Cable-Driven Exoskeleton with Remote Motors for Arm Rehabilitation
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Solution Overview
Problem
Existing arm training devices for stroke survivors are hindered by their weight, which complicates rehabilitation due to the added bulk of motors and servos, making it difficult for users with weakened musculature to effectively control and stabilize arm posture and hand function.
Innovation Solution
A cable-driven upper arm exoskeleton with remotely located motors and spools suspended above the user, utilizing adjustable cuffs and cables made of metal or nylon, along with a processor-controlled system to vary cable lengths and provide assistance through a range of forces, facilitating arm movement and rehabilitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If motors and servos are mounted to the shoulder cuff to drive arm training, then arm movement assistance is provided, but the device weight increases significantly making it cumbersome for weakened users
Solution Approach 1:
The patent extracts the heavy motors and servos from the wearable shoulder cuff and relocates them to a stationary overhead support structure. Only the lightweight cable-driven exoskeleton components remain on the user, providing movement assistance without the burden of heavy actuators. This separation resolves the contradiction by maintaining operational assistance while eliminating excessive weight.
Solution Approach 2:
The patent introduces cables as intermediary elements that transmit force from the remotely located motors to the user's arm. The cables act as flexible mediators, allowing the heavy drive mechanism to remain stationary while still providing dynamic movement assistance to the user's limb through tension-based force transmission.
2Power
If heavy motors are mounted on the exoskeleton to provide sufficient driving force, then arm training capability is improved, but the user's ability to control and stabilize arm posture deteriorates
Solution Approach 1:
The heavy motor components are extracted from the wearable exoskeleton and placed in a stationary overhead structure. This allows the exoskeleton to provide necessary driving force through lightweight cables without adding mass that would impede the user's natural arm posture control and stabilization abilities.
Solution Approach 2:
The patent replaces direct mechanical coupling of heavy motors to the user's arm with a cable-pulley mechanical system. This substitution allows force transmission while maintaining user control, as the cables can be tensioned and released without the inertia and bulk of directly mounted motors, preserving the user's ability to modulate arm posture.
3Weight of moving object
If the exoskeleton is made lightweight for user comfort, then wearability is improved, but the driving capability for effective rehabilitation deteriorates
Solution Approach 1:
The heavy power-generating components (motors and servos) are extracted from the wearable exoskeleton and relocated to a stationary overhead support structure. The exoskeleton itself remains lightweight with only cables, pulleys, and structural elements, ensuring user comfort while the remote motors provide sufficient driving capability for effective rehabilitation through cable tension.
Data Source
AI summary
A device and method for assisting a user to articulate a limb. The device has an upper section, a lower section, and at least one joint between the upper and lower section. The device comprises an exoskeleton with a first cuff coupled to the lower section of the user's limb, a second cuff coupled to the upper section of the user's limb and a third cuff coupled to a portion of the user's body above the upper section of the limb. At least one cable is attached to the first cuff and at least one cable is attached to the second cuff. A series of drivers located remotely from the exoskeleton are attached to cables and are connected to a processor. The processor transmits signals to the drivers to vary the lengths of the cables to guide articulation of the user's limb.