Milling machine leveling zero position automatic calibration system and method

Abstract

The invention provides an automatic leveling zero calibration system for a milling machine. The automatic leveling zero calibration system comprises a GNSS (Global Navigation Satellite System) antenna, a multi-line laser radar, a controller, a PID (Proportion Integration Differentiation) regulator, a database and an air blower which are arranged on a vehicle body, granular sundries are cleaned through an air blower, the actual milling depth of the current position is measured through a multi-line laser radar, latitude and longitude coordinates of the measured position are obtained through a GNSS antenna on a milling machine, and the preset milling depth of the current position is obtained in a database. The preset milling depth is compared with the measured actual milling depth to obtain a current milling leveling error value, and the error is automatically eliminated through a PID regulator, so that uninterrupted construction and leveling automatic calibration are realized; construction does not need to be suspended, measurement and calibration are conducted by workers, calibration precision is high, and the construction progress is not affected; under the scene that the milled road surface has fall, dynamic automatic calibration can be achieved, better milling flatness can be achieved, and the construction time is shortened.

Description

Technical Field

[0001] The invention relates to a system and method for automatically calibrating a leveling zero position of a milling machine, and belongs to the technical field of road construction machinery and automatic control. Background Art

[0002] With the continuous improvement of road maintenance construction standards and increasingly stringent construction period requirements, high-quality, efficient and intelligent milling construction has become a new trend in the industry. Traditional milling machine leveling zero calibration methods mostly rely on manual operation, which has problems such as low calibration accuracy, long time consumption, construction interruption, and susceptibility to human factors and terrain factors. It is difficult to meet the high-precision requirements of modern road construction. Summary of the invention

[0003] The purpose of the present invention is to provide a system and method for automatically calibrating the zero position of a milling machine, which can achieve accurate and rapid calibration of the zero position of the milling machine by integrating laser ranging and data processing, thereby improving the quality and efficiency of milling construction.

[0004] In order to achieve the above objectives / solve the above technical problems, the present invention is implemented by adopting the following technical solutions.

[0005] In a first aspect, the present invention provides a milling machine leveling zero position automatic calibration system, comprising: a database, a GNSS antenna mounted on a vehicle body, a multi-line laser radar, a controller and a PID regulator;

[0006] GNSS antenna, used to obtain the position data of the milling section and send the position data to the controller,

[0007] A multi-line laser radar is used to scan the edge of the milling section, obtain the distance data between the road surface on both sides of the edge of the milling section and the multi-line laser radar, and upload the distance data to the controller;

[0008] A controller, used for receiving position data of a GNSS antenna, obtaining a preset milling depth of a milling section from a database according to the position data, and transmitting the obtained data to a PID regulator;

[0009] The controller is also used to receive the distance data scanned by the multi-line laser radar, calculate the actual milling depth of the milling section, and transmit it to the PID regulator;

[0010] Database: used to store the milling section location data and the corresponding preset milling depth. The database is connected to the controller via CAN network communication;

[0011] A PID regulator is used for calibrating the height of the milling drum of the milling machine according to the error value between the received preset milling depth and the actual milling depth of the milling section.

[0012] Furthermore, the laser radar is installed perpendicular to the ground, with the installation axis located directly behind the edges of both ends of the milling drum of the milling machine, and the GNSS antenna is installed directly above the milling drum.

[0013] Furthermore, it also includes a blower, which is installed at both ends of the rear edge of the milling drum of the milling machine and is used to blow away asphalt particles on the edge of the milling section.

[0014] In a first aspect, the present invention provides a method for automatically calibrating a leveling zero position of a milling machine, comprising the following steps:

[0015] Pre-milling of several meters.

[0016] During the milling process, the position data of the milling section is obtained through the GNSS antenna and sent to the controller;

[0017] Scan the edge of the corresponding position of the milling section by laser radar, obtain the distance data between the road surface on both sides of the edge of the milling section at the corresponding position and the multi-line laser radar, and upload the distance data of the corresponding position to the controller;

[0018] The controller obtains a preset milling depth of the milling section from a database according to the received position data, calculates an actual milling depth of the milling section according to the received scanning data, and transmits the preset milling depth and the actual milling depth to the PID regulator;

[0019] The PID regulator calibrates the height of the milling drum of the milling machine according to the error value between the received preset milling depth and the actual milling depth of the milling section.

