Robo Claw Motor Controller NEW

When choosing a component, I tend to seek a high safety factor. Stall amperage on DC motors can be very high--particularly when they reverse. So a motor that is moving a lot might tend to generate much more heat than the "design load" amperage. I am guessing that a 1/4 HP motor designed to draw 20 amps might regularly see 50 amps running a Sim at a fast road course with lots of direction changes and slower corners requiring heavy braking followed by full throttle.

The kangaroo sounds good and they say it will work for motion simulators but most members I know that have tried it have had problems getting a good auto tune and/or the proper type of motion we need. You are welcome to give it a try but I have not been recommending it until someone can prove it works well and how they did it. I mostly was in contact with Dimension Engineering over how to set up their simple serial mode on the kangaroo to use with simtools, not how to get a proper auto tune, etc. While the people there are nice and try to help, in the end, they couldn’t tell me what I needed to know (even the engineer) and I had to figure the code need out for myself by emulating a terminal program.

The sabertooth motor controllers themselves are the bomb though!

A couple videos showing the Kangaroo and it's teaching mode. Potentiometers would almost always be cheaper, but the Encoder seems "interesting" if you believe in the value of digital vs analog. The Kangaroo is very "friendly" to encoders with an I terminal for three channel "indexed" incremental quadrature encoders and L1,L2 terminals for limit switch option. Picking a 1024 pulse/rev encoder gives accuracy of 0.4 degrees for 180 degree of motor travel--that is probably about 1/8" of shoulder movement on a shaker seat. Most potentiometer linearity limits in that range.

See below answer from Robo Claw about POT control. A bit "greek" to me.


Post subject: Robo Claw using POT-Race Simulator
Posted: Thu Nov 13, 2014 5:10 pm

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Joined: Thu Nov 13, 2014 4:51 pm
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Trying to figure out how to use Robo Claw to operate DC Motors using Potentiometer Feedback. Typically the motor rotates 0-180 degrees with 90 degrees being "home".

Do we need an Arduino to control the Robo Claw in a way like we use the MotoMaster or can we use the PC Serial Output from the Simulator Software? See link. If so, could you post a sample of the lines of code required for the Arduino?

http://www.xsimulator.net/wp-content/up ... -setup.png

If we choose an encoder, how would you suggest we make it move back to "home"?



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Acidtech
Post subject: Re: Robo Claw using POT-Race Simulator
Posted: Sat Nov 29, 2014 1:32 pm

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Location: Temecula, CA
You should use the IonMotion software to setup the roboclaw to use the POT as an encoder. The pot signal should connect to the A channel of the encoder for the particular motor channel you are using. In the general settings in IonMotion set the encoder type to absolute.

Then to use position control you will need to setup the variables in the position settings tab. There are a lot of settings. At a minimum you must set the QPPS, Position P and D and Position Min and Max. Everything else can be 0.

To calculate QPPS with a POT can be tricky because its got limited range of motion. In the PWM settings window run the motor at 150(1/10 full power) and read the speed value. You are looking for the max speed reached. Move the motor back and forth at +-150 since you have limited range. Once you know approx speed at 1/10 multiply that value by 10 and that will be your approx QPPS.

back in the Position Settings windows.
Set min and max to the range of your pot(in encoder counts) with about 50 to 100 margin so you wont damage the pot if the motor over shoots.
Set the Speed argument to the same value as QPPS.

At this point you can try using the autotuner. Set the drop down to PD and hit the autotune button for the motor you are tuning. Be ready to shut everything off if something goes wrong. This usually only happens if QPPS is set badly wrong. Other wise the motor should move a bit and oscillate a little for a couple seconds and then stop. When its done you hsould have some values in P and D. If they say "infinite" then it failed to autotune.

In either case you will probably want to do some manual tunning even after the autotuner is finished.

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Well I see they finally answered! But after reading all that, and considering that Simtools can already use the kangaroo motion controller, and it can use a pot, it seems like it is the better of the two at this point at least. I thought they said it should be easy! Also, since you like to talk about latency, the kangaroo only needs one byte per motor used to control it from Simtools. The Roboclaw would require several bytes per motor used and a checksum to be calculated each time as well.

Edit: It actually takes more than one byte to control each motor with the kangaroo because Simtools is sending text commands to it. Each character sent will take one byte. I control my sabertooth motor controllers (without the kangaroo) though using singe byte commands.

People at Dimension in Ohio are very helpful and informative. The Robo Claw people were much less so.

I will be going with Kangaroo and encoder..will try without Arduino but if Arduino is needed or desired I have a programer available to assist with adapting their library.

I have great respect for Carnegie Mellon Robotic grads like those at Dimension.

You don't need an Arduino. The kangaroo is your Arduino. You just need a Sabertooth or SyRen motor controller to go with it along with a serial port or usb to serial converter on your computer.

Thank you. I'm hoping it is simple. I guess the Arduino library they have is if you don't use Kangaroo.

You need to use an arduino with the kangaroo if you want to use packet serial commands instead of simple. http://www.dimensionengineering.com/software/KangarooArduinoLibrary/html/ . But their is really no need to use packet serial unless you want to retrieve information back from your kangaroo or you are having transmission problems since packet serial uses a checksum where simple does not.

ps We only need an arduino to use packet serial with Simtools right now. In the future a kangaroo plugin could be developed using packet serial commands if needed.

any news here? I do not know yet if one of my MM's has blown (one motor stopped, SMC3 shows power on), tomorrow I will check out my hardware. If one MM failed, I would be interested in going on with the 2x60A RoboClaw. 2x60A continuous and 120A peak - that is not to be sneezed at.

PS: no MM has ben blown, a cooked wire has been detected.......

I am very keen to see these working with Simtools.

My motors draw over 70A peak and they are causing the JRK's to error. I have limited the duty cycles which help but they still overload on extreme corners.

The 2X60A (120A peak) would be perfect for my simulator.

It looks great!
Although I basically didn't understand most..

Please someone of our native English speaking guru members can go at http://forums.orionrobotics.com/ and ask for a dedicated support...?

The roboclaw in simple serial mode should be compatible with the sabretooth... therefore the SMC3 sabretooth TEST controller should be able to drive them...

http://www.xsimulator.net/community/threads/smc3-sabretooth-test-version.6236/

G'day guys

Has anyone ever gone though and built one of these. I current use sabertooth 2 x 60 for my front 2 motors they handle my sway and surge and I run a syren 50 for the single traction loss motor. and got an email say the syren 50 and sabertooth 2x60 chipset is not available for 20 weeks due to world events.
I'm looking for a solution
I'm keen on a robot claw or sabertooth 2 x 32. Did anyone complete a test sample or get then robo claw working on simtools?

Hi guys i got he boards now how anyone used these before?

Thanks mate ill just have to wing it and try it out