Orthogonal Flexure Linear Actuator for Precision Motion
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Solution Overview
Problem
Conventional linear motion guidance systems face issues such as friction, wear, maintenance requirements, weight, cost, limited deflection, parasitic motion, reduced stiffness, and manufacturing complexity, which hinder their application in precision and accuracy-demanding scenarios.
Innovation Solution
A linear actuator design utilizing orthogonally arranged flexures with extension elements that allow for large deflections, minimize parasitic motion, and enhance stiffness, while maintaining a compact and cost-effective structure, by using a configuration of base and arm flexures that restrict motion to a linear axis and incorporate stiffeners to prevent off-axis deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional guidance systems (rails and carriages) are used, then load capacity is sufficient, but friction is high and accuracy is limited
Solution Approach 1:
The patent replaces conventional mechanical guidance systems (rails, carriages, rolling elements) with a compliant mechanism using flexures. The flexure-based parallel mechanism eliminates sliding and rolling friction by using elastic deformation for motion, thereby achieving high positioning accuracy without frictional losses.
Solution Approach 2:
The patent changes the fundamental operating parameter from rigid mechanical contact to elastic deformation. By designing flexures with appropriate geometry and material properties, the system achieves motion through controlled elastic bending, which inherently provides frictionless operation and high precision.
2Weight of moving object
If conventional guidance systems are used, then structural strength is sufficient, but weight is excessive
Solution Approach 1:
The patent employs thin flexure elements instead of massive rigid components. The flexures are designed with optimized thickness and geometry to provide sufficient load-bearing capacity through elastic deformation while maintaining minimal weight, replacing heavy rails and carriages with lightweight compliant structures.
Solution Approach 2:
The patent utilizes composite construction in the flexure elements, combining materials with high specific strength and stiffness. This allows the flexures to achieve the necessary mechanical performance for load support while keeping the overall mass of the moving components minimal.
3Measurement precision
If flexure systems are used, then friction is reduced, but parasitic motion increases
Solution Approach 1:
The patent divides the motion system into multiple independent flexure elements arranged in a parallel mechanism configuration. Each flexure handles specific degrees of freedom, and their coordinated deformation ensures that motion occurs only in the desired linear direction, eliminating parasitic movements through geometric constraint.
Solution Approach 2:
The patent uses a three-dimensional arrangement of flexure elements where orthogonal sets of flexures constrain motion in multiple directions simultaneously. This spatial configuration ensures that the moving plate can only translate along the intended axis, preventing arc-like or orthogonal parasitic motions.
4Ease of manufacture
If flexure systems are used, then manufacturing cost is reduced, but stiffness in constraint directions is insufficient
Solution Approach 1:
The patent designs the flexure system to exhibit dynamic stiffness characteristics where the compliant elements provide sufficient stiffness in constraint directions during operation. The flexures are geometrically optimized to be stiff where needed (constraint directions) while remaining compliant in the motion direction, achieving both performance and manufacturability.
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 solution provides a lightweight, low-friction, high-stiffness, and cost-effective linear motion guidance system with minimal parasitic motion, enabling precise and accurate linear displacement with reduced maintenance needs, suitable for precision applications.
Implementation Method 1
Flexures inherently have virtually no friction when used in the elastic region of the flexure material
Implementation Method 2
the first and second set of flexures comprise an extension element that has stored length that enables the flexure to extend and therefore maintain a linear plane of motion along the axis of motion
Data Source
AI summary
A linear actuator provides linear displacement of an actuator plate. The linear actuator includes a set of base flexures that extend from a base plate to an actuator plate and a set of arm flexures that extend from a base arm to an actuator arm. The base arm of the base frame extends up perpendicularly from the base plate and the actuator arm, of the actuator frame, extends perpendicularly from the actuator plate. A base frame and actuator frame may be elbows that are arranged to form a box with the base flexures and arm flexures extending orthogonally within the cavity of the box. A flexure may include an extension element such as a pleated portion of the flexure that has stored length that enables the flexure to extend to increase the linear displacement region. The arm flexures prevent the base flexures from following a radius of motion.