Graphical stability analysis for a fuzzy PID controlled robot arm model

Describes a graphical approach to stability analysis for a two-link flexible-joint robot arm model controlled by a fuzzy proportional-integral-derivative (PID) controller developed by the present authors. This new fuzzy PID controller preserves the simple linear structure of its conventional counterpart yet enhances its self-tuning control capability, thereby significantly improving tracking control performance. A simulation result on a two-link flexible-joint robot arm model is included to visualize such satisfactory performance. A simple and realistic sufficient condition for the stability of the overall feedback control system is then derived from a graphical approach, giving a safe region for design, on which the fuzzy PID controlled robot arm system have guaranteed stability