Elastic Actuator Torque Sensing Without Separate Force Sensors
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Solution Overview
Problem
Existing actuators for motion assistance devices, such as those used in robots and industrial facilities, face challenges in efficiently transmitting power while accommodating varying user forces and maintaining durability, often requiring separate force/torque sensors and amplifiers, which increase size and complexity.
Innovation Solution
The proposed actuator design incorporates a motor, a series of power transmitters performing coaxial rotation, an elastic element connecting adjacent transmitters, and a controller determining torque based on measured rotation angles and elasticity coefficients, allowing power transmission and force absorption without separate sensors, thus reducing size and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate force/torque sensors and amplifiers are used to measure interaction forces, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the force measurement function with the existing angle sensors by utilizing the elastic deformation of the elastic element connecting power transmitters. The controller calculates interaction forces by computing the difference between rotation angles measured by angle sensors mounted on different power transmitters, thereby merging force measurement capability into the existing motion sensing system without adding separate force/torque sensors or amplifiers.
2Measurement precision
If separate force/torque sensors and amplifiers are added, then measurement precision is improved, but the actuator size increases
Solution Approach 1:
The patent merges the force measurement functionality into the existing actuator structure by utilizing angle sensors already present for motion control. The elastic element's deformation, which reflects interaction forces, is measured indirectly through rotation angle differences detected by existing angle sensors, eliminating the need for additional force sensors and amplifiers that would increase actuator volume.
3Power
If rigid connections are used between power transmitters, then power transmission efficiency is improved, but durability decreases when accommodating varying user forces
Solution Approach 1:
The patent changes the mechanical connection parameter from rigid to elastic by introducing an elastic element between adjacent power transmitters. This elastic connection allows the system to accommodate varying user forces and external shocks while maintaining effective power transmission, thereby improving durability without significantly compromising transmission efficiency.
Solution Approach 2:
The elastic element serves as a pre-configured cushioning mechanism between power transmitters, absorbing unexpected external forces and shocks before they can cause damage to the actuator components. This beforehand cushioning protects the rigid mechanical components while allowing normal power transmission during regular operation.
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
This design enables efficient power transmission and force absorption, improving the actuator's durability and reducing size by measuring interaction forces through rotation angle differences, eliminating the need for additional sensors and amplifiers.
Implementation Method 1
an elastic element configured to connect the first power transmitter and the second power transmitter
Data Source
AI summary
An actuator includes a plurality of power transmitters configured to transmit power sequentially, and an elastic element configured to connect a first power transmitter and a second power transmitter that are adjacent to each other and perform a coaxial rotation motion, among the plurality of power transmitters.