Exoskeleton Actuator with Elastic Return Element for Energy Assistance
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Solution Overview
Problem
Exoskeletons that provide force assistance tend to consume excessive electrical energy, particularly in lower body actuators like hip or knee joints, due to the need to support user and structure weight, especially during high-amplitude movements.
Innovation Solution
An exoskeleton structure incorporating a combination of active and passive assistance mechanisms, where an actuator provides active assistance in one angular range of movement and a pre-loaded elastic return element offers passive assistance in another, reducing power consumption by limiting actuator power delivery during specific movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If actuators are disposed in the lower portions of the exoskeleton to assist hip or knee movements, then the user receives effective force assistance during movements, but the electrical energy consumption increases significantly
Solution Approach 1:
The patent combines active assistance (electrical actuator) and passive assistance (elastic return element) into a hybrid system. The elastic element stores and releases energy to supplement the actuator's work, particularly during high-amplitude movements, thereby reducing the energy burden on the electrical actuator while maintaining effective force assistance.
Solution Approach 2:
The system dynamically switches between active and passive assistance modes based on the movement phase. The elastic return element is engaged during high-amplitude movements (such as standing up or sitting down) where passive energy storage and release is most beneficial, while the actuator provides continuous active assistance during normal walking phases, optimizing energy consumption across different operational conditions.
2Stability of the object's composition
If actuators support all weights above them (user weight + structure weight), then the exoskeleton provides stable support, but the power consumption increases especially during large-amplitude movements
Solution Approach 1:
The elastic return element is pre-loaded during the deceleration phase of movement (when the user is lowering themselves or extending the leg), storing potential energy in advance. This pre-stored energy is then released during the subsequent movement phase, reducing the power demand on the actuator during high-amplitude movements while maintaining stable support throughout the motion.
3Force
If the actuator delivers full power during all movement phases, then effective assistance is provided during complete flexure, but electrical energy consumption is excessive during walking and running phases
Solution Approach 1:
The system applies partial active assistance from the actuator during phases where passive assistance suffices (normal walking and running), while engaging full active assistance only when necessary (during complete flexure or when additional force is required). The elastic return element provides supplemental assistance during high-amplitude movements, allowing the actuator to operate at reduced power levels during routine phases while maintaining effective assistance when needed.
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 allows for effective user movement assistance while minimizing electrical energy consumption, particularly during walking and running phases, and provides adequate support during full flexure of the hip or knee without excessive energy use.
Implementation Method 1
an elastic return element arranged to: in a first angular range of movement of the rotor with respect to the stator, not exert any return force on the rotor and, in a second angular range of movement of the rotor with respect to the stator, exert a return force tending to oppose a rotation of the rotor with respect to the stator in a first direction of rotation, and to assist rotation of the rotor with respect to the stator in a second direction of rotation, opposite to the first direction of rotation
Data Source
AI summary
The invention relates to an exoskeleton structure that provides force assistance to a user, comprising:a first module capable of being attached to a first portion of the body of a user,a second module capable of being attached to a second portion of the body of the user, the second module being connected to the first module by means of a joint (52, 62) allowing rotation of the second module (5, 6) with respect to the first module,an actuator (521) comprising a stator (522) and a rotor (523) capable of being driven in rotation with respect to the stator (522) to move the second module (5, 6) in rotation with respect to the first module (1, 5), andan elastic return element (524) arranged to: in a first angular range of movement (α1) of the rotor with respect to the stator (522), not exert any return force on the rotor (523) and, in a second angular range of movement (α2) of the rotor (523) with respect to the stator (522), exert a return force tending to oppose rotation of the rotor (523) with respect to the stator (522) in a first direction of rotation (A) and to assist rotation of the rotor with respect to the stator in a second direction of rotation (B) opposite to the first direction of rotation.