Miniature rice field weeding machine and flexible seedling avoiding and seedling row tracking control method and system

Abstract

The invention provides a miniature rice field weeding machine and a flexible seedling avoiding and seedling row tracking control method and system, and relates to the field of rice field mechanical weeding, and the miniature rice field weeding machine comprises a spiral driving type miniature weeding machine, a flexible curvature sensor, an attitude sensor and a steering control unit. The flexible curvature sensor is used for detecting the position of the seedling and outputting an analog voltage signal through collision to calculate a transverse distance; the attitude sensor measures the yaw angle of the weeding machine in real time; the steering control unit adjusts the rotating speed of the driving motors on the two sides based on the fuzzy controller, and differential steering or pivot steering is achieved. The method has the advantages of being low in cost, high in reliability and high in environmental adaptability, can stably work in a complex rice field environment, and provides a new solution for rice planting mechanization.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural machinery, and relates to a micro paddy field weeding machine, a flexible seedling avoidance and seedling row tracking control method and system. Background Art

[0002] Weeds in paddy fields are an important factor that cannot be ignored in affecting the normal growth of seedlings, directly affecting the yield and quality of rice. Mechanical weeding has advantages such as reducing environmental pollution, lowering production costs, and improving labor efficiency compared to manual weeding and chemical weeding.

[0003] Compared with large - scale mechanical weeding equipment, micro weeding machines have advantages such as small size, flexible movement, and low seedling injury rate. At the same time, they adopt a walking method driven by a screw, which can not only overcome the driving difficulties such as easy subsidence and easy slipping of traditional wheeled and tracked vehicles, but also continuously stir the paddy field soil and water layer, effectively increasing the turbidity of the paddy field water layer and inhibiting weeds from carrying out photosynthesis. Due to the agronomic characteristics of rice planting, the weeding machine needs to ensure stable operation between rows and avoid rolling on both sides of the seedlings.

[0004] However, traditional micro weeding machines usually lack an effective seedling avoidance function and are prone to rolling on seedlings, resulting in crop damage. At the same time, traditional weeding machines mostly rely on image processing or positioning and navigation technologies for path planning, but these methods are easily interfered with in wet, soft, and muddy paddy field environments, resulting in a decrease in accuracy, making it difficult to implement the existing automatic seedling row tracking control technology in complex paddy field environments. Moreover, the control system based on image processing or high - precision positioning and navigation requires expensive hardware and complex computing resources, which instead increases the equipment cost.

[0005] It is necessary to propose a seedling avoidance and seedling row tracking technology to control the weeding machine to automatically drive between rows.

[0006] Therefore, how to provide a micro paddy field weeding machine, a flexible seedling avoidance and seedling row tracking control method and system with both high stability and low cost is an urgent problem for those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention proposes a micro paddy field weeding machine, a flexible seedling avoidance and seedling row tracking control method and system, which realize the flexible seedling avoidance and seedling row tracking functions of the micro weeding machine through a low - cost and high - reliability design.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention discloses a micro paddy field weeding machine, including: a weeding machine frame, screw drive wheels, flexible curvature sensors, attitude sensors, and a steering control unit; wherein,

[0010] There are two of the spiral drive wheels, which are arranged on both sides of the bottom of the weeding machine frame. The spiral drive wheels are provided with spiral blades.

[0011] There are two of the flexible bending sensors, which are transversely arranged at the front end of the weeding machine frame and are used to respectively touch the two sides of the seedling rows to generate bending deformation and then output voltage signals; the lengths of the two flexible bending sensors are the same.

[0012] The attitude sensor is installed at the centroid of the micro paddy field weeding machine and is used to measure and output the yaw angle signal in real time.

[0013] The steering control unit is used to receive the voltage signal and the yaw angle signal in real time, and control the steering and / or rotation speed of the spiral drive wheels according to the flexible seedling avoidance and seedling row tracking strategy, and correct the target path deviation of the weeding machine in real time.

[0014] Preferably, the spiral drive wheels are hollow spiral drive wheels, and the spiral directions of the spiral blades on the two sides of the spiral drive wheels are opposite.

[0015] Preferably, one end of the flexible bending sensor is fixed at the same height position at the front end of the weeding machine frame, and the other end extends along the X axis to the outer side of the weeding machine frame. The X axis is perpendicular to the forward direction Y axis of the micro paddy field weeding machine, and the two flexible bending sensors are respectively arranged along the positive and negative directions of the X axis.

[0016] The present invention also discloses a flexible seedling avoidance and seedling row tracking control method for the micro paddy field weeding machine according to the above, including the following steps:

[0017] S1: Obtain the voltage signals v 1 、v 2 of the two flexible bending sensors on both sides of the micro paddy field weeding machine during the process of traveling between the seedling rows in real time, and calculate the lateral distances x 1 、x 2 from the centroid of the micro paddy field weeding machine to the collision positions on both sides according to the preset fitting curve equation, and then output the lateral deviation d between the centroid of the micro paddy field weeding machine and the center line between the two sides of the seedling rows.

