Drive train stuttering


#1

Hello

We are using the andymark raptor drivetrain and we our experiencing our drivetrain stuttering while driving.

We are also running the compressor on the bot as well. When we unplug the compressor our drivetrain does not stutter anymore.

The game manual clearly states you need a on board compressor but can we disable it by either unplugging it or using code to turn it on or off during a match


#2

Is your battery voltage dropping significantly? If it is you might want to check all of your electrical connections and ensure you don’t have any loose wires. The connections of the battery cables are especially important.


#3

It sounds like you are drawing too much current or you have a loose connection somewhere. A place we have had problems before is with the wires that connect from the battery and breaker being loose. You could also just have a battery that is low on charge to begin with. They should usually be above 12 volts when you’re driving.


#4

Step 1: Buy a battery beak
Step 2: Check all electrical connections, especially to and from your PDP. Make sure your wires are only as long as they should be, do not leave loops of wire on your robot as this just adds resistance to the system.
Step 3: If your batteries are trash, buy new ones. I highly recommend purchasing directly from MK Batteries.


#5

We checked all of our connections and batteries and there all fine

We do not have the same issue with our practice bot

Could it be the compressor giving the voltage issue?


#6

Yes but if you’re only running your drivetrain and your compressor it shouldn’t stutter unless you’re doing like an 8 775pro drivetrain with no current limiting.


#7

All the other posters are correct, check all your connectors, etc.

However, to answer this, there is no requirement that you run the compressor during the match. We pre-charge a whole bunch of tanks when queuing and then change the battery for the competition. Our compressor does not run during the match, unless turned on by the driver (has not needed it yet).


#8

Sounds like your motors are running against one another. When they push against each other, it moves slowly and draws a ton of current, draining your battery. Try plugging the motors in one by one and driving forward to make sure all of your motors are running in the correct direction.


#9

if your motors are running against each other they usually don’t stutter. The stuttering makes me think there’s a loose connection somewhere and when they drive around it bounces around causing the stuttering.


#10

The stuttering is caused by brownout, which is being caused by the extreme amperage draw from the fighting motors. Unfortunately, I’ve seen it myself many times.


#11

If they’re running against each other it just shouldn’t move not stutter.


#12

Not if the drivetrain has an odd number of motors.


#13

Did you check the battery wire connections at the PDP? You must remove the two screws holding down the plastic shield to get to it. We spent hours at a competition chasing a similar problem and this is the one place we didn’t think to check.


#14

Fair enough. I had assumed 2 cim lol. Yeah that’s definitely a possibility then.


#15

I don’t think this is the cause because if the PDP was losing power the entire control system would be rebooting and stuttering, which it is not. I think it is an amperage draw issue on the motors specifically.


#16

Check the driver station logs. You can see your overall current draw, as well as the current draw for each individual WAGO connector on the PDP. That should help you isolate the issue a little easier.


#17

That’s what I initially thought when we had this problem. Our PDP wasn’t losing power, but the loose connection was causing significant resistance and thus a voltage drop in the circuit. This loose connection was very likely the culprit as the shield was melted directly above the lug. It’s likely that you’re correct, but this is an easy thing to check and it caused my team a problem similar to OP’s at an event this past weekend.


#18

What do you mean by “fine”?

If you can rotate any of the bolted connections with your fingers, it is not fine and should be tightened.

Do a pull test on each and every wire, individually.

Use a bright light and look around all your wires going into the Weidmuller connectors from different angles. If you see anything shiny, you have either wires with too much insulation stripped off and/or stray strands that are not in the connector.


#19

We had this exact issue when we first started testing our drivetrain. The problem was motors spinning against each other. We are using the WCP DS Gearbox, so 1 mini cim was spinning against the other 2 mini cims.


#20

Why would you need to limit the current again?