M4 Motion Theatre given new life Kangaroo2 and Sabertooth

Hi everyone,
My background is in Computers, telecommunications and electronics , I am rebuilding an old M4 motion theatre for a client, after a few tests and a bit of reading on what hardware was available to connect to Simtools we decided to use the kangaroo2 and sabertooth motor driver from dimensional engineering, so I will show the build as we go , plans involve complete new video system removing the composite video projector and replacing with an UHD 50inch screen and perhaps incorporation of oculus rift.
The old system runs a fairly old computer syncs with a Laser Disk player and plays a few different simulated rides, for those who don't know what a M4 Motion Theatre is there are a few videos on youtube and I will be posting some photos and videos as interest demands, they are basically a commercial product used for an amusement ride , I believe there are a few of these machines in the USA but only a couple in Australia.

We had a lot of trouble finding any specifications for the hardware such as details on the motors so that was the first hurdle, the motors have no branding or specs on them but I have found specs for the encoders so that looks to be sorted we will see how the kangaroo2 goes when its all wired up.

Have not had any experience using the simtools package so as the project develops I am sure this forum will be a valuable resource.

I have a 60 Amp 30V DC Test bench supply that I am using at the moment but I am looking for a power supply that i can build into a rack mount box of a similar or higher specification as the amps load on the motors max out at 26Amps with two people in the sim but most of the time it was only using 15-20 Amps so I am confidant that the Sabertooth with peek current spec of 60amps should be happy enough.

Let the fun begin .
Have any thoughts let me know.

Here is a picture of the M4 Motion theatre

Thanks Noorbeast,
I am not sure how you define it as a commercial activity or what that means exactly ?, sorry if i posted in the wrong spot im new here , it was a commercial sim as previously used as a ride but the plan is to re-engineer the thing for playing car games and flying xplane as the hardware was retired some years ago and parts of it are missing, but it seemed like an interesting project and I am only doing it because it sounded like fun and thought I would share the experience as I start messing about with simtools and motion platforms , I dont build motions sims for a living or have any intention on selling them but yes he is a client and Friend from other unrelated business activities and he asked me to take a look at it and see if I could get it up an going and as I am not working currently due to personal health reasons and it sounded like fun, some people like to go fishing i like to tinker with electronics and computers.
I have build a few high end computers for flight sims and gaming machines in the past but not motion ones so this is really something different and interesting, again im not sure what defines a motion platform project as commercial , but i would not have personally thought it to be a commercial project, still if you think it should be in a different area I will leave that to you.
cheers.

So over the weekend and today started testing the setup with the kangaroo x2 and Sabertooth 2x32 , I mounted everything in a project box to make it a little more robust then just floating around on a bench, added a DC to DC converter for a 12V source for the fan and anything else that needs a supply , such as the relays i will perhaps add later for an emergency stop switch.

I had a usb to serial cable to talk to the Kangaroo but that did not seem to work for reasons that eluded me so bought a FTDI Usb to serial TTL board for adrino at Jaycar for about $20 and that seems to work fine , so loading up the describe software and tring to figure out how to successfully tune the kangaroo x2 , which at this point we are yet to achieve, problem seems to be that because the first motor axis actually does not have any limits it can turn 360 degrees which for the self learning on the Kangaroo seems to be a problem it just keeps turning till it times out, and i am yet to figure out how to be able to use the kangaroo with out a successful tune or perhaps i need to trick it somehow to think its tuned by adding limit switches but hopefully not , i tried sending serial commands but it just gave an E4 error which means its in the wrong mode, unfortunately going through all the documentation on the kangaroo , sabertooth and Describe software, i came up with nothing seems theres nothing documented on skipping the automatic tune , so I am stuck as to what to do at the moment .

From the Describe software in the tuning setup you can manually control the motors that all seems to almost work now, however, what was interesting was that the encoder for motor 1 seems to work fine , but the encoder for motor 2 seems to some how be sending encoding to the actual motor 1 as well so i move motor 1 and motor 1 lines value changes and then i move motor 2 and motor 1 line value changes also , and after checking the wiring several times I am a bit stumped as to why its doing this ?
While there is a lot of cable to the encoders I will need to put an ossiliscope on the encoder channel pins and just make sure that there isnt some signal cross over happening somehow or perhaps pull up resistors may be needed, further investigation will hopefully resolve what is going on, or perhaps theres something software related messing it up , I just dont know.

So anyone out there with some kangaroo experience got any ideas ?

