Segmented Hoop Actuator for Exoskeleton Torque and Wearability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional central-shaft electric motors used in electromechanical exoskeletons face challenges in achieving high torque density while maintaining a balanced weight distribution, often requiring larger and heavier motors that are unevenly distributed around the body.
Innovation Solution
A wearable motion assistive device featuring a shaftless motor with a stator and rotor that circumscribe the body, allowing for a closed or open condition to facilitate installation and removal, and utilizing a bearing assembly with multiple small bearings to maintain a consistent gap between the stator and rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional central-shaft electric motors are used to increase available torque, then torque output is improved, but device weight and size increase, negatively affecting torque density
Solution Approach 1:
The motor is divided into two separate segments (stator and rotor) that can be worn independently around the body. The stator is mounted on a frame while the rotor is mounted on the appendage support, allowing the motor to be split across different locations rather than concentrated in one heavy unit. This segmentation enables torque generation while distributing weight to maintain balance and improve torque density.
2Force
If traditional central-shaft electric motors are used to increase available torque, then torque output is improved, but weight distribution becomes excessively uneven
Solution Approach 1:
By splitting the motor into stator and rotor segments worn at different locations (frame and appendage support respectively), the weight is distributed more evenly around the body. This prevents excessive concentration of mass at one location and maintains better overall balance and stability during movement.
Solution Approach 2:
The motor configuration transitions from a centralized single-point mounting to a distributed arrangement across multiple dimensions of the body (frame and appendage). This spatial redistribution of motor components achieves better weight balance while maintaining the required torque output capability.
3Weight of moving object
If a shaftless motor with circumscribing stator and rotor is used, then torque density and weight distribution are improved, but installation and removal become challenging
Solution Approach 1:
The motor is segmented into two wearable components (stator and rotor) that can be independently installed and removed. The stator attaches to the frame while the rotor attaches to the appendage support, allowing flexible installation without requiring passage through a central opening. This segmentation resolves the installation difficulty while maintaining the torque density benefits of the shaftless design.
4Reliability
If a bearing assembly with multiple small bearings is used to maintain gap between stator and rotor, then motor performance is improved, but device complexity increases
Solution Approach 1:
The bearing assembly uses multiple small bearings distributed around the motor perimeter instead of a single large bearing. This segmentation of the bearing function into multiple smaller components maintains the critical air gap between stator and rotor while allowing for more compact and manageable construction, potentially reducing overall complexity despite the increased number of small parts.
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
The solution provides a high torque density with a balanced weight distribution, enabling efficient movement assistance while allowing for easy installation and removal of the device around the body.
Implementation Method 1
The bearing assembly may include a plurality of bearings circumferentially spaced and mounted on a carrier. Each bearing of the plurality of bearings may have a rotational axis that forms an obtuse angle with a rotational axis of the actuator.
Data Source
AI summary
A wearable motion assistive device such as an electromechanical exoskeleton includes an actuator that circumscribes a natural or artificial portion of the body of a user when the user wears the device. The actuator includes an interior stator, an exterior rotor, and a bearing assembly, each of which may be segmented to permit the actuator to be installed around or be removed from around the portion of the user's where the device is worn. The bearing assembly includes a plurality of small roller bearings mounted on a carrier affixed to the stator and is segmented along the carrier between roller bearings.