PlayStation Move – More Advanced Motion Sensing for Games

The PlayStation Move is Sony’s entry into the world of motion-controlled gaming (unless you count the EyeToy camera, which was available for the PlayStation 2 and made simple camera-tracked motion gaming possible, much like any webcam). It is a peripheral for the PlayStation 3 home video game console.

The Move is a wand-like controller, equipped with a glowing soft rubber orb for visual tracking and several internal motion sensors for further motion sensing.

The PlayStation Move motion controller

The orb is lit up by full-range RGB LEDs, which allows it to glow with any RGB color (except very dark colors, since the rubber is itself white). This orb is tracked by the PlayStation Eye camera (a USB camera made specifically for the PS3), and through software its position in 3D space can be accurately calculated; its position along the horizontal and vertical axes is calculated by its position in the 2D image captured by the camera, and its position along the depth axis by its relative size. Thanks to the orb’s ability to light up in any color, several Move controllers can be tracked simultaneously and individually by assigning them different colors.

The PlayStation Eye camera

The PlayStation Eye camera

Combined with a couple of internal sensors (an accelerometer for measuring tilt and acceleration, a gyroscope for measuring rotation, and a magnetometer for calibrating the controllers orientation against the Earth’s magnetic field), the controller can be tracked in a way that allows both its position and orientation to be displayed 1:1 on the screen, after initial calibration. Even if the orb becomes obscured from view, the internal sensors can still keep track of how the controller is moving (although the 1:1 3D positioning is obviously dependant on the orb being in view).

This is a far more advanced and accurate type of tracking and motion sensing than that which Nintendo’s Wii Remote controller allows for.

The Wii Remote motion controller

The Wii Remote motion controller

The only internal motion sensor the Wii controller contains is an accelerometer, and thus it can only sense tilt and acceleration (though it did gain the ability to sense rotation through the addition of the separately sold Wii Motion Plus peripheral, which contains a gyroscope). It also has a low resolution IR camera, which is used to give the controller relative pointing abilities by tracking a “sensor bar” (which is an array of IR diodes, and not a sensor in any way despite its name). In a way, this setup is the opposite of what the Move uses (where a stationary camera is tracking the controller, instead of a camera in the controller tracking a stationary object). The Wii controller is not capable of 1:1 3D positioning like the Move controller, since there is nothing tracking its actual position, only its relative motion.

– Joakim Melkersson / Group O

Photos courtesy of Wikipedia

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