Tractor control method and device capable of automatically entering and exiting parking station

Abstract

The invention discloses a control method and device for a tractor capable of automatically entering and exiting a stop station. The method comprises a station entering control process and a station exiting control process. In the station entering process, the poses of the aircraft and the stopping station line are obtained firstly, then the station entering path of the aircraft is determined, and the tractor is controlled to carry the aircraft to enter the station according to the station entering path. In the departure process, firstly, the posture of front wheels of the aircraft is obtained, the wheel holding path of the tractor is determined, then the tractor is controlled to be close to and hold the front wheels of the aircraft, and finally the aircraft is dragged to leave the station. According to the method, through accurate pose acquisition and path planning, automatic control over the tractor is achieved, and the efficiency and safety of aircraft traction operation are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic driving, and in particular to a method for controlling a tractor that automatically enters and exits a parking position. Background Art

[0002] Aircraft tugs are widely used at various airports and parking platforms. In order to improve the carrying capacity and transfer capacity of airports, the trend of unmanned and intelligent aircraft transfer is becoming more and more obvious. Among them, the aircraft entering and exiting the station is an important link in aircraft transfer, and there is an urgent need for a method that can automatically control the aircraft tug to tow the aircraft in and out of the parking station. The automatic transfer of aircraft is an extension of the unmanned driving technology of commercial and passenger vehicles in conventional aircraft transfer scenarios. There are relevant technical achievements in the fields of positioning, perception, decision-making, planning, etc., but there are no targeted improvements and optimizations for specific scenarios such as entering and exiting the station.

[0003] In the case of manually driven tractors, when an aircraft enters a parking position, the tractor driver needs to visually observe the position and posture of the aircraft currently on board the tractor, and at the same time observe the position and posture of the parking line of the target parking position, adjust the tractor to basically align with the aircraft position, and make fine adjustments when entering the station. When the aircraft leaves the station, the tractor driver first needs to observe the relative position and posture of the tractor and the aircraft's front wheels, and drive the tractor forward to align with the aircraft's front wheels. The current method of manually judging the position and posture of the aircraft and the parking position relies on the operator's past experience, resulting in high labor costs. Summary of the invention

[0004] The object of the present invention is to provide a method for controlling a tractor for automatically entering and exiting a parking position, so as to realize automatic control of the tractor and automatically tow an aircraft in and out of the parking position.

[0005] In order to solve the above technical problems, the present invention provides a technical solution: a method for controlling a tractor that automatically enters and exits a parking station. In the initial state of entering the station, the tractor holds the front wheels of the aircraft tightly. The entry control process includes:

[0006] A1. Obtain the position of the aircraft relative to the tractor;

[0007] A2. Obtain the position of the parking position line relative to the tractor;

[0008] A3. Determine the position of the aircraft relative to the parking position line based on the position of the aircraft relative to the tractor and the position of the parking position line relative to the tractor;

[0009] A4. Determine the aircraft's approach path based on the aircraft's position relative to the parking station line;

[0010] A5. Determine the approaching route of the tractor according to the approaching route of the aircraft;

[0011] A6. Control the tractor to bring the aircraft into the station according to the tractor's entry path;

[0012] At the start of the departure, the tractor is separated from the front wheels of the aircraft. The departure control process includes:

[0013] B1. Obtain the position of the aircraft's front wheels relative to the tractor;

[0014] B2. Determine the wheel holding path of the tractor according to the position of the aircraft's front wheels relative to the tractor;

[0015] B3. Control the tractor to approach the front wheels of the aircraft and complete the wheel lock according to the wheel lock path of the tractor;

[0016] B4. Tow the aircraft out of the station.

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

[0018] A101. Obtain the position of the aircraft's rear wheels relative to the tractor;

[0019] A102. Determine the position of the aircraft relative to the tractor based on the position of the aircraft's rear wheels relative to the tractor.

