Shopping list for motion platform

Hello,

I have been looking around forever for the right linear actuators at the right price and keep coming back to the SCN5 or SCN6

I'm wanting to build a flight simulator / motion platform and I was wondering if I could just get a brief overview of how the simulator software integrates with controllers and motors and the joystick etc

I've heard about Arduino boards, is this what actually controls the linear actuators?

If I'm going to have 3 linear actuators does one Arduino have the 3 inputs and outputs?

Which Arduino board would I need?

How about power supplies? Would I need one for each linear actuator?

Do I have one computer for the flight simulator software and a separate computer for the control part pf the system?

Is the SCN 5 or SCN 6 a closed loop system with position feedback?

What is the difference been dynamic and static thrust?

If I was going to be moving up to 250 lbs around does each linear actuator have to be rated for that amount?

Would it be best to have a pivot point at CG or just have the linear actuators control the platform without any other support?

I know I'm asking a lot but I think If I could get these questions answered I would have a great start and can start buying the actuators and controllers etc so I can prove them out on a bench.

Regards

Brian

do you have a particular frame design in mind?

Hi bsft,

I really like the look of this platform but with 3DOF.

Vesaro V-Spec Motion Flight Simulator



Going to be building out of aluminum tubing to keep it light.

Brian

Not really on topic, but I am wondering; which CAM software do you use?

Hi Historiker,

I've been using GibbsCam since 1984

Brian

That unit uses 4 dbox actuators which lift quite a bit, but only have a short travel and not a great deal of speed. And at $3000 each , they are a tad expensive.
As you are keen on linear actuators, SCN6 x 4 would lift a full frame as long as it is light and you are not too heavy a chap. SCN6 I think are rated to 30 kg each, I could be wrong.
12v boat winch motors or zyt90 motors with a 50:1 gearbox and suitable lever would do the job nicely and are cheaper.
For setting up Arduino and which board to use, I will let others answer that as I dont have experience in ards.
One PC will do both simtools and control , but make sure its fairly decent with at least 4 cores of good power.
Cheers, David.

You will have massive issues trying to lift things with SCN5 as they only have a 5kg radial load and can lift vertically 10kg but at 100mm/s not the 400mm/s they are rated at. Maybe a little better with SCN6 , depending on size you will get 20-30kg, but thats vertical as soon as the weight is pulling against the side ie radial they 1/2 thier spec, and break after time. Plus Ard will not run them, a Usb convertor is needed for them (off the shelf item) and plug them in and setup SimTools, in a seat mover configuration they are the ducks nuts but not cheap at all.

Build your own linear actuators and if running 12v run Jrks or higher voltages you will have to either move over to the Ard or SimAxe. But if your a machinist build ya own. Be much stronger and proberly faster, Dave and I have been looking into the subject, both just been too busy or short of funds to build a test unit.

eaorobbie,

I've even thought about going that direction too by taking a 12v geared motor, adding a short ball-screw to the end of it using a motor coupler and adding a resolver to the end of the ball-screw or mounted to the side with a small v-belt. What thoughts did you have in regards to building a linear motor unit?

Brian

Looked at ball screw myself lately, well @yobuddy has mentioned the use of them for a homemade linear actuator and the maths adds up.
Some can push with a thrust of 7200lbs, with not much torque needed. Plus they will not back turn as in will hold position without power on them, completely no backlash. So to drive them with 12 motors with a direct or geared or pully connection ( geared or pulley I would prefer as you can change the speed easily if needed) a Jrk could do this with ease, for feedback you can use a multi turn pot like a 10 turn and incorporate this into the gearing of the connection of the motor to the ball screw.

Or any 12v motor controller, I prefer the Jrk for speed and reliability and ease of setup and use.
I would start looking at diy actutors for a body build.
For example you need the ball screw in the body, 2x slide rails for a bulk head to attach to with linear bearings and inturn mounts to the head of the ball screw.
This in turn has another rod bolted to it extending out of the top plate and as well supported with a linear bearing.

Sorry if a little confusing if I had some more free time I could sketch up what I mean.

Ive just contacted an ebay seller for some suggestions. I'm guessing a 16mm OD (5/8") with 300mm travel (11.81") might work. I asked for sets of 3 with mounts and associated hardware. I'll see what sort of pricing they can come up with . I would be willing to buy a set of 3 and three of the motors from Robot Marketplace.

I could machine all the mounting hardware and try it all out.

I bet this type of configuration would far outpace and outlast the scn5 and 6 linear actuator setup.

What would you suggest to drive the motors?

Brian

The pitch of the 16mm ball-screw is 5mm ( .1968" per revolution). I was thinking about mounting the ball-screw end to the end of the motor shaft using
a motor coupler so the motor and the ball-screw would be in the same plane.

The motor RPM is 5600rpm / 60 seconds = 93 revs per second. That would mean at full speed of the motor the ball-screw nut could move 18.2" per second.
93 revs per second x .1968" per revolution = 18.2" in a second. Way too fast; this would be a rocket launcher if my calculations are correct. However the motor speed is fully controllable.

The other option is to offset the motor shaft to the ball-screw and gear it down. I'm just trying to eliminate making it too complex and the minimum amount of parts.

It's just a matter of how much the motor can handle torque wise I think.

18.2" per second is fine, thats 450mm per second, and we get that from a 45mm ctc lever on the 160 rpm big worm gear motors, perfect for race. Just settle the profile if you go for a flight.

Yes guys speed is the key of we could find a worthy driver that could match the ease, reliability and flexibility of the Jrk we would have a winner indeed.

The Jrk will handle 12v 20-30amp motors and is a full pid controller that allows us to fiddle with just about every setting including Acceleration, and duty cycle of the motor, only draw back I can see is that its not compatible with an encoder.

Myself I set them up to go as fast as it can possibly go without damaging anything and because of the brillant PID control it takes care of motor speeds and you simply tell it to move and it moves there, at the speed it requires. So speed is needed and let the controller work it out, if you had motion at a constant speed it would be like running a K8055 or bad Ard code.

My self I would not connect the ballscrew directly to the motor, as you may find you need to go a little faster or slower so having it pully drive this becomes very easy to change. Plus having the motor on the base only increase the length and makes it hard to build a easy solid mount, I would prefer to mount the motor on the side of the body as most commercial units are produced like too.

But they just my opinions, sorry.

earobie,

I'm with you on the side mounted motor. I will design it with a pulley system. I just need to pull the trigger and buy 3 ball screws on ebay. I'm looking at a 20mm option also. As soon as the seller gets back to me I'll buy them and look at getting the 3 motors also.

Is this the jrk controller you're referring to? http://www.pololu.com/docs/0J38 It looks like it has 2 motor outputs is this correct? Is there a 3 motor option?

Thanks

Brian