A calculation method based on EPS angle following control

Abstract

The present application relates to the technical fields of electric power steering, in particular to a calculation method based on EPS angle following control, including target angular velocity calculation method and target torque calculation method, compared with the prior art, the present application solves the problem of slow response time and response sticking under small angle and small rotating speed, realizes the EPS angle following performance requirement in the whole vehicle speed range, and simultaneously realizes the technical effects of non-dithering at low vehicle speed, timely following at high vehicle speed and reducing dithering on uneven road surface.

Description

Technical Field

[0001] This invention relates to the field of electric power steering technology, specifically a calculation method based on EPS angle following control. Background Technology

[0002] With the development of intelligent driving, people have increasingly higher requirements for driver assistance functions, including lane centering control and lane departure control. The development of these technologies all require steering actuators, such as EPS systems, to execute steering commands. Therefore, control strategies that enable the steering angle to quickly and accurately follow the target angle sent by the host computer are of great significance.

[0003] Due to the complex and ever-changing driving environment, many factors affect the cornering and following control performance, including vehicle speed and road surface.

[0004] The requirements for steering angle following performance vary at different vehicle speeds. At low speeds, large-angle, high-revving maneuvers are often possible, such as emergency maneuvers, U-turns, and lane changes; however, large-angle, high-revving maneuvers are generally not permitted at high speeds. Therefore, the maximum permissible angle and revving speed also differ at different vehicle speeds. Because the basic power assist of EPS is often greater at low speeds than at high speeds, the performance at different speeds often differs. At low speeds, excessive correction and vibration are more likely to occur, while at high speeds, following delays are more likely to occur.

[0005] Different road surface excitations can cause torsion bar deformation, which in turn affects the stability of angle control. This usually manifests as severe EPS vibration when driving over bumpy roads.

[0006] Besides the influence of vehicle speed and road surface, due to the large inertia of the motor, the control performance is often poor when adjusting with a small angle difference because the basic assist is relatively small. This usually manifests as a slow response time and easy jamming during the response process.

[0007] Therefore, it is necessary to design a calculation method based on EPS angle following control to solve the problems of slow response time and sluggish response at small angles and low speeds. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a calculation method based on EPS angle following control to solve the problems of slow response time and sluggish response at small angles and small speeds.

[0009] To achieve the above objectives, this invention provides a calculation method based on EPS angle following control, including a target angular velocity calculation method and a target torque calculation method. The target angular velocity calculation includes the following steps: Step 1, the EPS control unit acquires the target angle AngReq and activation request ActReq sent by the advanced driver assistance system, acquires the current EPS angle CurrentAng, and acquires the current vehicle speed; Step 2, the target angle AngReq is processed to obtain the target angle TargetAng; Step 3, the angle difference DeltaAng is calculated. Step 4: Perform real-vehicle testing based on the angle difference DeltaAng and the current vehicle speed to determine the target angular velocity closed-loop control parameter rule base; Step 5: Determine the small angle boundary value SmallAngComp that needs to be compensated through real-vehicle testing; Step 6: Perform real-vehicle testing based on the angle difference DeltaAng and the current vehicle speed to determine the small angle gain Ps parameter rule base; Step 7: Determine whether the angle difference DeltaAng is less than the small angle boundary value SmallAngComp. If so, calculate the target angular velocity TargetAngSpd = the calculated value of the angle difference DeltaAng obtained through closed-loop control + the small angle gain Ps; if not, calculate the target angular velocity TargetAngSpd = the calculated value of the angle difference DeltaAng obtained through closed-loop control.

