In this paper, a new approach is proposed to optimally plan the motion along a parametrized path for flexible joint robots, i.e., robots whose structure is purposefully provided with compliant elements. State-of-the-art methods efficiently solve the problem in case of torque-controlled rigid robots via a translation of the optimal control problem into a convex optimization problem. Recently, we showed that, for jerk-controlled rigid robots, the problem could be recast into a non-convex optimization problem. The non-convexity is given by bilinear constraints that can be efficiently handled through McCormick relaxations and spatial Branch-and-Bound techniques. In this paper, we show that, even in case of robots with flexible joints, the time-optimal trajectory planning problem can be recast into a non-convex problem in which the non-convexity is still given by bilinear constraints. We performed experimental tests on a planar 2R elastic manipulator to validate the benefits of the proposed approach. The scalability of the method for robots with multiple degrees of freedom is also discussed.
2020, IEEE ROBOTICS AND AUTOMATION LETTERS, Pages 938-945 (volume: 5)
Time-Optimal Trajectory Planning for Flexible Joint Robots (01a Articolo in rivista)
Palleschi Alessandro, Mengacci Riccardo, Angelini Franco, Caporale Danilo, Pallottino Lucia, De Luca Alessandro, Garabini Manolo
Gruppo di ricerca: Robotics