A wheel-legged robot

Abstract

The application discloses a wheel-legged robot, which can realize front and back swing and inner and outer swing of a leg structure, and has the ability of unfolding or folding, so as to realize various leg actions such as forward crossing, forward moving, side crossing, side moving, turning, wheel moving and high-speed advancing, and has comprehensive functions and wide adaptability to various terrain conditions such as flat ground, multi-obstacle ground, single step, continuous steps, single-side slope ground and the like. The main structure of the application comprises a main machine, a power source, a pair of unfolding and folding wheel leg assemblies and two rotation degree of freedom limiting assemblies. The unfolding and folding wheel leg assembly comprises a four-bar linkage mechanism, a leg unfolding and folding joint and a driving wheel assembly. The rotation degree of freedom limiting assembly comprises a front and back swing joint for driving the front and back swing of the leg unfolding and folding joint and an inner and outer swing joint for driving the inner and outer swing of the front and back swing joint. When the front and back swing joint swings inwards, the driving wheel assembly is close to a vertical symmetry plane, and when the front and back swing joint swings outwards, the driving wheel assembly is away from the vertical symmetry plane.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, and particularly relates to a wheeled-legged robot. Background Technology

[0002] Currently, common ground robots can be broadly categorized into legged robots and wheeled robots. Wheeled robots are energy-efficient, fast-moving, stable, and simple in structure, but they are only suitable for flat terrain with good surfaces and are greatly affected by terrain; they cannot overcome obstacles of a certain height. Legged robots, on the other hand, have strong obstacle-crossing capabilities, can adapt to various terrains, and are highly flexible and adaptable. However, legged robots are slow, have complex structures, and lower energy efficiency. In recent years, wheeled-legged robots have emerged, combining these two types of robots. They not only possess superior terrain adaptability but also significantly improve the robot's endurance.

[0003] However, most existing wheeled robot solutions use the method of placing the drive wheels at the ends of the legs, which still has certain drawbacks: the large size of the drive wheels increases the volume of the mechanism at the end of the legs, which to some extent affects its adaptability to terrain; on the other hand, the use of two parallel legs locks the distance between the legs in the direction of travel (the distance between the two drive wheels), which also limits its flexibility. Summary of the Invention

[0004] This invention provides a wheel-legged robot with a rotational degree-of-freedom limiting component, which can realize the forward and backward swinging and inward and outward swinging of the leg structure. Since the leg structure itself has the ability to unfold or retract, it can realize various leg movements such as forward stride, forward movement, side stride, side movement, turning, and wheel-driven rapid advance. It has comprehensive functions and is suitable for various terrain conditions such as flat ground, multi-obstacle ground, single steps, continuous steps, and single-sided slopes, with wide adaptability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A wheeled-legged robot includes a main unit, a power source, and a pair of extendable and retractable wheel leg assemblies disposed on both sides of the main unit, and also includes two rotational degree-of-freedom limiting components;

[0007] The retractable wheel assembly includes a four-bar linkage, a leg retractable joint for driving the four-bar linkage to extend or retract, and a drive wheel assembly located at the end of the four-bar linkage. The retractable wheel assembly corresponds one-to-one with the rotational degree-of-freedom limiting assembly.

[0008] The pair of retractable wheel leg assemblies are arranged symmetrically along a vertical symmetry plane, the front-rear direction of the main unit is parallel to the vertical symmetry plane, and the forward direction of the drive wheel assembly is parallel to the vertical symmetry plane.

[0009] In the corresponding extension and retraction wheel leg assembly and rotational degree of freedom limiting assembly: the rotational degree of freedom limiting assembly includes a forward and backward swing joint for driving the leg extension and retraction joint to swing back and forth, and an inward and outward swing joint for driving the forward and backward swing joint to swing inward and outward. When the forward and backward swing joint swings inward, the drive wheel assembly moves closer to the vertical plane of symmetry. When the forward and backward swing joint swings outward, the drive wheel assembly moves away from the vertical plane of symmetry.

[0010] Preferably, the four-bar linkage includes a first link, a second link, a third link, and a fourth link. In an extendable / retractable leg assembly: the leg extendable / retractable joint includes a leg joint body and an extendable / retractable drive shaft that can rotate relative to the leg joint body. The first link is connected to the leg joint body, one end of the second link is connected to the extendable / retractable drive shaft, the other end of the second link is hinged to one end of the fourth link, one end of the third link is hinged to the first link, and the other end of the third link is hinged to the middle of the fourth link.

[0011] Preferably, a rear torsion spring is provided at the hinge joint between the second link and the fourth link, one end of the rear torsion spring is connected to the second link, and the other end of the rear torsion spring is connected to the fourth link. A front torsion spring is provided at the hinge joint between the third link and the fourth link, one end of the front torsion spring is connected to the third link, and the other end of the front torsion spring is connected to the fourth link.

[0012] When the four-bar linkage is retracted to its ultimate retracted position, the rear torsion spring is twisted and stores energy, and the front torsion spring is twisted and stores energy.

