WO2018133191A1

WO2018133191A1 - Chassis vehicle

Info

Publication number: WO2018133191A1
Application number: PCT/CN2017/077392
Authority: WO
Inventors: 庄彬
Original assignee: 深圳市大疆创新科技有限公司
Priority date: 2017-01-18
Filing date: 2017-03-20
Publication date: 2018-07-26
Also published as: CN109641628A; CN206749955U

Abstract

A chassis vehicle (10), comprising: a chassis body (1) and wheel legs (2) used for supporting the chassis body (1); each wheel leg (2) comprises a frame (21), and a travelling mechanism, a lifting mechanism (4) and a roller assembly which are provided on the frame (21), wherein the roller assembly comprises rollers (323); the travelling mechanism is connected to the roller (323) assembly to drive the rollers (323) to roll; auxiliary wheels (11) are provided on the chassis body (1); the frame (21) can be adjusted by the lifting mechanism to move up and down relative to the chassis body (1) so as to form an adjustable height difference between the auxiliary wheels (11) and the rollers (323). The chassis vehicle (10) uses each wheel leg (2) as an independent lifting module, the wheel legs (2) are not interfered with each other in mechanism motion and match with each other in motion control, and the wheel legs (2) are adapted to different terrains by means of deformation.

Description

Chassis car

Technical field

The invention relates to the field of robot technology, and in particular to a wheel and leg type chassis vehicle.

Background technique

In order to expand the field of robotics, it is necessary to adapt to various types of road conditions, including uphill, downhill, rugged mountain roads, obstacles and so on.

For road conditions such as uphill and downhill, if the center of gravity of the robot is not well balanced, it is easy to fall over during the travel process, especially when the acceleration is too large. For uneven terrain such as rugged mountain roads and lunar surfaces, the road surface is uneven. It is no small test to suspend the suspension of the chassis of the robot; for obstacles such as steps, the robot needs to be able to climb flexibly and steadily.

The above road conditions may cause instability of the robot body, affecting the use of the mounting device and affecting the operation of the robot. Therefore, how to make the robot adapt to the above various types of terrain conditions is very necessary for the popularization of robots, the exploration of more unknown areas for human beings, and the operation in hazardous environments.

The existing robots can be divided into: wheeled robots, legged robots, crawler-type robots, etc., each of which has its own working terrain. With the development of science and technology, more and more unknown areas need to be developed. More and more dangerous environments require robots to replace human exploration. Therefore, more and more complex robots (wheel-legged robots, crawler wheeled robots, etc.) need to be developed. come out. However, the existing mobile robot's chassis design has poor adaptability, especially in the case of unpredictable terrain, and has the disadvantages of poor performance of ups and downs and obstacles and inflexibility.

Summary of the invention

In view of this, the present invention proposes an adaptively adjustable chassis vehicle to solve the above technical problems.

According to an embodiment of the present invention, a chassis vehicle is provided, comprising: a chassis body, and a wheel leg for supporting the chassis body; wherein the wheel leg includes a frame and a frame provided on the frame a traveling mechanism, a lifting mechanism, and a roller assembly; wherein the roller assembly includes a roller, the traveling mechanism is coupled to the roller assembly to roll the roller, and the chassis body is provided with a secondary wheel, and the frame can be The lifting mechanism is adjusted to move up and down with respect to the chassis body such that the auxiliary wheel and the roller have an adjustable height difference.

The technical solution provided by the embodiment of the present invention may include the following beneficial effects: the chassis car of the present invention acts as an independent lifting module through each wheel leg, does not interfere with each other in the movement of the mechanism, cooperates with each other in motion control, and deforms the wheel leg through To adapt to the terrain of different situations.

The above general description and the following detailed description are intended to be illustrative and not restrictive.

DRAWINGS

1 is a schematic overall structural view of a chassis truck according to an exemplary embodiment of the present application;

FIG. 2 is another schematic perspective view of a chassis truck according to an exemplary embodiment of the present application; FIG.

3 is a schematic structural view of a leg of a chassis vehicle according to an exemplary embodiment of the present application;

4 is an exploded perspective view of a wheel leg of a chassis car according to an exemplary embodiment of the present application.

detailed description

The invention will be described in detail below in conjunction with the specific embodiments shown in the drawings. However, the embodiments are not intended to limit the invention, and the structural, method, or functional changes made by those skilled in the art in accordance with the embodiments are included in the scope of the present invention.

