Flight Control System Design For Miniature Rotorcraft UAV

Due to its outstanding maneuverability, relatively low cost and the ability totake off and land vertically, rotorcraft UAV has been chosen to conduct diversetasks including transportation, reconnaissance, search and rescue, among others.Most rotorcrafts are statically unstable aircraft and high performance flight controlsystems are necessary to make the most of their operating characteristics. This paperpresented the study on flight control system design for rotorcraft UAVs.Firstly, dynamic models of quadrotors and conventional helicopters wereestablished.Secondly, a low cost multi-sensor fusion AHRS solution is presented to takethe advantage of the flight characteristics of rotorcrafts. A discrete first order objectis applied as a low-pass filter to process the output of sensors. A MEMS gyroscopeis mounted in the system to measure the change in attitude of the UAV and theoutcome is corrected by an accelerometer and a magnetometer to eliminate gyrodrift. This solution could provide estimation on the UAV’s attitude and heading withlong term stability and acceptable precision.A dual-loop PID controller is derived basing on the information acquiredthrough the analysis of the rotorcraft dynamics. It computes control quantity fromthe output of AHRS and gyroscope and project the control quantity to servomechanisms to change the status of the UAV as expected.Finally, all the design was realized with hardware. Trail flights on quadrotorsand helicopters were conducted to proof that all the content of the paper isapplicable.Emphasis has been place on design of parameters in each part of the flightcontrol system. An applicable example of all the parameters concerned is included.