[0013] Preferably, in the corresponding extension and retraction wheel leg assembly and rotational degree of freedom limiting assembly: when the front and rear swing joint drives the leg extension and retraction joint to swing back and forth, the rotation center line of the leg extension and retraction joint coincides with the rotation center line of the extension and retraction drive shaft; when the inward and outward swing joint drives the front and rear swing joint to swing inward and outward, the rotation center line of the front and rear swing joint is parallel to the front and rear direction of the main unit.

[0014] Preferably, the drive wheel assembly includes a drive wheel body disposed at the other end of the fourth link and a hub motor disposed on the drive wheel body, the hub motor being used to drive the drive wheel body to rotate.

[0015] Preferably, the hub motor includes a fixed housing, a rotating housing, a motor stator, a motor rotor, and a motor drive plate. In a drive wheel assembly: the fixed housing is fixed to the drive wheel body, the motor stator is fixed on the fixed housing, the motor rotor includes a rotor shaft and a rotor body connected to the rotor shaft, the rotor body is sleeved outside the motor stator, the motor stator has an internal space, and the motor drive plate is located within the internal space.

[0016] Preferably, the system also includes a sensing module. The power source includes a power battery. The sensing module, the rotational degree-of-freedom limiting component, and the power battery are arranged sequentially along the front-rear direction of the main unit. The power battery is detachably connected to the rear side of the main unit, the sensing module is located on the front side of the main unit, and the leg joint body and the rotational degree-of-freedom limiting component are located below the main unit.

[0017] Preferably, the vertical projection of the forward and backward swing joint overlaps with the vertical projection of the main unit, and the vertical projection of the inward and outward swing joints overlaps with the vertical projection of the main unit. The extension and retraction wheel leg assembly is connected to the forward and backward swing joints via a lateral connector. The lateral connector includes a first connector and a second connector. The first connector is fixed to the second connector by a plurality of lateral bolts. The vertical projection of the lateral bolts is outside the vertical projection range of the main unit. When the forward and backward swing joints drive the extension and retraction joints to swing forward and backward, the angle between the rotation center line of the extension and retraction joints and the axis of any lateral bolt is M degrees, where M is greater than or equal to 45 degrees and M is less than or equal to 90 degrees.

[0018] The first connector is connected to the forward and backward swing joint, and the second connector is connected to the leg extension and retraction joint.

[0019] Preferably, the main unit is provided with a front support wheel assembly and a rear support wheel assembly. When all four-bar linkages are in their extreme retracted positions, the lowest point of the front support wheel assembly, the lowest point of the drive wheel, and the lowest point of the rear support wheel assembly are all in the same plane.

[0020] The front support wheel assembly includes two front swivel wheels, and the rear support wheel assembly includes two rear swivel wheels.

[0021] Preferably, the retractable wheel assembly further includes a locking component, which includes a first locking structure and a second locking structure that can be locked and fixed with the first locking structure. In a retractable wheel assembly, both the first locking structure and the second locking structure are disposed on a four-bar linkage. When the first locking structure and the second locking structure are locked and fixed, the four-bar linkage remains in the extreme retracted position.

[0022] The beneficial effects of this invention are as follows: It has a rotational degree-of-freedom limiting component, which can realize the forward and backward swinging and inward and outward swinging of the leg structure. Since the leg structure itself has the ability to extend or retract, it can realize various leg movements such as forward stride, forward movement, side stride, side movement, turning, and wheel-driven rapid advance. It is comprehensive in function and applicable to various terrain conditions such as flat ground, multi-obstacle ground, single steps, continuous steps, and single-sided slopes, with wide adaptability. It has a torsion spring structure. When the four-bar linkage is extended, the height of the main unit needs to be raised at the same time. The elastic potential energy of the torsion spring structure can help the four-bar linkage to extend, making the action feedback faster and more agile. The positions of each structure are reasonably arranged, and the overall layout and counterweight are reasonable. The extension and retraction wheel leg assembly and the forward and backward swinging joint are installed through structures such as lateral bolts, with less interference and convenient assembly and disassembly. It has a structure that can lock the four-bar linkage under certain conditions, which can reduce energy consumption accordingly. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention;

[0024] Figure 2 This is the front view of the present invention;

[0025] Figure 3 This is a side view of the present invention;

[0026] Figure 4 This is a bottom view of the present invention;

[0027] Figure 5 This is a partial structural schematic diagram of Embodiment 1 of the present invention;

[0028] Figure 6 This is a schematic diagram of the structure of the hub motor in this invention;

[0029] Figure 7 This is an exploded view of a portion of the hub motor structure of the present invention;

[0030] Figure 8 This is a schematic diagram of the structure at the lateral connector of the present invention;

[0031] Figure 9 This is a schematic diagram of the structure of the four-bar linkage of the present invention when it is retracted to the extreme retracted position;

[0032] Figure 10 This is a partial structural diagram of the rear universal wheel in Embodiment 2 of the present invention;

[0033] Figure 11 This is a partial structural diagram of the front universal wheel in Embodiment 2 of the present invention.

