Electrically based three-point linkage tillage implement levelling and depth adjustment device and method

Abstract

The application discloses a three-point suspension rotary tiller leveling and depth adjusting device and method based on electricity. The leveling and depth adjusting device comprises leveling electric cylinders, an upper pull rod, an upper swing arm, a lifting electric cylinder and a lower pull rod. The pitch angle and the lateral tilt angle of the rotary tiller are monitored by a double-axis tilt sensor. Two leveling electric cylinders are first triggered to act according to the lateral tilt angle, and the two leveling electric cylinders are differentially adjusted to compensate the extension amount so as to restore the lateral tilt angle of the rotary tiller to 0. Then, a depth automatic control strategy based on the rotary tiller motor current and the rotary tiller posture is constructed. The pitch angle of the rotary tiller is monitored in real time by the double-axis tilt sensor, and the lifting electric cylinder is dynamically adjusted in combination with the rotary tiller motor current real-time data to compensate the pitch angle. The application solves the problems of slow response, low precision and dependence on force sensors to estimate load in the traditional hydraulic system, which is easy to be disturbed by machine body vibration and soil resistance mutation. The application reduces the influence of soil resistance and machine posture on the depth, and improves the operation quality.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, specifically to an automatic leveling and tillage depth adjustment device and method for an electric three-point suspension rotary tiller, applicable to precise tillage depth control of implements such as electric tracked rotary tillers. Background Technology

[0002] Traditional hydraulic suspension systems suffer from sluggish response, large deviations in tillage depth, reliance on force sensors for indirect load estimation, and susceptibility to machine vibration and sudden changes in soil resistance. Existing tillage depth control systems often employ a single force control strategy, neglecting the impact of machine pitch angle on tillage depth stability, resulting in uneven work quality and difficulty adapting to complex terrain and soil conditions. Furthermore, the traction resistance measured by the force sensor installed at the hinge between the implement and the three-point suspension exhibits significant errors compared to the actual traction resistance acting on the vehicle, and the detected values ​​show high-frequency vibrations. Summary of the Invention

[0003] This invention aims to solve the problems of slow response, low accuracy, and reliance on force sensors to estimate load, which are easily affected by machine vibration and sudden changes in soil resistance. It proposes an electric three-point suspension rotary tiller leveling and tillage depth adjustment device and a method for tillage depth adjustment.

[0004] The technical solution adopted in this invention is as follows:

[0005] This invention relates to an electric three-point suspension rotary tiller leveling and tillage depth adjustment device, comprising a leveling cylinder, an upper pull rod, an upper swing arm, a lifting cylinder, and a lower pull rod. Two lower pull rods are symmetrically arranged on both sides of the chassis's symmetrical plane, one end of each rod being hinged to the frame via a ball joint, and the other end being connected to a ball joint. The two ball joints and two hinge shafts form sliding pairs. The frame is fixed to the chassis. The middle of each lower pull rod is hinged to the bottom of a leveling cylinder, and the tops of both leveling cylinders are hinged to one end of the upper swing arm. The other end of the upper swing arm is hinged to the frame. An angle sensor is installed on the second hinge shaft between the swing arm and the frame; the bottom end of the lifting cylinder is hinged to the chassis, and the top end is hinged to the middle of the upper swing arm; a ball joint is connected to the top end of the upper pull rod, and the ball joint and the hinge shaft form a sliding pair, with the hinge shaft fixed to the frame; a tilt sensor is installed on the fourth hinge shaft between the upper pull rod and the rotary tiller, and the tilt sensor is located on the symmetrical plane of the chassis; the signal output ends of both the angle sensor and the tilt sensor are connected to the control module, and the lifting cylinder and the leveling cylinder are both controlled by the control module; the tilt sensor is a dual-axis sensor.

[0006] Preferably, the connection method of the pull rod and the frame being hinged by a ball joint is replaced by: the pull rod is connected to a ball joint, the ball joint and the hinge shaft form a sliding pair, and the hinge shaft is fixed on the frame; the connection method of the pull rod and the leveling cylinder being hinged is replaced by: the support hole opened in the pull rod and the support shaft fixed at the bottom of the leveling cylinder are clearance fit.

[0007] This invention relates to a method for leveling and adjusting tillage depth of an electrically powered three-point suspension rotary tiller, as detailed below:

[0008] Two hinge shafts are fixed at two mounting positions on the rotary tiller, and the bottom end of the upper pull rod is hinged to the third mounting position on the rotary tiller. The pitch and lateral tilt angles of the rotary tiller are monitored in real time by a dual-axis tilt sensor. First, the two leveling electric cylinders are triggered based on the lateral tilt angle. The two leveling electric cylinders differentially adjust the extension compensation amount to restore the lateral tilt angle of the rotary tiller to 0. Then, an automatic tillage depth control strategy based on the coordination of the rotary tiller motor current and the rotary tiller posture is constructed. The pitch angle of the rotary tiller is monitored in real time by the dual-axis tilt sensor, and the lifting electric cylinder is dynamically adjusted to compensate for the pitch angle in combination with the real-time data of the rotary tiller motor current.

[0009] Preferably, the leveling electric cylinder's extension / retraction compensation amount Let W be the lateral tilt angle of the rotary tiller, and W be the distance between the two leveling cylinders. The lateral tilt angle is defined as positive when the rotary tiller is tilted upwards on the left and downwards on the right, and the compensation amount is also positive when the leveling cylinders extend. Therefore, the positive and negative values ​​of the compensation amount of the left leveling cylinder are consistent with the positive and negative values ​​of the lateral tilt angle, while the positive and negative values ​​of the compensation amount of the right leveling cylinder are opposite to the positive and negative values ​​of the lateral tilt angle. Specifically, when the two leveling cylinders differentially adjust the extension and retraction compensation amount, the two lower levers swing up and down, causing the first hinge shaft on the rotary tiller to move left and right relative to the second ball hinge. The second ball hinge rotates, and the third ball hinge on the upper lever rotates and moves left and right relative to the third hinge shaft, causing the rotary tiller to sway left and right.