[0018] S2: Convert the lateral deviation into an angular deviation, that is, the angular deviation amount δ between the line connecting the centroid of the micro paddy field weeding machine to the collision position on the deviation side and the Y axis. The angular deviation amount δ is the preview heading angle.

[0019] S3: Obtain the yaw angle signal of the attitude sensor of the micro paddy field weeding machine during the process of traveling between the seedling rows in real time, and judge whether the absolute value range of the yaw angle signal is less than the preview heading angle δ by β; if not, enter S4, if so, enter S5.

[0020] S4: Control the two spiral drive wheels to rotate in the same direction, so that the spiral drive wheels make a rotational movement in place around the rotation center until the yaw angle signal is less than the absolute value range β, and then enter S5;

[0021] S5: Based on the magnitude relationship between the preview course angle δ and 0°, control the two spiral drive wheels to rotate in opposite directions, and calculate the rotational speed difference between the two spiral drive wheels according to the differential principle to achieve the adjustment of the rotational speed of the spiral drive wheels until the micro paddy field weeding machine travels along the center line between the two rows of seedlings.

[0022] Preferably, the preset fitting curve equation in S1 is the curve equation of the output voltage signal v of the flexible curvature sensor and the lateral distance x from the centroid of the micro paddy field weeding machine to the collision positions on both sides, obtained by fitting according to historical data; the lateral deviation

[0023] Preferably, in S3, the calculation steps of the absolute value range β of the preview course angle δ include:

[0024] S31: Calibrate the maximum value in the lateral distances x 1 , x 2 with the length value of the curvature sensor;

[0025] S32: Take as the lateral deviation d between the centroid of the micro paddy field weeding machine and the center line between the two rows of seedlings, and calculate the extreme value of the angle deviation amount δ:

[0026]

[0027] where l is the longitudinal distance from the intersection of the center line of the seedling row and the X-axis where the flexible curvature sensor is located to the centroid of the micro paddy field weeding machine;

[0028] S33: Determine the absolute value range β as [-δ m , δ m .

[0029] Preferably, S4 includes:

[0030] If the yaw angle signal ya is negative, control the two spiral drive wheels to rotate clockwise at the same time;

[0031] If the yaw angle signal ya is positive, control the two spiral drive wheels to rotate counterclockwise at the same time;

[0032] The expression is:

[0033]

[0034] w 1 is the rotational speed of the spiral drive wheel close to the negative X-axis, w2 is the rotational speed of the right spiral wheel near the positive X-axis direction, w 0 is the initial rotational speed of the spiral drive wheel, and the spiral directions of the spiral blades on both spiral drive wheels are opposite.

[0035] Preferably, the steps of implementing the in-situ rotational movement of the spiral drive wheel around the rotation center in the S4 include:

[0036] Set an incremental PI speed controller for adjusting the rotational speed of the spiral drive wheel;

[0037] Obtain the real-time rotational speed of the spiral drive wheel, and based on the incremental PI speed controller, calculate and control the torque current signal of the spiral drive wheel using the real-time rotational speed and the rotational speed difference Δw.

[0038] Preferably, the S5 includes:

[0039] If the preview course angle δ is equal to 0, control the spiral drive wheel to maintain the original speed;

[0040] If the preview course angle δ is greater than 0, change the rotational speed of the spiral drive wheel to deflect the micro paddy field weeding machine towards the negative X-axis direction. If the preview course angle δ is less than 0, change the rotational speed of the spiral drive wheel to deflect the micro paddy field weeding machine towards the positive X-axis direction. The expression is:

[0041]

[0042] In the formula, w 1 is the rotational speed of the spiral drive wheel near the negative X-axis direction, w 2 is the rotational speed of the right spiral wheel near the positive X-axis direction, w 0 is the initial rotational speed of the spiral drive wheel, Δw is the rotational speed difference between the two spiral drive wheels, and the spiral directions of the spiral blades on both spiral drive wheels are opposite.

[0043] Preferably, the steps of calculating the rotational speed difference between the two spiral drive wheels according to the differential principle in the S5 include:

[0044] Construct a fuzzy controller with the preview course angle δ as the input quantity and the rotational speed difference Δω between the two spiral drive wheels as the output quantity;

[0045] The fuzzy controller calculates the rotational speed difference Δw according to the quantization level correspondence between the preview course angle δ and the rotational speed difference Δw.

