Comparative Study of Rack Force Estimation for Electric Power Assist Steering System

2017 ◽  
Author(s):  
Yijun Li ◽  
Taehyun Shim ◽  
Dexin Wang ◽  
Timothy Offerle
Keyword(s):  
Control System ◽  
Electric Power ◽  
Vehicle Dynamics ◽  
System Development ◽  
Steering System ◽  
Estimation Methods ◽  
Simulation Environment ◽  
Force Estimation ◽  
Adaptation Algorithm ◽  
Estimation Algorithms

For an electric power assist steering (EPAS) control system, it is important to know the rack force information to improve the steering feel control performance. Since there is no direct measurement of rack force in current EPAS system, there have been various rack force estimation algorithms proposed for the control system development. In this paper, two existing rack force estimation methods (based on steering system dynamics and vehicle dynamics) have been implemented in the simulation environment to compare its performance. The effectiveness and limitations of two methods have been analyzed using a simulation of high fidelity EPAS model with various inputs conditions. In addition, new adaptation algorithm is proposed to further improve the estimation performance of the existing methods.

Effect of Load-Dependent Friction on the Estimation of Rack Force in Electric Power-Assisted Steering System

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Yijun Li ◽  
Taehyun Shim ◽  
Dexin Wang ◽  
Timothy Offerle
Keyword(s):  
Electric Power ◽  
A Priori ◽  
Estimation Method ◽  
Estimation Algorithm ◽  
Steering System ◽  
Estimation Methods ◽  
Current Steering ◽  
Force Estimation ◽  
Operation Conditions ◽  
Friction Estimation

The rack force is valuable information for a vehicle dynamics control system, as it relates closely to the road conditions and steering feel. Since there is no direct measurement of rack force in current steering systems, various rack force estimation methods have been proposed to obtain the rack force information. In order to get an accurate rack force estimate, it is important to have knowledge of the steering system friction. However, it is hard to have an accurate value of friction, as it is subject to variation due to operation conditions and material wear. Especially for the widely used column-assisted electric power steering (C-EPAS) system, the load-dependent characteristic of its worm gear friction has a significant effect on rack force estimation. In this paper, a rack force estimation method using a Kalman filter and a load-dependent friction estimation algorithm is introduced, and the effect of C-EPAS friction on rack force estimator performance is investigated. Unlike other rack force estimation methods, which assume that friction is known a priori, the proposed system uses a load-dependent friction estimation algorithm to determine accurate friction information in the steering system, and then a rack force is estimated using the relationship between steering torque and angle. The effectiveness of this proposed method is verified by carsim/simulink cosimulation.

Design and Stabilization Analysis of the Parabola-Type Assistance Characteristic of Electric Power Steering System

2013 ◽  
Vol 779-780 ◽  
pp. 556-559 ◽  
Author(s):  
Guo Qing Geng
Keyword(s):  
Control System ◽  
Electric Power ◽  
Computer Control ◽  
Steering System ◽  
Computer Control System ◽  
Electric Power Steering ◽  
Power Steering System ◽  
Curve Type ◽  
Power Steering ◽  
Electric Power Steering System

In order to realize the curve-type assistance characteristic of the electric power steering system , the parabola-type assistance characteristic is brought out, and realizing it by designing the electric power steering system which is controlled by computer. And then math model of computer control system is constructed, and adopting Z-transform to analysis the stabilization of the system. The result shows that computer control system can realize the curve-type assistance characteristic.

Rack Force Estimation for Electric Power Steering

2015 ◽  
Author(s):  
Thomas Weiskircher ◽  
Steve Fankem ◽  
Beshah Ayalew
Keyword(s):  
Electric Power ◽  
Steering System ◽  
Force Estimation ◽  
Test Rig ◽  
Electric Power Steering ◽  
Power Steering ◽  
Electric Power Steering System ◽  
Estimation Scheme ◽  
Friction Identification ◽  
Linear Disturbance

This paper discusses a steering rack force estimation scheme using test-rig generated models. In addition to friction identification, a model of the electric power steering system is identified by the use of the instrumented test-rig. It turns out that the friction in the steering system is highly load-dependent, asymmetric with respect to speed, and shows no Stribeck effects. A LuGre model is adopted and fitted to approximate the measured dynamic friction. Consequently, this model is used in a friction compensator which is combined with a linear disturbance observer to estimate the steering rack force. The proposed estimation scheme is analyzed via evaluated system simulations and experiments on the steering system test-rig. Finally, considering the fact that the friction level varies with each steering device manufactured and installed, the paper discusses algorithms for friction level adaptation.

Integrated LQR Control of Automobile Anti-Rollover System and Electrical Power Steering System

2014 ◽  
Vol 505-506 ◽  
pp. 349-355 ◽  
Author(s):  
Cong Liao ◽  
Xin Ye Wu ◽  
Hong Wu Huang ◽  
Qiu Fang
Keyword(s):  
Control System ◽  
Electric Power ◽  
Active Suspension ◽  
Steering System ◽  
System Model ◽  
Optimal Control Strategy ◽  
Electric Power Steering ◽  
Power Steering System ◽  
Power Steering ◽  
Electric Power Steering System

Based on the interference characteristics of the active suspension anti-rollover control system and electric power steering system, combining vehicle active suspension anti-rollover control system model, electric power steering system model and the steering model, the automobile system dynamic model was established. The optimal control strategy of LQR(linear quadratic regulator) was designed, and integrated control system of the anti-rollover control system and electric power steering was realized. Under Matlab/Simulink, the simulation was done and the results show that the presented control scheme can improve handiness of electric power steering system, and has a good anti-roll and anti-pitch ability.

A Research on Impact Compensation Control Strategy of Electric Power Steering System Based on Whole Vehicle Dynamics

2012 ◽  
Vol 241-244 ◽  
pp. 1969-1973
Author(s):  
Guang Xing Tan ◽  
Yang Song ◽  
Chuan Lin ◽  
Wen Guo Jian
Keyword(s):  
Electric Power ◽  
Control Strategy ◽  
Vehicle Dynamics ◽  
Steering System ◽  
Slip Angle ◽  
Electric Power Steering ◽  
Power Steering System ◽  
Power Steering ◽  
Electric Power Steering System ◽  
The Stability

In order to improve the vehicles steering performance, based on a whole vehicle dynamics model，the electric power steering system(EPS) control strategy is studied under road surface impact condition. An AIS controller is executed on the output current of assist motor hence further improving control effects. Accompanied the methodology of combining the full vehicle model in CarSim and EPS model in MATLAB, this co-simulation model is verified by test data. By comparison yaw rate and slip angle of the results show that: implementing the control of EPS by AIS compensation strategy is an effective way of enhancing the capability of steering and the stability of operation, which can make it more accurate and flexible.

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