Fault-Tolerant Clevis Pivot Joint for Motion Simulator Load Paths
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Solution Overview
Problem
Motion simulators with hexapod structures face challenges in providing fault-tolerant connections that maintain stability and redundancy across multiple degrees of freedom, particularly in the event of actuator failures, which can lead to catastrophic system failures.
Innovation Solution
The design incorporates a connection joint with a platform joint and base joint featuring a clevis, pin, and axel configuration that includes primary and secondary clearance differences to ensure fault tolerance, allowing the system to maintain functionality even if primary load paths fail by engaging secondary load paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single load path is used in the connection joint, then the device complexity is reduced, but the reliability decreases due to catastrophic failure risk
Solution Approach 1:
The connection joint is segmented into multiple independent load paths: a primary load path through the clevis pin and axel, and a secondary load path through the fault retaining protrusions and secondary bearing surfaces. This segmentation allows the system to maintain functionality even if one path fails, directly resolving the contradiction between reliability and complexity by creating modular redundancy.
Solution Approach 2:
The design incorporates fault retaining protrusions and secondary bearing surfaces that are prepared in advance but remain dormant during normal operation. These elements act as pre-positioned backup mechanisms that only engage when the primary load path fails, providing beforehand cushioning against catastrophic failure without adding operational complexity.
2Manufacturing precision
If primary and secondary clearance differences are reduced for tighter tolerances, then the manufacturing precision improves, but the device complexity increases due to tighter tolerance requirements
Solution Approach 1:
Different clearance tolerances are applied locally to different functional regions: the primary load path uses tighter clearance differences (first and second clearance differences) for precision, while the secondary load path uses larger clearance differences (third and fourth clearance differences) that are easier to manufacture. This local differentiation resolves the contradiction by optimizing precision where needed while simplifying manufacturing elsewhere.
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 configuration provides enhanced redundancy and fault tolerance, preventing catastrophic failures by ensuring continued operation even if primary load paths fail, thus improving the reliability and safety of motion simulators.
Implementation Method 1
a platform joint (15) having at least two degrees of freedom; the platform joint having a first pivot axis (20) and a second pivot axis (23) intersecting the first pivot axis
Data Source
AI summary
A motion simulator comprising a base (102), a platform (104), and a plurality of linear actuators (108) connecting the base and platform via a joint having at least two degrees of freedom, the joint (15) comprising an actuator clevis comprising first and second side lugs having first and second lug openings retaining a clevis pin, an anchor clevis retaining an axel comprising first and second axel fault retaining protrusions and an axel opening receiving the clevis pin and having primary and secondary axel passage sections, the first side lug opening, pin and first axel fault retaining protrusion having a primary lug radial clearance difference between a primary inner radius of the first lug opening and an outer radius of the pin that is less than a secondary lug radial clearance difference between a secondary lug inner radius of the first lug opening and a retaining outer radius of the first axel fault retaining protrusion.