[0020] Furthermore, before the laser radar scanning, the asphalt particles scattered from the milled road surface are blown away by a blower.

[0021] Furthermore, the specific method for obtaining the distance data between the road surface on both sides of the edge of the milling section at the corresponding position and the multi-line laser radar includes:

[0022] The road surface sampling points on the left and right sides of the edge of the laser radar scanning milling section with an angle of θ to the laser radar axis are taken as the starting sampling points, and the sampling points on the left and right sides of the edge of the laser radar scanning milling section with an angle of φ to the laser radar axis are taken as the final sampling points. A total of m sampling points are taken on both sides, and φ is greater than θ; the starting sampling point is 2~4cm away from the edge of the milling road surface, and the final sampling point is 14~16cm away from the edge of the milling road surface.

[0023] Furthermore, the specific calculation method for calculating the actual milling depth of the milling section is:

[0024] Sort the distances of the m sampling points from small to large to get the array M , find a continuous subarray N of length n in array M, so that the variance of subarray N is the smallest among all continuous subarrays of length n in M, n≤m-3;

[0025] Among them: The variance calculation formula of subarray N is:

[0026] ,

[0027] where i is the starting index of the subarray (from 1 to m−n+1), is the jth element of array M, is the average value of array N, which is calculated as:

[0028] ,

[0029] After simplifying, we get:

[0030] ,

[0031] After that, we traverse all possible starting indexes i (from 1 to m−n+1) and update the minimum variance value minn:

[0032] ,

[0033] The index i corresponding to the minimum variance value minn is the initial index of the subarray N.

[0034] but The calculated distance between the laser radar at the current position and the edge of the milling section on both sides;

[0035] Calculate the distance between the laser radar at the current position and the edge of the milling section, and the milling depth H of the milling section is:

[0036] ,

[0037] Among them: H1 is the vertical distance between the laser radar and the unmilled road surface, and H2 is the vertical distance between the laser radar and the milled road surface.

[0038] Furthermore, the step of calibrating the height of the milling drum of the milling machine according to the error value between the received preset milling depth and the actual milling depth of the milling section specifically includes:

[0039] ,

[0040] Where: designH is the preset milling depth, errorH is the error value between the preset milling depth and the actual milling depth;

[0041] The milling error value errorH is input into the PID regulator, and the three parameters of the PID regulator input, namely the proportional coefficient kp, the integral coefficient ki and the differential coefficient kd, are adjusted, and the output is the lifting height of the milling drum.

[0042] Furthermore, the method of obtaining the milling section position data through the GNSS antenna is specifically as follows:

[0043] The longitude and latitude of the milling section of the milling machine and the heading information of the milling machine are obtained through the GNSS antenna, and the longitude and latitude of the current position and the heading information of the milling machine are transmitted to the controller. The controller reads the preset milling depth of the current position from the database; through the relative position of the multi-line laser radar and the GNSS antenna combined with the longitude and latitude of the current position of the milling machine and the heading information of the milling machine, the calibration of the multi-line laser radar scanning position and the current position of the milling machine is completed.

[0044] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention integrates laser radar ranging, data processing algorithm and milling control system, measures the actual milling depth value of the current position through multi-line laser radar and ensures the accuracy of measurement through multiple measurements and processing algorithms, extracts data from the database in combination with the milling control system, compares the milling depth value, transmits the error to the PID adjuster, realizes automatic elimination of the error, and realizes accurate and automatic calibration of the leveling zero position of the milling machine. The method can collect the working status of the milling machine and the road surface information in real time, calculates the leveling zero position through a high-precision calibration algorithm, and automatically controls the milling machine for calibration, thereby improving the construction quality and efficiency;

[0045] The present invention does not require construction to be suspended and workers to measure and calibrate, and the calibration has high accuracy and speed and does not affect the construction progress. For scenarios where the side plate is placed on the curb or there is a drop between the side plate and the milled road surface, dynamic and automatic calibration can be performed, which can achieve better milling flatness and shorten the construction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a structural schematic diagram of a milling machine leveling zero position automatic calibration system;

[0047] Figure 2 Schematic diagram of the sampling point range used for LiDAR to calculate milling depth. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0049] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship.

