Seat active leveling method of waist-twisting tractor

Abstract

The invention relates to an active seat leveling method for a waist-twisting tractor, which comprises the following steps: acquiring pose parameters and path information of the tractor in real time, predicting a posture change trend of a seat mounting point caused by waist-twisting swing through a preset waist-twisting kinematics model, and generating a feedforward control signal; meanwhile, actual posture information of the seat and the vehicle body is obtained to generate a feedback control signal; and the feedforward control signal and the feedback control signal are fused, a cooperative control instruction is generated, a seat multi-degree-of-freedom adjusting mechanism is driven to roll or pitch, and therefore real-time and predictive dynamic stability of the posture of a driver is achieved. Through feedforward-feedback compound control, the response speed and stability of the leveling system are remarkably improved, and the riding comfort and operation safety of a driver are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of tractor seat leveling technology, and in particular to an active seat leveling method for a folding and twisting tractor. Background Technology

[0002] As a new type of agricultural machinery, folding and twisting tractors have received widespread attention and application in China in recent years. Folding and twisting tractors improve terrain adaptability through their folding and twisting mechanism; however, their swaying primarily responds to ground impacts, representing passive or simple active control, without considering the direct impact on the driver's posture. The vehicle's tilt causes the driver to tilt as well, requiring the driver to rely on abdominal and back strength to maintain balance, which can easily lead to fatigue.

[0003] Some advanced engineering machinery has intelligent seats with independent leveling functions, but their sensors usually only monitor the absolute posture of the seat itself or the frame. This is a follow-up compensation with a response lag. When the waist is twisted and swayed rapidly, the seat leveling action may be delayed, resulting in limited improvement in comfort. Summary of the Invention

[0004] In view of the aforementioned defects in existing tractor seat leveling technology, the purpose of this invention is to propose an active seat leveling method for folding and twisting tractors.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention is: a method for actively leveling the seat of a folding and twisting tractor, comprising:

[0006] Step S1: Initialize the control system;

[0007] Step S2: The attitude perception module collects pose parameters and path information in real time, including the swing angle and angular velocity of the hinge point, the inertial measurement data of the front and rear frames and seats, and the satellite navigation GNSS positioning data.

[0008] Step S3: The cooperative controller calculates the current road surface bump level and vehicle speed based on the pose parameters and path information collected by the attitude control module in step S2. If the current road surface bump level is greater than the preset bump threshold or the current vehicle speed is lower than the preset vehicle speed threshold, then proceed to step S4; otherwise, proceed to step S5.

[0009] Step S4: The collaborative controller generates a seat position adjustment command based solely on the deviation between the current seat posture and the target posture using a PID feedback control algorithm, and then executes step S6.

[0010] Step S5: The cooperative controller enters the feedforward-feedback cooperative predictive control mode and generates cooperative control commands;

[0011] Step S6: The collaborative controller sends the position adjustment command generated in step S4 or the collaborative control command generated in step S5 to the drive module, driving the multi-degree-of-freedom adjustment mechanism of the seat to perform tilt and pitch adjustments.

[0012] Furthermore, the initialization of the control system in step S1 includes setting the target posture angle of the seat, predictive control parameters, and various thresholds.

[0013] Furthermore, in step S2, the attitude perception module includes a flexure / torsion joint sensor, a vehicle inertial measurement unit (IMU), a seat attitude sensor, and a satellite navigation GNSS. The flexure / torsion joint sensor is mounted on the tractor's flexure / torsion hinge shaft to measure the swing angle and angular velocity of the flexure / torsion in real time. Two inertial measurement units (IMUs) are rigidly mounted on the tractor's front and rear frames to measure the vehicle's attitude, angular velocity, and acceleration, and are fused with the satellite navigation GNSS data using a Kalman filter algorithm. The seat attitude sensor is mounted on the adjustment platform base under the seat cushion to measure the real-time roll and pitch angles of the seat platform relative to the rear frame and is electrically connected to the cooperative controller. The satellite navigation GNSS is used to collect path look-ahead information and current vehicle speed, and to predict changes in road curvature and slope ahead.

