Kartsim 2dof seat mover

I had posted this previously but accidentally deleted the entire thread when I was just trying to delete one post so here it is again. Basically I used a kart seat and wiper motors for my rig. I didn't use a frame for my seat rather I just epoxy the seat directly to the universal joint and bolted the struts directly to the side of the fiberglass seat to save weight. It's really lightweight and it works well, it's been over a year now and it's held up perfectly without any issues.

I already have all the parts to add the traction loss just need to find the time to put it all together. I will post pictures of the traction loss as I go. Thank you to all the members of this community for your help with this project. Please feel free to reach out to me for help with your project I'll be happy to help if I can.

Here is a sketch of my original idea, this was before I change my mind and decided to use a kart seat. I have to say that I do very much like the kart seat but one drawback is it's not so great for having others try the rig. Kart seats are not one-size-fits-all so some bigger people definitely won't fit. If you know you're going to want to let different people try your rig you're probably going to want the traditional car seat.

I chose to use wood for the base just because I'm not the best at welding, I had a friend help me with the welding that needed to be done. I'm better with woods so I chose to use wood just so I could do more of it myself.

The universal joint I used is from a steering column or steering shaft that I got from the wrecker. As you can see I cleaned it up and welded a plate on either end.


The kart seat is made of fiberglass and has a flat bottom. Those of you familiar with karting will know the flat bottom enables the seat to be mounted lower in the go-kart lowering the center of gravity enabling you to go quicker around corners. I utilized the flat bottom to epoxy the base of the U joint to the seat. I made an epoxy bed and it's stuck like crazy to that thing. These seats can be fairly expensive, this one is over $300 new however I picked it up lightly used for 40 bucks.

I used wiper motors just because they are cheap and I was building this a budget. And by cheap I mean free, my father-in-law is in the automotive business and has a bunch of salvage cars so I pulled these out of a Dodge Journey. Of course I also had to do the ungrounding as with all wiper motors, I didn't take any pictures of that process but it wasn't very hard. One thing worth noting if you're planning to use wiper motors is you want the original leaver that's connected to the wiper motor. With one of my motors I didn't get the leaver so I made one out of steel but eventually it started to wear the little gear at the end of the shaft so I had to go to the wrecker to find a car with the exact wiper motor and get that lever.


The bracket for the motor was pretty easy to make, just used some more of the same steel from the U-joint plate. The hardest part was Drilling the big hole for the motor shaft. I had to use a bi-metal hole saw. You have to keep spraying WD-40 or some type of lubricant to keep it cool while you're drilling.

In the first picture you can see that I used a piece of hose to connect the shaft to the potentiometer however I had to switch that out for a better solution after a while because overtime the the rubber hose starts to lose it stiffness and you get some slop between the motor shaft and the potentiometer. I picked up some of the fancy flexible couplers from eBay for really cheap. Haven't had any problem since I switched them out.

The potentiometers are 10K ohm linear pots from my local electronics supply shop. Super cheap, but I haven't had any issues with them so far. If you don't want to spend money on wire, find some old telephone cord strip back the sheathing and the individual wires inside work great.

I had to weld metal to the levers to extend them because I figured the original was too short. So I made them extra long to begin with so I would have the option of cutting them down to any length. You can see the weld where it was extended and the felt marker where I was thinking to cut them to. In the end I left them a bit long (85mm) cause I always have the option of drilling holes further back. After setting up the rig and going through the tuning I've now decided that the leavers are a bit long and am considering shortening. The movement is super fast and snappy and the motors handle the load easily but I just don't need that much travel.

One of the things I had to do that was unexpected, or at least I didn't think about it at first was find spacers or bushings to go between the tie rod end and the nut and lever. You need to do this otherwise the rod end hits against the lever or the nut it doesn't give you enough angle. I tried a couple different things but in the end I found a Metric bushing at Lowe's which I cut into four pieces and used between the nut and the rod end. I'm sure there's lots of other ways to accomplish this but this is just what worked for me.

I'll talk a little bit about the electronics side of this project. I chose Arduino with Monster moto controller, again this is because of the budget, these boards are available on eBay very cheap and I didn't mind having to do a little extra programming or whatever was involved getting it to work. At the time of writing this I've already had this running for the better part of a year and I've formed a bit of my own opinion based on my early experience and some changes that I've made already.

Initially I was very confused about how to wire everything up. There is so much information available on this forum and so many different wiring diagrams it's easy to get confused. So I'll try to clear things up hopefully this will help someone looking to do build one of these things. I'm not going to give detailed instructions on how to do everything here, just basic steps and clarification on a couple of things that I found confusing. Basically, you have to program your Arduino with a code in order to use it with Sim tools. There are different codes you can use and each code has a different wiring.

Initially I was using the code by Racingmat but I have since switched to the SMC3 code. The reason I switched was just to try something different but it turned out to be night and day for me. I was never really happy with the movement of the rig on the first code, it was jerky in one direction and smooth or smoother in the other. So much so, I had to physically flip one of my motors so that they would both be smooth in the same direction and jerky in the other direction. That way it was jerky under braking and smooth on acceleration, I could manage it best like that so that's what I did. I'm pretty sure there was another way I could have accomplish this without flipping the motor but at the time I didn't have much experience and I wasn't exactly sure so I just flipped it.

