Intelligent hydraulic braking method and system for trailer

Abstract

This invention discloses an intelligent hydraulic braking method and system for trailers, relating to the field of trailer braking technology. The method includes: acquiring braking signals and calculating the trailer's braking pressure requirements; calculating the motor's torque requirements and the solenoid valve's PWM signal requirements; adjusting the motor's output torque in real time to adjust the braking pressure; outputting the required braking pressure to the brakes on the trailer wheels for follow-up braking; identifying wheel lock-up and vehicle body sway; determining the wheels to be controlled and the required control mode; and controlling the brakes on the trailer wheels. This invention, by acquiring braking requirements, braking pressure requirements, and information on trailer wheel lock-up and vehicle body sway, outputs the required hydraulic braking force to the trailer's brakes. This not only achieves follow-up braking to ensure trailer braking safety but also provides anti-lock braking and trailer stabilization, ensuring driving stability and ride comfort.

Description

Technical Field

[0001] The present invention relates to the technical field of trailer braking, and in particular to an intelligent hydraulic braking method and system for a trailer. Background Art

[0002] As the market share of trailer vehicles, including electric sightseeing trains, trailer RVs, trailer vehicle transport platforms and other products increases, more problems are exposed. Among them, the braking system is particularly prominent and seriously affects safety.

[0003] The existing braking systems of trailer vehicles include impact brakes, electromagnetic brakes, and electro-hydraulic brakes. Impact brakes, also known as overrun brake systems, are used when the tractor brakes. The trailer relies on inertia to squeeze the trailer ball and shock-absorbing spring in the impact brake system, thereby squeezing the brake pump piston rod and pushing the power-assisting oil to the brake cylinder, thereby braking the trailer. However, impact brakes will exert a large impact force on the tractor during a collision, which may cause the tractor's braking force to disappear, posing a great challenge to the safety of the tractor. Impact brakes are passive brakes, and the driver cannot control the force. Braking is impossible when climbing a slope. In some extreme cases, such as driving too fast, braking on a curve, or reversing from a slope down a slope, there is a certain degree of danger.

[0004] Electromagnetic brakes control the brake electromagnet of the trailer through the current of the synchronizer on the tractor to brake the trailer. It can achieve braking with the vehicle in front, but the braking strength of the electromagnetic brake is low. As the weight of the trailer increases, the braking function of the existing electromagnetic brake can no longer completely stop the trailer, which poses a danger to the driver's life and vehicle safety. The existing electronically controlled hydraulic brakes also control the motor and solenoid valve in the hydraulic brake system of the trailer through the current of the synchronizer on the tractor, and deliver the brake fluid to the slave pump, thereby achieving hydraulic braking of the trailer. Both electromagnetic brakes and existing electronically controlled hydraulic brake systems rely on the current control signal of the synchronizer. Once the synchronizer fails, the brakes of the trailer fail, which brings great risks to the tractor and trailer. Summary of the invention

[0005] The present invention provides a trailer intelligent hydraulic braking method and system, which are used to overcome at least one technical problem existing in the prior art.

[0006] In one aspect, the present invention provides an intelligent hydraulic braking method for a trailer, comprising:

[0007] Collecting a brake signal, wherein the brake signal includes a brake switch signal and an IMU signal of the tractor;

[0008] Determine whether there is a braking demand according to the braking signal, and when there is no braking demand, return to the step of collecting the braking signal; when there is a braking demand, calculate the braking pressure demand of the trailer according to the IMU signal of the tractor;

[0009] Calculating the torque requirement of the motor and the PWM signal requirement of the solenoid valve according to the brake pressure requirement;

[0010] According to the torque requirement of the motor and the PWM signal requirement of the solenoid valve, the motor is controlled to output the corresponding torque, and the solenoid valve is driven to output the required braking pressure to the brake on the wheel of the trailer to perform the following braking of the trailer;

[0011] collecting a pressure sensor signal of a hydraulic unit, and when the pressure sensor signal does not reach the required brake pressure, adjusting the output torque of the motor to adjust the brake pressure;

[0012] Collecting IMU signals and wheel speed sensor signals of the trailer;

[0013] Identifying wheel locking and body swing of the trailer according to the IMU signal and wheel speed sensor signal of the trailer;

[0014] According to the wheel locking condition and body swing condition of the trailer, determine the wheel to be controlled and the required control mode, and calculate the motor torque and the driving signal of the corresponding solenoid valve;

[0015] The brakes on the wheels of the trailer are controlled according to the motor torque and the driving signal of the corresponding solenoid valve.

[0016] Optionally, judging whether there is a braking requirement according to the braking signal is specifically as follows:

[0017] Determine whether the brake switch signal is a valid signal. If it is not a valid signal, it indicates that there is no braking requirement. If it is a valid signal, compare the deceleration of the tractor with the deceleration threshold. When the deceleration of the tractor is less than or equal to the deceleration threshold, it indicates that there is no braking requirement. When the deceleration of the tractor is greater than the deceleration threshold, it indicates that there is a braking requirement.

[0018] Optionally, the braking pressure requirement of the trailer is calculated according to the IMU signal of the tractor, specifically:

[0019] Acquiring the deceleration of the tractor according to the IMU signal of the tractor;

[0020] Calculating the braking intensity of the tractor according to the deceleration of the tractor;

[0021] Calculating the ground braking force according to the braking intensity;

[0022] According to the ground braking force, the braking force of the brake is calculated;

[0023] The braking pressure requirement of the trailer is calculated according to the braking force of the brake.

