Abstract
This paper presents an improved iterative nonlinear calibration method in the gravitational field for both low-grade and high-grade triaxial accelerometers. This calibration method assumes the probability density function of a Gaussian distribution for the raw outputs of triaxial accelerometers. A nonlinear criterion function is derived as the maximum likelihood estimation for the calibration parameters and inclination vectors, which is solved by the iterative estimation. First, the calibration parameters, including the scale factors, misalignments, biases and squared coefficients are estimated by the linear least squares method according to the multi-position raw outputs of triaxial accelerometers and the initial inclination vectors. Second, the sequence quadric program method is utilized to solve the nonlinear constrained optimization to update the inclination vectors according to the estimated calibration parameters and raw outputs of the triaxial accelerometers. The initial inclination vectors are supplied by normalizing raw outputs of triaxial accelerometers at different positions without any a priori knowledge. To overcome the imperfections of models, the optimal observation scheme is designed according to some maximum sensitivity principle. Simulation and experiments show good estimation accuracy for calibration parameters and inclination vectors.
Highlights
Triaxial accelerometers have been used extensively in the fields of inertial navigation and gravimetry [1,2]
In view of the above disadvantages, this paper proposes an improved iterative calibration method for both linear and nonlinear models of triaxial accelerometers
To verify the measurement accuracy of triaxial accelerometers in the total gravity space, the positions for estimation and additional 48 positions for verification are respectively described in Figure 5(b) and the estimation and verification errors are shown in Laboratory calibration of triaxial accelerometers is a necessary step for high-accuracy specific force measurements
Summary
Triaxial accelerometers have been used extensively in the fields of inertial navigation and gravimetry [1,2]. A promising multi-position calibration for triaxial accelerometers in the gravitational field has been proposed as an effective solution to relax the precise orientation supplied by the setup [3,4,5,6,7,8,9,10,11,12,13,14]. In view of the above disadvantages, this paper proposes an improved iterative calibration method for both linear and nonlinear models of triaxial accelerometers. A maximum sensitivity of some constant output as a function of calibration parameters is designed to make the measurement accuracy of triaxial accelerometers consistent in the whole gravitational field.
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