Four-wheeled robot, motion method and control system

Abstract

This application belongs to the field of mobile robots, specifically a four-wheeled legged robot, its motion method, and control system. The robot includes a body and lower limb structures located on both sides of the body, with the lower limb structures connecting to the body to form a hip joint. The lower limb structures include a drive assembly, a thigh, a lower leg, and foot drive wheels. The drive assembly is connected to one end of the thigh and the hip joint, respectively. The other end of the thigh connects to one end of the lower leg to form a knee joint, and the other end of the lower leg is connected to the foot drive wheel. A sprocket assembly is installed at the knee joint, and the sprocket assembly is connected to the drive assembly and the foot drive wheel via a chain transmission structure. A ratchet is coaxially mounted on the sprocket assembly. This application enables seamless coordination and synchronization of wheeled movement and legged stepping motion, enhancing the robot's ability to traverse complex terrain.

Description

Technical Field

[0001] This application belongs to the field of mobile robot technology, and more specifically, relates to a four-wheeled legged robot, a motion method, and a control system. Background Technology

[0002] Compared to indoor environments, outdoor environments present a variety of complex challenges, including rugged terrain, ravines, and slippery surfaces, posing a significant obstacle to the research and application of mobile robots. For applications such as emergency rescue and wilderness exploration, the terrain mobility and environmental adaptability of mobile robots in outdoor environments are of paramount importance.

[0003] For mobile robots exploring the wilderness, there are currently wheeled robots, tracked robots, and legged robots. Wheeled robots are flexible and lightweight, but their obstacle-crossing ability is insufficient; tracked robots have good terrain adaptability, but they are slow and inefficient; legged robots have a stronger ability to move autonomously in complex terrains, but they are difficult to control and consume more energy.

[0004] Existing technologies include designs for wheel-legged hybrid robots, but these robots still suffer from numerous design flaws. For example, they can only achieve wheeled or legged movement through structural switching, but lack the ability to perform both simultaneously. Furthermore, the motion of existing wheel-legged hybrid robots is limited by their structural design and control logic, making it difficult to cope with complex and varied terrain and to achieve rapid switching between multiple motion modes. Therefore, there is an urgent need for a wheel-legged robot with excellent adaptability to complex environments and strong mobility. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a four-wheeled legged robot, a motion method and a control system, which aims to solve the problem that the existing wheeled legged composite robots have a single motion mode, making it difficult to cope with complex terrain conditions.

[0006] To achieve the above objectives, in a first aspect, this application provides a four-wheeled legged robot, comprising: a body and lower limb structures disposed on the front and rear ends of the body, wherein the connection between the lower limb structures and the body forms a hip joint; the lower limb structures include a drive assembly, a thigh, a lower leg, and foot drive wheels; the drive assembly is connected to one end of the thigh and the hip joint respectively, the other end of the thigh is connected to one end of the lower leg to form a knee joint, and the other end of the lower leg is connected to the foot drive wheels; a sprocket assembly is installed at the knee joint, the sprocket assembly is connected to the drive assembly and the foot drive wheels respectively through a chain transmission structure, and a ratchet is coaxially provided on the sprocket assembly.

[0007] Furthermore, the outer diameter of the ratchet is larger than the outer diameter of the sprocket assembly, and the ratchet teeth on the periphery of the ratchet face in the opposite direction to its rotation direction; the drive assembly can drive the thigh to rotate around the hip joint, and can also drive the lower leg to rotate around the knee joint relative to the thigh, so that the corresponding foot drive wheel and / or ratchet touches the ground, or so that the corresponding foot drive wheel and / or ratchet leaves the ground, and can also drive the corresponding sprocket assembly to rotate, thereby driving the corresponding ratchet and foot drive wheel to rotate in the same direction.

[0008] Furthermore, the drive assembly includes a hip joint motor, a knee joint motor, and a drive wheel motor. The chain transmission structure includes a first transmission chain, a second transmission chain, and a third transmission chain, wherein: the hip joint motor is fixedly mounted at the hip joint, and its output shaft is fixedly connected to the knee joint motor; the knee joint motor is mounted on the outer side of one end of the thigh and is used to drive the thigh to rotate around the hip joint; a first sprocket is provided on the lower leg, and the output shaft of the knee joint motor is connected to the first sprocket through the first transmission chain to drive the lower leg to rotate around the knee joint; the drive wheel motor is mounted on the outer side of the thigh and is opposite to the knee joint motor, and the output shaft of the drive wheel motor is connected to the sprocket assembly through the second transmission chain; a second sprocket is coaxially fixed on the foot drive wheel, and the sprocket assembly is connected to the second sprocket through the third transmission chain. The drive wheel motor can drive the sprocket assembly to rotate, thereby driving the second sprocket to drive the foot drive wheel to rotate.

[0009] Furthermore, the sprocket assembly includes two coaxially fixed third sprockets, one of which is connected to the drive wheel motor via a second transmission chain, and the other third sprocket is connected to the second sprocket via a third transmission chain.

[0010] Furthermore, the fuselage includes a first fuselage and a second fuselage, which are connected by a hinge to form a waist joint; the first fuselage is provided with a stop structure, which is used to limit the rotation angle of the second fuselage around the waist joint.

[0011] Furthermore, the connecting ends of the first body and the second body are both V-shaped, and the V-shaped tips of the two overlap each other. The stop structure is a V-shaped protrusion provided at the V-shaped tip of the first body. When the second body rotates, the two sides of its V-shaped end can abut against the two sides of the V-shaped protrusion.

[0012] Secondly, this application provides a method for locomotion of the four-wheeled legged robot as described above, including:

[0013] Flat ground walking mode: Control all lower limb structures to lock joint angles as rigid support rods, and make the foot drive wheels rotate in contact with the ground to achieve upright walking; or, control the knee joint to bend, and make all foot drive wheels and ratchet rotate in contact with the ground simultaneously to achieve crawling.

