via an arch connecting platform (1); The front longitudinal arch (2) is hinged to the front sole thin plate (8), and the rear longitudinal arch (3) is hinged to the rear sole thin plate (4); one end of the virtual constraint structure (10) driven by the electric cylinder is hinged to the front longitudinal arch (2), and the other end is hinged to the front sole thin plate (8); The spring guide rod structure (12) comprises a guide rod upper part (5), a guide rod lower part (6) and a compression spring (7) therebetween; the guide rod upper part (5) is hinged to the rear longitudinal arch (3), and the guide rod lower part (6) is hinged to the rear sole thin plate (4).

2. The foot structure of a biped robot capable of adapting to complex roads according to claim 1, characterized in that: The virtual constraint structure (10) driven by the electric cylinder has a pin connection hole for connecting the front sole thin plate and a pin connection hole for connecting the front longitudinal arch (2), forming a joint in which the front longitudinal arch (2) and the front sole thin plate (8) are connected by pins, thereby improving the stress condition of the sole-toe joint structure; and driving the electric cylinder to adjust the angle between the front longitudinal arch (2) and the front sole thin plate (8) to adapt to the undulation of the ground.

3. The foot structure of a biped robot capable of adapting to complex roads according to claim 1, characterized in that: One end of the guide rod upper part (5) is a hollow cylindrical structure, and the other end has a pin connection hole for connecting to the rear foot sole thin plate; one end of the guide rod lower part (6) has a pin connection hole connected to the rear foot sole thin plate, and the other end is inserted into the hollow part of the guide rod upper part (5); the compression spring (7) is sleeved on the connection part between the guide rod upper part (5) and the guide rod lower part (6).

4. The foot structure of a biped robot capable of adapting to complex road surfaces according to claim 1, characterized in that: Posture sensors (28) for detecting foot posture data are installed on the front sole thin plate (8) and the rear sole thin plate (4), and the sensor data is transmitted to the robot control system via wires.

5. The foot structure of a biped robot capable of adapting to complex roads according to claim 1, characterized in that: The front longitudinal arch (2), the rear longitudinal arch (3), and the arch connection platform (1) together form a bionic arch structure, and the top of the arch connection platform (1) is provided with a flange hole for connecting an ankle joint motor; during walking, the front longitudinal arch (2) and the rear longitudinal arch (3) change their inclination angles, driving the leaf spring (11) to stretch, thereby dynamically adjusting the stiffness of the foot structure; on slippery roads, the arch structure can adjust the angle between the arch connection platform (1) and the front longitudinal arch (2) and the rear longitudinal arch (3), thereby lowering the center of gravity of the foot structure and stabilizing the direction of ankle joint pressure, so that the pressure is kept within the friction cone as much as possible to prevent slipping.

6. The foot structure of a biped robot capable of adapting to complex roads according to claim 1, characterized in that: The rear longitudinal arch (3), the spring guide rod structure (12) and the rear sole thin plate (4) together form a simulated ligament structure, which passively adapts to changes in terrain and improves the flexibility of the foot structure.

7. The foot structure of a biped robot capable of adapting to complex roads according to claim 1, characterized in that: The pin connection holes of the front longitudinal arch (2), the rear longitudinal arch (3) and the arch connection platform (1) are all provided with groove structures for fixing the torsion spring. When connected, the cylindrical pin (22) passes through the torsion spring and the pin hole, and cooperates with the groove at the pin hole to fix the torsion spring (13), thereby realizing the hinge connection between the arch connection platform (1) and the front longitudinal arch (2) and the rear longitudinal arch (3). The torsion spring will adaptively adjust the inclination angle between the front longitudinal arch (2) and the rear longitudinal arch (3) during the walking process of the robot.

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