2, 3 or 6DOF Motion Platform with VR (Rift)

[MadMonty]

Dear community,

 

medium-term I plan to acquire a motion platform. After all, there are quite a lot of offers on the market. A DIY-platform I have to rule out in any case, because there is a lack of time and background knowledge. But before I go into the purchase process, I have a general question:

 

What is the best / most suitable system for VR: 2,3 or 6 DOF? Do I get significantly more reality / fun from 6 DOF, or is a 3 (or 2) DOF platform enough?

 

First of all, I would like to leave out costs. It's all about what's best to experience VR in combination with a motion platform.

 

I look forward to your feedback!

 

Cheers,

 

MadMonty

[elecsys]

One of the more interesting 2DOF platforms that i've seen as of yet was the Accelid DS3, which seems to be some kind of a hybrid between a motion platform and G-seat.

I haven't tried it myself yet, but intuitively i thought that this might work nicely in tandem with flight sims & VR. They do support DCS.

 

 

It's an Austrian company even, so i've considered it myself.

They are present at gaming/racing conventions from time to time, so you might be able to try that thing out beforehand, if interested.

[MadMonty]

Thanks - I have already seen that platform, it looks amazing.

 

But the questions still is, if a 2DOF platform combined with a VR Headset gives you an as realistic feeling of motions as a 6 DOF would do. For example, a 2 (3) DOF has no „heave“. So I wonder, if motions like landing or taking off (which have a kind of heave-effect) or taxing on a bumby taxi way can be simulated by a motion platform without „heave“ as good as a 6 DOF.

 

Or the other way round - would I even notice the additional 3 (4) axis movements under a VR headset?

[Thadiun Okona]

Honestly if you have the money, time, space, and skill go 6dof. It's not about extreme excursions, it's about extreme accuracy in recreating accelerations to the best of a machine's ability. To that end, 2dof machines do a poor job as they tend to swing the pilot's head to and fro in an arc, which your inner ear picks up and processes but it is a false cue. Most of the time the machine is trying to use gravity to trick an accel force but problems arise as they need to travel to that position to do so, and that's what separates the toys from the tools.

 

A 6dof machine tends to have less overall range of motion, however a lot of it's movement is dedicated to cancelling out those false cues. This is done by interpolating the rotation point to the pilot's head for starters, so your head only rotates while the machine is making a pendulous arc beneath you. Another trick the 'extra' axes do is provide an initial jolt directly in the axis of accel, while the machine is setting up the gravity angle for the sustained pull and that is choreographed to be seamless. There are a host of tricks that all combine, and in the end there are good reasons entities with the money/time/space choose this type of platform.

 

Net result: your inner ear and eye maintain the best match possible, something particularly important in VR. Accurate/timely suggestions of acceleration at lower amplitude are worth far more for what you are trying to achieve than high amplitude events that lack accuracy or have false cues can provide.

 

2dof systems are neat and all, but 3dof is where things get interesting and can still be pretty convincing... heave (vertical up/down) is a lot more important than most realize. Professional training sims for flight with only 2dof are typically pitch/heave, not pitch/roll because roll buys practically nothing. You feel heave activity throughout a normal flight but only feel the sensation of rolling if you turn uncoordinated.

 

The goal of the axes are pretty much the opposite of your thought process... the additional axes are not there to be 'felt', they are there to make false cues *not be felt. I myself do not have the space or money to do a 6dof system justice, but might make a 3dof system in the form factor D-Box uses for practicality. You should hit up Trip Rodreguez, I talked him off the 2dof ledge and he built a Thanos style 6dof that he's very happy with and he posts in this forum.

 

source: mostly anecdotal observation as a long time diy simdork plus 2 years working in the industry

Edited January 13, 2018 by Thadiun Okona

[MadMonty]

Hey, Thadiun,

 

thank you very much for the detailed answer. There was a lot of things in it that I didn't know about before. My concern was that the smaller movements of a 6DOF platform don't feel as good as the massive movements of a 2DOF system. But presumably it doesn´t need this at all, as the authenticity of the movements is much more decisive.

 

I will gladly turn to Trip Rodreguez as soon as I see a platform.

 

Best

 

MadMonty