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

Abstract

The application provides a miniature rice field weeding machine and a flexible seedling avoidance and seedling row tracking control method and system, relates to the field of mechanical weeding in rice fields, and comprises a spiral driving type miniature weeding machine, a flexible bending degree sensor, a posture sensor and a steering control unit. The flexible bending degree sensor is used for detecting the position of seedlings and outputting an analog voltage signal through collision to calculate the lateral distance; the posture sensor measures the yaw angle of the weeding machine in real time; and the steering control unit adjusts the rotating speed of the driving motors on both sides based on a fuzzy controller to realize differential steering or in-place steering. The application has the advantages of low cost, high reliability and strong environmental adaptability, can stably work in a complex rice field environment, and provides a new solution for the mechanization of rice planting.

Description

Technical Field

[0001] This invention belongs to the field of agricultural machinery technology, and relates to a miniature paddy field weeder and a flexible seedling avoidance and seedling row tracking control method and system. Background Technology

[0002] Weeds in paddy fields are a significant factor affecting the normal growth of rice seedlings, directly impacting rice yield and quality. Compared to manual and chemical weeding, mechanical weeding offers advantages such as reducing environmental pollution, lowering production costs, and increasing labor efficiency.

[0003] Compared to large-scale mechanical weeding equipment, mini weeders have advantages such as small size, flexible movement, and low seedling damage rate. Their spiral-driven locomotion not only overcomes the difficulties of traditional wheeled and tracked machinery, such as getting stuck or slipping, but also continuously agitates the paddy field soil and water, effectively increasing water turbidity and inhibiting weed photosynthesis. Due to the agronomical characteristics of rice cultivation, weeders need to ensure stable operation between rows to avoid crushing seedlings on either side.

[0004] However, traditional mini weeders typically lack effective seedling avoidance capabilities, easily crushing seedlings and causing crop damage. Furthermore, traditional weeders rely heavily on image processing or positioning navigation technology for path planning, but these methods are easily affected by interference in wet, muddy paddy field environments, leading to decreased accuracy and making it difficult to implement existing automatic seedling tracking control technology in complex paddy field conditions. Moreover, control systems based on image processing or high-precision positioning navigation require expensive hardware and complex computing resources, ultimately increasing equipment costs.

[0005] A seedling avoidance and seedling row tracking technology needs to be proposed to control the weeder so that it can move automatically between rows.

[0006] Therefore, how to provide a micro paddy field weeder that can simultaneously achieve high stability and low cost, as well as a flexible seedling avoidance and seedling row tracking control method and system, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention proposes a miniature paddy field weeder and a flexible seedling avoidance and seedling row tracking control method and system. Through low-cost and high-reliability design, the miniature weeder achieves flexible seedling avoidance and seedling row tracking functions.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention discloses a miniature rice paddy weeding machine, comprising: a weeding machine frame, a spiral drive wheel, a flexible bending sensor, a posture sensor, and a steering control unit; wherein,

[0010] The spiral drive wheel has two wheels, which are located on both sides of the bottom of the weeder frame, and the spiral drive wheel has spiral blades.

[0011] The flexible bending sensor has two components, which are horizontally arranged at the front end of the weeder frame. They are used to output voltage signals after touching the seedling rows on both sides to generate bending deformation. The two flexible bending sensors are of the same length.

[0012] The attitude sensor is installed at the center of mass of the miniature rice paddy weeder 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 yaw angle signal in real time, and control the steering and / or speed of the spiral drive wheel according to the flexible seedling avoidance and seedling tracking strategy, so as to correct the target path deviation of the weeder in real time.

[0014] Preferably, the spiral drive wheel is a hollow spiral drive wheel, and the spiral blades on the two spiral drive wheels have opposite spiral directions.

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

[0016] This invention also discloses a flexible seedling avoidance and seedling row tracking control method based on the aforementioned miniature paddy field weeder, comprising the following steps:

[0017] S1: Real-time acquisition of voltage signals v1 and v2 from flexible bending degree sensors on both sides during the movement of the mini rice paddy weeder between rows, and calculation of the lateral distances x1 and x2 from the centroid of the mini rice paddy weeder to the collision positions on both sides according to the preset fitting curve equation, and then outputting the lateral deviation d between the centroid of the mini rice paddy weeder and the center line between the rows of seedlings on both sides.

