A foldable four-wheeled leg obstacle-crossing robot

Abstract

The present invention discloses a foldable four-wheeled leg obstacle-crossing robot, which is composed of a central frame, mechanical legs, a controller, a sensor, a laser radar, an intermediate connecting frame and a plurality of servo motors. The central frame is a square frame structure, and the mechanical legs are symmetrically arranged at the four corners of the central frame, one end of the mechanical leg is connected to the central frame through a transmission shaft, and the other end of the mechanical leg is connected to the driving wheel through a wheel bogie. The servo motors are respectively located at the four corners of the central frame, and the output shaft of the servo motor is fixedly connected to the transmission shaft of the mechanical leg. The intermediate connecting frame is located at the upper part of the central frame, and the laser radar and the acceleration sensor are fixedly connected to the upper part of the intermediate connecting frame. The controller is arranged at the bottom of the central frame, and the controller receives the servo motor and sensor signals, and the controller issues a control instruction, and performs closed-loop control on each servo motor and the driving wheel through the sensor. The robot has a compact structure and strong body stability, and is suitable for high-speed operations under complex terrain conditions.

Description

Technical Field

[0001] The invention relates to the field of robots and automatic control technology, in particular to a foldable four-wheeled legged obstacle-crossing robot. Background Art

[0002] Since the 1960s, extensive research on mobile robots has been carried out at home and abroad. The passive suspension system equipped with existing wheeled or tracked mobile devices makes mobile robots unable to adapt to more complex and rugged natural terrain. The development of science and technology in recent years has shown that leg-foot walking devices have a higher adaptability to rugged terrain. However, the leg-foot mechanism has a slower movement speed, requires a larger energy consumption, and is more complex to control. Combining the characteristics of leg-foot walking with wheeled movement to form a wheel-leg compound robot. It has more movement modes, good terrain adaptability, higher movement speed, stronger movement stability, and more flexible obstacle crossing ability. Therefore, the wheel-leg compound mobile robot is regarded as the most promising high-performance mobile robot.

[0003] Wheel-legged robots have a wide range of applications and are suitable for a variety of occasions: unmanned or semi-automated engineering machinery for accident rescue, mountain transportation, and operations in hazardous environments; military robots for outdoor environments; engineering robots for extraterrestrial ground construction; mobile robots for assisting the elderly and the disabled in urban environments; and mobile robots for agricultural automation. Summary of the invention

[0004] In order to avoid the shortcomings of the prior art, the present invention proposes a foldable four-wheeled legged obstacle-crossing robot. The robot has the characteristics of compact structure, strong mobility and good body stability. The mechanical legs can be folded and stored, and the robot has the ability to travel in all directions. Under unstructured terrain conditions, the posture of the mechanical legs can be adjusted to control the wheel-ground contact force, so that the robot has better ground force and improves the stability of the body. The robot is suitable for high-speed operations under complex terrain conditions.

[0005] The technical solution adopted by the present invention to solve its technical problem is: comprising a central frame, mechanical legs, a controller, a servo motor, an acceleration sensor, a laser radar and an intermediate connecting frame, characterized in that the central frame is a square frame structure, the mechanical legs are symmetrically arranged at the four corners of the central frame, one end of the mechanical leg is connected to the central frame through a transmission shaft, and the other end of the mechanical leg is connected to the driving wheel through a wheel bogie; four groups of servo motors are respectively located on the central frame, and the output shaft of the servo motor is fixedly connected to the transmission shaft; the controller is arranged at the bottom of the central frame, the controller receives signals from the servo motor and the acceleration sensor, the controller issues a control instruction, and performs closed-loop control on each servo motor and the driving wheel through the acceleration sensor;

[0006] The mechanical leg comprises a leg root yaw joint, a leg root connecting rod, a thigh joint, a thigh connecting rod, a knee joint, a knee connecting rod, a calf joint, a calf connecting rod, a wheel steering joint, a wheel bogie, and a driving wheel. The leg root yaw joint comprises a first transmission shaft and a second transmission shaft. The first servo motor output shaft is fixedly connected to the first transmission shaft, and the second transmission shaft is connected to the leg root connecting rod. The first transmission shaft and the second transmission shaft are connected and transmitted through a chain to realize the rotation axis of the leg root yaw joint, and drive the leg root connecting rod, the thigh connecting rod, the knee connecting rod, the calf connecting rod, the wheel bogie, and the driving wheel to swing in the horizontal plane.