[0034] Reference numerals: 1. Main unit; 101. Front caster wheel; 102. Rear caster wheel; 2. Power source; 201. Rear torsion spring; 202. Front torsion spring; 203. Drive wheel; 3. Rotational freedom limiting component; 301. Forward and backward swing joint; 302. Inward and outward swing joint; 4. Four-bar linkage; 401. First link; 402. Second link; 402.1. Locking pin mechanism; 403. Third link; 404. Fourth link; 5. Leg extension and retraction joint; 501. Lateral connector; 501.1. First connecting piece; 501.2. Second connecting piece; 502. Lateral bolt; 6. Hub motor; 601. Fixed housing; 602. Rotating housing; 60 3. Motor stator; 604. Motor rotor; 604.1. Rotor shaft; 604.2. Rotor body; 604.2. Motor drive board; 605. Induction module; 7. Cylinder body; 801.1. Upper negative pressure chamber; 801.2. Lower normal pressure chamber; 801a. Normal pressure connecting hole; 801b. Buffer exhaust hole; 802. Cylinder piston; 803. Cylinder piston rod; 804. Limiting body; 805. Pressurized air pipe; 806. Vertical sliding rod; 807. Slide seat; 808. Lower top spring; 901. First fixed contact; 902. First moving contact; 903. Second fixed contact; 904. Second moving contact. Detailed Implementation

[0035] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1:

[0037] like Figures 1 to 4 As shown, a wheeled-legged robot includes a main unit 1, a power source 2, and a pair of extendable and retractable wheel leg assemblies disposed on both sides of the main unit 1, and also includes two rotational degree-of-freedom limiting components 3;

[0038] The retractable wheel assembly includes a four-bar linkage 4, a leg retractable joint 5 for driving the four-bar linkage 4 to unfold or retract, and a drive wheel assembly located at the end of the four-bar linkage 4. The retractable wheel assembly corresponds one-to-one with the rotational degree of freedom limiting assembly 3.

[0039] The pair of retractable wheel leg assemblies are arranged symmetrically along a vertical symmetry plane. The front-to-back direction of the main unit 1 is parallel to the vertical symmetry plane, and the forward direction of the drive wheel assembly is parallel to the vertical symmetry plane.

[0040] In the corresponding extension and retraction wheel assembly and rotational degree-of-freedom limiting assembly 3: the rotational degree-of-freedom limiting assembly 3 includes a forward and backward swing joint 301 for driving the extension and retraction joint 5 of the leg to swing back and forth, and an inward and outward swing joint 302 for driving the forward and backward swing joint 301 to swing inward and outward. When the inward and outward swing joint 302 drives the forward and backward swing joint 301 to swing inward, the drive wheel assembly approaches the vertical symmetry plane. When the inward and outward swing joint 302 drives the forward and backward swing joint 301 to swing outward, the drive wheel assembly moves away from the vertical symmetry plane.

[0041] The technical solution of this invention uses an extendable / retractable leg assembly as the leg structure of the robot. It includes a four-bar linkage 4, a leg extendable / retractable joint 5, and a drive wheel assembly. The extension or retraction of the four-bar linkage 4 allows the height of the main unit 1 to rise or fall. Based on this, the rotational degree-of-freedom limiting assembly 3 includes a forward / backward swing joint 301 and an inward / outward swing joint 302, which constitute two rotational degrees of freedom, allowing the leg structure to rotate forward / backward (swing) and rotate inward / outward (swing) as a whole. The leg extendable / retractable joint 5, the forward / backward swing joint 301, and the inward / outward swing joint 302 can all be motors.

[0042] The leg structure can rotate forward and backward as a whole. With the expansion and contraction of the four-bar linkage 4, the leg structure can step forward (backward). The two leg structures can step forward (backward) in turn to achieve overall forward (backward) movement or continuous obstacle crossing. As long as the "leg height" when stepping forward (backward) is sufficient, it can step onto the steps (both single steps and continuous steps).

[0043] The leg structure can rotate inward and outward as a whole. With the expansion and contraction of the four-bar linkage 4, the leg structure can be used to step sideways. The two leg structures can step sideways in one direction in turn to achieve overall lateral movement or continuous obstacle crossing. As long as the "leg lift height" is sufficient when stepping sideways, it can step sideways onto the steps (both single steps and continuous steps are possible).

[0044] When the present invention is used on flat ground, the four-bar linkage 4 retracts to its maximum retracted position, such as... Figure 9As shown, the height of the main unit 1 is lowered to its minimum, thus lowering the overall center of gravity. At this time, the drive wheel assembly operates, allowing the invention to move quickly, i.e., entering the wheel-driven rapid-movement mode (lower overall center of gravity ensures greater stability during rapid movement). When turning is required, the two drive wheel assemblies operate differentially. When traversing a single-sided slope, one leg structure is tilted outwards, and the drive wheel assembly on that tilted leg structure contacts the slope, while the other drive wheel assembly remains on flat ground. With the drive wheel assembly operating, the invention can move quickly forward on a single-sided slope. Furthermore, when making rapid turns on flat ground, the outer leg structure can be tilted outwards (the side furthest from the turning center is the outer side), thereby adjusting the overall center of gravity and improving stability during rapid cornering, i.e., "cornering pressure."