[0018] S2: Convert the lateral deviation into angular deviation, that is, the angular deviation δ between the line connecting the center of mass of the mini paddy field weeder to the collision position on the deviation side and the Y-axis, and the angular deviation δ is the pre-aiming heading angle;

[0019] S3: Real-time acquisition of the yaw angle signal of the attitude sensor during the movement of the mini rice paddy weeder between the rows of seedlings, and determination of whether the yaw angle signal is less than the absolute value range of the pre-aiming heading angle δ is β; if not, proceed to S4, if yes, proceed to S5;

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

[0021] S5: Based on the relationship between the pre-aiming heading angle δ and 0°, control the two spiral drive wheels to rotate in opposite directions, and calculate the speed difference between the two spiral drive wheels according to the differential speed principle to adjust the speed of the spiral drive wheels until the micro paddy field weeder moves along the center line between the rows of rice seedlings on both sides.

[0022] Preferably, the preset fitting curve equation in S1 is a curve equation obtained by fitting the output voltage signal v of the flexible bending degree sensor based on historical data and the lateral distance x from the center of mass of the miniature paddy field weeder to the collision positions on both sides; the lateral deviation

[0023] Preferably, in step S3, the calculation step of the absolute value range β of the pre-aiming heading angle δ includes:

[0024] S31: Using the length value of the curvature sensor, calibrate the maximum value of the lateral distances x1 and x2;

[0025] S32: with The extreme values ​​of the angular deviation δ are calculated, taking the lateral deviation d between the centroid of the miniature rice paddy weeder and the center line between the rows of rice seedlings on both sides as the reference point:

[0026]

[0027] In the formula, l is the longitudinal distance from the intersection of the seedling centerline and the flexible curvature sensor along the X-axis to the centroid of the micro paddy field weeder.

[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, then control both sides of the propeller drive wheel to rotate clockwise simultaneously;

[0031] If the yaw angle signal ya is positive, then control both sides of the propeller drive wheel to rotate counterclockwise simultaneously;

[0032] The expression is:

[0033]

[0034] w1 is the rotational speed of the helical drive wheel closest to the negative X-axis, w2 is the rotational speed of the right helical wheel closest to the positive X-axis, and w0 is the initial rotational speed of the helical drive wheel. The helical blades on the two helical drive wheels have opposite helical directions.

[0035] Preferably, the step in S4 that enables the helical drive wheel to rotate in place around the rotation center includes:

[0036] An incremental PI speed controller is installed to adjust the rotational speed of the helical drive wheel;

[0037] The real-time rotational speed of the helical drive wheel is obtained, and based on the incremental PI speed controller, the torque current signal for controlling the helical drive wheel is calculated using the real-time rotational speed and the speed difference Δw.

[0038] Preferably, S5 includes:

[0039] If the pre-aiming heading angle δ is equal to 0, then control the spiral drive wheel to maintain its original speed;

[0040] If the pre-aiming heading angle δ is greater than 0, the rotational speed of the helical drive wheel is changed to make the miniature paddy field weeder deflect in the negative X-axis direction; if the pre-aiming heading angle δ is less than 0, the rotational speed of the helical drive wheel is changed to make the miniature paddy field weeder deflect in the positive X-axis direction. The expression is:

[0041]

[0042] In the formula, w1 is the rotational speed of the helical drive wheel closest to the negative X-axis, w2 is the rotational speed of the right helical wheel closest to the positive X-axis, w0 is the initial rotational speed of the helical drive wheel, Δw is the rotational speed difference between the two helical drive wheels, and the helical blades on the two helical drive wheels have opposite helical directions.

[0043] Preferably, the step in S5 of calculating the speed difference between the two helical drive wheels based on the differential principle includes:

[0044] A fuzzy controller is constructed using the pre-aiming heading angle δ as the input and the speed difference Δω between the two helical drive wheels as the output.

[0045] The fuzzy controller calculates the speed difference Δw based on the quantization level correspondence between the pre-aiming heading angle δ and the speed difference Δw.

