CN102881219B - Fruit-tree positioning map constructing device and method - Google Patents

Abstract

The invention belongs to the technical field of automatic measurement and control of agricultural machinery and equipment, and relates to a mobile vehicle-mounted device for precise positioning of fruit trees used in orchards, and in particular to a method for constructing a fruit tree positioning map, including a mobile platform, a GPS positioning module, a laser detection module, and a vulgar cruise control system. module. According to the distribution characteristics of fruit trees in the orchard, a wheeled mobile platform that can walk between the rows of fruit trees is adopted, and a laser rangefinder, an inertial measurement device, a GPS positioning module, a radar speedometer and a measurement and control board are combined to realize low-speed cruising. Under the fast and effective positioning and identification of fruit trees, to obtain the distribution information of fruit trees, create a fruit tree location map in real time, accurately obtain the growth and distribution information of fruit trees, and provide a solution for precise pesticide application of fruit trees, large-scale operation of orchards, and digital management of precision agriculture. scientific and technological means.

Description

Fruit tree positioning map construction device and method

technical field

The invention belongs to the technical field of automatic measurement and control of agricultural machinery and equipment, and relates to a mobile vehicle-mounted device for precise positioning of fruit trees in an orchard, and in particular to a method for constructing a fruit tree positioning map.

Background technique

In order to improve market competitiveness, the business model of my country's economic forest is developing in the direction of scale, systematization and digitization. Under this business model, fruit growers need to obtain accurate growth information of diverse fruit trees, such as actual growth location, trunk size, etc., based on which they can obtain the distribution of fruit trees and formulate reasonable orchard operation plans, such as tree-to-target application of pesticides, etc. In the past, fruit farmers used manual methods to obtain such information. This method was labor-intensive, extremely inefficient, and the accuracy of the information was not high. Some fruit farmers even gave up obtaining this information because of this, which led to the slow development of large-scale economic forests in my country. At present, many scholars and researchers at home and abroad use airborne surveying and mapping systems to draw agricultural and forestry information maps. This method is efficient and can obtain the distribution information of fruit tree crowns from the perspective of overlooking. It is suitable for large-scale forest areas and farmland, but the measurement accuracy is not good. High, and it is impossible to get more detailed information under the canopy (if the size and position of the tree trunk, etc.). Therefore, the development of ground-mounted vehicle-mounted surveying and mapping systems suitable for economic forest operations can effectively and accurately obtain the diverse growth information of the above-mentioned fruit trees, help fruit farmers arrange reasonable and scientific orchard operations, and provide scientific and technological means for future digital management of orchards.

Contents of the invention

The purpose of the present invention is to provide a device for constructing fruit tree positioning maps with a high level of automation, especially for real-time acquisition of fruit tree size and location information, and creating corresponding distribution maps to provide technical means for future digital management of orchards.

A kind of fruit tree positioning map construction device provided by the present invention is characterized in that: comprising:

Mobile platform: adopt a mobile platform that can walk between rows of fruit tree crops;

GPS positioning module: a component that can obtain global positioning information, installed on the top of the mobile platform;

Laser detection module: including a laser rangefinder and an inertial measurement device, in which the laser rangefinder is used to obtain the two-dimensional scanning contour data of surrounding objects, and to locate and identify the trunk of the fruit tree, and the laser rangefinder faces the fruit tree crop OK, with the laser emission center of the laser rangefinder as the origin, the relative coordinate system of the laser rangefinder is established, the x-axis is the median line of the laser rangefinder, and the y-axis is the forward direction of the mobile platform; the inertial measurement device is tightly fixed On the top of the laser range finder, it is used to measure the pitch angle, roll angle and heading angle of the laser range finder during the mobile operation in real time;

Cruise control module: mainly to control the traveling speed of the mobile platform at a speed of ≤10km/h to keep it stable, so as to avoid the increase of the measurement error of each sensor component caused by the fluctuation of traveling speed;

Main control unit: It is a military notebook computer suitable for use in harsh environments, responsible for collecting and processing data from the GPS positioning module, laser detection module and cruise control module, and obtaining fruit tree trunk positioning information and cruise control information, etc.;

In addition, the present invention also provides a method for constructing a fruit tree trunk location map by using the above fruit tree location map construction device.