Some embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

As shown in FIG. 1, the chassis 10 of the present invention includes a chassis body 1, and a plurality of wheel legs 2 for supporting the chassis body 1. In the present invention, the number of the wheel legs 2 is not limited, and may be any number of wheel legs 2, each of which can be used as an independent lifting mechanism 4, which does not interfere with each other in the movement of the mechanism, and is controlled by motion. In cooperation with the system, the chassis 10 of the present invention is adapted to the terrain of different conditions by deforming the wheel legs 2. The chassis 10 can be used to mount a detection/surveillance robot, and can ensure the stability of the detection/monitoring robot on the chassis 10, thereby enabling the detection robot to perform various types of detection/monitoring tasks more stably and efficiently.

As shown in FIGS. 1 to 4, the wheel leg 2 includes a frame 21, and a traveling mechanism, a lifting mechanism 4, and a roller assembly provided on the frame 21. Wherein, the roller assembly includes a roller 323, and the traveling mechanism is coupled to the roller assembly to roll the roller 323, thereby driving the chassis 10 to move. The wheel leg 2 can also be operated by the lifting mechanism 4 such that the wheel leg 2 can be moved relative to the chassis body 1 to adjust the distance between the roller 323 and the chassis body 1.

The chassis main body 1 is provided with an auxiliary wheel 11, wherein the frame 21 can be adjusted by the lifting mechanism 4 to move up and down with respect to the chassis main body 1 so that the auxiliary wheel 11 and the roller 323 have an adjustable height difference. The auxiliary wheel 11 is located in front of the roller assembly and serves to assist the support of the chassis body 1 when the wheel leg 2 moves up and down relative to the chassis body 1. For example, when the wheel leg 2 passes through the pothole, the roller 323 enters the pothole. Generally, the chassis body 1 will have a center of gravity inclination due to the wheel leg 2 entering the pothole, and the chassis truck 10 of the present invention has the auxiliary wheel. The support and the driven rolling of the 11 can support the chassis main body 1 and enable the chassis main body 1 to continue to maintain the original running posture. At this time, by increasing the height difference between the roller 323 and the auxiliary wheel 11, the roller 323 can be timely resisted. Going to the surface of the pothole, and continuing to support and drive the chassis body 1; when the wheel leg 2 is out of the pothole, the running posture of the chassis body 1 can be maintained by gradually reducing the height difference between the roller 323 and the auxiliary wheel 11 The stability of the chassis body 1 is always guaranteed. In the present invention, the chassis 10 is provided with the auxiliary wheel 11 for each leg 2 so that each leg 2 is independently controlled and adjusted.

The frame 21 includes an upper structural frame 211, a lower structural frame 212, and a plurality of support rod bodies 213 connected between the upper structural frame 211 and the lower structural frame 212. In an alternative embodiment, the support rod body 213 includes four, which is a combination of two square aluminum tubes and two carbon rods, and four support rod bodies 213 are distributed at four corners of the frame 21, of which two The square aluminum tube and the two carbon rods are diagonally distributed to satisfy the overall structural strength of the frame 21. In this embodiment, the combination of the square aluminum tube and the carbon rod can achieve the purpose of weight reduction design while ensuring the structural strength of the frame 21. Additionally, in other embodiments of the invention, The number of the support rods 213 may not be limited. The material of the support rod body 213 may also be any material having structural strength, and the structural strength of the support frame may be ensured.

In the present invention, the traveling mechanism includes a first motor 31, and a first linkage assembly 325 coupled to the first motor 31 and the roller assembly. The first motor 31 is provided with a motor base 311. The first motor 31 is fixed on the upper structure frame 211 by the motor base 311. The first motor 31 drives the roller 323 to rotate through the first linkage assembly 325, so that the first motor 31 can drive the motor 31. The movement of the chassis car 10. In this embodiment, the first motor 31 is disposed on the upper structural frame 211, and the power is transmitted to the roller 323 on the lower structural frame 212 through the first linkage assembly 325. The arrangement can effectively reduce the lateral dimension of the roller assembly. Conducive to the wheel leg 2 through the narrow area.

