Ph.D. Proposal Presentation by John R. Huey
Wednesday, April 27, 2005

(Dr. William Singhose, Chair)

"The Intelligent Combination of Input Shaping and PID Feedback Control"


Input shaping and Proportional-Integral-Derivative (PID) feedback control are simple, easy-to-implement and generally low cost control strategies. Considering this, it is remarkable that they are also very effective control techniques. In fact, a majority of the world's feedback controllers utilize PID (or the subset PD) control. In addition, input shaping has seen significant use on real-world machines such as cranes, micro-mills, coordinate measuring machines, computer disc drive manufacturing machines, spacecraft, etc.

However, despite similarities in effectiveness and ease of implementation, input shaping and PID feedback control are fundamentally different strategies. Input shaping is an anticipatory control scheme capable of enabling quick, low-vibration motions. PID feedback control is reactive in nature, and it is primarily required to deal with problems such as modelling errors, disturbances and non-linearities. Of course, PID control is also used to reduce vibrations (as in the case of input shaping). But, because it is a reactive controller, it is usually slower than input shaping.

Because of their effectiveness and practicality, as well as the fact that they address important and complimentary control issues, it would be advantageous to combine these two control strategies. The result would still be practical and effective, yet would now address a range of system phenomenon beyond that which is capable by either of the individual control techniques. However, there is a definite gap in the state-of-the-art technology. For example, little research has addressed the intelligent combination of traditional, outside-the-loop input shaping and PID feedback control. In addition, only a few researchers have attempted to place input shaping filters within feedback loops.

This research seeks to study the intelligent combination of input shaping and PID feedback control by developing a concurrent design procedure for outside-the-loop input shaping/PID feedback combinations and by analyzing the effect of placing input shaping filters within feedback loops. In addition, this project will aid in the construction and programming of a new experimental testbed a miniature tower crane.