A method and device for controlling a tractor to automatically enter and exit a parking station

Abstract

The application discloses a kind of automatic entry and exit parking station's tractor control method and device, the method includes two control processes of entry and exit.The entry process, first obtain the pose of aircraft and parking station line, then determine the entry path of aircraft, and control the tractor with load aircraft entry accordingly.In the exit process, first obtain the pose of aircraft front wheel, determine the tractor's wheel path, then control the tractor to approach aircraft front wheel and hold tightly, finally, the aircraft is pulled out of station.The method realizes the automation control of tractor through accurate pose acquisition and path planning, improves the efficiency and safety of aircraft traction operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automatic driving, in particular to a control method of a tractor for automatically entering and exiting a parking station. BACKGROUND

[0002] The aircraft tractor is widely used in various airports and parking platforms. In order to improve the carrying capacity and transfer capacity of the airport, the unmanned and intelligent trend of aircraft transfer is becoming more and more obvious. Among them, the aircraft entering and exiting the station is an important link in the aircraft transfer, and an automatic control method of the aircraft tractor for pulling the aircraft into and out of the parking station is urgently needed. The automatic transfer of the aircraft is an extension of the unmanned driving technology of commercial and passenger vehicles in the conventional aircraft transfer scene, and there are related technical achievements in the fields of positioning, perception, decision-making, planning, etc., but there is no targeted improvement and optimization for specific scenes such as entering and exiting the station.

[0003] In the case of manually driving the tractor, when the aircraft enters the parking station, the tractor driver needs to visually observe the position and attitude of the current loaded aircraft of the tractor, and at the same time observe the position and attitude of the station line of the target parking station, adjust the tractor to basically align with the aircraft station, and fine-tune when entering the station. When the aircraft exits the station, the tractor driver first needs to observe the relative position and attitude of the tractor and the front wheel of the aircraft, and drive the tractor to align with the front wheel of the aircraft. The current method of manually judging the position and attitude of the aircraft and the parking station relies on the experience of the operator, resulting in high labor cost. SUMMARY

[0004] The purpose of the present application is to provide a control method of a tractor for automatically entering and exiting a parking station, so as to realize the automatic control of the tractor and automatically pull the aircraft into and out of the parking station.

[0005] To solve the above technical problems, the present application provides a technical solution: a control method of a tractor for automatically entering and exiting a parking station, the starting state of entering the station is that the tractor holds the front wheel of the aircraft, and the entering control process includes:

[0006] A1, obtaining the position and attitude of the aircraft relative to the tractor;

[0007] A2, obtaining the position and attitude of the station line relative to the tractor;

[0008] A3, determining the position and attitude of the aircraft relative to the station line according to the position and attitude of the aircraft relative to the tractor and the position and attitude of the station line relative to the tractor;

[0009] A4, determining the entering path of the aircraft according to the position and attitude of the aircraft relative to the station line;

[0010] A5, determining the entering path of the tractor according to the entering path of the aircraft;

[0011] A6, controlling the towing vehicle to enter the station according to the entering path of the towing vehicle;

[0012] The initial state of the exiting process is that the towing vehicle is separated from the front wheel of the airplane, and the exiting control process comprises:

[0013] B1, acquiring the pose of the front wheel of the airplane relative to the towing vehicle;

[0014] B2, determining the wheel-holding path of the towing vehicle according to the pose of the front wheel of the airplane relative to the towing vehicle;

[0015] B3, controlling the towing vehicle to approach the front wheel of the airplane and complete the wheel holding according to the wheel-holding path of the towing vehicle;

[0016] B4, towing the airplane to exit.

[0017] According to the above scheme, step A1 comprises:

[0018] A101, acquiring the pose of the rear wheel of the airplane relative to the towing vehicle;

[0019] A102, determining the pose of the airplane relative to the towing vehicle according to the pose of the rear wheel of the airplane relative to the towing vehicle.

