A Humanoid Robot Foot Structure for Passively Adapting to Uneven Ground

Abstract

The present invention relates to a humanoid robot foot structure that can passively adapt to uneven ground. This structure is divided into a forefoot component and a heel and ankle component: One end of the forefoot component has three toes, and each toe is connected to the metatarsal bone through a two-degree-of-freedom elastic assembly; the metatarsal bone at the other end is rotatably connected to the navicular bone through a second connecting shaft and two torsion springs; the navicular bone and the calcaneus bone of the heel and ankle component are rotatably connected through a third connecting shaft and two torsion springs, forming the first part of the arch structure; the plantar long ligament is connected to the navicular bone and the calcaneus bone through two elastic elements respectively, forming the second part of the arch structure. This foot structure adopts a three-section design. During the movement of the robot, the foot passively adjusts its posture through several torsion springs and elastic elements, plays a buffering role when subjected to ground forces, realizes self-adaptation to uneven ground, and improves the flexibility, stability and environmental adaptability of the humanoid robot foot.

Description

Technical Field

[0001] The invention relates to the technical field of humanoid robots, and in particular to a foot structure of a humanoid robot capable of passively adapting to uneven ground. Background Art

[0002] As the expected application scenarios of humanoid robots continue to expand, such as cargo handling, personal assistance and care, space exploration, and disaster search and rescue, humanoid robots have become one of the hot topics in contemporary research. With the continuous development of the times, the working environment of humanoid robots will become more complicated, which has higher requirements for the structure of robots. As the only part in contact with the ground, the feet of humanoid robots need to operate in complex environments and have superior environmental adaptability, so their design is particularly important. Analyzing the structural characteristics of human feet, bionics is one of the breakthrough points for improving the walking ability of humanoid robot feet.

[0003] In the prior art, there are two main forms of foot structure design for humanoid robots: one is a flat plate structure, which lacks cushioning and shock absorption, and the flat form forces constraints on its footing method, causing the robot to easily fall in complex environments due to the uncertainty of the walking surface; the other is a two-section structure, usually a two-section structure of toes and soles, or a two-section structure of forefoot and rear soles. The former is not much different from the flat plate structure, and the latter has poor movement flexibility due to the limited degrees of freedom of the forefoot, and it is easy to form point contact or line contact when the foot contacts the uneven ground, which is not conducive to the walking movement of the humanoid robot. Summary of the invention

[0004] The present invention provides a humanoid robot foot structure capable of passively adapting to uneven ground. The toes and metatarsals are connected by a two-degree-of-freedom elastic assembly, and the front end of the foot can adapt to uneven ground, increasing the contact points between the sole and the ground, thereby improving the walking stability of the robot. The various components of the imitation arch structure are connected by a plurality of torsion springs, and the foot can passively expand slightly when subjected to impact force from the ground, thereby playing a role in buffering and shock absorption. Through a three-stage structural design, the robot realizes a bionic behavior mode when a human foot touches the ground during walking, without the need to actively keep the sole parallel to a support surface to ensure stability.

[0005] To achieve the above-mentioned purpose, the technical solution provided by the present invention is as follows: a humanoid robot foot structure that passively adapts to uneven ground, the foot structure comprising a forefoot component and a waist heel component:

[0006] The forefoot component has three toes at one end, each toe is connected to the metatarsal bone through a two-degree-of-freedom elastic assembly; the metatarsal bone is rotatably connected to the navicular bone through a second connecting shaft and two torsion springs;

[0007] The two-degree-of-freedom elastic assembly comprises a central connecting member having four shafts, incomplete gears mounted on both sides of the central connecting member, a torsion spring mounted on the four shafts of the central connecting member, two first connecting shafts, four fixed connecting members and four complete gears;

[0008] Two incomplete gears are installed on each side of the front and rear of the central connecting member, the incomplete gears on different sides are perpendicular to each other, and the incomplete gears on the same side are parallel to each other; each incomplete gear is meshed with a complete gear, and the two complete gears on the same side are installed on the first connecting shaft, and the two ends of the first connecting shaft are rotatably connected to one end of the fixed connecting member, and the other end of the fixed connecting member is installed on the shaft of the central connecting member through a torsion spring; the toes and metatarsals are respectively fixedly connected to a group of fixed connecting members in the two-degree-of-freedom elastic assembly;

[0009] The waist-heel component includes a navicular bone, a calcaneal bone and a long plantar ligament. The navicular bone and the calcaneal bone are rotatably connected via a third connecting shaft and two torsion springs, forming a first part of the arch structure; the two ends of the long plantar ligament are respectively connected to the navicular bone and the calcaneal bone via two elastic elements, forming a second part of the arch structure.

