Flying over the action

Not to be confused with stationary, mounted cameras on top of buildings all over the country to monitor weather and traffic patterns, CF Inflight's Skycam is a robotic camera system that can dynamically view a sports field, arena, or concert stage from nearly anywhere and any angle within a defined space. The system has been used in football, basketball, and boxing broadcasts, as well as at the X-Games and Olympics, and it won an Emmy award for outstanding engineering achievement of 2002. At less than 30 lbs, the 36-in.-tall Skycam can "fly" at 28 mph from any point in a large, 3-D space to any other point to provide a unique view of a sporting or an entertainment event.

The Skycam system includes a camera assembly, a gyroscopic stabilization and camera-control system, a four-point cable-suspension system, fiber-optic video and data transmission, and a computerized controller that supports one or two operators. The camera assembly comprises a Panasonic AW-E800 camera that uses a 2/3-in. IT (Interline Transfer) Type 3 CCD system with a Fuji graphics-quality lens to deliver approximately 850 lines of resolution across an SDI (serial-digital-interface) output. The camera system also features 2-lux low-light sensitivity and a 65-dB SNR.

The spar is the structure that houses the Skycam's remote components, which ride the suspension-cable system (Figure 1). It allows the weight of the control electronics housed above the suspension system to neutrally match the weight of the camera assembly below the suspension system. Balancing the weight of the remote components above and below the suspension system allows the Skycam to use lightweight gyroscopic stabilizing mechanics to achieve more stable movement and a steadier image while moving.

The upper section of the spar houses the stabilization sensors, pan motor, power-distribution system, fiber-optic-communication components, and local processing boards for stabilizing and controlling the camera (see sidebar "Real-time control"). The lower section houses the camera, camera yoke, and tilt motor. Balanced at the spar's center of gravity is the reel system that forms the heart of the four-point cable-suspension and control system.

The Skycam's freedom of movement depends on four 0.1-in.-diameter, Kevlar-braided suspension cables, each with a tensile strength of 600 lbs. They connect the spar to four anchor points, such as the light stanchions in a stadium (Figure 2). Each suspension cable goes over a pulley and attaches to a spooling mechanism, known as a reel. The four reels work together to enable the Skycam to fly throughout the space within the four anchor points.

Commanding all of the reels to simultaneously pull in the cable raises the Skycam to a higher altitude. Likewise, commanding all of the reels to simultaneously release the cable lowers the system's altitude. Commanding two of the reels to pull in and the other two reels to let out simultaneously moves the Skycam laterally. A dedicated processor controls each reel. The central control computer instructs and coordinates the actions of the four reels and collects response and safety information through a fiber-optic network.

The Skycam uses single-mode fiber optics that run along each suspension cable to support higher resolution picture quality. This system also increases the data and communication reliability between the Skycam and the central control computer with redundancy by sending signals over all of the fiber-optic lines. Using fiber optics mitigates signal interruptions and avoids the distance and line-of-sight safety constraints that a wireless-transmission approach could necessitate.

The central control computer, in real time, monitors more than 80 sensor- and performance-based parameters, interprets the operator's joystick commands, tracks the Skycam's position, converts the operator's commands into positional coordinates, and synchronizes the action of each reel so that the Skycam performs the proper motion. The central control computer supports single- or dual-operator modes to control the Skycam motion and camera. If there are two operators, the second operator can focus on controlling the camera functions, such as pan, tilt, zoom, iris, and focus.

The central control computer allows the operators to focus on capturing the action by performing obstacle avoidance. Before deploying the Skycam, the operator describes any obstacles in the fly space. The operator abstracts the obstacles, such as a scoreboard, a column, goal posts, or fan seating, as primitive shapes and enters them into the Skypath software. The primitive shapes include planes, spheres, cones, boxes, cylinders, and four-point planes called curtains. When the Skycam is moving, the Skypath software prevents the camera and suspension lines from hitting any of the obstacles and, if possible, directs the Skycam around the obstacles.

The Skypath software can provide further assistance for the operators beyond obstacle avoidance. The operator can define custom reference points within the flight space to assist navigating and simplify common or repetitive actions. The software does not yet include image recognition and tracking to assist the operator in keeping the camera on the action, but it would not be surprising if such a feature became part of the system in the near future.

Author Information

You can reach Technical Editor Robert Cravotta at 1-661-296-5096, fax 1-661-296-1087, e-mail rcravotta@edn.com.