A steering gear autonomous zero calibration control system and method

Abstract

The application provides a kind of steering gear autonomous zero calibration control system and method, system includes: data acquisition module: for obtaining the bus message information required;Vehicle mass calculation module: for calculating vehicle mass;Steering wheel angle calculation module: for calculating the corresponding steering wheel sensor angle value;Tire pressure calculation module: receiving tire pressure sensor measured tire pressure;Straight travel judging module: for in steering controller, according to the wheel rotation angle sensor obtained wheel rotation angle judges whether vehicle is in straight travel state;Zero angle control module: for vehicle zero angle control calibration;Data storage module: for when vehicle learns new zero angle data, save data to corresponding NVRAM.The application solves the problem that when vehicle zero angle deviates from zero due to changes in vehicle mass and tire pressure, causing the steering wheel to be incorrect.

Description

Technical Field

[0001] This invention belongs to the technical field of automotive steering systems, and relates to a steering gear autonomous zero-position calibration control system and method. Background Technology

[0002] With the rapid development of automotive intelligence and electrification, people have increasingly higher demands for vehicle comfort and safety. Steering systems are also constantly being optimized and upgraded, gradually transitioning from hydraulic power steering to electric power steering to meet the needs of assisted driving, intelligent driving, and autonomous driving. Electric power steering primarily involves installing angle sensors on the steering column to collect the amount of force applied to the steering wheel and the steering angle. Then, a steering controller algorithm drives the motor to output a certain torque, thereby causing the wheels to turn at a specific angle. Therefore, ensuring that the steering wheel is also in a straight position when the vehicle's tires are traveling straight is crucial. The key to this design lies in determining the zero point of the steering wheel angle.

[0003] In practical applications, vehicle weight (load capacity) and tire pressure are two key factors affecting the steering wheel's zero position. The zero position can exhibit "zero drift" due to changes in tire pressure and vehicle weight (load capacity), meaning the steering wheel deviates from its zero position. For drivers of light and heavy trucks, when the steering wheel experiences "zero drift," the steering wheel becomes "unaligned" during straight-line driving. Simultaneously, the steering system's return-to-center function is interfered with, causing the steering wheel to "return to center and then deviate again." In this situation, the driver must find a service station for manual "zeroing," which often causes considerable inconvenience and affects the reliability and accuracy of the steering system, impacting product quality. Therefore, there is an urgent need to design zero-angle calibration control technology for automotive steering systems. Currently, existing zero-angle calibration methods for automotive steering systems typically require the driver to contact the OEM (Original Equipment Manufacturer) after "zero drift" occurs. The OEM then arranges for a service station to perform manual "zeroing," failing to achieve adaptive calibration and causing unnecessary trouble for drivers. Summary of the Invention

[0004] Based on this, the purpose of this invention is to provide a steering gear autonomous zero-position calibration control method. An autonomous zero-calibration control system is designed, which allows the steering controller to "autonomously" calibrate the zero angle according to the vehicle mass and tire pressure. This solves the problem that when a vehicle experiences "zero drift," a service station is required to manually "calibrate" the zero position, thus preventing the vehicle from achieving "autonomous" calibration.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] On one hand, the present invention provides an autonomous zero-position calibration control system for a steering gear, comprising:

[0007] Data acquisition module: used to acquire the required bus message information through the vehicle system CAN bus data, including the current gear and gear ratio of the transmission from the message information sent by the transmission controller; the engine output torque from the message information sent by the engine controller; and real-time data measured by various vehicle sensors.

[0008] Vehicle mass calculation module: used in the steering controller to calculate the vehicle mass based on the data obtained from the data acquisition module and the vehicle dynamics equations;

[0009] Steering wheel angle calculation module: used to calculate the corresponding steering wheel sensor angle value in the steering controller according to different steering wheel sensor types;

[0010] Tire pressure calculation module: Receives the tire pressure measured by the tire pressure sensor and inputs it to the steering controller;

[0011] Straight-line driving judgment module: In the steering controller, it is used to determine whether the vehicle is in a straight-line driving state based on the wheel rotation angle obtained by the wheel rotation angle sensor. When the vehicle is in a straight-line driving state, the zero-angle control module is triggered to run; otherwise, the zero-angle control module does not run.

[0012] Zero-angle control module: used for vehicle zero-angle control calibration. It performs zero-position control calibration based on the current tire pressure and current vehicle weight to ensure that the vehicle will not experience "zero-position drift" due to changes in tire pressure and vehicle weight.

[0013] Data storage module: Used to save the new zero-angle data to the corresponding NVRAM after the vehicle learns it.

