Design and Analysis of Flexible Arms for Minimum-Phase Endpoint Control

A new transmission mechanism for one-link flexible arms is presented. The endpoint control of a flexible arm has been known to be a non-minimum phase system due to the non-collocated sensor and actuator. The mechanism developed in this paper allows the endpoint control system to be a minimum phase system by having a special transmission line from its actuator to an appropriate point where the actuator torque is applied. The new flexible arm is analyzed in terms of pole-zero locations and design guidelines for the transmissions are derived. A simple prototype arm is designed, built and tested. It is compared with a non-minimum phase arm, and the minimum phase feature of the new arm is verified through experiments.