WO2021238421A1

WO2021238421A1 - Wheeled agricultural robot having self-adaptive wheel distance adjustment function, and adjustment method therefor

Info

Publication number: WO2021238421A1
Application number: PCT/CN2021/085757
Authority: WO
Inventors: 崔龙飞; 薛新宇; 乐飞翔; 孙涛; 陈晨; 张宋超; 孙竹; 徐阳; 顾伟; 丁素明; 金永奎; 张玲; 周立新
Original assignee: 农业农村部南京农业机械化研究所
Priority date: 2020-05-27
Filing date: 2021-04-07
Publication date: 2021-12-02
Also published as: AU2021203787B2; AU2021203787A1; CN111645777A; CN111645777B

Abstract

A wheeled agricultural robot having a self-adaptive wheel distance adjustment function, and an adjustment method therefor. The wheeled agricultural robot comprises a control system, a body (3) provided with four driving wheel legs, and a wheel distance adjustment actuator. By means of adjustment modes such as synchronous adjustment of the wheel distances, independent adjustment of two wheels, and independent adjustment of the four wheels, the wheel distances can be adjusted adaptively according to changes of the crop row spacing and the terrain to reduce the phenomenon of crop crushing, and ensure that the chassis can smoothly pass through complex terrains having obstacles or narrow sections, thereby improving the working efficiency and reducing the operation cost.

Description

Wheeled agricultural robot with adaptive wheel track adjustment function and adjustment method thereof

Technical field

The invention belongs to the technical field of agricultural machinery, and specifically relates to a wheeled agricultural robot with an adaptive wheel track adjustment function and an adjustment method thereof.

Background technique

With the growing population and the shortage of water and soil resources and labor in agricultural production, there is an urgent need to improve the efficiency of agricultural production. It is an inevitable trend of the development of agricultural mechanization to use agricultural robots to completely or partially replace humans to complete complex tasks efficiently, safely and reliably.

For example, the prevention and control of crop diseases, pests and weeds in my country has become the most labor-intensive, labor-intensive, and frequently-frequent operation link in the agricultural production process, and spraying pesticides, herbicides and other pesticides and liquid fertilizers not only wastes the phenomenon, but also It will seriously harm the environment, so intelligent field management robots have become a research hotspot in the industry. With the help of robots, field fine management operations such as pesticide application, fertilization, weeding, and crop information collection can be carried out. In terms of pesticide application/fertilization, the intelligent field management robot adopts the concept of precise spraying, using computer vision technology to detect weeds, and then spraying herbicides in a targeted manner, which can significantly reduce the amount of herbicides used in crop growth.

However, there are many hills and mountains in our country, and the planting of crops that are planted or transplanted by machinery will cause inconsistent planting row spacing due to the accuracy of the machinery and uneven ground. Manned boom sprayers, cultivating weeders, and conventional autonomously-driving agricultural robots will all have the phenomenon of wheel pressing, although in most cases the driver drives the working machine along the crop line, and the autonomous navigation robot is based on the crop line in real time. It adjusts the heading of the chassis, but these field management tools do not have the function of self-adjusting the wheelbase. Ground obstacles such as bumps and pits will still cause the chassis to bump or small agricultural robots cannot pass.

Summary of the invention

The technical purpose of the present invention is to provide a wheeled agricultural robot with an adaptive wheel track adjustment function and an adjustment method thereof, so that the wheel track of the robot can be adjusted adaptively with the row distance of the crop, and the phenomenon of pressing seedlings during the operation is greatly reduced. At the same time, if obstacles or narrow sections are encountered, it can also ensure that the chassis can pass smoothly.

In order to achieve the above technical objectives, the technical solutions provided by the present invention are as follows:

A wheeled agricultural robot with an adaptive wheel track adjustment function, comprising a control system and a vehicle body with four driving wheel legs, and is characterized in that it is also provided with a track adjustment actuator;

The four driving wheel legs of the car body are each connected to the chassis frame through a corresponding rocker arm. The driving wheel legs include wheels and steering devices. Each wheel is driven by an independent hub motor. The drive circuit and control of the hub motor System connection

The steering device includes a steering motor that controls the steering of the wheels and a motor mounting seat, the motor mounting seat is connected to the lower wheel through a wheel leg bracket; If the inner turning pair is connected to the chassis frame, the rocker arm can swing horizontally relative to the longitudinal axis of the vehicle body with the rocker arm pivot as the center, changing the distance from the corresponding wheel to the longitudinal axis of the vehicle body;

The wheel track adjustment actuator includes a driving device, a first electromagnetic clutch, a second electromagnetic clutch, and two front and rear linear slide devices. The two linear slide devices are laid and installed on the chassis frame along the longitudinal axis of the vehicle body. Both are driven by the driving device through the transmission mechanism. The driving device transmits power to the slider of the forward linear slide device through the first electromagnetic clutch, and transmits power to the slider of the rear linear slide device through the second electromagnetic clutch. The control signal input ends of the driving device and the two electromagnetic clutches are respectively connected to the control system, and the control system controls the start-stop and on-off;

The left and right driving wheel legs at the front of the car body are each connected to the sliding block on the front linear slide device through a pair of linkage structure, and the left and right driving wheel legs at the rear of the car body are each connected to the rear linear slide device through a pair of linkage structure. The connecting rod structure is composed of a driving link and a rocker arm extension rod. One end of the two is connected by a rotating pair and a self-locking connector. At the same time, the other end of the rocker arm extension rod is connected to the rocker arm. The fixed connection is used to drive the rocker arm to rotate, and the other end of the driving link is hinged with the corresponding slider through a rotating pair, which converts the linear motion of the slider to drive the rocker arm extension rod to rotate with the rocker arm axis as the center Rotational movement

