Wheel-leg mechanism with variable ground contact characteristics

Abstract

The application belongs to the technical field of robots, and particularly relates to a wheel-leg mechanism with variable ground contact characteristics; the wheel-leg mechanism comprises a first thigh, a second thigh, a first shank, a second shank and a wheel, the lower end of the second shank is provided with two groups of brake assemblies; the wheel is composed of twelve blocks, the outer side of the twelve blocks of the wheel is wrapped with contact shells with different stiffness characteristics, and one end of the wheel shaft is fixedly provided with an absolute encoder. The wheel of the application is composed of twelve blocks, and the stiffness characteristics of the outer material of each block are different, so that when the wheel-leg mechanism walks as a foot end, the side swing angle of the leg is controlled or when the spliced wheel contacts with the ground, the front and back movement of the leg is controlled, the contact position of the spliced wheel and the ground can be changed, the foot-ground contact characteristics are changed, and thus the contact shells with different stiffness characteristics wrapped on the outer side of the wheel can be selected to contact with the ground according to different terrains.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of robots, and particularly relates to a wheel-leg mechanism with variable ground contact characteristics. BACKGROUND

[0002] Legged robots have wide application prospects in ground tasks such as inspection and search and rescue because of their flexible movement and strong terrain adaptability. The foot end of a legged robot will continuously impact the ground during movement, and reducing the impact force is beneficial to improving the stability of the movement of the legged robot. There are mainly three methods to reduce the impact force, one is to increase the elasticity of the leg joint, one is to use an elastic material as the material of the foot end, and the other is to add an elastic ankle joint between the foot end and the lower leg. At present, the three methods can all achieve the purpose of reducing the impact force, but due to the unadjustable ground contact characteristics, such design is often only suitable for specific conditions of the terrain, and may not have good effects on other terrains, or even reduce the stability of the movement of the legged robot. SUMMARY

[0003] In view of the deficiencies of the prior art, the purpose of the present disclosure is to provide a wheel-leg mechanism with variable ground contact characteristics to solve the deficiencies of the prior art.

[0004] The purpose of the present disclosure can be achieved by the following technical solutions.

[0005] A wheel-leg mechanism with variable ground contact characteristics comprises a first upper leg, a second upper leg, a first lower leg, a second lower leg and a wheel, the first upper leg and the second upper leg are hinged to form a first pitch knee joint, the lower end of the second upper leg and the upper end of the first lower leg are hinged to form a second pitch knee joint, the lower end of the first lower leg is fixedly connected with a connecting block, the lower end of the connecting block is slidingly connected with the second lower leg, and the lower end of the second lower leg is fixedly connected with the axle of the wheel.

[0006] The second lower leg comprises two support vertical rods and a connecting horizontal rod, the two support vertical rods are fixedly connected through the connecting horizontal rod, and the lower end of the second lower leg is provided with two groups of brake assemblies.

[0007] The wheel is composed of twelve blocks, and the outer sides of the twelve blocks of the wheel are wrapped with contact shells with different stiffness characteristics, and one end of the axle of the wheel is fixedly provided with an absolute encoder.

[0008] Further, the brake assembly comprises a motor, a gear, a rack, a first limiting block, a second limiting block and a brake pad, the motor is two, and the motor is installed at the lower end of the connecting horizontal rod.

[0009] Further, the absolute encoder is connected with the motor through signal conversion and a single-chip microcomputer to establish a communication connection; the single-chip microcomputer is installed at the side end of the motor.

[0010] Further, the side end of each of the two support vertical rods is provided with a first through hole, and the two first through holes are located at the same horizontal position, and the rotating shaft of the motor passes through the first through hole and is fixedly connected with a gear.

[0011] Further, the side end of the gear is engaged with a rack, and the lower end of the rack is fixedly connected with a first limiting block.

[0012] Further, the outer side of the side surface of the support vertical rod is provided with a second limiting block, the second limiting block is connected with the support vertical rod through a spring, the side end of the support vertical rod close to the second limiting block is provided with a second through hole, one end of the second limiting block close to the support vertical rod is provided with a protruding column, the protruding column passes through the second through hole, and the other end of the protruding column away from the second limiting block is fixedly installed with a brake pad.

