Development of a three degree-of-freedom testbed for an unmanned helicopter and attitude control design

To provide a safe and efficient test for the autonomous control design of the unmanned helicopter, a 3 degree-of-freedom (DOF) helicopter testbed is developed in this paper. The testbed uses a small electric hobby helicopter as the main body, a digital signal processsor (DSP) is employed as the on-board micro control unit (MCU) for the attitude control of the helicopter, a micro attitude and heading reference system (AHRS) is utilized as the main on-board sensor for attitude states feedback and a Bluetooth module is mounted on the testbed to provide realtime wireless communication between the helicopter and the ground control station (GCS). This paper investigates the servo actuators coordinated control method with separate channel of the new-style electric helicopter, which is named as electronic collective-cyclic pitch mixing (ECCPM). A modified digital incremental PID control algorithm which is free of servo actuators saturation issue is proposed for the attitude control of the helicopter. Finally, experiment results are provided to verify the testbed and control design.