[0046] This invention also discloses a flexible seedling avoidance and seedling tracking control system based on the aforementioned flexible seedling avoidance and seedling tracking control method, comprising: a flexible curvature sensor voltage signal processing unit, an attitude sensor yaw angle signal processing unit, wherein,

[0047] The flexible bending degree sensor voltage signal processing unit is used to acquire the voltage signals v1 and v2 of the flexible bending degree sensors on both sides of the micro paddy field weeder in real time during the movement between the rows of seedlings, and calculate the lateral distances x1 and x2 from the center of mass of the micro paddy 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 center of mass of the micro paddy field weeder and the center line between the rows of seedlings on both sides; convert the lateral deviation into an angular deviation, that is, the angular deviation δ between the line connecting the center of mass of the micro paddy field weeder to the collision position on the deviation side and the Y-axis, and the angular deviation δ is the pre-aiming heading angle;

[0048] The attitude sensor yaw angle signal processing unit is used to acquire the yaw angle signal of the attitude sensor in real time during the movement of the miniature rice paddy weeder between the rows of seedlings, and to determine whether the yaw angle signal is less than the absolute value range β of the pre-aiming heading angle δ; if not, it outputs control to rotate the two spiral drive wheels in the same direction, so that 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 relationship between the pre-aiming heading angle δ and 0°, it outputs control commands to rotate the two spiral drive wheels in opposite directions, and calculates the speed difference between the two spiral drive wheels according to the differential speed principle, so as to adjust the speed of the spiral drive wheels until the miniature rice paddy weeder moves along the center line between the rows of seedlings on both sides.

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

[0050] This invention achieves flexible seedling avoidance and automatic seedling tracking functions for a miniature weeder by introducing a flexible bending degree sensor and an attitude sensor, combined with a fuzzy controller and a differential steering strategy.

[0051] The method proposed in this invention mainly uses a flexible bending degree sensor to directly sense the position of seedlings, avoiding reliance on complex visual algorithms. The system is insensitive to factors such as ambient light and soil moisture, and compared to image processing and positioning navigation, it has lower costs and stronger environmental adaptability.

[0052] This invention achieves intelligent path planning and real-time adjustment through a fuzzy controller and an incremental PI speed controller. Users only need to drive the weeder to the target starting point, and it will automatically complete seedling tracking and avoidance operations, enabling the weeder to operate stably in the complex terrain of paddy fields and significantly improving work efficiency. The helical drive wheels used have superior driving performance compared to traditional tracked and wheeled drive wheels. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0054] Figure 1 The diagram shows the effect of the miniature weeder's flexible seedling avoidance and seedling row tracking provided in the embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram illustrating the principle of flexible seedling avoidance and seedling row tracking of a miniature weeder provided in an embodiment of the present invention.

[0056] Figure 3 This is a flowchart of a method for flexible seedling avoidance and seedling row tracking control of a miniature weeder provided in an embodiment of the present invention;

[0057] Figure 4 This is a schematic diagram of the flexible seedling avoidance and seedling row tracking control structure of the miniature weeder provided in an embodiment of the present invention;

[0058] In the picture:

[0059] 1 represents rice seedlings; 2 represents the weeder frame; 3 represents the helical drive wheel; 4 represents the flexible bending sensor; 5 represents the control box; point O represents the center of gravity of the miniature rice paddy weeder; ICR represents the actual differential steering rotation center of the miniature rice paddy weeder; B represents the center distance between the left and right helical wheels of the miniature rice paddy weeder; R represents the actual differential rotation radius of the miniature rice paddy weeder; Vc represents the longitudinal forward speed at the center of gravity of the miniature rice paddy weeder; V l V r δ represents the actual speed of the left and right spiral drive wheels considering slip rate; Q represents the center line of the rice seedlings on both sides; d represents the lateral distance between the center line of the row and the center of mass of the mini rice paddy weeder; x1 and x2 represent the lateral distance between the real-time acquisition device position of the left and right bending sensors and the center of mass of the mini rice paddy weeder, respectively; δ represents the pre-aiming heading angle; l represents the longitudinal distance from the bending sensor to the center of mass of the mini rice paddy weeder; and θ represents the turning angle of the mini rice paddy weeder. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] The first aspect of this invention provides a miniature rice paddy weeder, comprising: a weeder frame 2, a spiral drive wheel 3, a flexible bending sensor 4, an attitude sensor, and a steering control unit; wherein,

[0062] Two spiral drive wheels 3 are located on both sides of the bottom of the weeder frame 2, and each spiral drive wheel 3 has spiral blades. Two flexible bending degree sensors 4 are located laterally at the front end of the weeder frame 2. They are used to output voltage signals after the seedling rows 1 on both sides are bent and deformed. The two flexible bending degree sensors 4 are of the same length. An attitude sensor is installed at the center of mass of the micro paddy field weeder to measure and output yaw angle signals in real time. The steering control unit is used to receive voltage signals and yaw angle signals in real time, and to control the steering and / or speed of the spiral drive wheels 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.

