A REVOLUTIONARY homemade unmanned aerial vehicle is being used by the Department of Food and Agriculture in Albany to help eradicate a noxious weed threatening local bushland.
The “quadcopter” enables weed control workers to carry out “search and destroy” missions on Sydney Golden Wattle trees that are difficult or impossible to reach by conventional means.
Unknown in Albany before the early 1980s, the wattle is now at plague proportions and will have overrun more than 20 per cent of native bushland by 2020 if left unchecked.
The invention is the brainchild of department senior research officer John Moore, who designed and built it over 18 months.
Mr Moore used readily-available, inexpensive high-tech gadgetry and computer components to create the quadcopter for about $1000, a tiny investment when compared to commercial equivalents that can cost up to $30,000.
Popular among aviation hobbyists, the quadcopter has been around for some time.
What makes Mr Moore’s version unique is the way it has been set up to not only locate small stands or individual weeds, but to photograph them and then spray them with weed killer.
The power plant for the quadcopter’s four rotors is a small rapid-discharge battery powerful enough to start a car.
It provides enough energy to keep the quadcopter in flight for about six minutes, depending on the weight of the weedkiller bottle it is carrying.
The flying machine is piloted by using a remote-control box with joysticks that control altitude and direction, fire the attached point-and-shoot camera’s shutter and activate the chemical sprayer.
Mr Moore says the quadcopter employs a three-axis digital gyroscope similar to those in wristbands used in digital action games such as sword fighting, tennis or golf.
The quadcopter also uses a barometer to measure altitude, a magnetometer to establish compass direction and a sonic proximity detector, similar to the ones used when reversing cars, to indicate how close it is to a weed.
“If someone’s got an GPS point from aerial photography, we can send it there. It will take off and fly straight to it and then hover above it.
“Then you can use the camera to be sure you’re right above the tree you want to spray.
“It can also fly over a plantation, and look for a wattle … it’ll send back a photo to the laptop that can be analysed to establish the location, then it can drop down and spray it.”
The quadcopter is also used to eradicate other noxious weeds such as blackberry and gorse.