Robot Blimps
Learning to Fly
Dateline: 05/23/00
Building a walking or wheeled robot can be a daunting task. But no matter how successful your new project is, these "earthbound" robots will face serious challenges in the real world - even the smallest obstacles on the robot's way will probably make significant troubles, not to mention staircases and other notoriously difficult places for your mechanical companion. So, let's consider aerobots - flying robots - for your next project. It doesn't have to be cutting-edge, sophisticated micro-air robot like some of the projects described in one of the previous articles. However, model airplanes and helicopters are not well suited for such use, as they are rather difficult to control, noisy and dangerous - you don't want to see rotating propellers nowhere near other persons or objects. The best choice for indoor use is provided by centuries old, lighter-than-air (LTA) framework.
You are probably familiar with the zeppelins, "rigid" LTA aircrafts that have internal frames made from lightweight materials. Our solution, blimps, are "nonrigid" aircrafts made of huge gas envelopes that take their final shape when filled with gas. Standard materials used for constructing blimps are metalized nylon, mylar, or vinyl. Mylar is typically used on smaller blimps while vinyl is the best for blimps over 10 feet in length. There are many different styles and shapes that can be used, from flying-saucer to typical "Goodyear"-style. Constructing a blimp is easy, and all you need to do is to cut the appropriate piece of mylar and heat seal it using an ordinary household iron. Another solution is to buy pre-assembled blimp bags. West Coast Blimps & Electronics sells a variety of such bags, ranging in size from 3' to over 30'. The bags can be purchased in non-assembled form starting at approximately $12.00. Larger pre-assembled bags cost between $30-$5,000+, depending on the size, shape and type of material the bag is made out of.
Other companies like Mobile Airships, Inc. sell completely assembled, ready to fly blimps equipped with R/C transmitter-receiver pair and small electric motors with propellers. Cheaper models will typically use two channel hand held R/C transmitter and two motors, while more advanced models use 3 channel control unit and three motors: the motor and propeller on the left and right of the gondola move the blimp forward/backward and mix to move the blimp right/left. The third motor and propeller beneath the gondola move the blimp up/down. An excellent source for all types of R/C blimps is DraganFly Innovations, with prices ranging from $50 to $950 for fully equipped blimp with micro B&W; wireless video camera. Airship & Blimp Resources also features a site containing information specific to remote-controlled airships and blimps.
Blimps are filled with helium, which is a very safe gas, unlike highly flammable hydrogen. It can be purchased in the form of party balloon canisters, containing approx. 9 cubic feet of gas. Helium lifts approximately 1 ounce per cubic foot of helium, so you'll have to be very carefull with any extra weight. Small video cameras, transmitters and other sensors can be added to your robot, but you'll probably have to run more intensive processing tasks off-board and to collect all the necessary data by a wireless link. Schematics for a simple RF control systems can be found at Reynolds Electronics. Super Circuits features a nice assortment of cameras and transmitters - you can buy micro B&W; camera for less than $40. Also, beware that blimps typically cannot be used outdoors, as the slightest breeze is enough to take control of a blimp.
Blimps have been used for years in various telepresence projects, like the one described at q. The Robot Group, based in Austin, Texas, exhibited a series of robotic blimps named Mark I to Mark IV. It used ultrasonic sensors and neural network navigation system. Blimps are also used in neuromorphic engineering, a young field that is based on the design and fabrication of artificial neural systems whose architecture and design principles are based on those of biological nervous systems. This report describes construction of a large neutral-buoyancy dirigible with on board PIC processor, video camera and transmitter, with control allocated to a remote PC running IQR421 software.