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Moneer81
(@moneer81)
Active Member
Joined: 7 months ago
Posts: 11
2020-02-16 3:53 am  

Hello,

I just picked upthis robot chassis from Servo City and my next step is deciding on a motor controller. I am a little overwhelmed with the options, and confused why the Cytron controllers Bill used are about $14, while others like the Sabertooth are over $130?

my requirements are:

- 4 motors, with a stall current of 4.9A each

- leaning towards using PWM from Arduino, but open to other suggestions (I also have a raspberry pi)

- most importantly: looking for a common popular setup. Meaning, when I run into issues, I’m hoping to be able to find other examples and suggested fixes. Not looking for an obscure board. Looking for a mature product with a community around it.

 

Any suggestions?


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triform
(@triform)
Estimable Member
Joined: 9 months ago
Posts: 215
2020-02-19 1:57 pm  

Hi @moneer81!

I have a Warden that I drive with a VNH2SP30 clone board.  They work but may take a few to get one that completely works. They come in one and two-channel versions on eBay etc and are really cheap, but...

IMG 20200219 082053

 

See it in action here:

I would recommend the Cytron 10a dual-channel driver to run it. Good power delivery, low voltage drop, easy to use and cheap.

Now, the reason high-end drivers cost more and some differences from low end drivers.

Motor controllers like the Roboclaw, Sabertooth and others use more expensive components and more of them sometimes. Some have an onboard uC to help things along. They also offer advanced functions like built-in thermal shutdown (though some inexpensive ones can as well), serial control options, RC control, power management, and channel mixing and more. 

Drivers like the Cytron are just that, drivers.  They are GPIO only controlled most of the time and have no extras.  They do the job, are easy to use and have nice fat MOSFETs to drive high current loads though.

Now, the Warden.  See my review video above.  It's a nice chassis and a good mid-size base to build on with a fair amount of room to grow.  I will warn you now "DO NOT STALL THOSE MOTORS"!  I am the reason they put the warning on the page now 🙂  They did not believe you could break one and I did (two).  I was doing extream turns and the gearbox did not like the stress.  This is something you normally do not do on a regular bot, but it was a review. 

Scott

 


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Moneer81
(@moneer81)
Active Member
Joined: 7 months ago
Posts: 11
2020-02-19 3:17 pm  

ha! that is your video!? I watched it many times on YouTube over the last few weeks as I was researching this chassis. Thank you so much for the thorough response. Based on what you are saying, I might go with the Cytron. I would not mind spending a little more to avoid the hassle and frustration to be honest. I actually called ServoCity and they recommended the RoboClaw 2x7A (around $69 I believe), so it is currently between these two (Cytron and RoboClaw). This is my first foray into motor controllers so I might be willing to spend a little extra for better support and documentation and libraries.

Thank you for your feedback on the Warden! I will not stall the motors, or at least I won't intentionally do that. I see that you put it to the test outside. I am planning on using it mainly indoors. 

One quick question about the Warden: were you able to add more weight and components to it? Any idea what the maximum payload it can handle? I am hoping to add components and maybe one day an arm but I am not sure if it can handle all that extra weight. 

I should be getting the kit any day in the mail now. Super excited!

 

This post was modified 1 month ago by Moneer81

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triform
(@triform)
Estimable Member
Joined: 9 months ago
Posts: 215
2020-02-19 3:34 pm  

Thanks.

You should be able to add 2-4 kilos on it.  I did run the motors on an 11.1v lipo, but only at 85% output of that. 

I would watch the chassis around walls, as I had it climb one in the house playing around 🙂

Scott

 


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Moneer81
(@moneer81)
Active Member
Joined: 7 months ago
Posts: 11
2020-02-20 5:02 pm  

ok great! should give me some room for additional components.

I will not make it climb walls! Although I am interested in finding a wheeled one day chassis that has enough power and is low enough to be able to go up and down stairs. I am wondering if the Agent 390 can do it. That looks like a cool chassis (a little more expensive though).


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