Quote:
Originally Posted by dellagd
It might be interesting to hook up a multi-meter to the wires that go to the wireless bridge and see if the voltage drops when you loose comms.
Also, just generally watch the lights on the robot and the bridge to see if anything changes from normal behavior.
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DMM might not see a drop out of brief time that will cause this problem.
An oscilloscope is preferred Voltage Vs time instrument but time consuming
Solicit an EE mentor to expedite scope usage.
A digital storage scope will view long time unsynced scan (DSO)
Seek out resources you have or can borrow.
Since problem is mystery, initially use long scan duration, if blob drop out is evident
try external sync to your suspected motor with faster scan to see detail over time of "glitch" or other suspected devices to determine root cause to fix.
Teams at each regional will have a scope for these hard time related problems: sagging bus, intermittent shorts, (RS-775?),
Potential Problem Note: high powered motors:
CIM RS775 & FP stall current each is over 100A
all motors start-up with a high brief stall current "glitch" ~50ms-350ms (low mass shooter - drivetrain)
depending on load mass, acceleration to speed varies as a function of gearing.
if geared too fast (like direct drive), glitch is longer, due to less torque available to move load to arrive at higher end speed
The longer & higher peak amplitude the spin up glitch, the lower the voltage dips to all other loads, especially sensitive electronically controlled ones for a longer time, potentially causing reset, drop out, reboot, jerky action, noise induced indeterminate's etc.
It is important to identify such basic problems early; gear changing can be challenge in the heat of competing.
For sure make good mechanically solid low resistance crimps, minimize insertion cycles of critical connectors and autoReset Breakers (20, 30, 40A) loose fit/crimp/screw = higher contact resistance! use welding cable stranded wire of heavier gauge especially on longer runs for less tension on connections and less path R.
competition batts drop ~1v at battery terminal for every ~50A drawn typically
then add Vsag from robot wiring resistance to load in question.
2 CIMS stalled draw 2x133A 266A causing >5v sag
at fully charged batt terms to 12.6-5= 7.5v
could be trouble once rest of wiring connection resistance is added say 5v or less at load for a few hundred milliseconds??
Excluding average state of charge battery Rinternal = .020 ohms
Is rest of your the total serial current path out & back to batt consisting of connectors, crimps, wiring, 2 breakers, total less than .010 ohms? if exactly then .01*266 = another 2.66v GONE! 7.5-2.7=
4.8v at load end voila!!
Good Luck .. hope this inside knowledge may help find the culprit...
I'll be at LA (=Long Beach) & STL as bearded iridescent green capped RI to help teams with tough electrical problems.