Implementation of an Obstacle Avoidance Controller on the OS4 Mini-Helicopter

Abstract

3 EPFL - CH 1015 - Lausanne, Switzerland Abstract: OS4 (Omnidirectional Stationary Flying OUtstretched Robot) is an electrically powered four-rotor miniature helicopter developed towards fully autonomous operation in indoor/outdoor environments. The major goal of this research is the development and implementation of an active control system for a quadrotor helicopter. However, one has to consider seriously the design aspect in order to get rid of the hardware limitations and achieve control simplification. Controlling a VTOL (Vertical Taking-Off and Landing) flying robot is basically dealing with highly unstable dynamics and strong axes coupling. In addition to this, any additional on-board sensor increases the robot total weight and therefore decreases its operation time. It is necessary to find a balance between on-board electronics and robot operation time. This paper focuses the development and implementation of an obstacle avoidance controller for this miniature flying robot using four ultra-sound (US) sensors for detecting obstacles and one US sensor for controlling its altitude. In order to facilitate the controller implementation, we developed a simulation tool in Matlab/Simulink using an accurate dynamic model of OS4. This tool allowed us to simulate and improve the OS4 controllers in different modeled environments and applying different approaches. The controller real implementation was carried out for hovering state and the results were encouraging.