The self-locking connector is composed of a first connecting block, a second connecting block and a positioning pin electromagnet; one of the connecting blocks is equipped with a locking electromagnet, after the locking electromagnet is energized, the two connecting blocks are fastened by magnetic attraction Connected, the self-locking connector is in the combined state; the first connecting block is fixedly installed at the end of the rocker arm extension rod, the second connecting block is connected with the driving link through the rotating pair; the second connecting block is provided with a limiter Position hole, the positioning pin electromagnet is installed on the drive connecting rod; when the locking electromagnet loses power, the first and second connecting blocks lose the magnetic restraint, then the self-locking connector is disconnected, and the control system controls the positioning pin electromagnet to act at the same time , Insert its protruding pin into the limiting hole of the second connecting block to prevent the second connecting block from rotating freely;

The wheeled agricultural robot includes the following four wheelbase adjustment modes:

A) Four-wheel track synchronization adjustment mode: the first and second electromagnetic clutches and their respective locking connectors are in a combined state, and the driving device adjusts the track of the front and rear wheels synchronously through two linear slide devices;

B) Front wheel track independent adjustment mode: the first electromagnetic clutch and the respective locking connectors are in the combined state, the second electromagnetic clutch is disconnected, and the driving device adjusts the track of the front wheels through the front linear slide device;

C) Rear wheel track independent adjustment mode: the second electromagnetic clutch and the respective locking connectors are in the combined state, the first electromagnetic clutch is disconnected, and the driving device adjusts the track of the rear wheels through the rear linear slide device;

D) Four-wheel position independent adjustment mode: the first and second electromagnetic clutches and their respective locking connectors are disconnected, and the distance between the four wheels and the longitudinal axis of the car body can be adjusted independently without interference;

Among them, A), B), C) are active adjustment modes, which drive the rocker arm to swing laterally by controlling the drive device; D) is a passive adjustment mode, which drives the corresponding wheels forward or backward by individually controlling the rotation of the hub motor, thus driving the corresponding wheels forward or backward. The swing arm swings laterally, changing the distance from the wheel to the longitudinal axis of the vehicle body.

On the basis of the above scheme, further improved or preferred schemes also include:

Further, the second connecting block is a convex block, and the butting surface with the first connecting block is provided with a convex structure, the first connecting block is a concave block, and the butting surface is provided with a shape suitable for the convex structure. The groove structure is equipped with a pressure sensor and a travel switch. The signal output terminals of the pressure sensor and the travel switch are connected to the control system. When the first and second connecting blocks are adsorbed, the convex structure is embedded In the groove structure, the pressure sensor and the travel switch can be touched. If the signal fed back by the pressure sensor is not less than the preset threshold, the control system considers the connecting rod structure to be firmly fixed, from mode A)-C) Select the appropriate active adjustment mode to activate the corresponding slider.

Further, the first connection block is provided with two plug-in boards, the two plug-in boards are located on the left and right sides of the groove structure, protruding from the mating surface of the first connection block, and the second connection block is in a corresponding position It is provided with an adapted slot; when the first connection block and the second connection block are attracted by magnetic force, the plug-in board of the first connection block is stuck in the slot of the second connection block, and the inner side of the two plug-in boards is provided with facing The chamfered bevel of the convex structure.

Preferably, the driving device is set as a servo motor, the linear slide device adopts a lead screw electric slide device, and the servo motor is installed in the middle of the chassis frame and located between the two lead screw electric slide devices; two electromagnetic clutches They are respectively installed at the power input end of the two-screw electric slide rail device close to the center of the chassis. The output shaft of the servo motor is connected to the input shafts of the two electromagnetic clutches through the transmission mechanism. Screw electric slide rail device.

Further, a grating ruler is provided on the side of the linear slide rail device for measuring the stroke of the slider on the track, and is connected with a control system, which realizes precise control of the wheel base by controlling the stroke of the slider.

Further, the wheeled agricultural robot is provided with a navigation system, and the control system controls the action of the wheel base adjustment actuator according to the signal fed back by the navigation system;

The navigation system includes a terrain detection sensor, a satellite positioning receiver and an inertial sensor. The control system analyzes the terrain information detected by the terrain detection sensor, the position information of the vehicle body received by the satellite positioning receiver, and the vehicle body attitude information fed back by the inertial sensor. The position and row spacing of the crop row in front of the vehicle body, and calculate the adjusting amount of the wheel track adapted to it, so as to output the corresponding control signal to the wheel track adjustment actuator.

A manual wheel track adjustment method based on the wheeled agricultural robot, applied to passive adjustment mode D), performed in a non-driving state of the vehicle body, characterized in that it includes the following steps:

1) The operator plans in advance the track adjustment amount of each driving wheel leg wheel according to the terrain in front of the vehicle body or the crop row spacing, and based on the track adjustment amount, sends an adjustment instruction to the robot control system through the remote control terminal;

2) After receiving the adjustment command, the control system first controls to disconnect from each locking connector; then, the driving device that controls the wheel track adjustment actuator is started, pushing the slider on the linear slide device back to the initial position; secondly, the control The first and second electromagnetic clutches are disconnected at the same time; finally, the corresponding control commands are output to the hub motor and the steering motor to drive the wheels to move forward or backward around the rocker arm shaft to change the vertical distance between the wheels and the longitudinal axis of the vehicle body , When the wheel is adjusted in place, the hub motor is controlled to stop, and the electric brake at the rocker shaft is controlled to act immediately to fix the track.

