Wheel-legged hybrid robot and passive obstacle sensing method thereof

Abstract

The application provides a wheel-foot composite robot and a passive obstacle sensing method thereof, wherein the robot comprises a body, a joint motor set, a crank four-bar linkage mechanism, a shank linkage and a wheel-foot unit; the crank four-bar linkage mechanism comprises a thigh linkage, a thigh auxiliary linkage, a driving linkage and a knee joint linkage; the first ends of the thigh linkage and the thigh auxiliary linkage are respectively connected with the end motor stators of the joint motor set; the driving linkage is connected with the end motor rotor of the joint motor set; the first end of the knee joint linkage is connected with the crank rotating shaft of the driving linkage; the second ends of the thigh linkage, the thigh auxiliary linkage and the knee joint linkage are respectively connected with the rotating shafts at the corresponding positions of the first end of the shank linkage; the wheel-foot unit is connected at the second end of the shank linkage; and the front end motor stator of the joint motor set is connected with the body. In this way, the wheel-foot leg part can be switched among the modes of knee bending, lying, swinging and standing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of robots, in particular to a wheel-foot composite robot and a passive obstacle sensing method thereof. BACKGROUND

[0002] With the continuous progress of social technology, the robot technology has also developed rapidly, and the overall demand for robots in society is also increasing. Whether in the industrial field, the agricultural field, or even in the military field, robots have great development and application potential. In order to improve the flexibility of robots, expand their application fields, and reduce energy consumption, more and more different forms of mobile robots are being studied by researchers as platforms and objects.

[0003] At present, most of the mainstream mobile robots are wheeled robots, and the legged robots are also a relatively mainstream research direction in colleges and universities and research institutes. Both of these two forms of robots have their own advantages and disadvantages. Wheeled robots can achieve low-power and high-efficiency movement on relatively flat terrain due to the rolling drive of wheels, but wheeled robots do not have the ability to cross obstacles in complex terrain, and their range of activities will be severely limited in some application scenarios. Compared with wheeled robots, legged robots have good terrain adaptability and can achieve relatively stable movement in complex terrain. However, the foot movement state is discrete and not continuous, which leads to slow movement speed and complex control algorithm, and the efficiency and energy utilization rate of movement on flat terrain are far inferior to wheeled robots.

[0004] Therefore, in order to realize a robot scheme that can simultaneously satisfy the functions of efficient movement on flat ground and obstacle crossing, the inventors consider combining the application characteristics of wheeled robots and legged robots, so that the robot can not only have the ability to efficiently roll on flat ground, but also have the obstacle crossing ability that pure wheeled robots do not have, so that the robot can exhibit good movement ability in various movement environments. SUMMARY

[0005] Therefore, the main purpose of the present application is to provide a wheel-foot composite robot and a passive obstacle sensing method thereof, to design the wheel-foot leg structure based on bionics, so as to support the switching of the wheel-foot leg between the modes of knee flexion, lying, swinging and standing, to adapt to the needs of wheel driving and cross-foot obstacle crossing scenes.

[0006] To achieve the above object, according to a first aspect of the present application, a wheel-foot hybrid robot is provided, comprising: a body, a joint motor set, a crank four-bar linkage, a shank linkage, a wheel-foot unit, wherein the crank four-bar linkage comprises: a thigh linkage, a thigh auxiliary linkage, a driving linkage, a knee joint linkage, the first ends of the thigh linkage and the thigh auxiliary linkage are connected with the end motor stators of the joint motor set respectively, the driving linkage is connected with the end motor rotor of the joint motor set, the first end of the knee joint linkage is connected with the crank pivot of the driving linkage, the second ends of the thigh linkage, the thigh auxiliary linkage and the knee joint linkage are pivotally connected with the first end of the shank linkage respectively, the wheel-foot unit is connected with the second end of the shank linkage, and the front end motor stator of the joint motor set is connected with the body.

[0007] In a possible preferred embodiment, the joint motor set comprises: a hip joint first motor, a hip joint second motor, a hip second mounting base, a hip first mounting base, a knee mounting base, a knee joint motor, the stator of the hip joint first motor is connected with the body through the hip first mounting base, the transverse side of the hip second mounting base is connected with the stator of the hip joint second motor, and the longitudinal side of the hip second mounting base is connected with the rotor of the hip joint first motor, the stator of the knee joint motor is connected with the rotor of the hip joint second motor through the knee mounting base, and the first ends of the thigh linkage and the thigh auxiliary linkage are connected with the stator of the knee joint motor respectively.

[0008] In a possible preferred embodiment, the joint motor set further comprises: a first shock absorber, comprising: a mounting ring, a support, a first spring, wherein the spring is fixed on one side of the mounting ring through the support, and the first end of the thigh linkage is connected with the mounting ring, wherein when the joint motor set drives the crank four-bar linkage to perform a knee-bending and prone action to about the limit, the first spring is in abutment with the shank linkage.