[0014] Obstacle crossing mode: When a low obstacle with a height lower than the upright height of the quadruped robot is detected, the quadruped robot assumes a prone posture. If the width of the low obstacle is not greater than the length of the lower leg, the following steps are performed:

[0015] S1 controls the foot drive wheel that is close to the obstacle to lift off the ground and causes the corresponding ratchet to rotate while still on the ground, driving the robot forward until the foot drive wheel passes the obstacle;

[0016] S2 controls the foot drive wheel that has crossed the obstacle to land and rotate, and causes the corresponding ratchet to leave the ground, so that the obstacle is passively crossed under the drive of the foot drive wheel;

[0017] S3 Repeat steps S1 to S2 until the quadruped robot has completely crossed the obstacle;

[0018] If the width of the low obstacle is greater than the length of the lower leg, then the following steps are performed:

[0019] C1 causes one of the foreleg structures closest to the low obstacle to rotate around its hip joint to lift it off the ground; at the same time, it causes the lower leg of one of the hindleg structures furthest from the low obstacle to rotate, causing its foot drive wheel to move forward to the lower part of the body, and together with another rear foot drive wheel and the ratchet of the unlifted foreleg structure, they form a triangular support area, and the center of gravity of the four-wheeled robot is located within the triangular support area.

[0020] C2 extends the raised foreleg structure to its maximum extent so that it rotates around the corresponding hip joint until the foot drive wheel on it steps onto the flat ground opposite the low obstacle;

[0021] C3 repeats steps C1-C2, sequentially moving the remaining lower limb structures across the low obstacle by shifting the center of gravity;

[0022] When a high obstacle higher than the upright height of the quadruped robot is detected, the following steps are performed:

[0023] P1 controls a pair of lower limb structures at the front end to rotate around their corresponding hip joints, thereby raising the corresponding foot drive wheels and placing them sequentially on the high obstacle;

[0024] P2 controls all foot drive wheels to rotate, driving the four-wheeled legged robot forward as a whole, so that the rear lower limb structure can approach high obstacles;

[0025] Following the method in step P1, P3 sequentially attaches the foot drive wheels of the rear pair of lower limb structures onto the high obstacle to overcome it.

[0026] Furthermore, it also includes a posture recovery mode: when the four-wheeled robot is detected to be tilting to the side, the lower limb structure on the side closer to the ground is controlled to retract, and the robot is flipped to the side away from the ground by the weight of the lower limb structure on the side away from the ground until the body returns to the crawling posture; if the weight is insufficient to achieve the flip, the lower limb structure on the side away from the ground is controlled to perform a retraction and extension action, and the generated inertial torque breaks the balance and assists the robot to complete the flip.

[0027] When the four-wheeled robot detects that its back has touched the ground, it controls all lower limb structures to retract into a folded state, and then makes each thigh rotate around the corresponding hip joint to support the body away from the ground, so that the original back becomes the abdomen.

[0028] Thirdly, this application provides a control system for implementing the aforementioned motion method, including a sensor assembly, a motion control unit, and a central processing unit, wherein: the sensor assembly is deployed on the body and lower limb structure, and is used to detect obstacle information around the robot, posture information of the body, and contact information between the foot drive wheels and ratchet and the ground, and transmits all detection information to the central processing unit; the central processing unit is used to send control commands to the motion control unit based on the detection information; the motion control unit is used to execute corresponding actions based on the control commands to execute a flat ground movement mode or an obstacle crossing mode.

[0029] Furthermore, the sensor assembly includes:

[0030] Inertial measurement unit, used to detect fuselage attitude in real time;

[0031] Motor encoders are used to detect the angles of the hip and knee joints in real time, and also to detect the wheel speeds of the foot drive wheel and ratchet.

[0032] A distance sensor, mounted on the robot body, is used to detect obstacle information around the four-wheeled robot;

[0033] A current detection unit is installed on the foot drive wheel and ratchet to detect the current and determine the contact information between the corresponding foot drive wheel and ratchet and the ground.

[0034] It is understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0035] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art:

[0036] (1) The highly integrated four-wheeled and legged composite robot provided in this application achieves seamless coordination and synchronization of wheeled movement and legged stepping movement through the optimization of the lower limb structure and the use of a single drive system. Specifically, based on wheeled movement, the foot drive wheel always serves as the core drive unit, providing continuous and efficient forward power in any posture (upright or crawling). The leg movement is assisted, and the movement of its knee and hip joints is no longer just about lifting the leg and taking a step, but is used to adjust the height of the robot body in real time, cross obstacles, and control the contact state between the ratchet and the ground. When any foot drive wheel leaves the ground to perform a stepping or other action, the power can still be transmitted to the corresponding ratchet on the ground through chain transmission, ensuring that the driving force of the robot is not interrupted when performing leg movements, and achieving a good integration of movement modes.

[0037] (2) The four-wheeled robot of this application ensures that the direction of travel is the same as the direction of rotation of the drive through the chain transmission. Without increasing the number of motors, the robot’s terrain passability is enhanced. The robot can pass through flat and hard roads by relying solely on the foot drive wheels, and can pass through complex terrains such as slippery roads with the assistance of ratchet. The combined motion of the two can increase friction and power, and complete climbing movements with large slopes or great heights.

[0038] (3) All three motors of the single lower limb structure of this application are concentrated in the hip joint area on the thigh, and the rotation of the lower leg and foot drive wheel is controlled by chain transmission. This design reduces the rotational inertia of the leg and improves the leg's movement ability. With chain transmission, the robot can move in harsh environments, such as the robot can pass through waters where the water depth is lower than the position of the leg motor.

