A road feel optimization control method for differential braking system

Abstract

The present invention relates to a road feel optimization control method for a differential braking system, comprising the following steps: estimating the tire lateral force of the current vehicle based on a vehicle model and a nonlinear tire model; predicting the vehicle state at the next moment under a torque-free condition using the vehicle model; predicting the vehicle state at the next moment under a torque-differential condition using an improved vehicle model that adds an additional yaw moment; calculating the tire lateral force at the next moment under the torque-differential and torque-free conditions using the nonlinear tire model, subtracting the predicted values ​​to obtain a single-step front tire lateral force change prediction, and integrating the values ​​over time to obtain a continuous change in the tire lateral force; and correcting the desired torque of the power steering motor based on the continuous change in the tire lateral force. Compared to the prior art, the present invention has the advantages of predicting steering load torque changes and preemptively changing the assist torque to avoid changes in hand torque.

Description

Technical Field

[0001] The present invention relates to the field of driving road feel optimization, and in particular to a road feel optimization control method for a differential braking system. Background Art

[0002] With technological advancements and people's desire for more comfortable and safe travel, intelligent and electrified vehicles are becoming a growing trend. In this process, differential braking holds great promise for improving vehicle dynamics and driving experience. For example, differential braking can enhance a vehicle's steering ability, reducing driver stress, or improve vehicle stability, preventing dangerous situations like tailspin. Despite this promising development, differential braking systems still face the risk of interfering with driver control. While the system is in effect, even if the steering wheel angle remains unchanged, the additional yaw torque provided by differential braking causes changes in the lateral force on the wheels, which in turn alters the driver's hand torque.

[0003] The problem of hand force changes caused by active steering systems has been widely studied. In CN1137998721B, the steering wheel angle signal of the steering wheel angle sensor and the torque signal of the steering wheel torque sensor are received through the CAN bus to determine the driving direction and driving angle, and finally the auxiliary torque. Similarly, in CN107839749A, the ideal driving road feel characteristic diagram is designed through the vehicle system dynamics model to improve the driving experience. Furthermore, in CN112572606B, the working condition classification is performed based on SVM and BP neural network, and the torque assistance is weakened in dangerous working conditions to achieve the coordination of comfort and safety. The above technical solutions all need to estimate the change of hand torque by the change of front wheel angle. However, during the operation of the differential torque assistance system, the front wheel angle of the vehicle does not change. Therefore, the above solutions cannot handle the change of hand torque caused by the differential braking system.

[0004] Based on a steer-by-wire system, CN110606121B constructs a load state observer based on the steering motor's output torque to calculate the steering load torque. The desired assist torque is then optimized based on the changing steering load torque. Furthermore, in "Kalman Filter-Based Fusion Estimation Method of Steering Feedback Torque for Steer-by-Wire Systems," a Kalman filter is used to combine the steering load torque estimated by the vehicle system dynamics model with the steering motor's output torque to construct a steering load torque aggregate. This improves the steering load torque accuracy and enables further improvement in hand torque. However, these technical solutions are all passive, suppressing changes in steering torque after they occur. In "Study on Active Steering Control Mechanism and Its Interventional EPS System Steering Feel," an experimental relationship diagram is obtained between the additional steering angle applied by the assist system and the change in steering torque. In practical applications, steering torque changes are predicted by querying this relationship diagram. While some results have been achieved, the large number of operating conditions required and the workload are substantial. Furthermore, inadequate coverage of the relationship diagram can easily lead to erroneous assist torque decisions.

[0005] As can be seen from the above, in differential braking systems, the steering torque caused by changes in tire longitudinal force cannot be predicted using existing methods based on changes in front wheel angle. Furthermore, the approach of observing steering load changes through motor torque makes it difficult to predict these changes in advance. Therefore, existing research lacks a technical solution for optimizing road feel for torque changes caused by differential braking systems. Summary of the Invention

[0006] The purpose of the present invention is to provide a road feel optimization control method for a differential braking system to solve the problem of sudden changes in steering hand torque caused by the differential braking system performing assisted driving, which affects the driver's experience. It is an extension of the existing technical solution for solving the change in hand torque caused by changes in front wheel angle.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A road feel optimization control method for a differential braking system comprises the following steps:

[0009] S1: Estimate the tire lateral force of the current vehicle based on the vehicle two-degree-of-freedom model and nonlinear tire model;

[0010] S2: Based on the tire lateral force, the vehicle state at the next moment under the torque-free working condition is predicted using a two-degree-of-freedom vehicle model based on moment balance.