[0009] In a possible preferred embodiment, the wheel-foot hybrid robot further comprises: a second shock absorber, comprising: a support base, a second spring, wherein the second spring is connected with the body at a first position through the support base, and wherein when the joint motor set drives the crank four-bar linkage to perform a knee-bending and prone action to about the limit, the second spring is in abutment with the thigh linkage.

[0010] In a possible preferred embodiment, the wheel-foot unit comprises: a steering motor, a mounting base, a shank base, a driving motor, a wheel, wherein the driving end of the driving motor is connected with the wheel, the transverse side of the mounting base is connected with the driving motor, and the longitudinal side of the mounting base is connected with the driving end of the steering motor, and the steering motor is connected with the second end of the shank linkage through the shank base.

[0011] In a possible preferred embodiment, the wheel-foot unit includes: a wheel, a drive motor, a wrist joint, a lower leg base, a linear actuator, a first rotary joint, and a second rotary joint. The drive motor is fixed to a first side of the wrist joint, and the drive motor transmission end is connected to the wheel. The lower leg base is connected to the wrist joint shaft. A rudder extends outward from a second side of the wrist joint. A bracket extends outward from a third end of the lower leg link. The first end of the linear actuator is hinged to the lower leg link bracket via the first rotary joint, and the second end is hinged to the rudder via the second rotary joint. The second end of the lower leg link is connected to the lower leg base.

[0012] In a possible preferred embodiment, the first rotary joint includes: a first joint and a second joint, wherein the first joint is Z-shaped, with a first longitudinal fork on its first side and a second side fixed to a bracket; the second joint is U-shaped fork, with a longitudinal shaft hole on its concave side and a transverse shaft hole near the fork head; the second joint is connected to the first longitudinal fork shaft of the first joint via the longitudinal shaft hole; and the fork head of the second joint is connected to the first end shaft of the linear actuator via the transverse shaft hole, so as to establish a hinge with two degrees of freedom between the linear actuator and the lower leg connecting rod.

[0013] In a possible preferred embodiment, the second rotary joint includes a third joint and a fourth joint, wherein the third joint is U-shaped fork-like, with a longitudinal shaft hole on its concave side and a transverse shaft hole near the fork head; the fourth joint has a second longitudinal shaft fork and a third longitudinal shaft fork at its two ends, and the second longitudinal shaft fork and the third longitudinal shaft fork are inclined to each other; the fourth joint is pivotally connected to the longitudinal shaft hole of the third joint via the second longitudinal shaft fork; the fourth joint is pivotally connected to the rudder stick via the third longitudinal shaft fork; and the third joint is pivotally connected to the second end of the linear actuator via the transverse shaft hole at the fork head, so as to establish a three-degree-of-freedom hinge between the linear actuator and the rudder stick.

[0014] Corresponding to the aforementioned wheel-legged hybrid robot, a second aspect of the present invention also provides a passive obstacle-crossing method for controlling any of the wheel-legged hybrid robots described above, the steps of which include:

[0015] Step S100 When the drive motor of the sensing wheel unit is obstructed, record the current position P0 (x0, y0, z0) of the wheel relative to the machine body, and stop the drive motor;

[0016] Step S200 starts at P0, causing the joint motor unit to drive the crank four-bar linkage, lower leg linkage, and wheel unit to lift the leg upward in an arc trajectory until the wheel contacts the obstacle, which is recorded as position P1 (x1, y1, z1). The approximate slope θ of the obstacle is calculated based on the position of the wheel.

[0017] ;

[0018] Step S300: Plan the leg-lifting trajectory based on the slope θ, causing the wheel to move along the slope while lifting the leg, and repeat steps S100 to S300 until the slope θ is close to 0°, then record the current wheel position as P. f (xf, yf, zf).

[0019] Step S400 according to P f Together with P0, calculate the obstacle height H and width L, H = zf - z0, L = xf - x0, to plan the leg-lifting trajectory of the remaining wheel-foot units from P0 to P0. f .

[0020] In a possible preferred embodiment, in step S300, when the wheel moves along the slope while the leg is lifted, the drive motor is started to drive the wheel to rotate at the same speed as the leg is lifted.

[0021] The present invention provides a wheel-legged hybrid robot and its passive perception obstacle-crossing method, proposing a wheel-legged hybrid structure that rationally combines the advantages of wheeled and legged robots. It cleverly uses joint motor units, crank four-bar linkages, and lower leg linkages to mimic the hip and knee joint structures and power transmission of biological organisms. This allows the robot's wheel-legged leg structure to freely switch between multiple modes, such as upright walking, knee-bent prone, wheeled driving, and wheel-legged hybrid mode, to select the most suitable movement mode according to the terrain. This enables efficient flat-ground movement and obstacle-crossing ability in complex environments, truly possessing highly efficient all-terrain adaptability.