[0045] like Figures 1 to 4 As shown, the four-bar linkage 4 includes a first link 401, a second link 402, a third link 403, and a fourth link 404. In an extension and retraction wheel leg assembly: the leg extension and retraction joint 5 includes a leg joint body and an extension and retraction drive shaft that can rotate relative to the leg joint body. The first link 401 is connected to the leg joint body. One end of the second link 402 is connected to the extension and retraction drive shaft, and the other end of the second link 402 is hinged to one end of the fourth link 404. One end of the third link 403 is hinged to the first link 401, and the other end of the third link 403 is hinged to the middle of the fourth link 404.

[0046] like Figure 5 As shown, a rear torsion spring 201 is provided at the hinge joint between the second link 402 and the fourth link 404. One end of the rear torsion spring 201 is connected to the second link 402, and the other end of the rear torsion spring 201 is connected to the fourth link 404. A front torsion spring 202 is provided at the hinge joint between the third link 403 and the fourth link 404. One end of the front torsion spring 202 is connected to the third link 403, and the other end of the front torsion spring 202 is connected to the fourth link 404.

[0047] When the four-bar linkage 4 is retracted to its ultimate retracted position, the rear torsion spring 201 is twisted and stores energy, and the front torsion spring 202 is twisted and stores energy.

[0048] like Figure 3 , Figure 5As shown, when the fourth link 404 is perpendicular (or nearly perpendicular) to the second link 402 and perpendicular (or nearly perpendicular) to the third link 403, the rear torsion spring 201 and the front torsion spring 202 are in an untorsed state. During the unfolding or retracting of the four-bar linkage 4, the torsion springs will be torsioned as the angle between the fourth link 404 and the second and third links 402 changes. Specifically, when the four-bar linkage 4 unfolds, the height of the main unit 1 needs to be raised simultaneously. The weight of the main unit 1 and its components increases resistance. At this time, the elastic potential energy of the front torsion spring 202 and the rear torsion spring 201 can be used to assist the four-bar linkage 4 in unfolding, making the action feedback faster and more agile.

[0049] like Figures 1 to 4 As shown, in the corresponding extension and retraction wheel leg assembly and rotational degree of freedom limiting assembly 3: when the front and rear swing joint 301 drives the leg extension and retraction joint 5 to swing back and forth, the rotation center line of the leg extension and retraction joint 5 coincides with the rotation center line of the extension and retraction drive shaft; when the inward and outward swing joint 302 drives the front and rear swing joint 301 to swing inward and outward, the rotation center line of the front and rear swing joint 301 is parallel to the front and rear direction of the main unit 1.

[0050] like Figure 1 , Figure 6 As shown, the drive wheel assembly includes a drive wheel body 203 disposed at the other end of the fourth link 404 and a hub motor 6 disposed on the drive wheel body 203. The hub motor 6 is used to drive the drive wheel body 203 to rotate. By driving the drive wheel body 203 with the hub motor 6, "wheel-driven rapid advance" can be achieved, that is, the drive wheel body 203 rotates and the whole body moves forward quickly. The hub motor 6 can be regarded as a structure integrated on the drive wheel body 203, effectively saving space near the host 1. Since the space near the host 1 is very tight, it may be necessary to arrange various structures such as the power source 2, the sensing module 7, the leg extension and retraction joint 5, the front and rear swing joint 301, the inward and outward swing joint 302, the connection structure between the joints, various data cables, and the controller. Therefore, for the space near the host 1, "rational layout" and "saving space wherever possible" are major priorities. In this solution, the use of the hub motor 6 conforms to the principle of "saving space wherever possible", thus laying the foundation for the rationality of the overall layout of the present invention.

[0051] like Figure 6 , Figure 7As shown, the hub motor 6 includes a fixed housing 601, a rotating housing 602, a motor stator 603, a motor rotor 604, and a motor drive plate 605. In a drive wheel assembly: the fixed housing 601 is fixed to the drive wheel body 203, the motor stator 603 is fixed on the fixed housing 601, the motor rotor 604 includes a rotor shaft 604.1 and a rotor body 604.2 connected to the rotor shaft 604.1, the rotor body 604.2 is sleeved outside the motor stator 603, the motor stator 603 has an internal space, and the motor drive plate 605 is located within the internal space.