[0011] S3: Based on the tire lateral force, the vehicle state change rate under the torque differential condition is estimated using an improved vehicle two-degree-of-freedom model with an additional yaw moment, and the vehicle state at the next moment under the torque differential condition is predicted;

[0012] S4: Based on the predicted vehicle states at the next moment under the torque differential condition and the torque-free condition, the nonlinear tire model is used to calculate the tire lateral force at the next moment under the torque differential condition and the torque-free condition, respectively, and the predicted value of the single-step front tire lateral force change under the influence of the torque differential is obtained by subtracting the two values.

[0013] S5: Integrating the predicted value of the single-step front tire lateral force change based on time to obtain a continuous change in the tire lateral force;

[0014] S6: Corrects the desired torque of the power steering motor based on the continuous change in tire lateral force, suppresses changes in hand torque, and optimizes the driving experience.

[0015] The calculation method for estimating the tire lateral force of the current vehicle in S1 is:

[0016]

[0017]

[0018]

[0019]

[0020] Where: a and b are the distances between the front and rear wheelbases of the vehicle; m is the mass of the vehicle; v x and v y are the current lateral and longitudinal speeds of the vehicle respectively; γ is the yaw rate of the vehicle; g is the acceleration of gravity; μ is the ground adhesion coefficient; δ f is the steering wheel angle in the current state; α1 and α2 represent the front and rear wheel slip angles of the current vehicle respectively; F y1_p and F y2_p are the lateral forces of the front and rear wheels of the current vehicle respectively.

[0021] The calculation method for predicting the vehicle state at the next moment under the torque-free working condition in S2 is:

[0022]

[0023]

[0024] Where: γ and are the yaw rate and yaw acceleration, respectively; β and are the center of mass sideslip angle and the rate of change of the center of mass sideslip angle respectively; t is the controller calculation step size; γ * and β* The predicted values ​​of the vehicle's yaw rate and sideslip angle at the next moment; I z is the vehicle's moment of inertia.

[0025] The method for calculating the vehicle state at the next moment under the torque differential condition in S3 is:

[0026]

[0027]

[0028] Where: γ is the yaw angular velocity, is the estimated value of the vehicle yaw acceleration under the torque differential condition; β is the sideslip angle of the center of mass, is the rate of change of the vehicle's center of mass sideslip angle under differential torque conditions; and Represents the rate of change of vehicle state; and is the predicted value of the vehicle's yaw rate and sideslip angle at the next moment under the differential torque condition; ΔM is the estimated value of the additional yaw torque applied after the differential braking system works; t is the controller calculation step size; I z is the vehicle's moment of inertia.

[0029] The additional yaw moment estimate is:

[0030] ΔM=2*(F 11 +F 12 +F 21 +F 22 ) / L

[0031] Where: F 11 、F 12 、F 21 and F 22 They are the longitudinal forces applied to the front left, front right, rear left and rear right wheels of the car determined by the differential braking system; L is the wheelbase of the car.

[0032] The S4 comprises the following steps:

[0033] S41: Based on the nonlinear tire model and the vehicle state at the next moment under the zero-torque condition, predict the tire lateral force F under the zero-torque condition at the next moment y_p ;

[0034] S42: Based on the nonlinear tire model and the vehicle state at the next moment under the torque differential condition, predict the tire lateral force F under the torque differential condition at the next moment y_pm ;

[0035] S43: Calculate the predicted value F of the single-step front tire lateral force change under the influence of differential torque y_change :

[0036] F y_change =F y_pm -F y_p

[0037] Where: F y_change represents the sudden change in the front wheel lateral force caused by the differential braking system under a control step. The calculation method for the tire lateral force under the torque-free working condition is:

[0038] v y_p =β * *v x

[0039]

[0040]

[0041] Where: v y_p is the estimated value of the vehicle lateral speed at the next moment under the condition of no torque difference; α is the estimated value of the front wheel sideslip angle at the next moment under the condition of no torque difference; F y_p is the estimated value of the front wheel lateral force at the next moment under the torque-free working condition.

