Orthosis Actuator with Nested Motor and Gear System
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Solution Overview
Problem
Current lower-limb rehabilitation orthoses are often stationary, costly, and large, limiting their availability and effectiveness for patients who need to relearn walking after a stroke, as they lack backdrivability and high torque density in a compact, portable form.
Innovation Solution
A novel powered limb orthosis design integrating motor encapsulation technology, a single-stage gearbox, forced air cooling system, and heat sink to achieve high output torque with low-ratio transmission and backdrivability, ensuring mechanical transparency and comfort for users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high-ratio transmission is used to increase output torque, then torque density is improved, but mechanical impedance increases and backdrivability is lost
Solution Approach 1:
The patent replaces traditional high-ratio mechanical transmissions with a motor encapsulation system that integrates the motor directly with the transmission mechanism. This substitution allows for low-ratio transmission while maintaining high output torque through direct motor coupling, eliminating the mechanical impedance and preserving backdrivability for users with residual control.
Solution Approach 2:
The patent merges the motor and transmission into a single integrated actuator unit. By combining these previously separate components, the system achieves compact packaging with low-ratio transmission, eliminating the need for complex high-ratio gear trains while maintaining high torque output and enabling backdrivability.
2Volume of moving object
If motor and transmission are integrated into single package, then device portability is improved, but thermal management becomes more challenging
Solution Approach 1:
The patent nests the transmission components within the motor housing, creating a compact integrated actuator. The transmission is positioned inside the motor's inner diameter, allowing the entire motor-transmission assembly to fit within a single package while maintaining effective thermal pathways for heat dissipation.
Solution Approach 2:
The patent introduces a forced air cooling system as an intermediary thermal management mechanism. This cooling system acts as a mediator between the integrated motor-transmission heat sources and the external environment, effectively removing heat from the compact package without increasing its volume.
3Ease of operation
If low-ratio transmission is used with integrated motor, then backdrivability is improved, but output torque density decreases
Solution Approach 1:
The patent changes the motor's operational parameters through encapsulation, allowing it to operate at optimized current and speed ranges that compensate for the low-ratio transmission. This parameter optimization enables the motor to generate sufficient torque density directly, eliminating the need for high-ratio mechanical multiplication while preserving backdrivability.
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 compact, self-contained orthosis with high torque density and low backdrive torque, enhancing user participation and comfort during physical therapy, suitable for both clinical and daily use, with improved thermal management and reduced manufacturing costs.
Implementation Method 1
The actuator further includes a forced air cooling system
Implementation Method 2
The actuator further includes a heat sink
Data Source
AI summary
The present disclosure includes, in one embodiment, an orthosis device. The orthosis device, in one embodiment, includes an actuator housing, an electric motor contained within the actuator housing, the electric motor including a motor stator and a motor rotor forming an inner diameter, and the electric motor further having high output torque. The orthosis device according to this embodiment further includes a transmission including a gear system contained within the actuator housing, the gear system positioned within the inner diameter of the electric motor, and a body attachment coupled to an output of the gear system.