Old bloke with visons of grandeur in building a motion platform

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Hi Guys and Girls, Jerry here.


I’d like to build a 4 DOF similar to this image


So all I’ve done in the past few months is Read, Read and Read; suffice to say too much information is leading me to confusion!


Questions and more questions.


Like: the following.

At the moment we will forget about the design!


And I guess the first thing is operational Physics, mainly the lifting with movement and I have not a clue!!!!!!!!!! at my age its been 60 years since I participated in a classroom.


1/ Motors -12/24/36v or Linear Actuators

2/ Power supplies to suit- Individual or shared and or Battteries


As I understand it you need PSU with High current ability, but not sure why you need battries ( read that some systems produce back current; so do all systems need a battery?



3/ Drivers, Motor controllers or H Bridge – Jrk, Pololu Dual, Roboclaw, Cytron SmartDrive

Sabretooth, Infineon BTS7960, and of course there is Arduino.

My god this above is a minefield! I have read so many notes on x-sims forums, and very few have out of the box have had NO trouble with the above controllers/drivers!


4/ Speed controllers and hall effect adjustments (are these needed or does the microcontroller take care of this?)


5/ So becides the design of the rig, and the money it takes to be happy; what have I missed?


(and just of note; it would be easier to copy someone’s design but this is not me) I am capable of making a mess of a project by my self)

6/ Please would someone add some direction to my confusion, I would be so appreciative.


Kind regards

Jerry

Hi and Thanks for the reply.

About the design; it may be some time before I send some images, as before the design comes the building of the CNC ( I think I may have bitten off more than I can swallow) any ways I'm up for a challenge.

Thanks for the simcalc, I will read and see if I may understand.

Batteries I will add into the design.

So no clones may be the way to go.

Pots and Hall sensors; will read the attachment you sent.

thank you again
communication is appreciated.
Jerry

I will keep on saying this 'gets on Soap Box'. Don't buy MMs, for the price of real MMs just purchase Sabertooth - they come with suitable coolers and are designed to handle the regenerative issues of driving DC motors..'gets off soap box'.

@SunMingD - Your not off to a good start...I would stop spamming across multiple threads...

Hey Jerry, one other reason for batteries is peak shaving. Depending on your setup, you can have peak current demands that are more than your power supplies and house wiring can supply. Batteries can take up the slack and from looking around here, they can even be the main power source during operation. Just a note of caution, though. People are familiar with car batteries but they store a lot of energy and even though low voltage, can release it fast if you accidentally short one out. You can melt wrenches, screwdrivers, watch bands, and rings faster than many realize. Things you wear will sear right through flesh and too many have lost fingers and hands.

The back current thing is from how many of the motor controllers operate and the electrical properties of the motors. Many controllers do what is called pulse width modulation and rapidly turn the motors on and off. The speed/power of the motor is set by how much time the output spends on compared to time off. But the voltage to the motor is banging back and forth between full off and full on many times per second. The motors most use are brushed and wound armature motors. Basically big inductors. When the power to the motor is turned on, the current through the windings builds a magnetic field and that is how the motor turns. But when the power to the motor is turned off, you still have a magnetic field hanging around and that collapses. It's stored energy and it has to go somewhere. Since the electronic switch in the motor controller is turned off and the circuit is open, as the magnetic field collapses it can build really high voltages back in the electrical circuit feeding the motor. It's why brushes arc. As the motor turns and electrical contact is made and broken with the motor windings, the energy from magnetic fields collapsing creates really high voltages and that energy wants to go somewhere. That's why solid state relays and switches for inductive loads have snubbing - diodes and such to give that energy a place to go. Some of the controllers can feed that energy back into the supply. Some just throw it away. Some don't do anything with it and get hit over and over with high voltage back EMF which can damage the controller.

