The Analysis And Design Of High-precision Accelerometer Measurement System

Inertial navigation system is the autonomous track recurrence navigation system which uses inertial sensing device, the direction and the initial reference position and velocity information to determine the position and velocity of vector. Inertial system is autonomous, covert, real-time, weather, so it is widely used in a variety of navigation, guidance, position and stability control. Accelerometer is an important device for field of inertial navigation, which provides the fundamental basis for positioning and dead reckoning the velocity, as it is available to sense and detect the acceleration of vehicles. Accelerometer's output is proportional to the signal of vehicles'acceleration, and the output precision affect directly the precision of the inertial navigation system. And the high-precision Silicon Flexure Accelerometer commonly output an analog current signal. I/F converter circuit will change the analog current signal into a digital signal, and the converted accuracy should be higher than the accelerometer's original precision.Because the importance of accelerometer in the INS, and increasing of the accuracy of the accelerometer. The collection of the accelerometer's output signal is very important, it directly impact on the accuracy of inertial navigation system and it may be a waste of precision index accelerometer. In the accelerometer output signal acquisition system, digital output analog signal is a top priority. There are three methods for digital output analog signal. They are A/D conversion and current-voltage-frequency transformation and current-frequency transformation. A/D conversion and current-voltage-frequency transformation can not be very accurate. On this basis, after comparing of several current-frequency transformation methods, the project intends to design a high-precision measurement system for accelerometer. Propose pulse-width modulated binary feedback current integral mold conversion of the I/F transform the digital output accelerometer program, and show the system block diagram and the function of every part.Based on the system overall design, design each part of the circuit. Based on the relevant content of analog circuits and digital circuits, select chips and calculate parameters. Simulate the preliminary designed circuit with the NI Multisim circuit simulation software, and further determine the functions and parameters of each part of the circuit. Debug after designed and product the PCB, and proof system can achieve the function of current frequency conversion.Finally, compare the kinds of method for collecting. Taking into account the accuracy and difficulty of collection method, propose the method with the multi-period synchronous, and show the block diagram. Gave the recommendation for the system's improvement.