H-infinity Fuzzy Tracking Control and Its Application to Multibody Systems

• Main Authors: Chung-Shi Tseng, 曾仲熙
• Other Authors: Bor-Sen Chen
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/42023847237456117991

博士 === 國立清華大學 === 電機工程學系 === 89 === Recently, the nonlinear H-infinity control schemes have been introduced to deal with the robust performance design problem of nonlinear systems. However, the designer has to solve a Hamilton-Jacobi equation, which is a nonlinear partial differential equation. Only some very special nonlinear systems have a closed form solution. In general, conventional nonlinear H-infinity control schemes are not suitable for practical control system design. Based on the Takagi and Sugeno (TS) fuzzy model, both state feedback and output feedback decentralized fuzzy tracking control designs with a guaranteed H-infinity tracking performance will be addressed in this dissertation for a multi-arm system. A fuzzy observer-based control design will be employed to deal with the output feedback control problem. By the proposed method, the outcome of the fuzzy tracking control design problem can be parameterized in terms of a linear matrix inequality problem (LMIP) or an eigenvalue problem (EVP). The LMIP or EVP can be solved very efficiently using the convex optimization techniques. Systematical design procedure using LMI techniques is proposed to implement the H-infinity fuzzy tracking control problems. The results of the proposed H-infinity decentralized fuzzy tracking controller are applied to a multi-arm system. The main results are summarized as follows: First, this dissertation introduces a fuzzy control design method for nonlinear systems with a guaranteed H-infinity model reference tracking performance. First, the Takagi and Sugeno (TS) fuzzy model is employed to approximate a nonlinear system. Next, based on the fuzzy model, a fuzzy controller is developed to reduce the tracking error as small as possible for all bounded reference inputs. If the state variables are unavailable, a fuzzy observer-based tracking control design is also developed. The advantage of proposed tracking control design is that only a simple linear fuzzy controller is used in our approach without complicated feedback linearization technique and adaptive scheme. By the proposed method, the fuzzy tracking control design problem is parameterized in terms of a linear matrix inequality problem (LMIP). The LMIP can be solved very efficiently using the convex optimization techniques. Simulation examples are given to illustrate the design procedures and tracking performance of the proposed method. Second, it is not easy to design an H-infinity decentralized controller for nonlinear interconnected systems in general. In this dissertation, the tracking control problem of nonlinear interconnected systems is studied via H-infinity decentralized fuzzy control method. Similarly, the nonlinear interconnected system is represented by an equivalent Takagi-Sugeno type fuzzy model. A state feedback decentralized fuzzy control scheme is developed to achieve the H-infinity tracking performance. Furthermore, the stability of the nonlinear interconnected systems is also guaranteed. This design problem is equivalent to solving an eigenvalue problem (EVP). Third, due to the physical configuration and high dimensionality of the constrained multibody systems, a centralized fuzzy control is neither efficient nor even necessary. Therefore, a decentralized fuzzy control scheme is more suitable for the constrained multibody systems. In this dissertation, an H-infinity decentralized fuzzy tracking control scheme is proposed for a constrained multibody system. Finally, in order to illustrate the design effectiveness of the proposed H-infinity decentralized fuzzy tracking control scheme, an experimental multi-arm system with fully digital controller is setup to confirm the tracking performance.