Faster Detection of Step Initiation for the Lower Limb Exoskeleton with Vertical GRF Events

Abstract

-We propose a new approach called as a peak time approach for faster detection of step initiation for the lower limb exoskeleton. As faster detection of step initiation is an important criterion in evaluating the lower limb exoskeleton, many studies have investigated approaches to detect step initiation faster, including using electromyography, the center of pressure, the heel-off time and the toe-off time. In this study, we will utilize vertical ground reaction force events to detect step initiation, and compare our approach with prior approaches. Additionally, we will predict the first step's heel strike time with vertical ground reaction force events from multiple regression equations to support our approach. The lower limb exoskeleton should assist the operator's movement much faster and more reliably with our approach.

Design and Evaluation of the Unmanned Technology Research Center Exoskeleton Implementing the Precedence Walking Assistance Mechanism

“…10 show joint ROMs of the UTRCEXO for hip and knee. Joint ROMs of the UTRCEXO were similar to the human gait pattern analyzed in the previous study [25]. In that previous study, the joint ROMs were 0 to 60 degrees for the knee flexion and extension and 5 to 40 degrees for the hip flexion and extension.…”

“…The peak time approach detects step initiation of the operator with two particular ground reaction force events before visible movements occur, such as heel-off, knee flexion, and toe-off movement [25]. Once the UTRCEXO detects step initiation, the human intention detector of the UTRCEXO transmits each required joint torque as a reference torque to the motion controller using a RS485 communication line.…”

“…We previously analyzed human gait patterns from step initiation to continuous walking, and proposed a new approach called the peak time approach to detect step initiation [25]. For the UTRCEXO, we defined the states from step initiation to step termination with the acquired data from FSRs and F/T sensors.…”

Precedence walking assistance mechanism for exoskeletons with improved detection of step initiation based on gait analysis

“…We observed two vertical GRF events for step initiation [16], which occurred prior to any visible movements. First, a vertical GRF intersection between the left and right foot (○).…”