[0010] Preferably, an automatic tillage depth control strategy based on the coordination of rotary tiller motor current and rotary tiller attitude is constructed. The pitch angle of the rotary tiller is monitored in real time by dual-axis tilt sensors, and the lift cylinder is dynamically adjusted to compensate for the pitch angle in conjunction with real-time rotary tiller motor current data. Specifically, as follows:

[0011] First, the positional tillage depth H1 is obtained by monitoring the pitch angle of the rotary tiller using a dual-axis tilt sensor and by establishing a linear relationship between the pitch angle and tillage depth. Simultaneously, the mechanical tillage depth H2 is obtained by analyzing the rotary tiller motor current and establishing a linear relationship between the current and tillage depth. Then, the equivalent tillage depth H is calculated by controlling the ratio of H1 to H2 using a comprehensive coefficient.

[0012] H = αH1 + (1-α)H2

[0013] Next, on the one hand, the tillage depth compensation amount ΔH = LL·cos(θ) is calculated based on the pitch angle θ of the rotary tiller, where L is the height of the tiller. The compensated tillage depth H′ = H + ΔH is also calculated based on the tillage depth compensation amount ΔH. On the other hand, combined with the upper swing arm rotation angle signal measured by the angle sensor, the lifting electric cylinder is controlled to drive the upper swing arm to rotate, which drives the two leveling electric cylinders, the two lower levers, the upper lever and the rotary tiller to rise and fall, so that the upper swing arm rotation angle measured by the angle sensor is equal to the pitch angle θ of the rotary tiller, thereby adjusting the actual tillage depth of the rotary tiller to the compensated tillage depth H′.

[0014] Finally, based on the deviation between the compensated tillage depth H′ and the set tillage depth, the extension and retraction of the lifting electric cylinder are adjusted to adjust the tillage depth compensation amount ΔH, so that the deviation between the compensated tillage depth H′ and the set tillage depth is within the threshold.

[0015] More preferably, a fuzzy PID control system based on a beetle whisker search optimization algorithm to improve the fuzzy PID control algorithm is constructed in the control module. This system includes a fuzzy PID controller, which comprises a fuzzy controller and a PID controller. The fuzzy PID control system adjusts the extension / retraction of the electric cylinder based on the deviation between the compensated tillage depth H′ and the set tillage depth. Furthermore, the fuzzy PID control system incorporates a beetle whisker search optimization algorithm to adjust the proportional factor K of the fuzzy PID controller. △p K △i and K △d Optimize.

[0016] More preferably, the process of adjusting the extension and retraction of the lifting cylinder based on the deviation between the compensated tillage depth H′ and the set tillage depth using a fuzzy PID control system is as follows: First, the output value y(t) of the compensated tillage depth H′ is calculated in real time and compared with the set tillage depth value x(t) to generate a deviation signal E and its derivative EC, which serve as two input variables for the fuzzy controller; the fuzzy controller ultimately dynamically outputs the proportional coefficient K. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d Then, according to △K p , △K i , △K d Calculate the proportionality coefficient K p Integral coefficient K i and differential coefficient K d Three PID parameters are transmitted to the PID controller, which calculates and outputs a control quantity to adjust the extension and retraction of the electric cylinder. The proportional coefficient K... p Integral coefficient K i and differential coefficient K d The calculation is as follows:

[0017]

[0018] Among them, K' p K' i K' d The proportionality coefficient K p Integral coefficient K i and differential coefficient K d The initial value of K △P K △i K △d The proportionality coefficient K p Integral coefficient K i and differential coefficient K d The corresponding scaling factor.

[0019] More preferably, the fuzzy controller is constructed as follows: First, the deviation signal E and its derivative EC are defined as the two input variables of the fuzzy controller, and the proportional coefficient K is defined. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d As the three output variables of the fuzzy controller, the membership functions and universe of discourse of the input and output variables are set in the editor. Based on the fuzzy control rules, the fuzzy control rules are written in the rule-making interface of the editor. Finally, the centroid method is selected as the defuzzification strategy for the fuzzy controller, and the proportional coefficient K is obtained. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d .

[0020] More preferably, the proportionality coefficient K p Correction amount △K p Integral coefficient K i Correction amount △K i Or differential coefficient K d Correction amount △K d The calculation using the centroid method is as follows:

[0021]

[0022] Where: x0 is the output variable of the fuzzy controller; x i is the element value in the fuzzy universe of discourse of the output variable; n is the number of elements in the fuzzy universe of discourse of the output variable; A(x i ) is the output variable in xi The membership function value at the corresponding element.

[0023] More preferably, the longhorn beetle search optimization algorithm optimizes the scaling factor K of the fuzzy PID controller. △p K △i and K △d The optimization process is as follows: The dimensions M = 3, the maximum number of iterations, the initial search step size S0, the initial distance d0 from the beetle's centroid to its whiskers, the decay coefficient h0, and K are set. △P K △i K △d The range of values ​​for is determined by updating the global optimal position of the beetle's centroid with the goal of minimizing the fitness value of the fitness function F(). During the iteration process, if the fitness value threshold or the termination condition of the maximum number of iterations is not met, the global optimal position of the beetle's centroid, the search direction, the search step size, and the minimum global fitness value are continuously updated, and the scaling factor K is also updated. △P K △i K △d This continues until the termination condition is met. The coordinates of the longhorn beetle's whiskers are calculated as follows:

[0024]

[0025] Where: P r P l Let P be the coordinates of the left and right longhorn beetle whiskers. t Let this be the position of the centroid of the longhorn beetle at the t-th iteration. Let d be a unit random vector, representing the distance d between the centroid and the whiskers of the beetle at the t-th iteration. t =h0d t-1 The search step size S in the t-th iteration t =h0S t-1 `sign()` is the sign function. When updating the global optimal position and global fitness minimum of the beetle's centroid, the individual beetle's centroid is moved to P... t+1 The fitness value F(P) of the location t+l The minimum current fitness value F of the longhorn beetle individual best Comparison, if F(P) t+l ) <F best Then update the minimum current fitness value F of the longhorn beetle individual. best =F(P t+l Update the current optimal position P of the longhorn beetle individual. best =P t+1 The minimum fitness value of the individual beetle is assigned to the minimum fitness value of the global system, and the optimal position of the individual beetle is assigned to the optimal position of the beetle's centroid in the global system; otherwise, F is maintained. best and P best constant.

