Machining, Measurement, and Control Laboratory

Design of Luenberger State Observers using Fixed-structure H-infinity Optimization and Its Application to Fault Detection in Lane-Keeping Control of Automated Vehicles
Soichi Ibaraki, Shashikanth Suryanarayanan, Masayoshi Tomizuka

Lane-keeping control forms an integral part of fully-automated Intelligent Vehicle Highway Systems (IVHS). Therefore, its reliable operation is critical to the operation of an automated highway. In this paper, we present the design of a fault detection filter for the lane-keeping control systems on-board vehicles used by California-PATH, USA in its automated highways program. We use a Luenberger structure for the fault detection filters and tune the observer gains based on an H-infinity based cost. Such a choice of cost was motivated by the need to explicitly incorporate frequency domain based performance objectives. The LMI-based formulation of an H-infinity optimization problem of Luenberger state observers does not allow for the augmentation with dynamic performance weightings in the optimization objective, since it makes the problem a non-convex optimization problem. We present an algorithm to locally solve the problem of design of Luenberger state observers using H-infinity optimization by transforming the problem into an H-infinity static output feedback controller problem. Experimental results demonstrate the efficacy of the tuning methodology by comparing the fault detection performance of filters that use H-infinity Luenberger observers versus those that use Kalman Filters. Implementation issues of the observers are also discussed.
Key Words:   State estimation, H-infinity Optimization, Frequency shaping, Fault detection, Integrated Vehicle Highway Systems