[0007] The thigh joint includes a screw slide and a thigh connecting rod, wherein the thigh connecting rods are respectively an upper thigh connecting rod, a middle thigh connecting rod and a lower thigh connecting rod, the screw slide, the middle thigh connecting rod and the upper thigh connecting rod are hinged in pairs to form a triangular structure, and the leg root connecting rod, the upper thigh connecting rod, the lower thigh connecting rod and the inner knee connecting rod are hinged in pairs to form a parallelogram structure; wherein the leg root connecting rod and the inner knee connecting rod are parallel to each other, and the upper thigh connecting rod and the lower thigh connecting rod are parallel to each other, and the second servo motor is connected to the thigh screw to drive the thigh screw to rotate and the screw slide to move up and down, and drive the thigh connecting rod to rotate, so as to realize the rotation of the thigh connecting rod, the knee connecting rod, the calf connecting rod and the wheel bogie in the vertical plane; one end of the thigh screw force sensor is connected to the second servo motor, and the other end is connected to the thigh screw, and the thigh screw force sensor is used to measure the thigh joint force;

[0008] The knee joint is composed of a knee inner link, a knee middle link and a knee outer link, which are hinged in pairs. Rigid springs are placed side by side on the knee middle link, and the knee joint plays a buffering role.

[0009] The calf joint is composed of a calf connecting rod and a calf electric cylinder; the calf connecting rod has two basic units, namely a calf upper connecting rod and a calf lower connecting rod, the calf upper connecting rod and the calf lower connecting rod are parallel to each other, and the knee outer connecting rod, the calf upper connecting rod, the calf lower connecting rod, and the wheel steering outer frame are hinged in pairs to form a parallelogram structure; one end of the calf electric cylinder is hinged to the calf lower connecting rod, and the other end of the calf electric cylinder is hinged to the calf upper connecting rod; the calf electric cylinder is driven by a third servo motor, and the electric cylinder moves linearly to realize the rotation of the calf connecting rod, the wheel bogie, and the driving wheel in the vertical plane; the calf electric cylinder force sensor is installed at the tail end of the calf electric cylinder to measure the calf joint force;

[0010] The wheel steering joint is composed of a third transmission shaft and a fourth transmission shaft. The third transmission shaft is connected to the wheel steering outer frame, and the fourth transmission shaft is connected to the wheel bogie. The fourth servo motor is connected to the third transmission shaft. The axes of the two shafts are perpendicular to and parallel to the horizontal plane. The two transmission shafts are connected by a chain drive to realize the swing of the drive wheel in the horizontal plane.

[0011] The controller controls the servo motors of the mechanical legs to drive the angle values ​​of the leg root yaw joint, thigh joint, and calf joint, can adjust the posture of the mechanical legs, and control the wheel steering joint to change the forward direction of the driving wheel. The driving wheel is integrated with a wheel speed sensor to detect its driving speed.

[0012] The acceleration sensor is arranged on the central frame through an intermediate connecting frame. The acceleration sensor is used to control the posture of the mechanical leg and adjust the posture of the central frame to be placed horizontally.

[0013] The laser radar is installed on the central frame through an intermediate connecting frame, and the laser radar is used to measure the surrounding terrain.