[0020] According to the above scheme, the parking position line includes a long line and a short line perpendicular to each other, and the position and posture of the parking position line includes the position coordinates and attitude angle of the parking position line;

[0021] Step A2 includes:

[0022] A201. Obtain 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;

[0023] A202. The position coordinates of the intersection of the long line and the short line relative to the tractor are used as the position coordinates of the parking position line relative to the tractor; the attitude angle of the long line relative to the tractor is used as the attitude angle of the parking position line relative to the tractor.

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

[0025] A501. Determine the position and posture of the tractor at any moment according to the position and posture of the aircraft at the moment before the moment;

[0026] A502. Determine the path for the tractor to enter the station based on the position of the tractor at each moment.

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

[0028] B101. Obtain the rough position of the aircraft's front wheels relative to the tractor;

[0029] B102. According to the rough position of the aircraft's front wheels relative to the towing vehicle, control the towing vehicle to approach the aircraft's front wheels;

[0030] B103. Obtain the position of the aircraft's front wheels relative to the tractor.

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

[0032] B1031a, obtain three-dimensional point cloud data of the aircraft front wheel surface through laser radar;

[0033] B1032a. Fitting the position and posture parameters of the front wheels of the aircraft according to the three-dimensional point cloud data of the surface of the front wheels of the aircraft to obtain the position and posture of the front wheels of the aircraft relative to the tractor.

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

[0035] B1031b, obtaining a two-dimensional image of the surface of the front wheel of the aircraft by means of a camera;

[0036] B1032b. Obtain edge curves on the right sides of the front wheel of the aircraft by performing edge detection on the two-dimensional image of the surface of the front wheel of the aircraft;

[0037] B1033b. Determine the attitude angle of the aircraft's front wheels relative to the tractor based on the difference in curvature of the edge curves on the right sides of the aircraft's front wheels;

[0038] B1034b, determine the position coordinates of the front wheels of the aircraft relative to the tractor according to the proportion and position of the front wheels of the aircraft in the two-dimensional image;

[0039] B1035b. Combine the attitude angle and position coordinates of the aircraft's front wheels relative to the tractor to obtain the position and attitude of the aircraft's front wheels relative to the tractor.

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

[0041] B1031c, obtain the three-dimensional point cloud data of the aircraft front wheel surface through laser radar;

[0042] B1032c, obtaining a two-dimensional image of the surface of the front wheel of the aircraft by means of a camera;

[0043] B1033c, fusing the three-dimensional point cloud data and the two-dimensional image of the surface of the front wheel of the aircraft to obtain fused data;

[0044] B1034c. Use the preset ideal tire surface model to fit the fusion data and obtain the position 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 a parking station, comprising an entry control module and an exit control module;

[0046] The station entry control module is used to obtain the position and posture of the aircraft relative to the tractor; obtain the position and posture of the parking station line relative to the tractor; determine the position and posture of the aircraft relative to the parking station line according to the position and posture of the aircraft relative to the tractor and the position and posture of the parking station line relative to the tractor; determine the station entry path of the aircraft according to the position and posture of the aircraft relative to the parking station line; determine the station entry path of the tractor according to the station entry path of the aircraft; and control the tractor to enter the station with the aircraft according to the station entry path of the tractor;

[0047] The outbound control module is used to obtain the position of the aircraft's front wheels relative to the tractor; determine the tractor's wheel-holding path according to the position of the aircraft's front wheels relative to the tractor; control the tractor to approach the aircraft's front wheels and complete the wheel-holding according to the tractor's wheel-holding path; and tow the aircraft outbound.

[0048] The present invention also provides a tractor, comprising:

[0049] A sensor module, used to obtain sensor data of each wheel and parking position line of the aircraft through measurement;

[0050] The above-mentioned tractor control device for automatically entering and exiting the parking position is used to control the tractor to carry the aircraft into the station or tow the aircraft out of the station according to the sensor data of the aircraft wheels and the parking position line.