[0020] According to the above scheme, the parking station position line comprises a long line and a short line which are perpendicular to each other, and the pose of the parking station position line comprises the position coordinates and the attitude angle of the parking station position line;

[0021] Step A2 comprises:

[0022] A201, acquiring the position coordinates of each point in the long line and the short line relative to the towing vehicle, and the attitude angle of the long line relative to the towing vehicle;

[0023] A202, taking the position coordinates of the intersection of the long line and the short line relative to the towing vehicle as the position coordinates of the parking station position line relative to the towing vehicle, and taking the attitude angle of the long line relative to the towing vehicle as the attitude angle of the parking station position line relative to the towing vehicle.

[0024] According to the above scheme, step A5 comprises:

[0025] A501, determining the pose of the towing vehicle at any time according to the pose of the airplane at the time and the pose of the airplane at the previous time of the time;

[0026] A502, determining the entering path of the towing vehicle according to the poses of the towing vehicle at each time.

[0027] According to the above scheme, step B1 comprises:

[0028] B101, acquiring the rough pose of the front wheel of the airplane relative to the towing vehicle;

[0029] B102. Based on the approximate position of the aircraft's nose wheel relative to the towing vehicle, control the towing vehicle to move closer to the aircraft's nose wheel;

[0030] B103. Obtain the position and orientation of the aircraft's nose wheel relative to the towing vehicle.

[0031] According to the above scheme, step B103 includes:

[0032] B1031a. Acquire three-dimensional point cloud data of the aircraft's nose wheel surface using lidar;

[0033] B1032a. Fit the pose parameters of the aircraft's nose wheel based on the three-dimensional point cloud data of the aircraft's nose wheel surface to obtain the pose of the aircraft's nose wheel relative to the tractor.

[0034] According to the above scheme, step B103 includes:

[0035] B1031b. Acquire a two-dimensional image of the surface of the aircraft's nose wheel using a camera;

[0036] B1032b: By performing edge detection on a two-dimensional image of the aircraft's nose wheel surface, the edge curves on the right sides of the aircraft's nose wheel are obtained;

[0037] B1033b. Determine the attitude angle of the aircraft's nose wheel relative to the tractor based on the curvature difference of the edge curves on both sides of the aircraft's nose wheel.

[0038] B1034b. Determine the position coordinates of the aircraft's nose wheel relative to the tractor based on the proportion and position of the nose wheel in the two-dimensional image.

[0039] B1035b. By combining the attitude angle and position coordinates of the aircraft's nose wheel relative to the towing vehicle, the attitude of the aircraft's nose wheel relative to the towing vehicle is obtained.

[0040] According to the above scheme, step B103 includes:

[0041] B1031c: Acquire three-dimensional point cloud data of the aircraft's nose wheel surface using lidar;

[0042] B1032c: Acquire two-dimensional images of the surface of the aircraft's nose wheel using a camera;

[0043] B1033c: The three-dimensional point cloud data and two-dimensional image of the aircraft's nose wheel surface are fused to obtain fused data;

[0044] B1034c: The fused data is fitted using a preset ideal tire surface model to obtain the pose of the aircraft's front wheel relative to the tractor.

[0045] The present invention also provides a tractor control device for automatically entering and exiting parking positions, including an entry control module and an exit control module;

[0046] The in-station control module is configured to acquire the pose of the aircraft relative to the tractor, acquire the pose of the parking station line relative to the tractor, determine the pose of the aircraft relative to the parking station line according to the pose of the aircraft relative to the tractor and the pose of the parking station line relative to the tractor, determine the in-station path of the aircraft according to the pose of the aircraft relative to the parking station line, determine the in-station path of the tractor according to the in-station path of the aircraft, and control the tractor to bring the aircraft into the station according to the in-station path of the tractor.

[0047] The out-station control module is configured to acquire the pose of the front wheel of the aircraft relative to the tractor, determine the wheel-holding path of the tractor according to the pose of the front wheel of the aircraft relative to the tractor, control the tractor to approach the front wheel of the aircraft and complete wheel holding according to the wheel-holding path of the tractor, and tow the aircraft out of the station.

