Design Advice

depends on the design of the sim.
Seat mover total height to top of the bottom cushion can be about 400mm http://www.xsimulator.net/community/threads/desk-racer-2dof.5326/ to reach a desk , so pivot was 220mm long, or like a more traditional seat mover http://www.xsimulator.net/community/threads/eao-robbies-static-sim-to-seat-mover-conversion.4650/ where the pivot is shorter, about 130mm I think on this one.
19 inches is 470mm , thats fairly high but will work with shoulder mounts.

Moving wheel and pedals back towards driver , especially if they are lighter doesnt affect a full frame 2DOF balance much. I know this from my foot motor mount sim. Even though the pedals simply were dragged back towards the shorter driver.
As suggested by @eaorobbie , I did that with 2 of my current sims, they adjust from driver 1.9m to driver 1.4 m. A wheel stand with a set of draw rails.
Wheel mount is height adjustable

I move the bolt hole alignment to the shorter driver. Simple, but it works.

Not to flood your post, this is my example and you can see the base of the chair is only 202mm (8") off the ground. Now that can be raised , noted on the drawing as long as you keep 'A' (distance from the centre of the uni to the base of the chair) under 100mm , closer to the base of the chair the better. What happens as you increase 'A' it exponentially increases the mass once in motion. So to help the DC motors achieve their fastest speeds for real good road vibrations and ultra quick changes of direction keep the centre of the uni as close to the base of the chair, meaning if your height to the chair base is 19" make sure the uni's centre is no further than 100mm (4") away from the chair base. And I can not see an issue.
Plus it needs to be under the cg of the whole mass not the actual measured centre, so that the weight is spread evenly over the pivot.

Hope that helps.

@eaorobbie - Your drawing is one of the items I have been referring to. So, as long as "A" stays under 100mm, the only change would be the needed length of the rods connecting the seat back and levers. As long as they are beefy enough, the length is not a concern?

On a different note - I have finally started receiving components. I can now start modifying my power supplies!

I read that the Jrks allow for several different attachment methods. The blue blocks just get soldered into position?

I envision some late nights coming up.

Progress!!! I have converted my server power supplies and all tested around 12.5V. I added an on/off switch as well as the fan mod. so it would not be so loud. I have not decided how I will connect from the spades though.

I do have a quick question for anyone else who has done this modification. When I tested after I connected the required pins, I just touched 1 ground spade and one + spade and my multimeter read 12.5V. I was under the impression I had to connect both ground spades together and both + spades together, but my power supplies tested at the correct voltage as is (not connected). Did I misread the procedure or do I need to connect the spades to gain the full capabilities of the supply?

Steve

I have been building away and had a huge "Oh #$#$" last night. I have my base built and I have my traction loss platform mounted and ready. During all of this building, I planned to use a used office chair to cut down on $$, so all of my dimensions were with this chair in mind.

Mounted the chair on the UNI and needed to adjust one of the brackets and ... wait for it ... I broke a bolt off in the chair!! UGH!!

In a shocked daze, I stopped by the local farm store and found a tractor seat that came with a steel frame. All I had to do was drill a few holes and I had the new seat mounted and ready.

Now come the problems/questions. I apologize now for no pics, but I will get some tomorrow.

This is what I have:

Mounting width at seat back - 9 inches (this seat does not have a high back, so attachment points are approx. armpit height or a little lower.
Mounting height: approx. 17 inches above UNI.

Motor Positions: I currently have the motors sitting at ~ 7 inches back and ~7 inches out from the seat back points. Motors are mounted square to the base.

Current Rods: approx. 21 inches long.
Levers: approx. 3" CTC, from .125" steel.

I bolted everything up and played around with someone sitting in the seat, while I manually moved the rods.

It seems like one of my rods is binding up - as if my pivots need more range.
The "left"/"right" movement is very good (maybe too much), but the leaning forward/backward was minimal.
The .125 inch lever on one of the motors is bending (the side that seems to be binding up).

So, now my questions.
1. Do I have my motors to far out? I thought I had read somewhere 8" back and 8" out, but I could be wrong.
2. Is .125" typically thick enough for a lever? Is mine bending because of poor motor placement?
3. If I want more movement/rocking forward and backward, I am thinking of increasing my lever length. But if I bring the motors in some, it may help that issue - even using my current levers.
4. What is the typical lever travel for a seat mover? 90 degrees? I have 270 degree pots, but I do not remember how much of that is actually used. I plan to start playing with the software tomorrow so that may become more clear then.

I will be mounting my pots tomorrow and hopefully some of you experts can help troubleshoot my issues.

I really appreciate all of your help.
Steve

might need to see some photos....

I changed my attachment bolts at all four pivots and everything moves very smooth now. I also beefed up my levers to boot.

I am now wiring the pots and Jrks, so I should have some movement soon! I have loaded the Jrk utility and SimTools on my laptop so I will use that to work through the setup/bugs.

I am not going to lie, I am nervous about smoking one of my Jrks before I even get to the fun stuff!