[0022] From the perspective of the design structure of the wheel-legged composite robot, this invention cleverly utilizes the technology that the wheel-driven motor can sense obstruction by sensing changes in current / voltage. Combined with the unique wheel-leg structure of this invention, which enables the wheels to traverse, it passively senses terrain obstacles, thereby realizing the unique sensing and obstacle-crossing functions of the wheel-legs of this invention. It is evident that compared with existing technologies that require mapping using LiDAR or visual analysis for obstacle perception and subsequent obstacle-crossing trajectory calculation, this implementation scheme is more ingenious and simpler, and has a lower implementation cost. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0024] Figures 1-2 This is a schematic diagram of the overall structure of the wheel-legged composite robot of the present invention, wherein the robot is in a wheeled operation mode with its knees bent and lying down;

[0025] Figure 3A schematic diagram of the wheel-legged composite robot of the present invention is shown in the state of the forelegs being bent and the hindlegs being standing.

[0026] Figure 4 This is an assembly diagram of the wheel and leg structure of the wheel-leg composite robot of the present invention;

[0027] Figures 5-6 This is a schematic diagram of the wheel-leg unit with a design mimicking the radius and ulna rotational wrist joint in the wheel-leg composite robot of the present invention.

[0028] Figure 7 This is an assembly diagram of the wheel-leg unit designed to mimic the radius and ulna rotational wrist joint in the wheel-leg composite robot of the present invention;

[0029] Figure 8 This is a schematic diagram of the overall wheel-foot leg structure of the wheel-foot unit with a design that mimics the radius and ulna rotational wrist joint in the wheel-foot composite robot of the present invention.

[0030] Figure 9 A schematic diagram of the skeletal structure of the human arm and wrist during wrist rotation;

[0031] Figure 10 This is a schematic diagram illustrating the steps of the passive obstacle-crossing method of the present invention;

[0032] Figures 11-12 This is a schematic diagram illustrating the obstacle-crossing process of the passive sensing obstacle-crossing method of the present invention.

[0033] Explanation of reference numerals in the attached figures

[0034] 1. Body, 2. Joint motor assembly, 3. Crank four-bar linkage, 4. Lower leg linkage, 5. Wheel and foot unit, 6. LiDAR, 7. Depth camera, 8. Ultrasonic radar, 31. Thigh linkage, 32. Thigh auxiliary linkage, 33. Drive linkage, 34. Knee joint linkage, 33. Crank, 21. Hip joint first motor, 22. Hip joint second motor, 23. Hip second mounting seat, 24. Hip first mounting seat, 25. Knee mounting seat, 26. Knee joint motor, 27. Mounting ring, 28. Support component, 9. A spring 29, a bracket 50, a steering motor 51, a mounting base 52, a lower leg base 53, a drive motor 54, a wheel 55, a wrist joint 56, a rudder stick 561, an anti-loosening shaft 562, an angle sensor 563, a thrust bearing 564, a linear actuator 57, a first rotary joint 58, a second rotary joint 59, a support base 11, a second spring 12, a first joint 581, a second joint 582, a third joint 591, a fourth joint 592, and an obstacle 9. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element 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 invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0039] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "lay out," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances and in conjunction with existing technology. Furthermore, unless otherwise specified, the embodiments and features in the embodiments of this invention can be combined with each other. One or more of the components shown in the figures may be necessary or not, and the relative positional relationships between the components shown in the figures can be adjusted according to actual needs.

[0041] Please see Figures 1-4 As shown, in order to realize the design of a biomimetic wheel-leg structure that supports the switching between bent-knee prone, swinging, and standing modes to adapt to the needs of wheeled drive and obstacle crossing scenarios, this invention provides a wheel-leg hybrid robot, which includes: a body 1, a joint motor assembly 2, a crank four-bar linkage 3, a lower leg linkage 4, and a wheel-leg unit 5. In terms of design, the key motor assembly mainly realizes the imitation of a human hip joint structure, while the crank four-bar linkage 3 mainly realizes the imitation of a biological knee joint and the transmission of power.

[0042] Specifically, such as Figure 4 As shown, the crank-four-bar linkage 3 includes: a thigh link 31, a thigh auxiliary link 32, a drive link 33, and a knee joint link 34. The first ends of the thigh link 31 and the thigh auxiliary link 32 are respectively connected to the end motor stator of the joint motor assembly 2. The drive link 33 is connected to the end motor rotor of the joint motor assembly 2. The first end of the knee joint link 34 is connected to the crank 331 shaft of the drive link 33. The second ends of the thigh link 31, the thigh auxiliary link 32, and the knee joint link 34 are respectively connected to the shafts at corresponding positions on both sides of the first end of the lower leg link 4. The wheel foot unit 5 is connected to the second end of the lower leg link 4. The front motor stator of the joint motor assembly 2 is connected to the machine body 1.