[0039] (4) The movement method of this application includes a flat ground movement mode, multiple obstacle crossing modes and a posture recovery mode. By integrating the high efficiency of wheeled movement with the high adaptability of leg movement, and through ingenious mechanical structure and intelligent control strategy, it realizes efficient, stable and self-recovering movement in various complex environments. For example, on flat ground, this application can "walk upright" or "crawl" stably at high speed and low power consumption like a wheeled robot. When encountering obstacles, it can switch to leg gait to achieve true wheel-leg fusion, rather than simple function superposition. It adopts the sequence of lifting the wheel - using ratchet to propel - lowering the wheel, which is simple and efficient. It adopts the method of using the lower leg to flip to build a triangular stable support, which fundamentally solves the stability problem when crossing wide ditches. It adopts the method of front wheel connection - overall traction - rear wheel connection to realize the high obstacle climbing function.

[0040] (5) The control system of this application deeply couples the mechanical structure and motion strategy of the robot. Through multi-source perception fusion and situational adaptive decision-making, it realizes the robot’s efficient and stable autonomous movement in complex terrain and its powerful self-attitude transformation and recovery capabilities, breaking through the limitations of traditional robot control systems in terms of control efficiency and scene adaptability.

[0041] (6) The control system of this application deeply integrates information such as inertial measurement unit (attitude), distance sensor (environmental obstacle), motor encoder (joint angle / wheel speed) and current detection unit (ground contact force) to accurately determine the contact state and force of the legs and feet with the ground respectively. The current detection unit is used to determine whether the foot drive wheel and ratchet are reliably in contact with the ground. This is the core of realizing stable support switching (such as accurately constructing a triangular support area in obstacle crossing mode) and anti-slip control, ensuring the reliability of action execution. The central processing unit makes real-time judgments and selects modes based on sensor information (such as obstacle height, width, and self-attitude). It can automatically distinguish different scenarios such as flat ground, low obstacles (and further distinguish between wide and narrow), and high obstacles, and trigger corresponding optimized motion modes (flat ground, obstacle crossing, attitude recovery). The motion control unit executes precise coordinated control of each drive motor based on the received task instructions. This hierarchical distributed architecture ensures the stable and coordinated execution of original actions such as reverse flipping of the robot's lower legs, center of gravity transfer, and ratchet / drive wheel switching. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the four-wheeled legged robot structure provided in Embodiment 1 of this application;

[0043] Figure 2 This is a schematic diagram of the lower limb structure provided in Embodiment 1 of this application;

[0044] Figure 3 This is a schematic diagram of the crawling state of the four-wheeled legged robot provided in Embodiment 1 of this application;

[0045] Figure 4 This is a schematic diagram of the steering state of the four-wheeled legged robot provided in Embodiment 1 of this application;

[0046] Figure 5 These are schematic diagrams of four leg states of the four-wheeled legged robot provided in Embodiment 1 of this application;

[0047] Figure 6 This is a schematic diagram of the mixed motion state of the ratchet and foot drive wheel of the four-wheeled legged robot provided in Embodiment 1 of this application;

[0048] Figure 7 This is a schematic diagram of the motion state of a four-wheeled legged robot crossing a low obstacle, provided in Embodiment 2 of this application;

[0049] Figure 8 This is a schematic diagram of the motion state of one front leg of the four-wheeled robot provided in Embodiment 2 of this application crossing a low obstacle;

[0050] Figure 9 This is a top view of the center of gravity position of one of the front legs of the four-wheeled robot provided in Embodiment 2 of this application when it crosses a low obstacle;

[0051] Figure 10 This is a schematic diagram of the movement state of the front legs of the four-wheeled legged robot when climbing high obstacles, as provided in Embodiment 2 of this application;

[0052] Figure 11 This is a schematic diagram of the movement of the hind legs of the four-wheeled leg robot after its front legs have climbed over a high obstacle, as provided in Embodiment 2 of this application;

[0053] Figure 12 This is a schematic diagram of the motion state of the hind legs of the four-wheeled robot provided in Embodiment 2 of this application when climbing a high obstacle;

[0054] Figure 13 This is a schematic diagram of the lateral tilting and righting process of the four-wheeled legged robot provided in Embodiment 2 of this application;

[0055] Figure 14 This is a schematic diagram of the process of a four-wheeled legged robot returning to center after landing on its back, as provided in Embodiment 2 of this application.

[0056] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0057] 1-First fuselage, 2-Second fuselage, 3-Lumbar joint, 4-Hip joint, 5-Hip joint motor, 6-Knee joint motor, 7-Drive wheel motor, 8-Thigh, 9-Lower leg, 10-Foot drive wheel, 101-Second sprocket, 11-Chain drive structure, 12-Ratchet, 13-Sprocket assembly, 131-Third sprocket, 14-Stop structure. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0059] In this article, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this article indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0060] The terms "first" and "second," etc., used in the specification and claims herein are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0061] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0062] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0063] The embodiments of this application are described below with reference to the accompanying drawings.

[0064] Example 1

[0065] This embodiment provides a four-wheeled robot (hereinafter referred to as the robot), such as Figures 1-3 As shown, the robot includes: a body and four lower limb structures (i.e., legs) located on the front and rear ends of the body. The lower limb structures are connected to the body by hinges, and the connection between the two forms a hip joint 4.

[0066] The aforementioned lower limb structure includes a drive assembly, a thigh 8, a lower leg 9, and a foot drive wheel 10. The drive assembly is connected to one end of the thigh 8 and the hip joint 4, respectively. The other end of the thigh 8 is connected to one end of the lower leg 9 to form a knee joint. The other end of the lower leg 9 is connected to the foot drive wheel 10. A sprocket assembly 13 is installed at the knee joint. The sprocket assembly 13 is actually installed at the connection between the lower leg 9 and the thigh 8 through bearings and is located on the outside of the robot body. The sprocket assembly 13 is connected to the drive assembly and the foot drive wheel 10 through a chain transmission structure 11. A ratchet 12 is coaxially fixed on the outside of the sprocket assembly 13. The outer diameter of the ratchet 12 is larger than the outer diameter of the sprocket assembly 13 so that when the ratchet 12 is in contact with the ground, the sprocket assembly 13 is not in contact with the ground, thus avoiding interruption of the driving force.