[0014] Furthermore, step S5 includes the following sub-steps:

[0015] Step S5a: Based on the path look-ahead information provided by satellite navigation GNSS and the current vehicle speed, predict the slow-change disturbance of seat attitude caused by macro-terrain changes;

[0016] Step S5b: Based on the kinematic model and geometric mapping relationship of the folding and twisting waist, predict the rapid change perturbation of seat posture caused by the folding and twisting waist swing;

[0017] Step S5c: Combine the prediction results from steps S5a and S5b to generate a comprehensive feedforward compensation signal.

[0018] Step S5d: Perform vibration spectrum analysis on the vertical acceleration signal of the vehicle body using short-time Fourier transform, extract the dominant excitation frequency, and query the preset mapping table based on the dominant excitation frequency to calculate the optimal equivalent stiffness and damping parameters required by the seat system.

[0019] Step S5e: The integrated feedforward compensation signal, the deviation between the current posture and the target posture of the seat, and the optimal stiffness and damping parameters are fused together and solved by an adaptive PID controller based on model prediction to generate a coordinated control command that integrates position, stiffness and damping multi-objective commands.

[0020] Furthermore, in step S6, the drive module drives the seat's multi-degree-of-freedom adjustment mechanism to perform tilt and pitch adjustments, including: the tilt servo electric cylinder and the pitch servo electric cylinder precisely control the output torque and speed of the motor according to the coordinated control command, converting the rotational motion into linear motion, and driving the seat's tilt and pitch adjustment mechanism.

[0021] Furthermore, the method also includes: in step S7, during the roll and pitch adjustment process, the cooperative controller receives real-time status information such as steering and load from the vehicle's CAN bus. If special working conditions such as sharp turns or heavy-load operations are detected, the stiffness and damping weights in the control command are dynamically increased to prioritize support stability.

[0022] Furthermore, the method also includes: step S8, after the end of a single control cycle, returning to step S2, and performing data acquisition and cyclic control for the next cycle.

[0023] The beneficial effects of this invention are: (1) The driver's comfort is fundamentally improved. Through active leveling based on flexion and twisting waist movement prediction and GNSS terrain look-ahead, as well as adaptive stiffness and damping adjustment for human body sensitive frequency vibration, the system can actively and accurately maintain the stability of the driver's torso posture. It can reduce the effective value of human-machine weighted acceleration by more than 50% compared with traditional seats, significantly relieving muscle fatigue.

[0024] (2) The response speed and accuracy of the control system are significantly optimized. The IMU / GNSS multi-source fusion sensing and feedforward-feedback collaborative control strategy is adopted to overcome the lag of pure feedback control and realize the synchronous response of seat adjustment and vehicle movement, making the action faster and the process smoother.

[0025] (3) Enhance the overall operating efficiency and safety. The system can automatically switch control modes according to the vehicle's steering, load and other states. While ensuring comfort, it provides stable control support for the driver, reduces misoperation, and improves the passability and operational stability of complex terrain. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0027] Figure 1 This is a flowchart illustrating an active seat leveling method for a folding and twisting tractor according to the present invention.

[0028] Figure 2 This is a block diagram illustrating the control system principle of an active seat leveling method for a folding and twisting tractor according to the present invention.

[0029] Figure 3 This is a schematic diagram of the multi-degree-of-freedom adjustment mechanism for the seat in this invention.

[0030] In the diagram: 1-seat, 2-seat mounting platform, 3-ball joint mechanism, 4-tilt servo electric cylinder, 5-rear frame base, 6-pitch servo electric cylinder. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of protection.

[0032] Please see Figure 1 This invention discloses an active seat leveling system for a folding and twisting tractor, comprising an attitude sensing module, a control module, an execution module, and a drive module.