[0014] Beneficial Effects

[0015] The present invention proposes a foldable four-wheeled legged obstacle-crossing robot, which has three motion modes, namely, wheeled motion mode, wheel-leg hybrid motion mode, and leg-foot motion mode. The controller controls the enabling and braking states of the driving wheels, and can conveniently realize the switching between the wheel mode and the leg mode. The wheels are selected from drivable DC motors and equipped with off-road tires, and have multi-terrain omnidirectional motion capabilities. When driving on flat ground, the driving wheels work in an enabled state, and the controller controls the driving wheel speed to realize wheeled motion; the fastest driving speed during wheeled motion can reach 20km / h, so that the four-wheeled legged robot has high-speed maneuverability. When driving on uneven terrain, the driving wheels work in an enabled state, and the controller adjusts the postures of the four legs at the same time according to the wheel-ground contact force calculated by the force sensor to realize wheel-leg hybrid motion. When crossing an obstacle, the driving wheels work in a braking state, and the driving wheels cannot rotate. The controller adjusts the postures of the four mechanical legs to realize leg-foot motion. The three motion modes are judged by the controller based on the laser radar data on the surrounding environment, and finally realize omnidirectional movement and obstacle crossing functions under various road conditions.

[0016] The foldable four-wheeled leg obstacle-crossing robot of the present invention has five active degrees of freedom and one passive degree of freedom for each wheel leg. The mechanical leg has a large working space, and the four-wheeled leg has a compact and foldable structure, which greatly reduces the floor space and is convenient for transportation and storage.

[0017] The control method based on force-position hybrid control can adjust the fuselage to a horizontal posture according to the acceleration sensor in the center of the fuselage. The wheel-ground contact force is calculated by the thigh joint force and the calf joint force, which has better ground contact force and good fuselage stability when driving on uneven roads.

[0018] Since the fuselage platform can be adjusted to a horizontal posture in real time and the space above the fuselage can carry a load platform, the thigh link and calf link of the mechanical leg have a parallel four-bar structure. The basic unit of each link is a truss structure with strong resistance to bending and torsion. It has the ability to carry a load-bearing task platform and can be promoted and applied in various occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following is a further detailed description of a foldable four-wheeled leg obstacle-crossing robot of the present invention in conjunction with the accompanying drawings and implementation modes.

[0020] Figure 1 This is a top view of the foldable four-wheeled and legged obstacle-crossing robot of the present invention.

[0021] Figure 2 This is a front view of the foldable four-wheeled and legged obstacle-crossing robot of the present invention.

[0022] Figure 3 It is a schematic diagram of the mechanical legs of the foldable four-wheeled legged obstacle-crossing robot of the present invention.

[0023] Figure 4 It is a schematic diagram of the wheel steering joint of the foldable four-wheeled legged obstacle-crossing robot of the present invention.

[0024] Figure 5 The figure is a schematic diagram of the folded posture of the mechanical legs of the foldable four-wheeled legged obstacle-crossing robot of the present invention.

[0025] Figure 6 This is a control flow chart of the foldable four-wheeled legged obstacle-crossing robot of the present invention.

[0026] In the picture

[0027] 1. Central frame 2. First mechanical leg 3. Second mechanical leg 4. Third mechanical leg 5. Fourth mechanical leg 6. Controller 7. Acceleration sensor 8. LiDAR 9. Intermediate connecting frame 10. Thigh screw 11. First servo motor 12. Leg root yaw joint 13. Leg root connecting rod 14. Thigh joint 15. Thigh screw force sensor 16. Second servo motor 17. Thigh connecting rod 18. Thigh upper connecting rod 19. Knee inner connecting rod 20. Knee middle connecting rod 21. Knee outer connecting rod 22. Calf Joint 23. Calf connecting rod 24. Third servo motor 25. Calf upper connecting rod 26. Calf electric cylinder 27. Fourth servo motor 28. Fourth transmission shaft 29. Driving wheel 30. Calf lower connecting rod 31. Knee connecting rod 32. Calf electric cylinder force sensor 33. Knee joint 34. Thigh lower connecting rod 35. Thigh middle connecting rod 36. Screw slide 37. Second transmission shaft 38. First transmission shaft 39. Wheel steering joint 40. Third transmission shaft 41. Wheel steering outer frame 42. Wheel bogie DETAILED DESCRIPTION

[0028] This embodiment is a foldable four-wheeled legged obstacle-crossing robot.

