Cross-Spring Actuator with SMA Wire for Precise Tilt and Rotation
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Solution Overview
Problem
Existing actuator designs often cause unwanted movement in directions other than the desired direction, leading to stress and inefficiencies due to unwanted torque and out-of-plane bending forces.
Innovation Solution
A cross-spring actuator design incorporating a first and second cross-spring element with spring arms crossing at a pivot point and connected by a shape-memory alloy (SMA) wire, allowing controlled movement relative to the pivot point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional actuator designs are used, then actuation function is achieved, but unwanted movement in directions other than the desired direction occurs causing stress and inefficiencies
Solution Approach 1:
The actuator is divided into multiple independent spring elements (first spring element, second spring element) that each handle specific movement constraints. This segmentation allows the system to independently control different degrees of freedom, constraining unwanted movements while maintaining desired actuation functionality.
Solution Approach 2:
The cross-spring mechanism acts as an intermediary between the actuation force and the moving component. The spring elements and pivot points work together to mediate the force transmission, converting linear actuation motion into rotational movement while automatically filtering out unwanted directional forces and torques.
2Manufacturing precision
If movement constraints are added to prevent unwanted motion, then actuation precision improves, but device complexity increases
Solution Approach 1:
Multiple spring elements are merged into a compact cross-spring configuration where the first and second spring elements share common pivot points and mounting locations. This merging achieves precise motion constraints through the geometric arrangement of the springs rather than through separate constraint mechanisms, reducing overall device complexity.
Solution Approach 2:
The cross-spring assembly serves multiple functions simultaneously: it provides the actuation spring force, constrains unwanted movements, defines the pivot point location, and guides the rotational motion. This multi-functionality eliminates the need for separate components for each function, maintaining simplicity while achieving precise motion control.
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 design constrains unwanted motion, providing precise control over tilt and rotation, minimizing stress and improving efficiency by allowing for controlled two-axis tilt and rotation.
Implementation Method 1
at least one shape-memory alloy (SMA) wire that is connected at a first end at a first end portion of the first cross-spring element or the second cross-spring element and connected at a second end at a second end portion of the first cross-spring element or the second cross-spring element
Data Source
AI summary
The present embodiments relate to a cross-spring actuator (CSA) and device designs that incorporate one or more cross-spring actuators. The CSA can include a first cross-spring element and a second cross-spring element that each have end portions. The CSA can also include a set of spring arms connecting the first cross-spring element and the second cross-spring element. The set of spring arms can be disposed at an angle such that each of the set of spring arms cross at a pivot point. The CSA can also include at least one shape-memory alloy (SMA) wire connected between end portions of any of the cross-spring elements. The CSA can be part of a two-axis tilt module, a serial rotational joint, a spine device, and a revolute joint device.