[0033] The attitude perception module includes a flexure / torsion joint sensor, front / rear frame inertial measurement units (IMUs), a seat attitude sensor, and GNSS (GNSS) satellite navigation. The flexure / torsion joint sensor is mounted on the tractor's flexure / torsion hinge shaft and outputs the real-time swing angle α(t) and angular velocity of the hinge point. The front and rear frame inertial measurement units (IMUs) are rigidly mounted on the front and rear frames of the tractor, respectively, to measure the vehicle's three-axis attitude angles, angular velocities, and accelerations. High-precision pose is obtained by fusing the data with GNSS data through Kalman filtering. The seat attitude sensor is fixed to the seat mounting platform base and measures the seat's roll angle Φ relative to the rear frame. 座 (t) and pitch angle Ψ 座 (t); Satellite navigation GNSS provides absolute position, velocity, and information on the curvature and slope of the path ahead.

[0034] The drive module is a high-power servo electric cylinder. The tilt and pitch servo electric cylinders convert rotational motion into linear motion, which in turn transmits the driving force to the execution module, namely the multi-degree-of-freedom seat adjustment mechanism, causing the seat's multi-degree-of-freedom adjustment structure to tilt or pitch. The resulting force and displacement signals can be fed back to the collaborative control module for further correction. The high-power servo electric cylinder operates in a three-loop closed-loop mode of torque, speed, and position. The torque loop is the inner loop, the speed loop is the middle loop, and the position loop is the outer loop. The parameters of the three loops are adaptively calibrated based on the vehicle's operating conditions.

[0035] The execution module is a multi-degree-of-freedom seat adjustment mechanism. The seat mounting platform is connected to the rear frame base via a ball joint mechanism. The two ends of the tilt servo electric cylinder are connected to the left side of the base and the left side of the platform, respectively; the two ends of the pitch servo electric cylinder are connected to the rear of the base and the rear of the platform, respectively. Through the coordinated extension and retraction of the two electric cylinders, the platform rotates around the pitch and tilt axes, completing the seat tilt and pitch adjustments. The control module receives real-time pose data from the attitude perception module and vehicle speed, steering, and load status information from the vehicle's CAN bus. This data is combined with terrain prediction based on GNSS satellite navigation and target attitude prediction based on seat mounting point attitude changes. The stiffness and damping calculation module then obtains multi-objective control commands for position, stiffness, and damping, which are transmitted to the drive module.

[0036] Please see Figure 2 The present invention also provides a method for actively leveling the seat of a folding and twisting tractor, comprising:

[0037] Step S1: Initialize the control system. Load the ideal working posture of the seat (0° tilt angle, 5° pitch angle) into the kinematic model parameters of the folding and twisting motion, such as the front frame length L1, rear frame length L2, compensation coefficient β, initial parameters of the PID controller Kp, Ki, Kd, ​​feedforward fusion weights w1, w2, w3, multi-objective optimization weights λ1, λ2, λ3, λ4, and the preset bump threshold R. th 15° / s, vehicle speed threshold v th The trigger thresholds are 8 km / h and for special operating conditions;

[0038] Step S2: Real-time data acquisition. Within each control cycle Tt, the attitude sensing module synchronously acquires: the swing angle α(t) and angular velocity of the folding-twist hinge point. Attitude angles, angular velocities, and accelerations output by the front and rear frame IMUs; Φ values ​​output by the seat attitude sensor. 座 (t) and Ψ 座 (t); The latitude, longitude, elevation, heading angle, vehicle speed v(k) and elevation sequence h(k+d) of the road ahead preview point output by GNSS;

[0039] Step S3: Control mode determination. The attitude perception module processes the collected data in real time and calculates the current road surface bumpiness R(k). For example, it takes the root mean square value of the vehicle's vertical acceleration. If R(k) > R th This indicates that the road surface is extremely rugged, and the prediction model may fail. Stability should be prioritized, or when v(k) <v th If the vehicle speed is too low, the dynamics change slowly, and the efficiency of complex control is low, then the simplified feedback control mode is entered, i.e., step S4 is executed; otherwise, the more comprehensive cooperative predictive control mode is entered, i.e., step S5 is executed, in order to pursue optimal comfort and stability.

[0040] Step S4: Simplify the feedback control mode. The co-controller calculates the required seat position adjustment command based solely on the deviation between the current seat posture and the target posture using PID control.

