Abstract
Inertial navigation system (INS) measures vehicle’s angular rate and acceleration by orthogonally mounted tri-axis gyroscopes and accelerometers and then calculates the vehicle’s real-time attitude, velocity, and position. Gyroscope drifts and accelerometer biases are the key factors that affect the navigation accuracy. Theoretical analysis and experimental results show that the influence of gyroscope drifts and accelerometer biases can be restrained greatly in rotation INS (RINS) by driving the inertial measurement unit (IMU) rotating regularly, thus improving navigation accuracy significantly. High accuracy in position and velocity should be matched with that in attitude theoretically since INS is based on dead reckoning. However, the marine and vehicle experiments show that short-term attitude output accuracy of RINS is even worse compared with that of nonrotation INS. The loss of attitude accuracy has serious impacts on many task systems where high attitude accuracy is required. This paper researched the principle of attitude output accuracy loss in RINS and then proposed a new attitude output accuracy improvement algorithm for RINS. Experiment results show that the proposed attitude compensation method can improve short-term pitch and roll output accuracy from 20~30 arc seconds to less than 5 arc seconds and azimuth output accuracy improved from 2~3 arc minutes to less than 0.5 arc minutes in RINS.
Highlights
Inertial navigation systems (INS) employ inertial sensors to establish an inertial platform for measuring vehicle’s angular rate and acceleration and calculate vehicle’s attitude, velocity, and position based on dead reckoning principle
With the development of technology, inertial platform INS is replaced by strapdown INS gradually, in which the inertial sensors are fixed along body axes and the physical platform is constructed mathematically by the attitude transformation matrix
Strapdown configurations could reduce system cost and increase system reliability greatly compared with physical platform INS, while, in both physical platform system and strapdown system, position errors accumulate with time because of gyroscope drifts and accelerometer biases
Summary
Inertial navigation systems (INS) employ inertial sensors (gyroscopes and accelerometers) to establish an inertial platform for measuring vehicle’s angular rate and acceleration and calculate vehicle’s attitude, velocity, and position based on dead reckoning principle. The tri-axis RINS system is designed with three-axis continuous rotation scheme [13] and can compensate the scale factor error of sensors, installation axis instability, gyroscope drifts, and so forth. These papers demonstrate that RINS has been widely researched and has huge prospect for improving INS navigation accuracy. This paper researched the reasons that caused the loss of RINS attitude output accuracy and presented the corresponding attitude accuracy improvement algorithm.
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