Anti-rollover control method and system suitable for manual and automatic driving tractors

Abstract

The invention provides an anti-rollover control method and system suitable for a manual and automatic driving tractor, and the method employs front wheel steering and moment gyroscope combined control, and predicts a rollover risk based on a tractor rollover risk evaluation index and a moment gyroscope control margin according to the real-time states of the tractor and a moment gyroscope; anti-rollover control of front wheel steering and moment gyroscope combination is realized in a high rollover risk state; in a low rollover risk state, self-adaptive coordination control of rollover prevention and path tracking is realized in an automatic driving mode, and self-adaptive coordination control of rollover prevention and driving comfort is realized in a manual driving mode. The system comprises a state acquisition subsystem, a steering subsystem, a moment gyroscope subsystem and an anti-rollover controller, and the anti-rollover controller fuses data information of the state acquisition subsystem and automatically selects anti-rollover control strategies in different driving modes. And multi-target self-adaptive control leading to rollover prevention is realized through the moment gyroscope subsystem and the steering subsystem.

Description

Technical Field

[0001] The present invention belongs to the technical field of active safety of tractors. Specifically, it relates to a rollover prevention control method and system applicable to manual and autonomous tractors. Background Art

[0002] Tractors operating in hilly and mountainous areas have poor driving stability. Especially when operating on slopes, they are extremely prone to rollover. Accident analyses of agricultural machinery in many countries show that nearly half of the casualty accidents are related to tractor rollovers. Tractor rollovers have become a major safety hazard in the agricultural production process. The complex mountain environment and improper driving operations increase the probability of tractor rollovers.

[0003] In response to the frequent rollover problems during tractor operations, the developed and promoted rollover protection devices have reduced the casualty rate of rollover accidents. However, they can only provide a relatively safe escape space for the driver and reduce damage to the vehicle, but they themselves cannot prevent tractor rollovers. The rollover warning system can, according to the rollover risk level of the tractor, send a prompt to the operator when the tractor reaches the critical rollover state. It is one of the effective solutions to reduce or avoid rollover risks. According to investigations, even if a rollover warning system is installed on a tractor, nearly half of the rollover accidents cannot be avoided solely by the driver's operation. This is because the time for a rollover to occur is very short. Even an experienced driver can hardly detect the warning signal in a very short time and make the correct rollover prevention operation in time. Moreover, in some working conditions, relying solely on the driver's operation is not sufficient to prevent tractor rollovers. The active rollover prevention system can accurately and quickly activate the rollover prevention function according to the state of the tractor. Therefore, the intervention of the rollover prevention system can further reduce the probability of tractor rollovers.

[0004] At present, there are many studies on the active anti-rollover technology of tractors at home and abroad. For example, the invention patent with the application number 201910409550.1 discloses an active anti-rollover control method and system for a wheeled tractor based on active steering control. By collecting the lateral roll instability state signal of the tractor, the rollover trend of the tractor is judged, and the stability control of the tractor is realized through the front-wheel steering. The invention patent with the application number 202010736931.3 discloses a tractor anti-rollover control system and its control method, which divides the rollover degree of the tractor into levels and formulates corresponding early warning and active anti-rollover control measures. The invention patent with the application number 202110717603.3 discloses a tractor extreme state stability recovery and operation state compensation gyro active control system and method, and designs a tractor extreme state stability recovery control system according to the principle that the precession of a high-speed gyro rotor generates a counter torque for the tractor to recover stability. In addition, tractors with attitude adjustment proposed in invention patents with the application numbers 202310053336.3, 202311270302.6, and 202410312325.7 have good vehicle body stability functions during slope operation.

[0005] It can be seen from the above technical literature and by consulting relevant design materials that the existing technologies have the following problems: 1. Tractors are different from road vehicles. Their rollovers occur suddenly and rapidly, which requires high response capabilities and anti-rollover torques that can be provided by the active anti-rollover control system. The existing tractor anti-rollover control mainly uses a single anti-rollover actuator, and the anti-rollover torque that can be provided is limited.

[0006] 2. Due to the strong coupling between the tractor and the anti-rollover actuator, currently, for the state monitoring and anti-rollover control of tractors, only the tractor rollover risk assessment index is relied on to estimate the tractor rollover risk, lacking the dynamic definition of the effective anti-roll torque of the anti-rollover actuator. Therefore, the timeliness of the anti-roll torque is reduced, restricting the stability recovery effect of the active anti-rollover control.

[0007] 3. The performance requirements of tractors in different driving modes pose new challenges to the tractor stability control process, such as the driving comfort requirements in the manual driving mode and the path tracking accuracy requirements in the automatic driving mode. The existing anti-rollover control methods do not take into account the multi-objective control requirements of path tracking accuracy and driving comfort, and problems such as a decline in operation quality or driver discomfort will occur during the anti-rollover control process. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide an anti-rollover control method and system applicable to manual and autonomous tractors. The method and system of the present invention enhance the anti-rollover ability of the tractor under different working conditions by selecting an appropriate combination of anti-rollover actuators; provide a rollover risk assessment method applicable to active anti-rollover control, establish an internal connection between the rollover risk of the tractor and the control margin of the anti-rollover actuator, and enhance the timeliness and rapidity of anti-rollover control; and can meet the performance requirements under different driving modes on the basis of achieving lateral stability according to the rollover risk level of the tractor.