[0024] Optionally, the wheel locking condition of the trailer is identified according to the IMU signal and the wheel speed sensor signal of the trailer, specifically:

[0025] Acquire longitudinal acceleration, lateral acceleration and yaw rate information according to the IMU signal of the trailer;

[0026] The wheel speed sensor signal, longitudinal acceleration, lateral acceleration and yaw rate information are integrated to obtain the real ground speed of the wheel;

[0027] determining a slip ratio according to a difference between a true ground speed of the wheel and a vehicle speed;

[0028] A wheel locking situation of the trailer vehicle is detected based on the slip ratio.

[0029] Optionally, according to the IMU signal and the wheel speed sensor signal of the trailer, the body swing of the trailer is identified, specifically:

[0030] The integral gyroscope in the IMU is used to collect angular velocity data to obtain the rotation angle of the vehicle relative to the initial position;

[0031] Using the accelerometer in the IMU to collect the vehicle's attitude changes, the attitude changes include pitch, roll and yaw;

[0032] The swing condition of the vehicle is determined according to the rotation angle and the posture change.

[0033] On the other hand, the present invention also provides an intelligent hydraulic brake system for a trailer, comprising:

[0034] A first acquisition module, used for acquiring a brake signal, wherein the brake signal includes a brake switch signal and an IMU signal of the tractor;

[0035] A first judgment module is used to judge whether there is a braking demand according to the braking signal, and when there is no braking demand, return to the step of collecting the braking signal; when there is a braking demand, calculate the braking pressure demand of the trailer according to the IMU signal of the tractor;

[0036] A first calculation module, used for calculating the torque requirement of the motor and the PWM signal requirement of the solenoid valve according to the brake pressure requirement;

[0037] A first control module, used for controlling the motor to output a corresponding torque according to the torque requirement of the motor and the PWM signal requirement of the solenoid valve, and driving the solenoid valve to output a required braking pressure to the brakes on the wheels of the trailer to perform follow-up braking of the trailer;

[0038] A second acquisition module is used to acquire a pressure sensor signal of the hydraulic unit, and when the pressure sensor signal does not reach the required brake pressure, adjust the output torque of the motor to adjust the brake pressure;

[0039] A third acquisition module, used to collect the IMU signal and wheel speed sensor signal of the trailer;

[0040] An identification module, used for identifying the wheel locking condition and body swing condition of the trailer according to the IMU signal and wheel speed sensor signal of the trailer;

[0041] A determination module, used to determine the wheels to be controlled and the required control mode according to the wheel locking condition and body swing condition of the trailer, and calculate the motor torque and the driving signal of the corresponding solenoid valve;

[0042] The second control module is used to control the brakes on the wheels of the trailer according to the motor torque and the driving signal of the corresponding solenoid valve.

[0043] Optionally, the first determination module is specifically configured to:

[0044] Determine whether the brake switch signal is a valid signal. If it is not a valid signal, it indicates that there is no braking requirement. If it is a valid signal, compare the deceleration of the tractor with the deceleration threshold. When the deceleration of the tractor is less than or equal to the deceleration threshold, it indicates that there is no braking requirement. When the deceleration of the tractor is greater than the deceleration threshold, it indicates that there is a braking requirement.

[0045] Optionally, when there is a braking demand, the first judgment module includes:

[0046] An acquisition module, used for acquiring the deceleration of the tractor according to the IMU signal of the tractor;

[0047] A second calculation module, used for calculating the braking intensity of the tractor according to the deceleration of the tractor;

[0048] A third calculation module, used for calculating the ground braking force according to the braking intensity;

[0049] A fourth calculation module, used for calculating the braking force of the brake according to the ground braking force;

[0050] The fifth calculation module is used to calculate the braking pressure requirement of the trailer according to the braking force of the brake.

[0051] Optionally, the identification module is specifically used to:

[0052] Acquire longitudinal acceleration, lateral acceleration and yaw rate information according to the IMU signal of the trailer;

[0053] The wheel speed sensor signal, longitudinal acceleration, lateral acceleration and yaw rate information are integrated to obtain the real ground speed of the wheel;

[0054] determining a slip ratio according to a difference between a true ground speed of the wheel and a vehicle speed;

[0055] A wheel locking situation of the trailer vehicle is detected based on the slip ratio.

[0056] Optionally, the identification module is specifically used to:

[0057] The integral gyroscope in the IMU is used to collect angular velocity data to obtain the rotation angle of the vehicle relative to the initial position;

[0058] Using the accelerometer in the IMU to collect the vehicle's attitude changes, the attitude changes include pitch, roll and yaw;

[0059] The swing condition of the vehicle is determined according to the rotation angle and the posture change.

[0060] The innovative features of the embodiments of the present invention include:

[0061] 1. In this embodiment, the braking demand and the braking pressure demand are obtained through the braking signal, i.e., the brake switch signal and the IMU signal of the tractor, and the motor torque demand and the PWM signal demand of the solenoid valve are calculated based on the braking pressure demand, so as to control the drive module to control the motor and the solenoid valve, output the required hydraulic braking force to the brake on the trailer wheel, realize the trailer following braking function, and ensure the braking safety of the trailer, which is one of the innovative points of the embodiment of the present invention.

[0062] 2. In this embodiment, a pressure sensor is used to monitor the brake pressure. If the collected pressure sensor signal does not reach the required brake pressure, the drive current of the motor is adjusted to adjust the output torque. When the output torque changes, the output brake pressure changes accordingly, realizing closed-loop control, which is one of the innovations of the embodiment of the present invention.