Advantages of the present invention: the present invention proposes a new idea of obtaining fruit tree trunk growth and positioning information during the moving process, and is specially aimed at the distribution characteristics and growth characteristics of fruit trees in orchards, and adopts a wheeled mobile platform that can walk between rows of fruit tree crops, Combining laser rangefinder, inertial measurement device, GPS positioning module, radar speedometer and measurement and control board to realize fast and effective positioning and identification of fruit trees in low-speed cruising state, and obtain the distribution information of fruit trees synchronously to create real-time The fruit tree positioning map can accurately obtain the growth and distribution information of fruit trees, and provides scientific and technological means for precise pesticide application of fruit trees, large-scale operation of orchards, and digital management of precision agriculture.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail:

Fig. 1 is the overall layout plan view of fruit tree positioning map component device of the present invention;

Fig. 2 is the installation schematic diagram of radar speed gauge of the present invention;

Fig. 3 is the control schematic diagram of the cruise control module of the present invention;

Fig. 4 is a flow chart of the method for constructing a fruit tree location map of the present invention.

Reference signs:

1-mobile platform; 2-GPS positioning module; 3-laser range finder; 4-bracket; 5-inertial measurement device; 6-scanning area; 7-measurement and control box; Electronic accelerator; 11-motor driver; 12-control mode switching button; 13-motor; 14-accelerator pedal; 15-fruit tree; 16-RS232 to USB interface; 17-USB interface; 18-RS422 to USB interface; 19-positive Center line; 20-main control unit; 21-measurement and control board; 22-installation surface; 23-radar wave receiving and receiving surface; 24-height from the ground; 25-angle with the ground; 26-manual mode; 27-automatic mode.

Detailed ways

The construction device of fruit tree location map of the present invention, its preferred embodiment is as shown in Figure 1 to Figure 4:

As shown in FIG. 1 , the components of the device for constructing a fruit tree location map of the present invention include: a mobile platform, a GPS positioning module, a laser detection module, a cruise control module, and a main control unit.

In the present invention, the mobile platform 1 is a wheeled electric agricultural vehicle or a small tractor that can walk between rows of fruit trees. The mobile platform 1 of this embodiment selects a wheeled electric agricultural vehicle, and all components in the present invention are installed on the mobile platform 1. The mobile platform 1 has a maximum load capacity of 450kg, a maximum speed of 25km/h when fully loaded, a maximum gradeability of ≤25%, a rated power of 4.5kw, and four 12V on-board batteries to provide power for the entire fruit tree positioning map construction device.

In the present invention, the GPS (Global Positioning System) positioning module 2 is installed in the middle position of the ceiling of the mobile platform 1, and is a Trimble SPS461 positioning beacon receiver, the positioning accuracy reaches centimeter level, waterproof and dustproof, and the data output update rate is 5Hz, which is transferred by RS232 The USB interface 16 communicates data with the main control unit 20 .

In the present invention, the laser detection module includes a laser rangefinder 3 and an inertial measurement device 5, and the laser rangefinder 3 is installed on the left side of the mobile platform 1 at a distance of 60 cm from the ground on the left side of the mobile platform 1 through a bracket 4, facing fruit trees 15 crop rows , horizontal two-dimensional scanning of the trunk of the fruit tree 15, the scanning angle resolution is 0.25°, the scanning area 6 is set to 100°, the maximum measurement distance is 8m, data communication is carried out with the main control unit 20 through the USB interface 17, and the data output update frequency is 18.7Hz; as shown in Figure 1, with the laser emission center of laser rangefinder 3 as the origin, the relative coordinate system of laser rangefinder 3 is established, the x-axis is the median line 19 of laser rangefinder 3, and the y-axis is the forward direction of the mobile platform 1; the inertial measurement device 5 is tightly fixed on the top of the laser range finder 3, and is used for real-time measurement of the pitch angle, roll angle and heading angle of the laser range finder 3 during the mobile operation, and the main control unit 20. Data communication is performed through the RS422 to USB interface 18, and the data output update frequency is 100Hz.

