A new app for Android phones can warn users when they are about to forget their device.
Chaperoneuses a sonar-type method known as “active acoustic sensing” to detect a smartphone owner’s movements and locks the phone while alerting the owner when detecting a situation that could lead to loss.
“I was in a restaurant and after I finished my meal,I left without taking my phone,” said Jiayi Chen, a PhD candidate in the Cheriton School of Computer Science and creator of the app. “I was out the door and heading towardthebus stop when a waiter ran out and said, ‘Hey, you forgotyourphone.’ I was lucky, but it got me thinking. What if asmartphone could detectwhetherit’s about to becomeunattended andthencould alert the owner while thedevicewas still within reach?”
The app is currently designed only for Android devices as Android is open-sourced and provides more flexibility. In theory, the app would work on an iPhone or other Apple devices. An iOS version of Chaperone will be future work.
While many loss-prevention solutionsrequireadditionalhardware such as Bluetooth devices orwearableradio frequency ID tags,Chaperoneisastand-alone solution. All smartphoneshavea microphone and speaker, sotheyare capable ofperformingactiveacoustic sensing.
When Chaperone is installed onan Android phone, it uses thedevice’sspeakers to emit an inaudiblehigh-frequencyacoustic signal. It then detects the echo of that signal — its reflection fromthe phone’s owner as well asotherpeopleand nearby objects — using its microphone.Based on the changes in the reflected signals, Chaperone can distinguish nearby moving people from static objects. Then, Chaperone extracts the owner’s moving pattern and determines if the owner is about to leave the device unattended.
Toincreaseaccuracy in detection, Chaperone uses four modules before alerting its user: triggermodule(sensing user’smovement), acoustic-sensingmodule(detecting the echousingthedevice’s microphone to calculate distance and speed of movement), user-trackingmodule (locating the smartphone’s user in the immediate environment through echo filtration),and decision-making module (alerting the user if necessary).
You don’t have to worry about the alert being a blaring horn either.
“Because thealert isselectedbased on information collected by the trigger module,it’s tailored to the context,”Chensaid. “That means ifenvironmental noise islow asin a library,a gentle ringtonewouldbe sufficient to get the user’s attention.”
So far, more than 1,300 experimentsacross different real-world scenarios have been evaluated. In 93 per cent of cases, Chaperone positively detected a user leaving their phone.
“Our current solution is designed based on a smartphone running Android 6.0 or newer,”Chensaid. “The code is freely available so anyone can download it or improve it. Our experimental data and source code for our prototype is. This will help other researchers as well as let them contribute to the project.”
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