The center of rotation is one of the most important factors when it comes to simulating G-forces. It concerns the so-called “parasitic forces”. To clarify this a little, a small example: If you virtually drive through a left turn, the simulator leans to the right. This means that the body is also pulled to the right by gravity. Since the image on the screen still tells the person inside the simulator that they are upright, this creates the impression in the brain that they are being pulled to the right by centrifugal forces and not by the inclination of the simulator.< /p>

The problem, however, lies in how the movement is carried out and how one gets to this point of inclination. Another example: When entering a curve, the car has neutral lateral acceleration. You turn and the acceleration increases. The simulator also moves. Now, when the car is actually thrown into a corner, the simulator actually has to move very quickly because the car can change acceleration much faster than its position - essentially instantaneous. But the simulator uses the position to simulate acceleration, which is why it tries to reach another position immediately. During this movement, various forces act on the body that it would not be exposed to during a purely sideways movement - the “parasitic forces”.

The goal is to minimize these forces - parasitic forces - because they tell the brain that something is wrong.

This is where the center of rotation comes into play, which makes the crucial difference in our simulator.

Imagine a simple motion platform that only moves back and forth, similar to those where only the seat moves back and forth. The center of rotation, i.e. the point around which the movements revolve, is very low in this case. The pivot point is a few cm below the seat. Your head is perhaps a meter away from this pivot point, the center of rotation. When moving quickly, the head is subjected to more lateral movement than the rest of the body, which is closer to the center of rotation. But what's worse is that if the center of rotation is underneath you, this movement will be the opposite of the intended force! Let's imagine you're driving through a right-hand bend. This means you need to simulate a lateral force pulling you to the left. To do this, the simulator must throw your entire body to the left at maximum speed. While in a real car your head would be pushed to the left, here it is initially pushed to the right! The result is that with a low center of rotation, any desired movement begins with a jerk in the opposite direction. Additionally, a lot of energy is wasted moving simulator mass back and forth unnecessarily. This discomfort often leads to you feeling sick. Imagine driving your car through a right-hand bend, but for the first tenth of a second you feel like you're being thrown to the left.

Racing simulators with rotation centers below the seat essentially provide the exact opposite of the intended acceleration at the start of each movement.

OUR center of rotation is therefore approximately at shoulder height and, depending on your sitting position, slightly in front of or behind the shoulders. This means that the head hardly moves but the rest of the body moves directly in the right direction. As a result, the vestibular system in the inner ear, which is responsible for controlling balance, moves very little, which leads to minimal parasitic forces at this point and correct parasitic forces on the buttocks (the “butt meter”).

Conclusion:

The geometry of our system allows us the flexibility to transmit forces to the rider that correspond to what they would feel in real life, without overlaying you with opposing forces at the beginning or end of each movement.

The 401cr has something other simulators don't have: a high quality one-to-one ratio between vehicle rotation and simulator rotation, with no washouts or opposing forces.

Yaw motion is one of the most critical forces a driver feels on the track. She helps him feel the car sliding. But there's more: it tells him where the car is in space and where it's going.

The 401cr gives riders exactly what and only what they expect! It gives them the freedom to drive instead of translating the signals from the simulation and the simulator.

From our animation you can see that the simulator with the limited rotation axis reaches its limits early in the right hairpin bend, causing the movement to pause before it suddenly starts moving again after the corner exit. The driver feels his car stop turning in the middle of the curve because the movement has reached its limit. In the second half of the curve it therefore feels as if he is already going straight and is no longer turning, and while the simulator is driving back to the center position, the driver feels as if he is turning to the left while this is happening But the car goes straight!

The lower the rotation range, the worse the problem of feeling something when you shouldn't feel anything. And that's the only thing worse than not feeling anything when you should be feeling something.

The yaw behavior of alternative simulators is almost always below the +/- 30 degrees shown here as an example. In the best case, the driver will experience reduced rotation. In the worst case scenario, they turn in one direction while the car is going in another direction.

For example, when driving through an oval, the car rotates 360 degrees. The 401cr makes exactly the same rotation as the car, a continuous turn. While from halfway through the lap at the latest, a limited yaw simulator (due to the seat being moved back to the center axis) gives the feeling that you are turning right while the car continues to turn left or drive straight ahead. And there are no tricks that can compensate for that.

Some argue that simulator yaw applies to slip angle (sometimes simulator manufacturers try to rename yaw as the “loss of traction” axis). But 1:1 yaw feedback significantly helps you position the car even at zero slip angle. You can feel the apex instead of seeing it.

In addition, a 1:1 ratio is required when there are many small steering corrections in addition to a large, rapid turn.

This is something that a limited yaw simulator cannot handle. But it is absolutely important to be able to understand cars at the limit.

Only continuous rotation can do that.

Our 401CR motion system provides large motion range that truly simulates forces, delivers high-impact acceleration, and has best-in-class frequency response that helps eliminate motion sickness. And we support an industry-leading and ever-growing list of simulations and games.

We compared raw simulation output from iRacing with real-world accelerometer readings taken at head level in our motion system. A seat pusher will just show some random-looking wiggles, since there isn’t any consistent representation of g-force loading, but with the 401cr you can actually see a solid correlation between the traces:

The top trace is accelerometer readings from the 401cr. The bottom trace is the simulation output.

The 301 and 401cr are as close as you can get to replicating the real feel of a car.

Want to see for yourself? The raw data we captured is available on request.