On the dynamic performance of parallel kinematic manipulators with actuation and kinematic redundancies

• A methodology to model planar PKMs with several levels of actuation and/or kinematic redundancies is described.
• The evaluation of the torque requirements to perform pre-defined trajectories with redundant PKMs is carried out.
• Different strategies to tackle kinematic redundancies are exploited.
• The dynamic performance of the redundant manipulator is highly dependent on the pre-defined trajectory.
• A Dynamic Index to evaluate the dynamic performance of redundant PKMs has been proposed and evaluated in the workspace.Dynamic Maps enable fair comparisons between the dynamic performances of different planar redundant PKMs.

The performance of parallel kinematic manipulators may be enhanced by the use of actuation and kinematic redundancies since they promote a significant reduction in the singularities and homogenization on the actuation forces. Considering these facts, this manuscript proposes a strategy to assess if the use of one or more actuation/kinematic redundancies can be good alternatives to improve the dynamic performance of a planar parallel kinematic manipulator. This may not be a trivial task since their dynamic performance can be highly dependent on which trajectory is performed and how the redundancy is treated. To overcome the former issue, a dynamic index depicted in the system workspace is proposed. To overcome the latter issue, different optimization strategies to treat actuation and kinematic redundancies are compared. From numerical results, one can conclude that the dynamic performance of the manipulator can only be enhanced if the redundancies are treated accordingly. Moreover, the benefits of redundancy are highly dependent on the chosen trajectory, the end effector's position and orientation.

Graphical AbstractFigure optionsDownload as PowerPoint slide