[0052] The motor drive board 605 (i.e., the circuit board and chip structure used to control the motor) is an important component for controlling the hub motor 6. In traditional hub motors 6, the motor drive board 605 is external, which requires the use of space near the host 1. In this solution, the stator is built-in and the rotor is external (the rotor body 604.2 is sleeved outside the motor stator 603), which frees up some space inside the stator (i.e., the space inside the stator) to accommodate the motor drive board 605. Thus, the motor drive board 605 does not have to occupy the space near the host 1, which also makes an effective contribution to the rationality of the overall layout of the present invention.

[0053] like Figures 1 to 4 As shown, it also includes a sensing module 7. The power source 2 includes a power battery. The sensing module 7, the rotational degree of freedom limiting component 3 and the power battery are arranged sequentially along the front and rear direction of the host 1. The power battery is detachably connected to the rear side of the host 1. The sensing module 7 is located on the front side of the host 1. The leg joint body and the rotational degree of freedom limiting component 3 are located below the host 1.

[0054] The power battery and sensing module 7 are relatively heavy, and they are positioned separately at the front and rear of the main unit 1. The space below the main unit 1 is used to house part or all of the leg joint body and part or all of the degree-of-freedom limiting components. In this way, the main unit 1 has structures at the front, middle, and rear, with a relatively reasonable weight distribution. It also makes good use of the limited space to achieve a reasonable overall layout, resulting in better overall balance during operation. In addition, the power battery is removable, thus facilitating charging and other operations.

[0055] like Figure 4 , Figure 8As shown, the vertical projection of the front-to-back swing joint 301 overlaps with the vertical projection of the host 1, and the vertical projection of the inner-outer swing joint 302 overlaps with the vertical projection of the host 1. The extension and retraction wheel leg assembly is connected to the front-to-back swing joint 301 via a lateral connector 501. The lateral connector 501 includes a first connector 501.1 and a second connector 501.2. The first connector 501.1 is fixed to the second connector 501.2 by a plurality of lateral bolts 502. The vertical projection of the lateral bolts 502 is outside the vertical projection range of the host 1. When the front-to-back swing joint 301 drives the leg extension and retraction joint 5 to swing back and forth, the angle between the rotation center line of the leg extension and retraction joint 5 and the axis of any lateral bolt 502 is M degrees, where M is greater than or equal to 45° and M is less than or equal to 90°.

[0056] The first connector 501.1 is connected to the forward and backward swing joint 301 and the second connector 501.2 is connected to the leg extension and retraction joint 5. The first connector 501.1 is sleeved on the second connector 501.2.

[0057] As mentioned earlier, due to the limited space near the main unit 1, it may be necessary to arrange various structures such as the power source 2, sensing module 7, leg extension and retraction joint 5, front and rear swing joint 301, inner and outer swing joint 302, connection structures between the joints, various data cables, and controllers. Therefore, for the space near the main unit 1, "rational layout" and "saving as much as possible" are also major priorities. Obviously, a connection structure is needed between the extension and retraction wheel leg assembly and the front and rear swing joint 301. The connection structure of "side bolt 502 fixing" adopted in this solution has two major advantages: First, the vertical projection of the side bolt 502 is outside the vertical projection range of the main unit 1, so there is no need to disassemble the machine locally or move other structures. The assembly, disassembly, and maintenance of the extension and retraction wheel leg assembly and the front and rear swing joint 301 can be carried out directly (i.e., the side bolt 502 can be rotated). Otherwise, if a flange connection and axial bolt fixing (with the bolt axis parallel or nearly parallel to the axis of the drive wheel 203) are used for transmission, the bolts will be obstructed (interfered) by the inner and outer swing joints 302, the four-bar linkage 4, and another extension and retraction wheel assembly. This will cause the disassembly and assembly of the extension and retraction wheel assembly and the front and rear swing joints 301 to require the disassembly of other structures first, which will greatly increase the complexity of installation and maintenance.

[0058] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 9As shown, the host 1 is provided with a front support wheel set and a rear support wheel set. When all four-bar linkages 4 are in the extreme retracted position, the lowest point of the front support wheel set, the lowest point of the drive wheel 203 and the lowest point of the rear support wheel set are all in the same plane.

[0059] The front support wheel assembly includes two front swivel wheels 101, and the rear support wheel assembly includes two rear swivel wheels 102.

[0060] When the present invention is on flat ground, if the four-bar linkage 4 is in its maximum retracted position and the drive wheel 203 is in contact with the ground, then both the front swivel wheel 101 and the rear swivel wheel 102 are in contact with the ground. At this time, the front swivel wheel 101 and the rear swivel wheel 102 participate in supporting the weight of the main unit 1 and other structures. The drive wheel assembly provides driving force on both sides, and steering and other operations are achieved through differential control of the drive wheel assemblies on both sides, so as to realize high-speed movement (wheel-driven rapid advance) mode on flat ground. When it is necessary to cross higher steps, the front support wheel assembly can serve as auxiliary support.

[0061] The retractable wheel assembly also includes a locking assembly, which includes a first locking structure and a second locking structure that can be locked and fixed with the first locking structure. In a retractable wheel assembly, both the first locking structure and the second locking structure are mounted on a four-bar linkage 4. When the first locking structure and the second locking structure are locked and fixed, the four-bar linkage 4 remains in the extreme retracted position.