[0042] The calculation method of the tire lateral force under the differential torque condition is:

[0043]

[0044]

[0045]

[0046] Where: v y_pm is the estimated value of the vehicle lateral velocity at the next moment under the torque differential condition; α m is the estimated value of the front wheel slip angle at the next moment under the torque differential condition; F y_pm It is the estimated value of the front wheel lateral force at the next moment under the torque differential condition.

[0047] The calculation method of the continuous change of the tire lateral force in S5 is:

[0048]

[0049] Where: T is the continuous working time of the differential braking system in the primary auxiliary working condition; is the estimated value of the front wheel lateral force under the torque-free working condition at the i-th moment; is the estimated value of the front wheel lateral force under the torque differential condition at the i-th moment; is the predicted value of the single-step front tire lateral force change under the influence of the torque difference at the i-th moment; F t_changeis the change in front wheel lateral force caused by the differential braking system at moment T.

[0050] The correction method of the desired torque of the power steering motor in S6 is:

[0051] T ass =T asso +F t_change / i ceps

[0052] Where: T asso is the expected torque of the power steering motor based on the original power steering motor control decision; F t_change is the change in the front wheel lateral force caused by the differential braking system at time T; i ceps is the transmission ratio of the steering system; T ass is the corrected desired torque of the power steering motor.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] Additional yaw is the primary cause of changes in steering hand torque. This invention estimates the additional yaw caused by the additional longitudinal force of the decision and, in combination with the vehicle's two-degree-of-freedom model, inversely solves the change in steering load force. This achieves the goal of predicting changes in steering load torque and preemptively altering the assist torque to avoid changes in hand torque. Furthermore, because the additional yaw imposed by the differential braking system continuously affects the steering load torque, this invention integrates time to adapt to the changing steering hand torque caused by the continuous operation of the differential braking system. This addresses the issue of sudden changes in steering hand torque caused by the differential braking system during assisted driving, which impacts the driver experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a flow chart of the method of the present invention;

[0056] Figure 2 Schematic diagram of tire lateral force variation under an angular step test in an embodiment of the present invention;

[0057] Figure 3 Schematic diagram of tire lateral force changes under an oblique wave test in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0059] This embodiment provides a road feel optimization control method for a differential braking system. Figure 1 As shown, the following steps are included:

[0060] S1: Estimate the tire lateral force of the current vehicle based on the vehicle two-degree-of-freedom model and the nonlinear tire model.

[0061] This step is used to estimate the current tire lateral force in order to calculate the current moment of steering load torque. First, the tire slip angle is calculated using the vehicle's two-degree-of-freedom model, and then the tire lateral force is calculated based on the nonlinear tire model:

[0062]

[0063]

[0064]

[0065]

[0066] Where: a and b are the distances between the front and rear wheelbases of the vehicle; m is the mass of the vehicle; v x and v y are the current lateral and longitudinal speeds of the vehicle respectively; γ is the yaw rate of the vehicle; g is the acceleration of gravity; μ is the ground adhesion coefficient; δ f is the steering wheel angle in the current state; α1 and α2 represent the front and rear wheel slip angles of the current vehicle respectively; F y1_p and F y2_p are the lateral forces of the front and rear wheels of the current vehicle respectively.

[0067] S2: Based on the tire lateral force, the vehicle two-degree-of-freedom model based on torque balance is used to predict the vehicle state at the next moment under the torque-free working condition.

[0068] Specifically, the current vehicle state, namely the yaw acceleration and the rate of change of the center of mass slip angle, is estimated through a simplified vehicle two-degree-of-freedom model based on moment balance, and the yaw velocity and center of mass slip angle at the next moment are predicted based on them:

[0069]

[0070]

[0071] Where: γ and are the yaw rate and yaw acceleration, respectively; β and are the center of mass sideslip angle and the rate of change of the center of mass sideslip angle respectively; t is the controller calculation step size; γ * and β * The predicted values ​​of the vehicle's yaw rate and sideslip angle at the next moment; I z is the vehicle's moment of inertia.

