Electromechanical Transducer Frequency Tracking With Ring-Down Locking
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Solution Overview
Problem
Electromechanical systems face challenges in maintaining resonance frequency stability due to variations from fabrication tolerances, temperature, stress, humidity, and other ambient conditions, leading to electrical feedthrough and signal corruption in transducers and sensors.
Innovation Solution
An apparatus and method that lock the resonant frequency of an electromechanical subsystem by tuning the operating frequency of either the electrical or mechanical system to match the other, using a ring down period to determine the settling response and adjust the frequency accordingly, with mechanisms such as smart materials and bias voltage adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromechanical transducers are operated at resonance to increase motion and sensitivity, then the motion and sensitivity of the device are improved, but electrical feedthrough from the actuation signal to the sensor signal corrupts the sensor signal
Solution Approach 1:
The patent extracts and removes the harmful electrical feedthrough signal from the sensor output by subtracting a scaled version of the actuation signal from the sensor signal, isolating the true mechanical response from the electrical interference
Solution Approach 2:
The patent uses feedback by monitoring the sensor signal during actuation and using this information to adjust the scaling factor applied to the actuation signal, enabling dynamic cancellation of electrical feedthrough effects
2Adaptability or versatility
If the resonance frequency of the mechanical subsystem is allowed to drift independently due to fabrication tolerances and ambient conditions, then the system adapts to environmental changes, but frequency mismatch occurs between the electrical and mechanical subsystems
Solution Approach 1:
The patent implements a feedback mechanism where the measured resonance frequency from the sensor signal is used to adjust the actuation frequency, creating a closed-loop system that maintains frequency synchronization despite environmental variations
Solution Approach 2:
The patent makes the actuation frequency dynamic by allowing it to be adjusted in real-time based on the measured resonance frequency, transitioning from a fixed frequency system to an adaptive frequency-tracking system
3Reliability
If the operating frequency is tuned to match between electrical and mechanical systems, then frequency stability is improved, but additional frequency tuning mechanisms and control circuits are required
Solution Approach 1:
The patent enables the system to self-tune by using its own sensor output to determine the resonance frequency and automatically adjusting the actuation frequency without requiring external tuning equipment or complex manual calibration procedures
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
This approach stabilizes the resonant frequency, reducing frequency mismatch and signal corruption, enabling accurate object detection and tracking in applications like ultrasonic gesture recognition with improved sensitivity and range.
Implementation Method 1
Mechanical systems (and subsystems) typically have one or more resonant frequencies arising from various vibrational modes of the system. Electromechanical actuators may be configured to operate at or near resonance in order to increase the motion of the device, and mechanical sensors may also be operated at resonance to increase the sensitivity of the device.
Implementation Method 2
During the ring down period, a ring down circuit is activated which attenuates resonance of the electromechanical subsystem in a controlled manner allowing settling response to be readily determined.
Data Source
AI summary
An apparatus and method for frequency tuning/tracking between an electrical subsystem and a mechanical transducer subsystem is presented. An electromechanical transducer generates acoustic pulses as it is driven by a transmit signal from an electrical subsystem. As the transmit signal goes inactive, the settling behavior of the transducer is registered from which the difference in frequency between the resonance of the electromechanical transducer and the transmit signal frequency is determined and utilized for locking the electrical subsystem to the mechanical transducer subsystem by either tuning operating frequency of the electrical subsystem, or the mechanical transducer, to keep them matched (locked).