Chapter 6 - Mechatronic Design of Flexible Manipulators

Abstract

The construction of lightweight manipulators with a larger speed range is one of the major goals in the design of well-behaved industrial robotic arms. Their use will lead to higher productivity and less energy consumption than is common with heavier, rigid arms. However, due to the flexibility involved with link deformation and the complexity of distributed parameter systems, modeling and control of flexible manipulators still remain a major challenge in robotic research. A compromise between modeling costs and control efficiency for real-time implementation is inevitable. The interdependency of subsystems results in a local optimal performance in the traditional design scheme. An important research topic in flexible manipulator design is the pursuit of better system performance while avoiding model-intensive or control-intensive work. This problem can be solved using the proposed mechatronic design approach. It treats the mechanical, electrical, and control components of a flexible manipulator concurrently. The result is a global optimal design with an explicit link shape and controller parameters that result in the control problem and modeling accuracy no longer being critical for obtaining desired performance, with the coupling effects among subsystems being taken into account automatically. Dynamics of flexible manipulators with shear force and rotary inertia are derived, and state-space equations with the integration of DC motor dynamics are developed as a theoretical basis for mechatronic designs. Case studies based on LQR formulas and H ∞ are considered. The beam shape and controller parameters are obtained using an adaptive iterative algorithm with the accommodation of various geometrical constraints. Also, different output feedback strategies are investigated to evaluate the impacts of various controller structures.