Direct adaptive control for tendon-driven manipulators

The development and evaluation of both adaptive primary (inner-loop) and robust secondary (output-loop) model-based controllers is discussed. Previous case studies rigorously investigated the feasibility of implementing passivity-based inner-loop adaptation on an industrial manipulator. An unanswered question was the general validity of those results. The authors address that issue by repeating the analysis on a small serial robot with a pneumatic tendon drive system. Experimental analysis reverifies the algorithm´s adaptation/learning capabilities and provides new insight into how the implementation issues of tuning, and parameter convergence depend on specific manipulator structure. Direct adaptive control enhances trajectory tracking efficacy and reduces payload sensitivity for a wide range of manipulators