Lower Extremity Enhancer Actuator Torque Control
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Solution Overview
Problem
Existing robotic exoskeletons for lower extremities are limited in their ability to enable users to carry loads without assistance, often requiring users to hold onto walking aids and relying on muscle activity or conscious commands, and lack the flexibility to mimic the full range of human lower extremity movements.
Innovation Solution
A lower extremity enhancer with multiple jointed links and powered by actuators, allowing for seven degrees of freedom of movement, enabling users to carry loads without manual control by tracking the user's leg motions and providing assistance through hydraulic or other actuators, while being adjustable and safe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If robotic exoskeletons rely on muscle activity interpretation or conscious commands to control joint motion, then the system can be operated with simple control mechanisms, but the user must hold onto walking aids and the system lacks flexibility to mimic full human lower extremity movements
Solution Approach 1:
The system uses sensors to automatically detect user gait phase and leg movement, eliminating the need for manual control inputs. The controller autonomously determines when to apply torque based on detected movement, allowing the exoskeleton to serve itself by sensing and responding to user needs without requiring the user to actively control it
Solution Approach 2:
The system incorporates sensors that continuously monitor user leg movement and provide feedback to the controller. This feedback loop enables the system to detect gait phase and movement characteristics, automatically adjusting assistance timing and magnitude to match natural human gait patterns without requiring manual intervention
2Productivity
If the exoskeleton system provides powered assistance through actuators, then users can carry loads without manual control, but the system complexity increases with multiple actuators and control mechanisms
Solution Approach 1:
The system divides the leg into multiple segments (thigh and shank) with separate actuators for each segment. This segmentation allows independent control of hip and knee joints, enabling natural gait assistance while managing complexity through modular actuator design that can be controlled by a centralized gait-phase detector
Solution Approach 2:
The sensor system serves multiple functions: detecting gait phase, determining movement characteristics, and providing timing information for actuator activation. This multi-functionality reduces overall system complexity by using a single sensing infrastructure for multiple control decisions rather than requiring separate sensing systems for each function
3Adaptability or versatility
If the exoskeleton is designed to mimic full human lower extremity movements with seven degrees of freedom, then the system provides natural and safe movement, but the device weight and structural complexity increase
Solution Approach 1:
The system implements dynamic control where actuator torque is applied only during specific gait phases when assistance is needed, rather than continuously constraining movement. The spring elements provide passive dynamic assistance that automatically adapts to user movement, reducing the need for heavy active actuators while maintaining full range of motion capability
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
Enables users to walk, run, and perform various movements while carrying loads with minimal impedance, allowing a full range of motion and safety features to prevent injury, without the need for manual control or assistance.
Implementation Method 1
The legs supports are powered by a plurality of actuators adapted to apply torques to the leg supports in response to movement of the user's legs
Data Source
AI summary
A lower extremity enhancer to be worn by a user to enable the user to carry a load includes two leg supports having a plurality of jointed links. Proximal ends of the leg supports are connected to a back frame adapted to carry the load. Distal ends of the leg supports are connected to two foot links. The leg supports are powered by a plurality of actuators adapted to apply torques to the leg supports in response to movement of the user's legs.