My 2DOF DIY sim.

Where did you buy those linear bearings and rod? I was looking at something similar for my cnc but they are way out of price... I have followed your thread and i think you are using jrk ( as i do), could you do a screen shot of the graph of the command from the game versus the feedback with the pololu soft? I would love to see the input signal you are generating from you profiles because it looks really smooth. I know this may be a little hard to do if you are running everything from one pc...

keep up the good work

Rails and bearings are fairly expensive, but it's also possible to make some cheaper ones using radial ball bearings and steel profiles.

These are the rails I'm using: http://www.cnc-plus.de/product_info.php ... bf4f923ecf

These are the bearings: http://www.cnc-plus.de/product_info.php ... aeuse.html

The prices are including 19% tax, which is deducted when I order. I'm using eight bearings and eight rails. The bearings are mounted to the structure using simple wire hinges made for small doors. The rails are mounted to aluminum profiles for increased rigidity and to make mounting more practical.

It's hard to make screenshots of the graphs when I'm running the profiler on the same PC as the game. I'll see what I can do. There are PID tricks that I use to make it smooth. If I set up the PID for optimized motor performance, I have great acceleration, short movement time, and stops without overshooting or oscilation, but it's just too brutal for sim use. I lower the P until the sim stops movement smoothly, and D high enough to achieve relatively smooth operation mid-band, but not high enough to cause excessive noise as it's holding a position. Some D-noise is inevitable, it seems. It's always going to be a compromise, it seems, unless I want a brutal simulator, which just isn't fun as it's too jerky. I reduced the acceleration value to ~15 to avoid too sudden acceleration.

I tried shooting the rails but it was a disaster. Too dark. My friend drove slowly, so there wasn't much movement in roll: http://youtu.be/8gm3TloweA8

I'll try again later with another lamp.

looks like you are on the right track with PID, thats one way to get solid motion.
We all set motion to how we like, mine is very solid and jerky, I get a sore back after 30 mins game play (must be getting old) and also every sim needs different configuration of motion and PID.
Sorting, test and re-test, and have fun sometimes.
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I haven't used the sim in a couple of days now. The right screen started losing the signal. It flickered on and off periodically, so I figured the cable was damaged somehow and ordered some new ones. I looked into it today, and the cable for the right screen was squeezed flat in a clamp. Once I freed it from the clamp it worked again. Strange that it didn't happen immediately after clamping it.

I ordered a Thrustmaster TH8RS shifter today. I hope it's good, because it's not cheap. Reviews are positive.

A new tool.

The shifter arrived today. I went outside and measured where the shifter on my car sits, and made an arm with a hard mount for it using my bandsaw and new pillar drill (I gave away my old bench drill yesterday). It's very rigid and won't budge at all . The shifter is a disappointment, though. It doesn't feel anything like shifting a real car, and shifting down from right to left is weird and dirfficult. It's way too smooth to feel realistic, and feels too light. It's sturdy though, and looks like it can take a lot of abuse.

nice looking shifter, start smashing it and you will find out how strong it is ;D

I think that there is a screw for adjusting the shaft strength (I saw it on product presentation video). Maybe you could try to get more feedback with it :?

Yeah, I tightened it as far as it would go yesterday, and it's still a little light to my liking, and I'm worried that it will wear prematurely due to being at the maximum tightness. I'm probably being a little too strict with it though, but I think it's just too smooth. I think the notches are a little too soft. I haven't tried any other PC shifters.

Well, I'm having fun with the shifter today, despite its shortcomings. I keep driving the slow cars in iRacing just so I can use the shifter.

The backlash in the winch gears is getting quite annoying now that the novelty of motion is wearing off. I hope I get some new bearings soon, or maybe I should just design completely new gearboxes altogether. That's probably what I'm going to do eventually anyway.

