Control Theory for Nonlinear, Distributed, Mechatronic Systems with Applications to Overhead Crane Manufacturing

This project develops an overhead crane control system for precision transport and assembly operations. The crane system provides an excellent testbed for the development of advanced control theory for nonlinear, distributed, mechatronic systems. The crane model includes a nonlinear, distributed cable and typically an electrical drive motor. The theory can then be applied to many similar systems, such as smart structures, flexible rotors supported by magnetic bearings, and high speed material transport machinery. Overhead cranes have higher load capacity, larger workspace, simpler position monitoring, and easier obstacle avoidance than forklifts or Automatic Guided Vehicle. The poor payload position and orientation control of overhead cranes has limited their application in precision transport and assembly operations. Due to the flexible cable, the payload of an overhead crane swings during transit, making manual remote positioning difficult and damage or injury possible. In manufacturing environments, high speed response, accurate tracking, and good stability margins are desired. The lumped and distributed model controllers advanced in this research are based on Lyapunov theory. This research studies the fusion of the lumped and distributed Lyapunov techniques for the full nonlinear, distributed model. Additionally, the `low-pass filter-like` electrical dynamics tend to filter out part of the high-frequency component of the controller. While high-gain current feedback tends to partially null out this filtering effect, this research targets the design of backstepping-type controllers which exactly compensate for the effects of the electrical dynamics. The specific research objectives are to:i) develop saturation controllers for the electrically-driven, nonlinear rigid cable model; ii) investigate implementable boundary controllers for the linear distributed model; iii) accurately model the nonlinear, flexible cable system; iv) develop control theory for nonlinear, distributed, mechatronic systems; and v) implement the controllers on a small-scale experiment in the Robotics and Mechatronics Laboratory and a fullscale overhead crane (DEMAG 5 ton) in the new Engineering Innovation Building at Clemson University.