TIP POSITION CONTROL OF A FLEXIBLE ONE-ARM ROBOT WITH PREDICTIVE ADAPTIVE OUTPUT-FEEDBACK IMPLEMENTED WITH LATTICE FILTER PARAMETER IDENTIFIER

Precision high bandwidth tip position control of a flexible arm with non-colocated sensors and actuators is a control problem to be solved for the advancement of the state-of-the-art in space and next generation industrial robots. A lattice filter structure is used for real-time parameter estimation of a flexible one-arm robot. The estimated parameters are employed in the control calculations based on predictive adaptive output feedback control. The lattice filters are particularly suitable for identifying the parameters of mechanical systems with distributed flexibility, since the order of the filter may be adjusted on-line as the task conditions require. Hence, the required dynamic model order for an accurate control does not have to be decided upon beforehand. Lattice filters have the potential to adjust their orders in real-time to find the appropriate model order for accurate control under the current task conditions. A predictive adaptive control is studied using tip position measurements. Although there are potential instability problems due to the non-minimum phase nature of the open loop system as a result of sensor-actuator non-colocation, the discrete-time predictive adaptive control implemented with the lattice filter (forming a special self-tuning regulator) showed good success in precision, high-bandwidth tip position control of a flexible one-arm robot. © 1990.