[0063] like Figure 1 As shown, a miniature rice paddy weeder travels between two rows of rice seedlings 1. A flexible bending sensor 4 extends horizontally to both sides of the weeder, its function being to sense whether the weeder comes into contact with the seedlings during its movement and to estimate the lateral distance between the seedlings and the weeder's center of gravity. The core principle of the flexible bending sensor is based on the change in resistance or capacitance within the material caused by physical deformation. For a resistance-changing flexible bending sensor, when the sensor bends, its internal resistance changes with the bending angle. The larger the bending angle, the more significant the resistance change, and the sensor converts this resistance change into an analog voltage signal output. When the weeder moves, the flexible bending sensor may slightly collide with the seedlings. This collision causes the sensor to bend, and its internal resistance or capacitance changes accordingly.

[0064] In one embodiment, the spiral drive wheel is a hollow spiral drive wheel, and the spiral blades on both sides of the spiral drive wheel spiral in opposite directions. During the movement of the mini weeder, the spiral drive component turns and mixes the soil, which not only destroys the root system of weeds, increases the turbidity of the paddy field water layer, and inhibits the photosynthesis of weeds, but also improves the stability and passability of the weeder's self-propelled movement, and avoids crushing the seedlings.

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

[0066] In one embodiment, such as Figure 1As shown, a control box is installed on the frame of the weeder for mounting the steering control unit. The steering control unit mainly includes a main controller, a brushless DC drive motor with a built-in speed sensor, and a brushless motor speed controller. The main controller receives voltage and yaw angle signals in real time and sends commands to the brushless motor speed controller to control the steering and / or speed of the brushless DC drive motor according to the flexible seedling avoidance and seedling tracking strategy, thereby correcting the target path deviation of the weeder in real time.

[0067] The second aspect of this invention also discloses a flexible seedling avoidance and seedling row tracking control method for a miniature paddy field weeder according to the first aspect of the invention, such as... Figure 2 The parameters shown in the document include the following steps:

[0068] S1: Set the target rotation speed w0 of the two spiral drive wheels, initialize the sensor data, start the automatic seedling row tracking operation of the weeder, acquire the voltage signals v1 and v2 of the flexible bending degree sensors on both sides during the movement of the mini rice field weeder between the seedling rows in real time, and calculate the lateral distances x1 and x2 from the centroid of the mini 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 mini rice field weeder and the center line between the seedling rows on both sides.

[0069] S2: Convert the lateral deviation into angular deviation, that is, the angular deviation δ between the line connecting the center of mass of the mini paddy field weeder to the collision position on the deviation side and the Y-axis. The angular deviation δ is the pre-aiming heading angle.

[0070] S3: Real-time acquisition of the yaw angle signal from the attitude sensor during the movement of the mini rice paddy weeder between rows, and determination of whether the yaw angle signal is less than the absolute value range of the pre-aiming heading angle δ (β); if not, proceed to S4, if yes, proceed to S5;

[0071] S4: Control the two helical drive wheels to rotate in the same direction, so that the helical drive wheels can rotate in place around the rotation center until the yaw angle signal is less than the absolute value range β, then enter S5;

[0072] 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 speed principle to realize the speed adjustment of the spiral drive wheels until the miniature paddy field weeder moves along the center line between the rows of rice seedlings on both sides.

[0073] It should be noted that the implementation of flexible seedling avoidance and seedling row tracking of the weeder mainly includes two parts: calculating the pre-aiming heading angle by measuring the analog voltage signal of the flexible curvature sensor and processing and analyzing the data of the yaw angle output by the attitude sensor to output the target speed of the propeller wheel and the speed of the drive motor of the steering control unit. When the flexible curvature sensor collides with the seedlings and the weeder deflects at a large angle during inter-row operation, the target speed for the next moment is sent to the steering control unit to correct the deviation of the target path of the weeder in real time and avoid crushing the seedlings.

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

[0075] In practice, a target stable driving speed is set, and multiple collision tests are conducted at different positions of the curvature sensor during the movement of the weeding robot. The equation of the curve between the output voltage signal of the curvature sensor and the lateral distance is calibrated and fitted, for example, x = a*v + b.

[0076] In this embodiment, lateral deviation

[0077] In one embodiment, in S1, the signals of the flexible bending degree sensors on the left and right sides are periodically (10ms) read, and after median value filtering, the lowest analog voltage values ​​v1 and v2 at the moment of separation during the collision between the sensor and the seedling are obtained.

