Electric Power Steering System Research Articles

Parameter Estimation, Robust Controller Design and Performance Analysis for an Electric Power Steering System

This paper presents a parameter estimation, robust controller design and performance analysis for an electric power steering (EPS) system. The parametrical analysis includes the EPS parameters and disturbances, such as the assist motor parameters, sensor-measurement noise, and random road factors, allowing the EPS stability to be extensively investigated. Based on the loop-shaping technique, the system controller is designed to increase the EPS stability and performance. The loop-shaping procedure is proposed to minimize the influence of system disturbances on the system outputs. The simplified refined instrumental variable (SRIV) algorithm, least squares state variable filter (LSSVF) algorithm and instrumental variable state variable filter (IVSVF) algorithm are applied to reduce the model mismatching between the theoretical EPS models and the real EPS model, as the EPS parameters can be accurately identified based on the experimental EPS data. The performance of the proposed method is thus compared to that of the proportional-integral-derivative (PID) test bench results for the EPS system. The experimental results demonstrated that the proposed loop-shaping controller provides good tracking performance while ensuring the stability of the EPS system.

Research on Control of Intelligent Vehicle Human-Simulated Steering System Based on HSIC

The experienced drivers with good driving skills are used as objects of learning, and road steering test data of skilled drivers are collected in this article. First, a nonlinear fitting was made to the driving trajectory of skilled driver in order to achieve human-simulated control. The segmental polynomial expression was solved for two typical steering conditions of normal right-steering and U-turn, and the hp adaptive pseudo-spectral method was used to solve the connection problem of the vehicle segmental driving trajectory. Second, a new Electric Power Steering (EPS) system was proposed, and the intelligent vehicle human-simulated steering system control model based on human simulated intelligent control (HSIC) was established in Simulink/Carsim joint simulation environment to simulate and analyze. Finally, in order to further verify the effectiveness of the proposed algorithm in this article, an intelligent vehicle steering system test bench with a steering resistance torque simulation device was built, and the dSPACE rapid prototype controller was used to realize human-simulated intelligent control law. The results show that the human-simulated steering control algorithm is superior to the traditional proportion integration differentiation (PID) control in the tracking effect of the steering characteristic parameters and passenger comfort. The steering wheel angle and torque can better track the angle and torque variation curve of real vehicle steering experiment of the skilled driver, and the effectiveness of the intelligent vehicle human-simulated steering control algorithm based on HSIC proposed in this article is verified.

H∞ static output feedback control for electrical power steering subject to actuator saturation via fuzzy Lyapunov functions

This paper presents an H∞ static output-feedback control of electrical power steering (EPS) subject to actuator saturation. It deals with different practical problems in designing control of EPS systems, such as unavailability for measurement of the sideslip angle, friction effect, disturbances and the assist motor input current optimization. In order to guarantee good and stable driving, the nonlinear model of the EPS combined with bicycle model of electrical vehicles is used. Firstly, a new Takagi-Sugeno model is established, then using a fuzzy Lyapunov function, an H∞ static output-feedback is designed in terms of linear matrix inequalities. Finally, the proposed control schemes are applied to an EPS system. Simulation results and comparison with previous works show the effectiveness of the proposed control methods.

A Hierarchical Strategy for the Electro-hydraulic Coupling Steering System on Commercial Vehiclescommercial vehicles, electro-hydraulic coupling steering, characteristic curve, hierarchical strategy

In order to improve the steering performance of commercial vehicles, this paper investigates a novel electro-hydraulic coupling steering (EHCS) system based on the electric power steering (EPS) system and the hydraulic power steering (HPS) system. A hierarchical strategy is proposed for the EHCS system, including a mode judgment controller, an assistance controller and an alignment controller. Fuzzy rules are established in the assistance controller to match the electric and hydraulic power assistance curves, so as to achieve a good assistance effect. The proposed EHCS system and its control strategy are validated in the co-simulation of the Simulink and the Trucksim, the results of which indicate a great improvement in the steering portability and self-alignment, compared with the EPS and the HPS.

