He fed in pictures of the animals through an artificial intelligence process called machine learning and finally, the device worked.
The camera spotted a badger, and the high frequency sound went off to send the unwanted night-time visitor on its way and leave the garden clean for Mr Milward's children to play in.
But ultrasonic animal deterrents are not without controversy.
The RSPCA has long-objected to them, stating: "Noise levels produced by such ultrasonic devices are likely to be aversive to some animals, potentially causing them discomfort, fear and/or pain and predicting an individual's response is difficult."
Mr Milward said he "recognises the importance of living harmoniously with wildlife" but just wanted a humane way of protecting his two young children from the mess left by foxes and badgers, while also preserving his garden.
The IT expert said he thought the technology could have much wider applications than a back garden in the home counties.
"In agricultural settings there aren't really any safe deterrents for getting rid of potential predators, and this is an ideal solution for that," he said, adding that a similar system could be used anywhere where humans and animals come into conflict.
Mr Milward said he was not looking to profit from the Furbinator and instead has made his code open source, external.
While he may find a wider audience for the device, he admitted at home his wife did not quite share his zeal for his pet project.
"I think she's quite perplexed as to what I'm doing," he said. "But she's very much used to me going down these crazy paths to solve what would seem a very simple problem."