Tutorial Simple Digital Scope for Motion Sim Testing

Here is a basic Digital Scope specifically designed for use with motion simulators. It’s primary purpose is to help you understand how well your motion simulator is tracking the motion cues sent out by the game via Simtools.



Some details:

• Can monitor Simtools output without any additional hardware
• Requires a dedicated Arduino UNO (others may work but untested) to monitor your Simulator motion
• Can be used to monitor any controller – Arduino, JRK, others (as long as they use 0-5V POTs as feedback)
• Monitor up to 3 motors at once
• Minimal setup required
• Configured for use with Simtools
• Track and compare position targets and motor feedback
• Can run on a separate networked computer
• Easily create .bmp snapshot of the chart display

Setting up:

(*** If you just want to monitor Simtools output you can skip the Arduino steps ***)

Step 1 – get yourself a spare Arduino UNO and upload the SimpleScope.ino sketch file (included in .zip file)
Step 2 – copy the motiontrack.exe and motiontrack.ini to the computer you plan to run it on
Step 3 – update the motiontrack.ini file with the correct comm port number that your SimpleScope Arduino connects on
Step 4 – connect the SimpleScope Arduino to the computer and start the motiontrack.exe program

At this point the MotionTrack should be running and receiving data from the SimpleScope even if though SimpleScope is not connected to your Simulator. In the bottom right of motiontrack.exe you should see that it is receiving serial data at approx. 500 pkts/sec. If this is very different there may be a problem. At this stage there will be 0 pkts/sec UDP data because we haven’t set it up. If you touch one of the bare wires connected to SimpleScope AN0, AN1, or AN2 inputs you should see movement (noise) on the MotionTrack display.

Step 5 – carefully connect the GND wire of SimpleScope to a GND on your simulator (make sure you don't touch any power signals)
Step 6 – carefully connect one of the SimpleScope input wires (AN0, AN1, AN2) to the center pin of a motor feedback POT

At this point you should be able to monitor the actual movement of your simulator. Give it a try, run a game and see if the motor position is displayed on the MotionTrack screen. You can connect upto three motor POTs. There are checkboxes at the bottom of MotionTrack screen that enable you to turn on/off the various signal traces. These inputs are the motor “Actual” position traces. Once you have this working continue on to setup Simtools so the “Target” positions can be displayed by MotionTrack. MotionTrack gets this data from Simtools using a UDP interface.

Step 7 – open Simtools Game Engine and goto a new “unused” interface tab
Step 8 – setup for NET interface, enter the IP address of the computer running MotionTracker, use 127.0.0.1 if on the same computer. You can also use 192.168.1.255 to broadcast to all 192.168.1.xxx IP addresses.
Step 9 – Enter UDP Port 20017 (unless changed in motiontrack.ini)
Step 10 – Set for 16bit binary output
Step 11 – Output string [<Axis1><Axis2><Axis3>] and set 1ms delay.
Step 12 – Save the settings

You MUST include all three Axis in the output string even if you don’t use 3 axis. If all goes well, when you now run a game the MotionTrack should show approx. 500 pkts/sec UDP data in the bottom left of the screen. You should also see the “Target” traces on the screen moving as you drive round the track.



Ideally the “Target” and the “Actual” signal traces run exactly on top of each other ie perfect tracking. This will be unlikely but the goal is to get it as close as possible by tweaking your controller setting or adjusting the simulator mechanical arrangements. If your controller does any scaling to the target or feedback signals then this will be seen as the target and feedback appearing on screen with different scales – if this turns out to be a common problem I will look for a solution.

Use the checkboxes to turn the respective traces on and off.

The "Invert" checkboxes flip the "Actual" traces upside down - use this if they are moving the opposite direction to the "Target" traces.

The "Align traces" checkboxes move the "Actual" trace directly on top of the "Target" trace at the point in time you click the checkbox on. If it doesn't look right click it off and on again. This is best done when the game/simulator is parked - ie running but not creating any movement.

I would be curious to see the results from different setups to see if there are any particular mechanical or controller setups that inherently track better than others.

you have more time than me

Very good idea @RufusDufus
I'll try this as soon as I got a new simulator!

