Various Input Devices
🎯 Trackball & Spaceball
As the name implies, a trackball is a ball that can be rotated with the finger or palm of the hand, to produce screen-cursor movement. Potentiometers attached to the ball, measure the amount and direction of rotation. Track balls are often mounted on keyboards. While a trackball is a two-dimensional positioning device, a Spaceball provides six degrees of freedom. The Spaceball does not move. Strain gauges measure the amount of pressure applied to the Spaceball to provide input for spatial positioning and orientation as the ball is pushed or pulled in various directions. Spaceballs are used for 3D positioning and selection generations in virtual reality systems.
A joystick consists of a small, vertical lever (called the stick) mounted on a based that is used to steer the screen cursor around. The distance that the stick is moved in any direction from its center position corresponds to screen-cursor movement in that direction. Potentiometers mounted at the base of the joystick measure the amount of the movement, and springs return the stick to the centre position when it is released. One or more buttons can be programmed to act as input switches.