[0010] Furthermore, protrusions are provided on the incomplete gear and the fixed connecting member, and two ends of the torsion spring are in contact with the protrusions of the incomplete gear and the fixed connecting member respectively.

[0011] Furthermore, the radial torsion action of the torsion spring enables the toes to achieve passive adaptive adjustment when subjected to force, and to return to a natural state when not subjected to force.

[0012] Furthermore, the front end of the toe is a hemisphere, and the rear end of the metatarsal bone that contacts the ground is rounded; the toe and metatarsal bone are hollow structures, and a plurality of grooves are cut out of the surface connected to the fixed connecting piece to allow the complete gear in the two-degree-of-freedom elastic assembly to rotate.

[0013] Furthermore, two bosses are provided on the upper end surface of the metatarsal bone, each of which has a hole drilled thereon to form a rotatable connection with the second connecting shaft, and a rotatable connection is formed through the second connecting shaft, two torsion springs and the navicular bone; protrusions are provided on the inner sides of the two bosses and on both sides of the navicular bone to limit the position of the torsion springs.

[0014] Furthermore, the navicular bone and the heel bone are rotatably connected via a third connecting shaft and two torsion springs; a hole is drilled on the front side of the upper end to form a rotatable connection with the third connecting shaft; the front and rear corners of the bottom end in contact with the ground are rounded; protrusions are provided on the inner side of the heel bone and on both sides of the navicular bone to limit the position of the torsion springs; the radial torsion action of the torsion spring causes the navicular bone and the heel bone to slide outward when the arch of the foot is subjected to contact force from the contact surface.

[0015] Furthermore, a boss is provided in the middle part of the navicular bone and the heel bone, and holes are drilled on the bosses, which are connected to the two drilled bosses on the long plantar ligament through two elastic elements, so that the long plantar ligament and the sole of the foot remain parallel in a natural state; the long plantar ligament has a certain toughness, and the elastic element and the long plantar ligament are driven by the navicular bone and the heel bone to jointly bear the impact force of the ground, thereby playing a buffering role during the walking of the robot.

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

[0017] The structural design of the two-degree-of-freedom elastic assembly enables each toe to have two degrees of freedom, which can passively adapt to the surface terrain of uneven ground, increase the contact points between the sole of the foot and the ground, and improve the walking stability of the humanoid robot. The radial torsion action of the limiting torsion spring enables the toe to return to its initial natural state before the next touchdown.

[0018] The waist and heel components share and eliminate the impact force from the ground on the foot when they slide to both sides of the navicular bone and heel bone through torsion springs, elastic elements and long plantar ligaments, simulating the cushioning effect caused by the expansion of the arch of the foot when a person actually walks.

[0019] The entire foot structure has no driving mechanism, which eliminates some calculation links in the robot's walking process and saves the energy required for the driving mechanism to work.

[0020] The foot structure can be divided into three sections according to the contact area with the ground, making the foot structure of the humanoid robot closer to the actual human foot. The flexibility provided by the bionic design improves the robot's ability to adapt to complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0022] Figure 2 is a side view of an embodiment of the present invention;

[0023] Figure 3 is a top view of an embodiment of the present invention;

[0024] Figure 4 is a bottom view of an embodiment of the present invention;

[0025] Figure 5 is a schematic diagram of a toe and a two-degree-of-freedom elastic assembly according to an embodiment of the present invention;

[0026] Figure 6 is a schematic diagram of an assembly of a two-degree-of-freedom elastic assembly part according to an embodiment of the present invention;

[0027] Figure 7 is a schematic diagram of two assemblies of a two-degree-of-freedom elastic assembly according to an embodiment of the present invention;

[0028] Figure 8 It is a schematic structural diagram of a waist and heel component according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0031] The human foot can be divided into three parts: the heel, waist and forefoot. The root is responsible for directly bearing most of the body weight; the waist is responsible for connecting the forefoot and the heel, and transferring part of the body weight to the forefoot; the forefoot has the functions of bearing weight, adapting to the ground and balancing the body.

