Steering gear autonomous zero calibration control system and method

Abstract

The invention provides a steering gear autonomous zero calibration control system and a steering gear autonomous zero calibration control method. The steering gear autonomous zero calibration control system comprises a data acquisition module used for acquiring required bus message information; the vehicle mass calculation module is used for calculating the vehicle mass; the steering wheel angle calculation module is used for calculating a corresponding steering wheel sensor angle value; the tire pressure calculation module is used for receiving the tire pressure measured by the tire pressure sensor; the straight-line driving judgment module is used for judging whether the vehicle is in a straight-line driving state or not according to the wheel rotation angle obtained by the wheel rotation angle sensor in the steering controller; the zero angle control module is used for vehicle zero angle control calibration; and the data storage module is used for storing the data in the corresponding NVRAM after the vehicle learns new zero angle data. The problem that a steering wheel is not correct due to the fact that the electric power steering zero angle of the vehicle deviates from the zero position due to changes of the mass and the tire pressure of the vehicle is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile steering systems and relates to a steering gear autonomous zero position calibration control system and method. Background Art

[0002] With the rapid development of automobile intelligence and electrification, people have higher and higher requirements for the comfort and safety of automobiles. The steering system has also been continuously optimized and upgraded, gradually transitioning from hydraulic power steering to electric power steering to meet the needs of assisted driving, intelligent driving and unmanned driving. Electric power steering mainly installs an angle sensor on the steering wheel column to collect the hand force and angle of the steering wheel, and then drives the motor to output a certain torque through the steering controller control algorithm to drive the wheel to produce a certain angle to achieve the purpose of vehicle steering. Therefore, it is very important to ensure that the steering wheel is in the straight-ahead position when the tires of the vehicle are driving straight. The key to this design is to determine the zero position of the steering wheel angle.

[0003] In daily practical applications, vehicle mass (load) and tire pressure are two key factors affecting the zero position of the steering wheel. The zero position will have a "zero drift" phenomenon as the tire pressure and vehicle mass (load) change, that is, the steering wheel deviates from the zero position. For drivers of medium and light trucks, heavy trucks, etc., when the zero position of the steering wheel has a "zero drift", the steering wheel will be "not straight" when driving in a straight line, and the steering system's return function will be disturbed, resulting in the phenomenon of the steering wheel "returning to the right and deviating". At this time, the driver must find the corresponding service station to perform manual "zeroing" operation, which often brings a lot of trouble and inconvenience to truck drivers, and also affects the reliability and accuracy of the steering system, affecting the quality of the product. Therefore, it is urgent to design the zero angle calibration control technology of the automobile steering system. The existing zero angle zeroing method of the automobile steering system is usually that when the vehicle has a "zero drift", the driver needs to contact the main engine manufacturer, and the main engine manufacturer matches the driver with the corresponding service station for manual "zeroing" operation, which cannot achieve the vehicle's adaptive calibration, bringing unnecessary trouble to the majority of drivers. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide a steering gear autonomous zero position calibration control method and design an autonomous zeroing control system. The steering controller can "autonomously" calibrate the zero angle according to the vehicle mass and tire pressure to solve the problem that when the vehicle has "zero drift", the service station needs to perform manual "zeroing" operation and the vehicle cannot be "autonomously" calibrated.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] In one aspect, the present invention provides a steering gear autonomous zero position calibration control system, comprising:

[0007] Data acquisition module: used to obtain the required bus message information through the vehicle system CAN bus data, specifically to obtain the current gear position and gear ratio of the transmission through the message information sent by the transmission controller; to obtain the engine output torque from the message information sent by the engine controller; and to obtain the real-time data measured by each sensor of the vehicle;

[0008] Vehicle mass calculation module: used to calculate the vehicle mass according to the vehicle dynamics equation in the steering controller based on the data obtained by the data acquisition module;

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

[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: used in the steering controller to judge whether the vehicle is in a straight-line driving state according to 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 can be triggered to run, otherwise, the zero-angle control module will not run;

[0012] Zero angle control module: used for vehicle zero angle control calibration, and performs zero position control calibration according to the current tire pressure and the current vehicle mass to ensure that the vehicle will not cause "zero position drift" due to changes in tire pressure and vehicle mass;

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

[0014] On the other hand, the present invention provides a steering gear autonomous zero position calibration control method, which specifically includes the following steps:

[0015] Step 1: The mechanical installation of the power steering system is completed, and the vehicle's communication, electrical, braking, and lubrication systems are working properly, meeting the vehicle's driving conditions;

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

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

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

[0019] Step 5: Calculate the vehicle mass according to the vehicle dynamics equation in the steering controller;

[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 in a straight driving state according to the wheel rotation angle, and if so, proceeds to step 8; otherwise, re-executes step 7;

[0022] Step 8, when the vehicle is in a straight-line driving state, if the vehicle steering wheel is in the middle, execute step 10, if it is not in the middle, query the relationship table between the pre-test calibrated steering wheel zero angle, vehicle load and vehicle tire pressure to obtain the zero angle, and use the queried zero angle to replace the zero angle in the steering controller.

