Biomedical Engineering Reference
In-Depth Information
years to develop commercially (e.g., using the body as a human antenna for full-
body interaction [
4
], using swept frequency capacitive sensing to detect interactions
between a user's hands and ordinary physical objects [
17
]). However, regardless of
what technology is used, the focus of these devices will be to extract 3D spatial loca-
tions and motions of users to support natural, body-based interfaces. Understanding
how to use this data in locomotion interfaces is the main focus of the chapter. The
current devices we discuss here are a representative sample of devices which provide
motion and 3D spatial data that are applicable now and in the future.
Before going into the details of the devices, it is important to understand the
timeline and design approaches taken by their manufacturers. TheNintendoWiimote,
the earliest device, uses IR sensors and internal accelerometers and gyroscopes to
provide a general idea of where the controller is located and the motion it is going
through. This was designed to feel like a remote control in the user's hands so that it
had a general appeal to a wider audience, however no official SDK was planned and
the data output was very raw with little pre-processing performed. The Playstation
Move Controller arrived after the Wiimote and has similarities, in that it is a hand
held controller with gyroscopes and accelerometers so the motion of the controller
is known. The Move, however, makes use of the already existing Playstation Eye
camera to more accurately track the position of the controller's glowing orb on top.
Sony also designed the Move with a smoother surface to better fit in the user's hands
and developed an SDK that fuses all of the raw data into an accurate position and
orientation of the controller. The Kinect arrived after theWiimote as well, and slightly
after the Playstation Move, but introduced an interface that was controller-less. This
system functions by watching the user's body and recreating a skeletal representation
of them from both a colored image and depth image, all of which is available via a
Microsoft provided SDK.
Now, let us go into the hardware details of each of these devices along with
some design considerations to account for when using them, especially for full body
locomotion solutions.
16.2.1 Wiimote
The Nintendo Wii Remote (Wiimote) incorporates many useful input and output
features in an inexpensive, consumer-oriented, easy-to-replace and easy to repurchase
package. The controller also incorporates several buttons (some in a gamepad and
trigger configuration), has a speaker, programmable LEDs and a rumble device.
Because this device is easy to set up, turn on, and maintain it allows game developers,
researchers and homebrew engineers to use it as best serves their needs.
Importantly, theWiimote changed console gaming due to its ability, albeit limited,
to provide position data which altered the concept of how users interfaced with video
games. It provides three axes of acceleration data in no particular frame of reference
(FOR), with intermittent optical sensing via the infrared sensor bar. Additionally,
the Wii MotionPlus gyroscope attachment can add three axes of orientation change,