[0010] The target torque calculation includes the following steps: Step 8, the EPS control unit obtains the activation request ActReq and torque limit TorqLim sent by the advanced driver assistance system, obtains the current EPS angle CurrentAng, obtains the current vehicle speed, and the steering wheel angular acceleration aRotAcceleration; Step 9, the EPS control unit determines whether the activation request ActReq is activated. If not, the target torque is calculated and output as 0. If so, the active return to center is turned off, and the process continues to Step 10; Step 10, the target angular velocity TargetAngSpd is processed to obtain the filtered target angular velocity TargetAngSpdFilt, and the actual angular velocity CurrentAngSpd is filtered to obtain the filtered actual angular velocity CurrentAngSpdFilt; Step 11, the angular velocity difference DeltaAngSpd = Step 12: Perform real-vehicle testing based on the angular velocity difference DeltaAngSpd and the current vehicle speed to determine the target torque closed-loop control parameter rule base; Step 13: Determine the road conditions based on the steering angle acceleration change frequency, and determine the target torque reduction coefficient Pc based on the duration of the angular acceleration change frequency, and perform real-vehicle testing to determine the target torque reduction coefficient Pc parameter rule base; Step 14: Determine whether the angular acceleration change frequency is greater than a fixed value f. If so, calculate the target torque TargetTorq = Angular velocity difference DeltaAngSpd calculated through closed-loop control × target torque reduction coefficient Pc; if not, calculate the target torque TargetTorq = Angular velocity difference DeltaAngSpd calculated through closed-loop control; Step 15: Perform signal processing on the target torque TargetTorq to obtain the final target torque TargetTorqFilt.

[0011] The signal processing for the target angle AngReq, the target angular velocity TargetAngSpd, and the target torque TargetTorq includes amplitude limiting and filtering.

[0012] Step 4 includes the following steps: Step 4a, under the vehicle debugging condition, at different vehicle speeds, a set of closed-loop control parameters are preset according to different angle differences DeltaAng, and the target angular velocity TargetAngSpd is obtained through closed-loop control; Step 4b, according to the value of the target angular velocity TargetAngSpd, the preset closed-loop parameter values ​​are corrected until the obtained target angular velocity TargetAngSpd meets the performance requirements; Step 4c, the corrected closed-loop parameter values ​​are recorded and stored in the target angular velocity closed-loop control parameter rule base.

[0013] Step 5 includes the following steps: Step 5a, vehicle debugging condition, at different vehicle speeds, the advanced driver assistance system sends different target angles AngReq, and observes the angle difference DeltaAng between the current angle CurrentAng and the target angle AngReq of EPS and the response time; Step 5b, according to performance requirements, set the small angle boundary value SmallAngComp.

[0014] Step 6 includes the following steps: Step 6a, under the vehicle debugging condition, obtain the small angle boundary values ​​that need to be compensated at different vehicle speeds; Step 6b, set a set of difference lookup tables, and obtain the target angular velocity gain value by looking up the table through the angle difference DeltaAng; Step 6c, correct the preset target angular velocity gain value according to the actual target angular velocity value until the obtained target angular velocity meets the performance requirements; Step 6d, record the corrected target angular velocity gain value and store it in the small angle gain Ps parameter rule library.

[0015] Step 12 includes the following steps: Step 12a, under vehicle debugging conditions, at different vehicle speeds, a set of closed-loop control parameters are preset according to different angular velocity differences DeltaAngSpd, and the target torque TargetTorq is obtained through closed-loop control; Step 12b, according to the target torque TargetTorq, the motor drives the steering wheel to rotate the corresponding angle; Step 12c, according to the following situation of the current angle CurrentAng and the target angle TargetAng, the preset closed-loop parameter values ​​are corrected until the current angle CurrentAng meets the performance requirements; Step 12d, the corrected closed-loop parameter values ​​are recorded and stored in the target torque closed-loop control parameter rule library.

[0016] The aforementioned tracking conditions include performance requirements for response time, steady-state error, and overshoot.

[0017] Step 13 includes the following steps: Step 13a, calculate the number of times n, during the time deltT, the detected angular acceleration value alternates between being greater than a and then less than -a, or being less than a and then greater than a; Step 13b, calculate the angular acceleration change frequency = n / deltT. If the angular acceleration change frequency = 0, the road surface condition is normal; if the angular acceleration change frequency > 0, the road surface condition is bumpy; Step 13c, if the angular acceleration change frequency > F, and the duration of the steering angular acceleration change frequency is < t1, then the target torque reduction coefficient Pc = Pc1; if the angular acceleration change frequency > F, and the duration of the steering angular acceleration change frequency is > t1 and < t2, then the target torque reduction coefficient Pc = Pc2; if the angular acceleration change frequency > F, and the duration of the steering angular acceleration change frequency is > t2 and < t3, then the target torque reduction coefficient Pc = Pc3.

[0018] The values ​​deltT, a, F, t1, Pc1, t2, Pc2, t3, and Pc3 mentioned are all calibration values ​​determined through actual vehicle testing.