Don't be nervous just be careful.

1. Make sure there is no body ground within the wipers or big worm gears, sorry forgot which you are using.
2. Wire the power correctly on the Jrk , A big must (about the only way to smoke one)
Vin is +ve 12v GND is the earth, Motor can be wired either way on A & B you can always invert the signal
In the jrks configure if need to reverse the direction on the motor.
3. Wire the pot correctly , Jrk 5v to positive side of pot, Jrk GND to negative side of pot, Jrk FB to the wiper
on the pot (in most cases the middle pin.

Setup the motors in the Jrk Config Utility first then they will be ready for SimTools without giving you any problems.

Have fun and enjoy.

@eaorobbie - I looked on the pot data sheet and I could not see a specific + and ground assignment, but the middle pin is def. the FB.

I thought I read on a thread that the 2 outside pins could be set up as either + or ground, as long as the FB pin is correct. Is that correct?

does this assist?

I lost a day of progress because someone gave me a seat that was MUCH better than what I had. It was worth the extra time to get it ready to use.

I have set up both Jrks with the Jrk utility. I followed @eaorobbie 's instruction exactly. The first Jrk seems really good. The second Jrk seems to be overshooting the target by quite a bit, but it looks like only when it travels a large distance. I can use the slider function to move small increments either direction with no issue, but the bigger movements have the overshooting problem. But, the lever does eventually end up at the correct spot.

My design has a hard stop on the downward travel and my current "learned" position for the minimum position is very close to the hard stop. So, any over travel causes the lever to crash into the hard stop.

Suggestions?

Thanks.

screen shots of PID and motor tab please

@bsft - I am not sure how to do screen shots. I will try to take a pic with my iPad and see if it turns out.

Also, if I just open both tabs and get pics will that work? Or do I need to send a certain command first for you to see what your looking for?

Thanks for your quick response.

yep, that should do as long as I can see the tabs on the screen

Hopefully these pic work. The tab pics are from the "left" Jrk. After I took the pics, I was planning to use the slider to reposition the lever so I could get a few plots as well. The lever went bonkers and started pounding on the hard stop. Before I could power down the motor, I managed to relieve the pot of its magic smoke. Luckily I ordered several extra.

I then went to the "right" Jrk to have another look. The 2 plots are from the right side and show the same over shoot I had noticed on the left. I guess I didn't cycle it as much the first time so I didn't notice it.

So, I am wondering/thinking that my settings(same for both sides) may be causing the over shoot issue AND my left pot may have been a bit whacked from the start (pounding hard over and over on hard stop/frame.

Sorry for the rambling. Obviously, I welcome any and all advice.

Thanks,
Steve

set max current at 0 , unlimited , try bringing D up from 0.5 in steps to 0.9
Drop max accell down to 450.
Max duty to 350
if motors are slow, speed them up in steps on 25.
Give that a run.
sometimes it requires individual PID and motor settings. I found that recently with my red "desk racer" . I have to do individual settings.

@CoachKalk , you also need to test the motors under weight to see if they still overshoot.
Even Ard sims overshoot without weight on them.

@bsft - thank you so much for the suggestions. I had great visions of hammering this out today, but these darn family responsibilities keep popping up. What I thought would be an easy brake job on the kids' car turned into 2 stuck calipers. Ugh!

After that mess, I started my fun stuff. I finished attaching the new seat. I was actually able to attach higher than I thought, so that is 1 good thing.

I wired up a new pot and decided to use the 2 hose clamp method. I may be wrong, but this seems like a better way for those of us without precise methods of drilling the center of the motor shaft bolt.

I started the Jrk setup again ... And quickly figured out I had a big problem. It looks like my Jrk went up to the big Jrk heaven in the sky. It looks like the pin in the FB position was not soldered well enough and the pin "fell" into the +v pin. I tried to solder a new pin in the AUX spot, but the Jrk will not register the voltage change when I turn the pot. I tested the pot with my multimeter and it was working fine. When I would "learn" the max and min, the values would come back the same.

Would it be worth a try to add pins on the other grd and +v spots or has the damage been done?

I had a third Jrk ready for my traction loss, so I wired it up. Success. I was able to have both motors running at the same time. I sat in the seat and moved it around a bit. I didn't go to the extremes, but it seemed to respond very quickly - maybe too quick. I will try the suggestions given as well.

Does SimTools allow for finer adjustments? I am not sure what/when I am ready to move on to SimTools.

Thanks,
Steve

I will tag @eaorobbie to advise alternate wiring of the JRK.
Simtools does have adjustments for motion to make it finer and less nasty, however, if you can settle the motors a bit first in utility, that will help.
As for clamping pots to motors, good idea with hose clamps.
Probably because I have a drill press, I now only drill and tap a 3mm bolt through the "top" of the back of the bolt, drill out the back of the bolt for the pot shaft to fit into, and I use the 3mm bolt to hold the pot steady. I dont bother drilling right through anymore.