Bias and misalignment compensation for 6-dof imu using gnss/ins data

Abstract

A system and method for correcting bias and angle misalignment errors in the angle rate and acceleration outputs from a 6-DOF IMU mounted to a vehicle. The method includes providing velocity and estimation attitude data in an inertial frame from, for example, a GNSS / INS, and determining an ideal acceleration estimation and an ideal rate estimation in a vehicle frame using the velocity and attitude data. The method then determines the IMU bias error and misalignment error using the ideal acceleration and rate estimations and the angle rate and acceleration outputs in an IMU body frame from the IMU.

Description

BACKGROUND OF THE INVENTION[0001]Field of the Invention[0002]This invention relates generally to system and method for determining bias and misalignment errors in the outputs from a 6-degree of freedom (DOF) inertial measurement unit (IMU) and, more particularly, to a system and method for determining bias and misalignment errors in the outputs from a 6-DOF IMU on a vehicle using velocity and attitude data from a global navigation satellite system (GNSS) and / or an inertial navigation system (INS), where the method includes determining an ideal acceleration estimation and an ideal angle rate estimation in a vehicle frame using the velocity and attitude data, and determining an IMU bias error and a misalignment error using the ideal acceleration and angular rate estimation and the measured angle rate and acceleration outputs from the IMU.[0003]Discussion of the Related Art[0004]The operation of modern vehicles is becoming more autonomous, i.e., vehicles are able to provide driving con...

AI Technical Summary

Benefits of technology

The present invention is a system and method for correcting bias and angle misalignment errors in the angle rate and acceleration outputs from a 6-DOF IMU mounted to a vehicle. The method involves providing accurate velocity and estimation attitude data in an inertial frame from, for example, a GNSS / INS, and determining an ideal acceleration estimation and an ideal rate estimation in a vehicle frame using the velocity and attitude data. The method then determines the IMU bias error and misalignment error using the ideal acceleration and rate estimations and the angle rate and acceleration outputs in an IMU body frame from the IMU. The technical effect of this invention is to provide accurate and reliable data for vehicle navigation and control.

Problems solved by technology

However, sometimes sensors and control modules that determine vehicle speed fail or operate improperly, where loss of vehicle speed could be serious.

However, the measurements of acceleration and angular rates provided by the IMU on a vehicle for this purpose usually deviate from the actual acceleration and angular rate values due to several error sources.

The two major sources of error for the IMU measurements are accelerometer and gyro bias components and frame misalignment corresponding to mounting the IMU to the vehicle.

Although it is desirable to perfectly align the IMU with the vehicle frame, there still are mounting errors that even if they are small, could provide significant misalignment errors in the calculations.

However, such error corrections of bias and misalignment are also difficult to accurately obtain.

Further, these error corrections for bias and misalignment often require special vehicle maneuvers during the manufacturing stage of the vehicle, and further bias terms are not fixed and may change in time due to different road, vehicle and environment conditions.

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