In a little over a decade WiFi has flourished to become something that we take for granted every time we go to a coffee shop. The only problem is that in situations where WiFi would be most useful, such as on the battlefield or in a disaster areas, it’s least likely to be available. That’s the problem being tackled by a team of seven undergraduate students at Northeastern University in Boston, MA. As part of their senior project for the Northeastern’s Capstone design program, the team designed and built a robot that can enter rugged territory and create a theoretically infinite WiFi networks as it goes.
The Northeastern University team faced three problems. First, they needed a robot that could travel over rough terrain or rubble. Second, they had to design a WiFi network that was robust, cheap and easy to deploy and third, they needed a way to control the robot as it built the network.
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The robot they came up with turned out to be a squat aluminum tank running on treads similar to those we've seen developed for reconnaissance and disarmament bots. The 40 inches (102 cm) long, 26 inches (66 cm) wide robot weighs in at 150 pounds (68 kg), can carry loads of 200 pounds (91 kg) and was designed to be, in the words of team member Glen Chiacchieri “almost indestructible.” It has a range of 0.62 miles (1 km) with twelve hours of running time on its lithium batteries. Navigation is by GPS and it has a pan-and-tilt webcam complete with night vision and microphone. The robot was designed using CAD software and then tested as a wooden prototype before the final aluminum version was built. This included a custom-designed tensioner to protect the drive mechanism when going over obstacles. All very impressive when you consider that the team member responsible for this had no mechanical engineering experience.
The WiFi network part of the system consists of a number of WiFi repeater boxes carried on the back of the robot and deployed by a solenoid latch system fabricated using a 3D printer. Because the repeaters needed to be robust and use off-the-shelf parts for maximum compatibility at minimum costs, the boxes aren’t as small as the team would like. The boxes use standard Linksys routers with open-source dd-wrt firmware and are fitted with long-range antennas, amplifiers and lithium batteries. The works are mounted in a weathertight, high-impact Pelican case. When the repeater boxes are deployed, they automatically link to the nearest WiFi source and expand the network. Since the network is decentralized and can communicate with any WiFi card, the network is theoretically infinite given enough repeaters.
The clever part of the robot’s design is that its control system uses the very network it creates. The control is a web-based interface that operates over the WiFi network and provides the operator with real-time control of the robot. From a standard keyboard, the robot can be piloted, the onboard camera controlled, repeaters dropped and a GPS map of the robot’s movement displayed. Should the robot wander outside of the WiFi network, it can then retrace its path until it reacquires the signal.
The video below shows the WiFi robot in action.