[0019] Compared with existing technologies, this invention solves the problems of slow response time and sluggish response at small angles and low speeds, and achieves the EPS steering angle following performance requirements across the entire vehicle speed range. At the same time, it can achieve the technical effects of no shaking at low speeds, timely following at high speeds, and reduced shaking on uneven road surfaces. Attached Figure Description

[0020] Figure 1 This is a flowchart of the target angular velocity calculation method of the present invention.

[0021] Figure 2 This is a flowchart of the target torque calculation method of the present invention. Implementation

[0022] The present invention will now be further described with reference to the accompanying drawings.

[0023] This invention is a calculation method based on EPS angle following control, including a target angular velocity calculation method and a target torque calculation method.

[0024] See Figure 1 The calculation of the target angular velocity includes the following steps:

[0025] Step 1: The EPS control unit obtains the target angle AngReq and activation request ActReq sent by the advanced driver assistance system through CAN network message signal transmission, obtains the current EPS angle CurrentAng, and obtains the current vehicle speed.

[0026] Step 2: Perform signal processing on the target angle AngReq to obtain the target angle TargetAng. Signal processing on the target angle AngReq includes amplitude limiting and filtering.

[0027] Step 3, calculate the angle difference DeltaAng = TargetAng - CurrentAng.

[0028] Step 4: Conduct actual vehicle testing based on the angle difference DeltaAng and the current vehicle speed to determine the target angular velocity closed-loop control parameter rule base, as follows:

[0029] Step 4a: Under the vehicle debugging condition, at different vehicle speeds, a set of closed-loop control parameters are preset according to different angle differences DeltaAng, and the target angular velocity TargetAngSpd is obtained through closed-loop control; Step 4b: Based on the value of the target angular velocity TargetAngSpd, the preset closed-loop parameter values ​​are corrected until the obtained target angular velocity TargetAngSpd meets the performance requirements. The performance requirements can be adjusted according to actual needs, such as the target angular velocity TargetAngSpd being a smooth curve; Step 4c: The corrected closed-loop parameter values ​​are recorded and stored in the target angular velocity closed-loop control parameter rule base.

[0030] Common closed-loop control methods include PID control. The closed-loop control parameters are P, I, and D parameters, each of which is an array of parameters related to the current vehicle speed and the angle difference DeltaAng.

[0031] Step 5: Determine the small angle boundary value SmallAngComp that needs to be compensated through actual vehicle testing, as follows:

[0032] Step 5a: Under vehicle testing conditions, at different vehicle speeds, the advanced driver assistance system sends different target angles AngReq. The angle difference DeltaAng between the current angle CurrentAng and the target angle AngReq in the EPS system is observed, along with the response time. Step 5b: Based on performance requirements, a small angle boundary value, SmallAngComp, is set. For example, if the performance requirement is a response time of T, then an angle difference with a response time greater than T is found in the data, and the response time is reduced through compensation.

[0033] Step 6: Based on the angle difference DeltaAng and the current vehicle speed, conduct actual vehicle testing to determine the small angle gain Ps parameter rule base, as follows:

[0034] Step 6a: Under the vehicle debugging condition, obtain the small angle boundary values ​​that need to be compensated at different vehicle speeds; Step 6b: Set up a set of difference lookup tables, and obtain the target angular velocity gain value by looking up the table through the angle difference DeltaAng; for example, if the small angle boundary value that needs to be compensated is A degrees based on different vehicle speeds, then set the X-axis of the lookup table to the angle difference [X0, X1, X2...A], and the Y-axis of the lookup table to the target angular velocity gain value corresponding to the angle difference DeltaAng; Step 6c: Correct the preset target angular velocity gain value according to the actual target angular velocity value until the obtained target angular velocity meets the performance requirements; Step 6d: Record the corrected target angular velocity gain value and store it in the small angle gain Ps parameter rule library.

[0035] Step 7: Determine if the angle difference DeltaAng is less than the small angle boundary value SmallAngComp. If so, calculate the target angular velocity TargetAngSpd = the calculated value of the angle difference DeltaAng obtained through closed-loop control + the small angle gain Ps. If not, calculate the target angular velocity: TargetAngSpd = the calculated value of the angle difference DeltaAng obtained through closed-loop control. The calculated value of the angle difference DeltaAng obtained through closed-loop control refers to the target angular velocity obtained through angle difference closed-loop control, for example, the target angular velocity is obtained through PID control of the angle difference.

