Hybrid Actuator Alignment Aids for High-Force Soft Actuation
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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 limited force exertion, necessitating improved actuation devices that combine the advantages of shape memory alloys and soft actuators.
Innovation Solution
A hybrid actuation device comprising 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
1Force
If rigid components such as servomotors are used for actuation, then actuation force and precision are improved, but weight-to-power ratio deteriorates
Solution Approach 1:
The patent combines shape memory alloy wires and artificial muscles in a hybrid actuation system. The SMA wires provide structural support and initial actuation force, while the artificial muscles provide additional actuation force and displacement. This merging of rigid and soft actuation mechanisms achieves high actuation force while maintaining a favorable weight-to-power ratio, as both components are lightweight compared to traditional servomotors.
Solution Approach 2:
The actuation system uses composite material structures, including the housing made from flexible material and the combination of metal SMA wires with polymer-based artificial muscles. This composite approach allows the system to achieve both the strength needed for actuation force and the lightness required for good weight-to-power ratio.
2Adaptability or versatility
If artificial muscles are used for actuation, then softness and versatility are improved, but actuation force deteriorates
Solution Approach 1:
The hybrid actuation system merges artificial muscles with SMA wires and rigid housing components. The artificial muscles provide softness and versatility for adapting to different tasks and environments, while the SMA wires and housing structure provide the additional actuation force needed. The alignment aids further enhance this combination by ensuring optimal force transmission from both actuation mechanisms.
Solution Approach 2:
The alignment aids act as intermediaries between the actuation mechanisms and the load. These components ensure that the forces generated by both the SMA wires and artificial muscles are transmitted efficiently to the housing and load, maximizing the combined actuation force while preserving the softness and versatility of the artificial muscle components.
3Force
If continuous SMA wire contraction is used to maintain actuated state, then actuation force is maintained, but energy consumption increases
Solution Approach 1:
The artificial muscles in the hybrid system provide a self-sustaining mechanism for maintaining the actuated state. Once activated, the artificial muscles can maintain force output without continuous input, allowing the SMA wires to be deactivated. This self-service capability of the artificial muscles eliminates the need for continuous energy input to maintain position, significantly reducing overall energy consumption while maintaining actuation force.
Solution Approach 2:
The system uses periodic or pulsed activation of the SMA wires rather than continuous contraction. The SMA wires are activated briefly to transition the system to the desired state, then the artificial muscles maintain the position. This periodic action pattern reduces energy consumption compared to continuous SMA wire contraction, while the artificial muscles provide the sustained force needed to maintain the actuated state.
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, allowing for efficient mechanical work while reducing the need for continuous SMA wire contraction.
Implementation Method 1
a shape memory alloy wire coupled to the first plate... actuating a shape memory alloy wire that is coupled to a first plate of a plate pair further including a second plate, thereby drawing the first plate and the second plate together
Implementation Method 2
an artificial muscle positioned between the first plate and the second plate... applying a voltage to the electrode pair, thereby electrostatically attracting the first electrode and the second electrode together to 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.