Anyhow, that's all in the past now. The SMC3 is smooth in both directions. I'm not trying to say that one code is better than another, it's just my experience and of course it's based on my rig with my setup and settings. By the way, I didn't have any experience with Arduino or programming code or anything like that before starting this project so it was all very new to me but to be honest it wasn't that difficult. One thing that helped me was that I had built a small working 2dof model before I started this so I knew what to expect when I got going on the full size rig.

Code:

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The first step was to install your Arduino. Plug your Arduino into your computer USB port and install the driver and the Arduino software which you get from the Arduino website. Then once it's installed and you can communicate with it.

Next, download the code from the FAQ under the Arduino section. Unzip it and upload it to the Arduino. https://www.xsimulator.net/communit...3dof-motor-driver-and-windows-utilities.4957/

Follow the instructions on the first post of the SMC3 page and connect the wiring from your pots, motors, Arduino, monster moto, etc. The instructions are pretty good, you should be able to get it working.

This is by no means a tutorial or complete instructions, just a basic recap of my experience with this build.

I realized very quickly that I would need some Cooling for the chip on the motor controller. I saw some heat sinks on eBay for super cheap but I didn't want to wait, I needed something now. I found amongst my collection of nearly useless computer parts and junk an old video card with a heat sink which I removed and cut to fit. I drilled a couple holes so I could see the direction lights and stuck it on with some thermal paste that I got from a local computer parts store. Eventually I will get an nice box to mount these boards in but for now I just left them sitting there.

I'm having a problem of one motor cutting out after a bit of use. All I do to restart it is shift my body weight in the seat to get it back up and it starts working again. Might be a coincidence but this only started happening since I switched to the SMC3. Another thing I should mention is that from the time I built the rig this motor always gets way hotter than the other one but it has never cutout like this before this week. Anyone have any ideas why this is happening before I pull it apart?

Getting really close to testing the traction loss now. The rig has been apart so long that I have to now update to Simtools 2.0. Did some painting as well.

Still waiting on 1 monster moto from ebay but other than that it's just about ready. My original plan was to keep the third motor mounted on the platform so I could enclose it but I thought this would be easier to test and get it all working first and then I can improve on it later if I decide.

Managed to locate a matching third motor from the local scrap yard. Luckily Dodge uses these Bosch motors in many of their late model cars. This one is out of a Dodge Avenger. By the way I highly recommend these for wiper setups. I had some other motors from some Japanese model cars and they were no where near as powerful.

I'm still having a problem of motor(s) stopping during use. I thought it was just one motor but it happened with both last night. I'm thinking nit has to do with the Max Limit or Clip Input settings in the SMC3 code cause it happens once the rig really starts moving and as soon as turn it off and back on its good again. Anyone else have experience with this?

This is the first I'm seeing of your thread, otherwise I would have replied sooner. I had a similar issue and made a code change to SMC3 to resolve it by issuing the monster moto reset command every X ticks. You can see my post on it here: https://www.xsimulator.net/communit...-ricmotech-rs1-clone.10377/page-6#post-143652



Also, that lever on the traction loss motor looks HUGE, is the wiper motor going to be able to provide the torque needed for moving the platform with a lever that long? I have a spare wiper motor laying around that I'm thinking about using to add traction loss but I'm concerned it won't have the torque needed even with a shorter lever than you have installed.

Thanks for your reply. Reset command is definitely one way to solve the problem but I really would like to see if I can get to the bottom of why it's shutting down first. Did you ever look into the Max Limit ?

I was reading a little further down on your Thread and noticed the posts about motor noise. My Motors are extremely noisy and I would love to know how to quiet them down and make them run smoother as you have done.

As for the lever length on my traction loss, I haven't been able to fully test it because I am waiting for one more motor controller to arrive. I did do a quick test with the One controller that I have and it seemed to push it fairly well but I didn't run it for too long so I'll know more when the new controller arrives.

I ended up being happy with the reset command since it fixed the issue without being noticeable even in the slightest.
The Max Limit setting in the SMC3 utility probably isn't the issue unless you are over-rotating your motors, which would definitely cause them to shutoff to protect your rig.
The shutoff issue I had was most common when the motor was aggressively changing directions, like during shifting with hard acceleration.
You can see it shut off around 20 seconds in on this video



Can you post a video of your motor noise?
If it's the same that I was experiencing then it's a simple software fix to smooth your potentiometer values OR an even easier hardware fix with the 104 ceramic capacitor like I ended up doing later on.
I can walk you through either fix if you decide that's what you want to do.

Above is the video showing the noise and the motor stopping repeatedly. Let me know what you think, the noise doesn't really bother me to be honest cuz once I put my headset on I don't hear it but I would definitely be interested in having it smoother Etc.

As you can see the motor stopping is a huge issue.

I really would like to change some settings using the SMC3 utility but I'm not sure how to do it. I put my arduino com port in the ini file and opened it up but it didn't seem too let me change any of the settings. Can anyone tell me how the utility works? Thanks

Looks like the same shutoff issue I had, I spent a while trying to track it down and ended up just making the reset code change to the SMC3 code. Someone more knowledgeable can speak to a possible actual cause
As for the noise, it doesn't sound nearly as loud as mine did, but it does sound a bit like it is caused from noise in the potentiometer feedback. The 104 0.1μF ceramic capacitor bridged from signal to ground on the pots would probably help, they are super cheap to try if you have an electronics shop near you.

When you open the SMC3 utility what happens? Does it say "please wait, establishing connection"? or are you shown a line graph?