CN118794439A - A walking positioning method and positioning system for an EMU undercarriage inspection robot - Google Patents

Abstract

A walking positioning method and positioning system for an undercarriage inspection robot for a multiple unit train relates to a method and system for position calibration. The purpose is to overcome the problem that the existing inspection robot cannot accurately reach the target position when walking. The positioning method steps are as follows: Step 1, control the inspection robot to walk from the starting point to the end point along a straight path, and calculate the linear expected value φ of the driven wheel corresponding to the position to be detected; and obtain the linear measurement value x _k of the driven wheel collected when the kth auxiliary positioning point is detected; Step 2, control the inspection robot to walk from the end point to the starting point along a straight path, and obtain the corresponding linear measurement value y _k of the driven wheel when the kth auxiliary positioning point is detected again; Step 3, calculate the correction value of the position to be detected by the following formula: p = φ-x _k +y _k +δ _k ; Step 4, according to the correction value of the position to be detected, continue to control the inspection robot to walk to the position to be detected, and complete the walking positioning of the inspection robot.

Description

A walking positioning method and positioning system for an EMU undercarriage inspection robot

Technical Field

The invention relates to a method and system for position calibration.

Background Art

With the increasing number of EMUs in operation in recent years, the corresponding maintenance tasks undertaken by EMUs have become increasingly heavy, and the operating pressure has also increased. The daily maintenance of EMUs is mainly first-level maintenance, and each first-level maintenance is completed by 1 to 2 maintenance teams. With the gradual increase in the number of EMUs and the number of operating routes, EMU undercarriage inspection robots have emerged. However, when the inspection robot inspects the body parts, it needs to take images at close range. The deviation of the target stop position increases the risk of collision with the undercarriage of the EMU and the deviation of the image shooting angle. Therefore, the accuracy of the walking position of the inspection robot is extremely high.

The existing inspection robot is positioned by the encoder on the driving wheel, but based on the existing track conditions and usage environment, driving wheel slippage is inevitable. Only by writing the encoder value through the controller to drive the robot to walk cannot accurately reach the target position.

Summary of the invention

The purpose of the present invention is to overcome the problem that the existing inspection robot cannot accurately reach the target position when walking, and to provide a walking positioning method and a positioning system for an EMU underbody inspection robot.

The present invention provides a walking and positioning method for an EMU vehicle bottom detection robot, which is implemented based on the detection robot, and the detection robot includes a driving wheel and a driven wheel;

Here are the steps:

Step 1: Control the detection robot to walk along a straight line from the starting point to the end point, and calculate the linear expected value of the driven wheel corresponding to the position to be detected and obtaining the linear measurement value x _k of the driven wheel collected when the kth auxiliary positioning point is detected;

The position to be inspected is identified by the inspection robot after scanning the complete bottom of the EMU;

The number of auxiliary positioning points is n, and the n auxiliary positioning points are set at equal intervals on the straight path;

The kth auxiliary positioning point is an auxiliary positioning point adjacent to the position to be detected and close to the end point, and 1≤k≤n;

The driven wheel linear expected value is the driven wheel displacement obtained according to the expected number of rotations of the driven wheel, and the driven wheel linear measured value is the driven wheel displacement obtained according to the actual number of rotations of the driven wheel;

Step 2: Control the detection robot to walk along a straight path from the end point to the starting point, and when the kth auxiliary positioning point is detected again, obtain the corresponding driven wheel linear measurement value y _k ;

Step 3: Calculate the correction value of the position to be detected by the following formula:

Wherein, δ _k is the round-trip deviation value of the kth auxiliary positioning point;

Step 4: According to the correction value of the position to be detected, continue to control the detection robot to walk to the position to be detected, and complete the walking positioning of the detection robot.

Furthermore, the process of obtaining the round-trip deviation value of any auxiliary positioning point is as follows:

Step 31: Control the detection robot to walk along a straight path from the starting point to the end point, and when any auxiliary positioning point is detected, obtain the corresponding driven wheel linear measurement value a _n ;

Step 32: Control the detection robot to walk along a straight path from the end point to the starting point; and when any auxiliary positioning point is detected again, obtain the corresponding driven wheel linear measurement value bn;

Step 3. Calculate the round-trip deviation value of any auxiliary positioning point using the following formula:

δ _n = a _n - b _n .

Furthermore, the process of obtaining the round-trip deviation value of any auxiliary positioning point also includes:

Step 34: Return and execute step 31 to step 33 to obtain multiple round-trip deviation values, and calculate the arithmetic mean based on the multiple round-trip deviation values as the final round-trip deviation value.