Design Optimization of Vehicle EHPS System Based on Multi-objective Genetic Algorithm

Electric hydraulic power steering (EHPS) system has been widely used in large and medium cars, which plays an important role in determining the energy loss, driving safety and driving comfort of vehicles. This work mainly discusses the parameter design of the EHPS system based on the multi-objective optimization algorithm. Since there is no explicit standard for the performance indexes of EHPS system, this work proposes to take the energy consumption, steering road feel, steering sensibility and steering stability as the main performance indexes of EHPS system. Based on these, a multi-objective optimization model is established with the non-dominated sorting genetic algorithm-III based on fitness function (NSGA-III-FF), which has better convergence than the original NSGA-III. Simulation results show that NSGA-III-FF enhances the comprehensive performance of the EHPS system, which can successfully achieve the goal of multiobjective optimization for steering flexibility, steering road feel, and energy loss while ensuring the steering stability.

Multi-parametric model predictive control for autonomous steering using an electric power steering system

Electric power steering systems have been used to generate assist torque for driver comfort. This study makes use of the functionality of electric power steering systems for autonomous steering control without driver torque. A column-type electric power steering test bench, equipped with a brushless DC motor as an assist motor, and the Infineon TriCore AURIX TC 277 microcontroller was used in this study. Multi-parametric model predictive control is based on a model predictive control–based approach that employs a multi-parametric quadratic programming technique. This technique allows the reduction of the huge computational burden resulting from the online optimization in model predictive control. The proposed controller obtains an optimal input based on multi-parametric quadratic programming at each sampling time. The weighting matrix definition, which is the main task when designing the proposed controller, was analyzed. The experimental results of the step response of the steering wheel angle verified the tracking ability of the proposed controller for different ranges of the prediction horizon. Since the computational loads are directly related to functional safety, the results of this study support the use of the multi-parametric model predictive control scheme as an effective control method for autonomous steering control.

TS Fuzzy Model-Based Controller Design for a Class of Nonlinear Systems Including Nonsmooth Functions

This paper proposes a novel robust controller design for a class of nonlinear systems including hard nonlinearity functions. The proposed approach is based on Takagi–Sugeno (TS) fuzzy modeling, nonquadratic Lyapunov function, and nonparallel distributed compensation scheme. In this paper, a novel TS modeling of the nonlinear dynamics with signum functions is proposed. This model can exactly represent the original nonlinear system with hard nonlinearity while the discontinuous signum functions are not approximated. Based on the bounded-input-bounded-output stability scheme and ${L_{1}}$ performance criterion, new robust controller design conditions in terms of linear matrix inequalities are derived. Three practical case studies, electric power steering system, a helicopter model and servo-mechanical system, are presented to demonstrate the importance of such class of nonlinear systems comprising signum function. Furthermore, to show the superiorities of the proposed approach, it is applied to these systems; and, the experimental real-time hardware-in-the-loop results are compared with the published literature with the same topic.

Noise and vibration suppression of electric power steering systems: a survey

Electric power steering (EPS) systems have become the ideal steering system for most vehicles because of the generated torque assist mechanism making steering easier for drivers. However, EPS systems generate unwanted noise and vibration that can adversely affect the comfort and health of drivers. Numerous studies have been conducted to examine the source of vibrations. Various isolation techniques including passive, active, or semi active have been proposed for achieving best noise and vibration attenuation. Discrete and distributed mathematical models have been employed to predict the dynamic response of EPS systems. This paper presents a state-of-the-art review of mathematical modelling, vibration isolation methods, and optimisation techniques used for improving the design of EPS systems.

Noise and vibration suppression of electric power steering systems: a survey

Electric power steering (EPS) systems have become the ideal steering system for most vehicles because of the generated torque assist mechanism making steering easier for drivers. However, EPS systems generate unwanted noise and vibration that can adversely affect the comfort and health of drivers. Numerous studies have been conducted to examine the source of vibrations. Various isolation techniques including passive, active, or semi active have been proposed for achieving best noise and vibration attenuation. Discrete and distributed mathematical models have been employed to predict the dynamic response of EPS systems. This paper presents a state-of-the-art review of mathematical modelling, vibration isolation methods, and optimisation techniques used for improving the design of EPS systems.