In an optional embodiment, the first linkage assembly 325 includes a first timing belt, and the rotating shaft end of the first motor 31 is provided with a synchronous wheel, and one end of the first timing belt is connected to the synchronous wheel of the first motor 31. The other end of the first timing belt is sleeved on the roller assembly, and the first motor 31 rotates and drives the first timing belt to drive, thereby driving the roller 323 to rotate. In still another alternative embodiment, the first linkage assembly 325 can also be a gear combination that allows the motor to drive the roller 323 to rotate by a cooperation between the plurality of gears. Of course, it is also possible to adopt a structure such as a screw rod, and the first linkage assembly 325 which can satisfy the rotation of the motor drive roller 323 is not included in the present invention.

The roller assembly further includes an axle seat 321 fixed to the frame 21 and an axle 322 pivotally coupled to the axle seat 321 . The roller 323 is fixed to the axle 322 and is rotatably coupled to the axle seat 321 via the axle 322. In this embodiment, the axle seat 321 is two and fixed on both sides of the lower structural frame 212, so that the roller 323 can be stably connected to the frame 21 and can be rotated by the axle 322 as an axis. In a preferred embodiment, the roller 323 is a McLaren wheel that provides an omnidirectional movement for use in terrains of different conditions.

Further, the roller assembly further includes a first synchronous wheel 324 disposed on the axle 322. The first synchronous wheel 324 is located on the side of the roller 323, wherein the axle 322 and the roller 323 are coaxially rotated with the first synchronous wheel 324. . In this embodiment, the first motor 31 drives the first synchronous wheel 324 to rotate by the first linkage assembly 325 to drive the roller 323 to rotate.

The wheel leg 2 further includes a guard wheel assembly 34 disposed on the frame 21, the guard wheel assembly 34 being located in the axle seat The outer side of 321 is used to protect the roller assembly. In the present embodiment, the guard wheel assembly 34 includes a guard plate 341 and guard wheels 342 respectively disposed at opposite ends of the guard plate 341. The traveling direction of the guard wheel 342 is consistent with the traveling direction of the roller 323, and can serve as an emergency support. The protective effect of continuous travel.

In the present invention, the elevating mechanism 4 includes a lifting body 41, a second motor 44 fixed to the elevating body 41, and a second linkage assembly coupled to the second motor 44 and the elevating body 41. Wherein, the second motor 44 drives the lifting body 41 to move relative to the frame 21 through the second linkage assembly, thereby causing the frame 21 to rise or fall relative to the lifting body 41. In this embodiment, the lifting body 41 is fixed to the chassis body 1, and the driving force generated by the second motor 44 is converted to the frame 21 by the lifting body 41, so that the frame 21 can be raised or lowered relative to the lifting body 41, that is, the frame. 21 is raised or lowered relative to the chassis body 1. The auxiliary wheel 11 is fixed to the chassis main body 1, and the roller 323 is fixed to the frame 21, and the frame 21 is raised or lowered with respect to the chassis main body 1, that is, the height difference between the roller 323 and the auxiliary wheel 11 is adjusted.

Further, the lifting mechanism 4 further includes a guiding member 421 fixed to the frame 21, and the guiding member 421 is located in the frame 21 and can be coupled to the frame 21 by a support or an adapter plate or the like fixed thereto. The second linkage assembly includes a fitting 431 that is coupled to the guide 421, wherein the fitting 431 is relatively moved in the axial direction of the guide 421 by the second motor 44. In this embodiment, the engaging member 431 can be rotated by the second linkage assembly, and then the engaging member 431 is rotated relative to the guiding member 421 such that the entire frame 21 and the roller assembly are raised or lowered in the axial direction of the guiding member 421. In an alternative embodiment, the guiding member 421 is a screw rod, and the fitting member 431 is a screw nut that is coupled to the lifting body 41.

The second linkage assembly further includes a second synchronization wheel 432 disposed on the mating member 431 and a second timing belt 433 sleeved on the second motor 44 and the second synchronization wheel 432. The second motor 44 drives the second timing wheel 432 to rotate by the second timing belt 433 to drive the mating member 431 to rotate relative to the guide member 421. Specifically, the rotating end of the second motor 44 is provided with a synchronous wheel, one end of the second synchronous belt 433 is sleeved on the synchronous wheel of the second motor 44, and the other end of the second synchronous wheel 432 is sleeved on the second synchronous wheel. At 432, the second motor 44 can drive the mating member 431 to rotate. Of course, in other embodiments of the invention, the second linkage assembly may also be a mating combination of a plurality of gears. In addition, the second linkage assembly further includes a limiting member 434 disposed under the second synchronous wheel 432 for defining the second synchronous wheel 432 on the mating member 431.

