Hyoun-Chul Choi

Hybrid control for longitudinal speed and traction of vehicles

This paper presents a hybrid system approach to longitudinal speed and traction control of a vehicle with wheel slip constraints. The vehicle system is modeled as a hybrid system where the system is divided into local subsystems and each subsystem is selected to control the vehicle, in terms of control modes and operating region. Controllers are designed to track a desired speed value while maintaining the safety constraint that the absolute value of the slip between wheels and ground must be less than a given limit value to prevent the wheels from skidding or spinning. Simulation results are provided to show the feasibility of the proposed control system.

Guaranteed Cost Control of Uncertain Systems Subject to Actuator Saturation

In this paper, the problem of guaranteed cost control (GCC) for some classes of uncertain nonlinear systems is considered. In particular, the paper considers the problem of GCC for uncertain systems subject to actuator saturation and proposes an LMI-based condition for GCC design, which admits norm-bounded uncertainties and some classes of nonlinearities. The resulting LMI condition is further used for solving a convex optimization problem which minimizes the upper-bound of a cost function associated with the given systems. The solution leads to a state-feedback controller that minimizes the upper-bound of the cost function in the presence of uncertainties and actuator saturation. The effectiveness and applicability of the proposed method is illustrated by simulation examples

Fuzzy angular velocity control of mobile robots using vision system in a corridor

This paper proposes a vision-based simple fuzzy angular velocity control method for mobile robots with vision system in a corridor. To this end, visual information from the camera is obtained as vanishing point and middle point. They are employed for collision free navigation in the corridor. To control the mobile robot in the corridor using vision system, we generate the kinematic model of the system from the image directly, and design the simple fuzzy controller using vanishing point and middle point. The simulation results are included to demonstrate the validity of the proposed method.

H∞ Control of T-S Fuzzy Systems Using a Fuzzy Basis- Function-Dependent Lyapunov Function

This paper proposes an controller design method for Takagi-Sugeno (T-S) fuzzy systems using a fuzzy basis-function-dependent Lyapunov function. Sufficient conditions for the guaranteed performance of the T-S fuzzy control system are given in terms of linear matrix inequalities (LMIs). These LMI conditions are further used for a convex optimization problem in which the of the closed-loop system is to be minimized. To facilitate the basis-function-dependent Lyapunov function approach and thus improve the closed-loop system performance, additional decision variables are introduced in the optimization problem, which provide an additional degree-of-freedom and thus can enlarge the solution space of the problem. Numerical examples show the effectiveness of the proposed method.

[ H 2 ] Control of Uncertain Systems with Actuator Saturation

This paper presents an LMI-based method to design a saturated state-feedback controller for uncertain systems with actuator saturation. Specifically, the paper proposes a sufficient condition such that the system under norm-bounded uncertainties and actuator saturation is asymptotically stable and the -norm of the system has an upper-bound. The resulting condition is further utilized to solve a convex optimization problem specified in the context of -norm minimization, whose solution yields a saturated controller. A numerical example is presented to show the effectiveness of the proposed method.

Swing-up and stabilization control of a two-links rotational pendulum

A strategy for the swing-up and stabilization control method for a two-links rotational pendulum according to states of each link of the rotational pendulum is proposed. The proposed controller consists of two modes of control such as divergence mode and stabilization mode. When the controller is in divergence mode, control input is generated using sinusoidal function, which is developed based on resonance period of the pendulum in the linear region, to make the second link (pendulum) reach top position. After the controller finishes operation in divergence mode, stabilization control is initiated to keep the pendulum around the top position using the linear quadratic (LQ) control method. Experimental results are given to show the effectiveness of the proposed method.