Magnet Shape Design and Verification for SPMSM of EPS System Using Cycloid Curve

A low cogging torque and torque ripple are the most important qualities for electric power steering (EPS) motors. Therefore, various design methods are employed to obtain EPS motors with these qualities. In this study, a novel design method for the pole shape was developed by adopting a cycloid curve to realize the desired qualities of EPS motors without reducing the torque. An evaluation index ( $\delta q$ ) was used to design the pole shape of the magnet and to compare the pole shape between the proposed method and the conventional method. The proposed and conventional methods were applied to existing machine designs, and their performances were compared using a finite-element analysis (FEA). The results of the FEA and prototype tests indicated an improved motor performance for the proposed method.

Fast fault-tolerant control of electric power steering systems in the presence of actuator fault

Electric power steering is an advanced steering system that uses an electric motor to improve steering comfort of the car. As a result, the failures in the electric motor can lead to additional fault modes and cause damage of the electric power steering system performance. Hence, to ensure the stability of this latter, the present paper proposes a new method to reconfigure the fault control. A novelty approach of fast fault estimation based on adaptive observer is also proposed. Moreover, to guarantee optimal and fast control, a fault-tolerant control based on inverse bond graph modeling is designed to construct the behavior of the nominal system. The simulation and the experimental results on a real electric power steering system reveal the importance of the control strategy and show that the proposed approach works as intended.

АНАЛІЗ ПРОБЛЕМ СИСТЕМИ РУЛЬОВОГО КЕРУВАННЯ ТРОЛЕЙБУСІВ ТА ПЕРСПЕКТИВИ ЇХ ВИРІШЕННЯ

Electric transport is a necessary part of infrastructure of large cities and is used for the transportation of passengers or cargo. Therefore, the issue of its constant updating or modernization and improvement of some elements is acute. The analysis of problems during the operation of trolleybuses was carried out and the object of modernization of steering control on the basis of the trolleybus brand LAZ-E183 was determined. The purpose of the work is to develop steering control of simplified design and increased energy efficiency. The object of research is design the amplifiers of the steering system of trolleybuses. The subject of the study is processes and characteristics that affect energy efficiency of steering systems. The scientific novelty is an innovative solution to increase the energy efficiency of the steering system of trolleybuses through the use of an electric motor with rolling rotor, which allows to realize a high torque unlike traditional electric motors. The practical value of a new technical solution is develop an electric power steering system of trolleybus through the use of an electric motor with rolling rotor, as well as in reducing the size and simplified design of the steering booster. The application of the engine with rolling rotor makes it possible to reduce the power consumption of the on-board network by switching on the electric power steering only at the moment of turning the trolley, which also increases the energy efficiency of the steering control.

A Rough Set-Theory-Based Fault-Diagnosis Method for an Electric Power-Steering System

Electric power steering (EPS) is a fundamental part of an automotive system. Deviations from its anticipated operation have an impact on vehicle driving performance and handling, and could cause severe safety concerns. Reliable and efficient fault detection and diagnosis (FDD) methods are needed for EPS to guarantee the safe operation of the vehicle and for improved repairability of faulty components. In this paper, we develop an integrated model-based and data-driven FDD approach for the EPS system. Specifically, we develop a physics-based model of the EPS system and conduct a number of fault injection experiments to derive fault-sensor measurement dependencies. Then, we investigate various FDD schemes to detect and isolate the faults with special emphasis on rough set-theory-based fault classification. Finally, we compare its fault-classification accuracies with those from traditional classification methods. We demonstrate that the rough set-theory-based FDD approach is robust to missing data.