Furthermore, step 2 also includes:

Control the detection robot to walk from the end point to the initial positioning position in a position mode;

The position mode is: first accelerate to a preset upper limit speed with a set first acceleration, then walk at a constant speed with the upper limit speed, and finally decelerate with a set second acceleration until the speed reaches 0;

The initial positioning position is the position of the robot detected when the linear measurement value of the driving wheel is equal to the linear expected value of the driving wheel;

The linear expected value of the driving wheel is calculated by the linear expected value of the driven wheel. It is calculated that the linear measurement value of the driving wheel is the driving wheel displacement obtained according to the actual number of revolutions of the driving wheel.

Furthermore, step four also includes:

Control the detection robot to move from the initial positioning position to the position to be detected in a speed mode;

The speed mode is: walking at a constant speed at the set constant speed.

Furthermore, the material of the driven wheel is at least one of polyurethane, polyvinyl chloride or polyamide.

The present invention also provides a walking positioning system for an EMU vehicle bottom detection robot, comprising a controller;

A controller, used to execute the walking positioning method of claim 5.

Furthermore, it also includes a first encoder, a second encoder, a plurality of magnetic bodies and a magnetic detection device;

The first encoder is used to obtain the linear measurement value of the driving wheel in real time;

The second encoder is used to obtain the linear measurement value of the driven wheel in real time;

A magnetic body, used as an auxiliary positioning point;

The magnetic detection device is used to detect magnetic bodies and output pulse detection signals.

Furthermore, the plurality of magnetic bodies and the magnetic detection devices are all located on the same horizontal plane.

Furthermore, the time corresponding to the rising edge of the pulse detection signal is used as the time when the corresponding auxiliary positioning point is detected.

The beneficial effects of the present invention are:

The present invention uses two encoders plus magnetic body marks to control the walking and positioning of the detection robot, uses the driving wheel and the corresponding first encoder to achieve rough position positioning, and uses the driven wheel and the corresponding second encoder to achieve precise correction. The problem of inaccurate positioning caused by the slipping of the driving wheel as a power wheel is avoided, and the cumulative error of the whole process is reduced to between two adjacent magnetic bodies through multiple magnetic bodies. The walking positioning accuracy of the detection robot is improved, and the risk of inaccurate detection is significantly reduced. It has self-learning and self-calibration functions, high stability and high positioning accuracy. For the existing device, it only needs to install magnetic bodies at equal intervals on the original track device, which is easy to operate and reduces equipment and labor costs. It is suitable for different types of railway vehicles and track environments and has broad application prospects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of an electrical structure of a walking positioning system of a motor vehicle underbody inspection robot according to the present invention;

FIG. 2 is a schematic structural diagram of the cooperation between a magnetic detection device and a detection robot in a walking positioning system of an EMU undercarriage detection robot according to the present invention.

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

Specific implementation method 1

A walking positioning method of a vehicle bottom inspection robot of an EMU in this embodiment is implemented based on the inspection robot, and the inspection robot includes a driving wheel and a driven wheel;

Here are the steps:

Step 1: Control the detection robot to walk along a straight line from the starting point to the end point, and calculate the linear expected value of the driven wheel corresponding to the position to be detected and obtaining the linear measurement value x _k of the driven wheel collected when the kth auxiliary positioning point is detected;

The position to be inspected is identified by the inspection robot after scanning the complete bottom of the EMU;

The number of auxiliary positioning points is n, and the n auxiliary positioning points are set at equal intervals on the straight path;

The kth auxiliary positioning point is an auxiliary positioning point adjacent to the position to be detected and close to the end point, and 1≤k≤n;

The driven wheel linear expected value is the driven wheel displacement obtained according to the expected number of rotations of the driven wheel, and the driven wheel linear measured value is the driven wheel displacement obtained according to the actual number of rotations of the driven wheel;

Step 2: Control the detection robot to walk along a straight path from the end point to the starting point, and when the kth auxiliary positioning point is detected again, obtain the corresponding driven wheel linear measurement value y _k ;

Step 3: Calculate the correction value of the position to be detected by the following formula:

Wherein, δ _k is the round-trip deviation value of the kth auxiliary positioning point;

Step 4: According to the correction value of the position to be detected, continue to control the detection robot to walk to the position to be detected, and complete the walking positioning of the detection robot.