[0050] Example 1

[0051] like Figure 1 The embodiment shown, this embodiment provides a milling machine leveling zero position automatic calibration system, including: a GNSS antenna 1 mounted on a vehicle body 4, a multi-line laser radar 2, a controller, a PID regulator and a database;

[0052] GNSS antenna 1, used to obtain the position data of the milling section and send the position data to the controller,

[0053] The multi-line laser radar 2 is used to scan the edge of the milling section, obtain the distance data between the road surface on both sides of the edge of the milling section and the multi-line laser radar 2, and upload the distance data to the controller;

[0054] A controller, used for receiving the position data of the GNSS antenna 1, obtaining the preset milling depth of the milling section from the database according to the position data, and transmitting the obtained data to the PID regulator;

[0055] It is also used to receive the distance data scanned by the multi-line laser radar 2, calculate the actual milling depth of the milling section, and transmit it to the PID regulator;

[0056] Database: used to store the location data of the milling section and the corresponding preset milling depth. The database is established in advance. Before the construction starts, the construction design unit first uses the LiDAR 2 scanning vehicle to perform three-dimensional modeling on the milling road surface to be tested as the actual road surface. Then, a designed road surface is constructed based on the three-dimensional modeling. The elevation difference between the actual road surface and the designed road surface at each position is set, which is the preset milling depth for each position. Then, the longitude and latitude of the milling road surface to be tested and the corresponding preset milling depth are packaged into a construction file in a standard format and stored in the database.

[0057] A PID regulator is used for calibrating the height of the milling drum of the milling machine according to the error value between the received preset milling depth and the actual milling depth of the milling section.

[0058] The laser radar 2 is installed perpendicular to the ground, with the installation axis located just behind the edges of both ends of the milling drum of the milling machine, and the GNSS antenna 1 is installed just above the milling drum.

[0059] The machine also includes a blower 3, which is installed at both ends of the rear edge of the milling drum of the milling machine and is used to blow away asphalt particles on the edge of the milling section.

[0060] Example 2

[0061] like Figure 2 The embodiment shown in the figure provides a method for automatically calibrating the zero position of a milling machine, comprising the following steps:

[0062] Pre-milling process of 5 to 8 meters is carried out.

[0063] During the milling process, the longitude and latitude of the milling section of the milling machine and the heading information of the milling machine are obtained through the GNSS antenna, and the longitude and latitude of the current position and the heading information of the milling machine are transmitted to the controller. The controller reads the preset milling depth of the current position from the database; through the relative position of the multi-line laser radar and the GNSS antenna combined with the longitude and latitude of the current position of the milling machine and the heading information of the milling machine, the calibration of the multi-line laser radar scanning position and the current position of the milling machine is completed, and the position data is sent to the controller.

[0064] Before the LiDAR scan, the asphalt particles scattered from the milled road surface are blown away by a blower;

[0065] Scan the edge of the corresponding position of the milling section by laser radar, obtain the distance data between the road surface on both sides of the edge of the milling section at the corresponding position and the multi-line laser radar, and upload the distance data of the corresponding position to the controller;

[0066] The specific method for obtaining the distance data between the road surface on both sides of the edge of the milling section at the corresponding position and the multi-line laser radar includes:

[0067] The road surface sampling points on the left and right sides of the edge of the laser radar scanning milling section with an angle of θ with the laser radar axis are taken as the starting sampling points, and the sampling points on the left and right sides of the edge of the laser radar scanning milling section with an angle of φ with the laser radar axis are taken as the final sampling points. A total of m sampling points are taken on both sides, and φ is greater than θ; the starting sampling point is 3 cm away from the edge of the milling road surface, and the final sampling point is 15 cm away from the edge of the milling road surface.