[0014] On the other hand, the present invention provides a steering gear autonomous zero-position calibration control method, which is based on the steering gear autonomous zero-position calibration control system of the present invention described above, and includes the following steps:

[0015] Step 1: The power steering system is mechanically installed and the vehicle's communication, electrical, braking, and lubrication systems are functioning normally, meeting the vehicle's driving requirements;

[0016] Step 2: Power on the vehicle and start the engine;

[0017] Step 3: The power steering system engages, and the vehicle enters driving mode;

[0018] Step 4: Obtain the current gear and gear ratio of the transmission through CAN bus data, and at the same time collect engine controller data to obtain the engine output torque;

[0019] Step 5: Calculate the vehicle mass in the steering controller based on the vehicle dynamics equations;

[0020] Step 6: The tire pressure sensor measures the tire pressure and inputs it to the steering controller;

[0021] Step 7: The wheel angle sensor collects the wheel rotation angle and inputs it into the steering controller; the steering controller determines whether the vehicle is currently driving straight based on the wheel rotation angle. If yes, proceed to step 8; otherwise, repeat step 7.

[0022] Step 8: When the vehicle is driving in a straight line, if the steering wheel is in the center, proceed to step 10. If it is not in the center, look up the relationship table between the zero angle of the steering wheel, the vehicle load, and the vehicle tire pressure as determined by the pre-test calibration to obtain the zero angle, and replace the zero angle in the steering controller with the zero angle found.

[0023] Step 9: Record the zero angle at this moment and write it into the NVRAM. At this time, the steering wheel angle display value is equal to the difference between the steering wheel TAS sensor angle and the zero angle.

[0024] AngsoftDisp=AngTas-Angzero;

[0025] Step 10: Based on the characteristics of the NVRAM variable storage area, the key is powered off and the zero angle is stored.

[0026] Furthermore, in step 5, the vehicle mass is calculated using the following formula. m :

[0027]

[0028] in, T tq This refers to the output torque at the crankshaft end of the engine. i g The gear ratio of the current gear. i 0 represents the speed ratio of the vehicle's main reducer. θ For the slope angle, η r For the mechanical efficiency of the transmission system, r For the wheel radius, m For vehicle quality, g It is the acceleration due to gravity. f This is the tire rolling resistance coefficient. C D The air drag coefficient, A This refers to the windward projected area of ​​the vehicle. V a For vehicle speed, The conversion factor for converting the vehicle's rotational mass to its translational mass.

[0029] Furthermore, in step 8, when the vehicle is in a straight-line driving state, if the steering wheel is not in the correct zero position, the AngsoftDisp value in the steering controller will not be 0, indicating a zero position deviation. In this case, the zero angle needs to be recalculated. Specifically, a pre-calibrated relation table is consulted, and the queried zero angle Angzero is used to replace the original zero angle Angzero value, thereby making the AngsoftDisp value 0. At this time, the vehicle steering wheel adapts to the center position to ensure that the steering wheel is in the center when the vehicle is in a straight-line driving state.

[0030] Compared with the prior art, the present invention has the following technical effects:

[0031] (1) The present invention can calculate the accurate current zero angle of the vehicle based on real-time data during the vehicle's driving process through data interaction between various modules such as data acquisition module, vehicle mass calculation module, steering wheel angle calculation module, tire pressure calculation module, straight driving judgment module, zero angle control module, and data storage module, thereby avoiding the problem of steering wheel deviation, saving the driver's maintenance costs, and improving the performance of the steering gear product.

[0032] (2) The method of the present invention operates in the steering controller. The steering controller adjusts the zero angle of the steering wheel in real time "autonomously" according to the changes in vehicle mass and tire pressure through the zero angle calibration control algorithm inside the software, and stores the adjusted zero angle of the steering wheel, ensuring that the steering wheel is always in the zero position. This solves the problem that when the vehicle mass and tire pressure change, the zero angle of the electric power steering of the vehicle deviates from the zero position, causing the steering wheel to be crooked.

[0033] (3) This invention ensures that the vehicle has an accurate zero angle, while also ensuring the reliability, robustness and safety of the vehicle's power steering function, return-to-center function and other functions, preventing the vehicle from going back to center or deviating (causing the return-to-center function to malfunction), and solving the problem of truck drivers having to repair the vehicle due to the zero position of the steering wheel. Attached Figure Description

[0034] Figure 1 This is a structural diagram of the system of the present invention;

[0035] Figure 2 This is a flowchart of the method of the present invention.

[0036] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0037] like Figure 1 As shown, the zero-point calibration control system provided by this invention includes:

[0038] Data acquisition module: used to acquire the required bus message information through the vehicle system CAN bus data, including the current gear and gear ratio of the transmission from the message information sent by the transmission controller; the engine output torque from the message information sent by the engine controller; and real-time data measured by various vehicle sensors.

[0039] Vehicle mass calculation module: Used in the steering controller to calculate the vehicle mass based on the data obtained from the data acquisition module and the vehicle dynamics equation.