[0048] The present application also provides a tractor comprising:

[0049] The sensing module is configured to acquire sensing data of the wheels of the aircraft and the parking station line by measurement.

[0050] The tractor control device for automatic in-out of the parking station described above is configured to control the tractor to bring the aircraft into the station or tow the aircraft out of the station according to the sensing data of the wheels of the aircraft and the parking station line.

[0051] The present application has the beneficial effects that by recognizing the poses of the key targets including the wheels of the aircraft and the parking station line, the aircraft path and the corresponding tractor path during the in-out of the station are constructed, and the path control of the tractor during the in-out of the station is realized. The method provided by the present application realizes automatic recognition and automatic control, and compared with the existing manual recognition and control, the present application avoids the problems of position deviation, incorrect attitude, and the need for repeated adjustment caused by the difference in driving level of the tractor driver, reduces the level requirement of the operating personnel and the labor cost, and improves the operating efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 is a flowchart of automatic in-out of the parking station according to an embodiment of the present application;

[0053] Figure 2 is a schematic diagram of the relative poses of the tractor and the aircraft with load according to an embodiment of the present application;

[0054] Figure 3 is a schematic diagram of recognizing the pose of the parking station line according to an embodiment of the present application;

[0055] Figure 4 is a schematic diagram of aligning the aircraft with load and the parking station line according to an embodiment of the present application;

[0056] Figure 5This is a schematic diagram illustrating the identification of the nose wheel position of an aircraft according to an embodiment of the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0058] See Figure 1 This embodiment provides a method for controlling a tractor to automatically enter and exit a parking position, including the following steps:

[0059] a. Automatic entry:

[0060] Step a.1: Measure the attitude of the aircraft as it enters the station with the load. Since the towing vehicle grips the aircraft's nose wheels while carrying the load, the position and attitude of the aircraft relative to the towing vehicle can be calculated by measuring the attitude of the rear wheels using the vehicle-mounted lidar and camera. For example... Figure 2 The motion of the aircraft and towing vehicle on the airport ground can be considered planar motion, and under certain conditions, the towing vehicle and aircraft can be considered rigid bodies. A rigid body in planar motion requires three variables to characterize its position and attitude: two position variables and one attitude (direction) variable. Determining the aircraft's position and attitude in the towing vehicle's coordinate system requires three parameters. During towing, the aircraft's nose wheel is lifted and can rotate, therefore the relative attitude angle between the aircraft and the towing vehicle is variable. The onboard sensors include cameras and lidar. To identify the state of the towed aircraft, these two types of data must first be processed separately to detect and initially locate the aircraft tires within the field of view. Then, comparing and analyzing the two sets of information can improve the reliability of the detection results. Finally, fusing the two-dimensional image and three-dimensional point cloud of the small area where the tires were detected allows for precise positioning of the tires in the towing vehicle's coordinate system.

[0061] Step a.2, measure the position and attitude of the parking station line. Use the vehicle-mounted lidar and camera to measure the position and attitude of the target parking station line relative to the tractor. For example... Figure 3 The image of the parking position line obtained by the camera is processed to extract two straight lines of different lengths, and the image coordinates of their intersection point are calculated to obtain the direction of the intersection point. The intersection point of the two straight lines of different lengths is also extracted from the target reflection intensity image obtained by the lidar, and the corresponding distance information is obtained. Combining the intersection point direction obtained by the camera and the distance information obtained by the lidar, the position coordinates and orientation of the parking position line can be obtained.

[0062] Step a.3, calculate the pose of the aircraft relative to the parking line. According to the measurement results of the previous two steps, the pose of the aircraft relative to the target parking line is calculated as the basis for calculating the path into the parking position. As shown in FIG. 3, the relative pose transformation between the tractor and the aircraft is solved, mainly including the relative attitude and the relative position. Three parameters are needed to determine the relative pose of the aircraft and the parking line. Figure 4

[0063] Step a.4, calculate the path into the parking position. According to the relative pose calculated in the previous step, the path into the parking position of the aircraft is planned, and then the path into the parking position of the tractor is generated according to the path into the parking position of the aircraft. The tractor brings the loaded aircraft into the parking position along the predetermined path and aligns with the parking line. When planning the trajectory, the planner considers the motion center to be the aircraft. The path of the tractor can be derived from the discrete path of the aircraft, and the current pose of the tractor can be calculated according to the previous pose and the current pose of the aircraft. Finally, the path of the tractor is controlled to bring the loaded aircraft into the parking position according to the derived path.