Specific implementation method 2

This embodiment is a further explanation of the first embodiment. In this embodiment, the process of obtaining the round-trip deviation value of any auxiliary positioning point is as follows:

Step 31: Control the detection robot to walk along a straight path from the starting point to the end point, and when any auxiliary positioning point is detected, obtain the corresponding driven wheel linear measurement value a _n ;

Step 32: Control the detection robot to walk along a straight path from the end point to the starting point; and when any auxiliary positioning point is detected again, obtain the corresponding driven wheel linear measurement value bn;

Step 3. Calculate the round-trip deviation value of any auxiliary positioning point using the following formula:

δ _n = a _n - b _n .

The other technical features of this embodiment are exactly the same as those of the first embodiment.

Specific implementation method three

This embodiment is a further description of the second embodiment. In this embodiment, the process of obtaining the round-trip deviation value of any auxiliary positioning point further includes:

Step 34: Return and execute step 31 to step 33 to obtain multiple round-trip deviation values, and calculate the arithmetic mean based on the multiple round-trip deviation values as the final round-trip deviation value.

The other technical features of this embodiment are exactly the same as those of the second embodiment.

Specific implementation method four

This implementation is a further description of implementation one, two or three. In this implementation, step two further includes:

Control the detection robot to walk from the end point to the initial positioning position in a position mode;

The position mode is: first accelerate to a preset upper limit speed with a set first acceleration, then walk at a constant speed with the upper limit speed, and finally decelerate with a set second acceleration until the speed reaches 0;

The initial positioning position is the position of the robot detected when the linear measurement value of the driving wheel is equal to the linear expected value of the driving wheel;

The linear expected value of the driving wheel is calculated by the linear expected value of the driven wheel. It is calculated that the linear measurement value of the driving wheel is the driving wheel displacement obtained according to the actual number of revolutions of the driving wheel.

The other technical features of this embodiment are exactly the same as those of embodiments one, two or three.

Specific implementation method five

This implementation is a further description of the fourth implementation. In this implementation, step four also includes:

Control the detection robot to move from the initial positioning position to the position to be detected in a speed mode;

The speed mode is: walking at a constant speed at the set constant speed.

The other technical features of this embodiment are exactly the same as those of embodiment 4.

Specific implementation method 6

This embodiment is a further description of the fifth embodiment. In this embodiment, the material of the driven wheel is at least one of polyurethane, polyvinyl chloride or polyamide.

The other technical features of this embodiment are exactly the same as those of embodiment five.

Specific implementation method seven

A walking and positioning system for an EMU undercarriage inspection robot according to this embodiment includes a controller 1;

The controller 1 is used to execute the walking positioning method of the fifth implementation mode.

Specific implementation method eight

This embodiment is a further description of the seventh embodiment. In this embodiment, a first encoder 2, a second encoder 3, a plurality of magnetic bodies 4 and a magnetic detection device 5 are further included.

The first encoder 2 is used to obtain the linear measurement value of the driving wheel in real time;

The second encoder 3 is used to obtain the linear measurement value of the driven wheel in real time;

A magnetic body 4, used as an auxiliary positioning point;

The magnetic detection device 5 is used to detect the magnetic body 4 and output a pulse detection signal.

The other technical features of this embodiment are exactly the same as those of embodiment seven.

Specific implementation method nine

This embodiment is a further explanation of the eighth embodiment. In this embodiment, the plurality of magnetic bodies 4 and the magnetic detection device 5 are all located on the same horizontal plane.

The other technical features of this embodiment are exactly the same as those of embodiment eight.

Specific implementation method ten

This embodiment is a further explanation of the eighth or ninth embodiment. In this embodiment, the time corresponding to the rising edge of the pulse detection signal is used as the time when the corresponding auxiliary positioning point is detected.

The other technical features of this embodiment are exactly the same as those of embodiment eight or nine.

Specific embodiments

The positioning system of the present invention is based on a detection robot for the bottom of a train, comprising a running track, a running device (a driving wheel 6, a driven wheel 7 and a servo motor driving the driving wheel 6 to rotate), a detection robot body, a necessary power supply device and a communication device. The detection robot walks on the running track through the driving wheel 6 and the driven wheel 7.

A walking positioning system for an EMU vehicle bottom detection robot of the present invention comprises:

Controller 1 (PLC may be selected) executes corresponding methods.

The first encoder 2 is drivingly connected to the driving wheel 6 and the driving wheel driving motor.

The second encoder 3 is transmission-connected with the driven wheel 7. The travel wheel comprises a driving wheel 6 and a driven wheel 7 associated therewith.