[0043] Furthermore, the joint motor assembly 2 includes: a first hip joint motor 21, a second hip joint motor 22, a second hip mounting base 5223, a first hip mounting base 5224, a knee mounting base 5225, and a knee joint motor 26. The stator of the first hip joint motor 21 is connected to the body 1 via the first hip mounting base 5224. The second hip mounting base 5223 is connected to the stator of the second hip joint motor 22 on its lateral side and to the rotor of the first hip joint motor 21 on its longitudinal side. The stator of the knee joint motor 26 is connected to the rotor of the second hip joint motor 22 via the knee mounting base 5225. The first ends of the thigh connecting rod 31 and the thigh auxiliary connecting rod 32 are respectively connected to the stator of the knee joint motor 26. The drive connecting rod 33 is connected to the rotor of the knee joint motor 26.

[0044] Therefore, the rotation of the rotor of the first hip joint motor 21 enables the entire leg to swing left and right. The rotor of the second hip joint motor 22 drives the second hip mounting base 5223 to achieve a 90-degree axis switch. Simultaneously, since the rotor of the second hip joint motor 22 is connected to one side of the knee mounting base 5225, and the stator of the knee joint motor 26 is connected to the other side of the knee mounting base 5225, when the knee joint motor 26 is not rotating, the rotation of the second hip joint motor 22 can drive the entire lower leg to swing back and forth.

[0045] Furthermore, since the stator of the knee joint motor 26 is connected to the thigh linkage 31 and the thigh auxiliary linkage 32, and the rotor of the knee joint motor 26 is linked to the knee joint linkage 34 via the drive linkage 33, it can drive the lower leg linkage 4 to achieve the swinging of the lower leg. Thus, the drive linkage 33, the knee joint linkage 34, the thigh linkage 31, and the lower leg linkage 4 together form a crank-connecting four-bar linkage mechanism, realizing the transmission of power to the knee joint, thereby supporting the switching of the bionic wheel-foot leg structure between upright walking and knee-flexed prone modes.

[0046] Furthermore, such as Figures 3-4 As shown, in this example, the wheel and foot unit 5 includes: a steering motor 51, a mounting base 52, a lower leg base 53, a drive motor 54, and a wheel 55. The drive motor 54 is connected to the wheel 55 at its transmission end. The mounting base 52 is connected to the drive motor 54 on its lateral side and to the drive motor 51 on its longitudinal side. The steering motor 51 is connected to the second end of the lower leg connecting rod 4 via the lower leg base 53.

[0047] Thus, through the wheel-leg structure of the example above, the rotation angle of the wheel 55 can be controlled by manipulating the steering motor 51 (such as a stepper motor), thereby enabling the wheel-leg composite robot to achieve independent rotation by relying on the wheel structure on each bionic leg structure when performing wheeled motion, thereby supporting the robot to achieve modes such as Ackerman steering, turning in place, diagonal driving, and arc turning.

[0048] Furthermore, it is worth mentioning that the biomimetic structure of the wheel leg in the above example, due to its layered structure design and the fact that all connecting rod components are flattened, has a small overall volume and is lightweight, with extension and folding capabilities. Moreover, the layered structure design makes its outer surface more impact-resistant.

[0049] On the other hand, when the aforementioned bionic wheeled leg structure transitions to a knee-bent prone mode and uses wheels 55 for travel, the connection between the third end of the lower leg link 4 and the thigh link 31, thigh auxiliary link 32, and knee joint link 34 is easily subjected to force and vibration under bumpy road conditions, thereby affecting the lifespan and reliability of the knee joint structure at this point.

[0050] Therefore, such as Figure 1 and Figure 4 As shown, in this example, the joint motor assembly 2 may further include: a first shock absorber, which includes: a mounting ring 27, a support member 28, and a first spring 29, wherein the spring is fixed to one side of the mounting ring 27 via the support member 28, the mounting ring 27 is connected to the first end of the thigh link 31, wherein when the joint motor assembly 2 drives the crank four-bar linkage 3 to perform a knee-bending prone position to approximately the limit, the first spring 29 abuts against the lower leg link 4.

[0051] Therefore, the first shock absorber can serve as a safety device for the lower leg linkage 4 in the extreme position of the knee-bent prone posture, and can also be used for shock absorption when using wheeled driving mode.

[0052] Furthermore, considering that the joint motor assembly 2 and the thigh linkage 31 will also be subject to vibrations caused by the bumps of the wheel 55 during travel in the knee-bent prone mode, and may even cause impact damage to the thigh linkage 31, therefore, as Figures 1-3 As shown in this example, the wheel-legged composite robot further includes a second shock absorber, which includes a support base 11 and a second spring 12. The second spring 12 is distributed and connected to the first position of the body 1 via the mounting base 52, so that when the joint motor group 2 drives the crank four-bar linkage 3 to perform a knee-bending and prone movement to about the limit, the second spring 12 abuts against the thigh linkage 31.

[0053] Therefore, the second shock absorber can serve as a safety device for the thigh link 31 in the extreme position of the knee-bent prone posture, and can also be used for shock absorption when using wheeled driving mode, thereby reducing vibration at the hip joint.