[0062] When the height of the invention is reduced and the drive components are used for rapid movement, if the ground is not perfectly flat, the four-bar linkage 4 will inevitably move continuously due to shaking and vibration. This requires the leg extension and retraction joint 5 and the forward and backward swing joint 301 to be constantly adjusted. In this solution, after locking the four-bar linkage 4, only the forward and backward swing joint 301 needs to be adjusted, and the leg extension and retraction joint 5 does not work, making the whole system more energy-efficient.

[0063] like Figure 3 As shown, in an extension / retraction wheel assembly: the first locking structure is a locking pin mechanism 402.18 located in the middle of the second link 402, and the second locking structure is a locking hole located on the fourth link 404. The locking hole is adapted to the locking pin mechanism 402.18. When the four-bar linkage 4 is in its ultimate retracted position, the locking pin mechanism 402.18 and the locking hole can lock together. The locking pin mechanism 402.18 can be an electromagnetic locking pin.

[0064] Example 2:

[0065] Based on Example 1, such as Figure 10 , Figure 11As shown, it also includes a terrain change protection system, which includes a pressure-storing airbag, two pressure-replenishing buffer structures and a conversion circuit. The pressure-storing airbag is located in front of the sensing module 7. The pressure-storing airbag is equipped with a pressure valve and a pressure supply port. When encountering an unavoidable obstacle in front, the pressure-storing airbag will contact the obstacle in front of the host 1 first. The buffer structure includes a vertically arranged cylinder body 801, a cylinder piston 802 that slides and seals with the cylinder body 801, and a cylinder piston rod 803 located on the cylinder piston 802.

[0066] In a pressure-compensating buffer structure: the piston 802 inside the cylinder divides the interior of the cylinder body 801 into an upper negative pressure chamber 801.1 and a lower normal pressure chamber 801.2. The air pressure in the upper negative pressure chamber 801.1 is lower than one standard atmosphere. In practical applications, the air pressure in the upper negative pressure chamber 801.1 should preferably be 0.1 to 0.6 atmospheres. This can better "hold" the piston inside the cylinder, preventing it from easily falling. The upper negative pressure chamber 801.1 is equipped with a limiter for the piston inside the cylinder. The piston 802 has a limiting body 804. The cylinder piston rod 803 passes through the lower atmospheric pressure chamber 801.2. The upper end of the cylinder piston rod 803 is connected to the piston 802 inside the cylinder. The bottom of the cylinder body 801 is provided with an atmospheric pressure communication hole 801a. The side wall of the cylinder body 801 is provided with a buffer exhaust hole 801b communicating with the lower atmospheric pressure chamber 801.2 and an air extraction valve communicating with the upper negative pressure chamber 801.1. The upper negative pressure chamber 801.1 is connected to the pressure supply port through a pressure supply pipe 805.

[0067] The front support wheel assembly is mounted on the main unit 1 through a wheel assembly connection structure, and the rear support wheel assembly is mounted on the main unit 1 through another wheel assembly connection structure. The wheel assembly connection structure corresponds one-to-one with the pressure-compensating buffer structure. In the corresponding wheel assembly connection structure and pressure-compensating buffer structure: the wheel assembly connection structure includes a vertical slide rod 806, a slide seat 807 connected to the lower end of the cylinder piston rod 803, a slide groove opening at the bottom of the slide seat 807, and a lower push spring 808 provided in the slide groove. The upper end of the vertical slide rod 806 is located in the slide groove, and the vertical slide rod 806 is slidably connected to the slide groove. The slide groove, the lower push spring 808, and the upper end of the vertical slide rod 806 are connected sequentially from top to bottom.

[0068] The switching circuit includes a first fixed contact 901, a first movable contact 902 that can contact the first fixed contact 901, a second fixed contact 903, a second movable contact 904 that can contact the second fixed contact 903, a third movable contact, a third movable contact that can contact the third fixed contact, and a solenoid valve. The first movable contact 902 corresponds to one wheel assembly connection structure and is connected to the vertical slide rod 806 in the corresponding wheel assembly connection structure. The second movable contact 904 corresponds to another wheel assembly connection structure and is connected to the vertical slide rod 806 in the corresponding wheel assembly connection structure. The vertical sliding rod 806 in the wheel assembly connection structure is connected. The third moving contact is set on the main unit 1, the third fixed contact is set on the fourth connecting rod 404, and the solenoid valve is set at the pressure supply port. When the four-bar linkage 4 is in the extreme retracted position, if the present invention is on flat ground and the drive wheel 203 is in contact with the ground, then the front universal wheel 101 and the rear universal wheel 102 are both in contact with the ground. The first moving contact 902 is separated from the first fixed contact 901, the second moving contact 904 is separated from the second fixed contact 903, and the third fixed contact is in contact with the third moving contact.