[0067] The aforementioned drive assembly can drive the thigh 8 to rotate around the hip joint 4, and can also drive the lower leg 9 to rotate around the knee joint relative to the thigh 8, so that the corresponding foot drive wheel 10 and ratchet 12 are on the ground at the same time, or the corresponding foot drive wheel 10 or ratchet 12 are on the ground separately, or the corresponding foot drive wheel 10 and ratchet 12 are off the ground at the same time, or the corresponding foot drive wheel 10 or ratchet 12 are off the ground separately. At the same time, it can also drive the sprocket assembly 13 to rotate, thereby driving the ratchet 12 and the foot drive wheel 10 to rotate in the same direction.

[0068] Specifically, the aforementioned body includes a first body 1 and a second body 2. The first body 1 and the second body 2 are roughly the same shape and are connected by a hinge to form a waist joint 3. This hinge allows the front section 1 of the body to rotate around the z-axis, thereby enabling the robot to turn while moving forward. No motor is installed at the waist joint 3; the rotation of the hinge is driven solely by the differential speed between the four drive wheels, thus completing the robot's turning.

[0069] More specifically, such as Figure 4 The diagram shows the turning state of a four-wheeled robot. In Example 1, the robot has hinges installed on its body for rotation, and its turning angle θ reaches 60°. When the drive wheel is directly below the hip joint, the minimum turning radius is [missing information - likely a percentage] of the body length. This provides the robot with excellent turning ability, with a turning radius of:

[0070]

[0071] The rotational speed of the drive wheel inside the turning radius is:

[0072]

[0073] The rotational speed of the outer drive wheel is:

[0074]

[0075] In other preferred embodiments, the robot's turning ability can be enhanced by installing a rotary motor at the waist joint 3 to achieve active rotation of the robot body, and the robot can also complete turning actions when one leg is suspended in the air.

[0076] The aforementioned first fuselage 1 is provided with a stop structure 14, which is used to restrict the second fuselage 2 from rotating around the waist joint 3 within a certain angle range. In this embodiment, based on the lower limb structure and the length of the two fuselage sections, the angle range of the second fuselage or the first fuselage rotating around the waist joint 3 in one direction is designed to be 0~60°.

[0077] In this embodiment, the ratchet teeth on the periphery of the ratchet 12 are oriented in the opposite direction to the rotation direction of the ratchet 12, so that the ratchet 12 has sufficient friction when it contacts the ground, avoids slipping, and achieves stable movement.

[0078] In this embodiment, the aforementioned drive components include a hip joint motor 5, a knee joint motor 6, and a drive wheel motor 7, enabling each leg to have three degrees of freedom and the entire robot to have at least 12 degrees of freedom. The aforementioned chain transmission structure 11 includes a first transmission chain, a second transmission chain (not shown in the figure), and a third transmission chain (not shown in the figure), wherein: the hip joint motor 5 is fixedly mounted at the hip joint 4, and its output shaft is fixedly connected to the housing of the knee joint motor 6; the knee joint motor 6 is fixedly mounted on the outer side of one end of the thigh 8, used to drive the thigh 8 to rotate around the hip joint 4 (while the knee joint also rotates synchronously); a first sprocket (not shown in the figure) is fixedly mounted on the lower leg 9, and the output shaft of the knee joint motor 6 is connected to the first sprocket through the first transmission chain to realize the transmission of driving force to the lower leg 9. The first sprocket drives the lower leg 9 to rotate around the knee joint. The drive wheel motor 7 is fixedly installed on the outside of the thigh 8 away from the knee joint motor 6. Its output shaft is connected to the sprocket assembly 13 through the second transmission chain, and the driving force is output to the sprocket assembly 13 through the second transmission chain. However, the sprocket assembly 13 only rotates around the knee joint and does not drive the lower leg 9 to rotate. The foot drive wheel 10 has a second sprocket 101 fixed coaxially. The sprocket assembly 13 is connected to the second sprocket 101 through the third transmission chain, and the third transmission chain is fixedly connected to the ratchet 12. When the drive wheel motor 7 transmits the driving force to the sprocket assembly 13 through the second transmission chain, the sprocket assembly 13 can drive the third transmission chain to drive the ratchet 12 and the second sprocket 101 to rotate, thereby making the foot drive wheel 10 and the ratchet 12 rotate synchronously.

[0079] In this embodiment, the aforementioned thigh 8 is a rectangular frame leg composed of four plates connected end to end. The rectangular frame leg is hollow inside and has a pair of open sides in a hollow shape. The first transmission chain and the second transmission chain are both located inside the thigh 8 and are symmetrically arranged on both sides of the inside of the thigh 8 along the length direction of the pair of side walls. One end of the lower leg 9 is inserted into one end of the thigh 8 and is located between the first transmission chain and the second transmission chain. After the lower leg 9 and the thigh 8 are assembled, they are connected by a hinge. The open surface of the thigh 8 can ensure that the lower leg 9 has sufficient rotation space when rotating around the knee joint, and will not interfere with the thigh 8 or be obstructed in any way.

[0080] In this embodiment, the lower leg 9 is designed as a solid cubic prism to achieve stable movement. The foot drive wheel 10 is installed on the end of the lower leg 9 away from the thigh 8 through a connecting shaft. In other embodiments, the lower leg 9 and thigh 8 can also be set to cylindrical or other shapes, as long as they do not interfere with each other when they rotate relative to each other.

[0081] In this embodiment, the aforementioned sprocket assembly 13 includes two coaxially fixed third sprockets 131. One third sprocket 131 is connected to the drive wheel motor 7 via a second transmission chain, and the other third sprocket 131 is connected to the second sprocket 101 via a third transmission chain. Specifically, a pair of third sprockets 131 are coaxially disposed with the ratchet 12 on the same side of the lower leg 9 near the thigh 8, and the aforementioned first sprocket is installed on different sides of the third sprockets 131.