[0063] 3. In this embodiment, the wheel locking condition and body swing condition of the trailer are obtained through the trailer IMU signal and the trailer wheel speed sensor signal, the wheel that needs to be controlled and the required control mode are determined, and the drive signal of the corresponding solenoid valve is calculated. Then, the drive module is controlled to control the motor and the solenoid valve to control the brakes on the trailer wheels, thereby realizing the anti-lock function of the trailer and the function of stabilizing the trailer, ensuring the driving stability and driving comfort, which is one of the innovations of the embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0065] Figure 1 A flow chart of an intelligent hydraulic braking method for a trailer provided by an embodiment of the present invention;

[0066] Figure 2 A flow chart for calculating the braking pressure requirement of a trailer provided by an embodiment of the present invention;

[0067] Figure 3 A flow chart for identifying wheel locking of a trailer provided by an embodiment of the present invention;

[0068] Figure 4 A flow chart for identifying the body swing of a trailer provided by an embodiment of the present invention;

[0069] Figure 5 A schematic diagram of the structure of an intelligent hydraulic brake system for a trailer provided by an embodiment of the present invention;

[0070] Figure 6 A structural schematic diagram of a first judgment module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0071] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present invention and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0073] The embodiment of the present invention discloses a trailer intelligent hydraulic braking method and system, which are described in detail below.

[0074] Figure 1 For a flow chart of the intelligent hydraulic braking method for a trailer provided by an embodiment of the present invention, please refer to Figure 1 The intelligent hydraulic braking method for a trailer provided by an embodiment of the present invention includes:

[0075] Step 1: Collect brake signals, which include brake switch signals and IMU (Inertial Measurement Unit) signals of the tractor;

[0076] Step 2: Determine whether there is a braking demand based on the braking signal. If there is no braking demand, return to the step of collecting braking signals. If there is a braking demand, calculate the braking pressure demand of the trailer based on the IMU signal of the tractor.

[0077] Step 3: Calculate the torque requirement of the motor and the PWM signal requirement of the solenoid valve according to the brake pressure requirement;

[0078] Step 4: According to the torque requirement of the motor and the PWM signal requirement of the solenoid valve, the motor is controlled to output the corresponding torque, and the solenoid valve is driven to output the required braking pressure to the brake on the trailer wheel to perform the following braking of the trailer;

[0079] Step 5: Collect the pressure sensor signal of the hydraulic unit. When the pressure sensor signal does not reach the required brake pressure, adjust the output torque of the motor to adjust the brake pressure;

[0080] Step 6: Collect the IMU signal and wheel speed sensor signal of the trailer;

[0081] Step 7: Identify the wheel locking and body swing of the trailer according to the IMU signal and wheel speed sensor signal of the trailer;

[0082] Step 8: According to the wheel locking condition and body swing condition of the trailer, determine the wheel to be controlled and the required control mode, and calculate the motor torque and the driving signal of the corresponding solenoid valve;

[0083] Step 9: The brakes on the trailer wheels are controlled according to the motor torque and the driving signal of the corresponding solenoid valve.

[0084] Specifically, please refer to Figure 1 In the intelligent hydraulic braking method for trailers provided by the present invention, when the tractor brakes, a brake signal is generated, and the brake signal includes a brake switch signal and an IMU signal of the tractor. At this time, the control unit of the intelligent hydraulic control system of the trailer collects the above brake signal through step 1. And in step 2, it is determined whether there is a braking demand according to the collected brake signal.

[0085] When judging whether there is a braking demand, the present invention performs redundant verification through the brake switch signal and the IMU signal of the tractor. First, it is judged whether the collected brake switch signal is a valid signal. If the brake switch signal is not a valid signal, it means that there is no braking demand. At this time, it can return to step 1 and perform the above operation again.

[0086] If the brake switch signal is a valid signal, the collected IMU signal of the tractor is used for redundant verification. First, according to the signal is a valid signal, the deceleration of the tractor is extracted using the collected IMU signal of the tractor, and then the deceleration is compared with the deceleration threshold to further confirm whether there is a braking demand. When the deceleration of the tractor is less than or equal to the deceleration threshold, it means that there is no braking demand, return to step 1, and perform the above operation again; when the deceleration of the tractor is greater than the deceleration threshold, it means that there is a braking demand and the trailer needs to be braked. Therefore, it is necessary to calculate the braking pressure demand of the trailer based on the IMU signal of the tractor, so as to output the corresponding braking pressure to the brake of the trailer to achieve the follow-up braking of the trailer.

[0087] The magnitude of the brake pressure is related to the motor torque and the PWM signal driving the solenoid valve. Therefore, it is necessary to calculate the motor torque requirement and the solenoid valve PWM signal requirement based on the brake pressure requirement in step 3. And in step 4, the motor is controlled to output the required motor torque calculated in step 3, and the solenoid valve is driven, so as to output the required brake pressure to the brake on the trailer wheel, so as to realize the follow-up brake of the trailer.

[0088] The present invention obtains the braking demand and the braking pressure demand through the braking signal, i.e., the brake switch signal and the IMU signal of the tractor, and calculates the motor torque demand and the PWM signal demand of the solenoid valve based on the braking pressure demand, thereby controlling the drive module to control the motor and the solenoid valve, outputting the required hydraulic braking force to the brakes on the wheels of the trailer, realizing the trailer following braking function, and ensuring the braking safety of the trailer.

[0089] In order to ensure the braking effect of the trailer, after the brake pressure is output to the wheels of the trailer, the present invention collects the pressure sensor signal of the hydraulic unit through step 5, and uses the pressure sensor to monitor the brake pressure. If the collected pressure sensor signal does not reach the required brake pressure, the driving current of the motor is adjusted to adjust the output torque. When the output torque changes, the output brake pressure changes accordingly to achieve closed-loop control. For example, if the collected pressure sensor signal is less than the required brake pressure, the motor is controlled to output a larger current to increase the output torque, thereby increasing the output brake pressure. In this way, closed-loop control of the trailer braking can be achieved.

