A Method to Estimate Surface Unevennes for Automatic UAV Landing

Delivering cargoes by unmanned aerial vehicles becomes an urgent task. To land a cargo accurately, drone should be able to choose an even landing site. For this aid it is suggested using ultrasonic altimeters. The paper presents the results of experimental research of ultrasonic signals backscattered by uneven surfaces and suggests a mathematical model for those signals. Methods for estimation of ultrasonic signal parameters (namely pulse duration and signal delay) and of surface roughness are developed.