Flexible Pivot Structure for Large Rotation and Stiffness Control
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Solution Overview
Problem
Existing multistage flexible pivots face challenges in increasing rotational range without compromising axial and radial stiffness, leading to potential center shift issues and vibration mode decoupling difficulties in space applications.
Innovation Solution
The introduction of flexible connection means, specifically a set of spokes intercalated between the cylinders, which connect the first and second interface structures, allowing for increased rotational range without lengthening the pivot axially, and the use of flexible attachment means to adjust radial stiffness independently, thereby reducing center shift and improving vibration decoupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the number of stages in a flexible pivot is increased to extend the rotational range, then the rotational range is improved, but the radial and axial stiffness deteriorate, leading to center shift issues
Solution Approach 1:
The patent introduces flexible connection means (spokes) that extend in the radial direction to connect the first and second interface structures, thereby increasing the rotational range without increasing the axial length. This dimensional approach allows the pivot to achieve larger rotation angles while maintaining axial stiffness through the compact axial footprint.
Solution Approach 2:
The patent employs flexible attachment means at the connection points between the spokes and interface structures, allowing local flexibility to accommodate rotation while the main structural elements (cylinders and spokes) maintain rigid properties for stiffness. This localized flexibility enables large rotational ranges without compromising overall structural integrity.
2Strength
If conventional bearings with sliding or rolling elements are used, then the mechanical strength is improved, but wear particles are generated that can jam the mechanism and migrate to optical components
Solution Approach 1:
The patent replaces conventional mechanical bearings with a flexible pivot mechanism that uses elastic deformation of the connecting members (spokes and legs) to enable rotation. This substitution eliminates sliding or rolling contact, thereby preventing wear particle generation while maintaining the necessary mechanical strength and rotational capability.
3Strength
If conventional bearings are used, then the mechanical strength is improved, but noise is generated that reduces fine-pointing performance
Solution Approach 1:
The patent replaces noise-generating conventional bearings with a flexible pivot that operates through silent elastic deformation. The flexible connecting members deform elastically during rotation without the mechanical contact and impact that produce noise in conventional bearings, thereby maintaining fine-pointing performance while preserving mechanical strength.
4Shape
If the axial length of the pivot is increased to accommodate more stages for larger rotational range, then the rotational range is improved, but the axial stiffness deteriorates
Solution Approach 1:
The patent achieves extended rotational range by utilizing the radial dimension through flexible spokes that connect interface structures radially, rather than increasing axial length by stacking multiple stages axially. This dimensional reconfiguration allows large rotation angles while maintaining a compact axial footprint and preserving axial stiffness.
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
This solution enhances the rotational range of the flexible pivot while maintaining axial stiffness, reduces center shift, and allows for custom tuning of radial stiffness to effectively decouple external micro-vibrations, improving the overall performance in space applications.
Implementation Method 1
a set of flexible connecting members for connecting the first and the second stages, each flexible connecting member comprising a pair of legs and a cross member joining the legs... The first and the second stages are connected by three flexible connecting members causing the pivot to exhibit 3-fold rotational symmetry
Data Source
AI summary
A flexible pivot includes a first stage including a first cylinder and interface structure and a second stage including a second cylinder and interface structure in axial alignment with those of the first stage. Flexible connecting members are arranged for connecting the first and the second stages. Each flexible connecting member includes a pair of legs and a cross member joining the legs, each leg extending in a direction transverse to the axis of the cylinders, the legs being attached to the first and the second cylinders respectively. The first cylinder and the first interface structure are concentric. Flexible spokes are attached to the first cylinder by one end and to the first interface structure by the other. Each spoke extends in a direction transverse to the axis of the cylinders. Finally, the second stage includes flexible connection unit arranged to connect the second cylinder to the second interface structure.