[0090] During the braking process of the trailer, wheel locking and body swaying may occur. In order to prevent the above situation from occurring, it is necessary to identify the wheel locking and body swaying of the trailer in real time. Therefore, the present invention collects the IMU signal and wheel speed sensor signal of the trailer in step 6, and then in step 7, identifies the wheel locking and body swaying of the trailer according to the collected IMU signal and wheel speed sensor signal of the trailer.

[0091] The slip rate is an indicator to measure the degree of wheel slip, which indicates the proportion of wheel slip in the longitudinal movement of the wheel. Under normal driving conditions, the slip rate is 0, indicating that the wheel is rolling normally; when the slip rate is 100%, it means that the wheel is locked and the car is in a dragging state. Therefore, the wheel locking of the trailer can be identified by calculating the slip rate. The body swing of the vehicle, such as the vehicle's posture change, rotation angle, and movement state, can be identified through the measurement data of the gyroscope and accelerometer in the IMU.

[0092] After obtaining the wheel locking and body swing of the trailer, the wheels to be controlled and the required control mode can be determined in step 8 according to the wheel locking and body swing of the trailer. For example, if a wheel is identified to be locked, the ABS system will immediately perform decompression control on the wheel and release the brake to allow the wheel to roll again. When the wheel rolls again, the ABS system will perform boost control again and apply the brake; and so on, repeatedly performing the braking-relaxing operation until the wheel resumes normal rotation.

[0093] The motor torque and the driving signal of the corresponding solenoid valve are calculated at the same time, and the brakes on the trailer wheels are controlled according to the motor torque and the driving signal of the corresponding solenoid valve in step 9. When pressure reduction is required, the pressure relief valve is controlled to release pressure; and when pressure increase is required, the motor is controlled to increase pressure, thereby realizing the anti-lock function and the function of stabilizing the trailer.

[0094] The present invention obtains the wheel locking condition and body swing condition of the trailer through the trailer IMU signal and the trailer wheel speed sensor signal, determines the wheel that needs to be controlled and the required control mode, and calculates the driving signal of the corresponding solenoid valve, and then controls the driving module to control the motor and the solenoid valve to control the brakes on the trailer wheels, thereby realizing the anti-lock function of the trailer and the function of stabilizing the trailer, and ensuring the driving stability and driving comfort.

[0095] Optionally, Figure 2 For a flow chart of calculating the brake pressure requirement of a trailer provided by an embodiment of the present invention, please refer to Figure 1 and Figure 2 In step 2, the braking pressure requirement of the trailer is calculated according to the IMU signal of the tractor, specifically: step 21, the deceleration of the tractor is obtained according to the IMU signal of the tractor; step 22, the braking strength of the tractor is calculated according to the deceleration of the tractor; step 23, the ground braking force is calculated according to the braking strength; step 24, the braking force of the brake is calculated according to the ground braking force; step 25, the braking pressure requirement of the trailer is calculated according to the braking force of the brake.

[0096] Specifically, please refer to Figure 2 The braking pressure requirement of the trailer is related to the urgency of braking, and the urgency of braking is related to the deceleration of the tractor. Therefore, when calculating the braking pressure requirement of the trailer, it is necessary to obtain the deceleration of the tractor according to the IMU signal of the tractor in step 21. Then, in step 22, the braking strength of the tractor is calculated according to the deceleration of the tractor. The greater the deceleration, the higher the urgency of braking, and the higher the braking strength of the corresponding tractor.

[0097] In step 23, the ground braking force can be calculated according to the braking intensity. Then, in step 24, the braking force of the brake is calculated using the ground braking force calculated in the previous step. After the braking force of the brake is obtained, the braking pressure requirement of the trailer can be calculated using the braking force of the brake in step 25.

[0098] Optionally, Figure 3 For a flow chart of identifying wheel locking of a trailer provided by an embodiment of the present invention, please refer to Figure 1 and Figure 3In step 7, the wheel locking condition of the trailer is identified according to the IMU signal and the wheel speed sensor signal of the trailer, specifically: step 71, obtaining the longitudinal acceleration, lateral acceleration and yaw rate information according to the IMU signal of the trailer; step 72, fusing the wheel speed sensor signal, the longitudinal acceleration, the lateral acceleration and the yaw rate information to obtain the real ground speed of the wheel; step 73, determining the slip rate according to the difference between the real ground speed of the wheel and the vehicle speed; step 74, identifying the wheel locking condition of the trailer according to the slip rate.

[0099] Specifically, please refer to Figure 3 In order to prevent wheel locking, it is necessary to identify the wheel status of the trailer in real time. The slip rate is an indicator to measure the degree of wheel slip, so the wheel locking of the trailer can be identified by calculating the slip rate.

[0100] Usually, the difference between the wheel speed and the vehicle speed can be calculated by the wheel speed sensor signal to obtain the slip ratio. In this embodiment, in order to improve the accuracy of slip ratio calculation, the wheel speed signal and IMU data are integrated to estimate the true ground speed of each wheel.

[0101] First, in step 71, the longitudinal acceleration, lateral acceleration and yaw rate information are obtained according to the IMU signal of the trailer. Then, in step 72, the wheel speed sensor signal, longitudinal acceleration, lateral acceleration and yaw rate information are integrated through the extended Kalman filter (EKF) method to obtain the true ground speed of each wheel.

[0102] After obtaining the real ground speed of the wheel, in step 73, the slip ratio of the corresponding wheel can be calculated according to the difference between the real ground speed of the wheel and the vehicle speed. Finally, in step 74, the wheel locking condition of the trailer can be identified according to the slip ratio. When the slip ratio is 0, it means that the wheel is rolling normally and the vehicle is in a normal driving state. When the slip ratio is 100%, it means that the wheel is locked and the vehicle is in a dragging state.