[0036] The algorithms involved in steps 2 to 7, such as amplitude limiting, filtering, angle difference calculation, PID control, and logic judgment, are all modeled using Matlab / simulink, and the generated code is written into the EPS controller to realize signal logic operations.

[0037] See Figure 2 The target torque calculation includes the following steps: Step 8, the EPS control unit obtains the activation request ActReq and torque limit TorqLim sent by the advanced driver assistance system through CAN network message signal transmission, obtains the current EPS angle CurrentAng, obtains the current vehicle speed, and obtains the steering wheel angle acceleration aRotAcceleration.

[0038] Step 9: The EPS control unit determines whether the activation request ActReq is activated. If not, it calculates the target torque output to 0. If so, it disables active return to center and continues to step 10.

[0039] Step 10: Perform signal processing on the target angular velocity TargetAngSpd to obtain the filtered target angular velocity TargetAngSpdFilt. Signal processing on TargetAngSpd includes amplitude limiting and filtering. Then, filter the actual angular velocity CurrentAngSpd to obtain the filtered actual angular velocity CurrentAngSpdFilt.

[0040] Step 11, calculate the angular velocity difference DeltaAngSpd = TargetAngSpdFilt - CurrentAngSpdFilt.

[0041] Step 12: Based on the angular velocity difference DeltaAngSpd and the current vehicle speed, conduct actual vehicle testing to determine the target torque closed-loop control parameter rule base, as follows:

[0042] Step 12a: Under vehicle debugging conditions, at different vehicle speeds, a set of closed-loop control parameters are preset based on different angular velocity differences DeltaAngSpd, and the target torque TargetTorq is obtained through closed-loop control; Step 12b: Based on the target torque TargetTorq, the motor drives the steering wheel to rotate the corresponding angle; Step 12c: Based on the following relationship between the current angle CurrentAng and the target angle TargetAng, including response time, steady-state error, and overshoot performance requirements, the preset closed-loop parameter values ​​are corrected until the obtained current angle CurrentAng meets the performance requirements; Step 12d: The corrected closed-loop parameter values ​​are recorded and stored in the target torque closed-loop control parameter rule library.

[0043] Step 13: Determine road conditions based on the frequency of change in steering angle acceleration, and determine the target torque reduction coefficient Pc based on the duration of the frequency of change in steering angle acceleration. Conduct actual vehicle testing to determine the parameter rule base for the target torque reduction coefficient Pc, as detailed below:

[0044] Step 13a: Calculate the number of times n, during the time interval deltT, the detected angular acceleration value alternates between being greater than a and then less than -a, or being less than a and then greater than a. Step 13b: Calculate the angular acceleration change frequency = n / deltT. If the angular acceleration change frequency = 0, the road surface condition is normal; if the angular acceleration change frequency > 0, the road surface condition is bumpy. Step 13c: The angular acceleration begins to weaken when the change frequency exceeds a certain fixed value F. The longer the angular acceleration change frequency exceeds F, the greater the weakening effect. If the angular acceleration change frequency > F, and the duration of the steering angular acceleration change frequency is < t1, then the target torque weakening coefficient Pc = Pc1; if the angular acceleration change frequency > F, and the duration of the steering angular acceleration change frequency is > t1 and < t2, then the target torque weakening coefficient Pc = Pc2; if the angular acceleration change frequency > F, and the duration of the steering angular acceleration change frequency is > t2 and < t3, then the target torque weakening coefficient Pc = Pc3.

[0045] Among them, deltT, a, F, t1, Pc1, t2, Pc2, t3, and Pc3 are all calibration values ​​determined through actual vehicle testing.

[0046] Step 14: Determine if the frequency of angular acceleration change is greater than a fixed value f. If yes, calculate the target torque TargetTorq = Angular velocity difference DeltaAngSpd (calculated through closed-loop control) × Target torque reduction coefficient Pc. If not, calculate the target torque TargetTorq = Angular velocity difference DeltaAngSpd (calculated through closed-loop control). The Angular velocity difference DeltaAngSpd (calculated through closed-loop control) refers to the target torque obtained through angular velocity difference closed-loop control, for example, the target torque obtained through PID control of the angular velocity difference.