[0013] Further, the first limiting block and the second limiting block are equal in size, and both the first limiting block and the second limiting block are in the shape of a triangular prism; in the initial position, the first limiting block and the second limiting block are not attached together, and when the first limiting block moves downward, the second limiting block moves towards the direction of the wheel.

[0014] Further, the lower end of the first limiting block is provided with a notch, and the side surface of the second limiting block is fixedly connected with a blocking block, and when the first limiting block and the second limiting block are in complete contact, the blocking block is just placed in the notch.

[0015] Further, the side end of the support vertical rod is provided with a sliding groove, the connecting block is slidingly connected with the second lower leg, and a buffer spring is fixedly installed between the connecting block and the second lower leg.

[0016] Further, the upper end of the buffer spring is fixedly connected with the lower end of the connecting block, and the lower end of the buffer spring is fixedly connected with the upper end of the connecting cross rod.

[0017] The nouns, conjunctions or adjectives involved in the above technical solutions are explained as follows:

[0018] Hinge: Hinge, refers to the connection with a hinge. Commonly used in the connection of two parts of machines, vehicles, doors, windows, devices, and the connection between two devices connected by hinge is not separable, but they have conditional relative movement.

[0019] Fixed connection: the connection between two parts connected with each other cannot move relative to each other, which is called fixed connection.

[0020] Gear, rack: the working principle of gear rack is to convert the rotary motion of gear into reciprocating linear motion of rack, or convert the reciprocating linear motion of rack into rotary motion of gear.

[0021] The beneficial effects of the present application are:

[0022] 1、The motor, gear, rack, first limiting block, second limiting block and brake pad are arranged at the second shank of the present application, when the motor is controlled to fix the wheels through the brake assembly, the originally rolling wheels can realize foot type walking, so that the wheel leg structure is changed from wheel type rolling mode to foot type walking mode, so that the robot with the wheel leg structure as the foot has the rolling function of the wheel robot and the walking function of the foot robot.

[0023] 2、The wheels of the present application are composed of twelve blocks, and the stiffness characteristics of the outer materials of each block are different, so that when the wheel leg mechanism walks as a foot, the side swing angle of the leg is controlled or the front and rear movement of the leg is controlled when the spliced wheel contacts the ground, the contact position of the spliced wheel and the ground can be changed, so that the foot-ground contact characteristics are changed; so that the material of the wheel in contact with the ground can be selected according to different terrains. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0025] Figure 1 is a schematic diagram of the overall structure of the embodiment of the present application;

[0026] Figure 2 is a front view of the embodiment of the present application;

[0027] Figure 3 is a schematic diagram of the structure of the second shank of the embodiment of the present application Figure 1 ;

[0028] Figure 4 is a schematic diagram of the structure of the second shank of the embodiment of the present application Figure 2 ;

[0029] Figure 5 is a schematic diagram of the structure of the second shank of the embodiment of the present application Figure 3 ;

[0030] Figure 6 is a schematic diagram of the structure of the wheel of the embodiment of the present application;

[0031] Figure 7A first pitch knee joint and a first pitch knee joint movement schematic diagram in the embodiments of the present disclosure;

[0032] Figure 8 A roll hip joint movement schematic diagram in the embodiments of the present disclosure.

[0033] Marked in the figure: 1, first thigh; 2, second thigh; 3, first shank; 4, second shank; 5, wheel; 7, connecting block; 8, wheel axle; 9, support vertical rod; 10, connecting cross rod; 11, block; 12, absolute encoder; 13, motor; 14, gear; 15, rack; 101, first limit block; 102, second limit block; 201, first through hole; 202, second through hole; 16, convex column; 17, brake pad; 18, notch; 19, blocking block; 20, sliding groove; 21, buffer spring; 22, contact shell; 23, spring; 24, rotating shaft; 25, single-chip microcomputer; 301, first pitch knee joint; 302, first pitch knee joint. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present disclosure will be described clearly and completely below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present disclosure.