[0041]

[0042] Where u pos (k) represents the position adjustment command, where e(k) is the deviation between the current seat posture and the target posture. 目标 -Φ 座 (k), Ψ 目标 -Ψ 座 (k)]T, then proceed to step S6;

[0043] Step S5: The collaborative controller enters the feedforward-feedback collaborative predictive control mode and executes the following sub-steps in sequence:

[0044] Step S5a: Macro-terrain prediction. Based on the high-order sequence h(k+d) of GNSS pre-aiming and the vehicle dynamics model, predict the slow-varying perturbations in seat attitude caused by terrain:

[0045]

[0046] After discretization, θ is obtained 慢 (k+d), where G(s) is the vehicle pitch / roll dynamics transfer function, τ is the aiming delay time, and d is the aiming step number, which is calculated from the aiming distance and vehicle speed;

[0047] Step S5b: Predicting folding and twisting waist perturbations. This involves using the folding and twisting waist kinematic model and geometric mapping relationships to predict rapid changes in seat posture.

[0048]

[0049]

[0050] Where α(t) is the swing angle of the hinge point at time t. Let L1 and L2 be the angular velocity of the pivot joint, L1 and L2 be the geometric parameters of the front and rear frames, respectively, β be the compensation coefficient, and ΔΦ be the angular velocity of the pivot joint. 快 For the predicted rapidly varying pitch component, Δψ 快 For the predicted rapid component of the roll angle;

[0051] Step S5c: Feedforward signal fusion. The prediction results from steps S5a and S5b are weighted and fused to generate a comprehensive feedforward compensation signal.

[0052]

[0053] Where w1∈[0.2,0.8], it increases linearly with increasing vehicle speed; w2 and w3 ∈ [0.1, 0.4], and these weighting coefficients are adaptively adjusted according to the current speed of the tractor and the swing amplitude of the folding and twisting, and satisfy w1 + w2 + w3 = 1;

[0054] Step S5d: Stiffness and damping calculation. Perform a short-time Fourier transform on the vehicle body vertical acceleration signal to extract the dominant excitation frequency ω0. Based on the dominant excitation frequency, consult a preset mapping table to calculate the optimal equivalent stiffness and damping parameters required by the seat system. Consult a pre-calibrated "frequency-optimal impedance" mapping table.

[0055]

[0056] The "frequency-optimal impedance" mapping table is pre-calibrated based on the principle of optimal vibration isolation performance of the seat system under different excitation frequencies, ensuring that the vibration isolation performance of the seat is optimal under different frequencies.

[0057] Step S5e: Generation of multi-objective cooperative control commands to integrate feedforward compensation u ff (k), the deviation e(k) between the current posture and the target posture of the seat, and the optimal stiffness damping (K0,C0) are taken as inputs. The multi-objective collaborative solution is achieved by constructing a multi-objective optimization function that includes minimizing the seat posture tracking error, minimizing the system energy consumption, and optimizing the support stiffness.

[0058]

[0059] Where e(k) is the deviation between the current seat posture and the target posture, u fb (k) represents the feedback control quantity, generated by a PID or fuzzy controller; λ1~λ4 are the dynamic weights; K(k) and C(k) are the current stiffness and damping, respectively; and K0 and C0 are the optimal stiffness and damping, respectively. Solving for this value yields the position adjustment command u. pos =u ff +u fb Stiffness adjustment command u K = K (k), damping adjustment command u C =C(k), forming a cooperative control command vector U(k)=[ u pos , u K , u C ]T;

[0060] Step S6: Instruction execution, the cooperative controller sends the position adjustment instruction generated in step S4 or the cooperative control instruction generated in step S5e to the drive module, and executes the stiffness adjustment instruction u. K The motor torque loop stiffness is adjusted by controlling the current loop gain, according to the damping adjustment command u. C The speed loop damping is adjusted by the speed feedback coefficient to drive the electric cylinder to extend and retract, so that the seat platform moves according to the target posture.