[0054] More importantly, such as Figure 1 Figure 2As shown, when combined with the first and second shock absorbers, this design structure allows the two shock absorption systems to be distributed at both ends of the wheel-legged position in the crouching, prone posture. The combination of the two systems also realizes the suspension system of the wheel-legged composite robot, which can further alleviate the bumps caused by road conditions in the wheel mode and protect the joints of the legs, thus producing a multiplied effect.

[0055] On the other hand, in order to improve the flexibility of steering the wheel 55 in the lower leg portion, in a preferred embodiment, the inventors considered achieving the rotational swing of the wheel 55 by using a design that mimics the rotation of the radial and ulnar wrist joint. Therefore, as follows... Figures 5-9 As shown, the wheel-foot unit 5 includes: a wheel 55, a drive motor 54, a wrist joint 56, a lower leg base 53, a linear actuator 57, a first rotary joint 58, and a second rotary joint 59. The drive motor 54 is fixed to the first side of the wrist joint 56, and its transmission end is connected to the wheel 55. The lower leg base 53 is connected to the pivot of the wrist joint 56. A rudder 561 extends outward from the second side of the wrist joint 56. A bracket 50 extends outward from the third end of the lower leg connecting rod 4, wherein the bracket 50 has the following shape... Figure 7 As shown, the example is roughly triangular in shape. The purpose of this design is to protect the linear actuator 57 on the inside from the outside, similar to how muscles are protected by bones, so as to achieve a protective effect.

[0056] Furthermore, the first end of the linear actuator 57 is hinged to the bracket 50 of the lower leg link 4 via the first rotary joint 58, and the second end is hinged to the rudder 561 via the second rotary joint 59. The second end of the lower leg link 4 is connected to the lower leg base 53.

[0057] Specifically, such as Figures 7-9 As shown, in order to simulate the pronation and supination movements of the human ulna and radius, the present invention ingeniously designs the lower leg base 53 to function as the ulna in a bionic mechanism, while the linear actuator 57 and the first and second rotary joints 59 act as the radius and its pronator and supinator muscles to connect with the lower leg link 4 and the wrist joint 56. Thus, by extending and retracting the linear actuator 57, the wrist joint 56 can be rotated to control the rotation angle of the wheel 55.

[0058] Therefore, in this example, the first rotary joint 58 includes: a first joint 581 and a second joint 582. The first joint 581 is Z-shaped, with a first longitudinal shaft fork on its first side and a second side fixed to the bracket 50. The second joint 582 is U-shaped, with a longitudinal shaft hole on its concave side and a transverse shaft hole near the fork head. The second joint 582 is connected to the first longitudinal shaft fork of the first joint 581 via the longitudinal shaft hole, and the fork head of the second joint 582 is connected to the first end shaft of the linear actuator 57 via the transverse shaft hole, so as to establish a hinge with two degrees of freedom between the linear actuator 57 and the lower leg connecting rod 4.

[0059] On the other hand, the second rotary joint 59 includes a third joint 591 and a fourth joint 592. The third joint 591 is U-shaped fork with a longitudinal shaft hole on its concave side and a transverse shaft hole near the fork head. The fourth joint 592 has a second longitudinal shaft fork and a third longitudinal shaft fork at its two ends, and the second longitudinal shaft fork and the third longitudinal shaft fork are inclined. The fourth joint 592 is connected to the longitudinal shaft hole of the third joint 591 via the second longitudinal shaft fork and is connected to the rudder stick 561 via the third longitudinal shaft fork. The third joint 591 is connected to the second end of the linear actuator 57 via the transverse shaft hole at the fork head, so as to establish a three-degree-of-freedom hinge between the linear actuator 57 and the rudder stick 561.

[0060] Thus, the biomimetic structure of the wrist joint can be realized through six mechanical components: the lower leg link 4, the linear actuator 57, the lower leg base 53, the wrist joint component 56, and the first and second rotary joint components 58 and 59. This allows the wrist joint component 56 to rotate relative to the lower leg base 53 under the drive of the linear actuator 57, mimicking the left and right swing of the wrist joint. This simulates the internal and external rotation of the radius and ulna in living organisms, supporting the rotation angle range of the wheel foot from -60 degrees to +60 degrees, thereby greatly improving the flexibility of the wheel foot leg structure.

[0061] On the other hand, the design structure of this wheel leg unit 5 allows the use of linear actuators 57 to simulate the functions of pronator and supinator muscles. Compared with existing solutions that require complex control algorithms, this solution can directly control the extension / contraction of linear actuators 57 to achieve and establish a control relationship with the wrist joint 56 for left and right rotation and swing. This makes operation more convenient and facilitates more precise motion control of the robot. Furthermore, since no motor is required in this structure, it also improves the miniaturization, lightweighting, and reliability of the wheel leg structure to a certain extent.