[0032] The present invention provides a humanoid robot foot structure that can passively adapt to uneven ground from a bionic perspective and with reference to the human foot structure, including:

[0033] The forefoot component has three toes 1 at one end, each toe 1 is connected to a metatarsal bone 3 via a two-degree-of-freedom elastic assembly 2; the metatarsal bone 3 is rotatably connected to the navicular bone 502 via a second connecting shaft 401 and two torsion springs 402.

[0034] The waist and heel part, the waist and heel part, the navicular bone 502 and the heel bone 501 are rotatably connected through a third connecting shaft 503 and two torsion springs 504, forming the first part of the arch structure; the long plantar ligament 505 is respectively connected to the navicular bone 502 and the heel bone 501 through two elastic elements 506, forming the second part of the arch structure.

[0035] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown in FIG. 1 , a humanoid robot foot structure that passively adapts to uneven ground is provided, in which three toes 1 are connected to the same metatarsal bone 3 through three two-degree-of-freedom elastic assemblies 2. Figure 5 , Figure 6 and Figure 7As shown, the two-degree-of-freedom elastic assembly 2 includes a central connecting member 201 , four incomplete gears 202 , four torsion springs 203 , two first connecting shafts 204 , four fixed connecting members 205 and four complete gears 206 .

[0036] The two-degree-of-freedom elastic assembly 2 includes a central connecting member 201 having four shafts, incomplete gears 202 mounted on both sides of the central connecting member 201, torsion springs 203 mounted on the four shafts of the central connecting member 201, two first connecting shafts 207, four fixed connecting members 205 and four complete gears 206. Two incomplete gears 202 are mounted on each side of the central connecting member 201, and the incomplete gears 202 on different sides are perpendicular to each other, and the incomplete gears 202 on the same side are parallel to each other. Each incomplete gear 202 is meshed with a complete gear 206, and the two complete gears 206 on the same side are mounted on the first connecting shaft 207, and the two ends of the first connecting shaft 207 are rotatably connected to one end of the fixed connecting member 205, and the other end of the fixed connecting member 205 is mounted on the shaft of the central connecting member 201 through the torsion spring 203. The toes 1 and the metatarsal bones 3 are respectively fixedly connected to a group of fixed connecting members 205 in the two-degree-of-freedom elastic assembly 2. The incomplete gear 202 and the fixed connecting member 205 are provided with protrusions, and the two ends of the torsion spring 203 are in contact with the protrusions of the incomplete gear 202 and the fixed connecting member 205. The toe 1 and the metatarsal 3 are respectively fixedly connected to a group of fixed connecting members 205 in the two-degree-of-freedom elastic assembly 2. The front end of the toe 1 is a hemisphere, and the rear end of the metatarsal 3 that contacts the ground is a rounded corner. The toe 1 and the metatarsal 3 are hollow structures, and a plurality of grooves are cut out of the surface connected to the fixed connecting member 205 to allow the complete gear 206 in the two-degree-of-freedom elastic assembly 2 to rotate. Due to the characteristics of the two-degree-of-freedom elastic assembly 2, the toe 1 can passively adapt to the uneven ground, increase the contact points between the sole and the ground, and improve the stability of the foot. Two bosses are provided on the upper end surface of the metatarsal 3, each of which is drilled with a hole, and is rotatably connected to the second connecting shaft 401, and is rotatably connected through the second connecting shaft 401, two torsion springs 402 and the navicular bone 502. The inner sides of the two bosses and the two sides of the navicular bone 502 are provided with protrusions for limiting the position of the torsion spring 402. The structural characteristics of the two-degree-of-freedom elastic element 2 enable each toe 1 to have two degrees of freedom, and when touching the ground during walking, it can adapt to uneven ground, and when leaving the ground, it automatically returns to the initial state due to the radial torsion of the torsion spring 203.