As for shifter, well, I guess I am lazy and stick with a sequential.
As for backlash in the gears, see how new bearings go. Maybe consider new gearboxes if it works. The winch motor setup may be affected differently in your sim. But dont let it get you down. Goodness knows, most of us have days like that when components do not last or work properly.
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I'm using the paddles on the wheel when I need sequential shifters. I haven't tried converting the shifter to sequential yet. It's too much work for me to bother doing it every time I switch cars.

I downloaded the Lotus 79 in iRacing today, and it's awesome with the H-shifter, but I suck in the fast cars in iRacing. I can win races in the slow cars, but I'm just not Jedi enough to fight the top ten in the high performance cars.

I tried adjusting the rotational center of the pitch axis down to the middle position today, and after a few minutes of driving I adjusted it back up. The rotational movement was too obvious, and the feel of G-force was reduced. For racing, the pitch works best with a very high rotational center (top position), while the roll axis works best with the rotational center right above my head (the middle position).

Oh, and I also looked into installing the pneumatic cylinder. I will probably be able to fit it underneath the pitch axis, mostly hidden from view. The cylinder looks like it's going to work great.

I got the USB isolator today, and it the JRKs still work with it inline before the hub. My PC is safe from whatever spikes the sim will dish out now.

The sim is still jerky during slow movements as it's catching itself in the backlash. I can hardly wait until I get new bearings.

I regret getting these monitors. They are so slow to wake up when they receive a new signal, and will often remain black for minutes after a display mode change, for example when entering a game. They've been like it since new, so it's not vibration induced. It's really annoying. My other monitors come online immediately so I think it's the monitors that are causing it. I should have bought more of the BenQ monitors for the sim as well. Maybe I'll spring for some 27 LCDs when they are on sale, and sell the Iiyama monitors cheap.

Today I experimented with the Analog to digital conversion samples. I used to run 128 samples, and had the PID period set to 4 ms, which was the lowest it will go without exceeding the period. I experimented with setting the Sample rate down to 64, with a PID period of 3 (2 was just on the limit of exceeding). Then I tried 512 samples, and increased the PID to 14. The latter produced noticeably smoother movement, particularly as the movement starts and stops. There is no longer a jerk as I start moving the car, which is logical as it uses more samples to read the feedback.

I also tested different datapacket pause durations. I originally had it at the recommended 33 ms. I tried lowering it to 1 ms just for kicks, and the sim seemes to react more immediately. I noticed a difference when I jerked the throttle on and off. I donT know if there is any point to having it lower than the PID period, so I have set it to 14 ms as well.

I have also settles on a possible final PID setting for racing which is smooth, gets closer to the target, and doesn't overshoot (P: 0,32 I: 0 D: 0,6). I can probably achieve smoother operation in X-plane as well now that I have increased the analog samples to average per PID period.

I got the new bearings I need for the servos in the mail yesterday, so hopefully I'll find the time to make the new parts I need this weekend. I made some pinch hazard warning signs out of plastic this morning. One for each side of the sim above the servo gears.

Well done on PID settings, fiddle with these and you may find a better balance, that and fiddle with profiles. I am still fiddling with these settings :rofl:

Yeah I guess I will always fiddle with the settings, and always question any setting I am using.

I finished modifying one servo now. It's as good as slop free. Before there was 20 mm of slop at the end of the arm I'm using, because the slop in the gear train is amplified by the 270 mm long arm. Now there's about 1 mm of slop in the end of arm. It can't get much better than that without binding. I also made a delrin gear for the second stage, and will test to see how long it lasts. I made an aluminium hub with a clamping mechanism to absorb any play in the shaft intersection.

You can also see in the picture that there is no wear on the first stage delrin gear I made earlier.

I installed the pneumatic cylinder and made some connections to make a working air system. It needs 3 bar to cancel the front heavyness, which translates to 24 kg of force. I have made it so that the cylinder is compressing, so there's no chance of it buckling under the pressure at any time. Cool stuff! It's also air tight. After half an hour the pressure has not dropped at all. I'll leave it pressurized over night.

It works great!

The pitch axis is so much better than the roll axis now. Awesome! The spring is invisible to the movement.