An automatic wheel track adjustment method based on the wheeled agricultural robot, applied to the active adjustment mode A), B) or C), characterized in that it comprises the following steps:

1) Install the 3D lidar as a terrain detection sensor on the front of the car body. During the driving of the agricultural robot, the 3D lidar is used to scan the ground and crops in front, and the geographical position data and inertia of the car body sent by the satellite positioning system The chassis frame attitude data fed back by the sensor establishes a field scene three-dimensional point cloud image based on the vehicle body, and converts the field scene three-dimensional point cloud image into a point cloud image based on the geodetic coordinate system OXYZ, where the vertical Z coordinate represents the three-dimensional point Ground clearance, the X direction represents the longitudinal direction of the horizontal plane, that is, the direction in which the robot is traveling, and the Y direction represents the horizontal direction perpendicular to the X direction on the horizontal plane;

2) According to the type of crop and its growth stage, set an appropriate crop height threshold, and determine that the point in the field scene 3D point cloud map with the height coordinate greater than the height threshold is the point of the crop row cluster, so that the crop row cluster points The cloud is separated from the three-dimensional point cloud diagram, and then the midpoint of each crop row cluster is calculated, and the longitudinal line of the midpoint is the centerline of the crop row;

3) After obtaining the center line of each crop row, according to the current position of the robot body, the row spacing of the crop in front of the car body is calculated in real time, combined with the position between the rows of the left and right wheels of the car body or the number of rows crossed, calculate the front and rear two The theoretical width of the set of wheels, that is, the target width of the track adjustment;

4) Obtain the actual width of the wheelbase, calculate the difference between the actual width of the wheelbase and the target width of the wheelbase adjustment. Based on the control strategy of the wheelbase following the change of the crop line, the control system outputs the corresponding control instructions to the linear slide device, and through sliding The movement of the block drives the rocker arm to rotate through a certain yaw angle, and adjusts the distance between the front and/or rear wheels and the longitudinal axis of the vehicle body to adapt it to the distance between the crop rows in front of the vehicle body.

Further, in step 1), on the basis of the three-dimensional point cloud image of the field scene, the RANSAC algorithm is used to fit a Hessian plane equation, and the detection ground is refined and reconstructed through least square fitting.

Beneficial effects:

The wheeled agricultural robot of the present invention can make adaptive adjustments to the wheel pitch according to the change of crop row spacing and terrain, greatly reduce the occurrence of seedling pressing, broaden the applicable terrain range for agricultural robots to perform operations, and improve work efficiency. Reduce operating costs, and the present invention has multiple adjustment modes such as synchronous adjustment of wheel track, two-wheel independent adjustment and four-wheel independent adjustment. If obstacles, narrow sections and other complex terrain are encountered, it can also ensure that the chassis can pass smoothly. , Reasonable structural planning, easy to operate and maintain, suitable for popularization and use.

Description of the drawings

FIG. 1 is a schematic diagram of the overall structure of a specific embodiment of the agricultural robot of the present invention;

Fig. 2 is a schematic diagram of the structure of the driving wheel leg of the agricultural robot in Fig. 1;

Figure 3 is a schematic diagram of a crop row;

Figure 4 is a schematic diagram of the structure of the wheel track adjustment actuator;

FIG. 5 is a topological structure diagram of the agricultural robot in the embodiment of FIG. 1 that realizes automatic adjustment of the wheelbase;

Fig. 6 is a control principle diagram of adaptive adjustment of wheel base;

Figure 7 is a schematic diagram of the connecting rod structure;

Figure 8 is a structural schematic diagram 1 of the self-locking connector;

Figure 9 is a second structural diagram of the self-locking connector;

Figure 10 is a schematic diagram of the structure of the bump;

Figure 11 is a schematic diagram of the structure of the concave block;

Figure 12 is a schematic diagram of the installation of the pressure sensor and the travel switch;

Figure 13 is five views of the bump;

Figure 14 is a structural schematic diagram 1 of the wheel track adjustment actuator and the driving wheel leg;

Figure 15 is the second structural diagram of the wheel track adjustment actuator and the driving wheel leg;

Figure 16 is a partial structural diagram of the wheel track adjustment actuator and the driving wheel leg;

Figure 17 is a schematic diagram of the structure of the wheel base adjustment actuator, the chassis frame and the driving wheel legs;

Figure 18 is a schematic diagram of the chassis track control.

Detailed ways

In order to describe the technical solutions of the present invention in detail, the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, a wheeled agricultural robot with adaptive wheelbase adjustment function includes a vehicle body 3, a control system, a navigation system, a wheelbase adjustment actuator and a pesticide application system. The vehicle body 3 is provided with four driving wheel legs, front, rear, left, and right. The wheels 10 of each driving wheel leg are driven by an independent hub motor 14, which can realize four-wheel differential speed, and each wheel 10 has an independent steering device. 8. The navigation system, the track adjustment actuator, the drug application system, the wheel hub motor 10 and the steering device 8 are respectively connected to the control system, and the control system controls the start and stop.

The medicine application system includes a medicine box 4, a spray bar 1 and an infusion pipeline. The medicine box 4 is installed on the vehicle body 3, and the spray bar 1 is hung on the rear of the vehicle body 3 through a self-balancing spray bar suspension 2.

The navigation system includes components such as a terrain detection sensor 6, a satellite positioning receiver 4, an inertial sensor, and a wheel odometer. The terrain detection sensor 6 is installed on the front of the vehicle body to detect terrain information including the ground and crops, preferably a three-dimensional lidar (three-dimensional scanning laser sensor); the satellite positioning receiver 4 is connected to a satellite positioning system , Used to provide real-time driving position information of the car body 3; inertial sensors are installed on the car body to detect the attitude of the car body or the chassis frame of the car body, including data such as pitch angle and roll angle; wheel odometer also It can be a rotary encoder, used to measure the rotation angle and speed of the wheels, and can further calculate the distance traveled by each wheel. The robot needs to perceive the farmland scene when driving in the field, generate a heading reference trajectory, and then calculate the four from the heading reference trajectory For the target speed of each wheel hub motor, the control system controls the speed of the four hub motors in real time to track the target speed. The wheel odometer measures the wheel speed as the feedback input of the control system for real-time closed-loop control.