[0037] like Figure 8As shown, the metatarsal bone 3 is rotatably connected to the navicular bone 502 through the torsion spring assembly 4, and the torsion spring assembly 4 allows the waist and heel component to rotate relative to the forefoot component around the second connection axis 401, reflecting the flexibility of the foot structure. In order to support the entire body weight, the bottom of the foot has several arches. The waist and heel component in the embodiment has two arch structures, one is the navicular bone 502 and the heel bone 501, and the other is the long plantar ligament 505. The navicular bone 502 and the heel bone 501 are rotatably connected through the third connecting shaft and two torsion springs 504. The heel bone 501 is designed to be in the shape of "7" when viewed from the side. The upper front end is drilled with a hole and is rotatably connected to the third connecting shaft 503. The inner side of the heel bone 501 and the two sides of the navicular bone 502 are provided with protrusions for limiting the position of the torsion spring 504. The long plantar ligament 505 is connected to the drilled bosses on the navicular bone 502 and the heel bone 501 through an elastic element 506, respectively, so that the long plantar ligament 505 and the sole of the foot are kept parallel in a natural state. When the sole of the foot is subjected to contact force from the ground, the heel bone 501 and the navicular bone 502 slide outward, and at the same time, the navicular bone 502 and the metatarsal bone 3 rotate relatively around the torsion spring assembly 4. The long plantar ligament 505 and the elastic element 506 jointly share the ground impact force, and play a buffering role in the process of the robot contacting the ground.

[0038] From the perspective of the robot's movement during the single-leg walking, the human body trunk moves forward, which can be seen as the supporting leg moving backward relative to the human body trunk. The foot at the end of the supporting leg is in the state of maximum contact area with the ground. As the supporting leg tilts, the heel, that is, the calcaneus 501, is lifted, and the navicular bone 502 drives the calcaneus 501 to rotate relative to the metatarsal 3 under the action of the torsion spring assembly 4. Due to the characteristics of the two-degree-of-freedom elastic assembly 2, the metatarsal 3 rotates relative to the toe 1. During the lifting process of the entire foot, the foot is divided into three sections, namely the toe section, the metatarsal section, and the waist and heel section. Three parts leave the ground in turn. After leaving the ground, the supporting leg is converted into a swinging leg, and the various parts of the foot are restored to a natural state under the radial torsion of a number of torsion springs. When the swinging leg is converted into a supporting leg again, the calcaneus 501 touches the ground first. At this time, the toe 1, the metatarsal 3 and the navicular bone 502 are in a natural state before touching the ground. On a flat ground, the toes 1 and metatarsals 3 rotate with the foot with the contact point between the heel bone 501 and the ground as the rotation center and touch the ground at the same time. At this time, under the action of the ground contact force, the heel bone 501 and the navicular bone 502 slide in the front-back direction. During the sliding process of the navicular bone 502, the forefoot component is pushed to move, and the torsion spring 504 is driven by the heel bone 501 to bear force, and the elastic element 506 and the long plantar ligament 505 are pulled to buffer the impact force. On an uneven ground, the toes 1 and metatarsals 3 may not touch the ground at the same time according to the actual terrain of the ground. Due to the two degrees of freedom and elastic characteristics of the two-degree-of-freedom elastic assembly 2, the toes 1 passively adjust their posture to adapt to the ground, increase the contact points between the foot and the ground, and improve the stability of the foot; in addition, as on a flat ground, the torsion spring 504, the elastic element 506 and the long plantar ligament 505 play a buffering role in the process of the foot contacting the ground.

[0039] According to the description of the above embodiments, the three-section foot structure of the robot passively and adaptively adjusts the contact with the uneven ground, and bears the impact force from the ground through a number of torsion springs and elastic elements, which plays a buffering role in the robot's walking process, improves the stability and flexibility of the robot's movement, and significantly enhances the walking ability of the humanoid robot, which is of great significance for conducting experiments on the robot.