[0046] The present invention also discloses a flexible seedling avoidance and seedling row tracking control system according to the flexible seedling avoidance and seedling row tracking control method described above, including: a flexible bending degree sensor voltage signal processing unit, an attitude sensor yaw angle signal processing unit. Among them,

[0047] The voltage signal processing unit of the flexible bending sensor is used to obtain the voltage signals v 1 and v 2 of the flexible bending sensors on both sides in real time during the process of the micro paddy weeding machine moving between the seedlings, and calculates the lateral distances x 1 and x 2 from the centroid of the micro paddy weeding machine to the collision positions on both sides according to the preset fitting curve equation, and then outputs the lateral deviation d between the centroid of the micro paddy weeding machine and the center lines of the rows of seedlings on both sides; converts the lateral deviation into an angular deviation, that is, the angular deviation amount δ between the line connecting the centroid of the micro paddy weeding machine to the collision position on the deviation side and the Y axis, and the angular deviation amount δ is the preview course angle;

[0048] The yaw angle signal processing unit of the attitude sensor is used to obtain the yaw angle signal of the attitude sensor in real time during the process of the micro paddy weeding machine moving between the seedlings, and determines whether the yaw angle signal is less than the absolute value range β of the preview course angle δ; if not, outputs the control for the two spiral drive wheels to rotate in the same direction, which is used to make the spiral drive wheels rotate in place around the rotation center until the yaw angle signal is less than the absolute value range β; if so, based on the size relationship between the preview course angle δ and 0°, outputs the control instruction for the two spiral drive wheels to rotate in the opposite direction, and calculates the rotational speed difference between the two spiral drive wheels according to the differential principle, which is used to adjust the rotational speeds of the spiral drive wheels until the micro paddy weeding machine travels along the center lines of the rows of seedlings on both sides.

[0049] As can be seen from the above technical solutions, compared with the prior art, the beneficial effects of the present invention include:

[0050] By introducing a flexible bending sensor and an attitude sensor, and combining a fuzzy controller and a differential steering strategy, the present invention realizes the functions of flexible seedling avoidance and automatic seedling row tracking of the micro weeding machine.

[0051] The method proposed by the present invention mainly uses a flexible bending sensor to directly sense the position of the seedlings, avoiding the dependence on complex vision algorithms. The system is insensitive to factors such as ambient light and soil humidity, and has lower cost and stronger environmental adaptability compared with image processing and positioning navigation.

[0052] Through the fuzzy controller and the incremental PI speed controller, the present invention realizes intelligent path planning and real-time adjustment. The user only needs to drive the weeding machine to the target starting point, and the seedling row tracking and seedling avoidance operations can be automatically completed, enabling the weeding machine to stably travel in the complex ground environment of the paddy field, significantly improving the operation efficiency. The adopted spiral drive wheels have good driving performance compared with traditional crawler and wheel drive wheels. Description of the Drawings

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings;

[0054] Figure 1 It is the effect diagram of flexible seedling avoidance and seedling row tracking of the micro weeding machine provided by the embodiment of the present invention;

[0055] Figure 2 It is the schematic diagram of the principle of flexible seedling avoidance and seedling row tracking of the micro weeding machine provided by the embodiment of the present invention;

[0056] Figure 3 It is the flow chart of the control method for flexible seedling avoidance and seedling row tracking of the micro weeding machine provided by the embodiment of the present invention;

[0057] Figure 4 It is the schematic diagram of the control structure for flexible seedling avoidance and seedling row tracking of the micro weeding machine provided by the embodiment of the present invention;

[0058] In the figure:

[0059] 1 is the seedling; 2 is the weeding machine frame; 3 is the spiral drive wheel; 4 is the flexible bending sensor; 5 is the control box; point O is the centroid of the micro paddy field weeding machine; ICR is the actual differential steering rotation center of the micro paddy field weeding machine; B is the center distance between the left and right spiral wheels of the micro paddy field weeding machine; R is the actual differential rotation radius of the micro paddy field weeding machine; Vc is the longitudinal forward speed at the centroid of the micro paddy field weeding machine; V l 、V r are the actual speeds of the left and right spiral drive wheels considering the slip ratio respectively; Q is the center line of the alignment of the seedlings on both sides; d is the lateral distance between the alignment center line and the centroid of the micro paddy field weeding machine; x 1 、x 2 are the lateral distances between the positions of the real-time acquisition devices of the left and right bending sensors and the centroid of the micro paddy field weeding machine respectively; δ is the preview course angle; l is the longitudinal distance from the bending sensor to the centroid of the micro paddy field weeding machine; θ is the steering angle of the micro paddy field weeding machine. Detailed implementation manners

[0060] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0061] In the first aspect of the embodiment of the present invention, a micro paddy field weeding machine is provided, including: a weeding machine frame 2, spiral drive wheels 3, flexible curvature sensors 4, an attitude sensor, and a steering control unit; wherein,

[0062] There are two spiral drive wheels 3, which are arranged on both sides of the bottom of the weeding machine frame 2, and the spiral drive wheels 3 are provided with spiral blades; there are two flexible curvature sensors 4, which are horizontally arranged at the front end of the weeding machine frame 2, and are used to respectively touch the seedling rows of the seedlings 1 on both sides to generate a bending deformation and then output a voltage signal; the lengths of the two flexible curvature sensors 4 are the same; the attitude sensor is installed at the centroid of the micro paddy field weeding machine and is used to measure and output a yaw angle signal in real time; the steering control unit is used to receive the voltage signal and the yaw angle signal in real time, and control the steering and / or rotation speed of the spiral drive wheels according to the flexible seedling avoidance and seedling row tracking strategy, and correct the target path deviation of the weeding machine in real time.

