Robust Vehicle Stability Control Based on Sideslip Angle Estimation

Vehicle stability control is very important to vehicle active safety, in particular, during severe driving manoeuvres. The yaw moment control has been regarded as one of the most promising means of vehicle stability control, which could considerably enhance vehicle handling and stability (Abe, 1999; Mirzaei, 2010). Up to the date, different strategies on yaw moment control, such as optimal control (Esmailzadeh et al., 2003; Mirzaei et al., 2008), fuzzy logic control (Boada et al, 2005; Li & Yu 2010), internal model control (IMC) (Canale et al., 2007), flatness-based control (Antonov et al, 2008), and coordinated control (Yang et al, 2009), etc., have been proposed in the literature. It is noticed that most existing yaw moment control strategies rely on the measurement of both sideslip angle and yaw rate. However, the measurement of sideslip angle is hard to be done in practice because the current available sensors for sideslip angle measurement are all too expensive to be acceptable by customers. To implement yaw moment controller without increasing too much cost on a vehicle, the estimation of sideslip angle based on measurement available signals, such as yaw rate and lateral acceleration, etc., is becoming necessary. And, the measurement noise should also be considered so that the estimation based controller is more robust. On the other hand, most of the existing studies use a linear lateral dynamics model with nominal cornering stiffness for the yaw moment controller design. Since the yaw moment control obviously relies on the tyre lateral force and the tyre force strongly depends on tyre vertical load and road conditions which are very sensitive to the vehicle motion and the environmental conditions, the tyre cornering stiffness must have uncertainties. Taking cornering stiffness uncertainties into account will make the controller being more robust to the variation of road conditions. In addition, actuator saturation limitations resulting from some physical constraints and tyre-road conditions must be considered so that the implementation of the controller can be more practical. In this chapter, a nonlinear observer based robust yaw moment controller is designed to improve vehicle handling and stability with considerations on cornering stiffness uncertainties, actuator saturation limitation, and measurement noise. The yaw moment