[0069] The power source 2 is connected in series in the conversion circuit, and the power source 2 supplies power to the conversion circuit. The solenoid valve is normally open when energized and normally closed when de-energized. The first fixed contact 901 is located below the first moving contact 902, and the second fixed contact 903 is located below the second moving contact 904. When the first moving contact 902 is in contact with the first fixed contact 901, the second moving contact 904 is in contact with the second fixed contact 903, and the third moving contact is in contact with the third fixed contact, the power source 2, the first moving contact 902, the first fixed contact 901, the second moving contact 904, the second fixed contact 903, the third moving contact, the third fixed contact, and the solenoid valve are connected in series in sequence, and the conversion circuit is energized.

[0070] In this embodiment, the pressure-storing airbag can be filled with gas through a pressure valve. The air pressure in the pressure-storing airbag is relatively high (not less than one standard atmosphere). Since the pressure-storing airbag is located in front of the sensing module 7, and the sensing module 7 is in the foremost position (except for the pressure-storing airbag), when the present invention is about to collide with an obstacle in front due to various factors, the pressure-storing airbag will contact the obstacle in front of the main unit 1 first, thereby effectively playing a buffering role and protecting the valuable structures such as sensors, power source 2, and joints on the main unit 1.

[0071] When the drive wheel assembly moves forward rapidly, if a significant drop suddenly occurs in the ground ahead (such as a large pit or a steeply descending step), and the invention fails to decelerate and stop in time, the entire invention will fall a considerable height. Since the four-bar linkage 4 is in its most retracted position (with virtually no cushioning), this can easily lead to damage to valuable structures on the main unit 1, such as sensors, power source 2, and joints, due to the large impact. In this solution, when the four-bar linkage 4 is not in its most retracted position, the third moving contact separates from the third fixed contact, the switching circuit is disconnected, and the solenoid valve is de-energized and normally closed. When the invention moves forward at high speed, the third fixed contact contacts the third moving contact, both the front omnidirectional wheel 101 and the rear omnidirectional wheel 102 contact the ground, the first moving contact 902 separates from the first fixed contact 901, and the second moving contact 904 separates from the second fixed contact 903. The switching circuit is disconnected, and the solenoid valve is de-energized and normally closed. When a significant drop suddenly occurs in the ground ahead and the invention fails to decelerate or stop in time, the invention will fall a considerable height. During this process, all front casters 101 and rear casters 102 will move downwards. That is, under the action of the lower spring 808, the vertical slide rod 806 will move slightly downwards. Thus, when the first moving contact 902 contacts the first fixed contact 901, the second moving contact 904 contacts the second fixed contact 903, and the third fixed contact is already in contact with the third moving contact, the switching circuit is energized, the solenoid valve is energized and normally open, and a portion of the gas in the pressure bladder enters the upper negative pressure chamber 801.1 through the pressure supply port and pressure supply pipe 805. The piston 802 and vertical slide rod 806 in the cylinder move downwards, and the piston 802 in the cylinder moves downwards. 2. Move to a position below the buffer vent 801b (a portion of the gas in the upper negative pressure chamber 801.1 is discharged through the buffer vent 801b, but this does not affect the increase in gas and pressure in the upper negative pressure chamber 801.1 in a short time). The lower end of the front universal wheel 101 is lower than the drive wheel assembly, and the lower end of the rear universal wheel 102 is lower than the drive wheel assembly. If the invention is then landed, the front universal wheel 101 and the rear universal wheel 102 will touch the ground first. Then, the gas in the upper negative pressure chamber 801.1 can buffer the overall impact. A portion of the gas in the upper negative pressure chamber 801.1 is quickly discharged through the buffer vent 801b, which buffers the impact and protects the valuable structures such as sensors, power source 2, and joints on the main unit 1.

[0072] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A wheel-legged robot, characterized in that, It includes a main unit (1), a power source (2) and a pair of retractable wheel leg assemblies arranged on both sides of the main unit (1), and also includes two rotational degree-of-freedom limiting components (3). The retractable wheel assembly includes a four-bar linkage, a leg retractable joint (5) for driving the four-bar linkage to unfold or retract, and a drive wheel assembly located at the end of the four-bar linkage. The retractable wheel assembly corresponds one-to-one with the rotational degree-of-freedom limiting assembly (3). The pair of retractable wheel leg assemblies are arranged symmetrically along a vertical symmetry plane. The front-to-back direction of the main unit (1) is parallel to the vertical symmetry plane, and the forward direction of the drive wheel assembly is parallel to the vertical symmetry plane. In the corresponding extension and retraction wheel assembly and rotational degree of freedom limiting assembly (3): the rotational degree of freedom limiting assembly (3) includes a front and back swing joint (301) for driving the leg extension and retraction joint (5) to swing back and forth and an inside and outside swing joint (302) for driving the front and back swing joint (301) to swing inward and outward. When the front and back swing joint (301) swings inward, the drive wheel assembly is close to the vertical symmetry plane. When the front and back swing joint (301) swings outward, the drive wheel assembly is away from the vertical symmetry plane. The four-bar linkage includes a first link (401), a second link (402), a third link (403), and a fourth link (404). In a retractable leg assembly: the leg retractable joint (5) includes a leg joint body and a retractable drive shaft that can rotate relative to the leg joint body. The first link (401) is connected to the leg joint body. One end of the second link (402) is connected to the retractable drive shaft. The other end of the second link (402) is hinged to one end of the fourth link (404). One end of the third link (403) is hinged to the first link (401). The other end of the third link (403) is hinged to the middle of the fourth link (404). A rear torsion spring (201) is provided at the hinge joint between the second link (402) and the fourth link (404). One end of the rear torsion spring (201) is connected to the second link (402), and the other end of the rear torsion spring (201) is connected to the fourth link (404). A front torsion spring (202) is provided at the hinge joint between the third link (403) and the fourth link (404). One end of the front torsion spring (202) is connected to the third link (403), and the other end of the front torsion spring (202) is connected to the fourth link (404). When the four-bar linkage is retracted to its ultimate retracted position, the rear torsion spring (201) is twisted and stores energy, and the front torsion spring (202) is twisted and stores energy.