[0063] As Figure 1 shown, the micro paddy field weeding machine walks between two rows of seedlings 1, and the flexible curvature sensors 4 extend horizontally to both sides of the micro paddy field weeding machine. The function is to sense whether the weeding machine touches the seedlings during the traveling process and estimate the lateral distance between the seedlings and the centroid of the weeding machine. The core principle of the flexible curvature sensor is based on the change of internal resistance or capacitance of the material caused by physical deformation. For a resistance change type flexible curvature sensor, when the sensor is bent, the internal resistance value will change with the change of the bending angle. The larger the bending angle, the more obvious the resistance change, and the sensor converts this resistance change into an analog voltage signal output. When the weeding machine is running, the flexible curvature sensor may collide slightly with the seedlings. The collision will cause the sensor to bend, and its internal resistance or capacitance will change accordingly.

[0064] In one embodiment, the spiral drive wheels are hollow spiral drive wheels, and the spiral directions of the spiral blades on both sides of the spiral drive wheels are opposite. During the traveling process of the micro weeding machine, the soil is turned and stirred by the spiral drive components, which not only destroys the roots of weeds, improves the turbidity of the paddy field water layer, inhibits the photosynthesis of weeds, but also improves the stability and passability of the weeding machine's self-traveling along the seedling row, and avoids rolling the seedlings.

[0065] In one embodiment, one end of the flexible curvature sensor is fixed at the same height position at the front end of the weeding machine frame, and the other end extends along the X-axis direction to the outer side of the weeding machine frame. The X-axis direction is perpendicular to the forward direction Y-axis of the micro paddy field weeding machine, and the two flexible curvature sensors are respectively arranged along the positive and negative directions of the X-axis.

[0066] In one embodiment, as Figure 1As shown in the figure, a control box is provided on the weeding machine frame for installing a steering control unit. The steering control unit mainly includes a main controller, a brushless DC drive motor with a built-in rotational speed sensor, and a brushless motor speed governor. The main controller is used to receive voltage signals and yaw angle signals in real time, and send instructions to the brushless motor speed governor to control the steering and / or rotational speed of the brushless DC drive motor according to the flexible seedling avoidance and seedling row tracking strategy, and correct the target path deviation of the weeding machine in real time.

[0067] The second aspect of the embodiment of the present invention also discloses a flexible seedling avoidance and seedling row tracking control method for a micro paddy field weeding machine according to the first aspect of the embodiment, as Figure 2 shown in the parameters, including the following steps:

[0068] S1: Set the target rotational speeds w 0 of the two side spiral drive wheels, initialize the sensor data, start the automatic seedling row tracking operation of the weeding machine, and obtain the voltage signals v 1 、v 2 of the two side flexible curvature sensors in real time during the process of the micro paddy field weeding machine moving between the seedling rows, and calculate the lateral distances x 1 、x 2 from the centroid of the micro paddy field weeding machine to the collision positions on both sides according to the preset fitting curve equation, and then output the lateral deviation d between the centroid of the micro paddy field weeding machine and the center line of the seedling rows on both sides;

[0069] S2: Convert the lateral deviation into an angular deviation, that is, the angular deviation amount δ between the line connecting the centroid of the micro paddy field weeding machine to the collision position on the deviation side and the Y axis. The angular deviation amount δ is the preview course angle;

[0070] S3: Obtain the yaw angle signal of the attitude sensor in real time during the process of the micro paddy field weeding machine moving between the seedling rows, and judge whether the yaw angle signal is less than the absolute value range β of the preview course angle δ; if not, enter S4, if so, enter S5;

[0071] S4: Control the two spiral drive wheels to rotate in the same direction to realize the in-situ rotation movement of the spiral drive wheels around the rotation center until the yaw angle signal is less than the absolute value range β, and then enter S5;

[0072] S5: Based on the size relationship between the preview course angle δ and 0°, control the two spiral drive wheels to rotate in the opposite direction, and calculate the rotational speed difference between the two spiral drive wheels according to the differential principle to realize the rotational speed adjustment of the spiral drive wheels until the micro paddy field weeding machine moves along the center line of the seedling rows on both sides.

[0073] It should be noted that the realization of flexible seedling avoidance and seedling row tracking of the weeding machine mainly includes two major parts: measuring the analog voltage signal of the flexible curvature sensor for calculation to preview the heading angle, and processing the yaw angle output by the attitude sensor for data analysis to output the target rotational speed of the spiral wheel and the rotational speed of the driving motor controlled by the steering control unit. When the flexible curvature sensor collides with the seedlings and the weeding machine generates a large-angle deflection during the operation between the rows of the weeding machine, the target rotational speed for the next moment is sent to the steering control unit to correct the target path deviation of the weeding machine in real time and avoid crushing the seedlings.