[0078] In one embodiment, in S3, the attitude sensor signal at the center of mass of the micro weed cutter is read, and the weed cutter's yaw angle ya is obtained after low-pass filtering; the internal speed sensor signal of the brushless DC drive motor is read, and the rotor speed information is obtained through the CAN bus and processed to obtain the speeds w1′ and w2′ of the two helical wheels.

[0079] In one embodiment, when the mini weeder deflects, one side of the sensor may collide with the seedling while the other side does not. When the flexible bending sensor at the point of impact experiences maximum bending, the lateral distance d reaches its maximum value, and the corresponding pre-aiming 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 pre-aiming heading angle δ include:

[0080] S31: Using the length value of the curvature sensor, calibrate the maximum value of the lateral distances x1 and x2;

[0081] S32: with The extreme values ​​of the angular deviation δ are calculated, taking the lateral deviation d between the centroid of the miniature rice paddy weeder and the center line between the rows of rice seedlings on both sides as the reference point:

[0082]

[0083] In the formula, l is the longitudinal distance from the intersection of the seedling centerline and the X-axis where the flexible bending sensor is located to the centroid of the micro paddy field weeder; in the 3D modeling software, the density and weight of each part of the weeder are assigned, and the coordinates of the centroid can be obtained in the mass attribute, thereby measuring 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 miniature paddy field weeder shifts between two rows of seedlings until the end of the flexible curvature sensor on one side just contacts the corresponding row and outputs a voltage signal, further shifting to that side will result in no voltage signal output. This state is used as the limit state for calculating the extreme value of the angular deviation δ, thereby obtaining the calculated value of the lateral distance x on that side as 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 of the aiming heading angle δ, geometric relationships are also relied upon. The calculation yields the current driving status of the weeder between the seedling rows, which can be derived from the value of δ.

[0087] When |ya|≤|β|, it means that the flexible bending sensors on both sides of the weeder hit the seedlings, and the spiral drive wheels on both sides of the weeder adjust the direction according to the differential speed principle, entering S5; when |ya|>|β|, it means that the weeder is affected by the unstable factors of the paddy field ground and deflects at a large angle, controlling the spiral drive wheels on both sides to rotate in the same direction, realizing the turning in place, entering S4.

[0088] In one embodiment, given the complex conditions of paddy field surfaces, the weeder's travel direction may experience significant deflection, resulting in |ya| > |β|. In this case, S4 includes:

[0089] If the yaw angle signal ya is negative, then control both sides of the propeller drive wheel to rotate clockwise simultaneously;

[0090] If the yaw angle signal ya is positive, then control both sides of the propeller drive wheel to rotate counterclockwise simultaneously;

[0091] The expression is:

[0092]

[0093] w1 is the rotational speed of the helical drive wheel closest to the negative X-axis, w2 is the rotational speed of the right helical wheel closest to the positive X-axis, and w0 is the initial rotational speed of the helical drive wheel. The helical blades on the two helical drive wheels have opposite helical directions.

[0094] like Figure 3As shown, under wet and soft ground conditions, the axial forces generated by the simultaneous rotation of the two helical wheels are in opposite directions and act on the axis of the helical wheels, making the resultant force on the weed cutter a steering torque, thus causing it to rotate around the center of rotation. When ya is negative, the weed cutter produces a large rightward deflection, and both helical wheels rotate clockwise simultaneously, allowing the weed cutter to rotate counterclockwise in place until δ > -δ. m When ya is positive, the weed cutter experiences a large leftward deflection, and both augers rotate counterclockwise simultaneously, causing the weed cutter to rotate clockwise in place until δ < δ m .

[0095] In one embodiment, step S4, which enables the helical drive wheel to rotate in place around the rotation center, includes:

[0096] An incremental PI speed controller is installed to adjust the rotational speed of the helical drive wheel;

[0097] The real-time rotational speed of the helical drive wheel is obtained. Based on an incremental PI speed controller, the torque current signal controlling the helical drive wheel is calculated using the real-time rotational speed and the speed difference Δw.

