1. Nonlinear Adaptive Control and Robust Control
Almost all practical systems are nonlinear, contain uncertainties, and are subjected to disturbances and delays, some of which can be modeled by ordinary differential equations (ODEs), some of which by differential-algebraic equations (DAEs), and some of which even do not have any mathematical models. My research work lies in control design for nonlinear systems described by either ODE or DAE or nonlinear systems with no model. Several different methodologies are used to deal with nonlinearities, uncertainties, delays, and un-modeled dynamics, which includes feedback linearization, backstepping, sliding-mode, fuzzy logic, neural network, etc. Robust and/or adaptive controllers can be designed with these methods.
2. Mobile Robots and Parallel Robots
As applications of robust and/or adaptive control theories to practical systems, biped robots and parallel robots are selected as objects to be controlled. The reason for this selection is that parallel robots can be modeled with nonlinear DAEs and biped robots are very complicated in terms of modeling and control. The modeling of biped robots involves both nonlinear ODEs for single support phase and nonlinear DAEs for double support phase. The control problems for biped robots include several aspects, such as trajectory planning, trajectory tracking, balance control, and so on. A tank robot is selected as a test-bed for implementing navigation algorithms with aid of image signals from camera on board. On the other hand, parallel robots and mobile robots have wide applications in industries.