Passive Haptic Interface Using Pole-Pitch Mismatch for Fine Indexing
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Solution Overview
Problem
Existing haptic interfaces face challenges in miniaturization and achieving high indexing resolutions due to high localized magnetic forces and size limitations, leading to poor torque/magnet volume ratios and industrialization difficulties, while most require electrical power or complex assembly.
Innovation Solution
A passive haptic interface design that uses a movable and fixed element with fewer magnetic poles than notches, utilizing periodic magnetic pole distributions to create a variable stress without electrical power, allowing for simpler and more economical industrial production and integration of a position sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional magnetic indexing devices use one or two magnets with high localized attractive force, then indexing is achieved, but the torque/magnet volume ratio is poor and device size cannot be miniaturized
Solution Approach 1:
The invention divides the magnetic field into multiple discrete magnetic poles (at least three) distributed around the circumference of the movable element. This segmentation allows the magnetic force to be distributed across multiple interaction points with the fixed element's teeth, creating multiple stable equilibrium positions (notches) while maintaining adequate torque with smaller magnet volume.
Solution Approach 2:
The invention combines multiple magnetic poles into a single movable element structure that interacts with a corresponding fixed element. This merging approach creates a compact design where multiple magnetic interactions occur simultaneously within a small volume, achieving high indexing resolution without increasing overall device size.
2Measurement precision
If the number of protuberances on the metallic element is increased for higher resolution, then indexing resolution improves, but the magnet section must be reduced to prevent field interaction with neighboring protuberances, causing torque loss
Solution Approach 1:
The invention creates different local magnetic field characteristics at different angular positions around the movable element. Each magnetic pole creates a localized interaction zone with specific teeth on the fixed element, allowing high-resolution indexing without requiring the entire magnet structure to be large. The magnetic field strength is concentrated locally at each pole-teeth interaction point.
3Measurement precision
If a large number of magnets are used to produce a large number of notches, then indexing resolution improves, but device complexity and assembly difficulty increase
Solution Approach 1:
The invention merges multiple magnetic poles into integrated movable and fixed element structures. Rather than using numerous separate magnet components, the design uses at least three magnetic poles distributed around the movable element that interact with a corresponding fixed element structure, reducing the number of discrete parts while achieving high indexing resolution.
4Measurement precision
If the pitch between teeth is reduced for higher resolution, then more notches can be achieved, but the magnet size must be reduced further, attenuating indexing resistance
Solution Approach 1:
The invention creates a dynamic magnetic interaction system where the movable element with multiple magnetic poles can achieve stable equilibrium positions at multiple discrete angular locations. The system maintains adequate indexing resistance by ensuring sufficient magnetic field strength at each interaction point, even when the pitch between teeth is reduced for higher resolution.
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 design enables the creation of a larger number of notches with fewer magnetic poles, facilitating miniaturization and economical production, while maintaining a strong haptic effect and allowing for position sensing without electrical power consumption.
Implementation Method 1
a periodic stress is created by the magnetic interaction between the first movable element and the second fixed element
Data Source
AI summary
A passive haptic interface includes a first element which is rotatably movable about an axis or translatably movable along an axis, the first movable element rotating or moving opposite a second fixed element. The first movable element has a first plurality of magnetic poles spaced periodically at a pole pitch Ps and in the direction of movement, and the second fixed element has a second plurality of magnetic poles periodically spaced at a pole pitch Pr and in the direction of movement, where Ps and Pr are different numbers. A periodic stress is created by the magnetic interaction between the first movable element and the second fixed element in a period Pt. The pole pitches Ps and Pr are chosen such that Pt is strictly less than the smallest of the pitches Ps and Pr.