[0082] In this embodiment, the connecting ends of the first body 1 and the second body 2 are both V-shaped, and the V-shaped tips of the two overlap each other. The stop structure 14 is a V-shaped protrusion provided on the V-shaped tip of the first body 1. When the second body 2 rotates, the two sides of its V-shaped end can abut against the two sides of the V-shaped protrusion. Specifically, a part of the first body is thicker and the remaining part is thinner. The connection between the thicker body and the thinner body forms a V-shaped protrusion.

[0083] In other preferred embodiments, the aforementioned stop structure 14 may also be a ridge, a protrusion, or any other mechanism that can achieve the stopping effect.

[0084] like Figure 1-3 As shown, in this embodiment, the robot's height from the ground increases several times when it moves from a crawling posture to a fully standing posture. This means that compared with robots of the same size, this robot has a stronger ability to crawl through narrow terrain and stand to avoid protruding obstacles.

[0085] like Figure 5 The diagram shows four leg positions of a four-wheeled robot. The right side represents the robot's forward direction. Due to the open, hollow design on the side of the thigh (8), the robot can achieve... Figure 5 The robot displays four different leg configurations: "forward elbow and backward knee," "full knee," "full elbow," and "forward knee and backward elbow." The robot can switch leg configurations according to different road conditions, thus possessing stronger terrain adaptability or stability.

[0086] Furthermore, in this embodiment, the foot drive wheels 10 and the ratchet 12 at the knee joint of the robot rotate in the same direction. The foot drive wheels 10 are suitable for rotating on flat, hard surfaces, enabling the robot to achieve smooth and rapid movements. For rugged, smooth, or steep uphill terrain, the ratchet 12 can be used to rotate on the ground to drive the robot's movement, increasing friction and achieving steady progress. Figure 6 As shown, the four-wheeled robot can also move forward by using a hybrid motion mode in which the ratchet 12 and the foot drive wheel 10 rotate simultaneously, resulting in stronger grip, more driving force, and better stability.

[0087] Example 2

[0088] This embodiment provides a motion method for the four-wheeled legged robot in the aforementioned embodiment 1, including a flat ground walking mode, an obstacle crossing mode, and a posture return mode. Each motion mode will be described in detail below with reference to the accompanying drawings.

[0089] The flat terrain travel mode includes two modes of travel, such as... Figure 1 As shown, the first mode of movement is as follows: with the target direction of movement on the right, control all lower limb structures to lock the angles of the hip joint 4 and knee joint, so that each leg is perpendicular to the body and in a rigid support state, and then the drive wheel motor 7 provides power to drive the foot drive wheel 10 to rotate along the ground to achieve upright movement; the second mode of movement is as follows: Figure 3 As shown, the right side represents the target direction of travel. The hip joint motor 5 controls the thigh 8 to rotate around the hip joint 4, while the knee joint motor 6 controls the lower leg 9 to bend around the knee joint, completely folding all four legs. The drive wheel motor 7 continuously provides power, causing all foot drive wheels 10 and ratchet 12 to rotate simultaneously while remaining in contact with the ground, thus enabling the robot to crawl. Alternatively, as... Figure 6 As shown, by rotating the hip and knee joints, the four legs are bent into a certain position. Figure 5 As shown in Figure a, the robot adopts a "front elbow and back knee" configuration and utilizes the drive wheel motor 7 to continuously provide power so that all the foot drive wheels 10 and ratchet 12 rotate simultaneously while touching the ground, thereby enabling the robot to crawl at a certain height off the ground.

[0090] The obstacle crossing mode includes two obstacle crossing methods. The first obstacle crossing method is as follows: Figure 7 As shown, when the robot detects a low obstacle whose height is lower than the robot's upright height, the robot assumes a certain posture. Figure 7 In the prone position shown in Figure a at a certain height, if the width of the low obstacle is no greater than the length of the lower leg (9), perform the following steps:

[0091] S1 as Figure 7 As shown in Figure b, the lower leg 9 of the front leg that is close to the obstacle is controlled to rotate around the knee joint in a direction away from the ground, so that the corresponding foot drive wheel 10 (i.e., the front leg) is lifted off the ground. At the same time, the drive wheel motor 7 drives the corresponding ratchet 12 to rotate along the ground, thereby driving the robot forward until the foot drive wheel 10 moves forward and crosses the obstacle.

[0092] S2 as Figure 7 As shown in c and d, the lower leg 9 of the foreleg that has crossed the obstacle rotates around the knee joint toward the ground, causing the corresponding foot drive wheel 10 to land and rotate, and causing the corresponding ratchet 12 to leave the ground. The ratchet 12 can passively cross the obstacle under the drive of the other foot drive wheels 10.

[0093] S3 Repeat steps S1 to S2 until all lower limb structures have crossed the obstacle, at which point the robot has completely crossed the obstacle.

[0094] In this embodiment, steps S1-S2 can be performed by the front legs to achieve foot-stepping over the obstacle, or steps S1-S2 can be performed by both front legs and both hind legs simultaneously to achieve synchronous forward movement over the obstacle.

[0095] If the width of the detected low obstacle is greater than the length of the lower leg (i.e., a low ledge or narrow ditch), then perform the following steps:

[0096] C1 as Figure 8 As shown, one foreleg structure (i.e., the foreleg) closest to the narrow ditch serving as a low obstacle rotates around its hip joint to lift the foreleg off the ground; simultaneously, the lower leg 9 of one hind leg structure furthest from the low obstacle rotates forward around its corresponding knee joint, causing its foot drive wheel 10 to move forward to a position below the middle of the fuselage, forming a triangular support area together with the foot drive wheel 10 on the other hind leg and the ratchet 12 of the unlifted foreleg. Figure 9 As shown, this ensures that the robot's center of gravity (i.e., center of mass) is always located within the triangular support area;

[0097] C2 extends the raised foreleg to its maximum extent and rotates it around the corresponding hip joint until the foot drive wheel 10 on it steps onto the flat ground opposite the low obstacle;

[0098] C3 repeats the weight transfer method of steps C1-C2, and sequentially moves the remaining lower limb structures to cross the low obstacle according to steps C1 and C2;

[0099] When a high obstacle higher than the upright height of the quadruped robot is detected, the following steps are performed:

[0100] P1 as Figure 10 As shown in Figure 4a, this is a schematic diagram of the motion state of the four-wheeled leg robot when its front legs climb a high obstacle. First, control one of the two lower limb structures at the front end to rotate around its hip joint 4 and make the lower leg 9 rotate around the knee joint, so as to lift the corresponding foot drive wheel 10 and attach it to the high obstacle; then attach the other front leg to the high obstacle in the same way.

