Exoskeleton Actuation With Four-Bar Linkage for Gait and Seating Comfort
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Solution Overview
Problem
Existing exoskeletons face challenges in aligning human joints with robot joints due to anatomical variability, leading to discomfort, injury, and inefficient movement. The sub-optimal placement of actuators causes discomfort and bulk, interfering with the user's gait and making sitting difficult.
Innovation Solution
The actuation system incorporates a passive joint mechanism with a multi-bar linkage, allowing for adjustable longitudinal and lateral dimensions. This configuration positions actuators posteriorly and proximate the user's torso, minimizing interference with the legs and improving seating comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If actuators are located over the user's hips and aligned posterior to the femoral head, then force transmission to the human joint is achieved, but the actuators interfere with the user's gait and cause discomfort
Solution Approach 1:
The patent relocates the actuator from a position over the hip (vertical/proximal dimension) to a position on the posterior aspect of the femur (distal/vertical dimension). This dimensional relocation moves the actuator away from the interference zone with the user's gait while maintaining the ability to transmit force to the hip joint through the posterior femoral location.
Solution Approach 2:
The patent introduces a linkage mechanism as an intermediary between the actuator and the hip joint. The actuator is positioned on the posterior femur and connected to the hip joint through this linkage, which transmits the force while allowing the actuator to be positioned optimally for comfort and gait compatibility.
2Extent of automation
If actuators are positioned proximate the user's buttocks and lower back, then actuation is achieved, but sitting becomes difficult and uncomfortable
Solution Approach 1:
The patent moves the actuator from a position on the buttocks/lower back (superior/posterior dimension) to a position on the posterior aspect of the femur (inferior/posterior dimension). This vertical relocation along the femur shaft removes the actuator from the sitting interference zone while preserving actuation capability through the linkage mechanism.
3Adaptability or versatility
If a chain or series of passive DoFs is used to allow hip rotation, then the human flexion-extension axis aligns with the actuation system, but the operation becomes complex and limited in direction
Solution Approach 1:
The patent extracts the actuator from the complex chain of passive degrees of freedom and positions it independently on the posterior aspect of the femur. This separation allows the actuator to operate more simply while still achieving the necessary joint alignment through the linkage mechanism, reducing the overall complexity of the passive DoF chain.
Data Source
AI summary
An exoskeleton includes a frame; and an actuation system. The actuation system includes a transmission device; a passive joint mechanism connecting the frame to the transmission device, the passive joint mechanism having a four-bar linkage; and a drive system couples the passive joint mechanism to the transmission device, and is arranged to drive the transmission device.