[0068] The specific calculation method for calculating the actual milling depth of the milling section is:

[0069] Sort the distances of the m sampling points from small to large to get the array M , find a continuous subarray N of length n in array M, so that the variance of subarray N is the smallest among all continuous subarrays of length n in M:

[0070] Among them: The variance calculation formula of subarray N is:

[0071] ,

[0072] where i is the starting index of the subarray (from 1 to m−n+1), is the jth element of array M, is the average value of array N, which is calculated as:

[0073] ,

[0074] After simplifying, we get:

[0075] ,

[0076] After that, we traverse all possible starting indexes i (from 1 to m−n+1) and update the minimum variance value minn:

[0077] ,

[0078] The index i corresponding to the minimum variance value minn is the initial index of the subarray N.

[0079] but The calculated distance between the laser radar at the current position and the edge of the milling section on both sides;

[0080] The distance between the laser radar and the sampling points on both sides of the edge of the milling section = the axial longitudinal distance between the laser radar and the corresponding sampling point * cosα, α∈[θ,φ]; α selects the corresponding inclination angle;

[0081] Calculate the distance between the laser radar at the current position and the edge of the milling section, and the milling depth H of the milling section is:

[0082] ,

[0083] Among them: H1 is the vertical distance between the laser radar and the unmilled road surface, and H2 is the vertical distance between the laser radar and the milled road surface.

[0084] The controller obtains a preset milling depth of the milling section from a database according to the received position data, calculates an actual milling depth of the milling section according to the received scanning data, and transmits the preset milling depth and the actual milling depth to the PID regulator;

[0085] The PID regulator calibrates the height of the milling drum of the milling machine according to the error value between the received preset milling depth and the actual milling depth of the milling section.

[0086] The step of calibrating the height of the milling drum of the milling machine according to the error value between the received preset milling depth and the actual milling depth of the milling section specifically includes:

[0087] ,

[0088] Where: designH is the preset milling depth, errorH is the error value between the preset milling depth and the actual milling depth;

[0089] The milling error value errorH is input into the PID regulator, and the three parameters of the PID regulator input, namely the proportional coefficient kp, the integral coefficient ki and the differential coefficient kd, are adjusted. The output is the lifting height of the milling drum; the unmilled road surface is continued to be milled according to the calibrated milling drum.

[0090] The present invention realizes accurate and automatic calibration of the leveling zero position of the milling machine by integrating laser radar ranging, data processing algorithm and 3D milling control system. The method and system can collect the working status of the milling machine and road surface information in real time, calculate the leveling zero position through a high-precision calibration algorithm, and automatically control the milling machine for calibration, thereby improving construction quality and efficiency.

[0091] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A milling machine leveling zero position automatic calibration system, characterized in that: include: Database, GNSS antenna installed on the vehicle body, multi-line laser radar, controller and PID regulator; GNSS antenna, used to obtain the position data of the milling section and send the position data to the controller, A multi-line laser radar is used to scan the edge of the milling section, obtain the distance data between the road surface on both sides of the edge of the milling section and the multi-line laser radar, and upload the distance data to the controller; A controller, used for receiving position data of a GNSS antenna, obtaining a preset milling depth of a milling section from a database according to the position data, and transmitting the obtained data to a PID regulator; The controller is also used to receive the distance data scanned by the multi-line laser radar, calculate the actual milling depth of the milling section, and transmit it to the PID regulator; Database: used to store the milling section location data and the corresponding preset milling depth. The database is connected to the controller via CAN network communication; A PID regulator is used for calibrating the height of the milling drum of the milling machine according to the error value between the received preset milling depth and the actual milling depth of the milling section.

2. The automatic zero-position calibration system for a milling machine according to claim 1, characterized in that: The laser radar is installed perpendicular to the ground, with the installation axis located just behind the edges of both ends of the milling drum of the milling machine, and the GNSS antenna is installed just above the milling drum.

