Gravideck : 3DOF motion simulator centered on the inner ear

Greetings to the Motion Community!

I have been working on a 3DOF motion simulator with pitch and roll axes centered very near the inner ear.

The whole reasoning behind this :

low axes of rotation of pitch and roll are convenient to build ... but make the head of the user describe large arcs during transient rotations, registering as inverted translations which are confusing for the inner ear.

Right now its 3DOF to keep price accessible and also because 3DOF is already massively immersive... (but it can be expanded to 6DOF without problem)

So I know there remains a few minor kinks to iron out, but here is it in action :

Racing


Flight



Cheers

Cool. I like how the structure works perfect for the monitor. Can you show more of the build?

Enhanced realism? It will feel like on a swing. In every car you will have roll movement like on a rig. Flightsim it depends on the aircraft.

Especially for cars the rollmovement is easy to specify and it will be never in headposition. with simhub you are able to change the centerposition

You should really watch this video, Niels Heusinkveld explains very well, why pitch & roll axes under the user introduce strong inverted motion cues which are incorrect.

The core argument is very simple. When you have a low axis of rotation, your head is very distant from this axis, and is forced to describe large arcs. During transient motion, those large arcs create totally unrealistic translational accelerations.

To counter this effect ... Many high end motion manufacturers build hexapods where pitch & roll rotation axes are natively above the user, without needed to make adjustment, such as this one:



So its true that on a 6DOF, you can adjust the axis of rotation... but... What happens when you adjust the axis of rotation on a hexapod with large stroke actuators (forget about it if your hexapod has short stroke actuator) , is you start to quickly degrade its workspace, because now, the hexapod must both rotate & use surge/sway to rotate around a high axis of rotation

Then you quickly run into one of two things :

1) actuator length limitation

2) joint angle limitation



The cost-effective 3DOF simulator I built that does not need axis adjustment. The axis are natively near the user's head.

You wrote "In every car you will have roll movement like on a rig" you are referring to body roll. It is true that the axis of rotation of body roll is near the wheelbase ...but... the body roll effect only creates tiny transient longitudinal accelerations in the upper torso, that do not compare to the massive acceleration you feel when turning.

Case in point : a Formula 1 car at Monza in a very high end motion simulator

The car does not perceptibly roll, even in tight turns

I totally agree that motion simulation is an illusion. A deceitful version of reality. Basically a lie played on our senses.

For example, its totally impossible to replicate, in the current technological framework, large sustained accelerations with quickly varying directions, like in a Formula 1 or a fighter jet, even with state of the art 6DOF or centrifuges

Even automotive manufacturers cannot yet still replicate the envelope of a commercial car, they are forced to build X, Y rails dozens of meters long because the surge and sway capabilities of hexapods are far from sufficient in their view.

All that being said, I think as in all human endeavors, we are fumbling our way to general truths.

What first appear as a bizarre notion can become unassailable down the road.

There are good and bad practices that we discover through unending trial and error

Taking an example of the display technologies

I remember, back in the early 2000s, I was reading comments on the internet such as "24 FPS is all the human eye can see. There is no need for 60 FPS displays". This was very popular notion at the time.

Who would say today that high framerate is not important ? This was not obvious back then that gamers would swear by having 480 Hz displays 25 years later.

So I realize I was perhaps a bit too categoric myself but I was only pushing back at the notion that high axes of rotation are irrealistic. For I know from my personal experience that they work great.

I dont understand the point of this post.
Where did he say something absolutist and random?

Surely your talking about the troll with his swing comment instead?