Magnetic bodies 4 are embedded in the running track at equal intervals to serve as auxiliary positioning points.

The magnetic detection device 5 is arranged at the bottom of the detection robot close to the end of the walking track, and uses the Hall effect principle to detect the magnetic body 4 arranged on the track; the installation height of the magnetic body 4 and the magnetic detection device 5 on the detection robot are consistent and in the same horizontal plane.

The present invention provides a walking and positioning method for an EMU undercarriage inspection robot, the application environment of which is the undercarriage inspection of an EMU, and the working mode is fixed as follows: the inspection robot starts from a starting point and walks to a terminal position, scanning the undercarriage of the EMU during the walking process, and after reaching the terminal, calculates and obtains at least one position to be inspected under the EMU; the inspection robot returns from the terminal, moves to the positions to be inspected in turn, stops for inspection, and returns to the starting point after all inspections are completed, and the task is completed. Specifically, the following steps are included:

S1. Before the first use, first perform self-calibration. Determine the end point of the detection robot according to the type of train to be detected (the distance from the starting point to the end point must exceed the length of the train). Record the value of the second encoder 3 when the magnetic detection device 5 senses the rising edge of the magnetic body 4 during the process of the detection robot starting from the starting point and arriving at the end point. (The magnetic detection device 5 usually outputs a low level, and outputs a high level when detecting magnetism, generating a rising edge, and generating a falling edge after leaving the magnetic body 4. The value of the second encoder 3 corresponding to the rising edge is used as a reference as the moment when the magnetic body 4 is detected. Since the magnetic body 4 itself has a certain width and the magnetic field has a certain range, there is a fixed deviation between the rising edge induced by the detection robot passing through the magnetic body 4 in the forward direction and the rising edge generated by the reverse passing through the same magnetic body 4. This is caused by the characteristics of the magnetic body 4. Different magnetic bodies 4 have different installation processes and their own characteristics, resulting in different round-trip deviations for each magnetic body 4. Therefore, calibration is required.) Starting from the starting point, the values of the second encoder 3 corresponding to the rising edge induced by the magnetic detection device 5 passing through the magnetic body 4 in sequence are _a1 , _a2 , _a3 , ...a _n . If the same magnetic body 4 generates more than one value of the second encoder 3, the first one shall prevail. The subscript value represents the serial number of the magnetic body 4 passed from the starting point. Returning from the end point, the magnetic body 4 is passed in sequence to obtain the values _bn , _bn-1 , bn _-2 , ... _b1 of the second encoder 3 corresponding to the rising edge of the magnetic detection device 5. The magnetic detection device 5 approaches the same magnetic body 4 in different directions, and there is a fixed delay deviation in the induction signal. The resulting encoder difference is _a1 - _b1 , _a2 - _b2 , _a3 - _b3 , ...a _n - _bn . The above calibration process is repeated multiple times and the arithmetic average is recorded as _δ1 , _δ2 , _δ3 , ... _δn ; the above operation is repeated for different vehicle models.

Since the detection robot mainly relies on the actual number of revolutions of the driving wheel 6 detected by the first encoder 2 for positioning during the process of walking from the starting point to the end point, even if an end point is pre-set (this end point is the expected end point), due to the slip defect of the driving wheel 6, the detection robot cannot actually reach the expected end point accurately. The detection robot first starts from the starting point and walks quickly to the actual position corresponding to the expected end point in position mode and through the first encoder 2, and an additional end point magnetic body can be set in advance behind the expected end point (from the starting point to the end point), and then the detection robot is controlled to walk to the position of the end point magnetic body in speed mode and stop. At this time, the position of the end point magnetic body is the actual end point. Since the position of the end point magnetic body does not change when the same EMU is detected, it is ensured that the starting and end point positions of the detection robot are consistent during multiple calibrations, and the consistency is intact.

S2. During use, each time the detection robot sets out to perform a task, it is ensured to start from a fixed starting point to avoid accumulating walking errors from the previous task; the task end point is fixed, and the position of the magnetic body 4 after the position mode docking position is used as a marker to ensure that the round trip is consistent;

S3. Officially start the mission, starting from the starting point, determine the end point according to the EMU model detected in this mission, the detection robot starts in the position mode, sets the value of the first encoder 2 (the expected end point), and judges whether the expected end point has been reached based on the value of the first encoder 2 fed back by the driving wheel 6. During the process, the values _x1 , _x2 , _x3 ... _xn of the second encoder 3 obtained when each magnetic body 4 is detected are recorded in sequence. After reaching the actual position of the expected end point set in the position mode, start switching the speed mode, and stop at the first end point magnetic body (actual end point) after walking to the actual position of the expected end point.

