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

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

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    6 Citations (Scopus)


    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.
    Original languageEnglish
    Pages (from-to)180–192
    Number of pages13
    JournalInternational Journal of Intelligent Robotics and Applications
    Issue number2
    Publication statusPublished - Jun 2018


    • trajectory planning
    • exoskeleton
    • sit-to-stand
    • assistive devices
    • Exoskeleton
    • Trajectory planning
    • Sit-to-stand
    • Assistive devices


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