[0026] The fitness value of the fitness function is calculated as follows:

[0027]

[0028] Where e(t) is the value of the deviation signal E in the t-th iteration.

[0029] The beneficial effects of this invention are:

[0030] 1. This invention proposes an electric three-point suspension rotary tiller leveling and tillage depth adjustment device. The control module receives the lateral tilt angle signal of the rotary tiller measured by a tilt sensor. Two leveling electric cylinders independently adjust the angles of the two lower levers to adjust the lateral tilt angle of the rotary tiller. The device also receives the pitch angle signal of the rotary tiller measured by the tilt sensor, and combines it with the upper swing arm angle signal measured by an angle sensor. A lifting electric cylinder drives the upper swing arm to rotate, raising and lowering the rotary tiller to adjust the compensated tillage depth. Based on the deviation between the compensated tillage depth and the set tillage depth, the extension and retraction of the lifting electric cylinder are adjusted to keep the deviation within a threshold value, thus achieving closed-loop adjustment of the tillage depth and attitude of the rotary tiller. The three mounting positions of the rotary tiller form a bi-symmetrical three-point suspension structure. Under no lateral load conditions, the structures on both sides exhibit synchronous movement characteristics during lifting, resulting in uniform force distribution. Among them, the ball joints on the two pull rods and the two hinge shafts form a sliding pair, and the two hinge shafts are fixed at the two mounting positions of the rotary tiller. The ball joint on the upper pull rod and the hinge shaft form a sliding pair, and the hinge shaft is fixed on the frame. This ingenious design ensures that the rotary tiller does not interfere with each other when adjusting the pitch angle and lateral tilt angle.

[0031] 2. This invention proposes a method for adjusting tillage depth. First, the lateral tilt angle of the rotary tiller is monitored in real time, triggering the action of two leveling electric cylinders. The two leveling electric cylinders differentially adjust the extension compensation amount to restore the lateral tilt angle of the rotary tiller to 0. Then, based on an automatic tillage depth control strategy that coordinates motor current and rotary tiller posture, the pitch angle of the rotary tiller is monitored in real time by a dual-axis tilt sensor. Combined with real-time data of the rotary tiller motor current, the equivalent tillage depth is calculated according to the ratio of positional tillage depth to mechanical tillage depth based on a comprehensive coefficient. The real-time positional tillage depth is obtained through the pitch angle of the rotary tiller monitored by the dual-axis tilt sensor and the calibrated linear relationship between the pitch angle and the tillage depth. The real-time mechanical tillage depth is obtained through the rotary tiller motor current and the calibrated linear relationship between the current and the tillage depth. Next, on the one hand, the tillage depth compensation is calculated based on the pitch angle of the rotary tiller, and the compensated tillage depth is calculated based on the compensation amount. On the other hand, combined with the upper swing arm rotation signal measured by the angle sensor, the lifting cylinder is controlled to drive the rotary tiller to rise and fall, so that the upper swing arm rotation angle is equal to the pitch angle of the rotary tiller, thereby adjusting the actual tillage depth of the rotary tiller to the compensated tillage depth. Finally, based on the deviation between the compensated tillage depth and the set tillage depth, the extension and retraction of the lifting cylinder is adjusted to adjust the tillage depth compensation amount, so that the deviation between the compensated tillage depth and the set tillage depth is within the threshold, thereby reducing the influence of soil resistance and machine posture on the tillage depth and improving the quality of operation. In scenarios with significant terrain undulation, location-based tillage depth, relying on static assumptions and susceptible to attitude interference, cannot accurately reflect the actual tillage depth. In contrast, mechanical tillage depth, directly linked to the load via current, possesses stronger dynamic adaptability. By reducing the comprehensive coefficient, it can prioritize responding to real-time feedback from mechanical tillage depth, reducing control errors caused by terrain undulations, thereby improving tillage depth stability and energy efficiency. When soil texture exhibits significant spatial variation, the comprehensive coefficient is increased to enhance the stability of location control and ensure consistency in tillage depth.

[0032] 3. The tillage depth adjustment method of this invention introduces the longhorn beetle whisker search optimization algorithm to optimize the proportional factor corresponding to the proportional coefficient, integral coefficient and derivative coefficient in the fuzzy controller. The optimized fuzzy PID algorithm is superior to the classic PID and ordinary fuzzy PID algorithms in terms of dynamic response characteristics, overshoot, and settling time. It significantly improves the control accuracy, dynamic response characteristics and anti-interference ability of the tillage depth automatic control system, and gives full play to the advantages of the fuzzy PID controller. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the leveling and tillage depth adjustment device of the present invention.

[0034] Figure 2 This is a schematic diagram of the right side of the leveling and tillage depth adjustment device of the present invention.

[0035] Figure 3 This is a simplified diagram of the leveling and tillage depth adjustment device of the present invention.

[0036] Figure 4 This is a control block diagram of the leveling and tillage depth adjustment method of the present invention.

[0037] Figure 5 This is the control block diagram of the fuzzy PID control system in this invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings.

