Research On High-precision Motion Acceleration Measurement System

Maneuvering performance is one of the most important performances of underwater vehicle. In the implementation of some special missions, the underwater vehicle needs to control depth and pitch attitude in parking state, which is known as the underwater vehicle hovering control. Good hovering performance can reduce the noises of the underwater vehicle, improve the concealment, reduce the power consumption, and enhance the ability to maneuver, which is of strategic significance. Measurement of underwater vehicle acceleration can provide important information for the vehicle hovering control, which can be more effective and more accurately to realize the underwater hovering automatic control. However, there are a lot of research work needs to be done to realize underwater vehicle hovering control by the measurement of vehicle acceleration.Existing wide range acceleration measurement system can’t meet the requirements of high accuracy applications. This thesis studies the wide range and high-precision motion acceleration measurement system based on quartz flexible accelerometer. The main contributions include the following aspects:1. A method for improving the accuracy has been proposed based on the analysis of the error sources of quartz-flex accelerometer. It includes a novel design of electromagnetic shielding for the accelerometer and a precise solution of temperature controlling.2. According to the measurement requirement of weak current signal output by the accelerometer, a design of high-accuracy current measurement has been investigated. The analog part of the circuit for high-accuracy current measurement is based on the AD conversion to convert the analog signal to digital signal. Noise suppression technology and double-channel fusion technology have been implemented to efficiently improve the signal-to-noise ratio of the measurement circuit. Moreover, a special structure for constant temperature controlling has been designed for the analog part of circuit.3. According to the requirements of the high-accuracy measurement of acceleration for underwater vehicle hovering control, a special acceleration decoding algorithm with the separation of gravity has been investigated. And this thesis presents a method of using three-axis acceleration to correct gyroscope drift error.Finally, plenty of experiments have been taken to study the high-accuracy measurement system for the motion acceleration. The experimental results demonstrated that the technical specifications of the acceleration measurement system had reached the expected target.