[0062] Furthermore, in order to detect the rotation angle of the wheel 55, the wrist joint 56 in this embodiment is provided with a first shaft hole and a keyway inside the first shaft hole, and the lower leg base 53 is provided with a second shaft hole. The lower leg base 53 and the wrist joint 56 are connected by a pivot shaft 562 inserted into the first and second shaft holes to form a rotating shaft connection. The pivot shaft 562 is provided with a flat key to engage with the keyway inside the first shaft hole of the wrist joint 56 to fix the axial position of the pivot shaft 562. An angle sensor 563 is provided on the top of the second shaft hole of the lower leg base 53. In this embodiment, a Hall angle sensor 563 is preferred, with its sensing area facing the top of the pivot shaft 562.

[0063] Therefore, when the linear actuator 57 extends or retracts, it can mimic the effect of the pronator and supinator muscles of the radius by working with the first and second rotary joints 58 and 59 to pull the rudder stick 561, causing the wrist joint 56 and the associated wheel 55 to rotate. At the same time, it will also cause the anti-loosening shaft 562 to rotate synchronously. Since the lower leg base 53 is fixed on the lower leg connecting rod 4, the relative position of the angle sensor 563 is fixed, so it can identify its rotation angle relative to the anti-loosening shaft 562, thereby detecting the rotation angle of the wheel 55, thus forming a closed-loop control.

[0064] It is worth mentioning that the design of the bionic wheel leg structure of this invention is conducive to establishing a control relationship between the sensing data and the extension distance of the linear actuator 57 to determine the rotation angle of the wheel 55. Compared with the prior art, due to the change in the mechanical transmission structure, the bionic structure of this solution can greatly simplify the complexity of the wheel 55 rotation angle control algorithm, thereby forming a control advantage.

[0065] Furthermore, in order to enhance the ability of the wrist joint 56 and the lower leg base 53 to withstand the axial force of the anti-loosening shaft 562, in a preferred embodiment, a bearing groove is provided at either the first shaft hole of the wrist joint 56 or the second shaft hole of the lower leg base 53 to accommodate the thrust bearing 564. The wrist joint 56 and the lower leg base 53 pass through the thrust bearing 564 via the anti-loosening shaft 562 and are inserted into the first and second shaft holes to form a rotating shaft connection.

[0066] Furthermore, to enable the detection of different terrains and obstacles, the front end of the wheel-legged composite robot body 1 can be equipped with a lidar 6 and a depth camera 7, while the rear end can be equipped with an ultrasonic radar 8, thereby supporting functions such as mapping and navigation, and autonomous obstacle avoidance. In this example, the wheel-legged body has four legs, including two front legs and two hind legs, with the front and hind legs having the same structure and arranged in a front elbow and hind knee configuration.

[0067] Therefore, the wheel-legged hybrid robot provided through the above examples can support wheeled motion mode, legged motion mode and wheel-legged hybrid motion mode.

[0068] For example, in wheeled motion mode, the joint motor assembly 2 is set to a fixed position mode to avoid unnecessary rotation. The robot moves by using the wheels 55 at the ends of its feet, and the steering motor 51 / linear actuator 57 above the wheels 55 controls the direction of the wheels 55. Combined with the existing four-wheel independent steering motion model, high-speed omnidirectional movement can be achieved on relatively flat surfaces.

[0069] For example, in the legged locomotion mode, the robot is considered a quadruped with three degrees of freedom for each leg. It adopts the walking gait of a quadruped robot, meaning that in each movement cycle, one leg is off the ground in the swing phase, while the remaining three legs are on the ground in the support phase. When a single leg is in the support phase, the support phase control algorithm of Virtual Model Control (VMC) is used to calculate the output torques of the joint motor group 2 based on the desired leg length, ensuring that the leg length remains constant. When a single leg is in the swing phase, the desired landing point is calculated based on the gait information. A swing curve connecting the starting point and the landing point is calculated using piecewise Bézier curves. Using the inverse kinematics equations of a three-degree-of-freedom single leg, the desired position and velocity of the three joints during the swing process are calculated based on the curve, allowing the foot to swing smoothly to the target position.

[0070] Furthermore, the tripod standing position during walking causes instability in robot 1. Therefore, the zero moment point method (ZMP) is used to calculate the current position of the zero moment point and ensure that it is within the support polygon to guarantee the robot's balance during legged movement.

[0071] For example, in the wheel-leg hybrid motion mode, the wheel 55 at the foot end is responsible for driving the robot's movement, while the leg joints are responsible for adapting to terrain changes and ensuring the balance of the robot body 1. This mode adopts single rigid body dynamics, that is, treating the robot body as a point mass and ignoring the mass of the four legs. An optimization function is established based on the single rigid body dynamics equation, and the desired state of the robot body and the feedback information of each joint are input into it. This is transformed into a convex optimization problem, and the three-dimensional contact force between the foot end and the ground is obtained by solving it. The obtained three-dimensional contact force is multiplied by the corresponding Jacobian of the leg to calculate the desired torque of each joint, so that the motion state of the robot body is controllable and stable movement is achieved in complex terrain.

