Bongsob Song

Development of a Collision Avoidance System

The analysis of a rear-end collision warning/ avoidance (CW/CA) system algorithm will be presented. The system is designed to meet several criteria: 1. System warnings should result in a minimum load on driver attention. 2. Automatic control of the brakes should not interfere with normal driving operation.

Robust stabilization and ultimate boundedness of dynamic surface control systems via convex optimization

In this paper, a new method of analysing the controller gains and filter time constants for dynamic surface control (DSC) is presented. First, since DSC provides linear error dynamics with perturbation terms for a class of non-linear systems, the design method can be used to assign the system matrix eigenvalues of the closed loop error dynamics. Then a procedure for testing the stability and performance of the fixed controller in the face of uncertainties is presented. Finally, an ellipsoidal approximation of the tracking error bounds for a tracking problem is obtained via convex optimization.

Fault tolerant control and classification for longitudinal vehicle control

In this paper a new method of analyzing for the performance loss caused by faults in the systems is presented, and applied to the design of a fault tolerant longitudinal controller for a transit bus. Based on the amount of performance loss measured by a quadratic function, fault impact assessment is developed for both single and multiple faults. More specifically, ellipsoidal approximation of the tracking error bounds via dynamic surface control (DSC) is obtained via convex optimization technique for the nonlinear closed-loop system. Relying on the fault impact to the closed loop system and its isolatability on a fault detection and diagnosis system, the fault classification is proposed to provide a switching logic in the framework of a switched hierarchical structure. Finally, simulation results of the fault tolerant controller and corresponding fault classification are shown for multiple multiplicative faults.

Dynamic surface control design for a class of nonlinear systems

A novel method for analyzing the controller gains and filter time constants of dynamic surface control (DSC) is presented. First, DSC provides linear closed loop error dynamics with bounded perturbation terms for a class of nonlinear systems. This can be used to assign the desired eigenvalues to the system matrix of the error dynamics for the nominal stability. Then, a procedure for testing the stability and performance of the fixed controller in the face of uncertainties is presented. Finally, a feasible quadratic Lyapunov function for a regulation problem and an ellipsoidal approximation of tracking error bounds are obtained via convex optimization.

Simultaneous quadratic stabilization for a class of non-linear systems with input saturation using dynamic surface control

In this paper, a new method to estimate the initial condition set which guarantees the quadratic stability for a class of non-linear systems via dynamic surface control (DSC) in the presence of input saturation has been proposed. The estimated set is enlarged to allow some degree of input saturation, while achieving the simultaneous quadratic stability of the system in the domain. A convex optimization problem to obtain ellipsoidal initial condition sets via a linear matrix inequality (LMI) approach as well as an illustrative example will be presented.

Cooperative Range Estimation and Sensor Diagnostics for Vehicle Control

An integrated sensor fusion and fault diagnostic for the cooperative estimation of range and range rate in automated vehicles is presented in this paper. A virtual range sensor created by combining local sensor measurements and a wireless communication link between vehicles is fused with measurements from a Doppler radar and lidar. The sensor fusion is conducted by using a sequential variant of the nonparametric probabilistic data association filter with validation gating. Fault diagnostics are incorporated into the sensor fusion by thresholding the Mahalanobis distance computed in the validation stage. Performance of the integrated system is verified and demonstrated using experimental data obtained from low-speed vehicle following tests.Copyright

Observer-based dynamic surface control for Lipschitz nonlinear systems

This paper presents a new analysis method to design an observer-based dynamic surface controller (ODSC) for a class of nonlinear systems. While the separation principle from linear system theory does not generally hold for nonlinear systems, a separation principle for the ODSC systems will be shown for a class of nonlinear systems, thus enabling the independent design of the observer and DSC. Furthermore, a convex optimization problem will be formulated to test the sufficient condition for quadratic stability of ODSC.

Constrained stabilization for a class of nonlinear systems using dynamic surface control

In this paper, a new method to estimate the initial condition set which guarantees the quadratic stability for a class of uncertain nonlinear systems via dynamic surface control (DSC) without control input saturation has been studied. The set can be enlarged to allow some degree of the control input saturation, while preserving the quadratic stability of the system in the domain. An algorithm to obtain ellipsoidal initial condition sets via a linear matrix inequality (LMI) approach as well as an illustrative example will be presented.