A New Calculative Method for Gyro-Free Inertial Navigation System Using 9Accelerometers

Errors of gyro free inertial navigation system(GF-INS) using 6 accelerometers grow faster with time comparing with the conventional inertial navigation system(INS),for the reason that it has one more integral operation when calculating the angular velocity.To improve the accuracy of GF-INS,a novel scheme of 9 accelerometers GF-INS is proposed and a new calculative method is discussed,which can eliminate the iterative errors of integral operation for angular velocity calculation and calculate linear acceleration with the difference of outputs of accelerometers only.So the constant biases of Accelerometers and coupling errors from angular movement can been eliminated.This scheme can calculate squares of angular velocity,angular accelerations and linear accelerations with only the linear combination of outputs of 9 Accelerometers,so the computation is very simple and timesaving.This schome regards three-dimensional squares of angular velocity,angular accelerations and linear acclerations as 9 independent variables,so the 9 accelerometers GF-INS has the least accelerometers.The simulation results show that the divergence of errors is restrained remarkably with the new calculative method.