Robot control for simultaneous impact tasks via Quadratic Programming-based reference spreading
This work addresses a specific challenge in robotic manipulation for enabling more reliable impact-based tasks, representing an incremental improvement over existing methods.
The paper tackles the problem of controlling robotic manipulators during simultaneous impacts at multiple contact points by extending the reference spreading framework with an interim control mode that disables velocity feedback to prevent harm from rapid velocity changes. The approach is formulated using quadratic programming and validated through numerical simulations on both rigid and flexible joint robot models.
With the aim of further enabling the exploitation of impacts in robotic manipulation, a control framework is presented that directly tackles the challenges posed by tracking control of robotic manipulators that are tasked to perform nominally simultaneous impacts associated to multiple contact points. To this end, we extend the framework of reference spreading, which uses an extended ante- and post-impact reference coherent with a rigid impact map, determined under the assumption of an inelastic simultaneous impact. In practice, the robot will not reside exactly on the reference at the impact moment; as a result a sequence of impacts at the different contact points will typically occur. Our new approach extends reference spreading in this context via the introduction of an additional interim control mode. In this mode, a torque command is still based on the ante-impact reference with the goal of reaching the target contact state, but velocity feedback is disabled as this can be potentially harmful due to rapid velocity changes. With an eye towards real implementation, the approach is formulated using a quadratic programming (QP) control framework and is validated using numerical simulations both on a rigid robot model and on a realistic robot model with flexible joints.