Preloaded Three-Flexure Pivot for Tunable Force Sensing
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Solution Overview
Problem
Existing flexure pivot mechanisms for force measurement are complex, require multiple flexures, and suffer from sensitivity to gravity direction and non-linear response, making them difficult to balance and adjust.
Innovation Solution
A flexure pivot system using three flexures (first, second, and third flexures) with a preloading system to adjust stiffness, allowing for tunable sensitivity and bistability, enabling use as a force sensor, torque limiter, programmable mechanical memory, or accelerometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple flexures are used to construct the suspension mechanism, then the device can achieve force measurement capability, but the construction becomes complicated and requires a large number of individual flexures
Solution Approach 1:
The patent combines multiple flexures into an integrated suspension mechanism where the first, second, and third flexures work together as a unified structure. This merging approach maintains the force measurement capability while reducing construction complexity by optimizing the arrangement and integration of flexure elements rather than using a large number of separate components.
Solution Approach 2:
The suspension mechanism is designed to perform multiple functions: it provides force measurement capability, supports the lever, enables rotational movement, and maintains structural stability. By making the suspension mechanism multi-functional, the patent reduces the need for separate components, thereby simplifying construction while preserving measurement precision.
2Reliability
If the rigid lever is balanced, then sensitivity to gravity direction is reduced, but it becomes difficult to balance and linearity of response improves only partially
Solution Approach 1:
The patent employs a preloading system that applies a force with a component substantially coaxial with the third flexure to pre-stress the suspension mechanism. By adjusting the preload parameter, the system can compensate for gravity effects and improve linearity of response without requiring complex balancing procedures. This parameter-based adjustment simplifies the balancing process while enhancing reliability.
Solution Approach 2:
The suspension mechanism is designed with flexible elements that can dynamically adapt to gravitational forces. The flexures allow the mechanism to accommodate gravity-induced deformations while maintaining measurement accuracy, reducing the need for static balancing and simplifying the overall design.
3Stability of the object's composition
If the stiffness of the pivot is increased, then the angular sensitivity of the lever to applied force is reduced, but the system becomes less sensitive for force sensing applications
Solution Approach 1:
The patent employs a preloading system that can dynamically adjust the stiffness characteristics of the suspension mechanism. By varying the preload force applied to the third flexure, the system can optimize the balance between pivot stability and angular sensitivity according to specific application requirements, enabling tunable performance for different force sensing scenarios.
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 system simplifies construction, improves sensitivity and linearity, and allows for adjustable threshold detection, enhancing its functionality as a force or acceleration sensor.
Implementation Method 1
a first flexure extending from said frame to a junction with said lever; a second flexure extending from said frame to said junction
Data Source
AI summary
Disclosed is a flexure pivot based system being one of: a force sensor, a force limiting device arranged to exert a predetermined threshold force, a torque limiting device arranged to exert a predetermined threshold torque, a programmable mechanical memory, or an accelerometer, the flexure pivot based system including a substantially rigid frame supporting a lever by a suspension mechanism including: a first flexure extending from the frame to a junction with the lever; a second flexure extending from the frame to the junction at a first non-zero angle to the first flexure in a neutral position of the suspension mechanism; and a third flexure extending from the junction to a preloading system at a second non-zero angle to the first flexure and/or the second flexure in the neutral position, the preloading system applying a force in a direction substantially coaxial with the third flexure.