Claes Olsson

Predictive Prevention of Loss of Vehicle Control for Roadway Departure Avoidance

In this paper, we investigate predictive approaches to the problem of roadway departure prevention via automated steering and braking. We assume a sensing infrastructure detecting road geometry and consider a two-layer accident avoidance framework consisting of a threat assessment and an intervention layer. A novel active safety function for prevention of loss of vehicle control is proposed and implemented using the considered accident avoidance framework. Simulation and experimental results are presented, showing that the proposed approach effectively exploits road preview information to prevent the vehicle from operating in regions of the state space where standard electronic stability control systems are normally activated.

Towards predictive yaw stability control

In this paper the possibility to predict vehicle loss of control using information about the host vehicles state and the road ahead is investigated. A threat assessment algorithm that predicts loss of control based on assumptions of the drivers future behavior is proposed. The algorithm can be used in an active safety system to motivate e.g. either earlier conventional yaw control interventions or completely autonomous maneuvers in order to keep the vehicle on the road. The algorithm has been experimentally tested and based on measurements it is shown that it is possible to predict powerful understeer situations if the future geometrical path of the vehicle is known.

Real-time implementation of a novel safety function for prevention of loss of vehicle control

We present a novel safety function for prevention of vehicle control loss. The safety function overcomes some of the limitations of conventional Electronic Stability Control (ESC) systems. Based on sensor information about the host vehicles state and the road ahead, a threat assessment algorithm predicts the future evolution of the vehicles state. If the vehicle motion, predicted over a finite time horizon violates safety constraints, autonomous deceleration is activated in order to prevent vehicle loss of control. The safety function has been implemented in real-time. Experimental results indicate that the safety function relies less on the drivers skills than conventional ESC systems and that a more controllable and comfortable vehicle motion can be acquired when the function is active.

Saturation-induced limit cycles in observer-based state feedback control

Abstract Existence of saturation-induced limit cycles is studied for observer-based state feedback control systems. Two different observer based controller implementations are considered, one using the computed control signal for state estimation and the other using the control signal actually applied to the plant. Based on piecewise affine system descriptions, analytical tools to conclude about limit cycles and exponential closed loop stability are provided for both implementations. The condition for limit cycles is found to involve the yet unsolved problem of spectral radius characterization of the product of two matrix exponentials.