[0074] In one embodiment, the preset fitting curve equation in S1 is the curve equation of the output voltage signal v of the flexible curvature sensor and the lateral distance x from the centroid of the micro paddy weeding machine to the collision positions on both sides, which is obtained by fitting based on historical data.

[0075] During specific implementation, set the target stable driving speed, conduct multiple groups of collision tests at different positions of the curvature sensor during the driving process of the weeding robot, calibrate and fit the curve equation of the output voltage signal of the curvature sensor and the lateral distance, such as x = a*v + b.

[0076] In this embodiment, the lateral deviation

[0077] In one embodiment, in S1, the signals of the flexible curvature sensors on the left and right sides are read periodically (10 ms), and after median filtering, the lowest analog voltage value v at the moment of detachment during the collision process between the sensor and the seedlings is obtained. 1 、v 2 。

[0078] In one embodiment, in S3, the signal of the attitude sensor at the centroid of the micro weeding machine is read, and after low-pass filtering, the yaw angle ya of the weeding machine is obtained; the signal of the internal rotational speed sensor of the brushless DC driving motor is read, and the rotational speed information of the rotor is obtained through the CAN bus and processed to solve the rotational speeds w 1 ′、w 2 ′ of the two spiral wheels.

[0079] In one embodiment, when the micro weeding machine deflects, one side sensor may hit the seedlings while the other side does not send a collision signal. When the flexible curvature sensor at the impact point generates the maximum bend, the lateral distance d is the maximum value at this time, and the corresponding preview heading angle δ is the extreme value β that the sensor can calculate. In S3, the calculation steps for the absolute value range β of the preview heading angle δ include:

[0080] S31: Calibrate the maximum value in the lateral distances x 1 、x 2 with the length value of the curvature sensor;

[0081] S32: With As the lateral deviation d between the centroid of the micro paddy field weeding machine and the center line of the seedling rows on both sides, calculate the extreme value of the angular deviation δ:

[0082]

[0083] In the formula, l is the longitudinal distance from the intersection of the center line of the seedling row and the X-axis where the flexible curvature sensor is located to the centroid of the micro paddy field weeding machine; the density and weight of each part of the weeding machine are assigned in the 3D modeling software, and the coordinates at the centroid can be obtained in the mass properties, so as to measure the longitudinal distance between the installation position of the bending sensor and the centroid;

[0084] In this step, it can be understood that when the micro paddy field weeding machine deviates between two seedling rows to a state where the end of one side flexible curvature sensor just touches the corresponding side seedling row and outputs a voltage signal, further deviation of this side will result in no voltage signal output. Taking this state as the limit state for calculating the extreme value of the angular deviation δ, the calculated value of the lateral distance x on this side is the length value of the flexible curvature sensor.

[0085] S33: Determine the absolute value range β as [-δ m , δ m .

[0086] In the real-time calculation process of the preview course angle δ, it is also calculated based on the geometric relationship and obtained. From the value of δ, the driving state of the current weeding machine between the seedling rows is deduced.

[0087] When |ya| ≤ |β|, it means that the flexible bending sensors on both sides of the weeding machine hit the seedlings, and the spiral drive wheels on both sides of the weeding machine realize steering adjustment according to the differential principle and enter S5; when |ya| > |β|, it means that at this moment, the weeding machine is deflected at a large angle due to unstable factors on the paddy field ground, and the spiral drive wheels on both sides are controlled to rotate in the same direction to realize in-situ steering and enter S4.

[0088] In one embodiment, for the complex paddy field road surface environment, the driving direction of the weeding machine may be deflected greatly, resulting in |ya| > |β|. For this situation, S4 includes:

[0089] If the yaw angle signal ya is negative, control the spiral drive wheels on both sides to rotate clockwise at the same time;

[0090] If the yaw angle signal ya is positive, control the spiral drive wheels on both sides to rotate counterclockwise at the same time;

[0091] The expression is:

[0092]

[0093] w 1is the rotational speed of the spiral drive wheel near the negative X-axis, w 2 is the rotational speed of the right spiral wheel near the positive X-axis, w 0 is the initial rotational speed of the spiral drive wheel, and the spiral directions of the spiral blades on both sides of the spiral drive wheel are opposite.

[0094] As Figure 3 shown, under wet and soft ground conditions, the axial force directions generated by the same-direction rotation of the two spiral wheels are opposite and act on the spiral wheel axis, making the resultant force on the weeding machine a steering moment, so that the weeding machine rotates around the rotation center. When ya is negative, the weeding machine has a large right deflection, and the two spiral wheels rotate clockwise at the same time, and the weeding machine realizes counterclockwise rotation in place until δ > -δ m ; when ya is positive, the weeding machine has a large left deflection, and the two spiral wheels rotate counterclockwise at the same time, and the weeding machine realizes clockwise rotation in place until δ < δ m .