[0101] P2 as Figure 11 As shown in the diagram, all foot drive wheels 10 are controlled to rotate, driving the robot forward and bringing the rear lower limb structure closer to the high obstacle. Specifically, the knee and hip joint motors of the two front legs work together to rotate the corresponding hip and knee joints, raising the front half of the robot body to a height exceeding that of the high obstacle. At the same time, the four drive wheels rotate forward together, continuously raising the robot and bringing the hind legs closer to the step. When the hind legs are close enough to the step, the robot stops moving forward.

[0102] P3 then follows the method of step P1, such as Figure 12As shown in Figure 4a, the hip and knee joints of one hind leg in the rear pair of lower limb structures are controlled to rotate in coordination as indicated by the arrows in the figure. Even if the hip joint rotates in the opposite direction, the hind leg rotates in the opposite direction and is raised. Figure 12 (as shown in ab), until the corresponding foot drive wheel 10 rotates and attaches to the high obstacle ( Figure 12 As shown in c), use the same method to place the other hind leg onto the high obstacle as well. Figure 12 As shown in the middle df), the corresponding knee joints flex, and all foot drive wheels 10 rotate synchronously to lead the whole body forward and complete the robot's overall climbing over the high obstacle.

[0103] In this embodiment, the motion method further includes an attitude recovery mode, which includes a lateral tilt recovery method and a flip recovery method.

[0104] The methods for correcting a lateral tilt include: Figure 13 As shown in Figure ab, this is a schematic diagram of the process of a four-wheeled robot tilting to the side and then righting itself. When the robot is detected to be tilting to the side, the lower limb structure on the side closer to the ground is controlled to retract. The robot then uses the weight of the lower limb structure on the side farther from the ground to flip the robot to the side farther from the ground until the robot returns to a crawling posture. If the weight is insufficient to achieve the flip, the lower limb structure on the side farther from the ground is controlled to perform a retraction and extension action. The inertial torque generated breaks the balance and assists the robot in completing the flip.

[0105] When the robot's back is detected to be touching the ground, such as Figure 14 As shown in the diagram, all lower limb structures are first controlled to retract simultaneously towards the center of the robot body. This involves rotating each thigh 8 around its corresponding hip joint, with the hip joints of the front legs and hind legs rotating in opposite directions. This causes each ratchet 12 to touch the ground, and as each thigh 8 continues to rotate around its hip joint, the robot body is lifted off the ground, transforming the back into the abdomen, thus returning to a prone position. Simultaneously, each knee joint is rotated, causing the lower limb structures to gradually extend until the foot drive wheels touch the ground and support the robot body further away from the ground, thereby allowing the robot to return to a standing position. Due to the high friction between the ratchet 12 and the bottom surface, the grip of each lower limb structure is stronger during the robot body's lift-off process, resulting in a more stable and efficient recovery process.

[0106] In other embodiments, when the robot's back is detected to be on the ground, the hip joints 4 and knee joints of the lower limb structure can be controlled to rotate in opposite directions to achieve a folded state with all legs located on the outside of the body, and each ratchet 12 on the ground. Then, the hip joints 4 of a pair of front legs and a pair of hind legs are continuously rotated in opposite directions on the outside of the body. Under the gripping force provided by each ratchet 12, the body is supported off the ground, so that the original back becomes the abdomen, and the posture is corrected.

[0107] Example 3

[0108] This embodiment provides a hierarchical distributed architecture for the control system used to implement the motion method in Embodiment 2, including sensor components, motion control units, and a central processing unit. The sensor components are deployed on the body and lower limb structure to detect obstacle information around the robot, posture information of the body, and contact information between the foot drive wheels 10 and ratchet 12 and the ground, and transmit all the detected information to the central processing unit. The central processing unit is used to send control commands to the motion control unit based on the detected information. The motion control unit is used to execute corresponding actions based on the control commands to perform a flat ground movement mode or an obstacle crossing mode.

[0109] Specifically, the aforementioned sensor components include: an inertial measurement unit for real-time detection of the robot's posture; a motor encoder for real-time detection of the angles of the hip joint 4 and knee joint, and also for detecting the wheel speeds of the foot drive wheels 10 and ratchet 12; a distance sensor mounted on the robot body for detecting obstacle information around the robot; and a current detection unit mounted on the foot drive wheels 10 and ratchet 12 for detecting current conditions to determine the contact information between the corresponding foot drive wheels 10 and ratchet 12 and the ground.

[0110] More specifically, the aforementioned central processing unit, as the "brain" of the robot, uses a high-performance embedded processor to run upper-level decision-making and planning algorithms; the aforementioned motion control unit uses multiple distributed controllers, each motion control unit is responsible for controlling three drive motors of one leg, and receives instructions from the central processing unit to perform high-frequency, high-precision closed-loop servo control.

[0111] The aforementioned inertial measurement unit is used to sense the pitch, roll, and yaw angular velocities and angles of the fuselage in real time, which is the basis for attitude stabilization and recovery control. The aforementioned motor encoder is set on each drive motor to provide feedback on the angle and wheel speed at each joint, so as to achieve precise position control and speed control. The aforementioned distance sensors are installed at multiple positions on the front, rear, left, and right of the fuselage. Specifically, ultrasonic distance sensors, infrared distance sensors, or lidar distance sensors can be selected to detect terrain information such as the height of obstacles in front and the width of ditches. The aforementioned current detection unit is set at the foot drive wheel 10 and ratchet 12. It can indirectly determine whether the corresponding drive wheel is slipping or in contact with the ground by detecting the current of the corresponding drive motor, providing a basis for gait switching.

