Momentum-based trajectory planning for lower-limb exoskeletons supporting sit-to-stand transitions

Gaurav Patil, Lillian Rigoli, Michael Richardson, Manish Kumar, Tamara Lorenz

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The ability to move one’s body from sitting to standing is a crucial ability for independent living. Especially for seniors with decreasing muscular strength, sit-to-stand (STS) transitions are exceptionally risky and often call for assistance. In general, an STS transition is a complex full-body activity that requires the synergistic coordination of the upper and lower limbs and trunk. An exoskeleton can support this multiple degrees-of-freedom problem by controlling the trajectory of the center of mass of the resulting human–robot system. However, while human movement is highly variable, exoskeletons usually only support one of multiple possible solutions. In this paper, we first present an analysis of factors that affect human center of mass trajectory and show that different human movement velocity profiles during STS transitions require different control strategies of the center of mass. Therefore, we propose a model based on horizontal and vertical momentums that enables efficient planning of the center of mass trajectory for any STS transition velocity. Finally, we validate this model by presenting an inverse kinematics solution for the CoM to joint angle problem using a deep Long Short-Term Memory (LSTM) network.
LanguageEnglish
Pages180–192
Number of pages13
JournalInternational Journal of Intelligent Robotics and Applications
Volume2
Issue number2
DOIs
Publication statusPublished - Jun 2018

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Momentum
Trajectories
Planning
Inverse kinematics
Robots

Keywords

  • trajectory planning
  • exoskeleton
  • sit-to-stand
  • assistive devices

Cite this

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title = "Momentum-based trajectory planning for lower-limb exoskeletons supporting sit-to-stand transitions",
abstract = "The ability to move one’s body from sitting to standing is a crucial ability for independent living. Especially for seniors with decreasing muscular strength, sit-to-stand (STS) transitions are exceptionally risky and often call for assistance. In general, an STS transition is a complex full-body activity that requires the synergistic coordination of the upper and lower limbs and trunk. An exoskeleton can support this multiple degrees-of-freedom problem by controlling the trajectory of the center of mass of the resulting human–robot system. However, while human movement is highly variable, exoskeletons usually only support one of multiple possible solutions. In this paper, we first present an analysis of factors that affect human center of mass trajectory and show that different human movement velocity profiles during STS transitions require different control strategies of the center of mass. Therefore, we propose a model based on horizontal and vertical momentums that enables efficient planning of the center of mass trajectory for any STS transition velocity. Finally, we validate this model by presenting an inverse kinematics solution for the CoM to joint angle problem using a deep Long Short-Term Memory (LSTM) network.",
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Momentum-based trajectory planning for lower-limb exoskeletons supporting sit-to-stand transitions. / Patil, Gaurav; Rigoli, Lillian; Richardson, Michael; Kumar, Manish; Lorenz, Tamara.

In: International Journal of Intelligent Robotics and Applications, Vol. 2, No. 2, 06.2018, p. 180–192.

Research output: Contribution to journalArticleResearchpeer-review

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