In the present invention, the construction device of the fruit tree positioning map usually operates at a relatively low speed (≤10km/h), and the cruise control module mainly controls the traveling speed of the mobile platform 1 at such a relatively low speed to keep it stable. Thereby avoiding the measurement error increase of each sensor part caused by the fluctuation of traveling speed; the cruise control module consists of a measurement and control box 7, a radar speedometer 8, a steering wheel 9, an electronic throttle 10, a motor driver 11, and a control mode switch button 12, a motor 13, and an accelerator pedal 14; wherein the steering wheel 9, the electronic accelerator 10, the motor driver 11, the motor 13 and the accelerator pedal 14 are all original accessories of the mobile platform 1, and the electronic accelerator 10 is an inductive electronic accelerator. The model is ipPDMG-B-5.0, and the motor 13 is a brushed separately excited DC motor ZT3-48 with a rated power of 3kW and a rated speed of 2800r/min.

Radar speedometer 8 is used to detect the actual speed of travel of mobile platform 1, as shown in Figure 2, the mounting surface 22 of radar speedometer 8 is fixed on the tail middle position (as shown in Figure 1) of mobile platform 1 by special support, radar The distance between the center of the wave receiving surface 23 and the height 24 of the ground is 70cm, and the included angle 25 between the normal direction of the radar wave receiving surface 23 and the ground is 35°; the radar wave frequency is 24.125GHz±50MHz, and the measurement range of the radar speedometer 8 is 0.53～107.8 km/h, the output frequency is 27.45Hz/km/h.

As shown in Figure 3, the cruise control module is divided into a manual mode 26 and an automatic mode 27: in the manual mode, the driver steps on the accelerator pedal 14, and the accelerator pedal 14 controls the electronic accelerator 10 to send a voltage of 0 to 5V to the motor driver 11 for control. signal, and then the motor driver 11 drives the motor 13 to adjust the speed of the motor 13, thereby keeping the moving speed of the mobile platform 1 stable; One counter channel is collected and transmitted to the main control unit 20. The main control unit 20 converts the frequency signal of the radar speedometer 8 into the actual travel speed, and then according to the difference between the actual travel speed and the expected travel speed, through the measurement and control board 21 One analog output channel sends a voltage control signal of 0 to 5V to the motor driver 11 to adjust the speed of the motor 13, so that the mobile platform 1 maintains the expected travel speed; the measurement and control board 21 is a ZTUSB-7660DN data acquisition card with 48 There are single-ended/24 differential analog input channels, 4 analog output channels, 3 counter channels, 16 digital input channels and 16 digital output channels, and communicate with the main control unit 20 through the USB interface 17 . The manual mode and the automatic mode of the cruise control module are switched by the control mode switching button 12, and Fig. 3 shows that the normally closed state of the control mode switching button 12 is the manual mode, and the normally open state is the automatic mode, and the driver presses the control mode switching button After 12, the button glows red, and the cruise control module switches to the automatic mode. When the button is popped up, the button does not emit light, and it switches to the manual mode at the same time; the control mode switching button 12 is installed on the top cover of the measurement and control box 7, and the measurement and control box 7 is placed The position on the right side of the driver can be easily touched (Figure 1), which is convenient for the driver to operate; whether the cruise control module is in the manual mode or the automatic mode, the driver needs to control the direction of travel of the mobile platform 1 through the steering wheel 9. Try to ensure that the mobile platform 1 walks along a straight line, and keep the distance between the laser rangefinder 3 and the crop rows of the fruit trees 15 within the range of 70-100 cm.

In the present invention, the main control unit 20 is a military notebook computer suitable for use in harsh environments. The main frequency of the CPU is a 2.4GHz dual-core processor, the memory is 3GB, and the hard disk is 250GB. It can be used in harsh environments such as humidity, dust, pollution, and vibration , meet the job requirements. The main control unit 20 is installed on the right side of the steering wheel 9 by the vehicle-mounted bracket, and the positions of the vehicle-mounted bracket and the main control unit 20 can be adjusted according to the driver's habits, so that the driver monitors the content displayed by the main control unit 20 in real time;

In the present invention, in order to avoid being affected by humidity and dust in the working environment, the measurement and control board 21 is placed in a waterproof and dustproof measurement and control box 7; the main control unit 20 is also specially equipped with a 12V DC to 220V AC vehicle-mounted inverter. The 12V vehicle-mounted storage battery on the mobile platform 1 provides power supply, and the vehicle-mounted inverter is also placed in the measurement and control box 7; The tachymeter 3 and the inertial measurement unit 5 provide a 12V DC power supply.