[0023] Step 9: Record the zero angle at this time and write it into 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: According to the characteristics of the NVRAM variable storage area, the key is disconnected and the zero angle is stored.

[0026] Furthermore, in step 5, the theoretical vehicle gross mass m is calculated by the following formula:

[0027]

[0028] Among them, T tq is the output torque at the engine crankshaft end, i g is the current gear ratio, i0 is the vehicle's main reducer ratio, θ is the ramp angle, η T is the mechanical efficiency of the transmission system, r is the wheel radius, m is the vehicle mass, g is the acceleration of gravity, f is the tire rolling resistance coefficient, C D is the air resistance coefficient, A is the windward projection area of ​​the vehicle, V a is the vehicle speed, and δ is the conversion factor of the vehicle's rotational mass into 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 at this time, that is, there is a problem that the steering wheel is not in the center when the vehicle is driving in a straight line, then the AngsoftDisp value in the steering controller is not 0, and there is a certain zero position deviation, then the zero angle needs to be recalculated, specifically: query the pre-calibrated relationship table, and use the queried zero angle Angzero instead of the original zero angle Angzero value, so that the AngsoftDisp value can be 0, and 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 vehicle driving through data interaction between modules such as a data acquisition module, a vehicle mass calculation module, a steering wheel angle calculation module, a tire pressure calculation module, a straight-line driving judgment module, a zero angle control module, and a data storage module, thereby avoiding the problem of steering wheel deviation, saving the driver's maintenance cost, and improving the performance of the steering gear product.

[0032] (2) The method of the present invention runs in a steering controller, which "autonomously" adjusts the zero angle of the steering wheel in real time 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, thereby ensuring that the steering wheel is always in the zero position, thus solving the problem that the zero angle of the vehicle's electric power steering deviates from the zero position and causes the steering wheel to be misaligned when the vehicle mass and tire pressure change.

[0033] (3) While ensuring that the vehicle has an accurate zero angle, the present invention also ensures the reliability, robustness and safety of the vehicle's power assist function, self-centering function and other functions, preventing the vehicle from returning to the center or deviating (causing the self-centering function to be abnormal), thus resolving the problem of truck drivers having to repair their vehicles due to the zero position problem of the steering wheel. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0035] Figure 2 Flowchart of the method of the present invention.

[0036] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0037] like Figure 1 As shown, the zero position calibration control system provided by the present invention comprises:

[0038] Data acquisition module: used to obtain the required bus message information through the vehicle system CAN bus data, specifically to obtain the current gear position and gear ratio of the transmission through the message information sent by the transmission controller; to obtain the engine output torque from the message information sent by the engine controller; and to obtain the real-time data measured by each sensor of the vehicle;

[0039] Vehicle mass calculation module: used to calculate the vehicle mass according to the vehicle dynamics equation based on the data obtained by the data acquisition module in the steering controller.

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

[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: used in the steering controller to judge 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 can be triggered to run, otherwise, the zero-angle control module will not run.

[0043] Zero angle control module: used for vehicle zero angle control calibration, performs zero position control calibration according to the current tire pressure and the current vehicle mass to ensure that the vehicle will not cause "zero position drift" due to changes in tire pressure and vehicle mass.

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

[0045] like Figure 2 As shown, the steering gear zero position calibration control method provided by the present 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 communication, electrical, braking and lubrication systems are working properly, meeting the vehicle driving conditions;

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

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

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

[0050] Step 5: Calculate the vehicle mass according to the vehicle dynamics equation in the steering controller;

[0051] Specifically, the vehicle dynamics equation is:

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

[0053] Among them, F t is the real-time driving force, F f is the rolling resistance, F i is the climbing resistance, F w is the air resistance, F a F is the acceleration resistance; t =T tq i g i0η T / r,F f = mgfcosθ, F i = mgsinθ, F w =0.0473C D AV a 2 , Among them, T tq is the output torque at the engine crankshaft end, i g is the current gear ratio, i0 is the vehicle main reducer ratio, η T is the mechanical efficiency of the transmission system, r is the wheel radius, m is the vehicle mass, g is the acceleration of gravity, f is the tire rolling resistance coefficient, C D is the air resistance coefficient, A is the windward projection area of ​​the vehicle, V a is the vehicle speed, δ is the conversion factor of the vehicle's rotational mass to translational mass; θ is the ramp angle.

[0054] The following formula can be obtained from the vehicle dynamics equation, and the theoretical vehicle total mass m can be calculated by the following formula:

[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 in a straight driving state according to the wheel rotation angle, and if so, proceeds to step 8; otherwise, re-executes step 7;

[0058] Step 8, when the vehicle is in a straight-line driving state, if the vehicle steering wheel is in the middle, execute step 10, if it is not in the middle, query the relationship table between the pre-test calibrated steering wheel zero angle, vehicle load and vehicle tire pressure to obtain the zero angle, and use the queried zero angle to replace the zero angle in the steering controller.

