Passive Haptic Interface With Multi-Pitch Magnetic Indexing
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Solution Overview
Problem
Existing passive haptic interfaces face challenges in achieving high indexing resolutions and efficient miniaturization due to limitations in torque and magnetic field interactions, leading to bulky and costly devices.
Innovation Solution
A passive haptic interface design that utilizes a first mobile element and a second fixed element, each with fewer magnetic poles than the number of notches felt, creating a periodic force with a period less than the smallest of the pitches, allowing for a greater number of notches without increasing the number of magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of magnetic poles is increased to achieve high indexing resolution, then the resolution is improved, but the device size and complexity increase
Solution Approach 1:
The patent combines multiple magnetic poles into a single integrated magnet structure. The mobile element includes a magnet with multiple poles (e.g., 4 poles) that interacts with multiple ferromagnetic protuberances on the fixed element, creating multiple indexing positions without requiring multiple separate magnets. This merging approach achieves high resolution (e.g., 12 indexing positions from 4 poles interacting with 3 protuberances per pole) while reducing device complexity and size compared to using individual magnets for each indexing position.
2Volume of moving object
If the cross-section of the magnet is reduced to enable miniaturization, then the device size is reduced, but the torque and indexing resistance are lost
Solution Approach 1:
The patent segments the magnetic interaction into multiple discrete interaction points between the magnet poles and ferromagnetic protuberances. Instead of relying on a single large magnet cross-section, the system creates multiple localized magnetic interactions (e.g., 4 poles × 3 protuberances = 12 interaction points). This segmentation allows the use of smaller individual magnetic elements while maintaining cumulative torque through the multiplication of interaction points, thereby enabling miniaturization without significant loss of torque.
Solution Approach 2:
The patent employs periodic magnetic interactions as the mobile element rotates, creating a periodic torque pattern with multiple peaks corresponding to the indexing positions. The periodic arrangement of magnetic poles and ferromagnetic protuberances generates repeated attractive forces at regular angular intervals, ensuring that the average torque remains sufficient even though individual interaction forces are smaller due to reduced magnet cross-section. This periodic action maintains indexing resistance across the full rotation range.
3Measurement precision
If the number of protuberances on the metallic element is increased to achieve high resolution, then the indexing resolution is improved, but the magnet cross-section must be reduced which loses torque
Solution Approach 1:
The patent merges the functions of multiple magnets into a single multi-pole magnet structure that simultaneously interacts with multiple ferromagnetic protuberances. This allows the system to achieve high resolution (e.g., 12 indexing positions) by having one magnet with 4 poles interact with 3 protuberances per pole, rather than using multiple separate magnets. The merged structure maintains sufficient torque by concentrating magnetic flux through the multi-pole design while keeping the overall magnet cross-section smaller than would be required if separate magnets were used for each indexing position.
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 economical industrial production of haptic interfaces with improved torque and resolution, facilitating miniaturization and reducing production costs while maintaining a passive operation without electrical consumption.
Implementation Method 1
a magnetic element (6), which creates a magnetic field
Implementation Method 2
The mobile element (1) and the fixed element (2) are made respectively of ferromagnetic material and create between them a periodic effort
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a passive haptic interface comprising a first element (1) which is rotatably movable about an axis (3) or translatably movable along an axis (3), the first movable element (1) rotating or moving opposite a second fixed element (2), the first movable element (1) having a first plurality of magnetic poles spaced periodically at a pole pitch Ps and in the direction of movement, the second fixed element (2) having 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 being created by the magnetic interaction between the first movable element (1) and the second fixed element (2) 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.