Shahab Sheikholeslam

Automated vehicle control developments in the PATH program

The accomplishments to date on the development of automatic vehicle control technology in the Program on Advanced Technology for the Highway (PATH) at the University of California, Berkeley, are summarized. The basic principles and assumptions underlying the PATH work are identified, and the work on automating vehicle lateral (steering) and longitudinal (spacing and speed) control is explained. For both lateral and longitudinal control, the modeling of plant dynamics is described, and the development of the additional subsystems needed (communications, reference/sensor systems) and the derivation of the control laws are presented. Plans for testing on vehicles in both near and long term are discussed. >

Longitudinal control of a platoon of vehicles with no communication of lead vehicle information: a system level study

The paper considers the problem of longitudinal control of a platoon of automotive vehicles on a straight lane of a highway and proposes control laws in the event of loss of communication between the lead vehicle and the other vehicles in the platoon. After discussing the main design objectives for the proposed control laws, the authors formulate these objectives as a constrained optimization problem. By solving this optimization problem, they obtain longitudinal control laws for a platoon of vehicles which does not use any communication from the lead vehicle to the other vehicles in the platoon. Comparison between these control laws and the control laws which use such a communication link to transmit lead-vehicle information to the other vehicles in a platoon shows that, in the case of loss of communication between the lead vehicle and the other vehicles, the performance of the longitudinal control laws degrades; however, this degradation is not catastrophic. >

A System Level Study of the Longitudinal Control of a Platoon of Vehicles

This paper presents a preliminary system study of a longitudinal control law for a platoon of nonidentical vehicles using a simplified nonlinear model for the vehicle dynamics. This study advances the art of automatic longitudinal control for a platoon of vehicles in the sense that is considers longer platoons composed of nonidentical vehicles; furthermore, the longitudinal control laws presented in this study take advantage of communication possibilities not available in the recent past

Control of interconnected nonlinear dynamical systems: the platoon problem

The problem to be solved involves a highway automation project. The overall system consists of N vehicles (the platoon). Each vehicle is driven by the same input u and the state of the kth vehicle affects the dynamics of the (k+1)th vehicle. Furthermore, the dynamics of each vehicle is affected by its (local) state-feedback controller. Under very general conditions, it is shown that for sufficiently slowly varying inputs, decentralized controllers can be designed so that the platoon maintains its cohesion. >

Indirect adaptive control of a class of interconnected non-linear dynamical systems

We consider the class of interconnected non-linear dynamic systems suggested by the problem of longitudinal and lateral control of a platoon of vehicles on automated highways. After describing the physical setting from which the control problem arises, we propose a local indirect adaptive control scheme for this class of interconnected non-linear systems. Then, we establish that the proposed local adaptive control scheme is suitable for monotonically decreasing the magnitude of deviations of each dynamic systems state from its sink manifold provided that (a) the exogenous input is varying sufficiently slowly and (b) the parameter error is sufficiently small. As a consequence, these deviations are bounded with a bound independent of the number of subsystems in the interconnection.

Design of decentralized adaptive controllers for a class of interconnected nonlinear dynamical systems

The authors consider a class of interconnected nonlinear dynamical systems suggested by the problem of longitudinal control of a platoon of vehicles on a lane of a highway. After describing the physical setting from which the control problem arises they propose a decentralized adaptive control scheme for this class of system. They establish that the proposed adaptive control scheme is suitable for monotonically decreasing the bound on the magnitude of deviations of each dynamical systems state from its sink manifold provided that the exogenous input is varying sufficiently slowly and the state-observer error is sufficiently small. An important feature of this adaptive control scheme is that these deviations are bounded independently of the parameter errors.<<ETX>>

Control of an interconnection of nonlinear dynamical systems

The problems encountered in a highway automation project are considered. The overall system consists of N+1 vehicles (the platoon); each vehicle is driven by the same input, and the state of the k-th vehicle affects the dynamics of the (k+1)-th vehicle; furthermore, the dynamics of each vehicle is affected by its (local) state-feedback controller. Under very general conditions, it is shown that, for sufficient slowly varying inputs, the local feedbacks can be designed so that the platoon maintains its cohesion.<<ETX>>

Observer-Based Parameter Identifiers for Nonlinear Systems with Parameter Dependencies

We consider the class of nonlinear dynamical systems whose dynamics depends linearly on the unknown parameter vector. After reviewing a standard observer-based identifier for estimating the unknown parameters, we propose a family of new identifiers which exploit the a priori known parameter dependencies. Then, we establish that, under mild assumptions on the dynamical system, a) the proposed identifiers are stable, and b) the weighted norm of state-parameter errors using the proposed identifiers are less than the corresponding errors using the standard identifier, for a length of time after t = 0. The main contribution of this paper is that it introduces a family of observer-based identifiers which exhibit better transient performance than the standard identifier.