[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 at this time, that is, there is a problem that the steering wheel is not in the center when the vehicle is driving in a straight line, then the AngsoftDisp value in the steering controller is not 0, and there is a certain zero position deviation, then the zero angle needs to be recalculated, specifically: query relationship table 1, and use the queried zero angle Angzero instead of the original zero angle Angzero value, so that the AngsoftDisp value can be 0, and 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 the present invention, the zero position calibration of the vehicle is performed by the test calibration personnel who pre-adjust the vehicle to a combination of different vehicle masses and different tire pressures on the actual vehicle (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 middle position during the straight-line driving process, and the AngsoftDisp value in the steering controller is 0, so there will be no deviation problem. The relationship between the 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 items at the header are vehicle mass, the horizontal items at the header are tire pressure, and the data a1 to l8 in the table are the calibrated zero angles.

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

[0065] Step 9: Record the zero angle at this time and write it into 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: According to the characteristics of the NVRAM variable storage area, the zero angle is stored when the key is powered off, so as to ensure that the learning value of this power-on cycle can be directly used after the next power-on.

Claims

1. A steering gear autonomous zero position calibration control system, characterized in that: include: Data acquisition module: used to obtain the required bus message information through the vehicle system CAN bus data, specifically to obtain the current gear position and gear ratio of the transmission through the message information sent by the transmission controller; to obtain the engine output torque from the message information sent by the engine controller; and to obtain the real-time data measured by each sensor of the vehicle; Vehicle mass calculation module: used to calculate the vehicle mass according to the vehicle dynamics equation in the steering controller based on the data obtained by the data acquisition module; Steering wheel angle calculation module: used to calculate the corresponding steering wheel sensor angle value according to different steering wheel sensor types in the steering controller; Tire pressure calculation module: receives the tire pressure measured by the tire pressure sensor and inputs it to the steering controller; Straight-line driving judgment module: used in the steering controller to judge whether the vehicle is in a straight-line driving state according to 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 can be triggered to run, otherwise, the zero-angle control module will not run; Zero angle control module: used for vehicle zero angle control calibration, and performs zero position control calibration according to the current tire pressure and the current vehicle mass to ensure that the vehicle will not cause "zero position drift" due to changes in tire pressure and vehicle mass; Data storage module: used to save the data to the corresponding NVRAM after the vehicle learns new zero-angle data.

2. A steering gear autonomous zero position calibration control method, characterized in that: The specific steps include: Step 1: The mechanical installation of the power steering system is completed, and the vehicle's communication, electrical, braking, and lubrication systems are working properly, meeting the vehicle's driving conditions; Step 2: Power on the vehicle and start the engine; Step 3: The power steering system works and the vehicle enters driving mode; Step 4: Obtain the current gear position and transmission ratio of the transmission controller through the CAN bus data, and simultaneously collect the engine controller data to obtain the engine output torque; Step 5: Calculate the vehicle mass according to the vehicle dynamics equation in the steering controller; Step 6: The tire pressure sensor measures the tire pressure and inputs it to the steering controller; 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 in a straight driving state according to the wheel rotation angle, and if so, proceeds to step 8; otherwise, re-executes step 7; Step 8, when the vehicle is in a straight-line driving state, if the vehicle steering wheel is in the middle, execute step 10, if it is not in the middle, query the relationship table between the pre-test calibrated steering wheel zero angle, vehicle load and vehicle tire pressure to obtain the zero angle, and use the queried zero angle to replace the zero angle in the steering controller. Step 9: Record the zero angle at this time and write it into 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 disconnected and the zero angle is stored.

3. The steering gear autonomous zero position calibration control method according to claim 2, characterized in that: In step 5, the theoretical vehicle gross mass m is calculated by the following formula: Among them, T tq is the output torque at the engine crankshaft end, i g is the current gear ratio, i0 is the vehicle's main reducer ratio, θ is the ramp angle, η T is the mechanical efficiency of the transmission system, r is the wheel radius, m is the vehicle mass, g is the acceleration of gravity, f is the tire rolling resistance coefficient, C D is the air resistance coefficient, A is the windward projection area of ​​the vehicle, V a is the vehicle speed, and δ is the conversion factor of the vehicle's rotational mass into translational mass.

4. The steering gear autonomous zero position calibration control method according to claim 2, characterized in that: In step 8, when the vehicle is in a straight-line driving state, if the steering wheel is not in the correct zero position at this time, that is, there is a problem that the steering wheel is not in the center when the vehicle is driving in a straight line, then the AngsoftDisp value in the steering controller is not 0, and there is a certain zero position deviation, then the zero angle needs to be recalculated, specifically: query the pre-calibrated relationship table, and use the queried zero angle Angzero instead of the original zero angle Angzero value, so that the AngsoftDisp value can be 0, and 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.

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