Optical Linear Encoder Feedback for Vibration Exciter Precision
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Solution Overview
Problem
Vibration sensors face challenges in ultralow frequency measurement and calibration due to low precision and friction issues with traditional displacement sensors, which affect the accuracy of vibration exciters in applications like aeronautics and ultra-precision manufacturing.
Innovation Solution
A vibration exciter system with a feedback control unit based on an optical linear encoder, which converts displacement into high-precision A/B pulses, processes them through wave filtering and shaping, and uses a PID controller to drive the exciter, ensuring non-contact measurement and minimizing harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional displacement sensors are used for feedback control, then the exciter can operate at low frequencies, but the measurement precision is low and friction affects the moving component
Solution Approach 1:
The patent replaces traditional mechanical contact-type displacement sensors with a non-contact optical linear encoder system. The optical encoder uses light to detect displacement without physical contact, thereby eliminating friction on the moving component while providing high-precision measurement. The encoder consists of a scale grating and a detection head that reads position optically, substituting the mechanical contact measurement mechanism with an optical field-based measurement approach.
2Measurement precision
If contact-type displacement sensors with high precision are used, then measurement precision improves, but friction and tension are caused to the moving component
Solution Approach 1:
The patent replaces mechanical contact measurement with optical non-contact measurement. The optical linear encoder uses a light source, scale grating, and photodetector array to measure displacement optically without any mechanical contact. This substitution eliminates the friction and tension forces that would otherwise be exerted on the moving component by contact-type sensors, while maintaining or improving measurement precision through optical interference or diffraction patterns.
3Speed
If conventional feedback control is used at low frequency, then the exciter operates in the required frequency range, but the signal-to-noise ratio is low and output signal amplitude is small
Solution Approach 1:
The patent implements a closed-loop feedback control system where the optical linear encoder continuously measures the actual displacement of the moving component and feeds this information back to the control system. The feedback signal is processed through a PID controller that compares the actual position with the desired position, generating error correction signals. This high-precision feedback mechanism enables the system to maintain accurate control at low frequencies where signal amplitudes are small, effectively improving the signal-to-noise ratio by using the precise optical measurement data to compensate for weak signals.
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 system significantly improves the precision and accuracy of the exciter's output waveform, particularly at low frequencies, by leveraging the high precision and non-contact measurement capabilities of optical linear encoders, addressing the limitations of traditional displacement sensors.
Implementation Method 1
an optical linear encoder converting the displacement of the moving component of exciter into A/B pulse with a phase difference of 90°
Data Source
AI summary
The vibration exciter system with a feedback control unit based on an optical linear encoder includes a vibration exciter, a signal generator and a power amplifier. The exciter system further comprises an optical linear encoder converting the displacement of moving component of the exciter into A/B pulse with a phase difference of 90° , a filtering, shaping and level translator unit converting the A/B pulse into standard pulse with standard shape and level, a subdivider and orientation recognizer unit refining standard pulse and recognizing the moving orientation, an analog converter unit converting refined standard pulse into analogue signal that reflects the displacement of the moving component. The standard signal outputted by the signal generator and the converted analogue signal are inputted into a subtracter as the minuend and subtrahend respectively. The output of the subtracter is inputted into the power amplifier and then into the vibration exciter as a driving signal.