Mixed Slip-Deceleration Control in Automotive Braking Systems

Abstract

In road vehicles, wheel locking can be prevented by means of closed-loop anti-lock braking systems (ABS). Automatic braking is extensively used also for electronic stability control (ESC) systems. In braking control systems, two output variables are usually considered for regulation purposes: wheel deceleration and wheel longitudinal slip. Wheel deceleration is the controlled output traditionally used in ABS, since it can be easily measured with a simple wheel encoder; however, the dynamics of a classical regulation loop on the wheel deceleration critically depend on the road conditions. A regulation loop on the wheel longitudinal slip is simpler and dynamically robust; moreover, slip control is perfectly suited for both ABS and ESC applications. However, the wheel-slip measurement is critical, since it requires the estimation of the longitudinal speed of the vehicle body, which cannot be directly measured. Noise sensitivity of slip control hence is a critical issue, especially at low speed. In this work a new control strategy called mixed slip-deceleration (MSD) control is proposed: the basic idea is that the regulated variable is a convex combination of wheel deceleration and longitudinal slip. This strategy turns out to be very powerful and flexible: it inherits all the attractive dynamical features of slip control, while providing a much lower sensitivity to slip-measurement noise.

Wheel Slip Control for Improving Traction-Ability and Energy Efficiency of a Personal Electric Vehicle

“…Additionally, the asymptotic stability property and robustness are discussed by employing the Lyapunov stability method. Sliding mode control techniques have been widely used in vehicle dynamics control systems such as anti-lock braking systems, yaw stability control systems, and traction control systems due to their strong robustness [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Since the vehicles operate under a wide range of speed and road conditions, the vehicle controllers should provide robustness against varying parameters and undesired disturbances over all the driving regions.…”

Stabilization of Automotive Vehicles Using Active Steering and Adaptive Brake Control Allocation

“…Many different wheel slip control strategies can be found in the literature; see for example the mixed slip-deceleration approach from [26], Lyapunov based solutions [10], [40] and [18], sliding-mode based controllers [7], [39] and [27] and PID approaches [30], [16] and [29]. Here we consider a standard Lyapunov approach with adaptation and feed-forward which allows a straight forward use of the dynamic control allocation result from [33].…”

Real-time identification of tire–road friction conditions

“…More precisely, as far as the expected performances are concerned, the aim is to obtain an overall accuracy in the estimation of the abscissa of the peak of the friction curve of +5%, which is considered appropriate for ABS control [21]. Furthermore, the estimator should provide reliable information within the time instant at which the ABS would be activated.…”