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Showroom Compact seat mover using wiper motors

Discussion in 'DIY Motion Simulator Projects' started by Otso, May 13, 2019.

  1. Otso

    Otso New Member Gold Contributor

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    In April 2019 I started building a compact seat mover using wiper motors. I ordered four motors for 25-30€ each from demolished cars (Toyota HiAces). At the time I didn't know if I would make a seat mover or a g-seat so I purchased four just to be sure and they happened to have four of the same model. For some reason they only sent me three.

    I decided to convert my GT Omega Art Racing cockpit to a compact seat mover.

    I wanted to keep it as simple as possible so that there would be any chance of completing it. Another reason to keep it simple was I wasn't sure how much the motors would handle, although in my initial tests they seemed surprisingly powerful.

    Now I started looking for a universal joint. I ended up ordering a front steering bar with a u-joint from a demolished Honda Civic (25€) from the same place as the motors. I could have saved a few euros in shipping costs by ordering it all at the same time.

    I purchased a 30 x 30 x 1,5 mm square metal bar, a 30 x 30 x 3 mm L-formed bar, and some other small stuff. I inherited a welding machine and tried welding a few strips on a scrap metal piece, and then went straight on to weld directly on the seat mover... which can be seen in my "high quality" welds. :) But they seem strong enough.

    Attaching the lever arms to the motors was probably the trickiest part. Here a metal lathe would have come in handy. I manged to make a suitable pipe from a 16 mm circular metal bar with my drill press. In one end the hole is 12 mm wide to go around the motor's axle, in the center 8mm for the axle threading and then a 6,5mm hole for the pots in the other end. Or actually, I had ordered the Hall effect sensor that seems to be popular here. In the lever arm I made holes for the bars that attach to the seat at 40 mm and 60 mm. The lever attaches to the motor with threads, but that of course is not enough to prevent it from slipping. I tried putting three evenly spaced screws from the side pushing into the grooves of the wiper motor axle. As I suspected, it would still slip. I then tried making deeper grooves, but they had too much play. I finally ended up cutting up slots in the pipe I had made and welding it onto to motor.

    Another surprisingly tricky part was removing the current flow from the motor shields. I first thought I would just have to cut of a cable to the shield, but it turned out that the current only flowed through the shield (the positive on the inside on a connector, and the negative through the shield to another connector). So I had to do more rewiring of the motors than expected, and spent several hours on it. I might add more details and pictures later.

    For the motor driver I wanted to use a Sabertooth 2x32, but they were out of stock and new ones would not arrive for a few weeks. In the mean time I borrowed two home made Simple-H H-bridges so I could start testing using SMC3 on an Arduino.

    My initial plan was to use some old PC power supplies that I had lying around. I did a few tests. Under heavy load the PSU I used shut down, even though the specification was 24A at 12V, and I'm quite sure the motor didn't use that much. (My Fluke meter is fused at 10A, so I couldn't measure the current, which I know exceeded 10A). I then connected the motors to a 7,2 Ah lead acid battery I had, which worked good. I later switched to a 18 Ah battery, even though the voltage never dropped below 12V on the 7,2 Ah battery even after playing for an hour or so.

    After assembly of my rig to the point that it was usable I naturally tested it out (using the holes at 60 mm). And, wow, was it powerful! I would never had expected to get so much power out of wiper motors. It could throw me out of the seat sideways. Using the motors with full power and full motion is too much. Reading the forums people seem to underestimate the power of wiper motors. Yes, I am lightweight at about 65 kg + the seat 16 kg and the rest of the rig maybe 5 kg, say 90 kg in total, but still. I am sure it could very well handle a 80 kg or heavier person.

    I just tried hanging on the back of the seat with all my weight, and the motors were able to hold. I didn't try any movement, though.

    The seat tilts about 10° forward and backward and to the sides when I use about 90° of the motor range.

