Motion simulators can be classified by whether the occupant is controlling a vehicle (such as in a flight simulator for pilot training) or is a passive rider (such as in a simulator ride or motion theater). Examples of occupant-controlled motion simulators include flight simulators, driving simulators, and hydraulic arcade cabinets for racing and other video games. Passive ride simulators include theme park attractions where a projection screen sits in front of riders.
The Sanders Teacher, one of the first motion platforms, was created in 1910. This model aircraft was connected to the ground by a universal joint, allowing a pilot in training to use control surfaces to move the model in pitch, roll, and yaw when wind was present. In 1929, Edwin Link patented the "Link Trainer," which used organ-type bellows under the simulator cockpit, controlled by the pilot's stick and rudder, to provide movement in pitch, roll, and yaw.
In 1958, a flight simulator for the Comet 4 aircraft used a three-degrees-of-freedom hydraulic system. The development of hydraulic systems continued, with significant advances in motion platform technology. By the 1980s, hydraulic motion simulator arcade cabinets became a trend, sparked by Sega's "taikan" (body sensation) games. Sega's first motion simulator cabinet was Space Tactics (1981), a space combat simulator with a cockpit where the screen moved in sync with the on-screen action.
Motion platforms are used in engineering for analysis and verification of vehicle performance and design. By linking a computer-based dynamic model of a system to physical motion, users can feel how a vehicle responds to control inputs without building expensive prototypes.
It is physically impossible with most existing systems to correctly simulate large-scale motion in the limited space of a simulator. The standard approach is to simulate cues of initial acceleration as closely as possible. Washout filters are used to suppress unnecessary low-frequency signals while returning the simulator to a neutral position at accelerations below the threshold of human perception.
Human perception of the body and surroundings results from the brain interpreting signals from sensory systems such as sight, sound, balance, and touch. Postural stability is maintained through vestibular reflexes, which are controlled by three classes of sensory input: proprioceptors, vestibular system, and visual input.
The use of physical motion in flight simulators has been a debated and researched topic. A series of tests conducted by the engineering department at the University of Victoria in the 1980s found a definite positive effect on how airline pilots perceived the simulation environment when motion was present.
Motion simulators are used in theme parks and amusement parks to simulate flight or other motions for guests. Examples include Star Tours: The Adventures Continue at Disneyland, Body Wars at Epcot, and Wild Arctic at SeaWorld Orlando and SeaWorld San Diego.
Motion platforms are commonly used in flight simulators used to train pilots. They are also used in military and commercial flight instruction training applications. In entertainment devices, motion platforms are used in theme parks, with users ranging from single people to many, seated in rows in front of screens in which pictures are projected, synchronized with motions from the platform.
Some driving and flying simulation games allow the use of specialized controllers such as steering wheels, foot pedals, or joysticks. Certain game controllers designed in recent years have employed haptic technology to provide real-time, tactile feedback to the user in the form of vibration from the controller. A motion simulator takes the next step by providing the player full-body tactile feedback.
Although washout filters do provide great utility for allowing the simulation of a wider range of conditions than the physical capabilities of a motion platform, there are limitations to their performance and practicality. Washout filters take advantage of the limitations of human sensing to the appearance of a larger simulation environment than actually exists.
Simulators provide a safe means of training in the operation of potentially dangerous craft (e.g., aircraft). The expense of training on real equipment can sometimes exceed the expense of a simulator. Time between training sessions may be reduced since it may be as simple as resetting the motion system to initial conditions. However, the true environment may not be mimicked identically; therefore, the pilot/rider may be confused by the lack of expected sensations or not properly prepared for the real environment.
Degrees of freedom (mechanics), Driving simulator, Full motion racing simulator, Flight simulator, Kinematics, Simulator sickness, Stewart platform, Vestibular system.
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