What the potentiometers and Hall sensors do is provide a way for the motor controller to know when it has positioned the motor according to a command. Without them the control is what is called open loop and the controller can just tell the motor to turn one way or the other with a certain speed and force. By connecting up a feedback path, the controller can tell where the motor output is and know when enough is enough and back off speed/force and stop it if it is in the desired position. All they do is give a signal back to the controller that is proportional to the output position of the motor so the controller knows what position the motor is in. The difference is that potentiometers have a wiper that rubs against a resistive film or wire coil while a Hall sensor uses a magnetic field and electronic sensing to tell the orientation of the magnetic field and thus the position of whatever the magnet is mounted to. Effectively what that means is pots are cheap but they wear and can eventually fail. Hall sensors don't wear in the sensing element but many are configured just like typical potentiometers and have an input shaft. With those kinds of Hall sensors and with potentiometers you need to use something to keep motor output shaft and Hall sensor or potentiometer input shafts aligned or that gracefully allows for the misalignment. If you rigidly mount the shafted sensors, you can wear out the simple bearing supporting the sensor input shaft. All that said, there are also Hall sensors where you just mount the magnet to the output shaft and properly locate and mount the sensor and as long as any misalignment is within tolerance for the sensing element to where it can properly sense the magnet orientation, it just works and there is zero wear.

Hope that helps some. What these things really are is exercises in high speed and accurate industrial motion control. It's a complex subject and there are lots of considerations, but it isn't that hard if you take it in little chunks.

Good luck!

Wow! thank you Zed I have read this post and I will read it a again, I believe it will help me understand more of what I need to know; even if it is in small chunks.

Thanks again Zed.

So about batteries??

Hi all, has anyone in this group run their system on batteries? ie: like solar power for the house, with a large bank of 18650 or even marine batteries.


I ask this because I would like to run 36 - 48 volt motors, and I’m told this would be a better way to have a high AMP system and stronger motors!


Feasible Yes/No


any feedback is welcome, even i you call me a fool!


Jerry

Hi again, Just reading what's in SIM tools 2.0;

So the question is Do I need
Game dash and
Game vibe

and so on?
Jerry

Game Dash allows you to make and use your own instrument panels and Game Vibe allows you to hook up bass transducers for improved effects such as driving over rumble strips. These features are only available with the Pro and Commercial licenses.
Start off with the DIY license, get your Sim running and maybe then progress to this added functionality if you still feel the desire.

Hi RandomCoder, and thank you for the explanation; any information like this I can gather will assist in making a better sim platform.

Thank you again

Jerry

Hey Jerry, an FYI if you are planning to add wind - I believe you need Game Dash to be able to do that.

Thanks Zed, not sure what is meant by adding wind? (is that something to do with passing wind: ie noise generated from a moving vehicle)
RandomCoder, suggested Game dash was for a DIY button panel; and Game Vibe was for adding sound effects.

Thanks again Zed for your input.
Jerry

Wind means an air stream produced by a fan or propeller. Such a fan can be controlled via Game Dash, e. g. by synchronizing it with the speed value of the in-game vehicle or the 'rounds per minute' value of a virtual plane's propeller.

Hey @Jerry Atrick - Markus is right. Wind is your speed through the air in roller coasters, cars, planes, etc, and using Game Dash you can get access to those values and send them to a motor controller that runs fans or blowers. The end result is you get a simulation of wind as you fly, drive, or ride. In VR it's really amazing. I'm sure it is just as big a deal with monitors.

It was my first step into this silliness. I have a bass shaker on my chair where I do my simming and thought wind would be an interesting addition. I prefer the open cockpit planes and cars so wind is a natural. Totally enhanced the experience and I recommend it. It can also be a stepping stone into more complex motion simulation and demystifies and gets you experience with plugins, telemetry, and such.

I bought my wind generator from @Avenga76 (http://www.isrtv.com/forums/topic/2...mulators-and-kitsets-for-sale/#comment-206716) because I wasn't that confident at the time and he has a really well engineered setup with flow straighteners, velocity stacks, etc. They aren't cheap but it was a great introduction. It puts out winds up to 60 mph with the Sea Flo blowers I bought here in the States and really enhances all open cockpit experiences.

The whole point of this, though, was that if you want wind, you'll eventually need the Pro version of SimTools to have access to Game Dash. But you can always start with the DIY version and get your legs, then upgrade later.

And I can't believe I didn't take advantage of the opportunity to make a joke about passing wind...

Thanks Zed, now I have an Idea what you are speaking of, might be a pretty cool action to add a bit more realism to the sim.

thanks again
Jerry

Thank you I really appreciate your input, and the information you have provided.
I will read up on what possibilities these extra features within the pro version, could provide for down the track.

But baby steps at the moment, as I'm still scribbling designs on sheets of paper, until I'm a little more confident the plans are efficient enough to start the build.

again thank you.
Jerry