Parallel Four-Bar Exoskeleton Architecture for Ball-and-Socket Joints
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Solution Overview
Problem
Conventional exoskeleton robotic devices with serial chain architectures are inefficient for ball and socket joints like the shoulder, hip, wrist, and ankle, as they require larger motors to amplify torques and consume more energy due to the moment arm associated with multiple linkages, which is not anatomically similar to human joints.
Innovation Solution
A parallel actuated exoskeleton architecture using a base and platform connected by multiple substructures, where these substructures are actuated in parallel to move the platform within a spherical workspace, reducing mechanical interference and energy consumption by utilizing a four-bar spherical parallel manipulator with three actuated substructures and cooperative control techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If serial chain architecture with multiple linkages is used to augment ball and socket joint motion, then the joint motion can be achieved, but the moment arm amplifies torques requiring larger motors and consuming more energy
Solution Approach 1:
The exoskeleton divides the augmentation function into multiple independent substructures (at least three) that work in parallel, each contributing to the overall motion without requiring large moment arms. This segmentation allows the system to achieve complex ball and socket joint motion while maintaining smaller, more energy-efficient actuators.
Solution Approach 2:
The patent merges multiple actuation paths into a unified parallel architecture where multiple substructures cooperate to move the platform. This combining of parallel actuation paths eliminates the need for large moment arms while maintaining full motion capability, directly reducing energy consumption compared to serial chain approaches.
2Adaptability or versatility
If serial chain architecture with multiple linkages is used to augment ball and socket joint motion, then the joint motion can be achieved, but larger motors are required which increase device complexity
Solution Approach 1:
The system segments the actuation function across multiple smaller substructures rather than relying on a few large motors. Each substructure uses smaller motors that work in parallel, reducing individual motor size and overall device complexity while maintaining full motion capability.
Solution Approach 2:
Multiple smaller motorized substructures are merged into a unified parallel system that collectively provides the required motion. This merging allows the use of smaller, less complex motors compared to the large motors required in serial chain architectures.
3Ease of manufacture
If serial chain architecture is used, then simple one degree-of-freedom joints can be actuated, but ball and socket joints cannot be shared anatomically similar manner
Solution Approach 1:
The complex ball and socket joint actuation is segmented into multiple independent substructures, each handling a portion of the motion. This segmentation allows the system to achieve complex multi-degree-of-freedom motion while keeping each individual substructure relatively simple and easier to manufacture.
Solution Approach 2:
The patent transitions from one-dimensional serial chain actuation to multi-dimensional parallel actuation. By arranging substructures in parallel around the joint, the system can accommodate the multi-axis motion of ball and socket joints in an anatomically similar manner, improving adaptability while maintaining manufacturing feasibility.
4Use of energy by moving object
If parallel actuated architecture is used, then torque and energy consumption are reduced, but the system complexity increases
Solution Approach 1:
The system segments the actuation into modular substructures that can be independently designed and controlled. This segmentation reduces energy consumption through parallel actuation while managing complexity through modularity, making the system more maintainable and controllable despite the increased number of components.
Data Source
AI summary
An exoskeleton for interfacing with a joint includes a base configured to be coupled to a user, a platform configured to be coupled to the user proximate the joint, and a plurality of substructures extending between the base and the platform. The substructures are actuated in parallel in order to move the platform.