|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
|
|
Thread Tools | Rate Thread | Display Modes |
|
|
|
#1
|
|||
|
|||
|
HELP: Voltage Drop
When testing our robot, we were getting a voltage drop to 6V when going over the obstacles. When going over the carpet we have been dropping voltage to 9V.
Our robot has 6 8" pneumatic wheels powered by 2 cims in a toughbox mini each controlled by a talon srx It has 2 window motors for lifting our arms each controlled by victors 2 mini cims for shooting each controlled by talon srx. (we are planning to swap these out for banebots RS-775 or 775pros ) We also have noticed the front CIMs on our drivetrain getting really hot. Our drivetrain does not have the center wheel dropped. Currently we do not have the time to create a center wheel drop. |
|
#2
|
||||
|
||||
|
Re: HELP: Voltage Drop
What's your battery voltage when you're not moving (idle)?
|
|
#3
|
||||
|
||||
|
Re: HELP: Voltage Drop
With all these topics on power draw I am really surprised to not see any current readings from the PDB. With voltage and current it would be more clear what is drawing all that power.
|
|
#4
|
|||
|
|||
|
Re: HELP: Voltage Drop
We just checked and its from the drivetrain cims. But the front cims are drawing the most power while the back cims aren't anywhere near that
|
|
#5
|
||||
|
||||
|
Re: HELP: Voltage Drop
Quote:
Are the wires to the 'rear CIMs' much longer than the 'front CIMs'? |
|
#6
|
|||
|
|||
|
Re: HELP: Voltage Drop
Are both SIMs in each Toughbox pair being driven in the same direction? If they are fighting each other, I wouldn't be surprised to see this. We always run one at a time as a first test to make sure they are going the right way.
Ken |
|
#7
|
|||
|
|||
|
Re: HELP: Voltage Drop
We have tried that and found that they aren't fighting each other.
|
|
#8
|
||||||
|
||||||
|
Re: HELP: Voltage Drop
You are not clear if you have 4 CIMs or 2 CIMs. I assume 2 CIMs PER SIDE is your configuration.
Are all 3 wheels & all CIM on each side drive train mechanically coupled (chain, belt, gears) such that rotating one wheel rotates all wheels and all motors? Or do you have a different configuration (e.g. front wheel driven by 1 CIM, back & center driven by another CIM)? All ratios from motors to wheels (and size of wheels -- but we already know that 8") are also needed to answer questions intelligently. Dr. Joe J. |
|
#9
|
|||
|
|||
|
Re: HELP: Voltage Drop
Quote:
|
|
#10
|
||||||
|
||||||
|
Re: HELP: Voltage Drop
Quote:
As to the 9V when you are just on carpet, this is not turning right? If it is turning and you have not lowered the center wheels as you have said, then this is just normal behavior, but if it is going straight, then it could be that your pool noodles are not consistent and as a result they give you different circumferences for each wheel. Again, with such a high CoF, your motors are busy turning electrons into heat just due to these variations in wheel circumferences. What to do? Well, put your robot up on blocks and see what the current draw is. It might be that you have losses generally that are causing you to start in a current hole to begin with. Look for tight belts, sticky bearings, mis-aligned axles, something rubbing against the wrong bit of a bearing (you want your wheel's thrust load to go into the inner race of the bearing not the outer race or the shield). Assuming you can get the off the ground current to something manageable, then it is time to get real about wheels. 6 wheel drive with these tires and no rock from lowering the center wheel is a slow motion train wreck. You have to fix that. Go back to air on the center tire and over inflate that tire, put some tape over the front or rear (or both) wheels) to make them less grippy, switch to another wheel style for the front or back (or both) wheel, figure out SOMEWAY to give yourself some rock in your chassis. Good luck... Dr. Joe J. |
|
#11
|
|||
|
|||
|
Re: HELP: Voltage Drop
Quote:
|
|
#12
|
|||
|
|||
|
Re: HELP: Voltage Drop
Yes. That's the issue. And the wires to the rear cim is about the same length as the front cims
|
|
#13
|
||||
|
||||
|
Re: HELP: Voltage Drop
Quote:
Quote:
Did you guys do any calculations before selecting wheel diameter and gear ratio? |
|
#14
|
||||
|
||||
|
Re: HELP: Voltage Drop
I would say the most likely issue is using 6 pneumatic wheels without a drop center. That's a whole lot of scrub when you try to turn, and that will eat your battery like you wouldn't believe.
|
|
#15
|
||||
|
||||
|
Re: HELP: Voltage Drop
Is there a troubleshooting flow chart for this?
I mean I can easily find 6 topics on related issues. Maybe it's time someone makes a troubleshooting flow. |
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|