[0061] Step S7: Adaptive adjustment of operating conditions. During the adjustment process, the cooperative controller receives the steering angle δ(t) and traction load F from the vehicle's CAN bus in real time. L (t). If a sharp turn is detected, i.e., |δ(t)|>δ th And the steering angular velocity exceeds the threshold or heavy load operation, i.e., F L (t)> F th This dynamically increases the stiffness and damping weights in multi-objective optimization:

[0062]

[0063] The co-controller prioritizes increasing the seat support stiffness and damping to ensure the driver receives stable support under severe tilting or heavy load; once the special operating conditions end, the weights return to their original values.

[0064] Step S8: Loop Control. After all instructions for the current control cycle have been issued and executed, the program returns to step S2 to begin data acquisition, judgment, and control for the next control cycle. This forms a real-time closed-loop control of perception-decision-execution-feedback, enabling the seat system to continuously and dynamically adapt to the ever-changing driving and working environment.

[0065] The structural diagram of the multi-degree-of-freedom adjustment mechanism for the seat is as follows: Figure 3As shown in the diagram, this invention provides a multi-degree-of-freedom seat adjustment mechanism, including a seat 1, a seat mounting platform 2, a ball joint mechanism 3, a tilt servo electric cylinder 4, a rear frame base 5, and a pitch servo electric cylinder 6. The seat 1 is fixedly mounted on the upper surface of the seat mounting platform 2. The seat mounting platform 2 is connected to the rear frame base 5 via the ball joint mechanism 3, allowing the seat mounting platform 2 to rotate relative to the rear frame base 5 around the pitch axis (vehicle lateral) and the tilt axis (vehicle forward direction). The rear frame base 5 is fixedly mounted on the tractor's rear frame. The motor housing end of the tilt servo electric cylinder 4 is fixed to the left side of the rear frame base 5, and its push rod end is hinged to the corresponding side of the seat mounting platform 2 via a hinged support. The tilt adjustment is achieved by driving the seat mounting platform 2 to rotate around the tilt axis through the extension and retraction of the tilt servo electric cylinder 4. The motor housing of the pitch servo electric cylinder 6 is fixed to the rear of the rear frame base 5, and its push rod end is hinged to the rear of the seat mounting platform 2 via a hinged support. The pitch adjustment is achieved by driving the seat mounting platform 2 to rotate around the pitch axis through the extension and retraction of the pitch servo electric cylinder 6. The tilt servo electric cylinder 4 works in conjunction with the pitch servo electric cylinder 6, and can precisely adjust the tilt and pitch angles of the seat 1 according to the instructions of the co-controller, so that the seat always remains horizontal or at a preset comfortable angle.

[0066] The present invention has the following beneficial effects: (1) The driver's comfort is fundamentally improved. Through active leveling based on flexion and twisting waist movement prediction and GNSS terrain look-ahead, as well as adaptive stiffness and damping adjustment for human body sensitive frequency vibration, the system can actively and accurately maintain the stability of the driver's torso posture. It can reduce the effective value of human-machine weighted acceleration by more than 50% compared with traditional seats, and significantly alleviate muscle fatigue.

[0067] (2) The response speed and accuracy of the control system are significantly optimized. The IMU / GNSS multi-source fusion sensing and feedforward-feedback collaborative control strategy is adopted to overcome the lag of pure feedback control and realize the synchronous response of seat adjustment and vehicle movement, making the action faster and the process smoother.

[0068] (3) Enhance the overall operating efficiency and safety. The system can automatically switch control modes according to the vehicle's steering, load and other states. While ensuring comfort, it provides stable control support for the driver, reduces misoperation, and improves the passability and operational stability of complex terrain.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort, such as modifications to the technical solutions described in the following embodiments or equivalent substitutions of some technical features, are within the scope of protection of the present invention.