The control system analyzes the position and row spacing of the crop row in front of the vehicle body 3 according to the data fed back by the navigation system, calculates the adaptive wheel base adjustment amount, and outputs the corresponding control signal to the wheel base adjustment actuator.

The four driving wheel legs of the vehicle body 3 are each connected to the chassis frame through a rocker arm 7. Each driving wheel leg includes a wheel 10 and a steering device 8 that individually controls the wheel 10. The steering device 8 is composed of a steering motor and a motor mounting seat. The motor mounting seat is arranged above the wheel leg bracket 9, and the upper part of the wheel leg bracket 9 is connected to the motor mounting seat through a vertical bracket shaft, and the steering motor is activated to drive the wheel leg bracket 9 and the wheel 10 to turn. The outer end of the rocker arm 7 is fixedly connected to the motor mounting base, and the inner end is connected to the chassis frame through the first rotating pair. The rotating shaft of the first rotating pair is the rocker arm rotating shaft 12, which is vertically installed on the chassis frame and fixedly connected with the rocker arm 12. When the rocker arm 7 rotates with the rocker arm shaft 12 as the center, it can drive the driving wheel legs to swing laterally and change the distance from the wheel 10 to the longitudinal axis (longitudinal center line) of the vehicle body. At the same time, an angle sensor 11 is installed on the rocker shaft 12 or the chassis frame to detect the rotation angle of the rocker shaft 12, and the angle sensor 11 is connected to the control system for feedback of the yaw angle of the rocker arm, preferably a rotation Encoder.

The wheel track adjustment actuator includes a first electromagnetic clutch 17-1, a second electromagnetic clutch 17-2, a driving device 18, a gear reduction box and two front and rear linear slide devices.

Two sections of linear slide rail devices are laid and installed on the chassis frame along the longitudinal axis of the car body. In this embodiment, the driving device 18 adopts a servo motor, and the linear slide device adopts a lead screw electric slide rail device.

The screw electric slide rail device is composed of a screw 15-1, a guide rail 15-2 and a sliding block 15-3. The two guide rails 15-2 are respectively arranged on the left and right sides of the screw 15-1, and Parallel; the sliding block 15-3 is installed on the two guide rails 15-2 and connected with the screw nut. When the screw is driven by the servo motor, the screw nut drives the sliding block 15-3 to reciprocate linearly along the guide rail.

The control signal input end of the servo motor is connected with the control system, and the control system controls the start and stop. As shown in Figure 4, the servo motor is installed in the middle of the chassis frame, between the two lead screw electric slide rail devices. Two electromagnetic clutches 17-1 and 17-2 are respectively installed at the power input end of the two-screw electric slide rail device close to the center of the chassis. The gear reduction box is provided with a power input end (active bevel gear) and two power output ends (driven bevel gear), the output shaft of the servo motor is connected with the power input end of the gear reduction box, and the two powers of the gear reduction box The output ends are respectively connected with the power input ends of the two electromagnetic clutches, and the power output ends of the two electromagnetic clutches are connected with the corresponding screw shafts. Considering that the output shaft of the servo motor is perpendicular to the direction of the screw, the gear reducer uses bevel gears to transmit power. The control signal input ends of the two electromagnetic clutches are connected to the control system, and the control system controls the on and off respectively, that is, when the first/second electromagnetic clutch is disconnected, the power of the servo motor is only transmitted to the rear/front screw, and the The front two driving wheel legs implement separate two-wheel adjustment; when the two electromagnetic clutches are both connected, it is four-wheel synchronous adjustment.

The front and rear lead screw electric slide rail devices are equipped with grating rulers on the side to measure the stroke of their respective sliders on the track, which is connected with the control system to reflect the current wheelbase of the car body chassis.

The left and right driving wheel legs at the front of the car body 3 are each connected to the sliding block on the front screw electric slide rail device through a pair of connecting rod structure, and the left and right driving wheel legs at the rear of the car body are connected to each other through a pair of connecting rod structure. The sliding block connection on the rear screw electric slide rail device. As shown in Figures 4, 14, and 17, the connecting rod structure is composed of a rocker arm extension rod 13-1 and a driving connecting rod 13-2, one end of which is connected by a second rotating pair and a self-locking connector , The other end of the rocker arm extension rod 13-1 is fixedly connected to the rocker arm 7 for driving the rocker arm 7 to rotate around the rocker arm shaft 12, and the other end of the driving link 13-2 is connected to the corresponding The sliding block is hinged through the third rotating pair, which converts the linear motion of the sliding block into a rotating motion that drives the rocker arm extension rod 13-1 to rotate around the rocker shaft 12 as the center.

As shown in Figures 7 to 13, the self-locking connector includes components such as a first connecting block 13-3, a second connecting block 13-5, and a positioning pin electromagnet 13-4. A locking electromagnet 13-5-3 is mounted on the second connecting block 13-5. After the locking electromagnet 13-5-3 is energized, the two connecting blocks are connected by magnetic attraction. The first connecting block 13-3 is fixedly installed at the end of the rocker arm extension rod 13-2, and the second connecting block 13-5 is hinged with the driving link 13-1 through the second rotating pair; The connecting block 13-5 is provided with a waist-shaped limiting hole 13-5-2, the positioning pin electromagnet 13-4 is installed at the end of the driving link 13-1, and the end of the driving link 13-1 There is a circle of evenly distributed pin holes. When the locking electromagnet 13-5-3 loses power, the control system controls the positioning pin electromagnet 13-4 to move, and its extended pin passes through the pin of the drive connecting rod 13-1 The hole is inserted into the limiting hole 13-5-2 of the second connecting block 13-5 to prevent the second connecting block 13-5 from rotating freely.