[0095] In one embodiment, the steps of realizing the in-place rotation movement of the spiral drive wheel around the rotation center in S4 include:

[0096] Set an incremental PI speed controller for adjusting the rotational speed of the spiral drive wheel;

[0097] Obtain the real-time rotational speed of the spiral drive wheel, and based on the incremental PI speed controller, calculate and control the torque current signal of the spiral drive wheel by using the real-time rotational speed and the rotational speed difference Δw.

[0098] When specifically executing, as Figure 4 shown, the spiral drive wheel rotates forward on the surface of paddy field silt and will be subject to a large driving resistance. Therefore, to ensure that the rotational speeds of the two spiral wheels are stable near the target rotational speed value, an incremental PI speed controller is set to adjust the motor speed. The real-time rotational speed of the motor rotor is obtained by using the rotational speed sensor built in the brushless DC drive motor, and the rotational speed of the output rotating shaft is solved by dividing by the reduction ratio. The torque current signal for controlling the motor speed is calculated according to the deviation between the actual feedback rotational speed and the target rotational speed. Among them, the PI speed controller in this design takes the difference between the rotational speed of the output rotating shaft fed back by the electronic speed control CAN bus message and the target spiral wheel rotational speed as the input, and takes the sum of the proportional and integral parts accumulated by the controller in real time as the torque current value output. The rotational speed sampling period is set to 10 milliseconds. In each sampling period, first calculate the rotational speed deviation and update the integral part value, use the difference between the current deviation and the previous deviation as the proportional part input, accumulate the integral part and the proportional part as the incremental PI controller current value output, and limit the output current value to prevent the motor from being burned out due to excessive current. Finally, update the deviation storage, and use the current deviation value as the previous deviation in the next sampling period. The corresponding PID controller parameters Kp and Ki are 0.70 and 0.03 respectively.

[0099] In one embodiment, S5 includes:

[0100] If the preview heading angle δ is equal to 0, it means that the bending sensors on both sides of the weeding machine do not hit the seedlings or the current centroid of the weeding machine is on the center line of the seedling row, and the spiral drive wheels are controlled to maintain the original speed; if δ is greater than or less than 0, it means that the weeding machine deviates from the center line of the seedling row at this moment, and the rotational speeds of the two spiral wheels need to be changed according to the magnitude of the δ value. Specifically:

[0101] If the preview heading angle δ is greater than 0, the rotational speed of the spiral drive wheels is changed to deflect the micro paddy field weeding machine in the negative direction of the X-axis; if the preview heading angle δ is less than 0, the rotational speed of the spiral drive wheels is changed to deflect the micro paddy field weeding machine in the positive direction of the X-axis. The expression is:

[0102]

[0103] In the formula, w 1 is the rotational speed of the spiral drive wheel close to the negative direction of the X-axis, w 2 is the rotational speed of the right spiral wheel close to the positive direction of the X-axis, w 0 is the initial rotational speed of the spiral drive wheels, Δw is the rotational speed difference between the two spiral drive wheels, and the spiral directions of the spiral blades on the two spiral drive wheels are opposite.

[0104] During specific execution, as Figure 2 shown, when δ < 0, x 2 < x 1 , the right bending sensor of the weeding machine hits the seedlings, that is, the driving direction deflects to the right. Therefore, the rotational speed of the right spiral drive wheel should be appropriately increased, and the rotational speed of the other spiral wheel remains unchanged, so as to increase the right propulsion force to prompt the weeding machine to adjust its heading to the left. At the same time, the absolute value of the output rotational speed difference increases with the increase of the absolute value of the preview heading angle δ; when δ > 0, x 2 > x 1 , the left bending sensor of the weeding machine hits the seedlings, that is, the driving direction deflects to the left. Therefore, the rotational speed of the left spiral drive wheel should be appropriately increased, and the rotational speed of the other spiral wheel remains unchanged, increasing the left propulsion force to prompt the weeding machine to adjust its heading to the right; at the same time, the absolute value of the output rotational speed difference increases with the increase of the absolute value of the preview heading angle δ.

[0105] In one embodiment, the steps of calculating the rotational speed difference between the two spiral drive wheels according to the differential principle in S5 include:

[0106] Construct a fuzzy controller with the preview heading angle δ as the input quantity and the rotational speed difference Δω between the two spiral drive wheels as the output quantity;

[0107] The fuzzy controller calculates the rotational speed difference Δw according to the corresponding relationship between the quantization levels of the preview heading angle δ and the rotational speed difference Δw.

[0108] In this embodiment, the quantization levels of the preview course angle δ are divided into 7 levels, namely, large negative, medium negative, small negative, zero, small positive, medium positive, and large positive, which are represented by NB, NM, NS, Z, PS, PM, and PB respectively; the basic domain of the rotational speed difference Δw is set as [-210 rpm, 210 rpm], and the quantization levels of the rotational speed difference are divided into 7 levels, namely, large negative, medium negative, small negative, zero, small positive, medium positive, and large positive, which are represented by NB, NM, NS, Z, PS, PM, and PB respectively.