By the way, I was thinking on something that could be complementary... but it will wait after my sim building!
yours

This looks to be very useful for members that are having problems they need to solve or just want to know! Thanks for the effort you put forth @RufusDufus !

@bsft, @eaorobbie, I have responded here to avoid continued hijack of other thread...

I just had a closer look at Simtools output with different packet delay settings using the MotionTrack above and see what you mean. I had assumed that because it had a 1ms option that is what was coming from the games.

Thanks for the info.

This can be already be done within the Jrk software without connecting anything extra or having SimTools send anything extra too, but will be handy for testing other systems.

Some axis labelling and sizing would be handy or like the jrk allows us to actually just track the error of the two values, thus allowing you can change the pid on the fly while tracking the error to tune it to a min.
Handy , I have my error down to under 2% of the pots value now Im not using halls anymore , before couldn't get it under 8% because of the noise on the Hall effects.

Nice project.

Will run a test thou, why not.

Hi,
another beautiful and very useful application for DIYers!
Congratulations! good idea!

Definitely sabertooth + kangaroo is not made to operate a racing sim. (good for a flight sim but not a racing sim!). When I replaced my S+K by my MM+Arduino (SMC3), the difference was huge. Sabertooth works fine but the response time is too slow. I've never been able to feel the little bumps as with my MM. Here are some images that speak for themselves.

With MM on a F1 at Spa.:



MM again at Spa :



and now sabertooth :



Thanks @RufusDufus for your digital scope !

Eric

@ericRacer, the MM looks like it is setup very well. A great example of how well they can work!

The sabertooth looks like something is not working? more like it is just producing random shaking than actual motion tracking?

Good to see someone using the software... The reason I made this software is so anyone can see how well there setup is performing which is useful if you have never tried anyone else's for a comparison. I suspect there are alot of sim users out there that could tweak there setups to get better results?

I totally agree. See, what's really going on with our engines versus the signal is a necessity. For me it was the day and night difference. I used my Sabertooth long for the simple reason that they were more powerful than my MM, 2x25amp and connected to 24v. but I did not realize that I was losing all the small details. Now it only remains for me to wait for my new MM and connect them in parallel to obtain more power.

Your software is very good and useful, it should be sticked.

Excellent work. Very useful application for the non-JRK users out there. I could not have reliably setup my PID without a similar system that comes with the JRKs utilities. Remember the Optimum PID will be slightly different on every SIM, due to differences in the rigs motors power&torque, axial loads, friction and inertia.

It can be very useful to set correctly the PID ! I'll test it soon. Thank you

Here are some pictures to illustrate the connections:

Arduino:


or JRK wiring:


@RufusDufus : is it correct?

Ok ! So the best way is to use 2 Arduino for me with hook gripper cables.
Maybe tonight I'll test it (my config is Arduino + Sabertooth 2x25 in serial mode)

@RacingMat
nice work and well done.
But I wonder why you drew the + 5v. between 2 Arduinos, I do not see the utility of it they are already connected via the usb cable and gripper cables needs only the ground.

@ericRacer : you're right! i've removed the 5V

Hi !

I receive my new hook gripper cables today, I hope testing them tonight.

I wonder if in the Ard code you don't need to set the range of pot (and make a map) because they are used on less than 1024 points (in my case they are using 900 points) ?
And what do you think about to set Axis on 10 bits (instead of 16) like pot to avoid a conversion ?

Bon travail.
Je vais l'essayer sur mon DIY simulateur. Je pense que c'est bien pratique pour voir si tout fonctionne correctement.
Moi j'utilise Arduino Uno avec Sabertooth 2x32.
Je posterai une image du résultat.
Merci

Good job.
I'll try it on my DIY simulator. I think a good way to see if everything is working properly.
I 'm using Arduino Uno with Sabertooth 2x32 .
I'll post a picture of the result.
Thank you

Hello,
many thanks for creating this software and tutorial. It is very detailed. I hope this will help me to find the fault in the electrics.