[0103] Optionally, Figure 4 For a flow chart of identifying the body swing of a trailer provided by an embodiment of the present invention, please refer to Figure 1 and Figure 4 In step 7, the body swing of the trailer is identified according to the IMU signal and wheel speed sensor signal of the trailer, specifically: step 071, using the integral gyroscope in the IMU to collect angular velocity data to obtain the rotation angle of the vehicle relative to the initial position; step 072, using the accelerometer in the IMU to collect the attitude change of the vehicle, the attitude change includes pitch, roll and yaw; step 073, judging the swing of the vehicle according to the rotation angle and attitude change.

[0104] Specifically, please refer to Figure 4 In order to prevent the body from swinging, it is necessary to identify the body state of the trailer in real time. The body state can be identified by IMU, which mainly relies on the measurement data of the gyroscope and accelerometer in IMU.

[0105] The gyroscope can measure the angular velocity of an object around each axis, that is, the rotation speed of the object per unit time. By integrating the angular velocity data output by the gyroscope, the rotation angle of the object relative to the initial position can be obtained. Therefore, in step 071 of this embodiment, the integral gyroscope in the IMU is used to collect angular velocity data, thereby obtaining the rotation angle of the vehicle relative to the initial position, and the rotation angle can be used to determine the swing of the vehicle.

[0106] The accelerometer can measure the acceleration of an object due to the earth's gravity or the movement of the object, that is, the rate of change of the speed of the object per unit time. By measuring the readings of the accelerometer on each axis, the attitude change of the object can be determined. Therefore, in step 072 of this embodiment, the attitude change of the vehicle, such as pitch, roll and yaw, is obtained by measuring the readings of the accelerometer in the IMU on each axis.

[0107] Step 073, by comprehensively analyzing the rotation angle and attitude change data collected by the integral gyroscope and the accelerometer, the swing of the vehicle is determined. Compared with determining the swing of the vehicle body only by the rotation angle, the comprehensive analysis can more accurately determine the swing of the vehicle.

[0108] Specific comprehensive analysis of the situation For example, if the IMU detects "rolling to the right, yaw to the right, pitching forward", and "deceleration in the front and rear directions", it can be judged that the vehicle is in a right-angle entry-turning state. If these states gradually intensify, it can be judged that the vehicle is in an approaching state while decelerating; if these states are stable and do not change much, it can be judged that the vehicle is in a turning state. If the roll changes from here to the upright direction and accelerates forward, it can be inferred that the vehicle is rising. If the yaw rate suddenly increases during this turn, it can be inferred that the rear wheels are slipping and swinging outward. In summary, the measurement data of the gyroscope and accelerometer in the IMU can effectively identify the body swing of the vehicle, including the vehicle's posture changes, rotation angle, and motion state.

[0109] Based on the same inventive concept, the present invention also provides an intelligent hydraulic braking system for a trailer. Figure 5 A schematic diagram of a structure of an intelligent hydraulic brake system for a trailer provided by an embodiment of the present invention is shown in FIG. Figure 5 The trailer intelligent hydraulic braking system 100 provided by the embodiment of the present invention includes:

[0110] The first acquisition module 101 is used to acquire a brake signal, where the brake signal includes a brake switch signal and an IMU signal of the tractor;

[0111] The first judgment module 102 is used to judge whether there is a braking demand according to the braking signal, and when there is no braking demand, return to the step of collecting the braking signal; when there is a braking demand, calculate the braking pressure demand of the trailer according to the IMU signal of the tractor;

[0112] A first calculation module 103, used to calculate the torque requirement of the motor and the PWM signal requirement of the solenoid valve according to the brake pressure requirement;

[0113] The first control module 104 is used to control the motor to output the corresponding torque according to the torque requirement of the motor and the PWM signal requirement of the solenoid valve, and drive the solenoid valve to output the required braking pressure to the brakes on the wheels of the trailer to perform the following braking of the trailer;

[0114] The second acquisition module 105 is used to acquire the pressure sensor signal of the hydraulic unit, and when the pressure sensor signal does not reach the required brake pressure, adjust the output torque of the motor to adjust the brake pressure;

[0115] The third acquisition module 106 is used to collect the IMU signal and wheel speed sensor signal of the trailer;

[0116] The identification module 107 is used to identify the wheel locking condition and body swing condition of the trailer according to the IMU signal and wheel speed sensor signal of the trailer;

[0117] A determination module 108, for determining the wheels to be controlled and the required control mode according to the wheel locking condition and body swing condition of the trailer, and calculating the motor torque and the driving signal of the corresponding solenoid valve;

[0118] The second control module 109 is used to control the brakes on the wheels of the trailer according to the motor torque and the driving signal of the corresponding solenoid valve.

[0119] Specifically, please refer to Figure 5 The intelligent hydraulic brake system for trailers provided by the present invention generates a brake signal when the tractor brakes, and the brake signal includes a brake switch signal and an IMU signal of the tractor. At this time, the control unit of the intelligent hydraulic control system for trailers collects the brake signal through the first acquisition module 101. The first judgment module 102 is used to judge whether there is a braking demand according to the collected brake signal.

[0120] When judging whether there is a need for braking, the present invention performs redundant verification through the brake switch signal and the IMU signal of the tractor. First, it is judged whether the collected brake switch signal is a valid signal. If the brake switch signal is not a valid signal, it means that there is no need for braking. At this time, the above operation can be performed again.