[0047] Step 15: Perform signal processing on the target torque TargetTorq to obtain the final target torque TargetTorqFilt. Signal processing on the target torque TargetTorq includes amplitude limiting and filtering.

[0048] The algorithms involved in steps 9-15, such as amplitude limiting, filtering, angle difference calculation, PID control, and logic judgment, are all modeled using Matlab / simulink, and the generated code is written into the EPS controller to realize signal logic operations.

[0049] Real vehicle test results: During the real vehicle test of Project A, it was found that the longest response time for actual angle response requests was when requesting angle reversal at small angles. Long response times would result in lag.

[0050] The table below shows the parameter rule base for the small angle gain Ps at different vehicle speeds with angle differences ranging from 0 to 0.9.

[0051] Real-vehicle testing showed that at a speed of 30 km / h, without the small-angle gain Ps strategy, the original vehicle's reversing response time was 300 ms. With the small-angle gain Ps strategy applied at the same speed, the original vehicle's reversing response time was reduced to 180 ms, indicating an improvement in response time. This demonstrates that the small-angle gain Ps strategy effectively addresses the issue of slow response time and sluggishness at small angles and low speeds.

[0052] This invention optimizes control within a classic closed-loop control algorithm. In the position loop, small-angle control based on the difference between the target angle and the current angle is added to adjust the end-point following performance and small-angle response. In the speed loop, closed-loop control parameters are output according to certain rules, and torque adjustments are made considering factors such as vehicle speed and road surface. This achieves EPS steering angle following performance requirements across the entire vehicle speed range, while maintaining smooth performance at low speeds and timely following at high speeds. It also ensures normal response time and a smooth response process at small angles and low speeds, and reduces EPS system vibration on bumpy roads.

Claims

1. A calculation method based on EPS angle following control, characterized in that: This includes methods for calculating target angular velocity and target torque. The target angular velocity calculation includes the following steps: Step 1, the EPS control unit acquires the target angle AngReq and activation request ActReq sent by the advanced driver assistance system, acquires the current EPS angle CurrentAng, and acquires the current vehicle speed; Step 2, the target angle AngReq is processed to obtain the target angle TargetAng; Step 3, the angle difference DeltaAng is calculated. Step 4: Perform real-vehicle testing based on the angle difference DeltaAng and the current vehicle speed to determine the target angular velocity closed-loop control parameter rule base; Step 5: Determine the small angle boundary value SmallAngComp that needs to be compensated through real-vehicle testing; Step 6: Perform real-vehicle testing based on the angle difference DeltaAng and the current vehicle speed to determine the small angle gain Ps parameter rule base; Step 7: Determine whether the angle difference DeltaAng is less than the small angle boundary value SmallAngComp. If so, calculate the target angular velocity TargetAngSpd = the calculated value of the angle difference DeltaAng obtained through closed-loop control + the small angle gain Ps; if not, calculate the target angular velocity TargetAngSpd = the calculated value of the angle difference DeltaAng obtained through closed-loop control. The target torque calculation includes the following steps: Step 8, the EPS control unit obtains the activation request ActReq and torque limit TorqLim sent by the advanced driver assistance system, obtains the current EPS angle CurrentAng, obtains the current vehicle speed, and the steering wheel angular acceleration aRotAcceleration; Step 9, the EPS control unit determines whether the activation request ActReq is activated. If not, the target torque is calculated and output as 0. If so, the active return to center is turned off, and the process continues to Step 10; Step 10, the target angular velocity TargetAngSpd is processed to obtain the filtered target angular velocity TargetAngSpdFilt, and the actual angular velocity CurrentAngSpd is filtered to obtain the filtered actual angular velocity CurrentAngSpdFilt; Step 11, the angular velocity difference DeltaAngSpd = TargetAngSpdFilt-CurrentAngSpdFilt; Step 12, perform real vehicle debugging based on the angular velocity difference DeltaAngSpd and the current vehicle speed to determine the target torque closed-loop control parameter rule base; Step 13, determine the road conditions based on the steering angle acceleration change frequency, and determine the target torque reduction coefficient Pc based on the duration of the steering angle acceleration change frequency, and perform real vehicle debugging to determine the target torque reduction coefficient Pc parameter rule base; Step 14: Determine whether the frequency of change of steering angle acceleration is greater than the fixed value F. If so, calculate the target torque TargetTorq = angular velocity difference DeltaAngSpd (calculated value obtained through closed-loop control) × target torque reduction coefficient Pc. If not, calculate the target torque TargetTorq = angular velocity difference DeltaAngSpd (calculated value obtained through closed-loop control). Step 15: Perform signal processing on the target torque TargetTorq to obtain the final target torque TargetTorqFilt.