After the locking electromagnet 13-5-3 loses power, the self-locking connector is disconnected, and the drive connecting rod 13-1 and the rocker arm extension rod 13-2 are disconnected, so that the four wheels are separated from the longitudinal axis of the car body. The wheelbase can be adjusted independently.

The second connecting block 13-5 is a convex block. As shown in FIG. 10, a convex structure is provided on the mating surface with the first connecting block. The rotating shaft 13-5-1 of the second rotating pair is installed on the second connecting block 13-5. The first connecting block 13-3 is a concave block, and its mating surface is provided with a groove structure adapted to the shape of the protruding structure, as shown in FIG. 11, the first connecting block 13-3 is also Two plug-in boards 13-3-2 are provided. The two plug-in boards 13-3-2 are located on the left and right sides of the groove structure, protruding from the mating surface of the first connecting block 13-3, and the second connecting block 13 -5 There are two suitable slots in the corresponding positions. When the first connecting block 13-3 and the second connecting block 13-5 are attracted by magnetic force, the protruding structure is embedded in the groove structure, and the plug-in board 13-3-2 is inserted into the slot. Based on the concave and convex structure and the plug-in board and slot structure, the two connecting blocks will not easily stagger in the direction perpendicular to the magnetic force under the adsorption state. The inner corners of the two plug-in boards 13-3-2 are chamfered, and the chamfered inclined surface 13-3-3 is used to face the convex structure, so that the two connecting blocks can be positioned quickly and accurately during the butting process.

At the same time, a pressure sensor 19 and a travel switch 20 are provided in the groove structure. The travel switch 20 is used to determine whether the first and second connecting blocks are connected in place, and the pressure sensor 19 is used to determine the reliability of the connection between the two. The signal output ends of the pressure sensor 19 and the travel switch 20 are connected to the control system. When the first and second connecting blocks are adsorbed, the protruding structure is embedded in the groove structure and can touch the pressure sensor 19 and travel switch 20. After the control system receives the signal sent by the travel switch 20 and the pressure sensor 19, it controls the electromagnetic clutch to be combined. When the data fed back by the pressure sensor 19 exceeds the preset threshold, the control system considers the connecting rod structure to be fixed Reliable, can start the servo motor to drive the slider.

The wheeled agricultural robot in this embodiment includes the following four wheelbase adjustment modes:

A) Four-wheel track synchronization adjustment mode: the first and second electromagnetic clutches and their respective locking connectors are in a combined state, and the driving device (18) synchronizes the track of the front and rear wheels through two linear slide devices;

B) Front wheel track independent adjustment mode: the first electromagnetic clutch and the respective locking connectors are in the combined state, the second electromagnetic clutch is disconnected, and the driving device (18) adjusts the track of the front wheels through the front linear slide device;

C) Rear wheel track independent adjustment mode: the second electromagnetic clutch and the respective locking connectors are in the combined state, the first electromagnetic clutch is disconnected, and the driving device (18) adjusts the track of the front wheels through the rear linear slide device;

D) Four-wheel position independent adjustment mode: the first and second electromagnetic clutches and their respective locking connectors are in a disconnected state, and the distance between the four wheels and the longitudinal axis of the car body can be adjusted independently;

Among them, A), B), C) are active adjustment modes, D) is passive adjustment mode, and the four modes A), B), C), and D) can be closed-loop automatic control or open-loop manual control .

Preferably, the agricultural robot in this embodiment can start the active adjustment mode of automatic control during the driving process, and its automatic wheelbase adjustment method specifically includes the following steps:

1) When the robot is traveling in the field, it uses three-dimensional lidar to scan the ground and crops in front, and uses the geographical position data of the vehicle body sent by the satellite positioning system and the chassis frame attitude data fed back by the inertial sensor to establish the basis of the geodetic coordinates. It is a three-dimensional point cloud map of the field scene of OXYZ, and then uses the RANSAC algorithm to fit a Hessian plane equation, and then refines and reconstructs the detection ground through the least squares fitting;

In the geodetic coordinate system, the vertical upward Z coordinate represents the height of the three-dimensional point from the ground, the X direction represents the longitudinal direction of the horizontal plane, that is, the direction in which the robot travels, and the Y direction represents the lateral direction of the horizontal plane, which is perpendicular to the X direction;

2) According to the type of crop and its growth stage, a reasonable crop height threshold is preset in the control system, and it is determined that the point where the height coordinate (z coordinate) of the three-dimensional point cloud of the field scene is greater than the height threshold is the crop row cluster So as to separate the crop row cluster point cloud from the point cloud diagram, calculate the midpoint of each crop row cluster, and the longitudinal line of the midpoint is regarded as the centerline of the crop row;

3) After obtaining the center line of each crop row, according to the current driving position of the robot body, the row spacing of each crop row in front of the car body is calculated in real time, combined with the position between the rows of the left and right wheels of the car body, or the number of rows crossed , Calculate the theoretical width of the front and rear two sets of wheels, that is, the target width of the track adjustment;

4) Obtain the actual width of the track, calculate the difference between the actual width of the track and the target width of the track adjustment. The control system is based on the control strategy (optimal control method or proportional-integral-derivative control method PID) that follows the change of the track of the crop. The corresponding control command is output to the linear slide rail device, and the rocker arm is rotated through a certain yaw angle through the movement of the slider, and the distance between the wheel and the longitudinal axis of the vehicle body is adjusted to match the distance between the crop rows in front of the vehicle body. When the yaw angle of the rocker arm is adjusted in place, the electric brake 21 at the rocker arm shaft is controlled to move so that the rocker arm shaft cannot rotate relative to the chassis frame to fix the wheel base.