[0072] Corresponding to the above-mentioned wheel-legged composite robot, such as Figures 10-12 As shown, the present invention also provides a passive sensing obstacle crossing method for controlling the wheel-legged hybrid robot of any of the above examples.

[0073] This design takes into account that when the robot's foot drive motor 54 is operating in a constant state, the internal current of the motor is a constant value. Therefore, by monitoring the changes in the current of the foot drive motor 54, the robot can detect whether its foot is touching the ground or leaving the ground, thereby enabling it to perceive the terrain and cross obstacles without prior detection.

[0074] Therefore, the steps of this passive obstacle-crossing method include:

[0075] In step S100, when the drive motor 54 of the sensing wheel foot unit 5 is obstructed, the current position P0 (x0, y0, z0) of the wheel 55 relative to the body 1 is recorded, and the drive motor 54 is stopped. For example, the current position of the wheel 55 relative to the body 1 is recorded first, and the speed of the foot drive motor 54 is set to 0, so that it stops rolling.

[0076] Step S200 starts at P0, causing the joint motor unit 2 to drive the crank four-bar linkage 3, the lower leg linkage 4, and the wheel and foot unit 5 to lift the leg upward in an arc trajectory until the wheel 55 contacts the obstacle, which is recorded as position P1 (x1, y1, z1). The approximate slope θ of the obstacle is calculated based on the position of the wheel 55.

[0077] ;

[0078] Step S300 plans the leg-lifting trajectory based on the slope θ, causing wheel 55 to move along the slope. This leg-lifting trajectory is a straight line with an angle of slope θ to the horizontal plane, ensuring that wheel 55 moves parallel to the slope. After detecting a foot-off-ground signal, steps S100 to S300 are repeated to re-estimate the obstacle slope and plan the leg-lifting trajectory, ensuring that wheel 55 remains close to the obstacle surface throughout the obstacle-crossing process. When the slope θ is detected to be close to 0°, the current position of wheel 55 is recorded as P. f (xf, yf, zf) Determine if wheel 55 is currently on top of an obstacle.

[0079] Step S400 At this time, according to P f By connecting P0, the geometric contour information of the obstacle can be obtained, that is, the height H and width L of the obstacle can be calculated, H = zf - z0, L = xf - x0. Based on these two pieces of information, the leg-lifting trajectory of the remaining wheel-foot unit 5 can be planned from P0 to P0. f Enable robots to overcome obstacles.

[0080] Furthermore, in a preferred embodiment, in step S300, when the wheel 55 moves along the slope with the leg raised, the drive motor 54 is activated to drive the wheel 55 to rotate at the same speed as the leg raising movement. This reduces the friction experienced by the wheel 55 during movement.

[0081] In summary, this invention provides a wheel-legged hybrid robot and its passive perception obstacle-crossing method, proposing a wheel-legged hybrid structure that rationally combines the advantages of wheeled and legged robots. It cleverly uses the joint motor assembly 2, the crank four-bar linkage 3, and the lower leg linkage 4 to mimic the hip and knee joint structures and power transmission of living organisms. This allows the robot's wheel-legged leg structure to freely switch between multiple modes, including upright walking, knee-bent prone, wheeled driving, and wheel-legged hybrid mode, selecting the most suitable movement mode according to the terrain. This achieves efficient flat-ground movement and obstacle-crossing capabilities in complex environments, truly possessing highly efficient all-terrain adaptability.

[0082] From the perspective of the design structure of the wheel-legged composite robot, this invention cleverly utilizes the technology that the wheel 55 drives the motor 54 to sense obstruction by sensing changes in current / voltage. Combined with the special wheel-leg structure of this invention, which enables the wheel 55 to cross obstacles, this invention passively senses terrain obstacles, thereby realizing the unique perception and obstacle-crossing functions of the wheel-legs. It is evident that compared to existing technologies that require mapping using LiDAR or visual analysis for obstacle perception and subsequent obstacle-crossing trajectory calculation, this implementation scheme is more ingenious and simpler, and has a lower implementation cost.

[0083] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The present invention is limited only by the claims and their full scope and equivalents. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

[0084] Those skilled in the art will understand that, besides implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0085] Furthermore, all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0086] Furthermore, various different implementations of the present invention can be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

