Hybrid SMA Artificial Muscle Actuator With Electrode Alignment Aids
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Solution Overview
Problem
Current robotic technologies relying on rigid components, such as servomotors, face limitations due to their weight-to-power ratio, and artificial muscles with fluid-based actuators have limited force exertion capabilities.
Innovation Solution
A hybrid actuation device combining a shape memory alloy wire and an artificial muscle with an electrode pair and alignment aids, where the SMA wire contracts to draw plates together, and the artificial muscle's electrostatic attraction holds the device in an actuated state, enhancing both actuation force and displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If artificial muscles with fluid-based actuators are used, then the device achieves soft actuation and versatility, but the force exertion capability is limited
Solution Approach 1:
The patent combines two different actuation mechanisms - shape memory alloy (SMA) wires and electrostatic artificial muscles - into a hybrid actuation device. The SMA wire provides strong contraction force to close the plate pair, while the electrostatic artificial muscle provides holding force to maintain the closed state, thereby achieving both high force capability and soft actuation characteristics
Solution Approach 2:
The invention uses composite material approaches by integrating metal SMA wires with dielectric fluid-filled artificial muscle components. This composite structure allows the device to leverage the high strength and contractility of SMA materials while incorporating the compliant, soft characteristics of the artificial muscle components
2Force
If rigid components like servomotors are used, then the device achieves high force output, but the weight-to-power ratio becomes unfavorable
Solution Approach 1:
The patent replaces traditional rigid mechanical actuation systems (servomotors) with a hybrid system combining SMA wire actuation and electrostatic artificial muscle holding. This substitution eliminates heavy mechanical components while maintaining high force output capability through the SMA wire's strong contraction and the artificial muscle's electrostatic holding force
Solution Approach 2:
The invention changes the actuation parameters from continuous mechanical rotation (servomotors) to discrete phases: SMA wire contraction for closing and electrostatic field application for holding. This parameter change enables high force output with significantly reduced weight by using material property changes and electromagnetic fields instead of heavy mechanical systems
3Productivity
If electrode pairs in artificial muscles are positioned close to plates, then actuation efficiency improves, but manufacturing alignment becomes difficult
Solution Approach 1:
The patent introduces alignment aids as intermediary components between the plates and the artificial muscle electrode pairs. These alignment aids ensure proper positioning and alignment of the electrodes relative to the plates during assembly, thereby achieving the necessary manufacturing precision without compromising actuation efficiency
Solution Approach 2:
The alignment aids are pre-positioned or pre-assembled to establish correct electrode alignment before the artificial muscle is fully assembled and activated. This preliminary alignment action ensures that when the device is operated, the electrodes are properly positioned for optimal actuation efficiency, while the alignment process itself is simplified during manufacturing
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 hybrid actuation device achieves improved actuation force and displacement by combining the contraction force of the SMA wire with the electrostatic attraction of the artificial muscle, providing a more efficient and versatile robotic actuation mechanism.
Implementation Method 1
at least one shape memory alloy wire coupled to the first plate and configured to draw the first plate and the second plate together
Implementation Method 2
an electrode pair configured to electrostatically attract and hold the hybrid actuation device in the actuated state
Data Source
AI summary
A hybrid actuation device that includes a first plate coupled to a second plate, a shape memory alloy wire coupled to the first plate, and an artificial muscle positioned between the first plate and the second plate. The artificial muscle includes a housing having an electrode region and an expandable fluid region, a first electrode and a second electrode each disposed in the electrode region of the housing and a dielectric fluid disposed within the housing. The expandable fluid region of the housing is positioned apart from a perimeter of the first plate and the second plate. A first alignment aid is positioned between the first plate and the first electrode, the first alignment aid having an inner surface facing the first plate and an outer surface facing the first electrode.