Helicopters have been used in applications where they need to carry a slung load for years. More recently, unmanned (UAV) helicopters are being used to deliver supplies to military units on the ground in theaters of war. This thesis presents a helicopter slung vehicle used to carry the payload and furthermore, provide a means of actuation for the payload. This provides more control authority to the system and may ultimately allow a helicopter to fly higher with a longer tether. The vehicle designed in this thesis was designed for use with 100kg class helicopters, such as the Yamaha RMAX operated by the Virginia Tech Unmanned Systems Lab. Each system on the vehicle was custom designed — including the propulsion system, wall detection / localization system, and controller. Three shrouded propellers provided thruster actuation. A scanning laser range finder and inertial measurement unit (IMU) were used to provide localization. A first attempt at a linear full state feedback controller with a complementary filter was used to control the vehicle. All of the systems were tested individually for functionality. The shrouded propellers met their design goals and were capable of producing .7lbf of thrust each. The wall detection system was able to detect walls and windows reliably and with repeatability. Results from the controller however were less than ideal, as it was only able to control yaw in an oscillatory motion, most likely due to model deficiencies. A reaction wheel was used to control yaw of the vehicle with more success. / Master of Science

The use of small scale Unmanned Aerial Vehicles (UAVs) is quickly becomingcommonplace in many domains. Operating such vehicles often requires using aspecialized radio control (RC) transmitter. One objective of this thesis is toinvestigate the use of other means of controlling a particular type of a UAV - aquadrotor. Two types of alternative devices are investigated, a standard gamingconsole controller PlayStation 3 gamepad (PS3 gamepad) and a smartphone(Android OS based). The purpose of substituting the RC controller is to make iteasier for a novice user to operate a UAV. The second objective is to investigate solutions to the problem of slung load control. A slung load is a uniform mass attached to a platform with a wire that may swingfreely. The slung load control problem consists of several subproblems: slung loadmodeling, altitude control, filtering of sensor data and the slung load control itself. The purpose of controlling the slung load is to reduce the oscillations of the load inflight and to minimize its influence on the flight performance of a UAV. Both types of alternative interfaces to the UAV were designed and implemented. Inorder to interface with the quadrotor platform at hand a new communicationprotocol based on TCP/IP was introduced. A study of the design process and typicaluse cases was performed. The two types of interfaces were evaluated by a group oftarget users as well as in real flight tests. The game controller was easy to use whilethe smartphone interface required automatic altitude control to be really useful. The evaluators found that the smartphone provided a smoother control over the steeringcompared to using the joystick on a game controller. The slung load control problem was investigated theoretically and in practice on astationary testing rig. The altitude control problem has been addressed byincorporating a PID controller which uses filtered data from a pressure sensor. ThePID control was extended with an anti-windup mechanism combined with afeedforward control of the tilt angle. A mechanism for a smooth transition from themanual to automatic altitude control modes was implemented and verified in flighttests.

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