[0040] 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 humanoid robot foot structure that passively adapts to uneven ground, characterized in that, the foot structure includes a forefoot component and a heel and waist component: One end of the forefoot component has three toes (1), and each toe (1) is connected to the metatarsal bone (3) through a two-degree-of-freedom elastic combination component (2); the metatarsal bone (3) forms a rotatable connection with the navicular bone (502) through a second connecting shaft (401) and two torsion springs (402); The two-degree-of-freedom elastic combination component (2) includes a central connecting component (201) with four shaft rods, incomplete gears (202) installed on the front and back sides of the central connecting component (201), torsion springs (203) installed on the four shaft rods of the central connecting component (201), as well as two first connecting shafts (204), four fixed connecting components (205) and four complete gears (206); Two incomplete gears (202) are installed on each side of the front and back of the central connecting component (201). The incomplete gears (202) on different sides are perpendicular to each other, and the incomplete gears (202) on the same side are parallel to each other; each incomplete gear (202) meshes with a complete gear (206), and the two complete gears (206) on the same side are installed on the first connecting shaft (204), and both ends of the first connecting shaft (204) are rotatably connected to one end of the fixed connecting component (205). The other end of the fixed connecting component (205) is installed on the shaft rod of the central connecting component (201) through a torsion spring (203); the toe (1) and the metatarsal bone (3) are respectively fixedly connected to a group of fixed connecting components (205) in the two-degree-of-freedom elastic combination component (2); The heel and waist component includes a navicular bone (502), a calcaneus (501) and a plantar long ligament (505). The navicular bone (502) and the calcaneus (501) form a rotatable connection through a third connecting shaft (503) and two torsion springs (504), constituting the first part of the arch structure; both ends of the plantar long ligament (505) are respectively connected to the navicular bone (502) and the calcaneus (501) through two elastic elements (506), constituting the second part of the arch structure.

2. A humanoid robot foot structure that passively adapts to uneven ground according to claim 1, characterized in that, The incomplete gear (202) and the fixed connecting component (205) are provided with protrusions, and both ends of the torsion spring (203) are in contact with the protrusions of the incomplete gear (202) and the fixed connecting component (205) respectively.

3. A humanoid robot foot structure that passively adapts to uneven ground according to claim 1, characterized in that, The radial torsion of the torsion spring (203) enables the toe (1) to achieve passive adaptive adjustment when stressed and return to its natural state when not stressed.

4. A humanoid robot foot structure that passively adapts to uneven ground according to claim 1, characterized in that, The front end of the toe (1) is a hemisphere, and the rear end of the metatarsal bone (3) in contact with the ground is a rounded corner; the toe (1) and the metatarsal bone (3) are hollow structures, and several grooves are cut out on the surface connected to the fixed connecting component (205) to allow the complete gear (206) in the two-degree-of-freedom elastic combination component (2) to rotate.

5. The humanoid robot foot structure for passively adapting to uneven ground according to claim 1, wherein, two convex platforms are provided on the upper end surface of the metatarsal bone (3), and holes are drilled therein respectively to form a rotatable connection with the second connecting shaft (401), and a rotatable connection is formed through the second connecting shaft (401), two torsion springs (402) and the navicular bone (502); protrusions are provided on the inner sides of the two convex platforms and on both sides of the navicular bone (502) to limit the positions of the torsion springs (402).

6. The humanoid robot foot structure for passively adapting to uneven ground according to claim 1, wherein, the navicular bone (502) and the calcaneus bone (501) form a rotatable connection through the third connecting shaft and two torsion springs (504), and a hole is drilled in the front side of the upper end to form a rotatable connection with the third connecting shaft (503), the front and rear of the bottom end in contact with the ground are rounded, and protrusions are provided on the inner side of the calcaneus bone (501) and on both sides of the navicular bone (502) to limit the positions of the torsion springs (504); the radial torsional action of the torsion springs (504) causes the navicular bone (502) and the calcaneus bone (501) to slide outwards when the arch of the foot receives the contact force of the contact surface.

7. The humanoid robot foot structure for passively adapting to uneven ground according to claim 1, wherein, convex platforms are provided in the middle of the navicular bone (502) and the calcaneus bone (501), and holes are drilled therein, and they are connected to the two drilled convex platforms on the plantar long ligament (505) through two elastic elements (506) to keep the plantar long ligament (505) parallel to the sole in the natural state; the plantar long ligament (505) has a certain toughness, and the elastic elements (506) and the plantar long ligament (505) are driven by the navicular bone (502) and the calcaneus bone (501) to jointly bear the ground impact force, playing a buffering role during the walking process of the robot.

Images