[0009] To solve the above technical problems, the present invention adopts the following technical means: An anti-rollover control method applicable to manual and autonomous tractors, the anti-rollover control method adopts a combined control mode of front-wheel steering and torque gyroscope, and can predict the rollover risk based on the real-time states of the tractor and the torque gyroscope, based on the rollover risk assessment index of the tractor and the control margin of the torque gyroscope; realize the anti-rollover control combining front-wheel steering and torque gyroscope under the high rollover risk state; under the low rollover risk state, realize the adaptive coordination control of anti-rollover and path tracking accuracy in the autonomous driving mode, and realize the adaptive coordination control of anti-rollover and driving comfort in the manual driving mode.

[0010] The advantages of the present invention are as follows: 1. Design a combined anti-rollover actuator with the torque gyroscope as the leading factor and front-wheel steering as the auxiliary. Through the combined action of multiple anti-rollover actuators, not only the anti-roll torque of the anti-rollover system under the high rollover risk state is enhanced, but also a control basis for the control requirements under different driving modes is provided under the low rollover risk state.

[0011] 2. Use the comparison value between the roll torque of the tractor and the anti-roll torque margin of the torque gyroscope as a supplement to the rollover risk assessment index to determine the intervention timing of anti-rollover control, which can significantly improve the rapid response ability of the anti-rollover system under normal rollover conditions. In addition, the control strategy formulated based on this comparison value is conducive to the dynamic adjustment of the control target during the anti-rollover process and can also enhance the rollback ability of the anti-rollover system under special conditions.

[0012] 3. The rollover prevention system has the function of automatically identifying the driving mode of the tractor and can achieve multi-objective adaptive control with rollover prevention as the leading factor according to the rollover risk: in the manual driving mode, while realizing the rollover prevention function, the system can comprehensively consider the driver's driving intention and riding comfort. In the automatic driving mode, the system can take into account the path tracking accuracy requirements and reduce or avoid the impact on the operation quality. This technical solution realizes the target adaptive control with rollover prevention as the leading factor from two aspects of the intervention timing and intervention method of rollover prevention control, and can automatically adjust the control strategy according to different rollover risk levels and driving modes of the tractor, improving the comprehensive performance of the tractor.

[0013] The rollover prevention control method applicable to manual and automatic driving tractors is characterized by including the following steps: S1: Collect and process the state parameters related to the tractor, front wheel steering angle and torque gyroscope, including the operating speed of the tractor , roll angle , lateral acceleration , suspension hydraulic cylinder pressure , steering column torque , steering wheel angle , torque gyroscope base motor angle , torque gyroscope rotor motor speed ; S2: Estimate the total mass of the tractor according to the suspension hydraulic cylinder pressure . For a tractor operating in complex terrain, the total mass is an important factor affecting its lateral stability; S3: Estimate the height of the tractor's center of mass according to the roll angle of the tractor and the estimated total mass of the tractor ; The position of the center of gravity is a very important factor affecting the rollover of the tractor, especially for tractors operating on slopes, and the impact is greater. Moreover, the change of the load will directly affect the position of the vehicle's center of gravity. For example, when the tractor is used for fruit harvesting and seeding and fertilizing, its load is constantly changing. Since it is difficult to measure the height and position of the center of gravity, the influence of the tractor's center of gravity on stability is ignored in the existing rollover prevention technologies. The present invention estimates the height of the tractor's center of mass according to the roll angle and total mass of the tractor, and can more accurately predict the rollover risk of the tractor.

[0014] S4: Calculate the rollover risk evaluation index of the tractor ; S5: Judge the rollover risk level of the tractor according to the rollover risk evaluation index of the tractor : If ​​, if the rollover risk is high, anti-rollover control combining front-wheel steering and a moment gyro is implemented, and step S6 is executed; if , if the rollover risk is low, the roll torque value of the tractor and the anti-roll torque margin of the moment gyro need to be calculated and compared as a supplement to the tractor rollover risk evaluation index for further judging the rollover risk, and control is carried out according to the high or low risk level judged; S6: Establish the combined anti-rollover control constraint condition 1, that is, the maximum steering angle of the tractor, the maximum rotation angle of the moment gyro base, and the maximum speed of the moment gyro rotor are constrained, which are used as the basic conditions for stable control aiming at anti-rollover; S7: For different rollover risk levels and different driving modes, the provided control method has different control strategies, and each control strategy allocates the front-wheel steering angle and the output torque value of the moment gyro by the corresponding LQR controller; in the state of high rollover risk, based on the constraint condition 1 established in S6, the combined anti-rollover control strategy uses the LQR controller 1 to allocate the front-wheel steering angle and the output torque value of the moment gyro; For different rollover risk levels and different driving modes, the provided control method has three control strategies, and each control strategy designs specific constraint conditions and designs corresponding LQR controllers based on the LQR theory, namely LQR controller 1, LQR controller 2, and LQR controller 3. The corresponding LQR controller is selected under different rollover risk levels and different driving modes to allocate the front-wheel steering angle and the output torque value of the moment gyro; S8: Use the front-wheel steering angle allocated by the LQR controller as the expected value, and achieve rapid tracking of the expected front-wheel steering angle through closed-loop control; S9: Use the output torque of the moment gyro allocated by the LQR controller as the expected value, and perform closed-loop control on the rotation angle of the moment gyro base and the rotor speed respectively to achieve rapid tracking of the expected output torque of the moment gyro.