[0039] like Figure 1 , Figure 2 and Figure 3 As shown, the leveling and tillage depth adjustment device for an electric three-point suspension rotary tiller includes a leveling cylinder 2, an upper pull rod 3, an upper swing arm 4, a lifting cylinder 8, and a lower pull rod 9. Two lower pull rods 9 are symmetrically arranged on both sides of the chassis's symmetrical plane. One end of each lower pull rod is hinged to the frame via a ball joint, and the other end is connected to a ball joint. The two ball joints 2 and two hinge shafts 1 form sliding pairs, and the two hinge shafts 1 are fixed at two mounting positions on the rotary tiller 1. The frame is fixed to the chassis. The middle of each lower pull rod 9 is hinged to the bottom end of a leveling cylinder 2. The tops of the two leveling electric cylinders 2 are hinged to one end of the upper swing arm 4, and the other end of the upper swing arm 4 is hinged to the frame. An angle sensor 5 is installed on the hinge shaft 2 between the upper swing arm 4 and the frame. The bottom of the lifting electric cylinder 8 is hinged to the chassis, and the top is hinged to the middle of the upper swing arm 4. The bottom of the upper pull rod 3 is hinged to the third mounting position of the rotary tiller 1, and the top is connected to a ball joint 3. The ball joint 3 and the hinge shaft 3 form a sliding pair, and the hinge shaft 3 is fixed to the frame. An tilt sensor 6 is installed on the hinge shaft 4 between the upper pull rod 3 and the rotary tiller 1. The tilt sensor 6 is located on the chassis. On the symmetrical plane; the signal output terminals of angle sensor 5 and tilt sensor 6 are both connected to the control module (which can be an ECU control unit). The lifting cylinder 8 and leveling cylinder 2 are both controlled by the control module, which is integrated into the control cabinet 7. The tilt sensor 6 is a dual-axis MEMS sensor used to measure the pitch angle (also the frame pitch angle) and lateral tilt angle of the rotary tiller 1. The control module receives the lateral tilt angle signal of the rotary tiller 1 measured by the tilt sensor 6 and realizes the independent angle of the two pull rods 9 through the two leveling cylinders 2. The adjustment mechanism controls the lateral tilt angle of the rotary tiller 1. It receives the pitch angle signal from the tilt sensor 6 and the rotation angle signal from the upper swing arm 4 from the angle sensor 5. The upper swing arm 4 is rotated via the lifting cylinder 8, causing the rotary tiller 1 to rise and fall, thus adjusting the compensated tillage depth. Based on the deviation between the compensated tillage depth and the set tillage depth, the extension and retraction of the lifting cylinder 8 are adjusted to keep the deviation within a threshold value, thereby achieving closed-loop adjustment of the tillage depth and attitude (lateral tilt angle) of the rotary tiller 1. The three mounting positions of the rotary tiller 1 form a symmetrical three-point suspension structure. Under no lateral load conditions, the structures on both sides exhibit synchronous movement characteristics during lifting, resulting in uniform force distribution.

[0040] In a preferred embodiment, the connection between the pull rod 9 and the frame via a ball joint is replaced by: the pull rod 9 is connected to a ball joint, the ball joint and the hinge shaft form a sliding pair, and the hinge shaft is fixed to the frame; the connection between the pull rod 9 and the leveling cylinder 2 is replaced by: the support hole in the pull rod 9 and the support shaft fixed at the bottom of the leveling cylinder 2 are clearance-fitted. In this way, when the pull rod 9 swings up and down, it can also sway left and right within the allowable clearance range, avoiding excessive force and damage caused by interference in the movement of the pull rod 9.

[0041] This invention relates to a method for leveling and adjusting tillage depth of an electrically powered three-point suspension rotary tiller, as detailed below:

[0042] The rotary tiller motor current of rotary tiller 1 (the control module can directly read the current signal of the rotary tiller motor) is used as the working condition monitoring parameter. Utilizing the relationship between the rotary tiller motor current and tillage depth (which is approximately linear), the rotary tiller motor current is used to replace the traditional force sensor, achieving accurate real-time load measurement during operation. When rotary tiller 1 is working, the rotary blades cut into the soil, and the soil resistance is converted into torque that the rotary tiller motor needs to overcome. The greater the load on the rotary tiller motor, the higher the current required to drive the rotary blades to rotate; therefore, the increase or decrease in current directly reflects the change in soil resistance. According to the working principle of the motor, the output torque (T) of the motor is proportional to the current (I), and the relationship is as follows:

[0043] T=K t ·I

[0044] Among them, K t Here, represents the torque constant of the motor (unit: N·m / A). When the rotary tiller blades cut into the soil, the load created by soil resistance is converted into torque that the rotary tiller motor needs to overcome. Therefore, the real-time change in current directly reflects the magnitude of the external load. Increasing the tillage depth (H2) leads to a larger contact area between the rotary tiller blades and the soil, thereby increasing the resistance. Under the same soil conditions, the tillage depth and load (current) are approximately linearly related. Therefore, by establishing a current-tillage depth relationship model through calibration experiments, indirect measurement of tillage depth can be achieved. Here, the least squares method is used to perform linear regression on the calibration experimental data to establish a relationship model between current (I) and tillage depth (H2), converting the current into tillage depth H2.

[0045] However, tillage depth is also closely related to the posture of the rotary tiller. For example, if the rotary tiller is tilted to the left or right (the lateral tilt angle is not 0), it will result in a larger tillage depth on one side and a smaller tillage depth on the other side. Changes in the pitch angle of the rotary tiller will also lead to changes in tillage depth.

