Longitudinal Rate Gyro Bias and Pitch Attitude Estimation Utilizing an Accelerometer Array

In this paper, a novel attitude estimation device is proposed utilizing cost-efiective rate and acceleration measurement sensors. The device combines a rate gyroscope with an accelerometer array and algorithm to estimate and eliminate the rate gyro bias online for accurate real-time aircraft longitudinal attitude tracking. Proper vehicle operation is predicated on accurate attitude determination algorithms that are dependent on instantaneous and accurate measurements of translational and rotational body rates for precise estimation of vehicle orientation in three-dimensional space. Measurement error of instantaneous rate sensors, gyroscopes, is introduced via inherent biases and signal noise resulting in gyro drift. Integration of the rate signal for instantaneous net displacement calculation amplifles even minute measurement errors leading to an inaccurate and unreliable attitude estimate. The proposed device is a departure from typical attitude observers and bias estimators due to reliance on accelerometers measuring the local gravitational vector in lieu of additional magnetic fleld sensors or GPS. The end result is a longitudinal attitude estimation device able to compute a rate gyro bias in real-time for accurate vehicle pitch angle tracking while subjected to simulated aircraft ∞ight conditions. The efiectiveness of the newly constructed attitude estimation algorithm is demonstrated by comparison of attitude and rate gyro bias estimates produced from noise corrupted and biased sensors with the actual attitude of a nonlinear aircraft model and true rate gyro bias.