[0015] The anti-rollover control method applicable to manual and autonomous tractors is characterized in that in step S5, in the state of low rollover risk, the roll torque value of the tractor and the anti-roll torque margin of the moment gyro need to be calculated and compared as a supplement to the tractor rollover risk evaluation index for further judging the rollover risk, and specifically includes the following steps: S10: Calculate the roll torque of the tractor , as one of the parameters for judging the rollover degree and the intervention of anti-rollover control; due to the suddenness of tractor rollover, sufficient anti-roll torque is required to maintain its balance. In special rollover working conditions, the situation of insufficient anti-roll torque may occur, or even if the tractor rollover risk evaluation index is relatively low, but the controllable anti-roll torque margin of the moment gyro is equivalent to the tractor rollover torque value. At this time, there is a certain risk in the tractor's return-to-stability control; to improve the timeliness of anti-rollover control, the comparison value between the tractor rollover torque value and the anti-roll torque margin of the moment gyro is used as the reference basis for the intervention timing of anti-rollover control; S11: Calculate the anti-roll torque margin of the moment gyro ; S12: Compare the tractor rollover torque and the anti-roll torque margin of the moment gyro , if , the tractor has no rollover risk and no anti-rollover control intervention is required, then return to S1; if , the tractor is in a low-risk rollover state but anti-rollover control intervention is required, then execute S13; S13: If , the tractor rollover risk is high, then implement the anti-rollover control combining front-wheel steering and the moment gyro, and execute S6; if , the tractor rollover risk is low, then implement the corresponding control strategy according to the driving mode. Through the above scheme, it is possible to realize the anti-rollover control strategy with the moment gyro as the leading and front-wheel steering as the auxiliary according to the lateral stability of the tractor and the state of the moment gyro. In the process of anti-rollover control, not only the rollover degree of the tractor is fully considered, but also the definition of the effective anti-roll ability of the anti-rollover actuator is introduced, which can significantly improve the return-to-stability probability of the tractor in the critical rollover state and can enhance the fast response ability of the return-to-stability control.

[0016] In the step S13 described above, when the tractor rollover risk is low, the corresponding control strategy is implemented according to the driving mode, and the control is carried out according to the judgment of high or low risk level; it includes the following steps: S14: When the tractor is in a low-risk rollover state, the control method automatically judges the driving mode and realizes the adaptive coordinated control of the operation quality or driving experience. First, process the torque signal of the tractor steering column to determine the torque magnitude and direction; S15: Judge whether the current mode of the tractor is autonomous driving or manual driving; S16: If the tractor is in the autonomous driving mode, then establish the constraint condition 2 under the low rollover risk and autonomous driving mode; that is, according to the tractor operation speed and the lateral acceleration set the maximum change amount of the front-wheel steering angle within the path tracking error range ; S17: Based on the constraint condition 2 in the automatic driving mode established in S16, use the LQR controller 2 to allocate the front wheel steering angle and the torque gyro output torque that prioritize anti-rollover and take into account the path tracking accuracy, and then execute S8 and S9; S18: If the tractor is in the manual driving mode, establish the constraint condition 3 in the low rollover risk and manual driving mode; that is, according to the steering column torque , steering wheel angle and angular velocity to identify the driver's intention and establish the front wheel steering range that meets driving comfort and driving intention ; S19: Based on the constraint condition 3 in the manual driving mode established in S18, use the LQR controller 3 to allocate the front wheel steering angle and the torque gyro output torque that prioritize anti-rollover and take into account driving intention and comfort, and then execute S8 and S9.

[0017] The step S4 described above: Calculate the rollover risk evaluation index of the tractor , and the calculation of this index is based on the roll angle of the tractor and the estimated value of the center of mass height , that is .

[0018] The step S10 described above: Calculate the roll torque of the tractor , introduce the operating speed of the tractor, roll angle , lateral acceleration , total tractor mass and center of mass height parameters to obtain the roll torque of the tractor.

[0019] The step S11 described above, calculate the anti-roll torque margin of the torque gyro , comprehensively consider the roll angle of the tractor, roll torque , the angle of the torque gyro base motor and the rotational speed value of the torque gyro rotor motor to calculate the anti-roll torque of the torque gyro.