[0035] As Figure 1 , Figure 7As shown, a wheel-leg mechanism with variable ground contact characteristics includes a first thigh 1, a second thigh 2, a first shank 3, a second shank 4, and a wheel 5. In some embodiments, the upper end of the first thigh 1 is hinged to the connection of the robot body, forming a roll hip joint, which can realize the side swing of the wheel-leg mechanism. The first thigh 1 and the second thigh 2 are hinged, forming a first pitch knee joint 301. The lower end of the second thigh 2 and the upper end of the first shank 3 are hinged, forming a second pitch knee joint 302. The lower end of the first shank 3 is fixedly connected with a connecting block 7, the lower end of the connecting block 7 is slidingly connected with the second shank 4, and the lower end of the second shank 4 is fixedly connected with the wheel shaft 8 of the wheel 5. The second shank 4 includes two support vertical rods 9 and a connecting horizontal rod 10, the two support vertical rods 9 are fixedly connected through the connecting horizontal rod 10, and the lower end of the second shank 4 is provided with two groups of brake assemblies. The wheel 5 is assembled by twelve blocks 11, the outer side of the twelve blocks 11 of the wheel 5 is wrapped with contact shells 22 with different stiffness characteristics, and one end of the wheel shaft 8 of the wheel 5 is fixedly installed with an absolute encoder 12. The absolute encoder 12 converts the signal into a digital signal through the driver built-in the absolute encoder 12, and then realizes the control of the motor 13 through the working of the single-chip microcomputer 25, so as to establish the communication connection between the absolute encoder 12 and the motor 13. The foot end of the wheel-leg mechanism ensures that the wheel 5 can always be in rolling contact with the ground when the motor 13 is not in action through the first pitch knee joint 301 and the second pitch knee joint 302. When the wheel 5 needs to be applied to the ground of different terrains, the wheel 5 will be in contact and rolling with the ground to provide friction for the body to maintain balance, and then the brake assembly is controlled to stop the wheel 5 from rotating, so that the contact shell 22 wrapped outside the wheel 5 applied to the terrain is in contact with the ground, and the contact shell 22 with the specific stiffness is always in contact with the ground.

[0036] In some embodiments, as Figure 3 、 Figure 4 and Figure 5As shown, the second lower leg 4 comprises two support vertical poles 9 and a connecting horizontal pole 10, the two support vertical poles 9 are fixedly connected through the connecting horizontal pole 10, the lower end of the connecting horizontal pole 10 is provided with two motors 13, the side end of the two support vertical poles 9 is provided with two first through holes 201, the two first through holes 201 are in the same horizontal position, the rotating shaft 24 of the motor 13 penetrates through the first through hole 201, the end of the rotating shaft 24 away from the motor 13 is fixedly connected with a gear 14, the side end of the gear 14 is engagedly connected with a rack 15, the lower end of the rack 15 is fixedly connected with a first limiting block 101, the outer side of the side end surface of the support vertical pole 9 is provided with a second limiting block 102, the second limiting block 102 and the support vertical pole 9 are connected through a spring 23, the side end of the support vertical pole 9 is provided with a second through hole 202 at the position close to the second limiting block 102, the end of the side end of the second limiting block 102 close to the support vertical pole 9 is provided with a protruding column 16, the protruding column 16 penetrates through the second through hole 202, the end of the protruding column 16 away from the second limiting block 102 is fixedly installed with a brake pad 17; the initial state of the brake assembly is that the first limiting block 101 and the second limiting block 102 are attached.

[0037] The preferred examples of the present application are further described and supplemented.

[0038] On the basis of the above-mentioned embodiments, preferably, Figure 2 and Figure 3As shown, the side end of the support vertical rod 9 is provided with a sliding groove 20, the connecting block 7 is slidably connected with the second shank 4, the connecting block 7 and the second shank 4 are fixedly installed with a buffer spring 21, the upper end of the buffer spring 21 is fixedly connected with the lower end of the connecting block 7, and the lower end of the buffer spring 21 is fixedly connected with the upper end of the connecting horizontal rod 10; the connecting block 7 is slidably connected with the second shank 4, and the buffer spring 21 is arranged between the connecting block 7 and the second shank 4, so that when the wheel leg mechanism falls from a higher position to a lower position during rolling, the buffer spring 21 can offset most of the impact force, and damage to the parts of the mechanism caused by excessive impact force can be avoided.

