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This paper presents a physically intuitive method for altering a vehicle's handling characteristics through active steering intervention. A full state feedback controller augments the driver's steering command via steer-by-wire to achieve desired handling behavior. Accurate estimates of vehicle states are available from a combination of Global Positioning System (GPS) and Inertial Navigation System (INS) sensor measurements. By canceling the effects of steering system dynamics and tire disturbance forces, the steerby-wire system is able to track commanded steer angle with minimal error. Experimental results verify that with precise steering control and accurate state information, a vehicle's handling characteristics can be modified to match driver preference or to compensate for changes in operating conditions.

This paper demonstrates a method of estimating several key vehicle states—sideslip angle, longitudinal velocity, roll and grade—by combining automotive grade inertial sensors with a Global Positioning System (GPS) receiver. Kinematic Kalman filters that are independent of uncertain vehicle parameters integrate the inertial sensors with GPS to provide high update estimates of the vehicle states and the sensor biases. Using a two-antenna GPS system, the effects of pitch and roll on the measurements can be quantified and are demonstrated to be quite significant in sideslip angle estimation. Employing the same GPS system as an input to the estimator, this paper develops a method that compensates for roll and pitch effects to improve the accuracy of the vehicle state and sensor bias estimates. In addition, calibration procedures for the sensitivity and cross-coupling of inertial sensors are provided to further reduce measurement error. The resulting state estimates compare well to the results from calibrated models and Kalman filter predictions and are clean enough to use in vehicle dynamics control systems without additional filtering.

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