[0098] In specific implementation, such as Figure 4 As shown, the spiral drive wheel encounters significant resistance when rotating forward on the surface of paddy field silt. Therefore, to ensure that the rotational speed of both spiral wheels remains stable near the target speed, an incremental PI speed controller is used to adjust the motor speed. The real-time rotor speed is obtained using the speed sensor built into the brushless DC drive motor, and the output shaft speed is calculated by dividing by the reduction ratio. The torque current signal for controlling the motor speed is calculated based on the deviation between the actual feedback speed and the target speed. In this design, the PI speed controller takes the difference between the output shaft speed fed back from the ESC CAN bus message and the target spiral wheel speed as input, and uses the sum of the proportional and integral parts accumulated by the controller in real time as the torque current value output. The speed sampling period is set to 10 milliseconds. In each sampling period, the speed deviation is first calculated and the integral part value is updated. The difference between the current deviation and the previous deviation is used as the proportional part input. The sum of the integral and proportional parts is used as the incremental PI controller current value output, and the output current value is limited to prevent excessive current from burning out the motor. Finally, the deviation storage is updated, and the current deviation value is used as the previous deviation for 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 indicates that the bending sensors on both sides of the weeder have not collided with any seedlings, or the current centroid of the weeder is on the center line of the seedling row, and the screw driving wheels are controlled to keep running at the original speed; if δ is greater than or less than 0, it indicates that the weeder is deviated from the center line of the seedling row at this moment, and the rotation speeds of the screw wheels on both sides need to be changed according to the value of δ, specifically:

[0101] If the preview heading angle δ is greater than 0, changing the rotation speed of the screw driving wheels to make the miniature paddy field weeder deflect towards the negative direction of the X-axis; if the preview heading angle δ is less than 0, changing the rotation speed of the screw driving wheels to make the miniature paddy field weeder deflect towards the positive direction of the X-axis, and the expression is:

[0102]

[0103] In the formula, w1 is the rotation speed of the screw driving wheel close to the negative direction of the X-axis, w2 is the rotation speed of the right screw wheel close to the positive direction of the X-axis, w0 is the initial rotation speed of the screw driving wheels, Δw is the rotation speed difference between the two screw driving wheels, and the spiral directions of the spiral blades on the screw driving wheels on both sides are opposite.

[0104] In specific implementation, as shown in Figure 2 , when δ < 0, x2 < x1, the bending sensor on the right side of the weeder collides with a seedling, that is, the traveling direction deflects to the right, therefore, the rotation speed of the right screw driving wheel should be appropriately increased, and the rotation speed of the screw wheel on the other side remains unchanged, so as to increase the propelling force on the right side and urge the weeder to adjust its heading to the left. Meanwhile, the absolute value of the output rotation speed difference increases as the absolute value of the preview heading angle δ increases; when δ > 0, x2 > x1, the bending sensor on the left side of the weeder collides with a seedling, that is, the traveling direction deflects to the left, therefore, the rotation speed of the left screw driving wheel should be appropriately increased, and the rotation speed of the screw wheel on the other side remains unchanged, so as to increase the propelling force on the left side and urge the weeder to adjust its heading to the right; meanwhile, the absolute value of the output rotation speed difference increases as the absolute value of the preview heading angle δ increases.

[0105] In one embodiment, in step S5, the step of calculating the rotation speed difference between two screw driving wheels according to the differential speed principle comprises:

[0106] constructing a fuzzy controller by taking the preview heading angle δ as the input and the rotation speed difference Δω of the two screw driving wheels as the output;

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

[0108] In this embodiment, the quantization level of the pre-aiming heading angle δ is divided into 7 levels, with negative large, negative medium, negative small, zero, positive small, positive medium, and positive large represented by NB, NM, NS, Z, PS, PM, and PB, respectively; the basic domain of discourse of the speed difference Δw is set to [-210rpm, 210rpm], and the quantization level of the speed difference is divided into 7 levels, with negative large, negative medium, negative small, zero, positive small, positive medium, and positive large represented by NB, NM, NS, Z, PS, PM, and PB, respectively.

[0109] This invention also discloses a flexible seedling avoidance and seedling tracking control system based on a flexible seedling avoidance and seedling tracking control method, comprising: a flexible curvature sensor voltage signal processing unit, an attitude sensor yaw angle signal processing unit, wherein,

[0110] The flexible bending degree sensor voltage signal processing unit is used to acquire the voltage signals v1 and v2 of the flexible bending degree sensors on both sides of the micro paddy field weeder in real time during the movement between the rows of seedlings. It calculates the lateral distances x1 and x2 from the center of mass of the micro paddy field weeder to the collision positions on both sides according to the preset fitting curve equation, and then outputs the lateral deviation d between the center of mass of the micro paddy field weeder and the center line between the rows of seedlings on both sides. The lateral deviation is converted into angular deviation, that is, the angular deviation δ between the line connecting the center of mass of the micro paddy field weeder to the collision position on the deviation side and the Y-axis. The angular deviation δ is the pre-aiming heading angle.

