A Numerical Study of Low-cost Wind Velocity Estimation using Extended Kalman Filter and Tethered, Spherical Helium Balloon

Abstract

The objective of this work is to investigate the feasibility of low-cost wind-characterization using an inertial measurement unit (IMU) attached on a helium balloon. The balloon system acts as a measuring instrument for wind characterization. The wind velocity and direction are to be determined using only a standard set of on-board sensors (i.e., accelerometers, gyroscope, thermometer, and barometer). An Extended Kalman Filter (EKF) technique is implemented with the formulation of equations of motion describing the dynamics for the spherical balloon configurations (i.e., slung motion and free motion). The ability of the system to capture both a low frequency component and a turbulence component (i.e., high frequency variations) is determined. The effects of design parameters (such as balloon size and sensing errors) are investigated and analyzed with the use of numerical simulations. The feasibility of low-cost wind-characterization is found for the wind with a frequency lower than 0.05 Hz. It is found that the limitation is due to the error of gyroscope.