Rack force estimation from standstill to high speeds by hybrid model design and blending

Steer-by-wire (SbW) is the latest steering evolution, providing many benefits, such as reduced vehicle weight and enhanced steering capability. While reliability is one of the main concerns hindering its widespread application, the potential of this technology to revolutionize the automotive industry is huge. Control techniques play an important part in achieving the full potential of SbW by focusing on the development of its performance and safety aspects. This paper provides a review of the control techniques that are being used in SbW technology to achieve better performance and enhance safety. Various control techniques for SbW exist to serve different purposes when dealing with the non-linear nature of the SbW dynamics. Although there is no one-size-fits-all control technique for all the requirements of the SbW, this study highlights that the non-linear controllers based on the sliding mode control (SMC) are a popular option for enhancing the accuracy of SbW systems. However, these controllers often suffer from a downside known as chattering. In contrast, robust controllers like Model Predictive Controllers (MPCs) can effectively manage uncertain dynamics and eliminate chattering, although they pose challenges due to their high computational costs.

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Steer-by-Wire: Universal Calculation of Production-Dependent, Strongly Fluctuating Friction in Steering

Schäfer,

Leidhold,

Achilles

2023

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">In steer-by-wire (SbW) vehicles, understanding the steering rack force is essential to replicate a realistic steering feel, allowing conclusions to be drawn about road surface conditions by the decoupled manual actuator. Since internal friction varies with each steering system manufactured and installed, these models differ greatly in accuracy. This paper presents a concept for continuously calculating fluctuating friction based on the internal steering variables to avoid additional and complex individual measurements. An SbW system offers the right approach by adjusting the driver’s desired steering angle and the required motor control. The underlying steering clearance and the Kalman filter are used to calculate the steering rack force. The validity of the proposed concept is shown in drive tests according to ISO 13674 and ISO 7401 to gauge high and low friction values in different speed ranges.</div></div>

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Rack force estimation from standstill to high speeds by hybrid model design and blending

Cited by 3 publications

References 13 publications

Sensitivity-Based Moving Horizon Estimation of Road Friction

Sensitivity-Based Moving Horizon Estimation of Road Friction

Control Strategies for Steer-By-Wire Systems: An Overview

Steer-by-Wire: Universal Calculation of Production-Dependent, Strongly Fluctuating Friction in Steering

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