Showroom 2 DoF platform using wiper motors

Hello, I would like to do a little show and tell about my 2 DoF motion platform. It’s nothing revolutionary by any means, however this is not my first simulator and I would like to give some advice for people trying to make one on their own. I’ll include some photos of the finished build in the attachments. Here is a video of the simulator:

A few words of advice:

I made my platform a bit too heavy, and while it is stable when someone sits on it, the single beam to which the gear shift lever and steering wheel is attached to makes it prone to leaning on that one side. A counterweight was planned to be added inside the steel tube profile, however in tests the windshield wiper motors are strong enough to stabilize the platform.

Another thing I added to counteract the weight of the platform are two gas springs, 200 [N] each. This is a bit too much and 100 [N] would be enough in my opinion. They also slow down the movement of the platform a bit. I’ve done tests without them and the work fine, however when I power down the simulator without these springs, the upper platform cant stay in its position.

The wiper motors themselves are from a front windshield wiper mechanism from a Opel Corsa. They are quite powerful for their size, although I hade two problems with them. First of all, the mounting system for the lever. At first I just drilled a 8 [mm] hole through a piece of flat bar and another 12mm hole going just 2-3 [mm] deep. My technique was to tighten this lever with a M8 nut tight enough to bite and create grooves from its knurled tapered shaft. It did not last long until it got loose and fell off. I hade to grind a drill bit to fit the ~10 [deg] taper of the shaft and then it drill the lever arm again for it to bite enough to stay in place. Also used two part epoxy to secure the nut so it wouldn’t back off. Another problem was heat. I quickly remedied this by drilling a few vent holes in the body of the wiper motors. Originally I planned to add a small fan to force air and cool the wiper motors. I didn’t do this due to it not generating that much heat with just a few holes drilled out. My guess is the rotor spins fast enough to force some air movement and get rid of its heat.

For feedback I used DIY hall effect potentiometers. I wanted them to be serviceable and adjustable so no glue is used. You can also easily take out the magnets. They work surprisingly well, however it is crucial for the hall effect sensors to be exactly in the center of the axis of rotation and the magnets to be adequately spaced apart. I say adequately, because adjusting these takes some trial and error. First you have to set the depth of the sensor, then the depth of the magnets and finally make them symmetrical to the other side of the platform. For the future to save some headache I would like to experiment with magnetic encoders.

The universal joint was made out of four UCP 204 bearing blocks. This is a fairly decent solution and cost effective, if you have enough space. For saving a few centimeters in diameter I had to make the two axis of rotation offset from one another. This would not work as a regular U-joint, however in this application this distance is not noticeable. Additionally, the ease of maintenance and serviceability is far superior than in automotive U-joints.

I get a lot of questions about the seat. I made it for a buggy project, which in the end didn’t make it and had two of these seats left over. One I used for my 6 DoF rig in Uni and the other I’m using here. Overall I guess it fits the general aesthetics of the motion platform. I tried sitting in some cheap bucket seats and they were ok, however in my opinion they were a bit too tight for some leisurely gaming.

Feel free to ask questions .

It looks neat, do you have any video of the ride ?
If you can show your 6DOF project

As far as the 6 DoF project goes I have yet to make a thread about it with pictures and videos. When I'll have some free time I'll create one next week. As of now here is a little sneak peak of how it looks .

Looks good and very compact. Do you have any issues with weight on the right side (since it is holding the support bar for all you peripherals)?

For mine I had to add struts to keep weight on the motors and to "help" my left side (most components are mounted on my left side for air sims) motor carry the weight.

Note: I think I messed up my center of balance also slightly (first time doing it so next time will be better).

Thank you, yes there are some problems with weight being on one side. I added struts which help a bit. In practice the motors level the platform when its turned on. I played Dirt Rally 2 for almost a hour and the only side effect I can notice is that the righthand motor is a bit hotter than the left one.

Good information. I didn't even think of checking if my motor on the left is hotter after using them for a while. I'll check and give feedback this weekend (hopefully).

Ya, my left motor is hotter after a couple of hours of playing. It's not horrible but I don't think I'd do more than a couple hours of gaming at a time. Is there any recommendations from the community on gaming time? or possibly I could set something up differently to make it easier on the motors?

Note:

• I use the recommended 10K potentiometers but it does sound like the motors are always "running" even when the simulator is just at the 'rest' position.
• When I cut power to the system the motors usually "rest" at the lowest point they can go with the weight on them. I.e. "down"

Well you could try and balance your rig again so that it stays level with you sitting in it. However without redesigning your sim I would suggest drilling some vent holes in the motors housing and/or using a fan to cool down the motors.

I use hall sensors and they do the same. You can adjust the deadzone in SMC3 if your using it. I just think its normal and wouldn't worry too much about it.

In my case when I power down my rig the upper frame shoots up a bit. However when im sitting on it and power it down it stays somewhat in place. So much so I could use it a sationary rig. Maybe use some bigger gas springs or add a counterweight?

Thanks for the info. I'm not confident enough with my knowledge of motors to drill holes in them but I'm thinking some heat sinks (like on wood stoves and CPUs) with fans would allow the heat to dissipate faster. Once I try I'll post what I find.

Sure, good idea. Before drilling out my motor housing I tried searching for dedicated motor heatsinks like for rc cars, however I couldn't find one with the right diameter.

The problem with DC motors is that the windings are on the rotor. So adding heatsinks to the housing does not really work well. When the motor spins at nominal speed (~3000RPM) the circulating air around the rotor leads to good cooling but in a motion rig the motor runs at zero or low speed most of the time. So a forced cooling only works if the air goes through the inner components. Blowing air through tiny holes takes a relatively high pressure and thus high RPM of the fan. So buying larger motors in probably the better option.

I would buy bigger motors but where I live the cost jumps considerably to go to the "next larger" motor. I.e. wiper motors $110, heavy duty tarp motor $350 - $400. So I could burn out 3-4 motors before it would make sense. Every time I read of someone in the US find a old motor with TONs of power for $50-$75 I get very envious.

Note: I am considering the exchange rate.

Agreed, spending >$300 for DC motors makes no sense. You can get industrial AC servos with driver for less than $200 (Example on Ali). These motors with integrated drivers plus gearbox would also be an option. Also well below $200.