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bc414 13-02-2017 19:32

CIMs, Weight, and Max Speed
 
Will a 2 CIM per side drive train have a reduction in maximum speed when going from a 60 pound load to a 120 pound load? I am hoping to program autonomous using just the drive train and the electrical board while the rest of the robot is being built, but the algorithms I am using are dependent on the maximum speed of the robot.

DaveL 13-02-2017 19:39

Re: CIMs, Weight, and Max Speed
 
I would expect a slight decrease in speed due to increased friction on carpet from the extra weight. This is assuming traction wheels. I would guess that Mecanum wheels would have a larger decrease in top speed.

However i would expect the biggest difference to be in acceleration.

Dave

Lil' Lavery 13-02-2017 19:42

Re: CIMs, Weight, and Max Speed
 
Yes, you will have noticeably different performance between 60lbs and 120lbs.

Cothron Theiss 13-02-2017 19:58

Re: CIMs, Weight, and Max Speed
 
You can use the JVN Mechanical Design Calculator to calculate more accurate (not perfectly accurate, but very good) speeds for your robot.

bc414 13-02-2017 20:12

Re: CIMs, Weight, and Max Speed
 
If we strap on some metal blocks in order to increase the weight of the drive train to 120 lbs, will the drive train act similarly, or will the location of the center of mass change things? Is there anything else wrong with this approach?

elijah1111 13-02-2017 20:15

Re: CIMs, Weight, and Max Speed
 
Quote:

Originally Posted by bc414 (Post 1644449)
Will a 2 CIM per side drive train have a reduction in maximum speed when going from a 60 pound load to a 120 pound load? I am hoping to program autonomous using just the drive train and the electrical board while the rest of the robot is being built, but the algorithms I am using are dependent on the maximum speed of the robot.

If you are using encoders the speed would not matter. You could just read shaft revolutions.

ctt956 13-02-2017 20:28

Re: CIMs, Weight, and Max Speed
 
Quote:

Originally Posted by bc414 (Post 1644472)
If we strap on some metal blocks in order to increase the weight of the drive train to 120 lbs, will the drive train act similarly, or will the location of the center of mass change things? Is there anything else wrong with this approach?

There will be some differences with air resistance(though probably insignificant), weight distribution, and weight transfer when moving. Though I'm not sure how big of a difference any of these would be. If you do strap on metal blocks, make sure they're secured well so they don't go flying.

pmattin5459 13-02-2017 20:29

Re: CIMs, Weight, and Max Speed
 
Quote:

Originally Posted by elijah1111 (Post 1644474)
If you are using encoders the speed would not matter. You could just read shaft revolutions.

And I would recommend using encoders. Any system not measuring the motor's output is highly theoretical and can be influenced negatively by a variety of real-world factors, including friction in the gearboxes, differing traction on each side due to weight distrobution, etc.


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