Simulator

Technology

A simulator is a technical device making it possible to reproduce in a virtual way the behavior of a real phenomenon. It thus presents under controllable and observable conditions the evolution of the model of the phenomenon: if there exist several models one can also speak about system in a more general way.

A simulator is thus the tool of implementation of the simulation of the system with all the advantages and disadvantages that implies. In particular a simulator will be used when the real system is inobservable or not easily observable for all kinds of reasons (dimension, safety, cost, inexistence…)

Classification

Several classifications of simulators are possible. We propose simplest who is to distinguish:

the simulators in which the man intervenes only upstream of simulation for the parameter setting and the initialization of simulation:

it is a simulator not controlled which can be for example a electronic simulator of circuit. They are called sometimes numerical simulators and they always do not require to be Real-time .

simulators where the man is in the loop of simulation:

it is a simulator controlled (or interactive ) which can be for example a flight simulator which simulates the flight of a plane with a real pilot with the orders. He will require to be perfectly real-time . sometimes

one gives to the Virtual reality the same definition as that of the controlled simulator, which is completely licit when the models evolve/move in real-time .
there exist particular cases where simulation is superimposed on a real environment which it enriches. One rather speaks about increased Réalité than of simulator.

Simulator not controlled

If simulation proceeds on one or more computers, in the form of a software, the term simulator will very often indicate the software itself. The parameter setting and the observation of simulation will not require special devices inevitably. When the results are presented in 3 dimensions, the observation is done more easily with the tools of virtual reality.

Controlled simulator (or interactive)

If the man is placed in the loop of simulation real-time , the objective is to make him control the simulator: following its actions, simulation will calculate the effects simulated on the system and the physical interfaces of the simulator will provide to the pilot the perceptible results of his actions.

For these interfaces, the techniques of virtual reality are used.

One distinguishes in particular:

the visual interface which presents to the pilot the current state of the environment in the form of synthesized images
the sound interface able to restore the sound effects of the situation
the proprioceptive interfaces which address in particular to the physical feelings orientation grace to the internal ear, with the muscular efforts and the touch:

the Haptic interface to restore with the pilot the efforts which it will be able to feel on the orders of the simulator
the interface Kinesthésique to make feel with the pilot the effects of displacement in the virtual scene, accelerations and the vibrations on his body.

According to the uses of controlled simulation, one distinguishes:

the simulators of studies and/or research (transport, nuclear power, surgery, soldier…)

for the design, the development, the study of the ergonomics of the systems
for the study of the human behavior (safety, vigilance…)

the simulators of Formation (transport, nuclear power, surgery, soldier…)

for initial training and/or continues, the drive of the professionals (frequently) and/or of the general public (very seldom)

the plays of simulation

The complexity of the simulator depends on the use which is made by it. The restitutions with the pilot can be partial. For example certain flight simulators do not have kinesthetic interface: it is said that they are “at fixed base”, i.e. the pilot perceives his movement only using visual perception.

The essential difficulty of placement of the controlled simulators is them Validation : even on simulators using of the very sophisticated devices, the restored environment is very far away from reality and can induce oblique in the behavior of the pilot and his perception of the situation. For example:

the definition and the luminosity of the systems of presentation of synthesized image are very distant on the one hand from the capacity of discrimination of the human eye and on the other hand photometric characteristics of a real scene
the accelerations and displacements possibly restored by the simulator are constrained by dimensions and the limited performances of the system of restitution of movement.

The validity of the transfer between what was learned or observe out of simulator and the real situation is always the fundamental question which a professional user of simulator must raise.

Internal bonds

Simulators of piloting

Flight simulator
Simulator of control automobile, railway, maritime, equestrian, Russian mountains,…

Simulators of control of nuclear plant, control tower,…
surgical Simulator

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