FINISHED! - 2DOF Wormgear Race Simulator by Arno

[motiondave]

Yes, agreed with Bob there,
I have blown many jrks from my own stupidity, but NEVER blown them from harsh use .... EVER.
They are one seriously tough little board, but like anything, they take care to initial set up. Wiring especially.
The JRK does have a feedback disconnect as well as motor driver error, so if the pot fails or the lever comes loose on the motor connecting to the frame, the jrk senses that and puts a stop to it.
There are a series of errors to enable and latch, just read the manual for the jrk and it tells you which to set.
I have had pots fry and motor driver levers go loose, but I am mad enough never to have bothered with a cut out switch. Still, doesnt hurt to have one in case something goes wrong.
I now have one on mine....must be getting a hint finally...
I use physical stops mainly to stop the frame leaning too far over when I get off it with no power. It tends to roll on my setup. So the levers hit the stops.
Drop us a line as Bob says so we can help set them up.
Bob can try tronics idea with diodes, I am NOT game to try. The jrks work so I leave them at that.
Cheers, David.

[tronicgr]

Bob can try tronics idea with diodes, I am NOT game to try. The jrks work so I leave them at that.

This is not just an idea... It is already being used in a few motion simulators (joyrider type) that I helped with the building process. It works perfectly... I even tried it myself! Here is a tutorial video about it: http://www.youtube.com/watch?v=M6TXQNC1WMY



Thanos

[Riton]

in the past, I tested the switch to stop the engine.
There is a problem with engines very fast, switch off the engine are happening too fast.
The reaction time between the cutoff switch and engine are the switches are overwritten.
With my gear motor, it did not work

[dearn]

Thanks again for your help and information guys

Tomorrow i will start with my router to cut off some wood so the lever can't hit it anymore. Next is to get a emergency switch. I will probably don't use the limit switches at first, i think it will work but it isn't necessary anymore when the lever can make a full turn.

Where can i put the emergency switch between? Directly after the PSU and before the JRK'S as you say BobBuild? I think that thats not a good idea because the high amp. I will prefer to use an illuminated red square pushbutton with a normal switch (NO/ NC function) where i can print the word 'stop sim' on.

About the potentiometer, what would be the best distance to place it? As close or as far from the axcle? I will use the plexiglass method that Floriske and Dave also uses.

Grtz,
Arno

[floriske]

I would place the emergency switch in between the 230V supply (a lot less amps), this way you are sure everything shuts down (for instance when magic white smoke comes from your psu shutting down the power after the psu could render useless).

At this moment I simply have an extension cord with a switch lying near my feet as emergency switch, still need to make myself a decent switch. I'm looking into using a footswitch on my footrest left of the pedals or a button near the wheel.

To be honnest I have no idea if a longer arm is better or a shorter one.

My arms are 20cm long and max distance from the heart of the bolt to the heart of the potmeter is approx. 17cm.
At 9cm up and down travel (max is 10 but I use about 9) this results in 35º angle.
The potmeters are Linear 10K 270º so only 13% of it's range (35K) is used.

I haven no idea how this relates to the JRK feedback range though, I hope BobBuilt or someone else can answer this.

[motiondave]

Bob can try tronics idea with diodes, I am NOT game to try. The jrks work so I leave them at that.

This is not just an idea... It is already being used in a few motion simulators (joyrider type) that I helped with the building process. It works perfectly... I even tried it myself! Here is a tutorial video about it: http://www.youtube.com/watch?v=M6TXQNC1WMY



Thanos

I think the jrks may be internally protected anyway....

[motiondave]

Thanks again for your help and information guys

Tomorrow i will start with my router to cut off some wood so the lever can't hit it anymore. Next is to get a emergency switch. I will probably don't use the limit switches at first, i think it will work but it isn't necessary anymore when the lever can make a full turn.

Where can i put the emergency switch between? Directly after the PSU and before the JRK'S as you say BobBuild? I think that thats not a good idea because the high amp. I will prefer to use an illuminated red square pushbutton with a normal switch (NO/ NC function) where i can print the word 'stop sim' on.

About the potentiometer, what would be the best distance to place it? As close or as far from the axcle? I will use the plexiglass method that Floriske and Dave also uses.

Grtz,
Arno

I put the switch in the power line between psu and jrks. Once the power gets cut, the jrk goes into an error and shuts that part down. Protection. No problem. the switch handles it fine, well....mine does. I bought that one from Jaycar.

