Research On Heading And Attitude Sensor For Underwater Small Vehicle

Underwater vehicle(UV)positioning,especially in the civil field,mainly relies on the acoustic positioning system known as "underwater satellite navigation system".However,acoustic positioning system lacks the heading and attitude information used for navigation.In recent years,with the rapid development of small UV the free-calibration Ultra Short Base Line(USBL)Position System has increasingly become the main form of acoustic positioning system,which has an urgent need of the heading and attitude sensors(HAS)with small size,low power consumption and high precision.Aiming at the above requirements and problems,this paper designs a HAS based on MEMS inertial devices and magnetic sensors.This system adopts the high-performance 32-bit microcontrollers STM32F411RET6 as the core processing unit and the triaxial MEMS accelerometer,triaxial MEMS gyroscope and triaxial micro magnetic sensor as the sensing unit of carrier's motion information.Based on the embedded real-time operating system,?C/OS-?,the data processing software was developed to realize the scheduling and management of task such as data acquisition,fusion arithmetic and data communication,which can improve the real-time performance and stability of HAS.From the aspects of key performance indexes like power consumption and size,the sensor model is selected,and then the measurement precision of the sensor is improved through random error compensation and parameter calibration.Considering the complex temperature environment such as the deep sea,the temperature compensation model of the sensor on the basis of analyzing the temperature characteristics of the sensor was constructed.The model parameters are obtained from the high and low temperature experimental data by the least square method,modify the sensors change with temperature of the bias and sensitivity coefficient in real time and on-line to enhance the adaptability of the system environment temperature.In addition,in order to improve the stability and reliability of HAS,the Adaptive Unscented Kalman Filter(AUKF)algorithm is used to carry out data fusion after error compensation.The test results show that the power consumption of the heading and attitude sensor designed in this paper is about 0.125mW,which is about 27%of Ellipse2-A(SBG,France).In temperature range of-30??50?,the static measurement error of heading reduce to ±0.3° from ±0.85° after temperature compensation and AUKF data fusion.