[0064] b. Automatic departure:

[0065] Step b.1, measure the pose of the front wheel of the aircraft departing. The pose of the front wheel of the aircraft departing is measured by the vehicle-mounted laser radar and camera. When the tractor approaches the aircraft departing, the distance between the aircraft and the tractor is further shortened, and the vehicle-mounted sensor on the tractor can more accurately measure the pose of the aircraft wheel. As shown in FIG. 4, three parameters are needed to determine the position and attitude of the front wheel of the aircraft in the coordinate system of the tractor. In the case of front wheel alignment, the attitude angle of the front wheel is completely consistent with the attitude angle of the aircraft. First, the three-dimensional model of the tire surface can be established based on the front wheel pose measurement of the laser radar three-dimensional point cloud, and the three pose parameters of the tire are taken as unknowns to fit the three-dimensional point cloud data of the laser radar to obtain the pose of the tire. Second, the front wheel pose measurement based on the high-definition image of the camera can be used. The camera can obtain a two-dimensional image of the tire surface. By edge detection on the tire image, two tire edge curves are obtained. When the two curves are symmetric, the attitude angle can be measured when there is a difference in the curvature of the two curves. On this basis, the two-dimensional image and three-dimensional point cloud of the tire region can also be fused and processed, and the ideal tire surface model is used to fit the fused data to obtain the pose of the tire. Figure 5 Step b.2, calculate the pose of the front wheel of the aircraft relative to the tractor. According to the measurement results of the previous step, the position and attitude of the front wheel of the aircraft relative to the tractor are calculated as the basis for calculating the wheel holding path in the next step.

[0066]

[0067] ​​Step b.3, calculate the path of embracing the wheel, embrace the wheel and pull out the station. According to the relative position calculated in the last step, the path of the towing vehicle approaching the aircraft and embracing the wheel is calculated, and the towing vehicle is controlled according to the path to approach the front wheel of the aircraft and complete the wheel embrace, and pull the aircraft out of the parking station.

[0068] The above only describes the embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, which is made by using the content of the specification and drawings of the present application, is also included in the patent protection scope of the present application.

Claims

1. A method of controlling a tractor to automatically enter and exit a parking stall, the method comprising: In the starting state of entering the station, the tractor holds the front wheel of the aircraft, and the entering station control process includes: A1, obtaining the pose of the aircraft relative to the tractor; A2, obtaining the pose of the parking station line relative to the tractor; A3, determining the pose of the aircraft relative to the parking station line according to the pose of the aircraft relative to the tractor and the pose of the parking station line relative to the tractor; A4, determining the entering station path of the aircraft according to the pose of the aircraft relative to the parking station line; A5, determining the entering station path of the tractor according to the entering station path of the aircraft; A6, controlling the tractor to enter the station with the loaded aircraft according to the entering station path of the tractor. In the starting state of leaving the station, the tractor is separated from the front wheel of the aircraft, and the leaving station control process includes: B1, obtaining the pose of the front wheel of the aircraft relative to the tractor; B2, determining the wheel holding path of the tractor according to the pose of the front wheel of the aircraft relative to the tractor; B3, controlling the tractor to approach the front wheel of the aircraft and complete the wheel holding according to the wheel holding path of the tractor; B4, pulling the aircraft to leave the station.

2. The method of claim 1, wherein, Step A1 includes: A101, obtaining the pose of the rear wheel of the aircraft relative to the tractor; A102, determining the pose of the aircraft relative to the tractor according to the pose of the rear wheel of the aircraft relative to the tractor.