[0112] The control system provided in this embodiment can identify the terrain in real time based on the aforementioned sensor information and automatically switch between multiple motion modes, giving full play to the advantages of the robot's mechanical structure.

[0113] When the ground is detected to be flat and hard, the flat ground travel mode is activated: the control system locks all knee and hip joint angles, making the legs a rigid support rod, and the movement is achieved by relying solely on the drive wheel motor. This enables high-speed, low-consumption movement.

[0114] When a slight bump, slope, or loose surface is detected, the obstacle crossing mode is activated: the control system releases the leg lock, the central processing unit calculates the body's desired stable posture based on the data from the inertial measurement unit, the motion control unit coordinates the hip and knee joint motors to perform active suspension adjustment to absorb vibration, and the foot drive wheel 10 provides the main power, while the ratchet 12 assists in anti-slip. This mode balances speed and stability.

[0115] When the distance sensor detects an obstacle or ditch higher than a set threshold (i.e., the robot's own upright height), the robot switches to the climbing mode within the obstacle-crossing mode. The central processing unit generates an obstacle-crossing trajectory based on visual or distance information, and the motion control unit precisely controls the rotation of the hip and knee joint motors on each leg, executing the climbing gait as described in Embodiment 2 above. In this mode, the foot drive wheels 10 and ratchet 12 can provide auxiliary thrust or grip as needed.

[0116] When the control system detects that the height of the space in front is very low, it controls all legs to retract to the limit, so that the robot enters a fully crawling posture. At the same time, the foot drive wheels 10 rotate at low speed to help the robot pass through the low space.

[0117] When the robot's tilt angle exceeds the safety threshold, the central processing unit immediately triggers the robot recovery algorithm. When the robot rolls over, it quickly tightens the leg on the side about to hit the ground (reducing rotational inertia) while fully extending the two legs on the other side. It utilizes the combined force of its gravitational torque and the active force of the drive motors at the joints to achieve a fast and reliable rollover, rather than relying entirely on passive weight.

[0118] When the robot detects that its back has landed, the drive motors controlling the hip joints of its four legs perform a coordinated 360° rotation. Utilizing the large range of motion of its thighs (8) and calves (9), the robot is pushed off the ground like it is "rolling over" until it returns to its normal posture. This process utilizes the infinite rotational capabilities of the hip and knee joints.

[0119] Furthermore, when the robot needs to turn, the central processing unit can calculate the speed difference between the inner and outer wheels based on the target turning radius R mentioned in Embodiment 1, and issue instructions to the motion control unit. Simultaneously, when a drive motor is installed at the hinge of the robot body, the rotation angle θ of the drive motor can be actively controlled to make the robot body shape more consistent with the kinematic model, thereby reducing sideslip and achieving a smaller radius and more stable steering.

[0120] When the robot is climbing steep slopes, the control system dynamically distributes the torque output of the foot drive wheels 10 and ratchet 12 according to the load of each foot drive wheel 10 and ratchet 12 (through feedback from detected current information), to prevent slippage of a single mechanism and achieve maximum climbing ability. This directly utilizes the mechanical design of ratchet and drive wheel transmission in the same direction.

[0121] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0122] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0123] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0124] Furthermore, the mathematical concepts mentioned in the embodiments of this application, such as symmetry, equality, parallelism, and perpendicularity, are limitations specific to the current technological level, rather than absolute and strict mathematical definitions. Slight deviations are permissible; approximations of symmetry, equality, parallelism, and perpendicularity are all acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0125] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of locomotion for a quadrupedal robot, characterized in that, The four-wheel foot robot comprises a body and lower limb structures arranged on both sides of the front and rear ends of the body, and the connection between the lower limb structures and the body forms a hip joint (4). The lower limb structures comprise a driving assembly, a thigh (8), a shank (9) and a foot driving wheel (10). The driving assembly is connected with one end of the thigh (8) and the hip joint (4) respectively, the other end of the thigh (8) is connected with one end of the shank (9) to form a knee joint, and the other end of the shank (9) is connected with the foot driving wheel (10). A sprocket set (13) is arranged at the knee joint, the sprocket set (13) is connected with the driving assembly and the foot driving wheel (10) through a chain transmission structure (11) respectively, and a ratchet wheel (12) is coaxially arranged on the sprocket set (13). The posture righting mode of the four-wheel foot robot is as follows: when it is detected that the robot is laterally tilted, the lower limb structure close to the ground is controlled to be retracted, the robot is turned over to the side away from the ground by the weight of the lower limb structure away from the ground until the body returns to a prone posture; if the weight is insufficient to realize the turning over, the lower limb structure away from the ground is controlled to perform a retracting and releasing action to break the balance by generating an inertial torque and assist the four-wheel foot robot to complete the turning over; when it is detected that the back of the four-wheel foot robot is grounded, all the lower limb structures are controlled to be retracted to a folded state, and then each thigh (8) is rotated around the corresponding hip joint to support the body away from the ground so that the original back becomes an abdomen. The outer diameter of the ratchet wheel (12) is greater than the outer diameter of the sprocket set (13), and the direction of the ratchet teeth on the periphery of the ratchet wheel (12) is opposite to the rotating direction thereof. The driving assembly can drive the thigh (8) to rotate around the hip joint (4), drive the shank (9) to rotate relative to the thigh (8) around the knee joint, make the corresponding foot driving wheel (10) and / or ratchet wheel (12) ground or leave the ground, and simultaneously drive the corresponding sprocket set (13) to rotate, thereby driving the corresponding ratchet wheel (12) and foot driving wheel (10) to rotate in the same direction.

