Motion System Design
Robotic metal detector may save lives

Robotic metal detector may save lives

The United Nations estimates there are more than 100 million land mines worldwide, and that more than 2,000 people are killed or maimed by explosions each month.

Looking for a safe way to locate these hazards, Carl V. Nelson, a principal staff physicist at The John Hopkins University Applied Physics Laboratory, developed sensors to help detect land mines. But he needed a device to carry them into areas of thick vegetation, where explosives are often hidden.

Four undergraduate engineering students came up with a solution. They designed and built a remotecontrolled robotic vehicle that finds mines hidden in rugged terrain and marks their location with a paint spray. The prototype has been given to professional explosive-detection researchers as a model for a low-cost robot that humanitarian groups and military troops could use to prevent mine-related deaths and injuries.

The two-piece vehicle rolls on tank-type treads. The front portion moves the robot using two cordless-powerdrill motors connected to a sealed lead-acid battery. Atop the drive segment is a color video camera that lets operators see what the robot encounters.

The second unit houses a simple metal-detection coil from an off-the-shelf metal detector, which would be replaced by more sophisticated sensors if the model is used by funded researchers. The rear segment also holds a small storage tank and spray-paint nozzle.

To steer the robot from a safe distance, the students constructed a batterypowered controller with joystick. The controller features a small video screen that displays real-time images from the robot’s camera. When metal is detected, a beep is heard over a speaker on the controller or headphones worn by the operator. A switch on the controller activates the paint sprayer.

The vehicle is mostly made of plastic and other nonmetal parts to reduce cost and weight. Using non-metal parts avoids false-positive readings from the mine detector. The two-segment design also spreads out the robot’s weight, making the device less likely to set off a mine.

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