Most joysticks are two-dimensional, having two axes of movement (similar to a mouse), but three-dimensional joysticks do exist. A joystick is generally configured so that moving the stick left or right signals movement along the X axis, and moving it forward (up) or back (down) signals movement along the Y axis. In joysticks that are configured for three-dimensional movement, twisting the stick left (counter-clockwise) or right (clockwise) signals movement along the Z axis. These three axes - X Y and Z - are, in relation to an aircraft, roll, pitch, and yaw.
Joysticks are often used to control games, and usually have one or more push-buttons whose state can also be read by the computer. Most I/O interface cards for PCs have a joystick (game control) port. Joysticks were popular throughout the mid-1990s for playing the Descent series and flight-simulators, although they have declined with the rise of first-person shooters which instead promote the mouse and keyboard. Modern joysticks (as of 2003) mostly use a USB interface for connection to the PC. The term joystick has become a synonym for game controllers that can be connected to the computer since the computer defines the input as a "joystick input".
Apart for controlling games, joysticks are also used for controlling machines such as elevators, cranes, trucks, powered wheelchairs and some zero turning radius lawn mowers.
1980s one-button game joystickAn analog joystick is a joystick which has continuous states, i.e. returns an angle measure of the movement in any direction in the plane or the space (usually utilizing potentiometers) and a digital joystick gives only on/off signals for four different directions, and mechanically possible combinations (such as up-right, down-left, &c.). (Digital joysticks were very common as game controllers for the video game consoles, arcade machines, and home computers of the 1980s.)
Additionally joysticks often have one or more fire buttons, used to trigger some kind of action. These are simple on/off switches.
Some joysticks have force feedback capability. These are thus active devices, not just simple input devices. The computer can return a signal to the joystick that causes it to resist the movement with a returning force or make the joystick vibrate.
Atari standard connector.Joysticks were originally controls for an aircraft's ailerons and elevators.
The name 'joystick' is thought to originate with early 20th century French pilot Robert Esnault-Pelterie. There are also competing claims on behalf of fellow pilots Robert Loraine and James Henry Joyce. The joystick itself was present in early planes, however the mechanical origins themselves are uncertain.
The first electrical 2-axis joystick was probably invented around 1944 in Germany. The device was developed for targeting the glide bomb Henschel Hs 293 against ship targets. Here, the joystick was used by an operator to steer the missile towards its target by radio control. This joystick had on-off switches rather than analogue sensors, i.e. a digital joystick. The signal was transmitted from the joystick to the missile by a thin wire.
This invention was picked up by someone in the team of scientists assembled at the Heeresversuchsanstalt in Peenemünde. Here a part of the team on the German rocket program was developing the Wasserfall missile, a successor to the V-2 rocket, the first ground-to-air missile intended for shooting down enemy aircraft. The Wasserfall steering equipment converted the electrical signal to radio signals and transmitted these to the missile.
The Atari standard joystick, developed for the Atari 2600 was a digital joystick, with a single 'fire' button, and connected via a DE-9 connector, the electrical specifications for which was for many years the 'standard' digital joystick specification. Joysticks were commonly used as controllers in first and second generation game consoles, but then gave way to the familiar control pad with the Nintendo Entertainment System and Sega Master System in 1985 and 86, though joysticks - especially arcade-style ones - were and are popular after-market add-ons for any console. More recently, analog joysticks have become standard on video game consoles and have the ability to indicate the stick's displacement from its neutral position. This means that the software does not have to keep track of the position or estimate the speed at which the controls are moved.
These devices are usually a rotary potentiometer (variable resistance) turned by the stick movement.
Specialist joysticks, classed as an assistive technology pointing device, are used to replace the computer mouse for people with fairly severe physical disabilities. Rather than controlling games these joysticks plug into the USB port and control the mouse pointer. They are often useful to people with athetoid conditions, such as cerebral palsy, who find them easier to grasp than a standard mouse. Miniature joysticks are also available for people with conditions involving muscular weakness such as muscular dystrophy or motor neurone disease.