Calculate the value of the second encoder 3 corresponding to the position to be detected under the EMU Determine the value of the second encoder 3 corresponding to the first magnetic body 4 that passes after the position to be detected. Assuming x _k , determine the distance between the target position and the kth magnetic body 4 The detection robot starts from the end point and first walks in position mode to set the target position Function f is the numerical formula for converting the value of the second encoder 3 into the numerical formula of the first encoder 2. The position obtained by the conversion calculation is used as the desired initial positioning position. The controller uses the desired initial positioning position to control the driving wheel to walk. After the position mode ends, the positioning system obtains the numerical value y _k of the second encoder 3 corresponding to the last magnetic body 4 (i.e., the kth magnetic body 4) passed during the travel process. Then, according to the formula The precise position of the position to be detected is calculated, and the second encoder 3 is used to control the detection robot to walk at a low speed from the current position in speed mode, and the value of the second encoder 3 is obtained in real time. After reaching the precise position of the above-mentioned position to be detected, the speed drops to 0 and stops at the accurate position to be detected.

S4 and magnetic bodies 4 are installed on the walking track at equal intervals, the entire walking path of the detection robot is divided into multiple small blocks, the position to be detected is located at the distance from a certain magnetic body 4, and the cumulative error of the whole process is reduced to the error of the distance between every two magnetic bodies 4;

S5, the encoder data of the nearest magnetic body 4 sensed by the magnetic detection device 5 before the detection robot returns from the end point to the position to be detected is used as the determination of the magnetic body 4, so as to avoid the loss of the magnetic body 4 sensing during the walking process and the inability to accurately locate. If there is no signal of the magnetic body 4 during the process from the end point to the target position, the theoretical target position shall prevail and no correction shall be made;

S6. When the detection robot reaches the corrected position, it sends the movement completion status.

S7: After reaching the target position accurately and waiting for the detection action to be completed, repeat S3 to perform subsequent detection tasks, and return to the starting point after all are completed.

The actual position is consistent with the target's marked position when the distance difference between the actual position and the target's marked position is less than 5 mm.

In summary, the walking modes are divided into position mode and speed mode. The position mode is responsible for detecting that the robot walks quickly to an imprecise approximate position (initial positioning position), and directly writes the initial positioning position into the first encoder 2 through the controller 1. When detecting the start of the robot, the controller 1 selects the corresponding curve function through the corresponding distance and load conditions, and determines a non-specific acceleration function slope (first acceleration) to accelerate the curve within the set acceleration distance to reach the walking speed, drive the driving wheel 6 to walk, and calculate the difference between the linear measurement value of the driving wheel measured by the first encoder 2 and the initial positioning position in real time during the movement. When the distance travels to the deceleration distance (second acceleration ), select the corresponding deceleration ramp function curve, use a non-specific acceleration function ramp to reduce the driving speed, and finally when the actual position of the initial positioning position matches the target position initially determined, the driving speed drops to 0 and stops at the initial positioning position; the speed mode is responsible for correcting the positioning, the controller 1 controls the servo motor to drive the detection robot to walk at a low and uniform speed, and obtains the pulse value (driven wheel linear measurement value) fed back by the driven wheel 7 to the second encoder 3 in real time. When the pulse value (driven wheel linear measurement value) fed back by the second encoder 3 reaches the set precise position to be detected, the detection robot speed drops to 0 and stops at the current position to be detected, and the speed mode ends.

The driven wheel is made of polyurethane and is a non-powered wheel, which significantly reduces the position error caused by slipping during walking. The positioning system calculates and corrects the walking target position through a logical algorithm. The coordination of the return-to-origin proximity switch and the return-to-origin positioning mark ensures that the inspection robot starts from the same starting point every time and returns to the starting point after the task is completed.

Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the features of the various dependent claims and herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with the individual embodiments may be used in other embodiments.

