High Precision Rotation Sensor Using Load-Sensitive Resonators
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Solution Overview
Problem
Conventional seismometers and rotation sensors face challenges in accurately distinguishing between horizontal translation and ground rotation, particularly in measuring weak long-period vertical ground acceleration, and have limitations in sensitivity and dynamic range, especially when dealing with strong earthquakes.
Innovation Solution
A digital high precision rotation sensor using load-sensitive resonators that measure rotational inputs directly, with inertial masses suspended to generate torques and forces coupled to load-sensitive resonators, allowing for high-resolution, inherently digital measurements of rotational inputs and derived values of angular rate and rotation, employing mechanical overload stops and high-speed clocks for precise frequency measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional long-period seismometers with large inertial masses and soft springs are used, then sensitivity to weak long-period vertical ground acceleration is improved, but the full scale range is limited and the output is clipped if the earthquake is strong
Solution Approach 1:
The patent employs a dual-range measurement system where the sensor can dynamically switch between two measurement ranges. The first range uses a compliant support structure with soft springs for high sensitivity to weak accelerations, while the second range uses a rigid support structure for measuring strong accelerations without clipping. This dynamic reconfiguration allows the sensor to adapt to different earthquake intensities.
Solution Approach 2:
The patent divides the measurement system into two separate measurement paths: one for weak acceleration measurement and another for strong acceleration measurement. Each path has its own inertial mass, support structure, and readout system optimized for its specific range, allowing both weak and strong earthquakes to be measured accurately without compromise.
2Adaptability or versatility
If force-balance accelerometers are used, then acceleration full scale is improved, but sensitivity to weak long-period vertical ground acceleration deteriorates
Solution Approach 1:
The patent creates two specialized measurement systems: one optimized for weak acceleration detection using compliant supports and large inertial masses, and another optimized for strong acceleration measurement using rigid supports and force-balance technology. Each segment operates independently in its optimal range, avoiding the trade-off present in conventional single-range accelerometers.
3Ease of operation
If analog output sensors with analog-to-digital converters are used, then ease of operation is improved, but long-term stability and resolution deteriorate due to limited numeric dynamic range
Solution Approach 1:
The patent replaces the conventional analog-to-digital conversion chain with an optical measurement system. The position of the inertial mass is measured using optical interferometry or capacitive sensing, providing inherently digital, high-resolution output with excellent long-term stability. This eliminates the limitations of analog-to-digital converters while maintaining ease of operation through direct digital signal output.
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 high-resolution, broad-frequency-spectrum measurements of rotational inputs, overcoming the limitations of conventional sensors by providing enhanced sensitivity and dynamic range, distinguishing between horizontal acceleration and rotation, and improving long-term stability and accuracy.
Implementation Method 1
The load-sensitive resonators are set into their natural resonant frequencies by electronic means, and the resultant frequency output signals are measured with high-resolution frequency-period counters. The change in frequency of oscillation of the resonant force sensors is a measure of the applied force.
Implementation Method 2
A sensor is disclosed for providing high-resolution, inherently digital measurements of rotational inputs. The sensor includes an inertial mass that is suspended from a base such that rotational inputs generate torques and forces that are coupled to load-sensitive resonators
Data Source
AI summary
A high precision rotation sensor comprises an inertial mass suspended from a base wherein the mass is responsive to rotational inputs that apply loads to load-sensitive resonators whose changes in resonant frequency are related to the applied loads.