Exoskeleton Hip Actuator Torque Profile for Swing Phase Energy Recovery
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Solution Overview
Problem
Existing exoskeleton systems increase wearers' energy expenditure and oxygen consumption during locomotion, particularly when carrying loads, as they lack effective actuation and power transfer mechanisms to reduce energy expenditure during the swing phase.
Innovation Solution
The exoskeleton incorporates two hip actuators and a power unit that generate a torque profile to transfer mechanical energy to the wearer's lower limb during the swing phase, ensuring the force from the exoskeleton leg support is in the direction of the wearer's swing velocity, thereby reducing energy expenditure and oxygen consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an exoskeleton uses passive springs without actuation to support load carrying, then the load carrying ability is improved, but the wearer's energy expenditure increases
Solution Approach 1:
The exoskeleton recovers energy during the stance phase when the user's weight compresses the springs, and then reuses this stored energy during the swing phase to assist leg movement. The system serves itself by capturing and recycling its own operational energy needs rather than requiring external power input for every action.
Solution Approach 2:
The system recovers gravitational potential energy that would otherwise be lost when the user's leg swings downward during the swing phase. The springs capture this energy during the downward motion and release it during the upward swing, converting what would be wasted energy into useful mechanical assistance.
2Use of energy by moving object
If an exoskeleton adds actuation and power units to decrease energy expenditure, then the wearer's energy expenditure decreases, but the device complexity increases
Solution Approach 1:
The exoskeleton recovers energy during the stance phase when the user's weight compresses the springs, and then reuses this stored energy during the swing phase to assist leg movement. The system serves itself by capturing and recycling its own operational energy needs rather than requiring external power input for every action.
Solution Approach 2:
The patent replaces complex active actuation systems with a passive mechanical energy storage and release mechanism using springs. This substitution eliminates the need for motors, sensors, and control systems while still providing energy assistance through carefully positioned spring elements that leverage the user's own movement patterns.
3Device complexity
If an exoskeleton provides no actuation and power transfer, then the device complexity is reduced, but the ability to transfer power to the person is lost
Solution Approach 1:
The system recovers gravitational potential energy that would otherwise be lost when the user's leg swings downward during the swing phase. The springs capture this energy during the downward motion and release it during the upward swing, converting what would be wasted energy into useful mechanical assistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively decreases the wearer's energy expenditure and oxygen consumption during walking by transferring mechanical energy from the exoskeleton to the wearer, leading to reduced fatigue and improved load-carrying capabilities.
Implementation Method 1
a spring element configured to apply a force onto the wearer's lower limb during the swing phase
Data Source
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AI summary
A lower extremity exoskeleton (100), configurable to be coupled to a person, includes two leg supports (101, 102) configurable to be coupled to the person's lower limbs, an exoskeleton trunk (109) configurable to be coupled to the person's upper body, which is rotatably connectable to the thigh links (103, 104) of the leg supports (101, 102) allowing for the flexion and extension between the leg supports (101, 102) and the exoskeleton trunk (100), two hip actuators ( 145, 146) configured to create torques between the exoskeleion trunk (109) and the leg supports (101, 102), and at least one power unit (201) capable of providing power to the hip actuators (145, 146) wherein the power unit (201) is configured to cause the hip actuator (145, 146) of the leg support (101, 102) in the swing phase to create a torque profile such that force from the exoskeleton leg support (101, 102) onto the person's lower limb during at least a portion of the swing phase is in the direction of the person's lower limb swing velocity.