Embedded implementation of a nonlinear-observer-based AHRS

Abstract

This paper deals with the implementation of a nonlinear observer to estimate the attitude of a rigid body from the measurements of MARG (Magnetic, Angular Rate, and Gravity) low-cost sensors. As a consequence, the system developed enters into the more general framework of Attitude Heading Reference Systems (AHRS). Thus, a quaternion-based nonlinear observer together with the use of Kaczmarz's method is proposed to fuse the sensor signals. The stability analysis for the attitude error dynamics is carried out using the ISS (Input-to-State Stability) framework. In this sense, the proposed observer is robust stable, when the measurement disturbance is seen as an input and the error as the state. The attitude estimation strategy is very simple to implement and is computationally light, which allows is to be easily deployed across various hardware-software platforms. Particularly, in this work, the algorithm is programmed in the Solidthinking Embed ® software and downloaded in a 32-bit microcontroller Piccolo F28069M, for its use in real-time. Experiments are carried out using a high accuracy system as reference and then comparing with the estimated attitude in order to demonstrate the observer performance.