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Unread 04-16-2018, 12:18 PM
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Suggestions for Motor Controller

Hello,
We are looking for a suitable motor controller, but so far we are unable to find one which meets the following requirement:
We have a 4 wheeled robot with a payload of 150kg, and according torque and speed requirements our current requirement is 120A per wheel.
Currently we considered using 12 Talon SRX (one with each of the three motors per wheel). Is there some better solution available? Something that is within the cost range of approximately1500AUD.
Thanks a lot.
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Unread 04-16-2018, 12:27 PM
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Re: Suggestions for Motor Controller

Sparks can handle up to 60A a piece and 120/3=40. If you're looking for a cheaper option those are only 51.50 AUD each.

Half the price of talons, biggest difference is that it runs PWM instead of CAN. Which could be nice because you can use PWM splitters to run the 3 motor controllers per wheel as one, streamlining programming.
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Last edited by darajaco : 04-16-2018 at 12:31 PM. Reason: Adding more PWM info
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Unread 04-16-2018, 12:32 PM
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Re: Suggestions for Motor Controller

Is the requirement 120A per motor or per wheel? If it's per wheel, then each motor controller only needs a continuous current of 40A, which is well within any FRC standard motor controller. If it's per motor, no FRC motor controller is rated for this.

Either way, using Talon SRXes is very expensive, twice as much so as the cheapest option. The only reason to use Talon SRXes is if you're using the built in closed loop features (onboard PID loops, current limiting, voltage ramping, etc.) If you're not planning on using these, then there are much cheaper options available, like the Spark controller or the Victor SPX, both of which support PWM. The Victor SPX also supports CAN, but if this is for a non-FRC project it may be more trouble than it's worth to port the libraries.

12 Sparks will set you back only $480, opposed to the 12 Talons which will cost $1080.
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Unread 04-16-2018, 12:33 PM
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Re: Suggestions for Motor Controller


120A per wheel you say. How many (and what type) of motor(s) per wheel?


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Unread 04-16-2018, 12:34 PM
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Re: Suggestions for Motor Controller

I'm curious how you determined what your current requirement per wheel is.

Also, I'm curious how long this much current will be needed, or if the current demand drops off quickly once the robot begins moving.

Knowing these things, might help others help you determine what you really need.
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Unread 04-16-2018, 12:38 PM
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Re: Suggestions for Motor Controller

http://www.ampflow.com/vex_motor_speed_controller.htm

I saw these when I was looking into battlebots. Looks like a Victor on steroids. I'm not sure if they make them anymore, though.
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Unread 04-16-2018, 12:46 PM
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Re: Suggestions for Motor Controller

Quote:
Originally Posted by Chadfrom308 View Post
http://www.ampflow.com/vex_motor_speed_controller.htm

I saw these when I was looking into battlebots. Looks like a Victor on steroids. I'm not sure if they make them anymore, though.
Chad those are 400 bucks a piece
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Unread 04-16-2018, 04:00 PM
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Re: Suggestions for Motor Controller

Quote:
Originally Posted by darajaco View Post
Chad those are 400 bucks a piece
But they are also rated at 300A continuous.... so it is possible they could use 2 of these controllers.
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Unread 04-16-2018, 04:09 PM
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Re: Suggestions for Motor Controller

Quote:
Originally Posted by RoboChair View Post
But they are also rated at 300A continuous.... so it is possible they could use 2 of these controllers.
Depending on drivetrain style might not be practical, if regular tank drive then yes makes sense but for mechanum or swerve (more likely set ups for 4 wheel independent driving) youd need the extra controlers.
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Unread 04-16-2018, 04:23 PM
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Re: Suggestions for Motor Controller

Quote:
Originally Posted by RoboChair View Post
But they are also rated at 300A continuous.... so it is possible they could use 2 of these controllers.
"estimated 300A continuous" - why "estimated"?
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