Flexible Pivot Mechanism for Large Rotation With High Stiffness
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Solution Overview
Problem
Existing pivot mechanisms fail to achieve a wide angular range with sufficient stiffness and precision due to overconstraints, non-linearity, and vulnerability to vibrations, especially when trying to cover long strokes or prevent torsion and axial displacement.
Innovation Solution
A pivot mechanism with flexible connections and intermediary junctions separated by expansion slots, connected by coupling members that prevent out-of-plane and lateral movements, providing a near-isostatic mechanism with high stiffness and resistance to vibrations, allowing for a greater angular range through parallel kinematics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If flexible elements are used to allow large angular rotation, then angular stroke is improved, but stiffness deteriorates
Solution Approach 1:
The pivot mechanism is divided into multiple independent kinematic chains connected in parallel between the fixed base and mobile element. Each chain contains flexible elements that can deflect independently, allowing the system to achieve large angular strokes while maintaining overall stiffness through the parallel configuration. The intermediary junctions are also segmented with expansion slots to accommodate rotational movement.
Solution Approach 2:
The patent transitions from serial stacking of simple pivots to a parallel kinematic configuration where multiple kinematic chains work simultaneously. This dimensional change in the system architecture allows the mechanism to achieve both large angular rotation and high stiffness by distributing the mechanical load across multiple parallel paths rather than accumulating compliance through series connections.
2Length of moving object
If intermediate connections are non-coupled to allow internal degrees of freedom, then angular range is improved, but resistance to vibrations deteriorates
Solution Approach 1:
The intermediary junctions connecting multiple kinematic chains are merged into a single rigid structure with expansion slots. This merging eliminates internal degrees of freedom at the intermediate connections while still allowing the overall mechanism to achieve large angular range through the deflection of flexible elements in each parallel chain. The rigid merged structure provides resistance to vibrations while the expansion slots accommodate the necessary rotational movement.
3Strength
If rigid couplings are used at intermediate levels to prevent torsion, then stiffness is improved, but angular stroke deteriorates
Solution Approach 1:
The rigid coupling is applied locally at the intermediary junctions where it is needed to prevent torsion and maintain stiffness, while the flexible elements in each kinematic chain are designed with appropriate compliance to allow the necessary angular stroke. The expansion slots in the intermediary junctions provide local flexibility to accommodate rotation without compromising the overall rigid coupling structure.
4Length of moving object
If multiple simple pivots are stacked serially to increase angular range, then angular stroke is improved, but precision deteriorates
Solution Approach 1:
The patent fundamentally changes the system architecture from serial to parallel configuration. Instead of stacking pivots in series where errors accumulate, multiple kinematic chains are arranged in parallel, each contributing to the overall angular stroke while the rigid intermediary junctions ensure that all chains move together precisely. This parallel architecture prevents error accumulation and maintains precision even with large angular ranges.
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 mechanism achieves a significant increase in angular stroke while maintaining high stiffness and resistance to vibrations, with a stiffness ratio of up to 30,000, and can be stacked without loss of performance, ensuring precise rotational guiding and robustness.
Implementation Method 1
a mobile element connected to a fixed element through flexible connections; with the flexible elements being configured so as to guide the mobile element according to a rotational movement
Implementation Method 2
each intermediary junction being separated from the adjacent intermediary junctions by an expansion slot, the expansion slot being configured to expand during the rotation of the mobile element, so that the latter can pivot according to a second angular amplitude that is greater than a first angular amplitude
Data Source
AI summary
A pivot mechanism for guiding in rotation comprises a mobile element connected to a fixed element through flexible connections; with the flexible elements being configured to guide the mobile element according to a rotational movement in a plane, around a pivoting axis perpendicular to the plane; with each of the flexible connections comprising an intermediary junction provided with an expansion slot, the expansion slot being configured to expand during the rotation of the mobile element, so that the mobile element can pivot according to a second angular amplitude that is greater than a first angular amplitude achieved without said expansion slot; with the intermediary junctions being connected to one another by a coupling member; each of the coupling members being configured so as to prevent a movement out of the plane and a lateral movement in the plane of the mobile element. The pivot mechanism has a very high rotational amplitude.