Small, cheap sensors for tracking the movement of a person’s entire body could lead to “whole-body interfaces” for controlling computers or playing games, researchers say.

Several sensors measuring about 2.5 centimetres on each side are attached to a person’s legs and arms. The sensors detect movement in two different ways: accelerometers and gyroscopes measure motion, but ultrasonic beeps are also emitted.

Tiny microphones mounted on the torso pick up these beeps, allowing a laptop computer, carried in a backpack, to calculate the distance to the sensor. The system is similar to, albeit much simpler than, bats’ ultrasonic echolocation, and together with the motion sensors provides a more accurate overall picture of body movement.