[0040] Steering wheel angle calculation module: Used in the steering controller to calculate the corresponding steering wheel sensor angle value according to different steering wheel sensor types.

[0041] Tire pressure calculation module: Receives the tire pressure measured by the tire pressure sensor and inputs it to the steering controller.

[0042] Straight-line driving judgment module: In the steering controller, it is used to determine whether the vehicle is in a straight-line driving state based on the wheel rotation angle obtained by the wheel rotation angle sensor. When the vehicle is in a straight-line driving state, the zero-angle control module is triggered to run; otherwise, the zero-angle control module does not run.

[0043] Zero-angle control module: used for vehicle zero-angle control calibration. It performs zero-position control calibration based on the current tire pressure and current vehicle weight to ensure that the vehicle will not experience "zero-position drift" due to changes in tire pressure and vehicle weight.

[0044] Data storage module: When the vehicle learns new zero-angle data, it saves the data to the corresponding NVRAM to ensure that the learned value of this power-on cycle can be used directly after the next power-on.

[0045] like Figure 2 As shown, the steering gear zero-position calibration control method provided by this invention, which is based on the steering gear autonomous zero-position calibration control system of this invention, specifically includes the following steps:

[0046] Step 1: The power steering system (including hydraulic power steering system and electric power steering system) is mechanically installed, and the vehicle's communication, electrical, braking and lubrication systems are working normally and meet the vehicle's driving conditions;

[0047] Step 2: Power on the vehicle and start the engine;

[0048] Step 3: The power steering system engages, and the vehicle enters driving mode;

[0049] Step 4: Obtain the current gear and gear ratio of the transmission through CAN bus data, and at the same time collect engine controller data to obtain the engine output torque;

[0050] Step 5: Calculate the vehicle mass in the steering controller based on the vehicle dynamics equations;

[0051] Specifically, the vehicle dynamics equations are:

[0052] F t = F f + F i + F w + F a ;

[0053] in, F t For real-time driving force, F f For rolling resistance, F i For climbing resistance, F w For air resistance, F a To increase resistance; , , , , ;in, T tq This refers to the output torque at the crankshaft end of the engine. i g The gear ratio of the current gear. i 0 represents the speed ratio of the vehicle's main reducer. For the mechanical efficiency of the transmission system, r For the wheel radius, m For vehicle quality, g It is the acceleration due to gravity. f This is the tire rolling resistance coefficient. C D The air drag coefficient, A This refers to the windward projected area of ​​the vehicle. V a For vehicle speed, A conversion factor for converting the vehicle's rotational mass to its translational mass; The slope angle.

[0054] The following formula can be obtained from the vehicle dynamics equations, and the vehicle mass can be calculated using the following formula. m :

[0055] .

[0056] Step 6: The tire pressure sensor measures the tire pressure and inputs it to the steering controller.

[0057] Step 7: The wheel angle sensor collects the wheel rotation angle and inputs it into the steering controller; the steering controller determines whether the vehicle is currently driving straight based on the wheel rotation angle. If yes, proceed to step 8; otherwise, repeat step 7.

[0058] Step 8: When the vehicle is driving in a straight line, if the steering wheel is in the center, proceed to step 10. If it is not in the center, look up the relationship table between the zero angle of the steering wheel, the vehicle load, and the vehicle tire pressure as determined by the pre-test calibration to obtain the zero angle, and replace the zero angle in the steering controller with the zero angle found.

[0059] Specifically, in step 8, when the vehicle is in a straight-line driving state, if the steering wheel is not in the correct zero position, the AngsoftDisp value in the steering controller is not 0, indicating a zero position deviation. Therefore, the zero angle needs to be recalculated. Specifically, the relationship table 1 is consulted, and the queried zero angle Angzero is used to replace the original zero angle Angzero value, so that the AngsoftDisp value is 0. At this time, the vehicle steering wheel adapts to the center position to ensure that the steering wheel is in the center when the vehicle is in a straight-line driving state.

[0060] In this invention, the zero-point calibration of the vehicle is pre-adjusted by the test calibration personnel on the actual vehicle to different combinations of vehicle mass and different tire pressure (the specific combinations are shown in Table 1 below), thereby calibrating the corresponding zero angle to ensure that the vehicle steering wheel is in the center position during the straight driving process, the AngsoftDisp value in the steering controller is 0, and there will be no deviation problem. The relationship between vehicle tire pressure, vehicle mass and zero angle is shown in Table 1.

[0061] Table 1. Relationship between wheel rotation angle, vehicle mass, and zero angle

[0062]

[0063] In Table 1, the column headings are for vehicle weight, the horizontal column headings are for tire pressure, and the data a1 to l8 in the table are the calibrated zero angles.

