Marcus Börner

Model based fault detection of vehicle suspension and hydraulic brake systems

In modern vehicles, mechatronic systems are increasingly used. To improve reliability, safety and economy, an early recognition of small or drifting faults is becoming increasingly important. After a short introduction to methods of model based fault detection and diagnosis, application examples for fault detection of automotive vehicle suspension and hydraulic brake systems are given.

DETECTION OF LATERAL VEHICLE DRIVING CONDITIONS BASED ON THE CHARACTERISTIC VELOCITY

Abstract Using real-time and online models in vehicle control and fault diagnosis necessitates knowledge about time variant physical parameters and current driving situation. Detailed information about vehicle conditions, in form of a Characteristic Velocity Stability Indicator, is used to select the corresponding vehicle model structure for adaptive drive dynamic control. After a short introduction to a lateral vehicle model, a new approach for the online calculation of different driving conditions (i.e. stability, understeering, oversteering, and neutralsteering) is given.

Supervision, fault detection, and sensor fault tolerance of passenger cars

Abstract In the not too distant future, driver assistance systems (like a collision avoidance system) need more and more accurate infonnation about the current vehicle driving situation. This information can be obtained by a driver situation supervision system. This supervision unit can then be used as driver warning system or for new vehicle control algorithms. After a short introduction to a lateral vehicle model, a deterministic approach for the online calculation of different driving conditions (i.e. stability, understeering, oversteering, and neutralsteering) is given. But, driver assistance systems also need reliable sensor infonnation for decision-making. A presented sensor fault detection and fuzzy logic fault diagnosis system can classify 14 different faults. the fault type, fault location and fault cause. In the case of a faulty sensor signal, a reconfiguration of the sensor system is done by a sensor fault tolerance system. Real test-drives were done to verify the results physically.

The characteristic velocity stability indicator for passenger cars

Driver assistance systems have received increased attention as market demands have pushed for improved automotive safety. These systems are designed to aid the driver by preventing any unstable or unpredictable vehicle behaviour. One global indicator for stability and driving conditions could help to manage the control algorithms and driver warning subroutines. Another problem which could be solved by a precise driving situation indicator is evaluating new vehicles during test drives. After a short introduction to a linear lateral vehicle model, an analytical approach for an online calculation of different driving conditions (i.e., stability, understeering, oversteering, and neutralsteering) is given. A characteristic velocity stability indicator is defined, which allows online computation of the present driving condition. Results are then checked against real measurements of a test vehicle.

Model-Based Supervision and Control of Lateral Vehicle Dynamics

Abstract The further improvement of drive dynamic control needs model-based concepts. Two model-based applications are described. Firstly, the one-track model is used to indicate critical driving situations like oversteering or unstable behavior. Experiments with a middle-class vehicle show the results of this supervision and fault detection method. Secondly, it is shown by simulation how the understeering and oversteering behavior can be influenced by anti-roll bar actuation. Then a nonlinear yaw-rate controller for active steering is designed and it is shown by simulation how the steering behavior can be improved by anti-roll actuation.

Fault Detection for Lateral and Vertical Vehicle Dynamics

Abstract Mechatronic systems for vehicles have received increased importance for improving automotive safety and comfort. These systems are designed to aid the driver by preventing unstable or unpredictable vehicle behavior and to stabilize the horizontal and vertical motion of the vehicle. This is achieved by the integration of actuators, sensors and data processing. However, the attained benefits are paralleled by an increase in the complexity of the system requiring enhanced methods for fault detection and diagnosis. Therefore, concepts for model-based fault detection and diagnosis along with sensor fault tolerance are presented and realized for both a vehicle lateral dynamics system and an active suspension system.

Control of Mechatronic Semi-Active Vehicle Suspensions

Abstract After discussing the various principles of suspensions with variable dampers and springs mathematical models of these systems are derived. It is shown how the unknown parameters can be obtained experimentally by parameter estimation. Then two feedback principles are derived for controlling the suspension. The first controller maintains the suspension adjustment by parameter estimation and parameter control in one loop. The second controller exists of an adaptive minimum variance controller ensuring a permanent optimal performance. Experimental results are shown for suspensions on a test rig.

Characteristic Velocity Stability Indicator for Passenger Cars

Abstract A precise knowledge about the current driving condition is getting increasingly important for future driver assistance systems to support the prevention of any critical driving situation. Moreover a precise knowledge about the driving situation can be used in testing and comparing new passenger cars. After a short introduction of a lateral vehicle model, an analytical approach for an online calculation of different driving conditions (i.e. stability, understeering, oversteering, and neutralsteering) is given. A characteristic velocity stability indicator is defined, which allows on-line computation of the present driving condition Real test-drives show the application.

Online detection of tyre pressure deflation in passenger cars

Abstract Monitoring of tyre a pressure in passenger vehicle is a major aspect of improved active vehicle safety. In this contribution, a new velocity compensated method for monitoring tyre pressure using vertical body acceleration signals is presented. It is found that the wheel hop frequency is strongly correlated with damping coefficient and nature of road excitation. Limitations of using the shift of wheel hop frequency are presented. To avoid the influence of nature of road excitation, a virtual transfer function has been derived between front and rear body acceleration signals based on certain predefined event of the vehicle. The delay in transfer function is strongly related to velocity of the vehicle. The characteristic features are generated from the frequency response of the virtual transfer function. The sensitivity analysis presents the effects of the variation of mass of the vehicle and the spring stiffness has no effect on the frequency response but the damping coefficient has an influence. A simple threshold is found from experiment data for classification of relative tyre deflation. The tyre pressure diagnostic algorithm is implemented online and tested for different relative tyre pressure deflations.

Trajectory prediction for vehicle driver assistance systems

Abstract Future driver assistance systems (like a collision avoidance system) need accurate information about the current vehicle driving situation and an accurate prediction of admissible driving trajectories. After a short introduction to a vehicle model, an approach to calculate the set of admissible driving trajectories is presented. Each driving trajectory is judged by the Characteristic Velocity Stability Indicator CVSI to obtain admissible trajectories. Different sets of admissible driving trajectories are shown for variations of friction between tire and road, steering wheel input and velocity.