The construction of the fruit tree location map and the cruise control of the mobile platform 1 in the automatic mode are carried out in independent threads respectively. The method for constructing the fruit tree location map is described in detail below in conjunction with FIG. 4 :

(1) The data acquisition of the laser range finder 3, the trunk location recognition and the location map generation are completed in the main thread. In Fig. 1, the laser rangefinder 3 emits and receives the scanning laser beam counterclockwise relative to the laser emission center. After completing one scan, a set of two-dimensional scanning point cloud data of surrounding objects is obtained, including the scanning angle and the distance between the object and the laser beam at this angle. The straight-line distance of the laser emission center of the rangefinder 3 (that is, the measurement distance); firstly, filter according to the measurement distance, and remove the point cloud data points whose measurement distance exceeds the range A, to avoid the interference of background noise, and the range A is set to fruit trees 15 crops 1.5 times the vertical distance to the laser rangefinder 3; then calculate the jump distance between the point cloud data points, use the threshold B to cluster the point cloud data, and the data points whose jump distance does not exceed the threshold B are considered Contour points on the trunk of the same fruit tree 15 are divided into the same cluster and labeled; otherwise, contour points on different trunks are divided into different clusters; speed determination;

(2) Assuming that the cross section of the trunk of the fruit tree 15 is a standard circle, the diameter of the standard circle is the size of the trunk of the fruit tree 15, and the center position of the standard circle is the position of the trunk of the fruit tree 15, and the point cloud data after clustering is only the standard of the cross section of the trunk of the fruit tree 15 For a section of the arc of a circle, use the least square method to carry out standard circle fitting on the point cloud data points of the same cluster to obtain the diameter and center of the standard circle, which are the size and position of the trunk cross section of the fruit tree 15, and record the main control unit at the same time The system time of 20 is called the laser acquisition time;

(3) The collection of GPS positioning data is carried out in another independent thread, and GPS positioning data comprises the system time (being called GPS collection moment) of main control unit 20, longitude and latitude information, speed of travel and course angle; In another independent thread , the active unit 20 monitors the opening and closing state of the control mode switching button 12 in real time through a digital input channel of the measurement and control board 21, and when it is detected that the control mode switching button 12 is pressed, the program enters the cruise control of the mobile platform 1 in the automatic mode , travel at a constant speed at the set expected travel speed; when it is detected that the control mode switching button 12 pops up, switch to the manual mode and prompt the driver to control the travel speed of the mobile platform 1; the travel speed and heading angle in the GPS positioning data And the actual speed of travel detected by the radar speedometer 8 is transmitted to the main thread from respective threads by thread queues respectively; Fusion to finally determine the travel speed and heading angle of the mobile platform 1;

(4) The fruit tree 15 trunk size and the position data update frequency provided by the laser range finder 3 are 18.7Hz, and the GPS data update frequency is 5Hz. In order to further improve the positioning accuracy, before the above data is updated next time, according to the laser range finder 3 The current obtained fruit tree 15 trunk position, the speed of travel and the heading angle of the mobile platform 1 obtained after data fusion, predict the movement trend of the fruit tree 15 trunk by reverse interpolation at an interval of 10ms, and obtain the predicted positions of several fruit tree 15 trunks relative to the mobile platform, The laser acquisition time is increased by 10ms for each interpolation;

(5) calculate the vertical distance of some fruit trees 15 trunk predicted positions obtained by step (4) to the median line 19 of the laser range finder 3, because the trunk predicted position is just in time on this center line 19 of the laser range finder 3 Time is difficult to capture, so the predicted position of the trunk with the shortest distance is taken as the position facing the laser range finder 3, and according to the laser collection time and GPS collection time at this time, the latitude and longitude in the GPS positioning data at the laser collection time are interpolated information, while the RS232 transfer USB interface reads the data of the inertial measurement device 5, and obtains the GPS positioning data under the laser acquisition moment, the trunk size and predicted position information of the fruit tree 15, the pitch angle, roll angle and heading angle of the laser range finder 3;