Best place for pot is where it is going to give the best feedback, If a closer spot means more feedback depending on lever design, then do that. Experiment.
Thanks, I dont use plexiglass, I just use boring plastic and rough cut. Not as sexy as Floriskes levers.

[dearn]

Finally, an update

Hi all!

Finally, here it is, an update. Today i'm very happy to inform you guys that the sim is working! Today i managed to hook the JRK's to X-Sim, and after a few try's the motors where moving!

But first all the pictures from a few weeks ago

I've routed out some wood so the lever can't hit the base plate anymore:



I made a bracket for the potentiometers and a lever from 5mm plexiglass.


Routed the corners of the wood:


Testing 1..2..3... FITS!


I was reading here that the JRK's need some serious cooling, so I cutted 2 heatsinks and started with a fan housing:


From the garage to a smal room






Fan house allmost done. Also wired up the pots!


Dashboard project is coming...


Electrical stuff finished




I'm sorry for the bad quality pictures. Better ones are coming soon.

The PSU's having a though time. I set the JRK to 30,22A Max current and the other values as follows for testing, and it works great:

PID:
4/4-0/3-1/1 (other values make the motors bounch up and down)

Motors:
PWM Freq: 20mhz (5mhz make the PSU's scream like &%@#)
Max duty cycle: 200 (Right JRK gets an max AMP error all the time if the value is higher then this, left one can go up to 450 without an AMP error, strange eh?)
Max acc: 200
Max current: 30
Current calibration: 124

Now i just have to find the best values for the JRK utility and for X-Sim. But for now its playable. I've just played about 1,5 hours today (fist time) without errors. (if i take a higher duty cycle the right JRK gets an AMP error. The left one even likes 400>, but this one doesn't seem to give an error AT ALL, even when the PSUs are off)

Any tips?

In a few weeks the sim wil be taken apart again to be painted

Grtz,
Arno

Ps. i'm feeling a bit motion sick now haha...

[motiondave]

Nice job there, looks good.
Ok, jrk settings,
try max duty cycle , max accell and max duty cycle while feedback is out of range all at the same number, I see you are you using using 200, set that for all.
Set current calibration at 149.
Set max current at 0 , unlimited.
I have run my jrks at 38 amps with no issues at all.
Try P and I at 4/4 0/3 and test D at 4/4, 3/3. But if 1/1 works stick with it. Leave I at 0/3.
Work with P and D and max accel as above and profiles.
Set feedback out of range at 2, up from 0.

Dunno why one is working different from the other.

Also work with profiles as well to sort motion out.

But most of all....Have fun!
Cheers, David.

[floriske]

Hi Arno,

Looking Good! Looking forward to seeing the first vids

Regarding the PID settings: there is sort of a PID strategy in the user manual of the JRK's (Tuning the PID constants).

My strategy (after getting some advise from BobBuilt) was:

• Start playing with the test plugin to find the value for "P" at which it becomes unstable/overshoots
(Using 1 slider per motor, fastly moving the sliders manually and also setting it to auto at max speed so the sim starts rocking)
• Reduce the max "P" value with 40-50%
• Increase the value for "I" until the "error" is +/-1 and enable reset integral when proportional term exceeds max duty cycle
• Increase the value for "D" to prevent overshooting
• Start testing in game and reduce Max duty cycle etc. to a comfortable feel

The values that came out of that are:

PID: 6/5 - 13/8 - 3/2
PID period: 10ms
Integral limit: 1000
Feedback deadzone: 2

Max duty cycle: 450
Max acc.: 450
Brake duration: 0
Max current: 30A
Max duty cycle while feedback is out of range: 450

And an aditional quote from BobBuilt about PID (contains info about the oscillation):

Heres alittle bit more on PID Tuning,:

“P” and “D” settings generally track each other. If you increase “P” for greater stiffness, an increase in “D” is needed as well to restore critical damping. Be careful, increasing “P” without increasing “D” may cause the motor to break out into violent oscillation.

The higher “P” is set, the noisier the motor will be when stopped. This is because higher gain causes more vigorous dithering between encoder counts at rest. There is a trade-off between high gain (high stiffness) on one hand and excessive dithering (noise and motor heating) on the other.

The “I” setting takes out the remaining following error. Increasing the “I” setting will increase the servo stiffness; if it is increased too much the servo will oscillate

Found on http://www.geckodrive.com/g320x-rev-10.