Claims

1. A method for actively leveling the seat of a folding and twisting tractor, characterized in that, include: Step S1: Initialize the control system; Step S2: The attitude perception module collects pose parameters and path information in real time, including the swing angle and angular velocity of the hinge point, the inertial measurement data of the front and rear frames and seats, and the satellite navigation GNSS positioning data. Step S3: The cooperative controller calculates the current road surface bump level and vehicle speed based on the pose parameters and path information collected by the attitude control module in step S2. If the current road surface bump level is greater than the preset bump threshold or the current vehicle speed is lower than the preset vehicle speed threshold, then proceed to step S4; otherwise, proceed to step S5. Step S4: The collaborative controller generates a seat position adjustment command based solely on the deviation between the current seat posture and the target posture collected by the posture perception module using a PID feedback control algorithm, and then executes step S6. Step S5: The cooperative controller enters the feedforward-feedback cooperative predictive control mode and generates cooperative control commands; Step S6: The collaborative controller sends the position adjustment command generated in step S4 or the collaborative control command generated in step S5 to the drive module, driving the multi-degree-of-freedom adjustment mechanism of the seat to perform tilt and pitch adjustments.

2. The method for actively leveling the seat of a folding and twisting tractor according to claim 1, characterized in that, Step S1 initializes the control system by setting the target posture angle of the seat, predictive control parameters, and various thresholds.

3. The method for actively leveling the seat of a folding and twisting tractor according to claim 1, characterized in that, In step S2, the attitude perception module includes a folding and twisting joint sensor, a vehicle body inertial measurement unit (IMU), a seat attitude sensor, and a satellite navigation GNSS. The folding and twisting joint sensor is installed on the tractor's folding and twisting hinge shaft and is used to measure the swing angle and angular velocity of the folding and twisting in real time. Two inertial measurement units (IMUs) are rigidly mounted on the front and rear frames of the tractor to measure the vehicle's attitude, angular velocity, and acceleration, and are fused with GNSS data using a Kalman filter algorithm. A seat attitude sensor is mounted on an adjustment platform base under the seat cushion to measure the deviation between the seat's current attitude and the target attitude. GNSS satellite navigation is used to collect forward-looking information about the route and the current vehicle speed, and to predict changes in the curvature and slope of the road ahead.

4. The method for actively leveling the seat of a folding and twisting tractor according to claim 1, characterized in that, Step S5 includes the following sub-steps: Step S5a: Based on the path look-ahead information provided by satellite navigation GNSS and the current vehicle speed, predict the slow-change disturbance of seat attitude caused by macro-terrain changes; Step S5b: Based on the kinematic model and geometric mapping relationship of the folding and twisting waist, predict the rapid change perturbation of seat posture caused by the folding and twisting waist swing; Step S5c: Combine the prediction results from steps S5a and S5b to generate a comprehensive feedforward compensation signal. Step S5d: Perform vibration spectrum analysis on the vertical acceleration signal of the vehicle body using short-time Fourier transform, extract the dominant excitation frequency, and query the preset mapping table based on the dominant excitation frequency to calculate the optimal equivalent stiffness and damping parameters required by the seat system. Step S5e: The integrated feedforward compensation signal, the deviation between the current posture and the target posture of the seat, and the optimal stiffness and damping parameters are fused together and solved by an adaptive PID controller based on the kinematic model of bending, twisting and turning to generate a coordinated control command that integrates position, stiffness and damping multi-objective commands.

5. The method for actively leveling the seat of a folding and twisting tractor according to claim 1, characterized in that, In step S6, the drive module drives the seat's multi-degree-of-freedom adjustment mechanism to perform tilt and pitch adjustments. This includes: the tilt servo electric cylinder and the pitch servo electric cylinder precisely control the output torque and speed of the motor according to the coordinated control command, converting the rotational motion into linear motion, and driving the seat's tilt and pitch adjustment mechanism.

6. The method for actively leveling the seat of a folding and twisting tractor according to claim 1, characterized in that, The method further includes: in step S7, during the roll and pitch adjustment process, the cooperative controller receives status information from the vehicle's CAN bus in real time. If a special working condition is detected, the stiffness and damping weights in the cooperative control command are dynamically increased.

7. The method for actively leveling the seat of a folding and twisting tractor according to claim 1, characterized in that, The method further includes: step S8, after the end of a single control cycle, returning to step S2, and performing data acquisition and cyclic control for the next cycle.

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