(6) the predicted position of the fruit tree 15 trunks obtained by step (5) is the position in the relative coordinate system of the laser range finder 3, and the latitude and longitude information is the position of the GPS positioning module 2 in the geodetic coordinate system in the GPS positioning data; According to the mutual positional relationship between the GPS module 2 and the laser range finder 3, the GPS positioning data under the laser system time, the trunk size and predicted position information of the fruit tree 15, the pitch angle, roll angle and heading angle of the laser range finder 3, The predicted position of the trunk of the fruit tree 15 under the relative coordinates is transformed into the earth coordinate system, thereby obtaining the actual position of the trunk of the fruit tree 15;

(7) according to the size and actual position of fruit tree 15 trunks, generate fruit tree positioning map in real time, and show on the display screen of main control unit 20, simultaneously laser system time, the GPS location data under this system time, fruit tree 15 trunk sizes and predicted position information, the pitch angle, roll angle and heading angle of the laser rangefinder 3 are stored in the database, which is convenient for operators to perform data management and map generation in the future.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or modifications within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention.

Claims (5)

1. A fruit tree positioning map construction device, characterized in that: comprising: Mobile platform: adopt a mobile platform that can walk between rows of fruit tree crops; GPS positioning module: a component that can obtain global positioning information, installed on the top of the mobile platform; Laser detection module: including a laser rangefinder and an inertial measurement device, in which the laser rangefinder is used to obtain the two-dimensional scanning contour data of surrounding objects, and to locate and identify the trunk of the fruit tree, and the laser rangefinder faces the fruit tree crop OK, with the laser emission center of the laser rangefinder as the origin, the relative coordinate system of the laser rangefinder is established, the x-axis is the median line of the laser rangefinder, and the y-axis is the forward direction of the mobile platform; the laser rangefinder is completed After one scan, a set of two-dimensional scanning point cloud data of surrounding objects is obtained, including the scanning angle and the straight-line distance from the object at this angle to the laser emission center of the laser rangefinder, that is, the measurement distance; firstly, filtering is performed according to the measurement distance, and the measured The point cloud data points whose distance exceeds the range A are eliminated; then the jump distance between the point cloud data points is calculated, and the point cloud data is clustered using the threshold B, and the data points whose jump distance does not exceed the threshold B are considered to be the same fruit tree The contour points on the trunk are divided into the same cluster and labeled; assuming that the cross-section of the fruit tree trunk is a standard circle, the diameter of the standard circle is the size of the fruit tree trunk, and the center position of the standard circle is the fruit tree trunk position. The point cloud data points are fitted with a standard circle to obtain the diameter and center of the standard circle, which is the size and position of the cross-section of the fruit tree trunk; the inertial measurement device is tightly fixed on the top of the laser rangefinder to measure the distance of the laser rangefinder in real time. Pitch angle, roll angle and heading angle during mobile operation; Cruise control module: mainly to control the traveling speed of the mobile platform at a speed of ≤10km/h to keep it stable; Main control unit: It is a military notebook computer suitable for use in harsh environments. It is responsible for collecting and processing data from the GPS positioning module, laser detection module and cruise control module, and obtaining fruit tree trunk positioning information and cruise control information. 2. according to the described fruit tree positioning map construction device of claim 1, it is characterized in that: the cruise control module includes a measurement and control box, a radar speedometer, a steering wheel, an electronic throttle, a motor driver, a control mode switching button, a motor, and an accelerator pedal; cruise control The module is divided into manual mode and automatic mode. In manual mode, the driver steps on the accelerator pedal to control the electronic accelerator to send a voltage control signal to the motor driver, and then the motor driver drives the motor to keep the speed of the mobile platform stable; in automatic mode Next, the actual travel speed of the mobile platform is detected by the radar speedometer, and transmitted to the main control unit through a measurement and control board. The main control unit sends a voltage to the motor driver through the measurement and control board according to the difference between the actual travel speed and the expected travel speed. The control signal adjusts the rotation speed of the motor so that the mobile platform can maintain the expected travel speed. the 3. The fruit tree location map construction device according to claim 2, characterized in that: the measurement and control board is placed in the measurement and control box, the main control unit is equipped with a 12V DC to 220V AC vehicle-mounted inverter, and the 12V vehicle-mounted inverter on the mobile platform The battery provides