[0111] The attitude sensor yaw angle signal processing unit is used to acquire the yaw angle signal of the attitude sensor in real time during the movement of the mini rice paddy weeder between the rows of seedlings. It determines whether the yaw angle signal is less than the absolute value range of the pre-aiming heading angle δ (β). If not, it outputs control for the two helical drive wheels to rotate in the same direction, so that the helical 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 relationship between the pre-aiming heading angle δ and 0°, it outputs control commands for the two helical drive wheels to rotate in opposite directions, and calculates the speed difference between the two helical drive wheels according to the differential speed principle, so as to adjust the speed of the helical drive wheels until the mini rice paddy weeder moves along the center line between the rows of seedlings on both sides.

[0112] The above provides a detailed description of the miniature paddy field weeder and the flexible seedling avoidance and seedling row tracking control method and system provided by the present invention. Specific examples are used in this embodiment to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

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

Claims

1. A flexible seedling avoidance and seedling row tracking control method for a miniature paddy field weeder, characterized in that, The miniature rice paddy weeder includes: a weeder frame, a spiral drive wheel, a flexible bending sensor, a posture sensor, and a steering control unit; wherein... The spiral drive wheel has two wheels, which are located on both sides of the bottom of the weeder frame, and the spiral drive wheel has spiral blades. The flexible bending sensor has two components, which are horizontally arranged at the front end of the weeder frame. They are used to output voltage signals after touching the seedling rows on both sides to generate bending deformation. The two flexible bending sensors are of the same length. The attitude sensor is installed at the center of mass of the miniature rice paddy weeder and is used to measure and output the yaw angle signal in real time. The steering control unit is used to receive the voltage signal and yaw angle signal in real time, and control the steering and / or speed of the spiral drive wheel according to the flexible seedling avoidance and seedling tracking strategy, so as to correct the target path deviation of the weeder in real time. The flexible seedling avoidance and seedling row tracking control method includes the following steps: S1: Real-time acquisition of voltage signals v1 and v2 from flexible bending degree sensors on both sides during the movement of the mini rice paddy weeder between rows, and calculation of the lateral distances x1 and x2 from the centroid of the mini rice paddy weeder to the collision positions on both sides according to the preset fitting curve equation, and then outputting the lateral deviation d between the centroid of the mini rice paddy weeder and the center line between the rows of seedlings on both sides. S2: Convert the lateral deviation into angular deviation, that is, the angular deviation δ between the line connecting the center of mass of the mini paddy field weeder to the collision position on the deviation side and the Y-axis, and the angular deviation δ is the pre-aiming heading angle; S3: Real-time acquisition of the yaw angle signal of the attitude sensor during the movement of the mini rice paddy weeder between the rows of seedlings, and determination of whether the yaw angle signal is less than the absolute value range β of the pre-aiming heading angle δ; if not, proceed to S4, if yes, proceed to S5; S4: Control the two spiral drive wheels to rotate in the same direction, so that the spiral drive wheels can rotate in place around the rotation center until the yaw angle signal is less than the absolute value range β, then proceed to S5; S5: Based on the relationship between the pre-aiming heading angle δ and 0°, control the two spiral drive wheels to rotate in opposite directions, and calculate the speed difference between the two spiral drive wheels according to the differential speed principle to realize the speed adjustment of the spiral drive wheels until the micro paddy field weeder moves along the center line between the rows of rice seedlings on both sides; The calculation steps for the absolute value range β of the pre-aiming heading angle δ include: S31: Using the length value of the curvature sensor, calibrate the maximum value x of the lateral distances x1 and x2. max ; S32: with The extreme values ​​of the angular deviation δ are calculated, taking the lateral deviation d between the centroid of the miniature rice paddy weeder and the center line between the rows of rice seedlings on both sides as the reference point: ； In the formula, l is the longitudinal distance from the intersection of the seedling centerline and the X-axis where the flexible curvature sensor is located to the centroid of the micro paddy field weeder. S33: Determine the absolute value range β as [ ].

2. The flexible seedling avoidance and seedling row tracking control method according to claim 1, characterized in that, One end of the flexible bending degree sensor is fixed at the same height position at the front end of the weeder frame, and the other end extends outward along the X-axis towards the outer side of the weeder frame. The X-axis is perpendicular to the forward direction Y-axis of the micro paddy field weeder, and the two flexible bending degree sensors are respectively set to extend along the positive and negative X-axis.

