Continuous Steering-Function Control of Robot Carts.

Paths planned for routing an automatically guided vehicle (AGV) around factories or offices generally comprise a concatination of line and circular arc segments. For most AGVs, the steering functions required to keep the position and heading of the cart continuously aligned with such paths will have discontinuities at the line-arc-line transition points, since the curvature of the path is discontinuous at these points. Since carts have inertia and limited steering forces, tracking errors are the inevitable result. Three alternative approaches for eliminating steering discontinuities are: 1) change the steering mechanism; 2) change the guide-point on the cart; 3) change the curves on the path.