[0121] If the brake switch signal is a valid signal, the collected IMU signal of the tractor is used for redundant verification. First, based on the signal, the deceleration of the tractor is extracted using the collected IMU signal of the tractor, and then the deceleration is compared with the deceleration threshold to further confirm whether there is a braking demand. When the deceleration of the tractor is less than or equal to the deceleration threshold, it means that there is no braking demand, and the above operation is performed again; when the deceleration of the tractor is greater than the deceleration threshold, it means that there is a braking demand and the trailer needs to be braked. Therefore, it is necessary to calculate the braking pressure demand of the trailer based on the IMU signal of the tractor, so as to output the corresponding braking pressure to the brake of the trailer to achieve follow-up braking of the trailer.

[0122] The magnitude of the brake pressure is related to the motor torque and the PWM signal driving the electromagnetic valve. Therefore, the first calculation module 103 needs to calculate the motor torque requirement and the electromagnetic valve PWM signal requirement based on the brake pressure requirement. The first control module 104 controls the motor to output the required motor torque calculated above and drives the electromagnetic valve, thereby outputting the required brake pressure to the brake on the trailer wheel, thereby achieving the following brake of the trailer.

[0123] The present invention obtains the braking demand and the braking pressure demand through the braking signal, i.e., the brake switch signal and the IMU signal of the tractor, and calculates the motor torque demand and the PWM signal demand of the solenoid valve based on the braking pressure demand, thereby controlling the drive module to control the motor and the solenoid valve, outputting the required hydraulic braking force to the brakes on the wheels of the trailer, realizing the trailer following braking function, and ensuring the braking safety of the trailer.

[0124] In order to ensure the braking effect of the trailer, after the brake pressure is output to the wheels of the trailer, the present invention collects the pressure sensor signal of the hydraulic unit through the second acquisition module 105, and uses the pressure sensor to monitor the brake pressure. If the collected pressure sensor signal does not reach the required brake pressure, the driving current of the motor is adjusted to adjust the output torque. When the output torque changes, the output brake pressure changes accordingly. For example, if the collected pressure sensor signal is less than the required brake pressure, the motor is controlled to output a larger current to increase the output torque, thereby increasing the output brake pressure. In this way, closed-loop control of the trailer braking can be achieved.

[0125] During the braking process of the trailer, wheel locking and body swaying may occur. In order to prevent the above situation from happening, it is necessary to identify the wheel locking and body swaying of the trailer in real time. Therefore, the present invention collects the IMU signal and wheel speed sensor signal of the trailer through the third acquisition module 106, and then the identification module 107 identifies the wheel locking and body swaying of the trailer according to the collected IMU signal and wheel speed sensor signal of the trailer.

[0126] The slip rate is an indicator to measure the degree of wheel slip, which indicates the proportion of wheel slip in the longitudinal movement of the wheel. Under normal driving conditions, the slip rate is 0, indicating that the wheel is rolling normally; when the slip rate is 100%, it means that the wheel is locked and the car is in a dragging state. Therefore, the wheel locking of the trailer can be identified by calculating the slip rate. The body swing of the vehicle, such as the vehicle's posture change, rotation angle, and movement state, can be identified through the measurement data of the gyroscope and accelerometer in the IMU.

[0127] After obtaining the wheel locking condition and body swing condition of the trailer, the determination module 108 determines the wheel to be controlled and the required control mode according to the wheel locking condition and body swing condition of the trailer. For example, if a wheel is identified to be locked, the ABS system will immediately perform decompression control on the wheel and release the brake to allow the wheel to roll again. When the wheel rolls again, the ABS system will perform boost control again and apply the brake; and so on, the braking-releasing operation is repeated until the wheel resumes normal rotation.

[0128] The motor torque and the driving signal of the corresponding solenoid valve are calculated at the same time, and the second control module 109 controls the brakes on the trailer wheels according to the motor torque and the driving signal of the corresponding solenoid valve. When decompression is required, the pressure relief valve is controlled to release pressure; when pressure is required, the motor is controlled to increase pressure, thereby realizing the anti-lock function and the function of stabilizing the trailer.

[0129] The present invention obtains the wheel locking condition and body swing condition of the trailer through the trailer IMU signal and the trailer wheel speed sensor signal, determines the wheel that needs to be controlled and the required control mode, and calculates the driving signal of the corresponding solenoid valve, and then controls the driving module to control the motor and the solenoid valve to control the brakes on the trailer wheels, thereby realizing the anti-lock function of the trailer and the function of stabilizing the trailer, and ensuring the driving stability and driving comfort.

[0130] Optionally, Figure 6 For a structural diagram of the first judgment module 102 provided in an embodiment of the present invention, please refer to Figure 6When there is a braking demand, the first judgment module 102 includes: an acquisition module 1021, which is used to acquire the deceleration of the tractor according to the IMU signal of the tractor; a second calculation module 1022, which is used to calculate the braking intensity of the tractor according to the deceleration of the tractor; a third calculation module 1023, which is used to calculate the ground braking force according to the braking intensity; a fourth calculation module 1024, which is used to calculate the braking force of the brake according to the ground braking force; a fifth calculation module 1025, which is used to calculate the braking pressure demand of the trailer according to the braking force of the brake.

[0131] Specifically, please refer to Figure 6 The braking pressure requirement of the trailer is related to the urgency of braking, and the urgency of braking is related to the deceleration of the tractor. Therefore, when calculating the braking pressure requirement of the trailer, the acquisition module 1021 acquires the deceleration of the tractor according to the IMU signal of the tractor. Then the second calculation module 1022 calculates the braking strength of the tractor according to the deceleration of the tractor. The greater the deceleration, the higher the urgency of braking, and the corresponding braking strength of the tractor is higher.