[0039] On the basis of the above-mentioned embodiments, preferably, as shown in Figure 4 and Figure 5 As shown, the first limiting block 101 and the second limiting block 102 are equal in size, and both the first limiting block 101 and the second limiting block 102 are in the shape of a triangular prism; when the first limiting block 101 moves downward, the first limiting block 101 and the second limiting block 102 can be in close contact; the lower end of the first limiting block 101 is provided with a notch 18, and the side end surface of the second limiting block 102 is fixedly connected with a blocking block 19; when the first limiting block 101 and the second limiting block 102 are in complete contact, the blocking block 19 is just placed in the notch 18; in the present application, the notch 18 is arranged at the first limiting block 101, and the blocking block 19 is arranged at the second limiting block 102, so that after the gear 14 drives the rack 15 to move downward, the first limiting block 101 contacts the second limiting block 102, and the first limiting block 101 extrudes the second limiting block 102; when the notch 18 on the first limiting block 101 and the blocking block 19 on the second limiting block 102 are in complete cooperation, excessive braking caused by the delay of the rotation of the motor 13 is reduced, the wear of the brake pad 17 is reduced, and the brake pad 17 can resist the wheel 5 for a long time.

[0040] Working principle: under natural conditions, when the brake assembly is not working, the first limiting block 101 and the second limiting block 102 are not in contact, and the wheel-leg mechanism can perform rolling motion; when the wheel-leg needs to perform foot-end walking, the foot-end wheel 5 will first contact the ground to make the wheel 5 roll through the friction between the wheel 5 and the ground, and then the absolute encoder 12 reads the angle through which the wheel 5 turns, and then the signal is transmitted to the single-chip microcomputer 25 through the signal change, so as to know the position of the current required rigidity of the contact shell 22 outside the wheel 5, and then the single-chip microcomputer 25 controls the two motors 13 connected to the lower end of the connecting cross rod 10 to make the motors 13 rotate forward, which drives the gears 14 on both sides of the supporting vertical rod 9 to rotate, and then the gears 14 drive the rack 15 to move downward, thereby driving the first limiting block 101 to move downward, when the lower end of the first limiting block 101 contacts the upper end of the second limiting block 102, the first limiting block 101 extrudes the second limiting block 102, so that the second limiting block 102 moves in the direction facing the wheel 5, thereby driving the protruding column 16 to move in the direction facing the wheel 5, so that the brake pad 17 stops the wheel 5 from rotating; when the side end surface of the first limiting block 101 is in full contact with the side end surface of the second limiting block 102, the notch 18 at the first limiting block 101 cooperates with the blocking block 19 at the second limiting block 102, thereby reducing the excessive braking caused by the untimely stop of the rotation of the motor 13 and reducing the wear of the brake pad 17, at this time, the brake pad 17 always extrudes the wheel 5, and when the wheel 5 stops rotating, the wheel 5 originally used for rolling can be used for foot-end walking; during walking, when different wheels 5 with different materials need to contact different terrains, the first thigh 1 is controlled to change the side swing angle, so that the contact angle of the wheel 5 with the ground changes; then the absolute encoder 12 records the rolling condition of the wheel 5, and then the relationship between the encoder and the motor 13 is established, and the brake assembly is used to stop the wheel 5 from rolling, so that the specific rigidity contact shell 22 of the wheel 5 applied to the terrain contacts the ground.

[0041] In the description of this specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0042] The above shows and describes the basic principles, main features and advantages of the present disclosure. Those skilled in the art should understand that the present disclosure is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present disclosure, and various changes and improvements can be made to the present disclosure without departing from the spirit and scope of the present disclosure, and all such changes and improvements fall within the scope of the claimed present disclosure.