3. The automatic zero-position calibration system for a milling machine according to claim 1, characterized in that: It also includes a blower, which is installed at both ends of the rear edge of the milling drum of the milling machine and is used for blowing away asphalt particles on the edge of the milling section.

4. A method for automatically calibrating the zero position of a milling machine based on the automatic calibration system for the zero position of a milling machine according to any one of claims 1 to 3, characterized in that: include: Milling of several meters of road section is carried out in advance. During the milling process, the position data of the milling section is obtained through the GNSS antenna and sent to the controller; Scan the edge of the corresponding position of the milling section by laser radar, obtain the distance data between the road surface on both sides of the edge of the milling section at the corresponding position and the multi-line laser radar, and upload the distance data of the corresponding position to the controller; The controller obtains a preset milling depth of the milling section from a database according to the received position data, calculates an actual milling depth of the milling section according to the received scanning data, and transmits the preset milling depth and the actual milling depth to the PID regulator; The PID regulator calibrates the height of the milling drum of the milling machine according to the error value between the received preset milling depth and the actual milling depth of the milling section.

5. The method for automatically calibrating the zero position of a milling machine according to claim 4, characterized in that: Before the laser radar scanning, the asphalt particles scattered from the milled road surface are blown away by a blower.

6. The method for automatic zero-position calibration of a milling machine according to claim 4, characterized in that: The obtaining of distance data between the road surface on both sides of the edge of the milling section at the corresponding position and the multi-line laser radar comprises: The road surface sampling points on the left and right sides of the edge of the laser radar scanning milling section with an angle of θ to the laser radar axis are taken as the starting sampling points, and the sampling points on the left and right sides of the edge of the laser radar scanning milling section with an angle of φ to the laser radar axis are taken as the final sampling points. A total of m sampling points are taken on both sides, and φ is greater than θ; the starting sampling point is 2~4cm away from the edge of the milling road surface, and the final sampling point is 14~16cm away from the edge of the milling road surface.

7. The method for automatically calibrating the zero position of a milling machine according to claim 6, characterized in that: The actual milling depth of the milling section is calculated as follows: Sort the distances from the m sampling points to the laser radar from small to large to get the array M , find a continuous subarray N of length n in array M, so that the variance of subarray N is the smallest among all continuous subarrays of length n in M, n≤m-3: Among them: The variance calculation formula of subarray N is: ， Where i is the starting index of the subarray, is the jth element of array M, is the average value of array N, which is calculated as: ， Will Substitute the variance calculation formula of subarray N into it and simplify it to: ， Traverse all possible starting indexes i and update the minimum variance value minn: ， The index i corresponding to the minimum variance value minn is the initial index of the subarray N, then The calculated distance between the laser radar at the current position and the edge of the milling section on both sides; Calculate the distance between the laser radar at the current position and the edge of the milling section, and the milling depth H of the milling section is: ， Among them: H1 is the vertical distance between the laser radar and the unmilled road surface, and H2 is the vertical distance between the laser radar and the milled road surface.

8. The method for automatic zero-position calibration of a milling machine according to claim 7, characterized in that: The step of calibrating the milling drum of the milling machine according to the received error value between the preset milling depth and the actual milling depth of the milling section comprises: ， Where: designH is the preset milling depth, errorH is the error value between the preset milling depth and the actual milling depth; The milling error value errorH is input into the PID regulator, and the three parameters of the PID regulator input, namely the proportional coefficient kp, the integral coefficient ki and the differential coefficient kd, are adjusted, and the output is the lifting height of the milling drum.

9. The method for automatic zero-position calibration of a milling machine according to claim 4, characterized in that: The method of obtaining the milling section position data by using the GNSS antenna includes: The longitude and latitude of the milling section and the heading information of the milling machine are obtained through the GNSS antenna, and the longitude and latitude of the current position and the heading information of the milling machine are transmitted to the controller. The controller reads the preset milling depth of the current position from the database.

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