A novel observer design for simultaneous estimation of vehicle steering angle and sideslip angle

Both steering angle and sideslip angle are

important states for vehicle handling and stability control.

Instead of directly measuring these angles, indirect estimation

of these states will provide a cost-effective way for

the implementation of vehicle control systems. In the past,

model-based methods have been proposed to estimate the

sideslip angle with the measured steering angle. In this

paper, a novel observer design is presented for simultaneous

estimation of vehicle steering angle and sideslip angle

so that the estimation of sideslip angle does not require the

measurement of steering angle and the estimate of steering

angle can also be used for other purposes, such as automatic

steering control, steering system fault diagnosis, and

driving performance monitoring. To enable this observer

design, the Takagi–Sugeno (T–S) fuzzy modeling technique

is applied to represent the vehicle lateral dynamics

model with nonlinear Dugoff tyre model and time-varying

vehicle speed. A T-S observer is then designed to simultaneously

estimate the steering angle and sideslip angle

with the measurements of yaw rate and vehicle speed, and

is designed to be robust against parameter uncertainties

and unknown inputs. The conditions for designing such

an observer are derived in terms of linear matrix inequalities

(LMIs). Experimental results are used to validate the

effectiveness of the proposed approach. The results show

that the designed observer can effectively estimate steering

angle and sideslip angle despite the variation of vehicle

longitudinal speed.