Fly-the-Camera Perspective: Control of a Remotely Operated Quadrotor UAV and Camera Unit

This Chapter presents a mission-centric approach to controlling the optical axis of a video camera mounted on a camera positioner and fixed to a quadrotor remotely operated vehicle. The approach considers that for video collection tasks a single operator should be able to operate the system by ”flying-the-camera”; that is, collect video data from the perspective that the operator is looking out of and is the pilot of the camera. This will allow the control of the quadrotor and the camera manipulator to be fused into single robot manipulator control problem where the camera is positioned using the four degree-of-freedom (DOF) quadrotor and the two DOF camera positioner to provide a full six DOF actuation of the camera view. Design of a closed-loop controller to implement this approach is demonstrated using a Lyapunov-type analysis. Computer simulation results are provided to demonstrate the suggested controller. Historically, the primary driver for UAV reconnaissance capabilities has been military applications; however, we appear to be at the juncture where the cost and capabilities of such systems has become attractive in civilian applications. The success of recent UAV systems has raised expectations for an increased rate of technology development in critical factors such as low-cost, reliable sensors, air-frame construction, more robust and lightweight material, higher energy-density battery technologies, and interfaces that require less operator training. One of the essential technologies is the camera positioner, which includes camera, camera base, and multi-axis servo platform. The potential for UAVs with camera positioners has been well established in many applications as diverse as fire fighting, emergency response, military and civilian surveillance, crop monitoring, and geographical registration. Many research and commercial groups have provided convincing demonstrations of the utility of UAVs in these applications. Most of the commercial systems are equipped with camera positioners as standard equipment; however, the use of the camera is not integrated with the control of the UAV. The typical structures of a camera positioner include pan-tilt, tilt-roll, or pan/tilt/roll revolute joints or multi-axis gimbals. When considering the actuator of the camera gimbal, rate-gyros or encoders are used to measure the orientations. If the system is small and lightweight, the actuator dynamics can be discounted or neglected in the control of the UAV. Heavier systems, relative to the UAV, may require that the interaction of the camera