[0109] The present invention also discloses a flexible seedling avoidance and seedling row tracking control system according to a flexible seedling avoidance and seedling row tracking control method, including: a flexible curvature sensor voltage signal processing unit, an attitude sensor yaw angle signal processing unit. Among them,

[0110] The flexible curvature sensor voltage signal processing unit is used to obtain in real time the voltage signals v 1 、v 2 of the flexible curvature sensors on both sides during the process of the micro paddy weeding machine moving between the seedling rows, and calculate the lateral distances x 1 、x 2 from the centroid of the micro paddy weeding machine to the collision positions on both sides according to the preset fitting curve equation, and then output the lateral deviation d between the centroid of the micro paddy weeding machine and the center line between the seedling rows on both sides; convert the lateral deviation into an angular deviation, that is, the angular deviation amount δ between the line connecting the centroid of the micro paddy weeding machine to the collision position on the deviation side and the Y axis. The angular deviation amount δ is the preview course angle;

[0111] The attitude sensor yaw angle signal processing unit is used to obtain in real time the yaw angle signal of the attitude sensor during the process of the micro paddy weeding machine moving between the seedling rows, and judge whether the yaw angle signal is less than the absolute value range β of the preview course angle δ; if not, output the control for the two spiral drive wheels to rotate in the same direction, so as to make the spiral drive wheels rotate in place around the rotation center until the yaw angle signal is less than the absolute value range β; if so, based on the magnitude relationship between the preview course angle δ and 0°, output the control instruction for the two spiral drive wheels to rotate in the opposite direction, and calculate the rotational speed difference of the two spiral drive wheels according to the differential principle, so as to adjust the rotational speeds of the spiral drive wheels until the micro paddy weeding machine travels along the center line between the seedling rows on both sides.

[0112] The above has introduced in detail the micro paddy weeding machine and the flexible seedling avoidance and seedling row tracking control method and system provided by the present invention. In this embodiment, specific examples are used to elaborate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

[0113] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to these embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A miniature rice field weeder, characterized in that: include: A lawn mower frame, a spiral drive wheel, a flexible bending sensor, a posture sensor and a steering control unit; wherein, There are two spiral drive wheels, which are arranged on both sides of the bottom of the weeder frame, and the spiral drive wheels are provided with spiral blades; There are two flexible bending sensors, which are horizontally arranged at the front end of the weeder frame and are used to touch the seedling rows on both sides to generate bending deformation and output voltage signals; the two flexible bending sensors have the same length; The attitude sensor is installed at the center of mass of the miniature rice field weeder and is used to measure and output a yaw angle signal in real time; The steering control unit is used to receive the voltage signal and the yaw angle signal in real time, and control the steering and / or rotation speed of the spiral drive wheel according to the flexible seedling avoidance and seedling row tracking strategy, so as to correct the target path deviation of the weeder in real time.

2. The mini rice field weeder according to claim 1, characterized in that: One end of the flexible curvature sensor is fixed at the same height position at the front end of the weeder frame, and the other end extends toward the outer side of the weeder frame along the X-axis, the X-axis is perpendicular to the Y-axis direction of the forward direction of the mini rice field weeder, and the two flexible curvature sensors are respectively extended along the positive and negative directions of the X-axis.

3. A flexible seedling avoidance and seedling row tracking control method of a miniature rice field weeder according to claim 1, characterized in that: The steps include: S1: Real-time acquisition of voltage signals v1 and v2 of flexible curvature sensors on both sides of the micro-rice field weeder during its movement between seedling rows, and calculation of lateral distances x1 and x2 from the centroid of the micro-rice field weeder to the collision positions on both sides according to a preset fitting curve equation, and then output of lateral deviation d between the centroid of the micro-rice field weeder and the center line of the seedling rows on both sides; S2: converting the lateral deviation into an angular deviation, that is, an angular deviation δ between a line connecting the center of mass of the mini rice field weeder to the collision position on the deviation side and the Y-axis, wherein the angular deviation δ is a pre-aiming heading angle; S3: acquiring in real time the yaw angle signal of the attitude sensor of the mini rice field weeder during its movement between seedling rows, and judging whether the yaw angle signal is less than the absolute value range of the pre-aiming heading angle δ is β; if not, entering S4, and if so, entering S5; S4: Control the two spiral drive wheels to rotate in the same direction, so that the spiral drive wheels rotate in situ around the rotation center until the yaw angle signal is less than the absolute value range β, and enter S5; S5: Based on the relationship between the pre-aiming heading angle δ and 0°, the two spiral drive wheels are controlled to rotate in opposite directions, and the speed difference between the two spiral drive wheels is calculated according to the differential principle to adjust the speed of the spiral drive wheels until the micro rice field weeder moves along the center line between the rows of seedlings on both sides.

