Electromagnetic Haptic Actuator Control for Harmonic-Free Vibration Decay
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Solution Overview
Problem
Existing haptic interface apparatuses generate harmonics when adjusting vibration attenuation periods, leading to uncomfortable touch operation feelings and abnormal noises due to superimposed harmonics on acceleration waveforms.
Innovation Solution
A control device and vibration presenting apparatus that utilize an electromagnetic actuator with a control mechanism to suppress harmonic generation by adjusting vibration attenuation periods through the application of specific sub-driving signals, such as sine waves, instead of square waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a square wave pulse is applied to the coil of the electromagnetic actuator to adjust the vibration attenuation period, then the vibration attenuation period can be extended or shortened, but a harmonic is superimposed on the acceleration waveform of vibration causing uncomfortable touch operation feeling and abnormal noise
Solution Approach 1:
The patent applies a sine wave or cosine wave signal instead of a square wave pulse to the coil of the electromagnetic actuator. This changes the waveform parameter from a discontinuous square wave to a continuous sinusoidal wave, which varies smoothly over time. The sinusoidal waveform avoids abrupt current changes that generate harmonics, thereby eliminating the harmful vibrations and abnormal noise while still effectively adjusting the vibration attenuation period.
2Duration of action of moving object
If a square wave pulse is applied to the coil, then the vibration attenuation period can be adjusted, but variations in current during pulse application and stopping cause harmonic generation
Solution Approach 1:
The patent changes the current waveform parameter from a square wave with abrupt transitions to a sinusoidal wave with smooth continuous variation. The sine or cosine function ensures that the current changes gradually without sudden jumps or discontinuities during application and cessation, eliminating the conditions that cause harmonic generation while maintaining reliable control over the vibration attenuation period.
3Duration of action of moving object
If a main driving pulse and kick-in/braking pulses are applied, then the vibration attenuation period can be controlled, but the square wave nature of these pulses generates harmonics on the acceleration waveform
Solution Approach 1:
The patent replaces all square wave pulses (main driving pulse, kick-in pulse, and braking pulse) with a continuous sinusoidal signal. This parameter change transforms the discontinuous pulsed control into a smooth oscillating control, eliminating the abrupt edges that generate harmonics. The sinusoidal signal maintains the ability to control vibration attenuation while removing the harmful harmonic interference from the acceleration waveform.
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 effectively suppresses harmonic generation, providing a more comfortable and noise-free touch operation experience by controlling the vibration attenuation periods of the electromagnetic actuator.
Implementation Method 1
an electromagnetic actuator that drives an operation device, which is supported in an elastically vibratable manner by an elastic support part, in one direction of a vibration direction of the operation device to vibrate the operation device
Implementation Method 2
an operation device, which is supported in an elastically vibratable manner by an elastic support part
Data Source
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AI summary
Provided is a control device controlling an electromagnetic actuator that drives an operation device, supported in an elastically vibratable manner by an elastic support part, in one direction of a vibration direction of the operation device to vibrate. The control device includes a circuit that applies a main driving signal to a coil of the electromagnetic actuator to start vibration of the operation device in response to a touch operation on the operation device, then applies a sub-driving signal to the coil to adjust an attenuation period of the vibration. The sub-driving signal has a variable voltage varying with an offset voltage, as a center value, offset from a zero voltage, and a waveform that indicates a variation in the variable voltage is a sine function curve or a cosine function curve. The circuit applies the sub-driving signal while changing the offset voltage for each cycle.