Machine Design

PEEPING SUBMARINE: Brush motors get commands from a smartphone

Aquabotix Technology Corp.

maxon precision motors inc.

An underwater remotely operated vehicle using an Android-based smartphone or iPad as a controller lets those on the surface garner close-up views of life under the sea. The HydroView, from Aquabotix Technology Corp., Fall River, Mass., provides a way of capturing photos or live videos that stream to a PC, an iPad, or an Android-based smartphone.

The HydroView weighs less than 10 lb. The unit’s topside box uses localized Wi-Fi technology that communicates wirelessly with the operator’s handheld device. The box connects to the submersible via a cable tether. A bank of LED lights surrounds an HD camera that streams video to the operator so he or she can see exactly where to maneuver the submersible. Ease-of-use was foremost in the design. Operating the submersible is like playing a video game, giving the vehicle’s controls a familiar feel. The sub operates on 10 Vdc from a battery, which can supply power for up to 3 hr depending on how it is used. Users can study sea life, search for lost objects, or explore shorelines. Commercial uses might include checking live bait cages or aiding in taking a boat out of the water.

The sub is powered by three propellers, one on either side and one at the rear. Each is run by a brush-dc A-max motor designed and manufactured by maxon precision motors inc., Fall River, Mass. The A-max motor was chosen because it generates high torque in a 26-mm package. Torque is more important than speed when designing for underwater use because of water’s inertia against the propellers.

However, smooth, low-vibration operation was even more important than high torque. The motors are sealed for work underwater, so any vibration in the motor shaft could cause leaks, damaging the motors, control board, and camera. And the long shafts needed on the motors would amplify any vibrations, making the problem worse. Making the long shafts part of the motors minimizes additional vibrations.

The vehicle maneuvers through the water using the speed-controlled side motors. Right and left movements are made by adjusting left and right motor speeds. The third motor in the tail controls vehicle pitch.

Forward motion maxes out at about 5 knots, and the sub is rated for depths down to 150 ft. The side propellers have reversed pitches, so the motors run in opposite directions. This eliminates any twisting torque from the motors and helps stabilize the vehicle in the water.

The on-board controller runs under Linux and can be programmed in a variety of languages, including C and C++. The iPad version uses the Cocoa environment while the Android and PC versions can be programmed using Java.

Because the sub is controlled like a video game, almost anyone can begin using it fairly quickly. Movement translated through a user’s control panel using gestures or accelerometers simplifies operation.

The HydroView is 14.6-in. wide, 19-in. long, and 7-in. tall and comes in safety orange and black. Options include a 300-ft cable, hovering control software, extended battery operation, and deluxe pontoon lights.

© 2012 Penton Media, Inc.

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