[0051] The beneficial effect of the present invention is that by identifying the position and posture of key targets including aircraft wheels and parking position lines, the aircraft path and the corresponding tractor path when the aircraft enters / leaves the station are constructed, thereby realizing the path control of the tractor when the aircraft enters / leaves the station. The method provided by the present invention realizes automatic identification and automatic control. Compared with the existing manual identification and control, the present invention avoids the problems of parking position deviation, incorrect parking posture, and repeated adjustment caused by differences in driving skills of tractor drivers, and improves the operating efficiency while reducing the level requirements of operating personnel and reducing labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a flow chart of automatic entry and exit of a parking station according to an embodiment of the present invention;

[0053] Figure 2 is a schematic diagram of the relative positions of a tractor and a loaded aircraft according to an embodiment of the present invention;

[0054] Figure 3 is a schematic diagram of identifying the position and posture of a parking station line according to an embodiment of the present invention;

[0055] Figure 4 is a schematic diagram of an embodiment of the present invention wherein a loaded aircraft is aligned with a parking stand line;

[0056] Figure 5It is a schematic diagram of identifying the position and posture of the front wheels of an aircraft according to an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0058] See also Figure 1 This embodiment provides a method for controlling a tractor that automatically enters and exits a parking position, comprising the following steps:

[0059] a. Automatic entry:

[0060] Step a.1, measuring the posture of the loaded aircraft. Since the tractor holds the front wheels of the aircraft tightly when carrying a load, the position and posture of the rear wheels of the loaded aircraft can be calculated by measuring the posture of the rear wheels of the loaded aircraft using the on-board laser radar and camera. Figure 2 The motion of the aircraft and tractor on the airport ground can be regarded as plane motion. Under certain conditions, the tractor and aircraft can be considered as rigid bodies. Three variables are required to characterize the position and attitude of a rigid body in plane motion: two position variables and one attitude (direction) variable. Three parameters are required to determine the position and attitude of the aircraft in the tractor coordinate system. During the towing process of the aircraft, the front wheels of the aircraft are lifted up and can rotate, so the relative attitude angle between the aircraft and the tractor is variable. The on-board sensors include cameras and laser radars. In order to identify the state of the loaded aircraft, these two types of data must be processed separately first, the aircraft tires in the field of view must be detected and preliminarily located, and then the two sets of information obtained must be compared and analyzed to improve the reliability of the detection results. Finally, the two-dimensional image and three-dimensional point cloud of the small area where the tire is detected are fused to accurately locate the position of the tire in the tractor coordinate system.

[0061] Step a.2, measure the position and posture of the parking position line. Use the on-board laser radar and camera to measure the position and posture of the target parking position line relative to the tractor. Figure 3 The parking position line image obtained by the camera is processed to extract the long and short straight lines, calculate the image coordinates of their intersection, and obtain the direction of the intersection. The intersection of the long and short straight lines is extracted from the target reflection intensity image obtained by the laser radar to obtain the corresponding distance information. Combining the intersection direction obtained by the camera and the distance information obtained by the laser radar, the position coordinates and attitude direction of the parking position line can be obtained.

[0062] Step a.3, calculate the position and posture of the aircraft relative to the parking position line. Calculate the position and posture of the aircraft relative to the target parking position line based on the measurement results of the first two steps, which will serve as the basis for calculating the approach path. Figure 4 As shown, the relative posture transformation between the tractor and the aircraft is solved, which mainly includes relative attitude and relative position. Three parameters are required to determine the relative posture of the aircraft and the parking position line.

[0063] Step a.4, calculate the approach path. Plan the aircraft's approach path based on the relative posture calculated in the previous step, and then generate the tractor's approach path based on the aircraft's approach path. The tractor carries the aircraft into the station along the predetermined path and aligns with the parking station line. When the planner performs trajectory planning, the center of motion considered is the aircraft. The tractor's path can be inferred based on the aircraft's discrete path, and the tractor's current posture can be calculated based on the aircraft's previous posture and current posture. Finally, the tractor is controlled to carry the aircraft into the station based on the inversely calculated tractor path.

