Low cost navigation system for UAV's

Abstract

This paper describes the development of a navigation system for SIVA family of UAVs that incorporates measurements from low cost solid state IMU and magneto-resistive magnetometer, single receiver inexpensive GPS, and absolute and differential pressure transducers. The navigator is composed of three modules: an attitude estimator, a position and velocity estimator and a mission management module. All the UAV navigation, guidance, control and communication algorithms and processes run on a PC-104 Pentium I processor. The attitude estimator algorithm is a computationally-inexpensive nonlinear observer developed using Lyapunov theory that computes angular velocity corrections from two vector measurements: Earth's magnetic field and gravity, guaranteeing global Input to State Stability. The position and velocity estimator consists of a set of three static linear Kalman filters that correct the integration of local level components of acceleration with GPS, pressure derived altitude and airspeed measurements. The autonomous navigation is performed by means of pre-programmed mission data, composed by a set of mission elements which define the trajectory to guide the UAV through a safe path. Mission data, mission phases and ground control modes are managed by the mission management module.