2. The calculation method based on EPS angle following control according to claim 1, characterized in that: The signal processing for the target angle AngReq, the target angular velocity TargetAngSpd, and the target torque TargetTorq includes amplitude limiting and filtering.

3. The calculation method based on EPS angle following control according to claim 1, characterized in that: Step 4 includes the following steps: Step 4a, under the vehicle debugging condition, at different vehicle speeds, a set of closed-loop control parameters are preset according to different angle differences DeltaAng, and the target angular velocity TargetAngSpd is obtained through closed-loop control; Step 4b, according to the value of the target angular velocity TargetAngSpd, the preset closed-loop parameter values ​​are corrected until the obtained target angular velocity TargetAngSpd meets the performance requirements; Step 4c, the corrected closed-loop parameter values ​​are recorded and stored in the target angular velocity closed-loop control parameter rule base.

4. The calculation method based on EPS angle following control according to claim 1, characterized in that: Step 5 includes the following steps: Step 5a, vehicle debugging condition, at different vehicle speeds, the advanced driver assistance system sends different target angles AngReq, and observes the angle difference, response time and angle difference DeltaAng between the current angle CurrentAng and the target angle AngReq of EPS; Step 5b, according to performance requirements, set the small angle boundary value SmallAngComp.

5. The calculation method based on EPS angle following control according to claim 1, characterized in that: Step 6 includes the following steps: Step 6a, under the vehicle debugging condition, obtain the small angle boundary values ​​that need to be compensated at different vehicle speeds; Step 6b, set a set of difference lookup tables, and obtain the target angular velocity gain value by looking up the table through the angle difference DeltaAng; Step 6c, correct the preset target angular velocity gain value according to the actual target angular velocity value until the obtained target angular velocity meets the performance requirements; Step 6d, record the corrected target angular velocity gain value and store it in the small angle gain Ps parameter rule library.

6. The calculation method based on EPS angle following control according to claim 1, characterized in that: Step 12 includes the following steps: Step 12a, vehicle debugging condition, at different vehicle speeds, a set of closed-loop control parameters are preset according to different angular velocity differences DeltaAngSpd, and the target torque TargetTorq is obtained through closed-loop control; Step 12b, according to the target torque TargetTorq, the motor drives the steering wheel to rotate the corresponding angle. Step 12c: Based on the following relationship between the current angle CurrentAng and the target angle TargetAng, correct the preset closed-loop parameter values ​​until the current angle CurrentAng meets the performance requirements; Step 12d: Record the corrected closed-loop parameter values ​​and store them in the target torque closed-loop control parameter rule library.

7. The calculation method based on EPS angle following control according to claim 6, characterized in that: The aforementioned tracking conditions include performance requirements for response time, steady-state error, and overshoot.

8. The calculation method based on EPS angle following control according to claim 1, characterized in that: Step 13 includes the following steps: Step 13a, calculate the number of times n in the time interval deltT that the detected angular acceleration value is first greater than a and then less than -a, or first less than a and then greater than a; Step 13b, calculate the steering angular acceleration change frequency = n / deltT. If the steering angular acceleration change frequency = 0, the road surface condition is normal; if the steering angular acceleration change frequency > 0, the road surface condition is bumpy. Step 13c: If the frequency of change of steering angle acceleration is greater than F and the duration of change of steering angle acceleration is less than t1, then the target torque reduction coefficient Pc = Pc1; if the frequency of change of steering angle acceleration is greater than F and the duration of change of steering angle acceleration is greater than t1 and less than t2, then the target torque reduction coefficient Pc = Pc2; if the frequency of change of steering angle acceleration is greater than F and the duration of change of steering angle acceleration is greater than t2 and less than t3, then the target torque reduction coefficient Pc = Pc3.

9. The calculation method based on EPS angle following control according to claim 8, characterized in that: The values ​​deltT, a, F, t1, Pc1, t2, Pc2, t3, and Pc3 mentioned are all calibration values ​​determined through actual vehicle testing.

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