MR Fluid Clutch Actuator for Low Inertia Robotic Manipulation
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Solution Overview
Problem
Current robotic manipulators face challenges in ensuring safety during collisions with humans due to high reflected actuator inertia and the susceptibility of electronic components to failure, which limits their ability to effectively control and minimize impact forces, especially at high velocities.
Innovation Solution
A clutch system using Magneto-Rheological (MR) or Electro-Rheological (ER) fluids with viscosity that changes based on an electromagnetic field, allowing for adjustable torque transmission between input and output shafts, which reduces the effective inertia and enhances safety by decoupling the actuator inertia from the link inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional actuators with high power are used to control impact forces during collisions, then the ability to minimize impact forces improves, but the reflected actuator inertia increases, worsening collision safety
Solution Approach 1:
The patent applies dynamics by making the torque transmission characteristic of the actuator dynamically adjustable through MR/ER fluids. The fluid's viscosity changes in real-time based on applied electromagnetic fields, allowing the actuator to transition between high-torque/low-inertia and low-torque/high-inertia states, thereby resolving the contradiction between impact force control capability and reflected inertia
Solution Approach 2:
The patent changes the physical parameter of the transmission fluid (viscosity) in response to operational conditions. By adjusting the viscosity of MR/ER fluid through electromagnetic field application, the actuator can modify its torque transmission characteristics, enabling it to provide high torque when needed while maintaining low reflected inertia during normal operation, thus resolving the force-control versus inertia contradiction
2Force
If joint torque controlled systems with electronic components are used to attenuate impact loads, then the ability to control collisions within bandwidth improves, but reliability decreases due to susceptibility of electronic components to failure
Solution Approach 1:
The patent replaces electronic control components with a passively safe mechanical system based on MR/ER fluid characteristics. The inherent properties of the fluid provide passive safety mechanisms that do not rely on electronic sensors or controllers, thereby maintaining impact load attenuation capability while significantly improving system reliability through elimination of failure-prone electronic components
Solution Approach 2:
The MR/ER fluid-based actuator system is self-regulating and does not require external electronic control for basic safety functions. The fluid automatically adjusts its viscosity based on applied fields, providing intrinsic safety without relying on external electronic monitoring or control systems, thus improving reliability while maintaining force control
3Speed
If faster and more powerful actuators are used to control high velocity collisions, then collision control performance improves, but device complexity increases
Solution Approach 1:
The patent achieves high-speed collision control without increasing actuator complexity by changing the dynamic characteristics of the transmission fluid. The MR/ER fluid allows the same actuator to rapidly switch between different torque transmission states through electromagnetic field application, providing high-speed response capability without requiring multiple actuators or complex mechanical configurations
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 system provides a safety margin while maintaining performance by linearizing the torque transmission relationship and reducing the effective inertia of robotic links, thereby improving the manipulator's ability to safely operate in close proximity to humans.
Implementation Method 1
a torque transmission fluid whose viscosity changes based on the intensity or strength of an electromagnetic field passing through the fluid
Implementation Method 2
Devices utilizing the unique properties of Magneto-Rheological (MR) and Electro-Rheological (ER) fluids have been developed for robotic applications
Data Source
AI summary
Systems and methods relating to a clutch system for use in controllably transmitting torque from an input shaft to an output shaft. The clutch system has a torque transmission fluid that has a viscosity that changes based on the strength of an electromagnetic field passing through the fluid. A number of sensors are placed at different radial locations on the torque transmission disks to detect the strength of the electromagnetic field. Based on the strength of the electromagnetic field, the amount of torque being transmitted from the input shaft to the output shaft can be adjusted. Also disclosed is a distributed actuation architecture that uses this clutch system. The distributed actuation architecture allows for the use of a single drive motor in conjunction with multiple instances of the clutch system to actuate a mechanical linkage, such as a robotic arm.