Control, estimation, and communication design applied to active vehicle safety systems.

摘要

This thesis studies the joint design of control, estimation, and communication systems, focusing on their application to active vehicle safety systems. The active safety systems on-board a vehicle, such as collision avoidance systems, help the driver detect and defuse oncoming potential crash situations. They have received significant attention recently. Wireless communication and estimation are critical components of an active safety system enabling the vehicle to be aware of surrounding vehicles and the roadway. The information provided by the communication and estimation systems can be used by vehicle control systems such as Cooperative Adaptive Cruise Control (CACC) or driver assistance/warning systems.; This thesis makes advances in three areas---a benefit analysis of vehicle-vehicle communication-aided CACC system in highway traffic, the design of Medium Access Control (MAC) protocols for vehicle safety messaging over Dedicated Short Range Communication (DSRC); and the real-time estimation of a Markov process over a noisy digital communication channel.; We compare the influence of adaptive cruise control (ACC) and CACC systems on highway traffic behaviors. The main difference between the CACC systems and the ACC systems is that CACC systems have vehicles interact by exchanging information through communication. Communication is shown to decrease braking effort, increase average velocity, reduce congestion, and smooth shock waves. The positive results motivate us to design efficient communication and estimation systems for vehicle active safety system.; We next study the design of MAC protocols for vehicles to send safety messages to each other. The target is to send vehicle safety messages with high reliability and low delay. We propose and analyze several random access MAC protocols. The protocols are compatible with the national DSRC multi-channel architecture. Both analytical and simulation results show our approach is feasible for vehicle safety messages in DSRC. Our best protocol outperforms the popular standard IEEE 802.11 MAC protocol.; Finally, we study the real-time estimation of a Markov process over a memoryless noisy digital communication channel. The problem could model a vehicle estimating in real time the position, relative velocity, and direction of neighboring vehicles using the information obtained by wireless communication. We derive structural results on the optimal encoder and decoder are derived. A recursive algorithm is given to jointly find a locally optimal encoder and decoder for the binary symmetric channel. For a memoryless Gaussian vector source and a binary symmetric channel, we find the optimal policy and derive the minimum mean squared error as a function of the variance of the source and the channel noise.