[0029] See also Figure 1 to Figure 6The foldable four-wheeled leg obstacle-crossing robot of this embodiment is composed of a central frame 1, mechanical legs, a controller 6, a servo motor, an acceleration sensor 7, a laser radar 8 and an intermediate connecting frame 9; wherein the mechanical legs include a first mechanical leg 2, a second mechanical leg 3, a third mechanical leg 4 and a fourth mechanical leg 5; the servo motor includes a first servo motor 11, a second servo motor 16, a third servo motor 24 and a fourth servo motor 27. The central frame 1 is a square frame structure; the intermediate connecting frame 9 is installed on the upper part of the central frame, and the laser radar 8 and the acceleration sensor 7 are fixedly connected to the upper part of the intermediate connecting frame 9; the mechanical legs are symmetrically arranged at the four corners of the central frame, one end of the mechanical leg is connected to the central frame through a transmission shaft, and the other end of the mechanical leg is connected to the driving wheel 29 through a wheel bogie 42; four groups of servo motors are respectively installed on the central frame, and the output shaft of the servo motor is fixedly connected to the transmission shaft. The controller 6 is arranged at the bottom of the central frame 1, and the controller 6 receives the signals of the servo motor and the acceleration sensor 7, and the controller 6 issues a control instruction, and performs closed-loop control on each servo motor and the driving wheel through the acceleration sensor 7.

[0030] In this embodiment, the mechanical leg also includes a leg root lateral swing joint 12, a leg root connecting rod 13, a thigh joint 14, a thigh connecting rod 17, a knee joint 33, a knee connecting rod 31, a calf joint 22, a calf connecting rod 23, a wheel steering joint 39, a wheel bogie 42, and a driving wheel 29; the leg root lateral swing joint 12 includes a first transmission shaft 38 and a second transmission shaft 37, the output shaft of the first servo motor 11 is fixedly connected to the first transmission shaft 38, the second transmission shaft is connected to the leg root connecting rod 13, and the first transmission shaft 38 and the second transmission shaft 37 are connected and transmitted through a chain to realize the rotation axis of the leg root lateral swing joint 12 and drive the leg root connecting rod 13, the thigh connecting rod 17, the knee connecting rod 31, the calf connecting rod 23, the wheel bogie 42, and the active driving wheel 29 to swing in the horizontal plane.

[0031] The thigh joint 14 includes a screw slide 36 and a thigh connecting rod 17. The thigh connecting rods are respectively an upper thigh connecting rod 18, a middle thigh connecting rod 35 and a lower thigh connecting rod 34. The screw slide 36, the middle thigh connecting rod 35 and the upper thigh connecting rod 18 are hinged in pairs to form a triangular structure; the leg root connecting rod 13, the upper thigh connecting rod 18, the lower thigh connecting rod 34 and the inner knee connecting rod 19 are hinged in pairs to form a parallelogram structure. Among them, the leg root connecting rod 13 and the inner knee connecting rod 19 are parallel to each other, and the upper thigh connecting rod 18 and the lower thigh connecting rod 34 are parallel to each other; the second servo motor 16 is connected to the thigh screw 10, driving the thigh screw 10 to rotate and the screw slide 36 to move up and down, and driving the thigh connecting rod 17 to rotate, so as to realize the rotation of the thigh connecting rod 17, the knee connecting rod 31, the calf connecting rod 23 and the wheel bogie 42 in the vertical plane. One end of the thigh screw force sensor 15 is connected to the second servo motor 16, and the other end is connected to the thigh screw 10, and is used to measure the thigh joint force.

[0032] The knee joint 33 is composed of a knee inner link 19, a knee middle link 20 and a knee outer link 32 which are hinged in pairs; rigid springs are placed side by side on the knee middle link, and the knee joint 33 plays a buffering role.