Electric Power Steering System Control Strategy Based on Robust H∞ Control for Electric Forklift

The dynamic model of the Electric Power Steering (EPS) system for electric forklifts and the two-degree-of-freedom (2DOF) forklift models has been established. Based on the control target of electric forklift EPS, a generalized EPS control model with model perturbation and interference is established. The standard H∞control model of the EPS system is transformed, and the EPS generalized state equation of electric forklift is derived. The principle of robust control with genetic optimization is expounded, aiming at the parameters optimization of the weighted function of H∞control model, the constraint function of the genetic algorithm (GA) is constructed, and the robust controller of genetic optimization is derived. Taking the electric forklift TFC20 as the research object, according to the actual data on the forklift, the system model is established in MATLAB, and the effects of PID control, robust control, and genetic robust control are compared, the results show that the power steering characteristic of the robust control is better than the power steering characteristic of the PID control, and the stability of the forklift under the control of robust control is better. Also, the power steering characteristic of the H∞ controller with GA optimization is better than that of an unoptimized one, and its robustness is better, under external pavement interference, the following ability is stronger for the ideal current and the steering is more stable.

Coupling Control Strategy of Force and Displacement for Electric Differential Power Steering System of Electric Vehicle With Motorized Wheels

This paper presents a coupling control strategy of force and displacement for an electric differential power steering (EDPS) system to improve steering maneuverability and handling stability of electric vehicles with motorized wheels. In order to investigate mutual influences between vehicles and drivers, models of the EDPS system, the vehicle, the tire as well as the actuate motor are introduced. Then, by analyzing key factors that affect the interaction between vehicles and drivers, the optimum hand wheel torque of the EDPS system is developed and actualized by torque difference between two front wheels based on the ${\text{H}}_{2}{\text{/ H}}_{{{\infty }}}$ control method. In addition, a yaw rate control method is schemed to diminish the yaw moment interference to vehicles caused by the torque difference between two front wheels, and μ-synthesis theory is applied here to improve the yaw rate tracking performance as well as attenuate influences of system uncertainties and disturbances. Finally, simulations by MATLAB/Simulink and hardware-in-the-loop experiments based on dSPACE are conducted and effectiveness of the proposed control strategy is demonstrated by simulation and experiment results and numerical analyses.

The manufacturing method of the composite worm gear housing using the cold injection

In the work the innovation manufacturing method of the composite worm gear housing of the electric power steering system was presented. Modification of the worm gear housing of the electric power steering system consisted in changing the material from which it will be manufactured. Until now, gear housings were made of aluminum by hot injection method. The present works aim at using the pDCPD material and the cold injection method into manufacturing the new generation of the worm gear housing. The planned change was aimed at eliminating the machining process of the cast aluminum body and reducing its mass. In the work was assumed, that the assembled worm gear housing, with all cooperating elements, will be manufactured using the cold injection method. As a result of the manufacturing process the finished product in the worm gear form of the electric power steering system will be obtained. In addition, the geometrical form and the dimensions system of the support elements were determined in relation to the assembled worm and the worm wheel together with the bearing system. The presented method allows eliminating the expensive and time-consuming process of machining of the molding gear housing.

An investigation on the energy-saving effect of a hybrid electric-power steering system for commercial vehicles

This article describes an investigation on the energy consumption of an alternative hybrid electric power steering system. The conventional hydraulic power steering system that is widely used in commercial vehicles can provide high steering-feel and reliability performances. However, since the combustion engine drives the pump, the hydraulic power steering system is energetically inefficient. To cope with this disadvantage of the hydraulic power steering system and to provide a technical base for the steering-related advanced driver assistance system, the Hybrid electric power steering system offers a solution for heavy commercial vehicles. The “Hybrid” of the title means that, for heavy commercial vehicles, the electric power steering system and electro-hydraulic power steering system are integrated in a ball-nut steering system. In this paper, to verify the energy-saving effect of the Hybrid electric power steering system, a dynamic model of the Hybrid electric power steering system was developed to estimate the energy consumption in the steering system. Furthermore, the fuel-efficiency test for the Hybrid electric power steering system were conducted while replacing the two steering systems (the conventional hydraulic power steering and Hybrid electric power steering system) in one vehicle on the chassis dynamometer for the proposed driving cycle. The driving cycle including the steering-angle profile has been developed to clearly investigate the effect on the energy-saving potential by the types of the steering system (hydraulic power steering and Hybrid electric power steering). The simulation results of the energy-consumption estimation showed that the hybrid electric power steering system can reduce the steering-system energy consumption by more than 50% under the proposed driving cycle. Also, the vehicle testing of the chassis dynamometer revealed that the Hybrid electric power steering system can improve the fuel efficiency of the vehicle by 1% for the specified driving cycle.