[0020] Through the above scheme, the corresponding control constraints of the tractor in the automatic driving mode and the manual driving mode are constructed, that is, the two key performance indicators of path tracking accuracy and driving comfort, and they are used as one of the conditions for multi-objective adaptive control with anti-rollover as the main goal, which not only ensures that the tractor can achieve anti-rollover control in different driving modes, but also takes into account the performance requirements such as path tracking accuracy and driving comfort, thus realizing the optimization and improvement of the comprehensive performance of the tractor.

[0021] The anti-rollover system applicable to manual and autonomous tractors includes a state acquisition subsystem, a steering subsystem, a torque gyroscope subsystem, and an anti-rollover controller.

[0022] The state acquisition subsystem is responsible for monitoring the state parameters of the tractor. The state acquisition subsystem is electrically connected to the anti-rollover controller and transmits the state parameters to the anti-rollover controller. In this technical solution, the state acquisition subsystem senses the state of the tractor and sends relevant data to the anti-rollover controller. The anti-rollover controller judges the driving mode and the degree of rollover risk of the tractor, and through the combined action of the steering subsystem and the torque gyroscope subsystem, realizes anti-rollover control dominated by anti-rollover and taking into account the requirements of different driving modes.

[0023] The anti-rollover controller uses a 32-bit microprocessor STM32F103 as the control core.

[0024] The steering subsystem includes a power steering motor assembly, a steering column, and a hydraulic steering unit. The power steering motor assembly is installed on the steering column. The steering column connects the steering wheel and the hydraulic steering unit. The power steering motor assembly is electrically connected to the anti-rollover controller.

[0025] The torque gyroscope subsystem is installed on the upper part of the front chassis of the tractor. The torque gyroscope subsystem includes a base motor and a rotor motor, and is electrically connected to the anti-rollover controller.

[0026] Through the above solution, the controllable anti-roll torque of the tractor can be improved, and complex modification of the tractor chassis is avoided, improving the cost performance of the anti-rollover system.

[0027] The anti-rollover controller integrates the data information of the state acquisition subsystem, automatically selects the anti-rollover control strategy under different driving modes, and realizes multi-objective adaptive control dominated by anti-rollover through the torque gyroscope subsystem and the steering subsystem.

[0028] The anti-rollover system applicable to manual and autonomous tractors is characterized in that: the state acquisition subsystem is provided with a Hall speed sensor, a pose sensor, a pressure sensor, a steering column torque and angle sensor, a magnetic encoder and an optical encoder, which can monitor the state parameters of the tractor and the anti-rollover actuator in real time, and can collect the operating speed of the tractor , roll angle , lateral acceleration , suspension hydraulic cylinder pressure steering column torque , steering wheel angle , base motor angle , rotor motor speed parameter values.

[0029] The Hall speed sensor selects VB-Z9400 and is installed near the rear axle of the tractor for detecting the operating speed of the tractor.

[0030] The pose sensor selects the six-axis gyroscope JY61 module for detecting the roll angle and lateral acceleration of the tractor.

[0031] The pressure sensor selects the Rexroth pressure sensor HM20 for detecting the pressure of the suspension hydraulic cylinder.

[0032] The steering column torque and rotation angle sensor selects the Hella non-contact rotation angle torque sensor for detecting the torque and rotation angle of the steering column and converting them into the steering wheel rotation angle.

[0033] The rotation angle of the motor selects the AS5600 magnetic encoder module for detecting the rotation angle of the torque gyro base.

[0034] The motor speed selects the HKT30301 optical encoder for detecting the rotor speed of the torque gyro.

[0035] The beneficial effects of the technical solution of the present invention: 1. Design a combined rollover prevention actuator with the torque gyro as the leading and front-wheel steering as the auxiliary. Through the combined action of multiple rollover prevention actuators, it not only enhances the roll resistance torque of the rollover prevention system in the high rollover risk state, but also provides a control basis for the control requirements in different driving modes in the low rollover risk state.

[0036] 2. Use the comparison value between the roll torque of the tractor and the roll resistance torque margin of the torque gyro as a supplement to the rollover risk evaluation index to determine the intervention timing of rollover prevention control, which can significantly improve the rapid response ability of the rollover prevention system in the conventional rollover condition. In addition, the control strategy formulated based on this comparison value is conducive to the dynamic adjustment of the control target during the rollover prevention process and can also enhance the rollback ability of the rollover prevention system in special conditions.

[0037] 3. The rollover prevention system has the function of automatically identifying the driving mode of the tractor and can achieve multi-objective adaptive control with rollover prevention as the leading according to the rollover risk: in the manual driving mode, the system can comprehensively consider the driver's driving intention and riding comfort while realizing the rollover prevention function. In the automatic driving mode, the system can take into account the path tracking accuracy requirements and reduce or avoid the impact on the operation quality.

[0038] 4. By monitoring the pressure of the suspension hydraulic cylinder, the mass and the height of the center of mass of the tractor can be effectively estimated, improving the accuracy of the rollover risk prediction of the tractor. Description of the Drawings

[0039] Figure 1Schematic diagram of the anti-rollover control method proposed by the present invention.

[0040] Figure 2 Flow chart of the anti-rollover control method proposed by the present invention.

[0041] Figure 3 Principle block diagram of the anti-rollover system proposed by the present invention.