[0064] b. Automatic exit:

[0065] Step b.1, measure the position and posture of the front wheels of the outbound aircraft. Use the on-board laser radar and camera to measure the position and posture of the front wheels of the outbound aircraft. When the tractor approaches the outbound aircraft, the distance between the aircraft and the tractor is further shortened, and the on-board sensor on the tractor can measure the position and posture of the aircraft wheels more accurately. Three parameters are required to determine the position and posture of the aircraft's front wheels in the tractor coordinate system, such as Figure 5 As shown. When the front wheel is aligned, the attitude angle of the front wheel is exactly the same as the attitude angle of the aircraft. First, the front wheel posture measurement based on the three-dimensional point cloud of the laser radar can be used to establish a three-dimensional model of the tire surface. The three posture parameters of the tire are taken as unknowns, and the three-dimensional point cloud data of the laser radar is used for fitting to obtain the posture of the tire. Secondly, the front wheel posture 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 performing edge detection on the tire image, the left and right tire edge curves are obtained. These two curves should be symmetrical when the tire attitude angle is zero. When the curvature of the two curves is different, the attitude angle can be measured. On this basis, the two-dimensional image and three-dimensional point cloud of the tire area can also be fused, and the fused data can be fitted with the ideal tire surface model to obtain the posture of the tire.

[0066] Step b.2, calculate the position and attitude of the front wheel of the aircraft relative to the tractor. Based on the measurement results of the previous step, calculate the position and attitude of the front wheel of the aircraft relative to the tractor, which will serve as the basis for calculating the wheel holding path in the next step.

[0067] Step b.3, calculate the wheel-holding path, hold the wheels and tow out of the station. Based on the relative position calculated in the previous step, calculate the path for the tractor to approach the aircraft and hold the wheels. According to the path, control the tractor to approach the front wheels of the aircraft and complete the wheel holding, and tow the aircraft out of the parking station.

[0068] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for controlling a tractor that automatically enters and exits a parking position, characterized in that: At the start of the pit stop, the tractor holds the front wheels of the aircraft tightly. The pit stop control process includes: A1. Obtain the position of the aircraft relative to the tractor; A2. Obtain the position of the parking position line relative to the tractor; A3. Determine the position of the aircraft relative to the parking position line based on the position of the aircraft relative to the tractor and the position of the parking position line relative to the tractor; A4. Determine the aircraft's approach path based on the aircraft's position relative to the parking station line; A5. Determine the approaching route of the tractor according to the approaching route of the aircraft; A6. Control the tractor to bring the aircraft into the station according to the tractor's entry path; At the start of the departure, the tractor is separated from the front wheels of the aircraft. The departure control process includes: B1. Obtain the position of the aircraft's front wheels relative to the tractor; B2. Determine the wheel holding path of the tractor according to the position of the aircraft's front wheels relative to the tractor; B3. Control the tractor to approach the front wheels of the aircraft and complete the wheel lock according to the wheel lock path of the tractor; B4. Tow the aircraft out of the station.

2. The method for controlling a tractor that automatically enters and exits a parking position according to claim 1, characterized in that: Step A1 includes: A101. Obtain the position of the aircraft's rear wheels relative to the tractor; A102. Determine the position of the aircraft relative to the tractor based on the position of the aircraft's rear wheels relative to the tractor.

3. The method for controlling a tractor that automatically enters and exits a parking position according to claim 1, characterized in that: The parking position line includes a long line and a short line perpendicular to each other, and the position and posture of the parking position line includes the position coordinates and attitude angle of the parking position line; Step A2 includes: A201. Obtain 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. The position coordinates of the intersection of the long line and the short line relative to the tractor are used as the position coordinates of the parking position line relative to the tractor; the attitude angle of the long line relative to the tractor is used as the attitude angle of the parking position line relative to the tractor.

