Machine Design

Rotary actuators keep a level playing field

Oriental Motor USA

Camera operators roaming the sidelines of football games televised on ESPN these days have an easier time keeping up with the action on the field thanks to the clever combination of rotary actuators, a digital bubble level, and automated TV cameras. Working with automation specialist Kiser Controls Co. in Burr Ridge, Ill., the Fletcher Chicago Sports Div. of Fletcher Camera & Lenses, Chicago, devised a camera that can level itself as it moves along the sidelines. This is important because football fields typically aren’t perfectly flat; they can tilt by several degrees from one end zone to the other.

Cameras sit on an electric cart that a camera operator steers along the sidelines. There are two cameras on the platform (to provide 3D picture transmissions if need be) mounted atop a column about 20-ft high. The camera platform attaches to a combination of two rotary actuators, one for the X direction, the other for Y. These actuators, from Oriental Motor USA in Torrance, Calif., have a hollow output table that lets wires and camera cables pass through. They employ precision gears along with a proprietary adjustment mechanism that eliminates backlash. The repetitive positioning accuracy in a single direction is ±15 sec, while accuracy in a positioning operation from two directions is 2 arc-min.

Completing the system is a digital inclinometer that monitors camera tilt and sends that information back to a positioning controller. In operation, the camera operator sitting on the platform watches the TV view. If necessary, he or she hits a button that tells the controller to level the 200-lb camera platform.

© 2013 Penton Media, Inc.

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