[0042] Explanation of reference numerals: 1 - anti-rollover controller; 2 - steering subsystem; 3 - torque gyro subsystem; 4 - state acquisition subsystem. Detailed implementation manners

[0043] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The present invention covers any alternatives, modifications, equivalent methods and solutions made within the essence and scope of the present invention defined by the claims. In order to enable the public to have a better understanding of the present invention, in the detailed description of the present invention in the specific implementation manners, some specific details are described in detail, and for the parts not described, they are all conventional techniques in the art.

[0044] The embodiment of the present invention provides an anti-rollover control method and system applicable to manual and autonomous tractors, referring to Figures 1 - 3 . The anti-rollover control method for tractors, see Figure 1 and Figure 2 . Figure 1 As shown in the schematic diagram of the anti-rollover control method, it mainly involves three parts: the risk assessment of tractor rollover, the intervention timing and method of anti-rollover control, and the implementation of underlying control.

[0045] An anti-rollover control method applicable to manual and autonomous tractors adopts a combined control method of front-wheel steering and torque gyro, and can predict the rollover risk based on the real-time states of the tractor and the torque gyro, and based on the tractor rollover risk assessment index and the control margin of the torque gyro; in the state of high rollover risk, the anti-rollover control combining front-wheel steering and torque gyro is realized; in the state of low rollover risk, in the autonomous driving mode, the adaptive coordination control of anti-rollover and path tracking is realized, and in the manual driving mode, the adaptive coordination control of anti-rollover and driving comfort is realized.

[0046] The anti-rollover control method applicable to manual and autonomous tractors includes the following steps: S1: Collect and process the state parameters related to the tractor, front-wheel steering angle and torque gyro, including the operating speed of the tractor , roll angle , lateral acceleration , suspension hydraulic cylinder pressure 、Steering column torque 、Steering wheel angle 、Moment gyro base motor angle 、Moment gyro rotor motor speed ; S2: Estimate the total mass of the tractor according to the suspension hydraulic cylinder pressure , For tractors operating in complex terrains, the total mass is an important factor affecting their lateral stability; S3: Estimate the height of the tractor's center of mass according to the tractor's roll angle and the estimated total mass of the tractor , By introducing the change in the height of the center of mass of the tractor under different working conditions, the accuracy of rollover risk estimation is improved.

[0047] S4: Calculate the tractor rollover evaluation index ; S5: Judge the tractor rollover risk level according to the tractor rollover risk evaluation index : If , the rollover risk is high, then implement the rollover prevention control combining front-wheel steering and moment gyro, and execute S6; If , the rollover risk is low, it is necessary to calculate and compare the tractor roll torque value and the moment gyro anti-roll torque margin, as a supplement to the tractor rollover risk evaluation index, for further judging the rollover risk, and control according to the judged high or low risk level; S6: Establish the combined rollover prevention control constraint condition 1, that is, the maximum steering angle of the tractor, the maximum rotation angle of the moment gyro base, and the maximum speed of the moment gyro rotor are constrained, as the basic conditions for stability control with rollover prevention as the goal; S7: For different rollover risk levels and different driving modes, the provided control method has different control strategies, and each control strategy allocates the front-wheel steering angle and the moment gyro output torque value by the corresponding LQR controller; In the high rollover risk state, based on the constraint condition 1 established in S6, the combined rollover prevention control strategy uses the LQR controller 1 to allocate the front-wheel steering angle and the moment gyro output torque value; S8: Use the front-wheel steering angle allocated by the LQR controller as the expected value, and achieve fast tracking of the expected front-wheel steering angle through closed-loop control. The specific implementation steps are as follows: S8-1: Use the front-wheel steering angle obtained by the LQR controller as the expected value of the steering system; S8-2: Collect the steering wheel angle sensor value and convert it into the front-wheel steering angle data; ​​S8-3: Compare the actual front wheel angle with the desired front wheel angle value. If they are inconsistent, execute S8-4; otherwise, go to S9. S8-4: Change the front wheel angle by changing the PWM output 1 and go to S8-2. S9: Use the torque gyro output torque allocated by the LQR controller as the desired value, and perform closed-loop control on the torque gyro base angle and rotor speed respectively to achieve fast tracking of the desired output torque of the torque gyro. The specific implementation steps are as follows: S9-1: Use the torque gyro output torque allocated by the LQR as the desired output torque of the torque gyro subsystem. S9-2: Determine the desired torque gyro base angle according to the tractor roll angle and the desired output torque in S9-1. S9-3: Collect the base angle value through the angle sensor. S9-4: Compare the actual base angle with the desired base angle value. If they are inconsistent, execute S9-5; otherwise, go to S9-6. S9-5: Adjust the torque gyro base angle by changing the PWM output 2 and go to S9-3. S9-6: Determine the desired speed value of the torque gyro rotor according to the torque gyro base angle and the desired output torque in S9-1. S9-7: Collect the torque gyro rotor speed signal through the speed sensor. S9-8: Compare the actual speed of the torque gyro rotor with the desired speed. If they are inconsistent, execute S9-9; otherwise, go to S1. S9-9: Adjust the torque gyro rotor speed by changing the PWM output 3 and go to S9-7. Since the rollover of a tractor is sudden and maintaining its balance requires sufficient anti-roll torque, however, in special rollover conditions, there may be a situation of insufficient anti-roll torque; or even if the tractor rollover risk assessment index is low, but when the controllable anti-roll torque margin of the torque gyro is equivalent to the tractor roll torque, there is a certain risk in the tractor's rollback control at this time. To improve the timeliness of anti-rollover control, the comparison value between the tractor roll torque value and the anti-roll torque margin of the torque gyro is used as a reference for the intervention timing of anti-rollover control. Therefore, design step S5: In the low rollover risk state, it is necessary to calculate and compare the tractor roll torque value and the anti-roll torque margin of the torque gyro, as a supplement to the tractor rollover risk assessment index, for further judging the rollover risk, which specifically includes the following steps: S10: Calculate the tractor roll torque as a parameter for judging the rollover degree and the intervention of anti-rollover control. S11: Calculate the moment gyro anti-roll torque margin ; S12: Comparing tractor roll torque and moment gyro anti-roll torque margin ,if , the tractor has no risk of rollover and no rollover prevention control intervention is required, then the process returns to S1; if , if the tractor is in a low-risk rollover state but requires rollover prevention control intervention, execute S13; S13: If , the risk of the tractor rolling over is high, the anti-rollover control combined with the front wheel steering and the torque gyro is implemented, and S6 is executed; if , the risk of the tractor rolling over is low, and the corresponding control strategy is implemented according to the driving mode.