4. The method for controlling a tractor that automatically enters and exits a parking position according to claim 1, characterized in that: Step A5 includes: A501. Determine the position and posture of the tractor at any moment according to the position and posture of the aircraft at the moment before the moment; A502. Determine the path for the tractor to enter the station based on the position of the tractor at each moment.

5. The method for controlling a tractor that automatically enters and exits a parking position according to claim 1, characterized in that: Step B1 includes: B101. Obtain the rough position of the aircraft's front wheels relative to the tractor; B102. According to the rough position of the aircraft's front wheels relative to the towing vehicle, control the towing vehicle to approach the aircraft's front wheels; B103. Obtain the position of the aircraft's front wheels relative to the tractor.

6. The method for controlling a tractor that automatically enters and exits a parking position according to claim 5, characterized in that: Step B103 includes: B1031a, obtain three-dimensional point cloud data of the aircraft front wheel surface through laser radar; B1032a. Fitting the position and posture parameters of the front wheels of the aircraft according to the three-dimensional point cloud data of the surface of the front wheels of the aircraft to obtain the position and posture of the front wheels of the aircraft relative to the tractor.

7. The method for controlling a tractor that automatically enters and exits a parking position according to claim 5, characterized in that: Step B103 includes: B1031b, obtaining a two-dimensional image of the surface of the front wheel of the aircraft by means of a camera; B1032b. Obtain edge curves on the right sides of the front wheel of the aircraft by performing edge detection on the two-dimensional image of the surface of the front wheel of the aircraft; B1033b. Determine the attitude angle of the aircraft's front wheels relative to the tractor based on the difference in curvature of the edge curves on the right sides of the aircraft's front wheels; B1034b, determine the position coordinates of the front wheels of the aircraft relative to the tractor according to the proportion and position of the front wheels of the aircraft in the two-dimensional image; B1035b. Combine the attitude angle and position coordinates of the aircraft's front wheels relative to the tractor to obtain the position and attitude of the aircraft's front wheels relative to the tractor.

8. The method for controlling a tractor that automatically enters and exits a parking position according to claim 1, characterized in that: Step B103 includes: B1031c, obtain the three-dimensional point cloud data of the aircraft front wheel surface through laser radar; B1032c, obtaining a two-dimensional image of the surface of the front wheel of the aircraft by means of a camera; B1033c, fusing the three-dimensional point cloud data and the two-dimensional image of the surface of the front wheel of the aircraft to obtain fused data; B1034c. Use the preset ideal tire surface model to fit the fusion data and obtain the position of the aircraft's front wheel relative to the tractor.

9. A tractor control device for automatically entering and exiting a parking position, characterized in that: It includes an entry control module and an exit control module; The station entry control module is used to obtain the position and posture of the aircraft relative to the tractor; obtain the position and posture of the parking position line relative to the tractor; determine the position and posture of the aircraft relative to the parking position line according to the position and posture of the aircraft relative to the tractor and the position and posture of the parking position line relative to the tractor; Determine the aircraft's approach path based on the aircraft's position relative to the parking station line; determine the tractor's approach path based on the aircraft's approach path; and control the tractor carrying the aircraft into the station based on the tractor's approach path. The outbound control module is used to obtain the position of the aircraft's front wheels relative to the tractor; determine the tractor's wheel-holding path according to the position of the aircraft's front wheels relative to the tractor; control the tractor to approach the aircraft's front wheels and complete the wheel-holding according to the tractor's wheel-holding path; and tow the aircraft outbound.

10. A tractor, characterized in that: include: A sensor module, used to obtain sensor data of each wheel and parking position line of the aircraft through measurement; The tractor control device for automatically entering and exiting a parking space as described in claim 9 is used to control the tractor to carry the aircraft into the space or tow the aircraft out of the space based on the sensor data of the aircraft wheels and the parking space line.

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