Lower Body Exoskeleton Linear Actuator Gait Control
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Solution Overview
Problem
Traditional lower body exoskeletons are cumbersome and complex due to multiple motors and links, and they fail to replicate natural walking gait as they apply forces at a single point on the foot, disrupting the user's biomechanics and requiring excessive muscle effort.
Innovation Solution
The exoskeleton design features a single linear actuator extending from the user's center of mass to the ground, with a lower end constrained near the foot using guide tubes or rocker-bar connectors, allowing for forces to be applied throughout the gait cycle without disrupting natural ankle and knee movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple motors and links are used at hip, knee, and ankle joints, then fine control over individual joints is achieved, but device complexity and weight increase significantly
Solution Approach 1:
The patent merges multiple motors and control systems into a single linear actuator that provides force along the leg's longitudinal axis. This consolidation reduces the number of components while maintaining the ability to control joint movements through a single force application point, thereby reducing device complexity while preserving operational control.
Solution Approach 2:
The single linear actuator serves multiple functions by providing force that simultaneously affects hip, knee, and ankle joints. Instead of dedicated motors for each joint, the universal actuator applies force that influences the entire lower limb kinematics, reducing overall system complexity while maintaining control capabilities.
2Device complexity
If forces are applied at a single point on the foot, then the exoskeleton structure is simplified, but natural walking gait is disrupted and muscle effort increases
Solution Approach 1:
The patent transitions from applying force at a single point on the foot to applying force along the longitudinal dimension of the leg through a linear actuator. This dimensional change allows the force to be distributed along the leg's length, influencing multiple joints simultaneously and more naturally replicating biological muscle force patterns while maintaining structural simplicity.
3Ease of operation
If individual motors are placed at each joint, then precise joint control is achieved, but weight and device complexity increase
Solution Approach 1:
The patent combines multiple heavy motor units into a single lightweight linear actuator. By merging the functions of hip, knee, and ankle motors into one actuator that applies force along the leg's longitudinal axis, the overall weight is significantly reduced while maintaining the ability to control joint movements through coordinated force application.
Data Source
AI summary
Embodiments of lower body exoskeletons having linear actuators are described. In one example, an exoskeleton includes an upper juncture assembly for positioning at least partly around a waist of a user. The exoskeleton further includes a linear actuator having a first end and a second end opposite the first end. The first end of the linear actuator is coupled to the upper juncture assembly. The exoskeleton further includes a lower juncture assembly coupled to the second end of the linear actuator. The lower juncture assembly is configured for positioning the second end of the linear actuator at a side of a foot of the user. The exoskeleton further includes a foot attachment interface for positioning at least partly around the foot of the user.