[0046] This invention uses a dual-axis tilt sensor to monitor the pitch angle (forward / backward tilt) and lateral tilt angle (left / right tilt) of the rotary tiller 1 in real time. First, based on the lateral tilt angle φ, two leveling electric cylinders are triggered. These two cylinders differentially adjust the extension / retraction compensation to restore the rotary tiller's lateral tilt angle to 0. The extension / retraction compensation of the leveling electric cylinders... W represents the distance between the two leveling cylinders. It can be stipulated that when the rotary tiller is tilted upwards on the left and downwards on the right, the lateral tilt angle is positive, and the compensation amount is positive when the leveling cylinder extends. Therefore, the positive and negative values ​​of the compensation amount of the left leveling cylinder are consistent with the positive and negative values ​​of the lateral tilt angle, while the positive and negative values ​​of the compensation amount of the right leveling cylinder are opposite to the positive and negative values ​​of the lateral tilt angle. Specifically, when the two leveling cylinders differentially adjust the extension and retraction compensation amount, the two lower levers 9 swing up and down, causing the hinge shaft one on the rotary tiller 1 to move left and right relative to the ball hinge two. The ball hinge two rotates, and the ball hinge three on the upper lever 3 rotates and moves left and right relative to the hinge shaft three, causing the rotary tiller to sway left and right.

[0047] After the lateral tilt angle of the rotary tiller returns to 0, this invention constructs an automatic tillage depth control strategy based on the coordination of motor current and rotary tiller posture. The pitch angle of the rotary tiller 1 is monitored in real time by a dual-axis tilt sensor, and the lifting cylinder 8 is dynamically adjusted based on the real-time data of the rotary tiller motor current to compensate for the pitch angle, thereby reducing the impact of soil resistance and tillage posture on tillage depth. Specifically, as follows:

[0048] like Figure 4 As shown, an automatic tillage depth control strategy based on the coordination of motor current and rotary tiller attitude is adopted. Force-position integrated control is used to achieve precise adjustment of the tiller's working height, with tillage depth compensation as the core control signal. Specifically: First, the positional tillage depth H1 is obtained by monitoring the pitch angle of rotary tiller 1 using dual-axis tilt sensors and the calibrated linear relationship between the pitch angle and tillage depth. Simultaneously, the mechanical tillage depth H2 is obtained by monitoring the rotary tiller motor current and the calibrated linear relationship between the current and tillage depth. Then, the equivalent tillage depth H is calculated based on the ratio of H1 to H2 using a comprehensive coefficient.

[0049] H = αH1 + (1-α)H2

[0050] The equivalent tillage depth H calculation method adopted is a force-position integrated control strategy based on a comprehensive coefficient. This control strategy introduces a comprehensive coefficient α (0≤α≤1) as a weight parameter for force-position control. This coefficient represents the proportion of position control in the integrated control system. By adjusting the weight ratio of different control inputs through the comprehensive coefficient, the fusion and priority allocation of multi-source data are achieved. Specifically, when the α value approaches 1, it exhibits a regulation characteristic dominated by position control, while a decrease in the α value enhances the regulation effect of current (reflection of load) feedback. In scenarios with large terrain undulations, positional tillage depth, due to its reliance on static assumptions and susceptibility to attitude interference, cannot accurately reflect the actual tillage depth. In contrast, mechanical tillage depth, directly related to the load through current, has stronger dynamic adaptability. By reducing the α value, the real-time feedback of mechanical tillage depth can be prioritized, reducing control errors caused by terrain undulations and thus improving tillage depth stability and energy efficiency. When soil texture varies significantly in space, the α value is increased to strengthen the stability of position control and ensure the consistency of tillage depth.

[0051] Next, on the one hand, the tillage depth compensation amount ΔH = LL·cos(θ) is calculated based on the pitch angle θ of the rotary tiller 1, where L is the height of the tiller. The compensated tillage depth H′ = H + ΔH is also calculated based on the tillage depth compensation amount ΔH. On the other hand, combined with the rotation angle signal of the upper swing arm 4 measured by the angle sensor 5, the lifting cylinder 8 is controlled to drive the upper swing arm 4 to rotate, which drives the two leveling cylinders 2, the two lower levers 9, the upper lever 3 and the rotary tiller 1 to rise and fall, so that the rotation angle of the upper swing arm 4 measured by the angle sensor 5 is equal to the pitch angle θ of the rotary tiller 1, thereby adjusting the actual tillage depth of the rotary tiller 1 to the compensated tillage depth H′.

[0052] Finally, based on the deviation between the compensated tillage depth H′ and the set tillage depth, the extension and retraction of the lifting electric cylinder 8 are adjusted to adjust the tillage depth compensation amount ΔH, so that the deviation between the compensated tillage depth H′ and the set tillage depth is within the threshold.

[0053] As a preferred embodiment, such as Figure 5 As shown, a fuzzy PID control system based on a beetle whisker search optimization algorithm to improve the fuzzy PID control algorithm is constructed in the control module. This system includes a fuzzy PID controller, which in turn contains both a fuzzy controller and a PID controller. The fuzzy PID control system uses feedback to adjust the extension / retraction of the electric cylinder 8 based on the deviation between the compensated tillage depth H′ and the set tillage depth. Furthermore, the fuzzy PID control system incorporates a beetle whisker search optimization algorithm to improve the proportional factor K of the fuzzy PID controller. △p K △i and K △d Optimization is carried out to improve the control accuracy, dynamic response characteristics and anti-interference ability of automatic tillage depth control, thereby ensuring that the fuzzy PID controller always works in the optimal state, giving full play to the advantages of the fuzzy PID controller and significantly improving control performance.

