Abstract
-
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.