[0072] S3: Based on the tire lateral force, the vehicle state change rate under the torque differential condition is estimated using an improved vehicle two-degree-of-freedom model with an additional yaw moment, and the vehicle state at the next moment under the torque differential condition is predicted.

[0073] Specifically, based on a simplified vehicle two-degree-of-freedom model based on moment balance, and considering the impact of the additional yaw moment on the vehicle posture caused by the lack of a differential braking system, the following improved vehicle two-degree-of-freedom model is constructed to predict the yaw rate and sideslip angle at the next moment:

[0074]

[0075]

[0076] Where: is the estimated value of the vehicle yaw acceleration under the torque differential condition; is the rate of change of the vehicle's sideslip angle under differential torque conditions; Represents the rate of change of vehicle state; and is the predicted value of the vehicle's yaw rate and sideslip angle at the next moment under the differential torque condition; ΔM is the estimated value of the additional yaw moment applied after the differential braking system works.

[0077] Based on the control target, the differential braking system controller determines the longitudinal tire force applied to each wheel. This decision value is related to the design of the differential braking system controller and is not the focus of this invention, so it will not be discussed here. The additional yaw moment can be obtained using the torque calculation formula:

[0078] ΔM=2*(F 11 +F 12 +F 21 +F 22 ) / L

[0079] Where: F 11 、F 12 、F 21 and F 22 They are the longitudinal forces applied to the front left, front right, rear left and rear right wheels of the car determined by the differential braking system; L is the wheelbase of the car.

[0080] S4: Based on the predicted vehicle states at the next moment under the torque differential condition and the torque-free condition, the nonlinear tire model is used to calculate the tire lateral force at the next moment under the torque differential condition and the torque-free condition, respectively, and the predicted value of the single-step front tire lateral force change under the influence of the torque differential is obtained by subtracting them.

[0081] S41: Based on the nonlinear tire model and the vehicle state at the next moment under the zero-torque condition, predict the tire lateral force F under the zero-torque condition at the next moment y_p ;

[0082]

[0083]

[0084]

[0085] Where: v y_p is the estimated value of the vehicle lateral speed at the next moment under the condition of no torque difference; α is the estimated value of the front wheel sideslip angle at the next moment under the condition of no torque difference; F y_p is the estimated value of the front wheel lateral force at the next moment under the torque-free working condition.

[0086] S42: Based on the nonlinear tire model and the vehicle state at the next moment under the torque differential condition, predict the tire lateral force F under the torque differential condition at the next moment y_pm ;

[0087]

[0088]

[0089]

[0090] Where: v y_pm is the estimated value of the vehicle lateral velocity at the next moment under the torque differential condition; α m is the estimated value of the front wheel slip angle at the next moment under the torque differential condition; F y_pm It is the estimated value of the front wheel lateral force at the next moment under the torque differential condition.

[0091] S43: Calculate the predicted value F of the single-step front tire lateral force change under the influence of differential torque y_change :

[0092] F y_change =F y_pm -F y_p

[0093] Where: F y_change Indicates the sudden change in front wheel lateral force caused by the differential braking system under one control step.

[0094] The purpose of steps S1-S4 is to calculate the lateral change of the wheel caused by applying the additional wheel lateral force, and to correct the desired torque of the power steering motor in advance by estimating its change value to suppress the change of the driver's hand torque.

[0095] S5: Integrate the predicted value of the single-step front tire lateral force change based on time to obtain the continuous change of the tire lateral force.

[0096] Since the additional yaw exerted by the differential braking system has a continuous effect on the steering load torque, the present invention adapts to the changing steering torque caused by the continuous operation of the differential braking system through a time integration scheme.

[0097]

[0098] Where: T is the continuous working time of the differential braking system in the primary auxiliary working condition; is the estimated value of the front wheel lateral force under the torque-free working condition at the i-th moment; is the estimated value of the front wheel lateral force under the torque differential condition at the i-th moment; is the predicted value of the single-step front tire lateral force change under the influence of the torque difference at the i-th moment; F t_change is the change in front wheel lateral force caused by the differential braking system at moment T.

