Using a redundant planar hip exoskeleton to reduce human-device interface forces

David Schmitthenner, Samuel H. Shoemaker, Anne Elizabeth Martin

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Robotic exoskeletons have the potential to improve gait rehabilitation. Currently, most exoskeletons use revolute joints that must be exactly aligned with the user's joints to prevent uncomfortable shear forces at the human-device interface. This paper presents an alternative design for a planar hip exoskeleton based on a planar Stewart platform. In theory, this mechanism does not require exact knowledge of the human hip joint center of rotation to prevent large shear forces. The total human-device system has four degrees of freedom if the human soft tissue is neglected, which does complicate the control of the system compared to a rotational exoskeleton. To find a mapping between the desired human hip angle and the four actuated joints, the task priority method is used. To determine how well the proposed device can guide the hip through a step, dynamic simulations were conducted and compared to the results for a rotational exoskeleton. The compliance in the human soft tissue was included in the simulations because it can play a significant role in both the motion of the system and the human-device forces. Both the ideal case of exact hip joint alignment and the more likely case of hip joint misalignment were considered. In addition, the effects of differing levels of human effort were compared. In all cases, both exoskeletons were well able to guide the human hip in the desired motion. In addition, the novel exoskeleton has significantly lower shear forces at the thigh human-device connection point.

Original languageEnglish (US)
Title of host publicationAerospace Applications; Advances in Control Design Methods; Bio Engineering Applications; Advances in Non-Linear Control; Adaptive and Intelligent Systems Control; Advances in Wind Energy Systems; Advances in Robotics; Assistive and Rehabilitation Robotics; Biomedical and Neural Systems Modeling, Diagnostics, and Control; Bio-Mechatronics and Physical Human Robot; Advanced Driver Assistance Systems and Autonomous Vehicles; Automotive Systems
PublisherAmerican Society of Mechanical Engineers
ISBN (Electronic)9780791858271
StatePublished - Jan 1 2017
EventASME 2017 Dynamic Systems and Control Conference, DSCC 2017 - Tysons, United States
Duration: Oct 11 2017Oct 13 2017


OtherASME 2017 Dynamic Systems and Control Conference, DSCC 2017
Country/TerritoryUnited States

All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Mechanical Engineering


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