380 Trajectory Generation for Sensor - Driven and Time - Varying Tasks

In on-line robot trajectory generation, a connecting polynomial is normally used to remove discontinuities in velocity and acceleration between adjacent path segments. This article presents a new technique for performing such transitions in which adjacent path segments are "blended" together, with excess acceleration being removed using an estimate of the initial path velocities. Because this method requires no advance knowledge of the path segments, it can handle situations where the paths are changing with time (as when tracking sensor or control inputs). The method can also be used to adjust the spatial shape of the transition curve (such as to have it pass around or through the "via point"), which may be necessary to handle constraints imposed by different types of manipulator tasks. When the blended paths are nonlinear, it is possible to set a tight bound on the resulting transition acceleration. The blend technique works directly for vector trajectories and can be modified to handle 3-D rotational trajectories. A simple trajectory generation algorithm is presented as an illustration.