EPS Current Tracking Method Research Based on Hybrid Sensitivity H∞ Control Algorithm

For electric power steering system (EPS), road interference, noise of the sensor, and the uncertainty of the steering system may make EPS control effect and the driver's road sense worse. EPS system which takes advantage of good current tracking ability, good anti-interference ability, and good operation stability is becoming more and more important in automotive research. The traditional H∞ control algorithm can solve the system uncertainty theoretically, but it cannot solve the contradiction between robustness and performance without considering the performance of the system. Therefore, this paper proposes a EPS current tracking method based on the hybrid sensitivity H∞ control algorithm, which takes the current tracking performance as one of the control objectives, so that the system can maximize the robustness and performance. Firstly, the dynamic model of EPS is established. Then, the two-degree-of-freedom vehicle model and tire model are introduced. The state space equation of the system is constructed on the basis of the system state space with random disturbance signals, the hybrid sensitivity H∞ controller is designed in the sensitivity index design, and the proposed algorithm can use weighting function to minimize the performance of the current tracking error as well as the robustness of the yaw rate error in response to robustness. Simulation analysis and experimental verification of EPS system are also carried out. The results show that the control method of the hybrid sensitivity H∞ can better achieve EPS target current tracking, effectively suppress the effect of external interference and noise, improve the system performance and robustness, ensure the driver get good road sense, and improve the system of steering stability.

Fault Tolerant Control of Electric Power Steering System with Sensor Fault

Objectives: A novel approach for diagnosis and control design that compensates sensor fault effects in electric power steering system (EPS) is proposed. Methods/Statistical Analysis: A Luenberger observer is used to estimate the fault of torque sensor for the EPS system. The fault tolerant control (FTC) based an inverse model of bond graph (BG) is used to compensate the fault of torsion bar sensor signal. The proposed control strategy presents an opportunity to improve EPS system performance and also reduce system complexity. Findings: The findings achieved are simulation tests, showed that the application of the synthesized law on the experimental of the EPS system show the effectiveness of the proposed approach. Application: The fault tolerant control based a bond graph model is an important step allows an improvement the rapidity of the compensation of fault in the system. Keywords: Bond Graph, Diagnosis, Fault Tolerant Control, Inverse Bond Graph

Worm gear efficiency model considering misalignment in electric power steering systems

Abstract. This study proposes a worm gear efficiency model considering misalignment in electric power steering systems. A worm gear is used in Column type Electric Power Steering (C-EPS) systems and an Anti-Rattle Spring (ARS) is employed in C-EPS systems in order to prevent rattling when the vehicle goes on a bumpy road. This ARS plays a role of preventing rattling by applying preload to one end of the worm shaft but it also generates undesirable friction by causing misalignment of the worm shaft. In order to propose the worm gear efficiency model considering misalignment, geometrical and tribological analyses were performed in this study. For geometrical analysis, normal load on gear teeth was calculated using output torque, pitch diameter of worm wheel, lead angle and normal pressure angle and this normal load was converted to normal pressure at the contact point. Contact points between the tooth flanks of the worm and worm wheel were obtained by mathematically analyzing the geometry, and Hertz's theory was employed in order to calculate contact area at the contact point. Finally, misalignment by an ARS was also considered into the geometry. Friction coefficients between the tooth flanks were also researched in this study. A pin-on-disk type tribometer was set up to measure friction coefficients and friction coefficients at all conditions were measured by the tribometer. In order to validate the worm gear efficiency model, a worm gear was prepared and the efficiency of the worm gear was predicted by the model. As the final procedure of the study, a worm gear efficiency measurement system was set and the efficiency of the worm gear was measured and the results were compared with the predicted results. The efficiency considering misalignment gives more accurate results than the efficiency without misalignment.