Hi If I understand your problem it seems to be the same issue I had early in my use of the Kangaroo . basically if one of the pots is not connected then the other signal is floating and cause the problem your seeing , if you connect a dummy ppt temporally the problem will go away .. basically you need to set any unused pot signal to ground or +ve I think , that's what cured that issue for me .. nice work

Hi. I wrote the interface for Simtools and the kangaroo. However, for transparency, I don’t use the kangaroo myself and only did bench testing to make sure the interface worked.

First, on serial converters, FTDI and the cp2102 from Silicon Labs both work great with the kangaroo or sabertooth. The cp2102 can be got for much less money though. However, the ones I got had the tx and rx markings reversed so you could try that on the converter that didn’t work for you if you haven’t already.

To autotune without limit switches or when not using pots you will need to do a teach tune. See the kangaroo’s manual.

I don’t know about your other issues though because I didn’t do any testing with encoders.

Honestly though, even though you probably don’t want to hear this, I would consider tossing the kangaroo and going a different route. The kangaroo thus far has turned out to be a real disappointment when it comes to simulator implementation. That said though, you may have a better chance than others getting a good autotune since you are using encoders without limit switches. Your rig will work more or less the same as a battle bot does and the kangaroo was designed more for that kind of thing.

Another option would be to go with the SMC3 motor controller for Sabertooths instead or Vinsils sabertooth controller. Two things to keep in mind though are that you would need to find a way to use them with encoders instead of pots. And, even when using the kangarroo, you will also need to change the “units” command in my simtools interface to numbers that match your encoder type. The units command posted is for pots only with 12bit simtools output.

Good luck!

ps Also, in Describe software in the Control tab, clicking on the advanced button will access the autotune settings.

When using encoders this should not be an issue since the ADC, which causes the problem with pots, is not being used.

Hi @BlazinH my bad for duff info Thought he was taking about pots , if only we could get to encoder without going through The Kangaroo Nirvana other than blowing or should that be shorting a couple of my Kangaroos ( which have been replaced) I sortta hit the buffers trying to do the Autotune with encoders inputs to the kangaroos ( you may need to fit Pull Up resistors I did on mine ) I was getting great control but for some reason it would not Home under power ( Motor seemed very weak and had to manually trip the limit switch on some axis's ... Most probably my fault as I do like DE stuff , Some more explanation for the layman in their Describe Manual would be great but that's just Me , Cant really fault the product just because I don't know how to drive some aspects of it ,, wont give up on this, but making good progress with my Linear actuator 6 DOF project so may well revisit the Encoder and kangaroo option one day in the future .. cheers once again for top notch info all appreciated

thanks for all the suggestions and responses , i think i will test the encoder signals for motor 2 with a oscilloscope as that seems to be messed up, see if i can get a teach tune completed , and i will try some pull up resistors on the encoder signals.. see how we go .. cheers

Had another play with the simulator project today , but only had a limited time so did not make a lot of progress, using an oscilloscope i checked the encoders input to the kangaroo and seems theres a wiring issue going to the second encoder, I traced it back through the cables and it seems that i have a missing ground wire that isnt connected where its suppose to be as i just went of the wiring that was on the first encoder plug and assumed that it would be identical on the second encoder, such is not the case it seems , I ran out of time to fix it today but when i go back I will rewire the encoder cables so that they at least match the pin configuration on the other encoder cable and hopefully will be then able to get the second motor encoder data and complete a tune.
may need to replace some plugs one is damaged so it may be that the break is in that one, but this machine was built in the US some 15years ago and finding the same plugs has been another difficulty , i will post a picture of the encoder plug perhaps someone may know where I might find a replacement.

well what a day so exciting now that progress has been made !
A successful tune which means now it gets fun
Anyway the problem was anytime i would start the manual tune in the Describe software and move motor 2 , i would get lines counting on encoder one when nothing was moving , so frustrating !

So with soldering iron in hand I added pull up 1k resistors to encoder inputs A , B and Z ( index ) , but no result , then tried pull down resistors as i think pull up is for an inverted signal , pull downs seem to clean up the RF a little while pull up seemed to make it worse. after scratching my head pulling apart both motors, moving cables , then finally decided there was to many unknowns in the existing cables so I will just put in new shielded cables to the encoders and bypass all the junction boxes and plugs I had spent hours testing see what happens.

Seems Quadrature encoder inputs are very sensitive to RF noise , and after putting in new shielded cables it looks like the problem is now gone ( solved YAY ! )

Now both encoders are getting clean data , theres a chance the teach tune may actually work , and it did
And not to forget a big thanks to Dimension Engineering and their Help Desk for the fast responses and great suggestions that helped immensely with working out what was going on with the encoder problem, got to love it when you buy a product and can actually get some support, well done I recon.

