Building a 4DOF from the SK3 kit provided by Simukit

@RiftFlyer you just made it easy for me. I am going do the triple 50' tv instead. When I read the forum there were so many reviews with positive comments about the vr setup which swayed me away from the tv setup which I had in mind originally. I didn't know that vr would have other complications. Thanks!

You can get decent motion cancellation with vive.

@RiftFlyer thank you for that info. I will look into the vive vr.

Now that I have a little more time to play with the sim, I found that it has two kind of major issues which I am not sure how to fix:

1. On start up and shut down of a game, there were a bit of a violent movement in the motors. My guess is that the motors had to move to some initial position but why is it done so violently. It is scary for people who wanted to try it.

2. Since I have mapped the yaw motion to the fourth motor (traction loss motor), it is found that lot of time the sim would yaw to the left or right even though the car that I was driving was constantly moving straight ahead. That is odd.

Would someone know how too fix these problems? I am looking to @jjanu , @Wanegain ,@yobuddy for help here.

Hi @yobuddy,

As far as I can tell, the sim rig started in the position where all the motors are centered as in the attached picture of Simtools game engine output testing. But when the game started the rig would violently snapped to some position that is not necessarily centered. If this can be soften it would help a lot.



My motor on Axis4a is mapped to Yaw motion on DOF 6 of the Simtools game engine axis assignment. You can see that in the attached picture withe the high lighted axis4a. Do you think that my mapping is incorrect?

that was it. Thank you @yobuddy. After I remapped the axis4a motor to Extra1 (traction loss) then both problems disappeared. It was my ignorant as I didnt know what extra1 extra2 and extra3 for so I didnt try to use them.

To make the movement on the sim a little bit less forceful, I also went into the Simtools game manager profile editor and reduce the "Main Level" setting to about 25%. I am not sure if this is the right thing to do but it made the sim a lot more gentle to ride on.

@yobuddy , could you please help me understand the relationship between the "Main Level" setting and the "smoothing filter" in the AxisSetting a little more. For example if I set the MainLevel to x% then how does it translate into how much y% smoothing in the AxisSetting?

Hi @yobuddy,

Thank you for the info.

I found that by reducing the "Main Level" to 25% it helped to make the sim a lot calmer. But at the same time some motion, e.g. heave, was lost on some of the roller coaster ride. So I am trying to see if there is a way that I can leave "Main Level" at 100% and just change the smoothing on the DOF motions to 25% except heave. This is where I am a little uncertain of what to do.

Thank you @noorbeast for your help.

I am very sad to report that my motor on axis1a had died today. This is a motor that I was having problem with from the beginning where sometime it would spin by itself. The motor is set to operate in the forward manner but once in a while it would spin and work in the backward manner. Previously when it spin to the backward position it was able to spin out to the forward position and work again. But this time it stuck there and I didn't know about it until I smell something strange. It turned out that the motor is so hot that it may have burned its internal wiring.

I turned off the rig. Waited for hour for it to cool down and turn it on again. But this time there is no sign of life on the motor.

In the pictures you can see that it had moved to the backward position prior to dying. The second picture show the forward position of a motor at rest.

@Wanegain, would you know if there is some warranty for the motor? Could you help me with this? Thanks.

This is especially unfortunate as I was getting so close with the built and was starting to enjoy riding on the rig.

This motor was one of the odd one from the start. I have tried several things like:

1. Replace the pot
2. Replace the pot wiring
3. Add a few drop of epoxy glue to secure the gear to the motor shaft
4. Tighten the screws on the pot gears

Nothing worked. Once in a while it kept changing from the forward to the backward position.

Now that the sim is all assemble it is going to be a task to remove the motor. Especially in order to access the sabertooth the base of the sim has to be turned upside down in order to get to the motor electrical connection.

@noorbeast @Wanegain , I think I know the reason why the motor was burned:

When the motor got into the backward position and then when it tried to rotate around to the forward, it got stuck because a little bit of the motor shaft was in the way of the U-shape arm that connect the motor to the platform. See picture. The design doesn't allow for a very big gap between the two of them and the production may have a consistency issue where this U shape arm is more closely touching the motor shaft than the other two U shape joints of the rig.


To avoid this problem from happening again I have added several more washers to the connection between the U-shape arm and the crank shaft in order to increase the separation between then. It would be better if simukit can redesign this arrangement to avoid the problem in the future for other users.

I also modified the arduino PID sketch so that it wouldn't send continuous power to any motor for than one minute to avoid the burning of the motor.

Now come the good news: by following @noorbeast 's suggestion, I opened up the motor and saw the problem. It was caused by the carbon brushes burned and stuck inside its housing so they cannot make contact with the motor anymore. I was able to loosen them so that the springs were able to push them out again.

It was not fun to take the motor out to fix the problem. It took me several hours but I am just happy that it is working again.

Hey Stargazer, I'm sorry for not having been able to follow your evolution and answer to your technical problems in the past few days since I'm working full time on an other project not related to motion sim. But reading your latest comments I can see that you've been very busy! I'm glad that you could recover the failing motor on your own and go on with your tests. Congrats. When I'm done with the project I'm actually working on I'll get back to motion sim and prepare a wrap-up report of my built with the SimTools parameters that I fine-tuned for my game list. Many finishing add-ons were brought to my current built and I need to take fresh pictures and make a final video of the whole shebang. Probably in two weeks. Good luck with the rest.

Hi @jjanu
I look forward to read your summary report and new video and pictures of your project. Yours and @axenic 's project have given me the confidence to start this project.

I am in the tuning phase now for the rig and so far I have not settled on any satisfactory profile yet. If you could share yours then that will help me a lot. I want to find the setting where it gives a good sense of motion minus some of the crazy jerky movement that is scary to the rider.

Ttya

The problem of axis1a motor sometime went crazy and spinning by itself have frustrated me to no end. I replaced the pot wiring connection the second time, checking carefully for cold soldering and that didn't help.

So I decided to do an experiment with the help of simtools output testing. The procedure is like this:

1. Put the rig in idle position where all output levels are mapped to zero. Use a bubble ruler to check that the rig is perfectly level. See picture.

2. Move the axis1a output level to the extreme 100 or -100. Then clear ('CLR') it back to zero.
3. Repeat 2. A few dozen times.
4. The result is that the motor's idle position kept on lowering after every 2. And eventually it is so low (see picture) that an extreme -100 level would cause it to go backward and start spinning. Which was exactly the problem I got during playing with the rig.


The interesting thing was that if I went into 'Axis setting' and limit the output level for axis1a to 85% from 100% then the problem went away. I can execute 2. As many times as I want and the rig's idle position remain perfectly level.

Anyone want to take a guess if this is a hardware or a software issue? @Wanegain , @yobuddy have you some idea?

Since the problem went away by a change in software setting I am incline to think that it might be a software issue but I cannot be very sure.