Docking to pallets with feedback from a sheet-of-light range camera

Abstract

The problem studied is feedback for docking a mobile robot or AGV, to a pallet. The pallet is of known size but with an essentially unknown load. The pallet has an initial uncertainty in pose (position and orientation) of the order /spl plusmn/15 cm and /spl plusmn/20 degrees. The docking error is required to be within /spl plusmn/1 cm and /spl plusmn/1 degree with "very low" failure rate. For the docking a combination of a range camera and a video camera is used. In the paper the range camera is emphasized. Experimental results from this work in progress are presented. Successful docking has been made with typical /spl plusmn/5 mm as errors. Currently one weak part is the integration with the control system on board the robot. Our persistent experience from this and earlier tests is that the weak part when using non-contact sensing for feedback in robots is the association problem. It should be mentioned that the resolution of a range camera is strongly distance dependent. One finding in the paper is that this type of docking is feasible and can be made self-monitoring.