[0033] The calf joint 22 is composed of a calf connecting rod 23 and a calf electric cylinder 26; the calf connecting rod has two basic units, namely the calf upper connecting rod 25 and the calf lower connecting rod 30, and the calf upper connecting rod 25 and the calf lower connecting rod 30 are parallel to each other; the knee outer connecting rod 21, the calf upper connecting rod 25, the calf lower connecting rod 30, and the wheel steering outer frame 41 are hinged in pairs to form a parallelogram structure. One end of the calf electric cylinder 26 is hinged to the calf lower connecting rod 30, and the other end of the calf electric cylinder 26 is hinged to the calf upper connecting rod 25. The calf electric cylinder 26 is driven by the third servo motor 24, and the electric cylinder moves linearly to realize the rotation of the calf connecting rod 23, the wheel bogie 42, and the driving wheel 29 in the vertical plane. The calf electric cylinder force sensor 32 is installed at the tail end of the calf electric cylinder 26 to measure the calf joint force.

[0034] The wheel steering joint 39 is composed of a third transmission shaft, a fourth transmission shaft 28 and a fourth servo motor 27. The third transmission shaft 40 is fixedly connected to the wheel steering outer frame 41, and the fourth transmission shaft 28 is fixedly connected to the wheel bogie 42. The fourth servo motor 27 is connected to the third transmission shaft 40, and the axes of the two shafts are perpendicular to and parallel to the horizontal plane. The third transmission shaft 40 and the fourth transmission shaft 28 are connected by chain drive to realize the swing of the drive wheel in the horizontal plane.

[0035] The controller 6 controls the servo motors of the mechanical legs to drive the leg root yaw joint 12, thigh joint 14, and calf joint 22 to adjust the angle value of the mechanical leg posture, and controls the wheel steering joint 39 to change the forward direction of the driving wheel 29. The driving wheel 29 is integrated with a wheel speed sensor to detect its driving speed.

[0036] The acceleration sensor 7 is arranged at the middle part of the central frame through the middle connecting frame 9. The acceleration sensor 7 is used to control the posture of the mechanical leg and adjust the posture of the central frame to be placed horizontally.

[0037] The laser radar 8 is installed on the central frame through the intermediate connecting frame 9. The laser radar is used to measure the surrounding terrain.

[0038] This embodiment is described by taking the first mechanical leg 2 as an example, wherein the controller 6 receives the signals of the thigh screw force sensor 15 and the calf electric cylinder force sensor 32, obtains the calculated wheel-ground contact force, and compares the calculated wheel-ground contact force with the expected wheel-ground contact force redistributed by the model. The controller 6 receives the pulse number of each servo motor, controls the motor position, controls the first servo motor 11 to rotate, realizes the rotation of the leg root lateral swing joint 12 in the horizontal plane, and makes the leg root lateral swing joint 12 reach the expected angle value. The second servo motor 16 is controlled to rotate, realizes the rotation of the thigh joint 14 in the vertical plane, and makes the thigh joint 14 reach the expected angle value. The third servo motor 24 is controlled to rotate, and the calf joint 22 is controlled to rotate in the vertical plane, and makes the calf joint 22 reach the expected angle value. Control the fourth servo motor 28 to rotate, realize the rotation of the wheel steering joint 39 in the horizontal plane, make the wheel steering joint 39 reach the desired angle value, realize the posture control of the mechanical leg, make the mechanical leg wheel contact force equal to the desired wheel contact force, realize the control of the driving wheel 29 contact force, and make the mechanical leg movement have better compliance.

[0039] The controller 6 receives data from the acceleration sensor 7, and controls the postures of the first mechanical leg 2, the second mechanical leg 3, the third mechanical leg 4, and the fourth mechanical leg 5 to keep the body posture horizontal, and performs force-position hybrid control to ensure that the central frame 1 has better horizontal stability during driving.