[0048] In the low rollover risk state, in step S13, a corresponding control strategy is implemented according to the driving mode, and control is performed according to the high or low risk level determined; the steps include: S14: When the tractor is in a low-risk rollover state, the control method automatically determines the driving mode and implements adaptive coordinated control of the work quality or driving experience. First, the torque signal of the tractor steering column is processed to determine the torque magnitude and direction; S15: determining whether the current mode of the tractor is automatic driving or manual driving; S16: If the tractor is in the automatic driving mode, then establish constraint condition 2 in the automatic driving mode with low rollover risk; i.e., according to the tractor operating speed and lateral acceleration Set the maximum change in the front wheel angle within the path tracking error range ; S17: Based on the constraint condition 2 in the automatic driving mode established in S16, the LQR controller 2 is used to allocate the front wheel steering angle and the torque output torque of the moment gyro with the rollover prevention as the main factor and the path tracking accuracy as the consideration, and then S8 and S9 are executed; S18: If the tractor is in manual driving mode, then establish constraint 3 in low rollover risk, manual driving mode; that is, according to the steering column torque , steering wheel angle and angular velocity Identify driver intentions and establish a front wheel steering range that meets driving comfort and driving intentions ; S19: Based on the constraint condition 3 in the manual driving mode established in S18, the LQR controller 3 is used to allocate the front wheel steering angle and the torque gyro output torque that are dominated by rollover prevention and take driving intention and comfort into consideration, and then S8 and S9 are executed.

[0049] Anti-rollover control method applicable to manual and autonomous tractors. For step S4: Calculate the rollover risk assessment index of the tractor , the calculation of this index is based on the roll angle of the tractor and the estimated value of the centroid height , that is .

[0050] Anti-rollover control method applicable to manual and autonomous tractors. For step S10: Calculate the roll torque of the tractor , introduce the operating speed of the tractor , roll angle , lateral acceleration , total mass of the tractor and centroid height parameters to obtain the roll torque of the tractor .

[0051] Anti-rollover control method applicable to manual and autonomous tractors. For step S11, calculate the roll torque margin of the moment gyro , comprehensively consider the roll angle of the tractor , roll torque , angle of the moment gyro base motor , and rotational speed value of the moment gyro rotor motor to calculate the roll torque margin of the moment gyro .

[0052] Through the above solutions, the corresponding control constraints of the tractor in the autonomous driving mode and the manual driving mode are constructed, namely the two key performance indicators of path tracking accuracy and driving comfort, and they are used as one of the conditions for the multi-objective adaptive control dominated by anti-rollover. This not only ensures that the tractor can achieve anti-rollover control in different driving modes, but also takes into account the performance requirements such as path tracking accuracy and driving comfort, thus realizing the optimization and improvement of the comprehensive performance of the tractor.

[0053] The embodiment of the present invention also provides an anti-rollover system applicable to manual and autonomous tractors. Refer to Figure 3 , including a state acquisition subsystem, a steering subsystem, a moment gyro subsystem and an anti-rollover controller.

[0054] The state acquisition subsystem is responsible for monitoring the state parameters of the tractor. The state acquisition subsystem is electrically connected to the anti-rollover controller and transmits the state parameters to the anti-rollover controller.

[0055] The status acquisition subsystem senses the status of the tractor and sends relevant data to the rollover prevention controller. The rollover prevention controller judges the driving mode and rollover risk level of the tractor, and realizes rollover prevention control that takes rollover prevention as the leading factor and takes into account the requirements of different driving modes through the combined action of the steering subsystem and the torque gyroscope subsystem.

