Distributed Sensing and Observer Design for Vehicles State Estimation
Loading...
Date
2009-06-16T13:25:24Z
Authors
Bolandhemmat, Hamidreza
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
A solution to the vehicle state estimation problem is given using the Kalman filtering and the Particle filtering theories. Vehicle states are necessary for an active or a semi-active suspension control system, which is intended to enhance ride comfort, road handling and stability of the vehicle. Due to a lack of information on road disturbances, conventional estimation techniques fail to provide accurate estimates of all the required states. The proposed estimation algorithm,
named Supervisory Kalman Filter (SKF), consists of a Kalman filter with an extra update step which is inspired by the particle filtering technique. The extra step, called a supervisory layer, operates on the portion of the state vector that cannot be estimated by the Kalman filter. First, it produces N randomly generated state vectors, the particles, which are distributed based on the Kalman filter’s last updated estimate. Then, a resampling stage is implemented to collect the
particles with higher probability. The effectiveness of the SKF is demonstrated by comparing its estimation results with that of the Kalman filter and the particle filter when a test vehicle is passing over a bump. The estimation results confirm that the SKF precisely estimates those states of the vehicle that cannot be estimated by either the Kalman filter or the particle filter,
without any direct measurement of the road disturbance inputs.
Once the vehicle states are provided, a suspension control law, the Skyhook strategy,
processes the current states and adjusts the damping forces accordingly to provide a better and safer ride for the vehicle passengers. This thesis presents a novel systematic and practical methodology for the design and implementation of the Skyhook control strategy for vehicle’s
semi-active suspension systems. Typically, the semi-active control strategies (including the Skyhook strategy) have switching natures. This makes the design process difficult and highly dependent on extensive trial and error. The proposed methodology maps the discontinuous
control system model to a continuous linear region, where all the time/frequency design
techniques, established in the conventional control system theory, can be applied. If the semiactive control law is designed to satisfy ride and stability requirements, an inverse mapping offers the ultimate control law. The effectiveness of the proposed methodology in the design of a semi-active suspension control system for a Cadillac SRX 2005 is demonstrated by real-time
road tests. The road tests results verify that the use of the newly developed systematic design methodology reduces the required time and effort in real industrial problems.
Description
Keywords
Vehicles State Estimation, Systems with Unknown Inputs/Disturbances, Kalman Filtering, Unscented Kalman Filtering, Bayesian Estimation and Particle Filtering, Real-time Experiments