On-Line Frequency Domain Information for Control of a Flexible-Link Robot with Varying Payload

This note presents experimental results for endpoint position control of a single-link, very flexible robot arm carrying an unknown, varying payload. The control objective is to maintain endpoint position accuracy in the presence of flexure effects after rapid movement due to a rigid body slew-angle commanded position. Fast, simple, and efficient frequency domain schemes are employed for on-line controller gain adjustment within an effective scheduling framework. Only endpoint acceleration measurements and motor shaft angle measurements are utilized in relatively simple control laws where the appropriate gains have been scheduled as correlated to modal frequency information corresponding to a varying, unknown payload.