[0040] When the robot stops working, controller 6 controls the thigh joint to 3 degrees, at which time the angle between the thigh connecting rod and the upper vertical plane is 3 degrees; controls the calf joint to 177 degrees, at which time the angle between the calf connecting rod and the upper vertical plane is 177 degrees; controls the root joint to 135 degrees, at which time the mechanical leg is parallel to the side of the central frame, so that the four-wheeled legged robot can be folded and stored.

[0041] The foldable four-wheeled legged obstacle-crossing robot of this embodiment has three motion modes, namely, wheeled motion mode, wheel-leg hybrid motion mode, and leg-foot motion mode. In the three motion modes, the controller 6 makes a judgment on the surrounding environment according to the data of the laser radar 8. The controller 6 controls the enabling and braking state of the driving wheel 29, and can easily realize the conversion between the wheel mode and the leg mode; and realizes the omnidirectional movement and obstacle-crossing function under various road conditions.

[0042] Working steps

[0043] (1) The controller 6 receives data from various sensors and servo motors to confirm whether the robot is in the folded state. If so, it controls the postures of the first mechanical leg 2, the second mechanical leg 3, the third mechanical leg 4, and the fourth mechanical leg 5, adjusts the posture of the central frame 1 to a horizontal state, and adjusts the angle of the mechanical leg wheel steering joint 39 to ensure that the robot has omnidirectional motion capability and can continue to receive motion instructions.

[0044] (2) The controller 6 receives data from the laser radar 8, scans the on-site environment, determines the wheeled, leg-footed, or wheel-leg hybrid motion mode, adjusts the posture of the central frame 1 to a horizontal state, adjusts the angle of the mechanical leg wheel steering joint 39 to ensure omnidirectional motion capability, and can continue to accept motion instructions.

[0045] (3) After placing a load on the robot, the controller 6 receives data from the acceleration sensor 7, controls the posture of the four mechanical legs, adjusts the posture of the central frame 1 to a horizontal state, adjusts the angle of the mechanical leg wheel steering joint 39 to ensure omnidirectional movement capability, and can continue to accept movement instructions.

[0046] (4) When an obstacle appears during the robot's motion, the controller 6 determines whether the obstacle can be crossed based on the workspace. If it is determined that the obstacle cannot be crossed, the controller 6 controls the angle of the mechanical leg wheel steering joint 39 to bypass the obstacle. If it is determined that the obstacle can be crossed, the controller 6 controls the posture and end position of the first mechanical leg 2, the second mechanical leg 3, the third mechanical leg 4, and the fourth mechanical leg 5 to cross the obstacle through foot-type motion. The controller 6 adjusts the posture of the central frame 1 to a horizontal state, adjusts the angle of the mechanical leg wheel steering joint 39 to ensure that the robot has omnidirectional motion capability, and can continue to receive motion instructions.

[0047] (5) After the robot stops moving, the controller 6 controls the posture and end position of the first mechanical leg 2, the second mechanical leg 3, the third mechanical leg 4, and the fourth mechanical leg 5, and folds the wheel-legged mobile platform to the mechanical leg folded posture.