[0099] S6: Corrects the desired torque of the power steering motor based on the continuous change in tire lateral force, suppresses changes in hand torque, and optimizes the driving experience.

[0100] In order to avoid the driving experience being affected by the change in hand torque caused by the differential braking system, the change in the front wheel lateral force caused by the differential braking system needs to be eliminated by correcting the assist strength of the power assist motor at the next moment. The formula for calculating the expected torque of the power assist motor at the next moment is constructed as follows:

[0101] T ass =T asso +F t_change / i ceps

[0102] Where: T asso is the expected torque of the power steering motor based on the original power steering motor control decision; F t_change is the change in the front wheel lateral force caused by the differential braking system at time T; i ceps is the transmission ratio of the steering system; T ass is the corrected desired torque of the power steering motor.

[0103] In order to verify the actual effect of the above method, this embodiment performs an angle step test and an oblique wave test respectively to verify the effect of the present invention on suppressing the change of tire lateral force.

[0104] 1. Angular step test

[0105] The vehicle speed is 80 km / s, the steering wheel angle is fixed at 40 degrees, the wheel side additional drive torque is 200 Nm, and the additional yaw moment is 513.5 Nm. This working condition corresponds to the emergency working condition of avoiding vehicle instability by the differential braking system. The results of the CarSim-MATLAB simulation are as follows: Figure 2 shown. Figure 2 Center: The dotted line shows the tire lateral force without torque differential; the dashed-dotted line shows the tire lateral force with torque differential; and the solid line shows the tire lateral force after torque differential compensation. As can be seen from the figure, the present invention has a significant effect in suppressing the change in tire lateral force under this operating condition.

[0106] 2. Ramp test

[0107] The vehicle speed is 80 km / s, the steering wheel angle is fixed at 40 degrees, the wheel side additional driving torque is 44 Nm / s, and the additional yaw torque is 115 Nm / s. This working condition corresponds to the working condition where the differential braking system assists the driver in steering to reduce the driver's driving burden. The results of the CarSim-MATLAB simulation are as follows Figure 3 shown. Figure 3 Center: The dotted line shows the tire lateral force without torque differential; the dashed-dotted line shows the tire lateral force with torque differential; and the solid line shows the tire lateral force after torque differential compensation. As can be seen from the figure, the present invention has a significant effect in suppressing the change in tire lateral force under this operating condition.

[0108] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A road feel optimization control method for a differential braking system, characterized in that: The following steps are involved: S1: Estimate the tire lateral force of the current vehicle based on the vehicle two-degree-of-freedom model and nonlinear tire model; S2: Based on the tire lateral force, the vehicle state at the next moment under the torque-free working condition is predicted using a two-degree-of-freedom vehicle model based on moment balance. S3: Based on the tire lateral force, the vehicle state change rate under the torque differential condition is estimated using an improved vehicle two-degree-of-freedom model with an additional yaw moment, and the vehicle state at the next moment under the torque differential condition is predicted; S4: Based on the predicted vehicle states at the next moment under the torque differential condition and the torque-free condition, the nonlinear tire model is used to calculate the tire lateral force at the next moment under the torque differential condition and the torque-free condition, respectively, and the predicted value of the single-step front tire lateral force change under the influence of the torque differential is obtained by subtracting the two values. S5: Integrating the predicted value of the single-step front tire lateral force change based on time to obtain a continuous change in the tire lateral force; S6: Corrects the desired torque of the power steering motor based on the continuous change in tire lateral force, suppresses changes in hand torque, and optimizes the driving experience.

2. The road feel optimization control method for a differential braking system according to claim 1, characterized in that: The calculation method for estimating the tire lateral force of the current vehicle in S1 is: Where: a and b are the distances between the front and rear wheelbases of the vehicle; m is the mass of the vehicle; v x and v y are the current lateral and longitudinal speeds of the vehicle respectively; γ is the yaw rate of the vehicle; g is the acceleration of gravity; μ is the ground adhesion coefficient; δ f is the steering wheel angle in the current state; α1 and α2 represent the front and rear wheel slip angles of the current vehicle respectively; F y1_ and F y2_ are the lateral forces of the front and rear wheels of the current vehicle, respectively.

