The plan !!!

Research overview.

After building the old platform, I knew the new interface system HAD to have expandability, be cheap and readably available.

Erich and I searched the net, looked thru catalogs and conjured up our own diagrams, just about exhausted our selves with research.

There are a few contenders out there but there was always a weak point or a failing in most of them to suit “the plan”.

The specs we used were (Well, Erich’s were slightly different to mine)

1/. Initially, drive for 2 motors.

2/. Be able to handle up to 24 volts at 15 amps. (Short term peak, to suit my MKIII platform)

3/. Had to react fast to signals from the software. ( For the motors)

4/. Have inputs for platform position sensors etc.

5/. Have other outputs for other things. (Bump generator, Yaw motor, seatbelt tightener, Gear LED’s, flap indication etc)

6/. Have other inputs for other things (Gear, flaps etc)

7/. The ability to run multiple boards as the system “grew”. (A VERY important point, a lot of boards only allow 1 board per PC)

It quickly became evident that getting one board to do the lot (and be cheap) was a bit of a pipe dream, so we opened up our search for research into the theory of running 2 boards. … This (separate board for the motors) ended up being an advantage in the long run.

There was a solid excursion towards the Picaxe 28X for a while, but in the end this was ruled out.

The Velleman K8061 would have been a better board than the K8055 due to the response time (4 ms as against 20 ms) but was ruled out because it only had one PWM outlet, wasn’t so widely available and it was a LOT !! dearer. (3 times the price !!)

We both done an excursion into the pro’s and con’s of using joystick inputs for the position sensing but decided to go for a Velleman card as it gave all the other benefits as well. (Inputs & outputs)

After months of pondering to build or buy, “in-out” cards we finally chose 2 cheap and easy options …

The Velleman K8055 ( or Velleman VM110 or Jaycar KV3600 )

http://apogeekits.com/usb_interface.htm

http://store.qkits.com/moreinfo.cfm/K8055

These kits are widely available through-out the world so do a search for them locally.

These boards are USB to the computer and allow the input of the pots that measure the pitch and roll positions of the motion platform.

There are also 5 digital inputs, 2 analogue (or PWM) outputs and also 8 digital outputs, all of which will be used for something as time goes on.

Up to 4 boards can be run from the 1 computer but with my software, I am initially only using one

The jury is still out what all these in/outs will be used for but possibilities are …

Digital outs… Yaw motor, bump generator, seatbelt tightener, LED indication of anything .. etc etc.

Analogue outs … Meter indication of anything (Flaps position?) variable drive for anything.

Digital ins … Inputs for switchs for anything, also maybe interlocking switchs for the other “outs”.

UPDATE Feb 08 (On the Velleman)

This card has worked flawlessly although I not using it for much at the moment.

One thing I have noticed is the “lag” with the position pots reading coming back to the computer. With the type of planes I fly there isn’t a problem as the lag gets absorbed into the “spread” at anyrate. As things get “busier” for this board I hope it doesn’t add to the lag. If it does then I might have to revisit this.

And the other board …

Ocean Controls kit No KT 5198

http://www.oceancontrols.com.au:80/motor_controller/dc_motor_controllers.htm (Look for KT5198)

http://store.qkits.com/moreinfo.cfm/KT-5198A

When you actually look at what these cards do, it is amazing its all in one board and so cheap !!!

There is a huge advantage in that they can be multi-dropped. (You can run 4 of these boards from 1 serial port) and of course, if you don’t have a serial port on your new computer, you can use a USB to serial converter. (Cheap)

I am only using one board for my initial setup and using the serial input.

Inputs are via analogue 0 – 5 volts or RC or serial. … Outputs are for 2 motors and after beefing up the tracks (and adding heatsink and/or a fan) can handle more than enough current and up to my 24 volts required.

For high current, direct connection onto the tabs of the mosfets is another option.

The RC input should be a “draw card” for the guys out there that are already using that system.

These boards are just what we were looking for. I have tested these boards and have no complaints as it does what it says it will do, although I have yet to set it up for high current use. At the moment, while I am programming, I am using 12v lamps with diodes for direction indication.

UPDATE Feb 08 (On the KT5198)

I thought I would pass on my experience with these boards to date.

Early on in this mission I blew up a couple of mosfets and I was starting to wonder of my choice here was correct ,,, BUT it turned out to be my fault totally.

Once I cottoned on to what the problem was ,, no more trouble, so I went back to developing the software.

During this period, this board has been subject to terrible abuse and it survived.

Normal use is about 7 or 8 amps. (Per motor)

Heavy extreme use was about 15 amps (Per motor)

When things went wrong for some reason, and the motor went to the extreme stops, the amp meter would slam across to 25 amps which is the maximum it reads.

I am pleased to say ,,, it survived and I am more than happy with them, as they are, except you need to fit heat sinks and a fan if used like I have.

The General Layout

All in all, another approach was to use the Velleman card PWM outputs and directly drive the 5198 or some other card for the motors, but this was ruled out due to the 20 millisecond response delay going thru the Velleman. It was better and quicker to feed the 5198 directly either thru the serial port or with a serial to USB adaptor.

Builders of motion platforms need the response time kept to an absolute minimum to reduce the “lag” effect of what visualization you see on the screen to what you actually feel, so adding 20 ms was not really an option. (Yes, that’s 20 one thousands of a second !!!!)

Software.

I am developing my own software that will be totally user configurable … so this setup can be used for (say) a jet and then with a couple of mouse clicks it will recover a previously saved ini file and change it all to (say) a Cessna.

All speeds, softstarts, softstops etc are user adjustable to suit different types of platforms (Motors, rams etc) and then you save them to an ini file.

I am using Visual Basic and it communicates with simconnect. Outputs are a frame rate speed.

Well, I suppose you could ask why I posted this ??? Well the concept is so simple and versatile, I just thought I would toss it out into the flightsim community and see what happens. It is so simple, it makes my older FS9 system look so complicated. !!!!!!

My motto … “Cheap and easy” !!!

Note: The screen grabs are copywrite of the respective owners.

Updated 3-Feb-08