Robust and energy efficient trajectories for robots in a common workspace setting
Nina Sundström, Oskar Wigström, Bengt Lennartson · IISE Transactions · 2018
A method, incorporating robustness into trajectory planning, is proposed in this article. In the presence of delays, the suggested approach guarantees collision-free scenarios for robots with predefined paths and overlapping workspaces. Traditionally, only the time at which a robot can enter a common workspace is constrained so as to avoid collisions. If the shared zone becomes available later than planned, collisions can potentially occur if the robot is unable to stop before entering the shared space. In this work, a clearance point is introduced where the occupancy of the common workspace is evaluated. The velocity is constrained at this point such that, if necessary, the robot is able to stop at the boundary of the shared space. The closer to the boundary the evaluation is performed, the more restricted is the velocity. The problem formulation is stated in space assuming a predefined path, where robot dynamics and robust constraints are included. Multiple objectives corresponding to final time and energy consumption are considered. The impact on the system performance concerning the position and timing related to the clearance point is analyzed. An example is presented, where the optimal clearance point position is determined, based on the time at which the shared space is assumed to become available.