Chang-Ho Hyun

Takagi-Sugeno fuzzy model based indirect adaptive fuzzy observer and controller design

This paper proposes the design scheme of the alternative adaptive observer and controller based on the Takagi-Sugeno (T-S) fuzzy model. The T-S fuzzy modeling and the state feedback control technique are adopted for the simple structure. The proposed method maintains consistent performance in the presence of parameter uncertainties and incorporates linguistic fuzzy information from human operators. In addition, with the simple adaptive state feedback controller, it solves the singularity problem, which occurs in the inverse dynamics based on the feedback linearization method. Using Lyapunov theory and Lipschitz condition, the stability analysis is conducted, and the adaptive law is derived. The proposed method is applied to the stabilization problem of a flexible joint manipulator in order to guarantee its performance.

Design of sliding-mode control based on fuzzy disturbance observer for minimization of switching gain and chattering

In this paper, we propose the sliding mode control (SMC) based on the fuzzy disturbance observer for systems with disturbances to minimize the switching gain and reduce chattering phenomenon. The proposed method exhibits the following two attractive features. First, using the universal approximation and the adjustable parameter of the fuzzy system, the switching gain in proposed control law is only required to be designed greater than the sum of magnitude of the disturbance approximation error and the fuzzy reconstruction. It implies that the proposed controller is less dependent on the range of switching gain to stabilize the system than SMC; thus, the minimization of switching gain can reduce the chattering. Second, the proposed method exhibits much better control performance than the traditional SMC and Nonlinear Disturbance Observer (NDOB)-based SMC, such as reduced chattering and good performance. The stability of the proposed control system is proved using Lyapunov method. To verify the effectiveness of the minimization of switching gain and chattering, we show the performance of the proposed method through some simulations of the inverted pendulum.

Robust Tracking Control Using Fuzzy Disturbance Observer for Wheeled Mobile Robots with Skidding and Slipping

This paper proposes a robust tracking controller based on the Fuzzy Disturbance Observer (FDO) for a Wheeled Mobile Robot (WMR) with unknown skidding and slipping. The proposed method provides disturbance-free techniques for stability analysis. In our previous work [1], we proposed an extended state-observer approach to robust tracking control for wheeled mobile robots with skidding and slipping. Even though satisfying performances were shown and the proposed method was verified in [1], the derivatives of disturbance should go to zero as time passes in order to guarantee performance. This is a very critical assumption. The method proposed in this paper overcomes this problem using universal approximation with a fuzzy model. Thus, the condition that disturbance should disappear with time is not required anymore. Furthermore, the proposed method can be used more widely than that shown in the previous work. This is guaranteed by a Lyapunov-theory-based stability analysis, and performance is verified by simulation results.

Robust dynamic surface tracking control for uncertain wheeled mobile robot with skidding and slipping

This paper proposes a robust dynamic surface control (DSC) tracking method for wheeled mobile robots (WMRs) with skidding and slipping. First, a simple WMRs model is derived. This model has the simple structure to handle not only kinematics but also dynamics. Then, a tracking controller is proposed by using the DSC method. The proposed method eliminates the complexity problem in the traditional backstepping design. In addition, we use the idea of nonlinear damping in order to cancel out the disturbances. Finally, numerical simulations are included to illustrate the validity of the proposed.