1. A wheel-foot hybrid robot comprising: The body, joint motor group, crank four-bar linkage mechanism, shank connecting rod, wheel foot unit, wherein the crank four-bar linkage mechanism comprises: thigh connecting rod, thigh auxiliary connecting rod, drive connecting rod, knee joint connecting rod, the first end of the thigh connecting rod and the thigh auxiliary connecting rod is connected with the end motor stator of the joint motor group respectively, the drive connecting rod is connected with the end motor rotor of the joint motor group, the first end of the knee joint connecting rod is connected with the crank pivot of the drive connecting rod, the second end of the thigh connecting rod, the thigh auxiliary connecting rod and the knee joint connecting rod is pivotally connected with the first end of the shank connecting rod in the corresponding position, the wheel foot unit is connected with the second end of the shank connecting rod, the front end motor stator of the joint motor group is connected with the body; Wherein the joint motor group comprises: hip joint first motor, hip joint second motor, hip second mounting seat, hip first mounting seat, knee mounting seat, knee joint motor, the stator of the hip joint first motor is connected with the body through the hip first mounting seat, the transverse side of the hip second mounting seat is connected with the stator of the hip joint second motor, and the longitudinal side is connected with the rotor of the hip joint first motor, the stator of the knee joint motor is connected with the rotor of the hip joint second motor through the knee mounting seat, the first end of the thigh connecting rod and the thigh auxiliary connecting rod is connected with the stator of the knee joint motor respectively, the drive connecting rod is connected with the rotor of the knee joint motor; Wherein the joint motor group further comprises: first shock absorber, which comprises: mounting ring, support, first spring, wherein the spring is fixed on one side of the mounting ring through the support, and the first end of the thigh connecting rod is connected with the mounting ring, wherein the joint motor group drives the crank four-bar linkage mechanism to perform the action of bending knee and lying to about limit, and the first spring is abutted against the shank connecting rod; Wherein the second shock absorber comprises: support seat, second spring, wherein the second spring is connected at the first position of the body through the mounting seat, wherein the joint motor group drives the crank four-bar linkage mechanism to perform the action of bending knee and lying to about limit, and the second spring is abutted against the thigh connecting rod.

2. The wheel-legged hybrid robot of claim 1, wherein the wheel-legged unit comprises: Steering motor, mounting seat, shank base, drive motor, wheel, wherein the drive motor transmission end is connected with the wheel, the transverse side of the mounting seat is connected with the drive motor, and the longitudinal side is connected with the transmission end of the steering motor, the steering motor is connected with the second end of the shank connecting rod through the shank base.

3. The wheel-legged hybrid robot of claim 1, wherein the wheel-legged unit comprises: Wheel, drive motor, wrist joint part, shank base, linear drive, first rotary joint part, second rotary joint part, wherein the drive motor is fixed on the first side of the wrist joint part, the drive motor transmission end is connected with the wheel, the shank base is pivotally connected with the wrist joint part, the second side of the wrist joint part extends outward to a rudder rod, wherein the third end of the shank connecting rod extends outward to a support, the first end of the linear drive is hingedly connected with the shank connecting rod support through the first rotary joint part, and the second end is hingedly connected with the rudder rod through the second rotary joint part, the second end of the shank connecting rod is connected with the shank base.

4. The wheel-legged hybrid robot of claim 3, wherein the first revolute joint comprises: The first joint is Z-shaped, with a first longitudinal shaft fork on one side and a second side fixed on the bracket. The second joint is U-shaped fork, with a longitudinal shaft hole on one side and a transverse shaft hole near the fork head. The second joint is connected with the first longitudinal shaft fork of the first joint through the longitudinal shaft hole, and the fork head of the second joint is connected with the first end of the linear driver through the transverse shaft hole, so as to establish two degrees of freedom between the linear driver and the shank connecting rod.

5. The wheel-legged hybrid robot of claim 3, wherein the second revolute joint comprises: The third joint is U-shaped fork, with a longitudinal shaft hole on one side and a transverse shaft hole near the fork head. The fourth joint is provided with a second longitudinal shaft fork and a third longitudinal shaft fork at two ends, and the second longitudinal shaft fork is inclined to the third longitudinal shaft fork. The fourth joint is connected with the longitudinal shaft hole of the third joint through the second longitudinal shaft fork, and is connected with the rudder through the third longitudinal shaft fork. The third joint is connected with the second end of the linear driver through the transverse shaft hole of the fork head, so as to establish three degrees of freedom between the linear driver and the rudder.

6. A passive obstacle sensing method for controlling the wheel-foot hybrid robot according to any one of claims 1 to 5, comprising the following steps: Step S100: when the driving motor of the wheel-foot unit is blocked, record the current position P0 (x0, y0, z0) of the wheel relative to the body, and stop the driving motor; Step S200: take P0 as the starting point, and drive the crank four-bar linkage mechanism, the shank connecting rod and the wheel-foot unit to move upward along an arc trajectory until the wheel contacts the obstacle at position P1 (x1, y1, z1), and calculate the approximate slope θ of the obstacle according to the positions before and after the wheel. ； Step S300 plans a leg-lifting trajectory according to the slope θ, makes the wheel move along the slope to lift the leg, and repeats steps S100-S300 until the sensed slope θ is close to 0°, and records the current wheel position as P f (xf, yf, zf); Step S400 calculates the obstacle height H and width L according to P f The obstacle height H and width L are calculated according to P0, H = zf - z0, L = xf - x0, so as to plan the rest of the wheel-foot unit leg-lifting trajectory from P0 swing to P f .

7. The passive obstacle sensing method according to claim 6, wherein in step S300, when the wheel moves upward along the slope, the driving motor is started to drive the wheel to rotate at a speed equivalent to the moving speed of the upward movement.

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