[0054] Specifically, the process of adjusting the extension and retraction of the lifting cylinder 8 based on the deviation between the compensated tillage depth H′ and the set tillage depth using a fuzzy PID control system is as follows: First, the output value y(t) of the compensated tillage depth H′ is calculated in real time and compared with the set tillage depth value x(t) to generate a deviation signal E and its derivative EC, which serve as the two input variables of the fuzzy controller; the fuzzy controller ultimately dynamically outputs the proportional coefficient K. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d Then, according to △K p , △K i , △K d Calculate the proportionality coefficient K p Integral coefficient K i and differential coefficient K d Three PID parameters are fed to the PID controller, which calculates and outputs a control quantity to adjust the extension and retraction of the lifting electric cylinder 8. The proportional coefficient K... p Integral coefficient K i and differential coefficient K d The calculation is as follows:

[0055]

[0056] Among them, K' p K' i K' d The proportionality coefficient K p Integral coefficient K i and differential coefficient K d The initial value of K △P K △i K △d The proportionality coefficient K p Integral coefficient K i and differential coefficient K d The corresponding scaling factor. Where K... △P Adjust the response speed of the extension and retraction of the electric cylinder 8; K △i Adjust the cumulative compensation force to maintain the intensity of the increased pressure of electric cylinder 8; K △d Adjusting the system damping affects the timing of the acceleration and deceleration of the lifting electric cylinder 8. When significant tillage depth deviation occurs, appropriately increase K. △P It can significantly accelerate and improve the response speed of the electric cylinder 8's extension and retraction. When the tillage depth deviation is within a small range, K can be appropriately reduced. △P This facilitates fine-tuning, while appropriately increasing K. △iThis maintains the steady-state performance of the fuzzy PID control system. Furthermore, considering the significant inertia of the lifting cylinder 8 during its movement, to prevent overshoot, K... △d The value of K should not be too large; a smaller value should be used instead. △d The value can also significantly improve the anti-interference performance of the fuzzy PID control system.

[0057] The fuzzy controller is constructed as follows: First, define the deviation signal E and its derivative EC as the two input variables of the fuzzy controller, and define the proportional coefficient K. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d As the three output variables of the fuzzy controller, the membership functions and universe of discourse of the input and output variables are set in the editor. Based on the fuzzy control rules, the fuzzy control rules are written in the rule-making interface of the editor. Finally, considering both control accuracy and computational efficiency, the centroid method is selected as the defuzzification strategy for the fuzzy controller, and the proportional coefficient K is obtained. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d In fuzzy PID control systems, variables are described using fuzzy language. When dividing the range of fuzzy language variable values, it is necessary to strictly follow standard rules in engineering practice. This invention defines the universe of discourse for input and output variables as seven-level linguistic variables {negative large (NB), negative medium (NM), negative small (NS), zero (ZO), positive small (PS), positive medium (PM), positive large (PB)}, and determines the basic universe of discourse for the deviation signal E and its derivative EC as [-100mm, +100mm]. The fuzzy universe of discourse after quantization is [-6, 6]. The proportional coefficient K is then evaluated using the Control System Tuner toolbox. p Integral coefficient K i and differential coefficient K d The three PID parameters were initially tuned to determine the correction amount ΔK. p , △K i and △K d The basic universes of discourse are [-30,30], [-50,50] and [-1,1], respectively, and the fuzzy universes of discourse after quantization are all set to [-6,6]. The membership functions of the input and output variables are all triangularly distributed (triangular membership function).

[0058] Among them, ΔK is constructed based on the deviation signal E and its derivative EC. p , △K i and △K d The fuzzy control rules are as follows:

[0059] Table 1 △K p Fuzzy control rules

[0060]

[0061]

[0062] Table 2 △K i Fuzzy control rules

[0063]

[0064] Table 3 △K d Fuzzy control rules

[0065]

[0066] proportionality coefficient K p Correction amount △K p Integral coefficient K i Correction amount △K i Or differential coefficient K d Correction amount △K d The calculation using the centroid method is as follows:

[0067]

[0068] Where: x0 is the output variable of the fuzzy controller (proportional coefficient K) p Correction amount △K p Integral coefficient K i Correction amount △K i Or differential coefficient K d Correction amount △K d );x i is the element value in the fuzzy universe of discourse of the output variable; n is the number of elements in the fuzzy universe of discourse of the output variable; A(x i ) is the output variable in x i The membership function value at the corresponding element.

[0069] To improve the control accuracy, dynamic response characteristics, and anti-interference capability of the automatic tillage depth control system and fully leverage the advantages of the fuzzy PID controller, this invention introduces a beetle whisker search (BAS) optimization algorithm to optimize the scaling factor K. △P K △i K △dThe optimization process is as follows: Dimension M = 3, maximum number of iterations Tmax = 100, initial search step size S0 = 2, initial distance from the beetle's centroid to its whiskers d0 = 2, attenuation coefficient h0 = 0.95, K... △P K △i K △d The value range is [-100, 100]. The goal is to update the global optimal position of the beetle's centroid with the minimum fitness value of the fitness function F(). During the iteration process, if the fitness value threshold or the termination condition of the maximum number of iterations is not met, the global optimal position of the beetle's centroid, the search direction (unit random vector), the search step size, and the minimum global fitness value are continuously updated, and the scaling factor K is also updated. △P K △i K △d The process continues until the termination condition is met. The coordinates of the longhorn beetle are calculated as follows:

[0070]

[0071] Where: P r P l Let P be the coordinates of the left and right longhorn beetle whiskers. t Let this be the position of the centroid of the longhorn beetle at the t-th iteration. Let d be a unit random vector (representing the random search direction of the beetle's whiskers), and let d be the distance d between the beetle's centroid and its whiskers at the t-th iteration. t =h0d t-1 The search step size S in the t-th iteration t =h0S t-1 `sign()` is the sign function. When updating the global optimal position and global fitness minimum of the beetle's centroid, the individual beetle's centroid is moved to P... t+1 The fitness value F(P) of the location t+l The minimum current fitness value F of the longhorn beetle individual best Comparison, if F(P) t+l ) <F best Then update the minimum current fitness value F of the longhorn beetle individual. best =F(P t+l Update the current optimal position P of the longhorn beetle individual. best =P t+1 The minimum fitness value of the individual beetle is assigned to the minimum fitness value of the global system, and the optimal position of the individual beetle is assigned to the optimal position of the beetle's centroid in the global system. Otherwise, F is maintained. best and P best constant.

