Resonant Actuator Beat Frequency Haptics
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Solution Overview
Problem
Haptics actuators in portable and wearable devices face challenges in achieving human-perceptible vibrations with small mass and high stiffness without requiring a large driving force, as they either become bulky and fragile at low resonance frequencies or have resonance frequencies outside the human perceptible range.
Innovation Solution
A haptics system with a resonant actuator that receives a mixed driving signal with a first frequency about its resonance frequency and a second frequency between 0 Hz and 500 Hz, allowing the actuator to vibrate at a perceptible beat frequency without a large driving force, utilizing a frequency mixer and oscillators to generate these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonant actuator uses large mass and low stiffness to achieve resonance at low frequencies for human perceptibility, then the vibration frequency is within human perceptible range, but the actuator becomes bulky and fragile
Solution Approach 1:
The patent changes the resonance frequency parameter of the actuator from low frequency (within human perceptible range) to high frequency (ultrasonic range, >1 kHz). This parameter change allows the use of small mass and high stiffness materials while still achieving perceptible vibrations through frequency modulation techniques, thereby resolving the contradiction between human perceptibility and actuator robustness
Solution Approach 2:
The patent applies periodic modulation of the ultrasonic vibrations at audible frequencies (0-500 Hz). By modulating the high-frequency ultrasonic vibrations at lower frequencies, the actuator creates perceptible tactile sensations without requiring the actuator itself to vibrate at those low frequencies, thus maintaining robustness while achieving human perceptibility
2Strength
If the resonant actuator uses small mass and high stiffness to achieve compactness and robustness, then the actuator becomes compact and robust, but the resonance frequency moves outside the human perceptible range
Solution Approach 1:
The patent modulates the ultrasonic vibrations at audible frequencies to create perceptible tactile sensations. The high-frequency ultrasonic carrier signal is modulated at frequencies within the human perceptible range (0-500 Hz), allowing the actuator to maintain high frequency operation for robustness while delivering perceptible vibrations through the modulation envelope
Solution Approach 2:
The patent utilizes mechanical vibration at ultrasonic frequencies combined with frequency modulation. The resonant actuator vibrates at its high natural frequency (ultrasonic range), and through frequency modulation, creates sidebands or envelope variations that fall within the human perceptible range, achieving both robustness and perceptibility
3Reliability
If the resonant actuator vibrates below its resonance frequency to achieve perceptible displacement amplitude, then the displacement is perceptible, but a large driving force is required
Solution Approach 1:
The patent drives the resonant actuator at or near its resonance frequency (ultrasonic range) to achieve maximum displacement amplitude with minimum driving force. The resonant vibration condition naturally amplifies the displacement response, eliminating the need for large driving forces that would be required if vibrating below resonance frequency
Solution Approach 2:
The patent changes the operating frequency parameter to match the actuator's natural resonance frequency (ultrasonic range). This parameter change exploits the resonant amplification effect, which provides high displacement amplitude with low driving force, thereby resolving the contradiction between perceptible displacement and driving force magnitude
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
Enables robust, compact haptics systems capable of providing perceptible tactile sensations with reduced power requirements, as the resonant actuator is driven at its resonance frequency, amplifying displacement amplitude and modulating it with a perceptible frequency for enhanced tactile feedback.
Implementation Method 1
the resonant actuator is configured to receive a mixed driving signal that includes a first mixed driving signal portion and a second mixed driving signal portion. The first mixed driving signal portion has a first mixed frequency about the resonance frequency of the resonant actuator
Implementation Method 2
a frequency mixer and oscillators to generate these signals... the first mixed frequency is equal to a sum of the first frequency and the second frequency, while the second mixed frequency within the mixed driving signal is equal to a difference between the first frequency and the second frequency
Implementation Method 3
the resonant actuator is driven at its resonance frequency, amplifying displacement amplitude and modulating it with a perceptible frequency for enhanced tactile feedback
Data Source
AI summary
The present disclosure relates to a haptics system with a resonant actuator that has a non-perceptible resonance frequency and is capable of vibrating with a perceptible beat frequency to create a tactile sensation without a large driving force. Within the disclosed haptics system, the resonant actuator is configured to receive a mixed driving signal that includes a first mixed driving signal portion and a second mixed driving signal portion. The first mixed driving signal portion has a first mixed frequency about the resonance frequency of the resonant actuator, and the second mixed driving signal portion has a second mixed frequency that is between 0 Hz and 500 Hz. The first mixed frequency is at least several times greater than the second mixed frequency.