Before implementing the automatic wheel track adjustment method, the wheel track adjustment threshold should be set. During the adjustment process, if the target track width requested for adjustment exceeds the threshold, the robot will stop moving for safety reasons, and the robot will stop moving forward. Adjust the wheelbase later. In this way, the connection stress between the rocker arm and the robot body can be minimized.

Regarding the passive adjustment mode D), the agricultural robot in this embodiment preferably adopts an open-loop manual wheel track adjustment method, which specifically includes the following steps:

1) The operator plans in advance the track adjustment amount of the driving wheel legs to be adjusted according to the terrain in front of the vehicle body or the crop row spacing, and based on the track adjustment amount, sends an adjustment instruction to the robot control system through the remote control terminal;

The remote control terminal is provided with a user interface for the operator to select an adjustment mode and input wheel track adjustment commands;

2) After sending the adjustment command, for the driving wheel leg to be adjusted, the control system first controls the locking electromagnet of the corresponding locking connector to lose power, so that the first connection block 13-3 and the second connection block 13-5 Lose the restriction of magnetic attraction, disconnect the drive connecting rod 13-1 and the rocker arm extension rod 13-2, and control the positioning pin solenoid 13-4 while the locking solenoid 13-5-3 loses power. Action to make the protruding pin inserted into the limiting hole of the second connecting block to limit the freedom of movement of the second connecting block and prevent the two connecting blocks from failing to be accurately butted in time when the slider is used to adjust the wheelbase;

Then, the control system controls the rotation of the servo motor to push the slider of each screw electric slide rail device to the initial position, so that the drive connecting rod is reset to the state of parallel to the screw, avoiding contact with other parts;

Secondly, the control system controls the first electromagnetic clutch and the second electromagnetic clutch to be disconnected at the same time, without participating in the adjustment of the wheelbase;

Finally, the control system outputs corresponding control commands to the hub motor 14 and the steering motor 8 to drive the wheels 10 to move around the rocker shaft 12. The forward or reverse motion of the wheels 10 will drive the rocker arm to yaw. The operator can control the terminal The instrument observes the turning angle of the rocker arm, or the vertical distance from the center of the wheel to the longitudinal axis of the car body collected by other sensing devices. The user interface displays the changes of the 4 wheel distance parameters in real time. When the yaw angle of the rocker arm is adjusted in place After that, the hub motor 14 stops rotating, and the electric brake immediately locks the rocker arm action and fixes the rocker arm shaft at a specific angle to achieve independent adjustment of the track of the wheel 10 (after the vehicle body is started, the steering motor 8 is used according to The next direction of travel controls the wheels to turn in place).

Passive adjustment mode D) is suitable for complex road conditions, when there are ditches, obstacles in the field, or when passing through a long and narrow aisle, so that the robot can pass smoothly. In the process of implementing the passive adjustment mode, before the user controls the wheel rotation, the control system can be operated, the four driving wheel legs can be adjusted independently, combined with the on-off control of the corresponding electromagnetic clutch and the locking electromagnet, or the servo motor and The lead screw electric slide rail device is implemented, but it is preferably operated by the above-mentioned manual wheel track adjustment method, and operated when the vehicle body is out of service.

In each adjustment mode, the control principle of the chassis track is as follows:

As shown in Figure 18, each of the four rocker arm shafts used for wheelbase adjustment is equipped with an absolute value encoder to measure the rotation angles α1, α2, α3, and α4 of the rocker arm relative to the longitudinal axis of the vehicle body. As shown in the figure, the center distance of the left and right rocker arm shafts is W1; the center distance of the front and rear rocker arm shafts is L1; the length of the track adjustment rocker arm is D (the horizontal distance between the rocker arm spindle and the upper shaft of the wheel leg bracket); then according to the rotary encoder From the angle measured in real time, the corresponding front wheel track W2 and rear wheel track W3 can be obtained. The calculation formula is as follows:

W2=W1+D·sin(α1)+D·sin(α2)

W3=W1+D·sin(α3)+D·sin(α4)

The corresponding front wheel track L2 and front wheel track L3, the calculation formula is as follows:

L2=L1+D·cos(α1)+D·cos(α2)

L3=L1+D·cos(α3)+D·cos(α4)

In the four-wheel synchronization control mode, the rotation angles of the rocker arm relative to the longitudinal axis of the vehicle body are all equal, that is, α1=α2=α3=α4, W2=W3.

In the front wheel track independent adjustment mode or the rear wheel track independent adjustment mode, the rotation angles of the two front wheel rocker arms relative to the longitudinal axis of the car body are equal, and the rotation angles of the two rear wheel rocker arms relative to the longitudinal axis of the car body are equal, that is, α1 =α2,α3=α4.

In special cases, in the four-wheel position independent adjustment mode, the rotation angle of the rocker arm relative to the longitudinal axis of the vehicle body is not equal.

Taking the active adjustment mode as an example, the agricultural robot uses 3D lidar to measure point cloud data such as crops and ground in front of the vehicle, and converts the point cloud to the ground coordinate system through the inertial attitude sensor and satellite positioning system, according to the position coordinates of the robot chassis. For adaptive track adjustment, the control system extracts the row spacing Wd between the two crop rows closest to the left and right wheels of the chassis based on the point cloud data, and then uses the difference between W2 and Wd, and the difference between W3 and Wd as the input of the control system. The output of the control system is the speed control command of the servo motor and the switching command of the two electromagnetic clutches. After the wheelbase is adjusted in place, the electric brake 21 on the rocker arm shaft is locked.

The control system of the agricultural robot of the present invention is equipped with a number of dedicated control units, including motor controllers, navigation control units, and work tool control units. In addition to the motor controllers connected through the CAN bus, different sensors and functional control units all pass Ethernet connection, and use TCP/IP for communication.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have With various changes and improvements, the scope of protection claimed by the present invention is defined by the appended claims, specification and their equivalents.