[0072] Unit random vector:

[0073]

[0074] Where: rnd(M,1) is a randomly generated M-dimensional vector, and ||||2 is the Euclidean norm.

[0075] A lower fitness value is better, as it is used to evaluate the quality of the current position of the beetle's centroid. The fitness value is calculated as follows:

[0076]

[0077] Where e(t) is the value of the deviation signal E in the t-th iteration.

Claims

1. A leveling and tillage depth adjustment method based on an electric three-point suspension rotary tiller leveling and tillage depth adjustment device, wherein the electric three-point suspension rotary tiller leveling and tillage depth adjustment device includes an upper pull rod, an upper swing arm, a lifting electric cylinder, and a lower pull rod, characterized in that: It also includes leveling electric cylinders; two pull rods are symmetrically arranged on both sides of the symmetrical plane of the chassis, one end of each is hinged to the frame via a ball joint, and the other end is connected to a ball joint, the two ball joints and two hinge shafts forming sliding pairs; the frame is fixed to the chassis; the middle of each pull rod is hinged to the bottom of a leveling electric cylinder, the top of each of the two leveling electric cylinders is hinged to one end of an upper swing arm, the other end of the upper swing arm is hinged to the frame, and an angle sensor is provided on the hinge shaft of the upper swing arm and the frame; The bottom of the lifting cylinder is hinged to the chassis, and the top is hinged to the middle of the upper swing arm. A ball joint (or hinge shaft) is connected to the top of the upper pull rod, forming a sliding pair with the ball joint (or hinge shaft) (or hinge shaft) (or hinge shaft) (or hinge shaft) fixed to the frame). A tilt sensor is installed on the hinge shaft (or hinge shaft) between the upper pull rod and the rotary tiller, located on the symmetrical plane of the chassis. The signal outputs of both the angle sensor and the tilt sensor are connected to the control module, which controls both the lifting cylinder and the leveling cylinder. The tilt sensor is a dual-axis sensor. The method is as follows: Two hinge shafts are fixed at two mounting positions on the rotary tiller, and the bottom end of the upper pull rod is hinged to the third mounting position on the rotary tiller. The pitch and lateral tilt angles of the rotary tiller are monitored in real time by a dual-axis tilt sensor. First, the two leveling electric cylinders are triggered based on the lateral tilt angle. The two leveling electric cylinders differentially adjust the extension compensation amount to restore the lateral tilt angle of the rotary tiller to 0. Then, an automatic tillage depth control strategy based on the coordination of the rotary tiller motor current and the rotary tiller posture is constructed. The pitch angle of the rotary tiller is monitored in real time by the dual-axis tilt sensor, and the lifting electric cylinder is dynamically adjusted to compensate for the pitch angle in combination with the real-time data of the rotary tiller motor current.

2. The leveling and tillage depth adjustment method of the electric three-point suspension rotary tiller leveling and tillage depth adjustment device according to claim 1, characterized in that: The connection between the pull rod and the frame via ball joint 1 is replaced with: the pull rod is connected to ball joint 1, ball joint 1 and hinge shaft 4 form a sliding pair, and hinge shaft 4 is fixed on the frame; the connection between the pull rod and the leveling cylinder is replaced with: the support hole in the pull rod and the support shaft fixed at the bottom of the leveling cylinder are clearance fitted.

3. The leveling and tillage depth adjustment method of the electric three-point suspension rotary tiller leveling and tillage depth adjustment device according to claim 1, characterized in that: Leveling the electric cylinder extension compensation amount , Let W be the lateral tilt angle of the rotary tiller, and W be the distance between the two leveling cylinders. It is stipulated that the lateral tilt angle is positive when the rotary tiller is tilted to the upper left and lower right, and the compensation amount is positive when the leveling cylinders extend. Therefore, the positive and negative values ​​of the compensation amount of the left leveling cylinder are the same as the positive and negative values ​​of the lateral tilt angle, and the positive and negative values ​​of the compensation amount of the right leveling cylinder are opposite to the positive and negative values ​​of the lateral tilt angle. When the two leveling cylinders differentially adjust the extension and retraction compensation amount, the two pull rods swing up and down, causing the hinge shaft one on the rotary tiller to move left and right relative to the ball hinge two. The ball hinge two rotates, and the ball hinge three on the upper pull rod rotates and moves left and right relative to the hinge shaft three, causing the rotary tiller to sway left and right.

4. The leveling and tillage depth adjustment method of the electric three-point suspension rotary tiller leveling and tillage depth adjustment device according to claim 1, characterized in that: An automatic tillage depth control strategy based on the coordination of rotary tiller motor current and rotary tiller attitude is constructed. The pitch angle of the rotary tiller is monitored in real time by dual-axis tilt sensors, and the lift cylinder is dynamically adjusted to compensate for the pitch angle by combining real-time data of the rotary tiller motor current. The specific details are as follows: First, the positional tillage depth H1 is obtained by monitoring the pitch angle of the rotary tiller using a dual-axis tilt sensor and by establishing a linear relationship between the pitch angle and tillage depth. Simultaneously, the mechanical tillage depth H2 is obtained by analyzing the rotary tiller motor current and establishing a linear relationship between the current and tillage depth. Then, the equivalent tillage depth H is calculated by controlling the ratio of H1 to H2 using a comprehensive coefficient. Next, based on the pitch angle of the rotary tiller... Calculate the amount of compensation for tillage depth Where L is the height of the implement, and the compensation amount is based on the tillage depth. Calculate the tillage depth after compensation On the other hand, by combining the upper swing arm rotation angle signal measured by the angle sensor, the lifting electric cylinder is controlled to drive the upper swing arm to rotate, which in turn drives the two leveling electric cylinders, the two lower levers, the upper lever, and the rotary tiller to rise and fall, so that the upper swing arm rotation angle measured by the angle sensor is equal to the rotary tiller's pitch angle. This adjusts the actual tillage depth of the rotary tiller to the compensated tillage depth. ; Finally, based on the compensated tillage depth The deviation from the set tillage depth is fed back to adjust the extension and retraction of the electric cylinder, thereby adjusting the tillage depth compensation. To increase the depth of cultivated land after compensation The deviation from the set tillage depth is within the threshold.