3. The flexible seedling avoidance and seedling row tracking control method according to claim 1, characterized in that, The preset fitting curve equation in S1 is the curve equation obtained by fitting the output voltage signal v of the flexible bending degree sensor based on historical data and the lateral distance x from the center of mass of the miniature paddy field weeder to the collision positions on both sides; the lateral deviation .

4. The flexible seedling avoidance and seedling row tracking control method according to claim 1, characterized in that, S4 includes: If the yaw angle signal ya is negative, then control both sides of the propeller drive wheel to rotate clockwise simultaneously; If the yaw angle signal ya is positive, then control both sides of the propeller drive wheel to rotate counterclockwise simultaneously; The expression is: ； The rotational speed of the left helical drive wheel, which is closer to the negative X-axis. The rotational speed of the right-side helical drive wheel, which is closer to the positive X-axis. The initial rotational speed of the helical drive wheel is given, and the helical blades on both sides of the helical drive wheel rotate in opposite directions.

5. The flexible seedling avoidance and seedling row tracking control method according to claim 1, characterized in that, The step in S4 to achieve the rotational motion of the helical drive wheel around the rotation center includes: An incremental PI speed controller is installed to adjust the rotational speed of the helical drive wheel; The real-time rotational speed of the helical drive wheel is obtained, and based on the incremental PI speed controller, the torque current signal for controlling the helical drive wheel is calculated using the real-time rotational speed and the speed difference Δw.

6. The flexible seedling avoidance and seedling row tracking control method according to claim 1, characterized in that, S5 includes: If the pre-aiming heading angle δ is equal to 0, then control the spiral drive wheel to maintain its original speed; If the pre-aiming heading angle δ is greater than 0, the rotational speed of the helical drive wheel is changed to make the miniature paddy field weeder deflect in the negative X-axis direction; if the pre-aiming heading angle δ is less than 0, the rotational speed of the helical drive wheel is changed to make the miniature paddy field weeder deflect in the positive X-axis direction. The expression is: ； In the formula, The rotational speed of the left helical drive wheel, which is closer to the negative X-axis. The rotational speed of the right-side helical drive wheel, which is closer to the positive X-axis. The initial rotational speed of the helical drive wheel is given. The difference in rotational speed between the two spiral drive wheels is represented by the difference in the spiral direction of the spiral blades on both sides of the spiral drive wheels.

7. The flexible seedling avoidance and seedling row tracking control method according to claim 1, characterized in that, The step in S5 of calculating the speed difference between the two helical drive wheels based on the differential speed principle includes: A fuzzy controller is constructed using the pre-aiming heading angle δ as the input and the speed difference Δw between the two helical drive wheels as the output. The fuzzy controller calculates the speed difference Δw based on the quantization level correspondence between the pre-aiming heading angle δ and the speed difference Δw.

8. A flexible seedling avoidance and seedling row tracking control system according to any one of claims 1-7, characterized in that, include: The flexible curvature sensor voltage signal processing unit and the attitude sensor yaw angle signal processing unit, among which, The flexible bending degree sensor voltage signal processing unit is used to acquire the voltage signals v1 and v2 of the flexible bending degree sensors on both sides of the micro paddy field weeder in real time during the movement between the rows of seedlings, and calculate the lateral distances x1 and x2 from the center of mass of the micro paddy 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 center of mass of the micro paddy field weeder and the center line between the rows of seedlings on both sides; convert the lateral deviation into an angular deviation, that is, the angular deviation δ between the line connecting the center of mass of the micro paddy field weeder to the collision position on the deviation side and the Y-axis, and the angular deviation δ is the pre-aiming heading angle; The attitude sensor yaw angle signal processing unit is used to acquire the yaw angle signal of the attitude sensor in real time during the movement of the miniature rice paddy weeder between the rows of seedlings, and to determine whether the yaw angle signal is less than the absolute value range β of the pre-aiming heading angle δ; if not, it outputs control to rotate the two spiral drive wheels in the same direction, so that 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 relationship between the pre-aiming heading angle δ and 0°, it outputs control commands to rotate the two spiral drive wheels in opposite directions, and calculates the speed difference between the two spiral drive wheels according to the differential speed principle, so as to adjust the speed of the spiral drive wheels until the miniature rice paddy weeder moves along the center line between the rows of seedlings on both sides.

Images