Steering Feedback Transparency Using Rack Force Observer
Preprint, 2021

Closed-loop electric power assisted steering and steer-by-wire systems are non-transparent towards the environment dynamics, i.e. the tire-road interaction. To achieve the driver-environment transparency, an estimate of the environment interaction through the rack force is required. With an introduction of the dynamic rack force observer feedback, a closed-loop interconnection is formed. Hence, stability must to be ensured.

At first, a driver coupled stability condition is derived to obtain the maximum achievable transparency for a passive environment port in different control architectures. Then, a non-linear rack force observer is proposed and implemented for transparency. Two estimation methods are compared: (a) using the body motion signals from the inertial measurement unit sensor; and (b) using the steering system sensors. Experiments indicate that the former estimation method has an inferior performance due to vehicle inertial properties. Whereas with the latter approach, the inclusion of higher order dynamics and a non-linear estimation algorithm shows a noticeable improvement.

Finally, experiments on a real electric power assisted steering hardware illustrate the proposed steering feedback transparency, when driving at the limits of handling.

torque/position control

Haptic feedback

steering system

passivity

real-time estimation

transparency

Author

Tushar Chugh

Chalmers, Mechanics and Maritime Sciences, Vehicle Engineering and Autonomous Systems

Fredrik Bruzelius

Chalmers, Mechanics and Maritime Sciences, Vehicle Engineering and Autonomous Systems

Matthijs Klomp

Chalmers, Mechanics and Maritime Sciences, Vehicle Engineering and Autonomous Systems

Bengt J H Jacobson

Chalmers, Mechanics and Maritime Sciences, Vehicle Engineering and Autonomous Systems

Steer by wire Opportunities, performance and system safety (SWOPPS)

VINNOVA (2017-05504), 2018-03-09 -- 2021-07-01.

Areas of Advance

Transport

Subject Categories

Vehicle Engineering

Control Engineering

Other Electrical Engineering, Electronic Engineering, Information Engineering

More information

Created

6/13/2021