[0056] The rollover prevention controller uses the 32-bit microprocessor STM32F103 as the control core.

[0057] The steering subsystem includes a steering assist motor assembly, a steering column, and a hydraulic steering unit. The steering assist motor assembly is installed on the steering column. The steering column connects the steering wheel and the hydraulic steering unit. The steering assist motor assembly is electrically connected to the rollover prevention controller.

[0058] The torque gyroscope subsystem is installed on the front chassis of the tractor. The torque gyroscope subsystem includes a base motor and a rotor motor, and is electrically connected to the rollover prevention controller.

[0059] Through the above solution, the controllable anti-roll torque of the tractor can be improved, and complex modification of the tractor chassis is avoided, and the cost performance of the rollover prevention system is improved.

[0060] The rollover prevention controller integrates the data information of the status acquisition subsystem, automatically selects the rollover prevention control strategy under different driving modes, and realizes multi-objective adaptive control with rollover prevention as the leading factor through the torque gyroscope subsystem and the steering subsystem.

[0061] The status acquisition subsystem is equipped with a Hall speed sensor, a pose sensor, a pressure sensor, a steering column torque and angle sensor, a magnetic encoder and an optical encoder to monitor the status parameters of the tractor in real time. The status parameter acquisition subsystem can collect the operating speed of the tractor 、roll angle 、lateral acceleration 、suspension hydraulic cylinder pressure 、steering column torque 、steering wheel angle 、base motor angle 、rotor motor speed parameter values.

[0062] The Hall speed sensor selects VB-Z9400 and is installed near the rear axle of the tractor for detecting the operating speed of the tractor.

[0063] The pose sensor selects the six-axis gyroscope JY61 module for detecting the roll angle and lateral acceleration of the tractor.

[0064] The pressure sensor selects the Rexroth pressure sensor HM20 for detecting the suspension hydraulic cylinder pressure.

[0065] The steering column torque and rotation angle sensor selects the Hella non-contact rotation angle torque sensor, which is used to detect the torque and rotation angle of the steering column and convert them into the steering wheel rotation angle.

[0066] The rotation angle of the motor selects the AS5600 magnetic encoder module, which is used to detect the rotation angle of the torque gyro base.

[0067] The motor speed selects the HKT30301 optical encoder, which is used to detect the rotation speed of the torque gyro rotor.

[0068] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A rollover prevention control method applicable to manual and automatic driving tractors, characterized in that: The anti-rollover control method adopts a front wheel steering and moment gyro joint control mode, and can predict the rollover risk based on the tractor rollover risk evaluation index and the moment gyro control margin according to the real-time status of the tractor and the moment gyro; and realize the anti-rollover control of the front wheel steering and the moment gyro joint under the high rollover risk state; Under low rollover risk conditions, adaptive coordinated control of rollover prevention and path tracking is achieved in automatic driving mode, and adaptive coordinated control of rollover prevention and driving comfort is achieved in manual driving mode.

2. The rollover prevention control method applicable to manual and automatic driving tractors according to claim 1, characterized in that: The following steps are involved: S1: Collect and process the state parameters related to the tractor, front wheel angle and torque gyro, including the tractor operating speed , roll angle , lateral acceleration , Suspension hydraulic cylinder pressure , Steering column torque , steering wheel angle , torque gyro base motor angle , torque gyro rotor motor speed ; S2: Estimation of the total mass of the tractor based on the suspension hydraulic cylinder pressure ; S3: According to the tractor tilt angle and estimated gross tractor mass Estimating the tractor center of mass height ; S4: Calculation of tractor rollover risk assessment index ; S5: Based on the tractor rollover risk assessment index Determine the risk level of tractor rollover: If , the rollover risk is high, then the anti-rollover control combined with the front wheel steering and the moment gyro is implemented, and step S6 is executed; if , the rollover risk is low, and the tractor roll torque value and the moment gyro anti-roll torque margin need to be calculated and compared as a supplement to the tractor rollover risk evaluation index, which is used to further judge the rollover risk and control it according to the high or low risk level; S6: Establish the joint anti-rollover control constraint condition 1, i.e., the maximum steering angle of the tractor, the maximum rotation angle of the moment gyro base, and the maximum speed constraint of the moment gyro rotor, as the basic condition for the stability control with the anti-rollover as the goal; S7: The control method provided has different control strategies for different rollover risk levels and different driving modes, and each control strategy allocates the front wheel steering angle and the torque output value of the moment gyro by the corresponding LQR controller; under the high rollover risk state, based on the constraint condition 1 established in S6, the joint anti-rollover control strategy allocates the front wheel steering angle and the torque output value of the moment gyro by using the LQR controller 1; S8: Taking the front wheel steering angle assigned by the LQR controller as the desired value, fast tracking of the desired front wheel steering angle is achieved through closed-loop control; S9: Taking the output torque of the moment gyro allocated by the LQR controller as the desired value, closed-loop control is performed on the base angle and rotor speed of the moment gyro to achieve rapid tracking of the desired output torque of the moment gyro.