2. The motion method of the four-wheel foot robot according to claim 1, wherein, ​ 3. The method of Claim 1, wherein, The drive assembly comprises a hip joint motor (5), a knee joint motor (6) and a drive wheel motor (7), the chain transmission structure (11) comprises a first transmission chain, a second transmission chain and a third transmission chain, wherein: the hip joint motor (5) is fixedly arranged at the hip joint (4), and the output shaft thereof is fixedly connected with the knee joint motor (6); the knee joint motor (6) is installed on one end of the outer side of the thigh (8) and is used for driving the thigh (8) to rotate around the hip joint (4); the first sprocket is arranged on the lower leg (9), and the output shaft of the knee joint motor (6) is connected with the first sprocket through the first transmission chain, so as to drive the lower leg (9) to rotate around the knee joint; the drive wheel motor (7) is installed on the outer side of the thigh (8) and is arranged opposite to the knee joint motor (6), and the output shaft of the drive wheel motor (7) is connected with the sprocket set (13) through the second transmission chain; the second sprocket (101) is coaxially fixedly arranged on the foot drive wheel (10), the sprocket set (13) is connected with the second sprocket (101) through the third transmission chain, and the drive wheel motor (7) can drive the sprocket set (13) to rotate, thereby driving the second sprocket (101) to drive the foot drive wheel (10) to rotate.

4. The method of Claim 3, wherein, The sprocket set (13) comprises two coaxially fixed third sprockets (131), one of which is connected with the drive wheel motor (7) through the second transmission chain, and the other of which is connected with the second sprocket (101) through the third transmission chain.

5. The method of Claim 1, wherein, The body comprises a first body (1) and a second body (2), the first body (1) and the second body (2) are connected by a hinge to form a waist joint (3); the first body (1) is provided with a stop structure (14), the stop structure (14) is used for limiting the rotation angle of the second body (2) around the waist joint (3).

6. The method of locomotion of a four-wheel foot robot according to claim 5, wherein, The joint end of the first body (1) and the second body (2) is V-shaped, and the V-shaped tips of the two are overlapped, the stop structure (14) is a V-shaped boss arranged at the V-shaped tip of the first body (1), when the second body (2) rotates, the two side edges of the V-shaped end can correspondingly abut against the two side edges of the V-shaped boss.

7. The method of locomotion of the four-wheeled foot robot according to any of claims 1-6, characterized in that, Further comprising: Flat ground travel mode: control all lower limb structures to lock the joint angle to be a rigid support rod, and make the foot drive wheel (10) rotate on the ground to realize upright walking; or, control the knee joint to bend, so that all foot drive wheels (10) and ratchets (12) rotate on the ground at the same time to realize crawling; Obstacle crossing mode: when a low obstacle with a height lower than the upright height of the robot is detected, the four-wheel foot robot assumes a crawling posture, if the width of the low obstacle is not greater than the length of the lower leg (9), the following steps are performed: S1 control the foot drive wheel (10) close to the obstacle to lift off the ground, and make the corresponding ratchet (12) rotate on the ground, drive the four-wheel foot robot to move forward until the foot drive wheel (10) crosses the obstacle; S2 control the foot drive wheel (10) over the obstacle to fall and rotate, and make the corresponding ratchet (12) off the ground, driven by the foot drive wheel (10) to pass the obstacle passively; S3 repeat steps S1-S2 until the four-wheel foot robot completely overcomes the obstacle; If the width of the low obstacle is greater than the length of the lower leg (9), the following steps are performed: C1 make the front lower limb structure close to the low obstacle rotate around its hip joint to lift off the ground; at the same time, make the lower leg (9) of the rear lower limb structure away from the low obstacle rotate, so that the foot drive wheel (10) moves forward to the lower part of the middle of the body, and forms a triangular support area with the other rear foot drive wheel (10) and the ratchet (12) of the unlifted front lower limb structure, and the center of gravity of the four-wheel foot robot is located in the triangular support area; C2 make the lifted front lower limb structure rotate around the corresponding hip joint to the maximum extent until the foot drive wheel (10) thereon steps onto the ground on the other side of the low obstacle; C3 repeat steps C1-C2 to sequentially drive the remaining lower limb structures to cross the low obstacle by center of gravity transfer; When a high obstacle higher than the upright height of the four-wheel foot robot is detected, the following steps are performed: P1 control a pair of front lower limb structures to rotate around the corresponding hip joint (4) respectively to lift the corresponding foot drive wheel (10) high and sequentially lap onto the high obstacle; P2 control all foot drive wheels (10) to rotate to drive the four-wheel foot robot as a whole to move forward, so that the rear lower limb structure approaches the high obstacle; P3 according to the method of step P1, lap the foot drive wheels (10) of the rear pair of lower limb structures onto the high obstacle in sequence to cross the high obstacle.

8. Control system for implementing the movement method according to any one of claims 1-7, characterized in that, The four-wheel foot robot comprises a sensor assembly, a motion control unit and a central processing unit, wherein: the sensor assembly is arranged on the body and the lower limb structure, used for detecting obstacle information around the robot, attitude information of the body, and contact information of the foot drive wheel (10) and the ratchet (12) with the ground, and transmitting all detection information to the central processing unit; the central processing unit is used for sending control instructions to the motion control unit based on the detection information; the motion control unit is used for executing corresponding actions based on the control instructions to execute a flat ground travel mode or an obstacle crossing mode.

9. The control system of claim 8, wherein, The sensor assembly comprises: an inertial measurement unit for detecting the body attitude in real time; a motor encoder for detecting the angles of the hip joint (4) and the knee joint in real time, and also for detecting the wheel speeds of the foot drive wheel (10) and the ratchet (12); a distance sensor arranged on the body, used for detecting obstacle information around the four-wheel foot robot; a current detection unit arranged on the foot drive wheel (10) and the ratchet (12), used for detecting current conditions to judge the contact information of the corresponding foot drive wheel (10) and the ratchet (12) with the ground.

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