Joint stiction avoidance with null-space motion in real-time model predictive control for redundant collaborative robots

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Sammanfattning

Model Predictive Control (MPC) is an efficient point-to-point trajectory-generation method for robots that can be used in situations that occur under time constraints. The motion plan can be recalculated online to increase the accuracy of the trajectory when getting close to the goal position. We have implemented this strategy in a Franka Emika Panda robot, a redundant collaborative robot, by extending previous research that was performed on a 6-DOF robot. We have also used null-space motion to ensure a continuous movement of all joints during the entire trajectory execution as an approach to avoid joint stiction and allow accurate kinesthetic teaching. As is conventional for collaborative and industrial robots, the Panda robot is equipped with an internal controller, which allows to send position and velocity references directly to the robot. Therefore, null-space motion can be added directly to the MPC-generated velocity references. The observed trajectory deviation caused by discretization approximations of the Jacobian matrix when implementing null-space motion has been corrected experimentally using sensor feedback for the real-time velocity-reference recalculation and by performing a fast sampling of the null-space vector. Null-space motion has been experimentally seen to contribute to reducing the friction torque dispersion present in static joints.

Originalspråkengelska
Titel på värdpublikation2021 30th IEEE International Conference on Robot and Human Interactive Communication, RO-MAN 2021
FörlagIEEE - Institute of Electrical and Electronics Engineers Inc.
Sidor307-314
Antal sidor8
ISBN (elektroniskt)9781665404921
DOI
StatusPublished - 2021 aug. 8
Evenemang30th IEEE International Conference on Robot and Human Interactive Communication, RO-MAN 2021 - Virtual, Vancouver, Kanada
Varaktighet: 2021 aug. 82021 aug. 12

Publikationsserier

NamnIEEE International Conference on Robot and Human Interactive Communication, RO-MAN
ISSN (tryckt)1944-9445
ISSN (elektroniskt)1944-9437

Konferens

Konferens30th IEEE International Conference on Robot and Human Interactive Communication, RO-MAN 2021
Land/TerritoriumKanada
OrtVirtual, Vancouver
Period2021/08/082021/08/12

Ämnesklassifikation (UKÄ)

  • Robotteknik och automation

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