3. The road feel optimization control method for a differential braking system according to claim 2, characterized in that: The calculation method for predicting the vehicle state at the next moment under the torque-free working condition in S2 is: Where: γ and are the yaw rate and yaw acceleration, respectively; β and are the center of mass sideslip angle and the rate of change of the center of mass sideslip angle respectively; t is the controller calculation step size; γ * and β * The predicted values ​​of the vehicle's yaw rate and sideslip angle at the next moment; I z is the vehicle's moment of inertia.

4. The road feel optimization control method for a differential braking system according to claim 2, characterized in that: The method for calculating the vehicle state at the next moment under the torque differential condition in S3 is: Where: γ is the yaw angular velocity, is the estimated value of the vehicle yaw acceleration under the torque differential condition; β is the sideslip angle of the center of mass, is the rate of change of the vehicle's sideslip angle under differential torque conditions; and Represents the rate of change of vehicle state; and is the predicted value of the vehicle's yaw rate and sideslip angle at the next moment under the differential torque condition; ΔM is the estimated value of the additional yaw moment applied after the differential braking system is activated; t is the controller calculation step size; I z is the vehicle's moment of inertia.

5. The road feel optimization control method for a differential braking system according to claim 4, characterized in that: The additional yaw moment estimate is: ΔM=2*(F 11 +F 12 +F 21 +F 22 ) / L Where: F 11 、F 12 、F 21 and F 22 They are the longitudinal forces applied to the front left, front right, rear left and rear right wheels of the car determined by the differential braking system; L is the wheelbase of the car.

6. The road feel optimization control method for a differential braking system according to claim 1, characterized in that: The S4 comprises the following steps: S41: Based on the nonlinear tire model and the vehicle state at the next moment under the zero-torque condition, predict the tire lateral force F under the zero-torque condition at the next moment y_p ; S42: Based on the nonlinear tire model and the vehicle state at the next moment under the torque differential condition, predict the tire lateral force F under the torque differential condition at the next moment y_pm ; S43: Calculate the predicted value F of the single-step front tire lateral force change under the influence of differential torque y_change : F y_change =F y_pm -F y_p Where: F y_change Indicates the sudden change in front wheel lateral force caused by the differential braking system under one control step.

7. The road feel optimization control method for a differential braking system according to claim 3, characterized in that: The calculation method of the tire lateral force under the no-torque condition is: v y_p =β * *v x Where: v y_p is the estimated value of the vehicle lateral speed at the next moment under the no-torque condition; α is the estimated value of the front wheel sideslip angle at the next moment under the no-torque condition; F y_p is the estimated value of the front wheel lateral force at the next moment under the torque-free working condition.

8. The road feel optimization control method for a differential braking system according to claim 4, characterized in that: The calculation method of the tire lateral force under the differential torque condition is: Where: v y_pm is the estimated value of the vehicle lateral velocity at the next moment under the torque differential condition; α m is the estimated value of the front wheel slip angle at the next moment under the torque differential condition; F y_pm It is the estimated value of the front wheel lateral force at the next moment under the torque differential condition.

9. The road feel optimization control method for a differential braking system according to claim 1, characterized in that: The calculation method of the continuous change of the tire lateral force in S5 is: Where: T is the continuous working time of the differential braking system in the primary auxiliary working condition; is the estimated value of the front wheel lateral force under the torque-free working condition at the i-th moment; is the estimated value of the front wheel lateral force under the torque differential condition at the i-th moment; is the predicted value of the single-step front tire lateral force change under the influence of the torque difference at the i-th moment; F t_change is the change in front wheel lateral force caused by the differential braking system at moment T.

10. The road feel optimization control method for a differential braking system according to claim 1, characterized in that: The correction method of the desired torque of the power steering motor in S6 is: T ass =T asso +F t_change / i ceps Where: T asso is the expected torque of the power steering motor based on the original power steering motor control decision; F t_change is the change in the front wheel lateral force caused by the differential braking system at time T; i ceps is the transmission ratio of the steering system; T ass is the corrected desired torque of the power steering motor.

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