Electric Power Steering System Control Strategies

Electric power steering (EPS) systems have become ubiquitous in modern vehicles, offering adjustable assistance, improved fuel efficiency and integration with advanced driver‐assistance systems. At their core, EPS units employ an electric motor to provide steering torque proportional to driver input and vehicle speed. Control strategies aim to balance torque assistance, steering feel and stability under varying road conditions. Early approaches relied on proportional–integral–derivative (PID) loops, which are simple but sensitive to parameter changes and external disturbances. More recent developments have introduced observer-based methods and robust control laws that reject disturbances arising from friction, tyre forces and motor dynamics. Adaptive algorithms tune control gains in real time to maintain consistent steering behaviour across manufacturing tolerances and wear. Sliding mode controllers ensure robustness to uncertainties but can induce chattering unless modulated. Active disturbance rejection control (ADRC) has gained traction by directly estimating and compensating aggregate disturbances via an extended state observer. Return-to-centre regulation and fault-tolerant schemes further enhance driver safety and support autonomy by maintaining controllability under sensor or actuator failures. Overall, EPS control strategies continue evolving towards greater integration with vehicle dynamics control, electrification and automated driving functions, emphasising reliability and driver comfort.

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Electric Power Steering System Control Strategies publication trend

The graph below shows the total number of articles in electric power steering system control strategies across all publications each year (not limited to Nature Index journals).

Technical terms

Active disturbance rejection control (ADRC): A control methodology that uses an observer to estimate and compensate total disturbances in real time, enhancing robustness to model uncertainties and external perturbations.

Extended state observer (ESO): A dynamic estimator within ADRC that reconstructs both system states and aggregated disturbances, enabling direct disturbance compensation in the control law.

Sliding mode control (SMC): A robust control technique that forces system trajectories onto a predefined sliding surface, offering insensitivity to matched uncertainties but requiring careful gain design to prevent chattering.

Self-aligning torque (SAT): The restoring moment generated by tyre–road interaction that returns the steering mechanism towards centre position, often treated as disturbance or exploited in advanced return-to-centre strategies.

References

1. Torque Control of Electric Power Steering Systems Based on Improved Active Disturbance Rejection Control. Mathematical Problems in Engineering (2020).
2. Research on active disturbance rejection control strategy of electric power steering system under extreme working conditions. Measurement and Control (2023).
3. Optimal Design of Fault‐Tolerant Controller for an Electric Power Steering System with Sensor Failures Using Genetic Algorithm. Shock and Vibration (2018).
4. Active Return-to-Center Control Based on Torque and Angle Sensors for Electric Power Steering Systems. Sensors (2018).