In the present invention, the lifting body 41 includes an upper support plate 411 and a lower support plate 412 which are oppositely disposed. The upper support plate 411 and the lower support plate 412 are fixedly coupled to the chassis main body 1, and the second linkage assembly is located on the upper support plate 411 and the Between the lower support plates 412, the lifting body 41 can protect the operation of the second linkage assembly by the motor, and avoid interference of other components in the wheel legs 2 when the lifting mechanism 4 operates. The upper support plate 411 is provided with a sleeve 413. The support rod body of the frame 21 is inserted into the sleeve 413 and slidable relative to the sleeve 413. This can facilitate the frame 21 to rise or fall relative to the lifting body 41.

Further, the second linkage assembly further includes an upper bearing 435 fixed to the upper support plate 411, and a lower bearing 436 fixed to the lower support plate 412. The upper support plate 411 is fitted to the guide member 421 through the upper bearing 435 to slide along the guide member 421, and the lower support plate 412 is fitted to the guide member 421 through the lower bearing 436 to slide along the guide member 421, thus realizing the lift main body 41. The movement of the frame 21 relative to the chassis body 1 can be achieved after the lifting body 41 is fixed to the chassis body 1 with respect to the axial movement of the guide member 421.

The chassis main body 1 is further provided with a mechanical arm 12 fixed to the mechanical arm 12 and coupled to the chassis main body 1, and the auxiliary wheel 11 is located in front of the wheel leg 2 via the mechanical arm 12. In an alternative embodiment, the robot arm 12 is pivotally coupled to the chassis body 1 to switch the robot arm 12 between a vertical direction and a horizontal direction. Wherein, the combined structure of the mechanical arm 12 and the auxiliary wheel 11 is similar to an aircraft landing gear, and the mechanical arm 12 can be adjusted to a horizontal direction when needed; when the mechanical arm 12 is not used, the mechanical arm 12 can be folded in a vertical direction. Thus, the space occupied by the chassis 10 can be reduced.

In still another alternative embodiment, the robot arm 12 includes a first arm fixed to the chassis body 1 and a second arm to which the auxiliary wheel 11 is fixed; wherein the first arm and the second arm are controllably relative to each other, The robot arm 12 has an adjustable length. Of course, the mechanical arm 12 is not limited to the two-stage arm, and a plurality of arm structures may be disposed between the first arm and the second arm according to the required telescopic length. In this embodiment, the mechanical arm 12 may also be designed. For the telescopic structure, when needed, the second arm is withdrawn from the first arm to increase the length of the mechanical arm 12; when it is not needed, the second arm is retracted into the first arm to reduce the arm The length of 12. The manner in which the two are relatively stretchable is applicable to the first arm and the second arm of the present invention, and will not be exemplified herein.

Further, the auxiliary wheel 11 further includes a sensor unit (not shown) disposed thereon for acquiring the distance between the auxiliary wheel 11 and the ground. In this embodiment, the sensor unit may be a photoelectric sensor. Correspondingly, a control unit (not shown) is mounted on the chassis body 1. The control unit is electrically connected to the sensor unit for controlling the operation of the traveling mechanism and the lifting mechanism 4 after acquiring the signal of the sensor unit. Wherein, when the sensor unit on the auxiliary wheel 11 senses that the distance of the auxiliary wheel 11 from the ground is greater than or less than a preset value, the sensor unit sends a signal to the control unit, and the control unit controls the lifting mechanism 4 to operate. For example, when the distance detected by the photoelectric sensor is greater than a preset height difference between the auxiliary wheel 11 and the roller 323, the control unit controls the lifting mechanism 4 so that the height difference between the roller 323 and the auxiliary wheel 11 reaches the level detected by the photoelectric sensor. The distance is such that each leg 2 is individually controlled according to the terrain, and the plurality of wheel legs 2 cooperate with each other.