4. A flexible seedling avoidance and seedling row tracking control method according to claim 3, characterized in that: The preset fitting curve equation in S1 is a curve equation of the output voltage signal v of the flexible curvature sensor and the lateral distance x from the center of mass of the micro rice field weeder to the collision position on both sides obtained by fitting historical data; 5. The flexible seedling avoidance and seedling row tracking control method according to claim 3 is characterized in that: In S3, the step of calculating the absolute value range β of the preview heading angle δ includes: S31: Calibrate the maximum value x of the lateral distances x1 and x2 using the length value of the curvature sensor max ; S32: As the lateral deviation d between the center of mass of the micro rice field weeder and the center line of the rice seedling rows on both sides, the extreme value of the angle deviation δ is calculated: Wherein, l is the longitudinal distance from the intersection of the center line of the seedling row and the X-axis direction where the flexible curvature sensor is located to the center of mass of the micro rice field weeder; S33: Determine the absolute value range β as [-δ m ,δ m ].

6. A flexible seedling avoidance and seedling row tracking control method according to claim 3, characterized in that: The S4 includes: If the yaw angle signal ya is negative, the spiral drive wheels on both sides are controlled to rotate clockwise at the same time; If the yaw angle signal ya is positive, the spiral drive wheels on both sides are controlled to rotate counterclockwise at the same time; The expression is: w1 is the speed of the spiral driving wheel close to the negative direction of the X-axis, w2 is the speed of the right spiral wheel close to the positive direction of the X-axis, w0 is the initial speed of the spiral driving wheel, and the spiral blades on the spiral driving wheels on both sides have opposite spiral directions.

7. A flexible seedling avoidance and seedling row tracking control method according to claim 3, characterized in that: The step of achieving the spiral driving wheel to rotate in situ around the rotation center in S4 includes: An incremental PI speed controller is provided for adjusting the rotation speed of the screw drive wheel; The real-time rotation speed of the helical driving wheel is obtained, and based on the incremental PI speed controller, the real-time rotation speed and the rotation speed difference Δw are used to calculate the torque current signal for controlling the helical driving wheel.

8. A flexible seedling avoidance and seedling row tracking control method according to claim 3, characterized in that: The S5 includes: If the preview heading angle δ is equal to 0, the spiral drive wheel is controlled to maintain the original speed; If the pre-aiming heading angle δ is greater than 0, the speed of the spiral driving wheel is changed to make the miniature rice field weeder deflect toward the negative direction of the X axis. If the pre-aiming heading angle δ is less than 0, the speed of the spiral driving wheel is changed to make the miniature rice field weeder deflect toward the positive direction of the X axis. The expression is: Wherein, w1 is the speed of the spiral driving wheel close to the negative direction of the X-axis, w2 is the speed of the right spiral wheel close to the positive direction of the X-axis, w0 is the initial speed of the spiral driving wheel, Δw is the speed difference between the two spiral driving wheels, and the spiral blades on the spiral driving wheels on both sides have opposite spiral directions.

9. A flexible seedling avoidance and seedling row tracking control method according to claim 3, characterized in that: The step of calculating the speed difference between the two spiral drive wheels according to the differential principle in S5 includes: A fuzzy controller is constructed with the preview heading angle δ as input and the rotation speed difference Δω between the two spiral drive wheels as output; The fuzzy controller calculates the rotation speed difference Δw according to the corresponding relationship between the preview heading angle δ and the quantization level of the rotation speed difference Δw.

10. A flexible seedling avoidance and seedling row tracking control system according to any one of claims 3-9, characterized in that: include: Flexible bending sensor voltage signal processing unit, attitude sensor yaw angle signal processing unit, wherein, The flexible curvature sensor voltage signal processing unit is used to obtain in real time the voltage signals v1 and v2 of the flexible curvature sensors on both sides of the miniature rice field weeder during the movement between the seedling rows, and solve the lateral distances x1 and x2 from the centroid of the miniature rice field weeder to the collision positions on both sides according to the preset fitting curve equation, and then output the lateral deviation d between the centroid of the miniature rice field weeder and the center line between the rows of seedlings on both sides; convert the lateral deviation into an angle deviation, that is, the angle deviation δ between the line connecting the centroid of the miniature rice field weeder to the collision position on the deviation side and the Y-axis, and the angle deviation δ is the pre-aiming heading angle; The attitude sensor yaw angle signal processing unit is used to obtain the yaw angle signal of the attitude sensor of the mini rice field weeder in real time during the movement between seedling rows, and judge whether the yaw angle signal is less than the absolute value range β of the pre-aiming heading angle δ; if not, output the control of the two spiral drive wheels rotating in the same direction, so as to make the spiral drive wheels rotate in place around the rotation center until the yaw angle signal is less than the absolute value range β; if so, based on the size relationship between the pre-aiming heading angle δ and 0°, output the control instruction of the two spiral drive wheels rotating in the opposite direction, and calculate the speed difference of the two spiral drive wheels according to the differential principle, so as to adjust the speed of the spiral drive wheels until the mini rice field weeder moves along the center line between the seedling rows on both sides.

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