Online Trajectory Generation: Reactive Control With Return Inside an Admissible Kinematic Domain

Abstract

As humans and robots work more and more closely, robots must quickly react to unforeseen human behavior. Online Trajectory Generation (OTG), based on simple trajectory models like series of polynomial cubic functions, has demonstrated its efficiency to plan and control reactive motions of robots. However to ensure the safety and comfort of humans, fast trajectory adaptation algorithms are necessary to bring back the robot inside an acceptable domain that is defined by a set of kinematic constraints. The algorithm presented herein extends a time-optimal OTG to cope with non admissible robot's state. This feature enables time-variant kinematic constraints. With the possibility to specify velocity and acceleration at both ends under short computation times, it makes the robot able to react quickly to unforeseen events. Short computation times can lead to more refined architectures where sensors can be integrated to a low control level and make the system more reactive.