Claims

1. A foldable four-wheeled legged obstacle-crossing robot, comprising a central frame, mechanical legs, a controller, a servo motor, an acceleration sensor, a laser radar and an intermediate connecting frame, characterized in that : The central frame is a square frame structure, the mechanical legs are symmetrically arranged at the four corners of the central frame, one end of the mechanical leg is connected to the central frame through a transmission shaft, and the other end of the mechanical leg is connected to the driving wheel through a wheel bogie; four groups of servo motors are respectively located on the central frame, and the servo motor output shaft is fixedly connected to the transmission shaft; the controller is arranged at the bottom of the central frame, the controller receives the servo motor and the acceleration sensor signal, the controller issues a control instruction, and performs closed-loop control on each servo motor and the driving wheel through the acceleration sensor; The mechanical leg comprises a leg root yaw joint, a leg root connecting rod, a thigh joint, a thigh connecting rod, a knee joint, a knee connecting rod, a calf joint, a calf connecting rod, a wheel steering joint, a wheel bogie, and a driving wheel. The leg root yaw joint comprises a first transmission shaft and a second transmission shaft. The first servo motor output shaft is fixedly connected to the first transmission shaft, and the second transmission shaft is connected to the leg root connecting rod. The first transmission shaft and the second transmission shaft are connected and transmitted through a chain to realize the rotation axis of the leg root yaw joint, and drive the leg root connecting rod, the thigh connecting rod, the knee connecting rod, the calf connecting rod, the wheel bogie, and the driving wheel to swing in the horizontal plane. The thigh joint includes a screw slide and a thigh connecting rod, wherein the thigh connecting rods are respectively an upper thigh connecting rod, a middle thigh connecting rod and a lower thigh connecting rod, the screw slide, the middle thigh connecting rod and the upper thigh connecting rod are hinged in pairs to form a triangular structure, and the leg root connecting rod, the upper thigh connecting rod, the lower thigh connecting rod and the inner knee connecting rod are hinged in pairs to form a parallelogram structure; wherein the leg root connecting rod and the inner knee connecting rod are parallel to each other, and the upper thigh connecting rod and the lower thigh connecting rod are parallel to each other, and the second servo motor is connected to the thigh screw to drive the thigh screw to rotate and the screw slide to move up and down, and drive the thigh connecting rod to rotate, so as to realize the rotation of the thigh connecting rod, the knee connecting rod, the calf connecting rod and the wheel bogie in the vertical plane; one end of the thigh screw force sensor is connected to the second servo motor, and the other end is connected to the thigh screw, and the thigh screw force sensor is used to measure the thigh joint force; The knee joint is composed of a knee inner link, a knee middle link and a knee outer link, which are hinged in pairs. Rigid springs are placed side by side on the knee middle link, and the knee joint plays a buffering role. The calf joint is composed of a calf connecting rod and a calf electric cylinder; the calf connecting rod has two basic units, namely a calf upper connecting rod and a calf lower connecting rod, the calf upper connecting rod and the calf lower connecting rod are parallel to each other, and the knee outer connecting rod, the calf upper connecting rod, the calf lower connecting rod, and the wheel steering outer frame are hinged in pairs to form a parallelogram structure; one end of the calf electric cylinder is hinged to the calf lower connecting rod, and the other end of the calf electric cylinder is hinged to the calf upper connecting rod; the calf electric cylinder is driven by a third servo motor, and the electric cylinder moves linearly to realize the rotation of the calf connecting rod, the wheel bogie, and the driving wheel in the vertical plane; the calf electric cylinder force sensor is installed at the tail end of the calf electric cylinder to measure the calf joint force; The wheel steering joint is composed of a third transmission shaft and a fourth transmission shaft, the third transmission shaft is connected to the wheel steering outer frame, and the fourth transmission shaft is connected to the wheel bogie; the fourth servo motor is connected to the third transmission shaft, the axes of the two shafts are perpendicular to and parallel to the horizontal plane, and the two transmission shafts are connected by a chain drive to realize the swing of the drive wheel in the horizontal plane; The controller controls the servo motors of the mechanical legs to drive the angle values ​​of the leg root yaw joint, thigh joint, and calf joint, and can adjust the posture of the mechanical legs, and control the wheel steering joint to change the forward direction of the driving wheel. The driving wheel is integrated with a wheel speed sensor to detect its driving speed; The acceleration sensor is arranged on the central frame through an intermediate connecting frame. The acceleration sensor is used to control the posture of the mechanical leg and adjust the posture of the central frame to be placed horizontally.

2. The foldable four-wheeled legged obstacle-crossing robot according to claim 1, characterized in that :The laser radar is installed on the central frame through an intermediate connecting frame, and the laser radar is used to measure the surrounding terrain.

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