The chassis body 1 is further provided with a measuring unit (not shown) electrically connected to the control unit for acquiring the state value of the chassis body 1 , and the state value may include the three-dimensional attitude angle (or angular rate) of the chassis body 1 . ) and acceleration. Wherein, the control unit controls the operation of the traveling mechanism and the lifting mechanism 4 according to the state value of the chassis body 1 acquired by the measuring unit. In an optional embodiment, the measuring unit is an inertial measuring unit, and the chassis truck 10 of the present invention acquires the attitude information of the chassis body 1 in real time through the inertial measurement unit, and controls each wheel leg 2 through the control unit to maintain or Convert to a certain type of pose. For example, in different types of detected terrain, the control unit cooperates with the inertial measurement unit, and the control of the control unit ensures that the chassis body 1 is always in a horizontal state, thereby avoiding affecting the work of the mount detection robot.

In an embodiment of the invention, the chassis 10 has four wheel legs 2 including two front wheel legs 2 and two rear wheel legs 2. Wherein, the structures of the left front wheel leg 2 and the right rear wheel leg 2 are the same, the structures of the right front wheel leg 2 and the left rear leg 2 are the same, and the structures of the left front leg 2 and the right front leg 2 are mirror symmetrical, left rear The structure of the wheel leg 2 and the right rear leg 2 is mirror symmetrical. Correspondingly, there are four mechanical arms 12 and auxiliary wheels 11, and each auxiliary wheel 11 is mounted in front of the corresponding wheel leg 2 by a mechanical arm 12. Of course, the chassis truck 10 of the present invention is not limited to the four wheel legs 2, and may include any number of wheel legs 2 according to the size of the chassis body 1, and the structure of each wheel leg 2 is as shown in the above embodiment, and is not here. Let me repeat.

For the specific operation of the chassis 10, the control unit, the measuring unit, the sensor unit, the respective wheel legs 2 and the auxiliary wheels 11 are required to cooperate with each other. The present invention is specifically described by taking the upper and lower steps of the chassis 10 as an example: when the photoelectric sensor on the auxiliary wheel 11 detects the step, the auxiliary wheel 11 can be placed on the upper step, and then the left front wheel and the right front are controlled by the control unit. Wheel leg lift; when two rear wheel legs are optoelectronic The sensor detects that the two auxiliary wheels of the rear wheel legs are located behind the step, and by lifting the two rear wheel legs, during the operation, the height difference between the auxiliary wheel 11 and the roller 323 is continuously adjusted to complete the climbing of the upper step. climb. The process of lowering the step is opposite to the step of adjusting the upper step, and the principle is the same as that of the upper step, and will not be described in detail here. In addition, during the entire movement, the chassis body 1 is always horizontal (or any other posture) stable by the cooperation of the control unit and the measuring unit, wherein the control unit is also used to control the speed of the roller 323 to match the leg 2 Adjustment.

The chassis truck of the invention sets each wheel leg as an independent lifting module, does not interfere with each other in the movement of the mechanism, cooperates with each other in motion control, and the wheel legs are deformed to adapt to different terrains, so that the chassis can not only pass smoothly. Uphill, downhill, uneven unequal terrain, easy to cross obstacles, steps, etc., while at the same time in the process of travel can also ensure the horizontal stability of the chassis, especially for cloud trolleys, lunar vehicles, inspection robots, etc. The robot that mounts the device.

Other embodiments of the invention will be apparent to those skilled in the <RTIgt; The present application is intended to cover any variations, uses, or adaptations of the present invention, which are in accordance with the general principles of the present invention and include common general knowledge or conventional technical means in the art that are not disclosed in the present invention. . The specification and examples are to be regarded as illustrative only, and the true scope and spirit of the invention

It is to be understood that the invention is not limited to the details of the details of The scope of the invention is limited only by the appended claims.