Claims (10)

1. The method for positioning the walking of the detection robot at the bottom of the motor train unit is realized based on a detection robot, and the detection robot comprises a driving wheel and a driven wheel;

The method is characterized by comprising the following steps of:

step one, controlling a detection robot to walk from a starting point to an end point along a linear path, and calculating to obtain a linear expected value phi of a driven wheel corresponding to a position to be detected; acquiring a linear measurement value x _k of the acquired driven wheel when the kth auxiliary positioning point is detected;

The position to be detected is obtained by identifying the detection robot after scanning the complete motor train unit bottom;

the number of the auxiliary positioning points is n, and the n auxiliary positioning points are arranged on the straight line path at equal intervals;

The kth auxiliary positioning point is an auxiliary positioning point adjacent to the position to be detected and close to the end point side, and k is more than or equal to 1 and less than or equal to n;

The driven wheel linear expected value is driven wheel displacement obtained according to the expected number of revolutions of the driven wheel, and the driven wheel linear measured value is driven wheel displacement obtained according to the actual number of revolutions of the driven wheel;

step two, controlling the detection robot to walk from the end point to the starting point along the linear path, and acquiring a corresponding linear measurement value y _k of the driven wheel when the kth auxiliary positioning point is detected again;

Step three, calculating to obtain a correction value of the position to be detected through the following formula:

p＝φ-x_k+y_k+δ_k；

wherein delta _k is the round trip deviation value of the kth auxiliary locating point;

and fourthly, continuously controlling the detection robot to walk to the position to be detected according to the correction value of the position to be detected, and completing walking positioning of the detection robot.

2. The method for positioning the walking of the detection robot at the bottom of the motor train unit according to claim 1, wherein the process of acquiring the round trip deviation value of any auxiliary positioning point is as follows:

step three, controlling a detection robot to walk from a starting point to an end point along the linear path, and acquiring a corresponding linear measurement value a _n of the driven wheel when any auxiliary positioning point is detected;

step three, controlling the detection robot to walk from the end point to the starting point along the linear path; when any auxiliary positioning point is detected again, a corresponding linear measurement value bn of the driven wheel is obtained;

thirdly, calculating to obtain the round trip deviation value of any auxiliary locating point by the following formula:

δ_n＝a_n-b_n。

3. The method for positioning a motor train unit bottom detection robot according to claim 2, wherein the process of acquiring the round trip deviation value of any auxiliary positioning point further comprises:

And step three, returning to and executing the step three, the step one and the step three to obtain a plurality of round trip deviation values, and calculating an arithmetic average value according to the plurality of round trip deviation values to obtain a final round trip deviation value.

4. A method for positioning a motor train unit bottom detection robot as set forth in claim 1, 2 or 3, wherein the second step further comprises:

controlling the detection robot to walk from the end point to the initial positioning position in a position mode;

the position mode is as follows: firstly, accelerating to travel to a preset upper limit speed by a set first acceleration, then traveling at a constant speed by the upper limit speed, and finally decelerating to travel by a set second acceleration until the speed is 0;

the initial positioning position is the position of the detection robot when the linear measured value of the driving wheel is equal to the linear expected value of the driving wheel;

The driving wheel linear expected value is obtained through calculation of the driven wheel linear expected value phi, and the driving wheel linear measured value is the driving wheel displacement obtained according to the actual rotation number of the driving wheel.

5. The method for positioning a motor train unit bottom detection robot as set forth in claim 4, wherein the fourth step further comprises:

controlling the detection robot to walk from the initial positioning position to the position to be detected in a speed mode;

The speed mode is: walk at a constant speed at a set constant speed.

6. The method for positioning a motor train unit bottom detection robot walking as claimed in claim 5, wherein the driven wheel is made of at least one of polyurethane, polyvinyl chloride or polyamide.

7. The system for positioning the walking of the motor train unit bottom detection robot is characterized by comprising a controller (1);

the controller (1) is configured to perform the walking positioning method of claim 5.

8. A motor train unit bottom detection robot walking positioning system according to claim 7, further comprising a first encoder (2), a second encoder (3), a plurality of magnetic bodies (4) and a magnetic detection device (5);

the first encoder (2) is used for acquiring the linear measurement value of the driving wheel in real time;

the second encoder (3) is used for acquiring linear measurement values of the driven wheel in real time;

The magnetic body (4) is used as an auxiliary positioning point;

the magnetic detection device (5) is used for detecting the magnetic body (4) and outputting a pulse detection signal.

9. A train bottom detection robot walking positioning system according to claim 8, characterized in that the plurality of magnetic bodies (4) and the magnetic detection means (5) are all located on the same horizontal plane.

10. A train bottom detection robot walking positioning system according to claim 8 or 9, wherein the moment corresponding to the rising edge of the pulse detection signal is taken as the moment when the corresponding auxiliary positioning point is detected.