Precision Actuator with Dual Linear Elements for Symmetrical Travel
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Solution Overview
Problem
Piezoelectric actuators used in active optics applications face challenges in achieving symmetrical travel around their initial position and maintaining low thermal expansion coefficients, leading to asymmetry and potential failure modes such as blocking in end positions.
Innovation Solution
A precision actuator design featuring two linear elements with controllable extensions in the same longitudinal direction, where one element's extension moves the actuator in one direction and the other's in the opposite direction, allowing for symmetrical travel and controlled thermal expansion, utilizing a common control system and deformation gauges for precise measurement and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a single piezoelectric actuator with pre-stressing is used, then the actuator can provide sufficient force, but the travel becomes asymmetric around the mechanical zero
Solution Approach 1:
The actuator is divided into two independent linear elements (first and second elements) that can be controlled separately. Each element is attached to different components (base and intermediate structure) and can produce independent displacements, allowing symmetric travel around the mechanical zero while maintaining sufficient force through combined operation.
2Stability of the object's composition
If the actuator operates with asymmetric travel, then the initial position can be maintained, but the center-shift requires significant voltage offset
Solution Approach 1:
The invention intentionally introduces asymmetry in the form of an intermediate structure that is not symmetrically positioned between the base and output interface. This asymmetric intermediate structure, combined with two independently controllable linear elements, enables symmetric travel around the mechanical zero without requiring voltage offset, as each element can be controlled to produce equal but opposite displacements.
3Measurement precision
If conventional piezoelectric materials are used, then the actuator can achieve nanometer precision, but the coefficient of thermal expansion remains significant
Solution Approach 1:
The actuator employs a composite structure consisting of two different linear elements (piezoelectric material and shape memory alloy) with different thermal expansion characteristics. This composite approach allows the overall actuator to achieve low thermal expansion coefficient while maintaining nanometer precision, as the thermal expansion of one material can compensate for the other.
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 actuator achieves symmetrical travel around its initial position with high precision and stability, maintaining mechanical zero and robustness suitable for space applications, while being insensitive to temperature variations and reducing the risk of failure.
Implementation Method 1
The inverse piezoelectric effect is the property of deformation of a piezoelectric material when an electric field is applied to it. The inverse piezoelectric effect allows actuators to be designed.
Implementation Method 2
deformation gauges for precise measurement and feedback
Data Source
AI summary
A nanometer-scale precision actuator comprises a base, an intermediate structure, an output interface, and two linear elements producing a controllable extension in the same longitudinal direction, each between a first and a second end. A first of the two elements has a first end fixed onto the intermediate structure and a second end fixed onto the base, a second of the two elements has a first end fixed onto the intermediate structure and a second end fixed to the output interface. The base and the intermediate structure are positioned in such a manner that the controllable extension of the second element produces a displacement of the actuator in a first direction and the controllable extension of the first element produces a displacement of the actuator in a second direction, opposite to the first direction, with respect to the base.