3. The method of claim 1, wherein, The parking station line includes a long line and a short line perpendicular to each other, and the pose of the parking station line includes the position coordinates and the attitude angle of the parking station line; Step A2 includes: A201, obtaining the position coordinates of each point in the long line and the short line relative to the tractor, and the attitude angle of the long line relative to the tractor; A202, taking the position coordinates of the intersection of the long line and the short line relative to the tractor as the position coordinates of the parking station line relative to the tractor, and taking the attitude angle of the long line relative to the tractor as the attitude angle of the parking station line relative to the tractor.

4. The method of claim 1, wherein, Step A5 includes: A501, determining the pose of the tractor at any time according to the pose of the aircraft at that time and the pose of the aircraft at the previous time of that time; A502, determining the entering station path of the tractor according to the pose of the tractor at each time.

5. The method of claim 1, wherein, Step B1 includes: B101, obtaining the rough pose of the front wheel of the aircraft relative to the tractor; B102, controlling the tractor to approach the front wheel of the aircraft according to the rough pose of the front wheel of the aircraft relative to the tractor; B103, obtaining the pose of the front wheel of the aircraft relative to the tractor.

6. The method of claim 5, wherein, Step B103 includes: B1031a, obtaining three-dimensional point cloud data of the surface of the front wheel of the aircraft through laser radar; B1032a, fitting the pose parameters of the front wheel of the aircraft according to the three-dimensional point cloud data of the surface of the front wheel of the aircraft to obtain the pose of the front wheel of the aircraft relative to the tractor.

7. The method of claim 5, wherein, Step B103 includes: B1031b, obtaining two-dimensional images of the surface of the front wheel of the aircraft through a camera; B1032b, obtaining the edge curves of the right two sides of the front wheel of the aircraft by edge detection on the two-dimensional images of the surface of the front wheel of the aircraft; B1033b, determining the attitude angle of the front wheel of the aircraft relative to the tractor according to the curvature difference of the edge curves of the right two sides of the front wheel of the aircraft; B1034b, determining the position coordinates of the front wheel of the aircraft relative to the tractor according to the proportion and position of the front wheel of the aircraft in the two-dimensional images. B1035b, combine the attitude angle and position coordinates of the aircraft front wheel relative to the tractor to obtain the pose of the aircraft front wheel relative to the tractor.

8. The method of claim 1, wherein, Step B103 includes: B1031c, obtain three-dimensional point cloud data of the aircraft front wheel surface through laser radar; B1032c, obtain two-dimensional images of the aircraft front wheel surface through a camera; B1033c, fuse the three-dimensional point cloud data and the two-dimensional images of the aircraft front wheel surface to obtain fused data; B1034c, fit the fused data with a preset ideal tire surface model to obtain the pose of the aircraft front wheel relative to the tractor.

9. A tractor control device for automatic entry into and exit from a parking station, characterized by It comprises an entry control module and an exit control module. The entry control module is used to obtain the pose of the aircraft relative to the tractor; obtain the pose of the parking station line relative to the tractor; determine the pose of the aircraft relative to the parking station line according to the pose of the aircraft relative to the tractor and the pose of the parking station line relative to the tractor; According to the pose of the aircraft relative to the parking station line, determine the entry path of the aircraft; according to the entry path of the aircraft, determine the entry path of the tractor; according to the entry path of the tractor, control the tractor to enter the station with the loaded aircraft; The exit control module is used to obtain the pose of the aircraft front wheel relative to the tractor; determine the wheel holding path of the tractor according to the pose of the aircraft front wheel relative to the tractor; control the tractor to approach the aircraft front wheel and complete the wheel holding according to the wheel holding path of the tractor; tow the aircraft out of the station.

10. A towing vehicle characterized in that It comprises: A sensing module is used to obtain sensing data of each wheel of the aircraft and the parking station line by measurement; The automatic entry and exit parking station tractor control device of claim 9 is used to control the tractor to enter the station with the loaded aircraft or tow the aircraft out of the station according to the sensing data of each wheel of the aircraft and the parking station line.

Images