2. The wheeled-legged robot according to claim 1, characterized in that, In the corresponding extension and retraction wheel assembly and rotational degree of freedom limiting assembly (3): when the front and rear swing joint (301) drives the leg extension and retraction joint (5) to swing back and forth, the rotation center line of the leg extension and retraction joint (5) coincides with the rotation center line of the extension and retraction drive shaft. When the inward and outward swing joint (302) drives the front and rear swing joint (301) to swing inward and outward, the rotation center line of the front and rear swing joint (301) is parallel to the front and rear direction of the main unit (1).

3. A wheeled-legged robot according to claim 1 or 2, characterized in that, The drive wheel assembly includes a drive wheel body (203) disposed at the other end of the fourth link (404) and a hub motor (6) disposed on the drive wheel body (203), the hub motor (6) being used to drive the drive wheel body (203) to rotate.

4. A wheeled-legged robot according to claim 3, characterized in that, The hub motor (6) includes a fixed housing (601), a rotating housing (602), a motor stator (603), a motor rotor (604), and a motor drive plate (605). In a drive wheel assembly: the fixed housing (601) is fixed to the drive wheel body (203), the motor stator (603) is fixed on the fixed housing (601), the motor rotor (604) includes a rotor shaft (604.1) and a rotor body (604.2) connected to the rotor shaft (604.1), the rotor body (604.2) is sleeved outside the motor stator (603), the motor stator (603) has an internal space, and the motor drive plate (605) is located in the internal space of the stator.

5. A wheeled-legged robot according to claim 1 or 2, characterized in that, It also includes a sensing module (7), the power source (2) includes a power battery, the sensing module (7), the rotational degree of freedom limiting component (3) and the power battery are arranged in sequence along the front and rear direction of the host (1), the power battery is detachably connected to the rear side of the host (1), the sensing module (7) is set on the front side of the host (1), and the leg joint body and the rotational degree of freedom limiting component (3) are located below the host (1).

6. A wheeled-legged robot according to claim 5, characterized in that, The vertical projection of the front and rear swing joint (301) overlaps with the vertical projection of the host (1), and the vertical projection of the inner and outer swing joint (302) overlaps with the vertical projection of the host (1). The extension and retraction wheel leg assembly is connected to the front and rear swing joint (301) through a lateral connector (501). The lateral connector (501) includes a first connector (501.1) and a second connector (501.2). The first connector (501.1) is fixed to the second connector (501.2) by several lateral bolts (502). The vertical projection of the lateral bolts (502) is outside the vertical projection range of the host (1). When the front and rear swing joint (301) drives the leg extension and retraction joint (5) to swing back and forth, the angle between the rotation center line of the leg extension and retraction joint (5) and the axis of any lateral bolt (502) is M degrees, where M is greater than or equal to 45 degrees and M is less than or equal to 90 degrees. The first connector (501.1) is connected to the forward and backward swing joint (301), and the second connector (501.2) is connected to the leg extension and retraction joint (5).

7. A wheeled-legged robot according to claim 1 or 2, characterized in that, The host (1) is provided with a front support wheel group and a rear support wheel group. When each four-bar linkage is in the extreme retracted position, the lowest point of the front support wheel group, the lowest point of the drive wheel (203) and the lowest point of the rear support wheel group are all in the same plane. The front support wheel assembly includes two front swivel wheels (101), and the rear support wheel assembly includes two rear swivel wheels (102).

8. A wheeled-legged robot according to claim 1 or 2, characterized in that, The retractable wheel assembly also includes a locking assembly, which includes a first locking structure and a second locking structure that can be locked and fixed with the first locking structure. In a retractable wheel assembly: both the first locking structure and the second locking structure are mounted on a four-bar linkage. When the first locking structure and the second locking structure are locked and fixed, the four-bar linkage remains in the extreme retracted position.

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