So now on with the next stage ... umm setting up Simtools and installing a game plugin for which I will refer back to the great Guide to using simtools with the kangaroo by BlazinH .

I have to figure out the commands to put into simtools for my setup , that should be fun.
( hints are welcome )

I bought Dirt3 a couple of weeks ago and have been having quite a bit of fun playing that, amazing graphics and its really hard with the assists turned off so i play it with them on until i am better at it , I think I will give that a go first.

Theres still all the new hardware to install in the actual sim and a few tricks to get everything working through an 8 wire slip ring so I'll keep you all posted on how thats going , and latter drop some links to videos of it in action .

thanks for reading

thanks
And I am looking forward to sitting in it should be fun , im not so sure about the 360 degree rolls

In the describe software the range is -8000 to 8000 on CH1 and -1600 to 1600 on CH2 , is this counting equal to the number that I put in the start line , as my motors are in big chunky gearboxes I have no idea how many times they turn and while i know i have a MOD5600 encoder the resolution sticker isnt on the encoder so it could be 100,200,250,360,400,500 or 512

I tried
1,start<13><10>1,units4095=8000<13><10>2,start<13><10>2,units4095=1600<13><10>

but I go into Output testing when it starts it turns upside down then stops seems to only have one half of the movement perhaps i double the numbers ?

I am thinking that my previous startup output command isnt quite right, but from what im seeing it looks like simtools makes the assumption that the sim is on an actuator starts at 0 home position, on the ground perhaps if its an actuator then moves to half range when it starts , how do i configure simtools to stop presuming that it needs to travel to a mid point at startup as when ever I run a output testing thats what it seems to do , i cant see an option for it , and after every output test i have to close it , reopen describe software and re calibrate the home position which it started in , also does the shutdown output command actually run when you stop output testing or only in games ? because a return to p0 maybe a useful addition in there before powerdown there is also a powerdownall option mentioned in the kangaroo packet serial reference but the document is really lacking in syntax examples and im finding it hard to understand, certainly didnt seem to explain the "units" command in any detail.

I was playing in the serial console with commands and discovered that the start command actually resets the home position to 0 from what ever position its in at the time not ideal in my situation as i need centre to remain centre, as i was testing in a serial console what commands actually did and thought perhaps i could just run an additional command in the startup to like 1,p-2000 but that didnt seem to work either , the <13> <10> is that code for carriage return and new line ? are these codes explained some place that im yet to find ..

thanks

The units command simply sets up a ratio of the input to the output of the kangaroo. But if the kangaroo expects zero to be neutral when using encoders then the output of Simtools must be modified because it doesn’t normally output negative numbers.

When using 12bit output resolution from simtools, neutral position will be 2048. So if the kangaroo expects zero to be neutral, then you will need to do this in simtools output (I think simtools allows it) 1,p(<Axis1>-2048)<13><10>. Then the units command would be 1,units2048=8000 for ch1 and use 1600 for ch2.

ps. I'm not sure about the parenthesis though. If that doesn't work maybe brackets instead [ ] or none at all.

thanks for that i'll give that a go , that kinda makes sense too.

I dont know if this is relevant but theres an encoder calculator for units (mm) = (lines) on the Dimension engineering website
here _>
http://www.dimensionengineering.com...0&linetype=&ratio1=80&ratio2=1&calc=Calculate

now i scratched about for the numbers to enter a wheel size measured in who knows i guess millimetres , now wheel size is not mentioned on the BEI MOD5600 series data sheet, so i pulled off the cover and measured it at around 25mm , the boston gearbox has ratio 80 printed on it for Ch1 so im guessing thats 80:1 then I found the encoder resolution in the partnumber which is 100 , the codes it then suggests look very similar but maybe its something different

Here is what it gave me :

Exact
78.5398 mm = 8000 lines

Rounded
785 mm = 80000 lines (0.05% error)

Simplified Serial
1, UNITS 785 mm = 80000 lines

Arduino Code
Channel.units(785, 80000);

really does not sound right when 8000 lines was a full rotation in one direction.

cheers going to try your suggestion

Glad to know I make a little sense at least. Lol.

Since simtools doesn't output in mm that is useless unless you convert it to a bit range.

the first bit seems a lot better m1 did a full rotation m2 went down on the front , could not get anything with brackets or without
but its given me a better understanding of the commands and its a little closer