Does your replica simulator need a motion system?

08 January 2019

A replica simulator can operate very well without a motion system. However, it makes the training environment more realistic and gives clear added value to work in certain situations. So, what will you choose?

To consider the acquisition of a movement system is to accept a number of difficulties. First the budget: compared to the cost of a simulator with a static cabin, the price can increase by 10-15% for a top of the range system. Then, the building that will house the simulator: It must support an increased floor load and have exceptional ceiling height, up to six metres for a 6-axis system.

The major asset of the movement: the realism

Finally, maintenance. Movement means friction, wear, components to be maintained and replaced. Manufacturers have already eliminated hydraulic cylinders which were complex and generated oil leakage. They now reduce the use of pneumatic cylinders, of which the compressor was the weakest link. The time has come for electric cylinders, which are supposed to be more reliable, but it will take a few years to be sure.

However, many operators are not discouraged by these disadvantages. They believe in the motion system to restore accelerations, braking, crossing switches, jolts, vibrations, and more. A driver in a real situation experiences these sensations all the time. The training environment must reproduce them to be believable.

An understated combination of movement and swaying

And it is true that it does this very well, especially with 5- and 6-axis systems. Let's take the example of slightly hard braking, during which the trainee must feel that he is moving forward.

The system will first move the cab backwards. But before it stops moving backwards, it will discreetly tip forward, at a speed of rotation below the threshold of human perception. Thus, when the cab stops, this tilting took over from the longitudinal displacement to maintain the physical sensation of braking. In his cabin, without a view of the outside, the trainee does not notice anything.


Freight trains: make you feel the impact of sudden braking

Does this technical feat guarantee that drivers will be "better" trained with a motion system? No, of course it does not. On the other hand, it is certain that the movement brings a clear added value when it comes to training in certain business skills.

The first example is braking on freight trains. Drivers know that it is important to avoid excessive skidding: tail cars, driven by their momentum, can cause violent pushing at the head of a convoy. With a static cabin, it is impossible to make a novice feel this kind of kick in the backside. While a simple 3-axis system, or even 1 axis, will produce a shock that the body and mind will remember!

Passenger trains: the movement restores the feeling of comfort

A second example is passenger comfort training. They are very attentive to the smoothness or brutality of braking and acceleration. The best way to raise driver awareness is to make them physically experience the impact of their driving. Otherwise, the incentives to slow down or accelerate "less strongly" remain meaningless. To work on such an objective, the 3 axis is no longer enough: it requires the finesse of simulation of the 5- or 6-axis, as explained above.

A third example, station stops on a marked out site within a split metre. The trainee can achieve this at the expense of suddenly braking at the last moment, a series of small accelerations and decelerations, or gradual and smooth braking. Only a 5- or 6-axis motion system will physically restore the dynamic signature of these three strategies, as well as their impact on passengers.

The seat in motion, a low-cost option

To limit the cost, some operators now choose a motion system fixed to the driver’s seat in the cabin. This solution has the advantage of costing less but also has its drawbacks: only movements of low amplitude and low intensity are realistically reproduced. However, much more is needed to cover the spectrum of train, subway or tram driving situations. This should be remembered before choosing this option.

STEPS is a blog eager to provide answers and to bring up new issues with simulation users.

Its information is based on 30 years of CORYS experience of simulation and on the feedback from our customers around the world, in the field of Transportation, Power and Hydrocarbons industries.

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