[0064] In this invention, when the vehicle is in a straight-line driving state, the steering controller determines the current steering wheel zero position according to the current vehicle mass and tire pressure lookup table 1 (intermediate data not in the table can be filled in by linear interpolation).

[0065] Step 9: Record the zero angle at this time and write it into the NVRAM. At this time, the steering wheel angle display value is equal to the difference between the steering wheel TAS sensor angle and the zero angle.

[0066] AngsoftDisp=AngTas-Angzero;

[0067] Step 10: Based on the characteristics of the NVRAM variable storage area, store the zero angle when the key is turned off. This ensures that the learned value of this power-on cycle can be used directly after the next power-on.

Claims

1. A steering gear autonomous zero calibration control system, characterized by, Comprise: Data acquisition module: for obtaining the required bus message information through the vehicle system CAN bus data, wherein the message information sent by the transmission controller obtains the current gear of the transmission and the transmission speed ratio; the message information sent by the engine controller obtains the engine output torque; and the real-time measured data of each sensor of the vehicle is obtained; Vehicle mass calculation module: for calculating the vehicle mass in the steering controller according to the data obtained by the data acquisition module according to the vehicle dynamics equation; Steering wheel angle calculation module: for calculating the corresponding steering wheel sensor angle value in the steering controller according to different steering wheel sensor types; Tire pressure calculation module: receiving the tire pressure measured by the tire pressure sensor and inputting to the steering controller; Straight driving judgment module: for judging whether the vehicle is in a straight driving state according to the wheel rotation angle obtained by the wheel rotation angle sensor in the steering controller, triggering the zero angle control module to run when the vehicle is in a straight driving state, otherwise, the zero angle control module does not run; Zero angle control module: for vehicle zero angle control calibration, zero position control calibration is performed according to the current tire pressure and the current vehicle mass to ensure that the vehicle will not cause "zero drift" due to changes in tire pressure and vehicle mass; Data storage module: for saving the data to the corresponding NVRAM when the vehicle learns new zero angle data.

2. A method for autonomous zero calibration control of a steering gear, characterized in that The method based on the steering self-zero calibration control system of claim 1, comprising the following steps: Step 1: the mechanical installation of the power steering system is completed, and the communication, electrical, braking, and lubrication systems of the whole vehicle are working normally, meeting the vehicle driving conditions; Step 2: the vehicle is powered on and the engine is ignited; Step 3: the power steering system is working and the vehicle enters the driving mode; Step 4: the current gear of the transmission and the transmission speed ratio are obtained through CAN bus data, and the engine output torque is obtained by collecting the engine controller data; Step 5: the vehicle mass is calculated in the steering controller according to the vehicle dynamics equation; Step 6: the tire pressure measured by the tire pressure sensor is input to the steering controller; Step 7: the wheel angle sensor collects the wheel rotation angle and inputs it to the steering controller; the steering controller judges whether the vehicle is currently in a straight driving state according to the wheel rotation angle, and if so, it proceeds to step 8; otherwise, it re-executes step 7; Step 8: when the vehicle is in a straight driving state, if the steering wheel is in the middle, step 10 is executed, if not, the relationship table between the pre-test calibrated steering wheel zero angle, vehicle load and vehicle tire pressure is queried to obtain the zero angle, and the queried zero angle is used to replace the zero angle in the steering controller; Step 9: record the zero angle at this time and write it into the NVRAM, at this time the steering wheel angle display value is equal to the difference between the steering wheel TAS sensor angle and the zero angle: AngsoftDisp=AngTas-Angzero; Step 10: according to the characteristics of the NVRAM variable storage area, the key is powered off and the zero angle is stored.

3. The method of claim 2, wherein, In step 5, the vehicle mass is calculated by the following formula m : wherein, T tq is the output torque of the engine crankshaft end, i g is the current gear ratio, i 0 is the vehicle main reducer ratio, θ is the ramp angle, η T is the transmission mechanical efficiency and, r is the wheel radius, m is the vehicle mass, g is the gravitational acceleration, f is the tire rolling resistance coefficient, C D is the air resistance coefficient, A is the vehicle frontal area, V a is the vehicle speed, is the conversion factor of the vehicle rotational mass to the translational mass.

4. The method of claim 2, wherein, In step 8, when the vehicle is in straight driving state, if the steering wheel is not in the correct zero position at this time, the AngsoftDisp value in the steering controller is not 0, there is a zero position deviation, the zero angle needs to be recalculated, wherein the zero angle Angzero obtained by querying the pre-marked relationship table is used to replace the original zero angle Angzero value, so that the AngsoftDisp value is 0, at this time the vehicle steering wheel is self-adapted to the center position, and it is ensured that the vehicle is in straight driving state and the steering wheel is in the center position.

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