5. The leveling and tillage depth adjustment method of the electric three-point suspension rotary tiller leveling and tillage depth adjustment device according to claim 4, characterized in that: A fuzzy PID control system based on an improved fuzzy PID control algorithm using a longhorn beetle whisker search optimization algorithm is constructed in the control module. This system includes a fuzzy PID controller, which comprises a fuzzy controller and a PID controller. The fuzzy PID control system is used to control the tillage depth after compensation. The deviation from the set tillage depth is adjusted by feedback to increase the extension and retraction of the electric cylinder. Furthermore, the fuzzy PID control system incorporates a beetle whisker search optimization algorithm to optimize the proportional factor K of the fuzzy PID controller. △p K △i and K △d Optimize.

6. The leveling and tillage depth adjustment method of the electric three-point suspension rotary tiller leveling and tillage depth adjustment device according to claim 5, characterized in that: The fuzzy PID control system is used to achieve the calculation based on the compensated tillage depth. The process of adjusting the extension and retraction of the electric cylinder to compensate for deviations from the set tillage depth is as follows: First, the tillage depth after compensation is calculated in real time. The output value y(t) is compared with the set tillage depth value x(t) to generate the deviation signal E and its derivative EC, which serve as the two input variables of the fuzzy controller; the fuzzy controller ultimately dynamically outputs the proportional coefficient K. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d Then, according to △K p , △K i , △K d Calculate the proportionality coefficient K p Integral coefficient K i and differential coefficient K d Three PID parameters are transmitted to the PID controller, which calculates and outputs a control quantity to adjust the extension and retraction of the lifting electric cylinder; the proportional coefficient K p Integral coefficient K i and differential coefficient K d The calculation is as follows: Among them, K' p K' i K' d The proportionality coefficient K p Integral coefficient K i and differential coefficient K d The initial value of K △P K △i K △d The proportionality coefficient K p Integral coefficient K i and differential coefficient K d The corresponding scaling factor.

7. The leveling and tillage depth adjustment method of the electric three-point suspension rotary tiller leveling and tillage depth adjustment device according to claim 5, characterized in that: The fuzzy controller is constructed as follows: First, the deviation signal E and its derivative EC are defined as the two input variables of the fuzzy controller, and the proportional coefficient K is defined. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d As the three output variables of the fuzzy controller, the membership functions and universe of discourse of the input and output variables are set in the editor. Based on the fuzzy control rules, the fuzzy control rules are written in the rule-making interface of the editor. Finally, the centroid method is selected as the defuzzification strategy for the fuzzy controller, and the proportional coefficient K is obtained. p Correction amount △K p Integral coefficient K i Correction amount △K i and differential coefficient K d Correction amount △K d .

8. The leveling and tillage depth adjustment method of the electric three-point suspension rotary tiller leveling and tillage depth adjustment device according to claim 7, characterized in that: proportionality coefficient K p Correction amount △K p Integral coefficient K i Correction amount △K i Or differential coefficient K d Correction amount △K d The calculation using the centroid method is as follows: Where: x0 is the output variable of the fuzzy controller; The element values ​​in the fuzzy universe of discourse of the output variable; The number of elements in the fuzzy universe of discourse of the output variable; For output variables in The membership function value at the corresponding element.

9. The leveling and tillage depth adjustment method of the electric three-point suspension rotary tiller leveling and tillage depth adjustment device according to claim 5, characterized in that: The longhorn beetle search optimization algorithm is used to optimize the scaling factor K of the fuzzy PID controller. △p K △i and K △d The optimization process is as follows: Set the dimension M=3, the maximum number of iterations, and the initial search step size. The initial distance from the center of mass of the longhorn beetle to the longhorn beetle must be attenuation coefficient and K △P K △i K △d The range of values ​​for the fitness function The goal is to minimize the fitness value and update the global optimal position of the beetle's centroid. During the iteration process, if the fitness value threshold or the termination condition of the maximum number of iterations is not met, the global optimal position of the beetle's centroid, the search direction, the search step size, and the minimum global fitness value are continuously updated, and the scaling factor K is also updated. △P K △i K △d The process continues until the termination condition is met; the coordinates of the longhorn beetle's whiskers are calculated as follows: in: , Let be the coordinates of the left and right longhorn beetle whiskers. Let this be the position of the centroid of the longhorn beetle at the t-th iteration. Let be a unit random vector, and be the distance between the centroid of the beetle and its whiskers at the t-th iteration. The search step size at the t-th iteration , The sign function; when updating the global optimal position and global fitness minimum of the beetle's centroid, the beetle's individual centroid is placed in... The fitness value F(P) of the location t+l The minimum current fitness value F of the longhorn beetle individual best Comparison, if F(P) t+l ) <F best Then update the minimum current fitness value F of the longhorn beetle individual. best = F(P t+l Update the current optimal position of the longhorn beetle individual. The minimum fitness value of the individual beetle is assigned to the minimum fitness value of the global system, and the optimal position of the individual beetle is assigned to the optimal position of the beetle's centroid in the global system; otherwise, F is maintained. best and constant; The fitness value of the fitness function is calculated as follows: Where e(t) is the value of the deviation signal E in the t-th iteration.

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