[0132] The third calculation module 1023 can calculate the ground braking force according to the braking intensity. The fourth calculation module 1024 uses the ground braking force calculated in the previous step to calculate the braking force of the brake. After obtaining the braking force of the brake, the fifth calculation module 1025 uses the braking force of the brake to calculate the braking pressure requirement of the trailer.

[0133] Optionally, refer to Figure 5 The identification module 107 is specifically used to: obtain longitudinal acceleration, lateral acceleration and yaw rate information according to the IMU signal of the trailer; fuse the wheel speed sensor signal, longitudinal acceleration, lateral acceleration and yaw rate information to obtain the real ground speed of the wheel; determine the slip rate according to the difference between the real ground speed of the wheel and the vehicle speed; and identify the wheel locking condition of the trailer according to the slip rate.

[0134] Specifically, in order to prevent wheel locking, it is necessary to identify the wheel status of the trailer in real time. The slip rate is an indicator to measure the degree of wheel slip, so the wheel locking of the trailer can be identified by calculating the slip rate.

[0135] Usually, the difference between the wheel speed and the vehicle speed can be calculated by the wheel speed sensor signal to obtain the slip ratio. In this embodiment, in order to improve the accuracy of slip ratio calculation, the wheel speed signal and IMU data are integrated to estimate the true ground speed of each wheel.

[0136] First, the longitudinal acceleration, lateral acceleration and yaw rate information are obtained based on the trailer's IMU signal. Then, the extended Kalman filter (EKF) method is used to fuse the wheel speed sensor signal, longitudinal acceleration, lateral acceleration and yaw rate information to obtain the true ground speed of each wheel.

[0137] After obtaining the actual ground speed of the wheel, the slip rate of the corresponding wheel can be calculated based on the difference between the actual ground speed of the wheel and the vehicle speed. Finally, the wheel locking of the trailer can be identified based on the slip rate. When the slip rate is 0, it means that the wheel is rolling normally and the vehicle is in a normal driving state. When the slip rate is 100%, it means that the wheel is locked and the vehicle is in a sliding state.

[0138] Optionally, refer to Figure 5 The identification module 107 is specifically used to: use the integral gyroscope in the IMU to collect angular velocity data to obtain the rotation angle of the vehicle relative to the initial position; use the accelerometer in the IMU to collect the posture changes of the vehicle, the posture changes include pitch, roll and yaw; and judge the swing of the vehicle according to the rotation angle and posture changes.

[0139] Specifically, in order to prevent the body from swinging, it is necessary to identify the body state of the trailer in real time. The body state can be identified by the IMU, which mainly relies on the measurement data of the gyroscope and accelerometer in the IMU.

[0140] The gyroscope can measure the angular velocity of an object around each axis, that is, the rotation speed of the object per unit time. By integrating the angular velocity data output by the gyroscope, the rotation angle of the object relative to the initial position can be obtained. Therefore, this embodiment uses the integral gyroscope in the IMU to collect angular velocity data, thereby obtaining the rotation angle of the vehicle relative to the initial position, and the rotation angle can be used to determine the swing of the vehicle.

[0141] An accelerometer can measure the acceleration of an object due to the earth's gravity or the movement of an object, that is, the rate of change of the object's velocity per unit time. By measuring the readings of the accelerometer on each axis, the attitude change of the object can be determined. Therefore, this embodiment obtains the attitude change of the vehicle, such as pitch, roll, and yaw, by measuring the readings of the accelerometer on each axis in the IMU.

[0142] The vehicle's sway is determined by comprehensively analyzing the rotation angle and attitude change data collected by the integral gyroscope and accelerometer. Compared with judging the vehicle's sway only by the rotation angle, the comprehensive analysis can more accurately determine the vehicle's sway.

[0143] Specific comprehensive analysis of the situation For example, if the IMU detects "rolling to the right, yaw to the right, pitching forward", and "deceleration in the front and rear directions", it can be judged that the vehicle is in a right-angle entry-turning state. If these states gradually intensify, it can be judged that the vehicle is in an approaching state while decelerating; if these states are stable and do not change much, it can be judged that the vehicle is in a turning state. If the roll changes from here to the upright direction and accelerates forward, it can be inferred that the vehicle is rising. If the yaw rate suddenly increases during this turn, it can be inferred that the rear wheels are slipping and swinging outward. In summary, the measurement data of the gyroscope and accelerometer in the IMU can effectively identify the body swing of the vehicle, including the vehicle's posture changes, rotation angle, and motion state.

[0144] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0145] Those skilled in the art can understand that the modules in the device in the embodiment can be distributed in the device in the embodiment according to the description of the embodiment, or can be changed accordingly and located in one or more devices different from the embodiment. The modules in the above embodiment can be combined into one module, or can be further divided into multiple sub-modules.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A trailer intelligent hydraulic braking method, characterized in that: include: Collecting a brake signal, wherein the brake signal includes a brake switch signal and an IMU signal of the tractor; Determine whether there is a braking demand according to the braking signal, and when there is no braking demand, return to the step of collecting the braking signal; when there is a braking demand, obtain the deceleration of the tractor according to the IMU signal of the tractor, calculate the braking intensity of the tractor according to the deceleration of the tractor, calculate the ground braking force according to the braking intensity, calculate the braking force of the brake according to the ground braking force, and calculate the braking pressure demand of the trailer according to the braking force of the brake; Calculating the torque requirement of the motor and the PWM signal requirement of the solenoid valve according to the brake pressure requirement; According to the torque requirement of the motor and the PWM signal requirement of the solenoid valve, the motor is controlled to output the corresponding torque, and the solenoid valve is driven to output the required braking pressure to the brake on the wheel of the trailer to perform the following braking of the trailer; collecting a pressure sensor signal of a hydraulic unit, and when the pressure sensor signal does not reach the required brake pressure, adjusting the output torque of the motor to adjust the brake pressure; Collecting IMU signals and wheel speed sensor signals of the trailer; Identifying wheel locking and body swing of the trailer according to the IMU signal and wheel speed sensor signal of the trailer; According to the wheel locking condition and body swing condition of the trailer, determine the wheel to be controlled and the required control mode, and calculate the motor torque and the driving signal of the corresponding solenoid valve; The brakes on the wheels of the trailer are controlled according to the motor torque and the driving signal of the corresponding solenoid valve.

