Vibrotactile Actuator Using Halbach Array and Linear Motor
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Solution Overview
Problem
Existing vibrotactile actuators are thick and limited to single frequency, unable to generate a wide range of vibrations, which restricts their use in haptic applications that require rich tactile sensations.
Innovation Solution
A vibrotactile actuator utilizing a Halbach network linear motor with elastic guide means, transforming translational movements into haptic vibrations, allowing for a wide range of amplitudes and frequencies and maintaining a small thickness for versatile device integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional vibrotactile actuators (eccentric mass or resonance-based) are used, then they can generate vibrations, but they are relatively thick and limited to single frequency
Solution Approach 1:
The patent replaces traditional mechanical vibration generation systems (eccentric masses, springs) with an electrodynamic linear motor system. This substitution enables multi-frequency vibration capability while reducing actuator thickness, as the electromagnetic system can generate vibrations across a broad frequency range without the mechanical constraints of rotating masses or spring resonance frequencies.
Solution Approach 2:
The patent employs a dynamic control system that can vary the frequency and amplitude of vibrations in real-time. By using a linear motor driven by variable frequency current, the actuator can adapt its vibration characteristics dynamically, providing rich tactile sensations across multiple frequencies rather than being locked to a single resonant frequency.
2Length of moving object
If radial magnetic structure with symmetry is used in linear motor, then the structure is simple, but it causes magnetic field leakage requiring mild steel armature that increases thickness
Solution Approach 1:
The patent employs an asymmetric Halbach array configuration for the permanent magnets, where adjacent magnets have polarizations oriented at different angles (e.g., 0°, 90°, 180°, 270°). This asymmetric arrangement concentrates magnetic field lines on one side of the array while canceling leakage on the other side, eliminating the need for thick mild steel armatures and reducing overall actuator thickness.
3Power
If Halbach array is used to concentrate field lines, then magnetic field efficiency improves, but magnet arrangement complexity increases
Solution Approach 1:
The Halbach array is implemented by dividing the magnet structure into discrete segments or modules, where each segment contains magnets arranged in the characteristic Halbach pattern. This segmentation allows the complex magnetic field concentration to be achieved through repeated modular units, simplifying manufacturing while maintaining the power efficiency benefits of the Halbach configuration.
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 solution enables the generation of a wide range of vibrations, providing rich tactile sensations while maintaining a compact thickness, suitable for various haptic applications.
Implementation Method 1
the sets of coils 12, 13 create, under the effect of an electric current passing through them, a horizontal Laplace force between each plane of the sets of coils and the plane of the network of magnets
Implementation Method 2
elastic guiding means (140) transforming said translational movements into vibratory movements
Implementation Method 3
transform an electrical signal, generated by a machine, into a vibratory signal perceptible by touch
Data Source
Figure 1A~2B
Figure 3A~8
Figure 3B~12B
AI summary
The invention relates to a vibrotactile actuator comprising a network (120) of flat electromagnetic coils positioned contiguously in a plane (PB), the said network (120) of coils being able to generate a Laplace force under the effect of an electric current passing through the said network (120) of coils, a network (110) of permanent magnets assembled linearly in a plane (PA) parallel to the plane of the network (120) of coils and forming a Halbach network generating magnetic field lines oriented towards the network (120) of coils, an electromagnetic interaction between the current lines passing through the network (120) of coils and the magnetic field lines giving rise, as a result of the Laplace force, to relative translational movement between the network (120) of coils and the network (110) of magnets, and elastic guide means (140) for generating haptic vibrations from the relative translational movements of the network (120) of coils and the network (110) of magnets.