    The first game I tried was NoLimits roller coster, because I though that would be a good test with slow and clear movements without any needs to control it. After that I went on to Asetto Corsa. After that to Dirt Rally, which immediately became my favorite game. I had previously only tried it about once in VR (on the static rig), but didn't like it because all the jumps and bumps in the driving felt stupid when you were sitting in place and gave me motion sickness. But in VR with the seat mover, it is just awesome! It exceeded my expectations (especially given the wiper motors) by far. Next up was DCS, which I only briefly tested because I haven' t yet mounted the joystick and throttle to the seat. For driving having the steering wheel static is ok (or good), but for flying I want to have the joystick on the seat.

    I've still got some finalization to do on my rig, like painting, making the parts look better, better cabling, the joystick mount etc. I will also mount the Hall sensors on the outside. I 3D printed flexible joints for that and they seem to work good. I have some other stuff yet undone before I can mount the sensors on the outside.

    Here are some (just slightly dated) pictures. I'll add more recent ones later.


    20190505T115143.jpg 20190505T115553.jpg 20190505T120016.jpg 20190505T115205.jpg 20190505T115332.jpg 20190505T115354.jpg 20190505T115443.jpg
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    Last edited: May 14, 2019
  2. gingercat

    gingercat New Member

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    My Motion Simulator:
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    Look forward to seeing some videos of it in action!
    You might want to reconsider the mounting of your hall sensor - if it is physically possible for the motor to spin 360 degrees, at some point, it likely will (because sh1t happens), and it'll trash your sensor when it hits the metal strip you've mounted it to.
  3. Otso

    Otso New Member Gold Contributor

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    Hi, yes, you didn't read my entire post, which admittedly was quite long ;-).
    Here's a video when I test with Dirt Rally. I have not yet had time to make a video where you can see the game at the same time. Might add that later. In the video below there is some squeaking from the left side of the platform, that normally isn't there. I will investigate and fix it as it is quite annoying. Otherwise the whole setup is quite quiet.

    It would be ideal to have the platform bolted to the floor, as it jumps around a bit, making some noise, but that wouldn't be practical. Will consider adding some weight to the bottom.
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    Last edited: May 18, 2019
  4. gingercat

    gingercat New Member

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    D'oh - yup, I did read the whole post, but then my fish brain forgot the details when I then looked at the photos :)
    Great vid - seems to work pretty well! Those motors are much quieter than the golf wiper motors I've got!
  5. Otso

    Otso New Member Gold Contributor

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    I've now got four more identical, or nearly identical, wiper motors as I'm now convinced they are powerful enough to move a small 6 dof platform, especially if I add springs or gas struts to keep the platform centered at rest. I will however not start building anything for months, as I've got quite a lot of other more important real life things that I have to get done. (Although, I can't really think of anything more important than using my platform and improving it. ;-) ) I might also consider to initially just add two motors in the front and make the center joint slide vertically to make a small D-box type of thing to add heave. Adding traction loss would be a higher priority for driving games, but my main focus might be flight sims (especially DCS).

    My next near future step will be to add a modular attachment system so that I can mount a joystick and throttle and maybe pedals.
  6. Otso

    Otso New Member Gold Contributor

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    The motors can get pretty hot. I feel that sometimes they get hotter much quicker than other times even though they are not doing much work, even idling. It can be because I have been playing with the SMC3 settings that cause differences in how fast they heat (which would be natural), but I'm not sure. I'll experiment some more. Here's a thermal image after playing Assetto Corsa for a while. I don't know how long I played, but I'm quite sure it was less than 30 minutes. I have been playing Dirt Rally for longer without the motors getting that hot. I haven't measured, but based on hand feel.

    The hotspot in the image below is 77°C.
    motor_temp.png
    The other motor was significantly cooler, with a hotspot temperature of 55°C.
    left_motor_temp.png
    The electronics do not get hot. The hotest spot on the Sabertooth is 30°C. We had a hot day today (and no A/C), so the ambient temperature was pretty high, maybe around 24°C (which can also be seen as the coldest spots in the images).
    electronics_temp.png
    Last edited: May 19, 2019