2. The intelligent hydraulic braking method for trailer according to claim 1, characterized in that: Judging whether there is a braking demand according to the braking signal is as follows: Determine whether the brake switch signal is a valid signal. If it is not a valid signal, it indicates that there is no braking requirement. If it is a valid signal, compare the deceleration of the tractor with the deceleration threshold. When the deceleration of the tractor is less than or equal to the deceleration threshold, it indicates that there is no braking requirement. When the deceleration of the tractor is greater than the deceleration threshold, it indicates that there is a braking requirement.

3. The intelligent hydraulic braking method for trailer according to claim 1, characterized in that: According to the IMU signal and the wheel speed sensor signal of the trailer, the wheel locking condition of the trailer is identified, specifically: Acquire longitudinal acceleration, lateral acceleration and yaw rate information according to the IMU signal of the trailer; The wheel speed sensor signal, longitudinal acceleration, lateral acceleration and yaw rate information are integrated to obtain the real ground speed of the wheel; determining a slip ratio according to a difference between a true ground speed of the wheel and a vehicle speed; A wheel locking situation of the trailer vehicle is detected based on the slip ratio.

4. The intelligent hydraulic braking method for trailer according to claim 1, characterized in that: According to the IMU signal and the wheel speed sensor signal of the trailer, the body swing of the trailer is identified, specifically: The integral gyroscope in the IMU is used to collect angular velocity data to obtain the rotation angle of the vehicle relative to the initial position; Using the accelerometer in the IMU to collect the vehicle's attitude changes, the attitude changes include pitch, roll and yaw; The swing condition of the vehicle is determined according to the rotation angle and the posture change.

5. An intelligent hydraulic brake system for a trailer, characterized in that: include: A first acquisition module, used for acquiring a brake signal, wherein the brake signal includes a brake switch signal and an IMU signal of the tractor; a first judgment module, used to judge whether there is a braking demand according to the braking signal, and when there is no braking demand, return to the step of collecting the braking signal; when there is a braking demand, the first judgment module includes an acquisition module, a second calculation module, a third calculation module, a fourth calculation module and a fifth calculation module, and the acquisition module is used to acquire the deceleration of the tractor according to the IMU signal of the tractor; The second calculation module is used to calculate the braking intensity of the tractor according to the deceleration of the tractor; The third calculation module is used to calculate the ground braking force according to the braking intensity; The fourth calculation module is used to calculate the braking force of the brake according to the ground braking force; The fifth calculation module is used to calculate the braking pressure requirement of the trailer according to the braking force of the brake; A first calculation module, used for calculating the torque requirement of the motor and the PWM signal requirement of the solenoid valve according to the brake pressure requirement; A first control module, used for controlling the motor to output a corresponding torque according to the torque requirement of the motor and the PWM signal requirement of the solenoid valve, and driving the solenoid valve to output a required braking pressure to the brakes on the wheels of the trailer to perform follow-up braking of the trailer; A second acquisition module is used to acquire a pressure sensor signal of the hydraulic unit, and when the pressure sensor signal does not reach the required brake pressure, adjust the output torque of the motor to adjust the brake pressure; A third acquisition module, used to collect the IMU signal and wheel speed sensor signal of the trailer; An identification module, used for identifying the wheel locking condition and body swing condition of the trailer according to the IMU signal and wheel speed sensor signal of the trailer; A determination module, used to determine the wheels to be controlled and the required control mode according to the wheel locking condition and body swing condition of the trailer, and calculate the motor torque and the driving signal of the corresponding solenoid valve; The second control module is used to control the brakes on the wheels of the trailer according to the motor torque and the driving signal of the corresponding solenoid valve.

6. The intelligent hydraulic brake system for trailer according to claim 5, characterized in that: The first judgment module is specifically used for: Determine whether the brake switch signal is a valid signal. If it is not a valid signal, it indicates that there is no braking requirement. If it is a valid signal, compare the deceleration of the tractor with the deceleration threshold. When the deceleration of the tractor is less than or equal to the deceleration threshold, it indicates that there is no braking requirement. When the deceleration of the tractor is greater than the deceleration threshold, it indicates that there is a braking requirement.

7. The intelligent hydraulic brake system for trailer according to claim 5, characterized in that: The identification module is specifically used for: Acquire longitudinal acceleration, lateral acceleration and yaw rate information according to the IMU signal of the trailer; The wheel speed sensor signal, longitudinal acceleration, lateral acceleration and yaw rate information are integrated to obtain the real ground speed of the wheel; determining a slip ratio according to a difference between a true ground speed of the wheel and a vehicle speed; A wheel locking situation of the trailer vehicle is detected based on the slip ratio.

8. The intelligent hydraulic brake system for trailer according to claim 5, characterized in that: The identification module is specifically used for: The integral gyroscope in the IMU is used to collect angular velocity data to obtain the rotation angle of the vehicle relative to the initial position; Using the accelerometer in the IMU to collect the vehicle's attitude changes, the attitude changes include pitch, roll and yaw; The swing condition of the vehicle is determined according to the rotation angle and the posture change.

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