Claims

A wheeled agricultural robot with an adaptive wheel track adjustment function, comprising a control system and a vehicle body (3) provided with four driving wheel legs, and is characterized in that it is also provided with a track adjustment actuator;

The four driving wheel legs of the vehicle body (3) are each connected to the chassis frame through a corresponding rocker arm (7). The driving wheel legs include a wheel (10) and a steering device (8), each wheel (10) All are driven by an independent hub motor (14), and the drive circuit of the hub motor (14) is connected to the control system;

The steering device (8) includes a steering motor that controls the steering of the wheels (10) and a motor mounting seat. The motor mounting seat is connected to the lower wheel (10) through a wheel leg bracket (9); the outer side of the rocker arm (7) One end is fixedly connected to the motor mounting seat, and the inner end is connected to the chassis frame through a rotating pair including the rocker shaft (12), then the rocker arm (7) can be centered on the rocker shaft (12) relative to the longitudinal axis of the car body Lateral swing occurs, changing the distance from the corresponding wheel to the longitudinal axis of the car body;

The track adjustment actuator includes a driving device (18), a first electromagnetic clutch (17-1), a second electromagnetic clutch (17-2), and two front and rear linear slide devices. The two linear slide devices run along the car body. The longitudinal axis is laid and installed on the chassis frame, and its sliding blocks are all driven by the driving device (18) through a transmission mechanism, and the driving device (18) is a forward linear slide rail device through a first electromagnetic clutch (17-1) The slide block transmits power through the second electromagnetic clutch (17-2) to the slide block of the rear linear slide device. The drive device (18) and the control signal input terminals of the two electromagnetic clutches are respectively connected to the control system, The start-stop and on-off are controlled by the control system;

The left and right driving wheel legs at the front of the car body are each connected to the sliding block on the front linear slide device through a pair of linkage structure, and the left and right driving wheel legs at the rear of the car body are each connected to the rear linear slide device through a pair of linkage structure. The connecting rod structure is composed of a driving connecting rod (13-1) and a rocker arm extension rod (13-2), one end of which is connected by a rotating pair and a self-locking connector, and at the same time, the The other end of the rocker arm extension rod (13-1) is fixedly connected with the rocker arm (7) for driving the rocker arm (7) to rotate, and the other end of the driving link (13-1) is connected to the corresponding slider Through the pivot joint, the linear motion of the slider is converted into a rotary motion that drives the rocker arm extension rod (13-2) to rotate around the rocker shaft (12);

The self-locking connector is composed of a first connecting block (13-3), a second connecting block (13-5) and a positioning pin electromagnet (13-4); one of the connecting blocks is equipped with a locking electromagnet ( 13-5-3), after the locking electromagnet (13-5-3) is energized, the two connecting blocks are firmly connected by magnetic attraction, and the self-locking connector is in a combined state; the first connecting block (13-3) ) Is fixedly installed at the end of the rocker arm extension rod (13-2), the second connecting block (13-5) is connected to the driving connecting rod (13-1) through a rotating pair; the second connecting block (13-5) ) Is provided with a limit hole (13-5-2), the positioning pin electromagnet (13-4) is installed on the driving connecting rod (13-1); when the locking electromagnet (13-5-3) loses power, The first and second connecting blocks lose the magnetic restraint, the self-locking connector is disconnected, and the control system controls the positioning pin electromagnet (13-4) to act at the same time, and inserts its protruding pin into the second connecting block (13-5) ) In the limit hole (13-5-2) to prevent the second connecting block (13-5) from rotating freely;

The wheeled agricultural robot includes the following four wheelbase adjustment modes:

A) Four-wheel track synchronization adjustment mode: the first and second electromagnetic clutches and the respective locking connectors are in a combined state, and the driving device (18) synchronizes the track of the front and rear wheels through two linear slide devices;

B) Front wheel track independent adjustment mode: the first electromagnetic clutch and the respective locking connectors are in the combined state, the second electromagnetic clutch is disconnected, and the driving device (18) adjusts the track of the front wheels through the front linear slide device;

C) Rear wheel track independent adjustment mode: the second electromagnetic clutch and the respective locking connectors are in the combined state, the first electromagnetic clutch is disconnected, and the driving device (18) adjusts the track of the rear wheels through the rear linear slide device;

D) Four-wheel position independent adjustment mode: the first and second electromagnetic clutches and their respective locking connectors are disconnected, and the distance between the four wheels and the longitudinal axis of the car body can be adjusted independently without interference.

Among them, A), B), C) are active adjustment modes, which drive the rocker arm (7) to swing laterally by controlling the drive device (18); D) is a passive adjustment mode, which drives the corresponding wheels by individually controlling the rotation of the hub motor Forward or reverse, thereby driving the rocker arm (7) to swing laterally, changing the distance from the wheel to the longitudinal axis of the vehicle body.
The wheeled agricultural robot with adaptive wheel track adjustment function according to claim 1, characterized in that:

The second connecting block (13-5) is a convex block, and the mating surface with the first connecting block (13-3) is provided with a convex structure, and the first connecting block (13-3) is a concave block, which is butted A groove structure adapted to the shape of the protrusion structure is provided on the surface; a pressure sensor (19) and a travel switch (20) are arranged in the groove structure, and the pressure sensor (19) and the travel switch (20) are provided in the groove structure. The signal output terminal of) is connected to the control system. When the first and second connecting blocks are adsorbed, the convex structure is embedded in the groove structure and can touch the pressure sensor (19) and the travel switch (20). The sensor feedback signal is not less than the preset threshold, and the control system considers that the connecting rod structure is firmly fixed, and selects an appropriate active adjustment mode from modes A)-C) to start the corresponding slider.
The wheeled agricultural robot with adaptive wheel track adjustment function according to claim 2, characterized in that:

The first connecting block (13-3) is provided with two insert plates (13-3-2), and the two insert plates (13-3-2) are located on the left and right sides of the groove structure, protruding from The mating surface of the first connection block (13-3), and the second connection block (13-5) is provided with an adapted slot at a corresponding position;

When the first connection block (13-3) and the second connection block (13-5) are attracted by magnetic force, the plug-in board (13-3-2) of the first connection block (13-3) is stuck in the second connection block ( In the slot of 13-5), and the inner side of the two plug-in boards (13-3-2) is provided with a chamfered inclined surface (13-3-2) facing the protruding structure.
The wheeled agricultural robot with adaptive wheel track adjustment function according to claim 1, characterized in that:

The driving device (18) is a servo motor, and the linear slide device adopts a lead screw electric slide device. The servo motor is installed in the middle of the chassis frame and is located between the two lead screw electric slide devices; the two electromagnetic clutches are respectively Installed at the power input end of the two-screw electric slide rail device close to the center of the chassis, the output shaft of the servo motor is connected to the input shafts of the two electromagnetic clutches through the transmission mechanism, that is, the power is transmitted to the front and rear two wires through the two electromagnetic clutches. Bar electric slide rail device.
The wheeled agricultural robot with adaptive wheel track adjustment function according to claim 1, characterized in that: a grating ruler (16) is arranged on the side of the linear slide rail device for measuring the slide on the track The stroke is connected with the control system, and the control system realizes precise control of the wheelbase by controlling the stroke of the slider.
The wheeled agricultural robot with adaptive wheelbase adjustment function according to any one of claims 1 to 5, characterized in that it is provided with a navigation system, and the control system controls the execution of wheelbase adjustment according to the signal fed back by the navigation system Mechanism action

The navigation system includes a terrain detection sensor (6), a satellite positioning receiver (5) and an inertial sensor. The control system is based on terrain information detected by the terrain detection sensor, vehicle body position information received by the satellite positioning receiver, and feedback from the inertial sensor. The vehicle body posture information analyzes the position and row spacing of the crop rows in front of the vehicle body, and calculates the suitable wheel base adjustment amount to output the corresponding control signal to the wheel base adjustment actuator.
A manual wheel track adjustment method based on the wheeled agricultural robot described in any one of claims 1-6, applied to passive adjustment mode D), performed in a non-driving state of the vehicle body, characterized in that it comprises the following steps:

1) According to the terrain in front of the vehicle body or the distance between crop rows, plan the track adjustment amount of each driving wheel leg wheel in advance, and based on the track adjustment amount, the operator sends an adjustment instruction to the robot control system through the remote control terminal;

2) After receiving the adjustment command, the control system first controls the disconnection of each locking connector; then, the driving device that controls the wheel track adjustment actuator starts, pushing the slider on each linear slide device back to the initial position; secondly, the control The first and second electromagnetic clutches are disconnected at the same time, and finally the corresponding control commands are output to the hub motor (14) and the steering motor to drive the wheels (10) to move forward or backward around the rocker shaft (12) to change the wheels The vertical distance to the longitudinal axis of the vehicle body, when the wheels are adjusted in place, the hub motor (14) is controlled to stop, and the electric brake (21) at the rocker arm shaft is controlled to act immediately to fix the rocker arm.
An automatic wheel track adjustment method based on the wheeled agricultural robot of claim 6, applied to the active adjustment mode A), B) or C), characterized in that it comprises the following steps:

1) Install the 3D lidar as a terrain detection sensor on the front of the car body. During the driving of the agricultural robot, the 3D lidar is used to scan the ground and crops in front, and the geographical position data and inertia of the car body sent by the satellite positioning system The chassis frame attitude data fed back by the sensor establishes a field scene three-dimensional point cloud image based on the vehicle body, and converts the field scene three-dimensional point cloud image into a point cloud image based on the geodetic coordinate system OXYZ, where the vertical Z coordinate represents the three-dimensional point Ground clearance, the X direction represents the longitudinal direction of the horizontal plane, that is, the direction in which the robot is traveling, and the Y direction represents the horizontal direction perpendicular to the X direction on the horizontal plane;

2) According to the type of crop and its growth stage, set an appropriate crop height threshold, and determine that the point in the field scene 3D point cloud map with the height coordinate greater than the height threshold is the point of the crop row cluster, so that the crop row cluster points The cloud is separated from the three-dimensional point cloud diagram, and then the midpoint of each crop row cluster is calculated, and the longitudinal line of the midpoint is the centerline of the crop row;

3) After obtaining the center line of each crop row, according to the current position of the robot body, the row spacing of the crop in front of the car body is calculated in real time, combined with the position between the rows of the left and right wheels of the car body or the number of rows crossed, calculate the front and rear two The theoretical width of the set of wheels, that is, the target width of the track adjustment;

4) Obtain the actual width of the wheelbase, calculate the difference between the actual width of the wheelbase and the target width of the wheelbase adjustment. Based on the control strategy of the wheelbase following the change of the crop line, the control system outputs the corresponding control instructions to the linear slide device, and through sliding The movement of the block drives the rocker arm to rotate through a certain yaw angle, and adjusts the distance between the front and/or rear wheels and the longitudinal axis of the vehicle body to adapt it to the distance between the crop rows in front of the vehicle body.
The automatic wheel track adjustment method according to claim 8, characterized in that, in step 1), on the basis of the three-dimensional point cloud map of the field scene, the RANSAC algorithm is used to fit a Hessian plane equation, and the least squares Fitting refines and reconstructs the detection ground.