Claims

1. A wheel-leg mechanism with variable ground contact characteristics, characterized in that, Includes a first thigh (1), a second thigh (2), a first calf (3), a second calf (4), and a wheel (5). The first thigh (1) and the second thigh (2) are hinged to form a first pitching knee joint (301). The lower end of the second thigh (2) and the upper end of the first calf (3) are hinged to form a second pitching knee joint (302). The lower end of the first calf (3) is fixedly connected to a connecting block (7). The lower end of the connecting block (7) is slidably connected to the second calf (4). The lower end of the second calf (4) is fixedly connected to the axle (8) of the wheel (5). The second lower leg (4) includes two supporting vertical rods (9) and a connecting horizontal rod (10). The two supporting vertical rods (9) are fixedly connected by the connecting horizontal rod (10). The lower end of the second lower leg (4) is provided with two sets of brake assemblies. The wheel (5) is made up of twelve pieces (11). The outer sides of the twelve pieces (11) of the wheel (5) are all wrapped with contact shells (22) with different stiffness characteristics. An absolute encoder (12) is fixedly installed at one end of the wheel axle (8) of the wheel (5). The brake assembly includes a motor (13), a gear (14), a rack (15), a first limiting block (101), a second limiting block (102), and a brake pad (17); A second limiting block (102) is provided on the outer side of the side end face of the supporting vertical rod (9). The second limiting block (102) is connected to the supporting vertical rod (9) by a spring (23). A second through hole (202) is provided on the side end of the supporting vertical rod (9) near the second limiting block (102). A protruding post (16) is provided on the side end of the second limiting block (102) near the supporting vertical rod (9). The protruding post (16) passes through the second through hole (202). A brake pad (17) is fixedly installed on the end of the protruding post (16) away from the second limiting block (102). The first limiting block (101) and the second limiting block (102) are of equal size, and both the first limiting block (101) and the second limiting block (102) are triangular prisms. In the initial position, the first limiting block (101) and the second limiting block (102) are not attached together. When the first limiting block (101) moves downward, the second limiting block (102) moves toward the wheel (5).

2. The wheel-leg mechanism with variable ground contact characteristics according to claim 1, characterized in that, There are two motors (13), and both motors (13) are installed at the lower end of the connecting crossbar (10).

3. The wheel-leg mechanism with variable ground contact characteristics according to claim 2, characterized in that, The absolute encoder (12) and the motor (13) establish a communication connection with the microcontroller (25) through signal conversion; the microcontroller (25) is installed on the side of the motor (13).

4. The wheel-leg mechanism with variable ground contact characteristics according to claim 2, characterized in that, Both of the two support rods (9) have a first through hole (201) at their side ends. The two first through holes (201) are at the same horizontal position. The shaft (24) of the motor (13) passes through the first through hole (201) and is fixedly connected to a gear (14).

5. A wheel-leg mechanism with variable ground contact characteristics according to claim 2, characterized in that, The gear (14) is meshed with a rack (15) at its side end, and a first limiting block (101) is fixedly connected to the lower end of the rack (15).

6. A wheel-leg mechanism with variable ground contact characteristics according to claim 2, characterized in that, The lower end of the first limiting block (101) is provided with a notch (18), and the side end face of the second limiting block (102) is fixedly connected to the stop block (19). When the first limiting block (101) and the second limiting block (102) are in complete contact, the stop block (19) is just placed in the notch (18).

7. A wheel-leg mechanism with variable ground contact characteristics according to claim 1, characterized in that, The side end of the supporting vertical rod (9) is provided with a sliding groove (20), the connecting block (7) is slidably connected to the second lower leg (4), and a buffer spring (21) is fixedly installed between the connecting block (7) and the second lower leg (4).

8. A wheel-leg mechanism with variable ground contact characteristics according to claim 7, characterized in that, The upper end of the buffer spring (21) is fixedly connected to the lower end of the connecting block (7), and the lower end of the buffer spring (21) is fixedly connected to the upper end of the connecting crossbar (10).

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