Hello & Advice - 6DOF

Hi guys
wanted firstly to say hi, new to the forum...

looking at putting together a 6DOF rig, and an occulus rift headset for a fully immersive driving simulator...

I wondered if anyone else had used the rift at all? and also I am totally new to simulators, although I do home automation and control system programming using crestron and I am familiar at a basic level with the electronics involved, although more used to automated blinds than simulators when it comes to motor control

any advice welcome.

the plan is to build something small (about the size of a single seat, with the smallest footprint I can realistically get, that is 6DOF, and an occulus rift headset for total immersion.

first question really is I am starting to read up on X-Sim.de, I am curious to know if I could interface this with a crestron processor which I was hoping to use to control the rig. (as it is what I am familiar with programming wise)...

has anyone used crestron for control before? also what type/spec of motors are people using for this sort of rig?

thanks in advance!
Oz

did you look through the threads? Heres a good start http://www.xsimulator.net/community/threads/6dof-winch-motor-flight-sim-platform.4738/

I have been browsing through, and at the moment i am most curious about using large wiper motors, or winch motors...

i am pretty sure that wiper motors will provide sufficient force given that in a 6DOF rig they are working in pairs....

the question really is whats the best way of controlling them, and given the ridiculously low cost of wiper motors it is cheap enough to just buy 6 and have a play...

I am hesitant to say that winch motors will give me 6DoF, I think they will but I can afford to experiment. That said, there is no way at all that wiper motors will give you 6DoF, unfortunately they lack the torque. The winch motors have an incredible mechanical advantage, somewhere in the range of 700:1.

I have backup ideas to get 6DoF in case winch motors alone will not do the job, this includs linear springs to help balance the load. Hopefully this winter I will be able to get back to my build and can experiment more with it. You are welcome to follow along.

But, if you want to buy wiper motors and experiment with a platform, even if it does not support you sufficiently, I say go ahead. It would be a great experience in working with multiple motors and SimTools settings.

I have already accomplished a miniature 6DoF platform using R/C servos.

Even if your platform does not turn out to support the weight that you hoped you could always just replace the wipers with winches, the controllers are the same.

For control I use an Arduino micro-controller and one Pololu 755 per motor.

Simtools has settings for up to 6 axis and is easily configurable for 6DoF.

thanks for the info, my friend and i have played with electric vehicles so i understand the torque requirements, i am still not convinced that it is impossible with wiper motors, certainly larger vehicles like vans and trucks require quite a large amount of torque in order to move the wiper mechanism, especially when you consider the forces involved purely based on the rubber on glass friction it has to overcome, not to mention losses in the mechanical movement...

i think i will buy a pair and experiment with just how much load i can move in one axis.... even if i had to double up motors, so 12 motors for 6 DOF, the motors would still come in at under £100 for 12!
i think its worth playing with i have a friend who is somewhat gifted mechanically and electronically then i do the software bits in our projects normally...

any other advice, recommendations for frame materials, rose joint sizes, tie rod/connector rod recommendations and lengths?

thanks!

oh also what about electric bike/scooter motors, they can be had for as little as £30 each...

I hope it works out for you, it would be an inspiration to us all!

As to the other items that I plan on using; I was going to go with 6"-8" armatures giving me somewhere around 10-14" of lift.

The armatures will be connected in a Stewart configuration using Heim Joints with weld-in bungs. They attach to 3/8"ID steel pipe. I figure they will have to be at least 16" to have the platform sit in a reasonable position (which means I need a ladder to get up there! lol).

The frame is going to be the same as my 2DoF platform; 1" square, 1/8" sidewall, steel tubing with welded joints.

I have been experimenting this week with building my own H-Bridge motor controllers instead of investing in more Pololu 755's. I think they will work as soon as I get the bugs worked out of the PWM interface. If they work it will cut my cost so low I can do all six H-Bridges for the cost of one Pololu 755. I can afford the Pololu drivers but DIY is way more fun!

Good luck and keep us posted!

any reason for using steel instead of ally?

would have thought you need to keep the "sprung" weight to a minimum...? (much like cars!)

probably going to get my mates at pro-alloy to make me up an ally box section for seat/harnesses/pedals/seat runner to go onto...

Just happen to have steel tube, even wood would work if that is the direction you want to go

I do not have access to aluminum, nor can I weld same.

Wipers can have the torque, but they are designed to turn I one direction, not constantly change direction like they do on a sim. Plenty of us have chewed the plastic wiper gearing out and had to move onto bigger , stronger motors.
12v boat winches are cheap , strong , powerful and noisy , but should do the job for a 6dof, but as said, historiker will look into this in time.
Winches with the right lever would be fast enough. Remember with motor shaft speed , if you have a motor of 30 rpm with plenty on lift, that would do flight , but be too slow for race. Even wipers run at about 50-60 rpm. Big worm gears I use have 140 rpm at shaft, but I would not suggest them for a 6dof. 24v motors would be good maybe.