power, and the on-board inverter is also placed in the measurement and control box; in addition, the measurement and control box is also equipped with a fuse group, and the on-board battery provides 12V DC power to the GPS positioning module, laser range finder and inertial measurement device respectively through the fuse group . the 4. according to the described fruit tree positioning map construction device of claim 2, it is characterized in that: GPS positioning module carries out data communication with main control unit through RS232 transfer USB interface; Laser range finder carries out data communication with main control unit through USB interface; The inertial measurement device and the main control unit perform data communication through the RS422 to USB interface; the measurement and control board performs data communication with the main control unit through the USB interface. 5. a kind of method that the fruit tree location map construction device described in application claim 1 carries out the method for fruit tree trunk location map construction, laser range finder data collection, trunk location recognition and location map generation are completed in main thread, it is characterized in that: (1) After the laser rangefinder completes a scan, a set of two-dimensional scanning point cloud data of surrounding objects is obtained, including the scanning angle and the straight-line distance from the object at this angle to the laser emission center of the laser rangefinder, that is, the measurement distance; first Filter according to the measurement distance, and remove the point cloud data points whose measurement distance exceeds the range A; then calculate the jump distance between the point cloud data points, use the threshold B to cluster the point cloud data, and the jump distance does not exceed the threshold B The data points of are considered as contour points on the trunk of the same fruit tree, which are divided into the same cluster and labeled; (2) Assuming that the cross-section of the fruit tree trunk is a standard circle, the diameter of the standard circle is the size of the fruit tree trunk, and the center position of the standard circle is the position of the fruit tree trunk, the standard circle is simulated for the same cluster point cloud data points obtained in step (1). Combined, the diameter and center of the standard circle are obtained, which is the size and position of the cross-section of the fruit tree trunk. At the same time, the system time of the main control unit is also recorded, which is called the laser acquisition time; (3) The collection of GPS positioning data is carried out in an independent thread, and the system time of GPS positioning data including main control unit is called GPS acquisition time, longitude and latitude information, speed of travel and course angle; In another independent thread, main control unit The on-off state of the control mode switching button is monitored in real time through the measurement and control board. When the control mode switching button is detected to be pressed, the program enters the cruise control of the mobile platform in the automatic mode, and travels at a constant speed as expected; when the control mode switching is detected The button pops up and switches to manual mode, prompting the driver to control the traveling speed of the mobile platform; the main control unit performs data fusion according to the traveling speed and heading angle in the GPS positioning data and the actual traveling speed detected by the radar speedometer, and finally Determine the travel speed and heading angle of the mobile platform; (4) According to the current position of the trunk of the fruit tree obtained by the laser range finder, the speed of travel and the heading angle of the mobile platform obtained after data fusion, reverse interpolation predicts the movement trend of the trunk of the fruit tree relative to the mobile platform, and obtains the predicted positions of the trunk of several fruit trees; (5) calculate the vertical distance from some fruit tree trunk prediction positions obtained by step (4) to the median line of the laser range finder, get the shortest trunk prediction position wherein the distance is as the position facing the laser range finder, according to the current position At the time of laser collection and GPS collection, interpolation calculates the latitude and longitude information in the GPS positioning data at the time of laser collection, and at the same time reads the data of the inertial measurement device to obtain the GPS positioning data at the time of laser collection, the size of the trunk of the fruit tree and the predicted position information. Pitch angle, roll angle and heading angle of the laser rangefinder; (6) According to the positional relationship between the GPS module and the laser range finder, the GPS positioning data at the time of laser collection, the trunk size of the fruit tree and the predicted position information, the pitch angle, roll angle and heading angle of the laser range finder, will be compared to The predicted position of the trunk in the coordinates is transformed into the earth coordinate system, so as to obtain the actual position of the trunk of the fruit tree; (7) According to the size and actual position of the fruit tree trunk, a fruit tree location map is generated in real time and displayed on the display screen of the main control unit. At the same time, the laser system time, the GPS positioning data under the system time, the size of the fruit tree trunk and the predicted position Information, the pitch angle, roll angle and heading angle of the laser rangefinder are stored in the database. the