Claims

A chassis truck includes: a chassis body; and a wheel leg for supporting the chassis body; wherein the wheel leg includes a frame, and a traveling mechanism, a lifting mechanism, and a roller assembly disposed on the frame; Wherein the roller assembly includes a roller, the traveling mechanism is coupled to the roller assembly to roll the roller, and the chassis body is provided with a secondary wheel, and the frame can be adjusted by the lifting mechanism relative to the The chassis body is moved up and down to have an adjustable height difference between the auxiliary wheel and the roller.
The chassis according to claim 1, wherein said traveling mechanism comprises a first motor, and a first linkage assembly coupled to said first motor and said roller assembly; wherein said first motor passes The first linkage assembly drives the roller to rotate.
The chassis according to claim 2, wherein said roller assembly further comprises an axle seat fixed to said frame, an axle pivotally coupled to said axle axle; wherein said roller is rotated by said axle Connected to the axle seat.
The chassis according to claim 3, wherein said roller assembly further comprises a first synchronous wheel disposed on said axle, said first motor driving said first synchronization by said first linkage assembly The wheel rotates to drive the roller to rotate.
A chassis according to claim 3, wherein said wheel leg further comprises a guard wheel assembly disposed on said frame, said guard wheel assembly being located outside said axle seat.
A chassis according to claim 5, wherein said guard wheel assembly includes a shield plate and guard wheels respectively disposed at opposite ends of said shield plate.
The chassis of claim 1 wherein said roller is a McLaren wheel.
The chassis according to claim 4, wherein said first linkage assembly comprises a first timing belt, one end of said first timing belt being drivingly coupled to said first motor, said first timing belt The other end is sleeved on the first synchronous wheel.
The chassis truck according to any one of claims 1 to 8, wherein the lifting mechanism includes a lifting body, a second motor fixed to the lifting body, and a second motor a second linkage assembly with the lifting body; wherein the second motor drives the lifting body to move relative to the frame by the second linkage assembly to cause the frame to ascend or descend relative to the lifting body.
A chassis truck according to claim 9, wherein said lifting mechanism further comprises a guide member fixed to said frame; said second linkage assembly comprising a fitting member coupled to said guide member; The mating member is relatively moved in the axial direction of the guide member under the driving of the second motor.
The chassis according to claim 10, wherein the second linkage assembly further comprises a second synchronous wheel disposed on the mating member and sleeved on the second motor and the second synchronous wheel a second timing belt; the second motor drives the second timing wheel to rotate by the second timing belt to drive the mating member to rotate relative to the guiding member.
A chassis according to claim 10 or 11, wherein said guide member is a screw and said mating member is a spindle nut.
The chassis of claim 11 wherein said second linkage assembly further comprises a stop member disposed below said second synchronization wheel.
The chassis truck according to claim 9, wherein the lifting body comprises an upper support plate and a lower support plate, wherein the upper support plate and the lower support plate are fixedly connected to the chassis main body, A second linkage assembly is located between the upper support plate and the lower support plate.
The chassis truck according to claim 14, wherein the upper support plate is provided with a sleeve, the frame includes a support rod body, and the support rod body is disposed in the sleeve and is slidable relative to the sleeve .
The chassis according to claim 14, wherein said second linkage assembly further comprises an upper bearing fixed to said upper support plate, and a lower bearing fixed to said lower support plate;

Wherein the upper support plate is fitted to the guide member by the upper bearing to slide along the guide member; the lower support plate is fitted to the guide member through the lower bearing to slide along the guide member.
A chassis according to claim 9, wherein said chassis body is further provided with a mechanical arm fixed to said robot arm and coupled to said chassis body.
A chassis according to claim 17, wherein said mechanical arm is pivotally connected The chassis body is configured to switch the robot arm between a vertical direction and a horizontal direction.
A chassis according to claim 18, wherein said mechanical arm includes a first arm fixed to said chassis body and a second arm to which said auxiliary wheel is fixed; wherein said first arm The second arm is controllably moved relative to each other such that the robot arm has an adjustable length.
The chassis of claim 1 wherein said secondary wheel further comprises a sensor unit disposed thereon.
A chassis according to claim 20, wherein said sensor unit is a photoelectric sensor.
The undercarriage according to claim 20, wherein the chassis body is provided with a control unit, and the control unit is electrically connected to the sensor unit for controlling the signal after acquiring the signal of the sensor unit. The traveling mechanism and the lifting mechanism operate.
The chassis according to claim 22, wherein the chassis body is further provided with a measuring unit electrically connected to the control unit for acquiring a state value of the chassis body; wherein the control The unit controls the traveling mechanism and the lifting mechanism to operate according to a state value of the chassis body acquired by the measuring unit.
A chassis according to claim 23, wherein said measuring unit is an inertial measuring unit.
A chassis according to claim 22, wherein said wheel legs are four, including two front wheel legs and two rear wheel legs; said auxiliary wheels are four, each of said auxiliary wheels Provided in front of the corresponding wheel legs;

Wherein, when the sensor unit on the auxiliary wheel senses that the distance of the auxiliary track from the ground is greater than or less than a preset value, the sensor unit sends a signal to the control unit, and the control unit controls the The lifting mechanism operates.