3. The rollover prevention control method applicable to manual and automatic driving tractors according to claim 2, characterized in that: The step S5, under the low rollover risk state, needs to calculate and compare the tractor roll torque value and the moment gyro anti-roll torque margin as a supplement to the tractor rollover risk evaluation index, for further judging the rollover risk, and controlling according to the high or low judged risk level, specifically including the following steps: S10: Calculation of tractor roll torque , as a parameter for determining the degree of rollover and the intervention of anti-rollover control; S11: Calculate the moment gyro anti-roll torque margin ; S12: Comparing tractor roll torque and moment gyro anti-roll torque margin ,if , the tractor has no risk of rollover, then return to S1; if , if the tractor is in a low-risk rollover state but requires rollover prevention control intervention, execute S13; S13: If , the risk of the tractor rolling over is high, the anti-rollover control combined with the front wheel steering and the torque gyro is implemented, and S6 is executed; if , the risk of the tractor rolling over is low, and the corresponding control strategy is implemented according to the driving mode.

4. The rollover prevention control method applicable to manual and automatic driving tractors according to claim 3, characterized in that: In step S13, if the risk of the tractor rolling over is low, a corresponding control strategy is implemented according to the driving mode, including the following steps: S14: When the tractor is in a low-risk rollover state, the control method automatically determines the driving mode and implements adaptive coordinated control of the work quality or driving experience. First, the torque signal of the tractor steering column is processed to determine the torque magnitude and direction; S15: determining whether the current mode of the tractor is automatic driving or manual driving; S16: If the tractor is in the automatic driving mode, then establish constraint 2 in the automatic driving mode with low rollover risk; that is, based on the tractor operating speed and lateral acceleration Set the maximum change in the front wheel angle within the path tracking error range ; S17: Based on the constraint condition 2 in the automatic driving mode established in S16, the LQR controller 2 is used to allocate the front wheel steering angle and the torque output torque of the moment gyro with the rollover prevention as the main factor and the path tracking accuracy as the consideration, and then S8 and S9 are executed; S18: If the tractor is in manual driving mode, then establish constraint 3 in low rollover risk, manual driving mode; that is, according to the steering column torque , steering wheel angle and angular velocity Identify driver intentions and establish a front wheel steering range that meets driving comfort and driving intentions ; S19: Based on the constraint condition 3 in the manual driving mode established in S18, the LQR controller 3 is used to allocate the front wheel steering angle and the torque gyro output torque that are dominated by rollover prevention and take driving intention and comfort into consideration, and then S8 and S9 are executed.

5. The rollover prevention control method applicable to manual and automatic driving tractors according to claim 2, characterized in that: Step S4: Calculating the tractor rollover risk assessment index , the index is calculated based on the tractor's roll angle and an estimate of the centroid height ,Right now .

6. The rollover prevention control method applicable to manual and automatic driving tractors according to claim 3, characterized in that: Step S10: Calculating the tractor roll torque , introducing tractor operating speed , roll angle , lateral acceleration , Total mass of the pulling machine and centroid height Parameters, get the tractor roll torque .

7. The rollover prevention control method applicable to manual and automatic driving tractors according to claim 3, characterized in that: The step S11 is to calculate the anti-roll torque margin of the moment gyro , taking into account the tractor roll angle , roll torque , torque gyro base motor angle and torque gyro rotor motor speed value , calculate the moment gyro anti-roll torque margin .

8. An anti-rollover system for manual and automatic driving tractors according to any one of claims 1 to 7, characterized in that: The anti-rollover system includes a state acquisition subsystem, a steering subsystem, a moment gyro subsystem and an anti-rollover controller; The state acquisition subsystem is responsible for monitoring the state parameters of the tractor. The state acquisition subsystem is electrically connected to the anti-rollover controller and transmits the state parameters to the anti-rollover controller. The steering subsystem includes a power steering motor assembly, a steering column, and a hydraulic steering unit. The power steering motor assembly is mounted on the steering column. The steering column is connected to the steering wheel and the hydraulic steering unit. The power steering motor assembly is electrically connected to the anti-rollover controller. The torque gyro subsystem is installed on the front chassis of the tractor. The torque gyro subsystem includes a base motor and a rotor motor, and is electrically connected to the anti-rollover controller; The anti-rollover controller integrates data information of the state acquisition subsystem, automatically selects anti-rollover control strategies under different driving modes, and realizes multi-objective adaptive control dominated by anti-rollover through the torque gyro subsystem and the steering subsystem.

9. The rollover prevention system for manual and automatic driving tractors according to claim 8, characterized in that: The state acquisition subsystem is equipped with a Hall speed sensor, a posture sensor, a pressure sensor, a steering column torque and angle sensor, a magnetic encoder and a photoelectric encoder to monitor the state parameters of the tractor and the anti-rollover actuator in real time and to collect the tractor operating speed. , roll angle , lateral acceleration , Suspension hydraulic cylinder pressure , Steering column torque , steering wheel angle , base motor angle , rotor motor speed Parameter value.

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