Linear Motor Bandwidth Measurement via Indirect Displacement
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Solution Overview
Problem
Measuring the bandwidth of a linear motor is challenging due to heating issues that cause parameter deviations, packaging of the vibrator making direct displacement measurement impossible, and large amplitude non-resonant frequency signals exceeding allowable displacement limits.
Innovation Solution
A method that indirectly measures dynamic displacement using a calculation relationship between displacement and acceleration in a steady state vibration, segmenting the frequency band to prevent heating, and using a constant envelope sinusoidal signal to eliminate overshoot, allowing for accurate determination of the bandwidth by obtaining a frequency response curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long-time signal excites the linear motor to measure bandwidth, then the frequency response can be obtained, but the linear motor heats up causing parameters to change and deviate from linear working area
Solution Approach 1:
The patent applies periodic action by using a chirp signal that sweeps through the frequency range in a controlled periodic manner, allowing measurement of bandwidth without continuous long-time excitation that would cause overheating. The frequency response is obtained through this time-limited periodic excitation.
Solution Approach 2:
The patent uses preliminary action by pre-calculating the impulse response through Fourier transform of the chirp signal response, then using this pre-obtained impulse response to determine bandwidth characteristics without needing to apply continuous excitation signals.
2Reliability
If the vibrator is packaged in an outer housing, then the linear motor is protected, but dynamic displacement of the vibrator cannot be directly measured
Solution Approach 1:
The patent replaces direct mechanical displacement measurement with an indirect measurement method using acceleration sensors and mathematical transformation. The acceleration signal is integrated twice to obtain displacement, avoiding the need to access the packaged vibrator directly.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using acceleration as a mediator to infer displacement. Instead of measuring displacement directly, the system measures acceleration and uses signal processing (double integration) to derive displacement information from the packaged vibrator.
3Measurement precision
If a large amplitude non-resonant frequency signal excites the linear motor, then the frequency response can be obtained, but the displacement peak at initial phase exceeds allowable ultimate displacement
Solution Approach 1:
The patent uses periodic chirp signal excitation that gradually sweeps through frequencies, allowing the system to reach steady-state response at each frequency point without large initial transients that would exceed displacement limits.
Solution Approach 2:
The patent applies preliminary action by using frequency domain analysis (Fourier transform) to extract the frequency response characteristics from the impulse response, avoiding the need to apply large amplitude signals that would cause excessive initial displacement peaks.
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 accurate measurement of the linear motor's bandwidth by preventing parameter deviations and overshoot, ensuring the frequency response model remains linear, and facilitating precise touch feedback design in electronic devices.
Implementation Method 1
A linear motor is a core device which provides a touch feedback function
Implementation Method 2
an accelerometer is triggered to measure an acceleration output of the linear motor
Implementation Method 3
a transformation relationship between the displacement and the acceleration in a steady state vibration is determined; and the dynamic displacement corresponding to the large non-resonant frequency input signals is obtained by eliminating overshoot
Data Source
AI summary
The present disclosure provides a method for measuring bandwidth of linear motor, including the following steps: step S1: setting a frequency distribution of an excitation signal; step S2: with reference to a target displacement level, measuring a steady state displacement peak of a motor vibrator at each frequency point of the excitation signal, and obtaining a frequency response curve with reference to the target displacement level; step S3: according to the frequency response curve obtained in step S2, determining an upper frequency limit and a lower frequency limit with reference to the target displacement level, and obtaining a bandwidth of the linear motor by calculating a difference between the upper frequency limit and the lower frequency limit.