A Small Scale Rotor UAV Autonomous Flight Control System Design and Verification

Abstract

This paper present a small scale rotor UAV system design and verification through actual flight test. The rotorcraft is chosen as a base platform for UAV system because it offers unique characteristics such as vertical take-off and landing, hovering capability and maneuverability suited to various mission objectives. By using a powerful computer, navigation sensors and communication modem an onboard control system is developed. The flight tests have been conducted to demonstrate the designed flight control system. Furthermore, autonomous take-off and landing are successfully achieved by using the rotor UAV system. I. Introduction n general, rotor UAV(RUAV)s are represented by unique characteristics such as vertical take-off and landing(VTOL) without a runway support as well as hovering capability suited to various mission objectives such as surveillance, infrastructure inspection, mine detection, search and rescue and so on. Such unique advantages have been main impetus for intensive research activities on RUAVs. With recent technological advances in UAV systems design, the RUAVs began to be used as a testbed to explore various levels of emerging technologies such as autonomous flight, collision avoidance, path planning, obstacle avoidance, and image-based landing. There are many other potential applications and demonstrations possible by RUAV systems. 1-3 In general, the design of flight control system for helicopters is a difficult problem because of inter-axis coupling, unstable dynamics and non-minimum phase dynamic characteristics. 5 The vertical take-off and landing controller is needed to utilize RUAV’s maneuverability. The reliable avionic system is required due to large engine vibration and unstable dynamics of RUAV. There are many difficult factors to realize RUAV system. In this study, a small scale RUAV system design and verification through actual flight test are presented. The RUAV is equipped with self-developed autopilot system. The autonomous flight control system enables preprogrammed way-point navigation with navigation accuracy about 1m. Autonomous take-off and landing using highly precise onboard global positioning system (GPS) was demonstrated many times with consistent landing accuracy 0.5m. A salient feature of the RUAV system is in ground control system (GCS), which provides remote command, realtime telemetry, flight mode selection and various in-flight gain tuning capabilities and contingency management function. This paper is organized as follows. Section II describes the RUAV platform, avionics and software structure. Section III shows the autopilot design, implementation and flight control modes. Section IV presents our experimental results and flight test experience. Section V gives conclusion.