In the last week my teams have finished two new robots, running four and six motors. On both robots when driving with the controllers (Tank Control) the drive wheels would move slowly, in a jerking motion. On one machine the claw would open a bit when moving forward and close a bit when moving backward: as if there was some sort of “bleed over” from one port to the next. All of the drive motors were plugged into port 1 and 6. We changed the controller code, changed the batteries, checked for friction in the drive train, changed wheels and when we were out of options a student swapped out a brain from a spare Drive A Bot to their big robot and it now works like a champ. The same thing happened to the second robot and when we swapped out the Brain with one from a spare Drive A Bot it took right off at full power. Today I put one of the “bad” brains back in a Drive A Bot and it ran just fine with a controller. Has anyone had Brain issues like this? Should we travel with spare Brains to tournaments?
Are we talking VexIQ or Vex EDR here?
VexIQ has “smart motors” with the brain delivering constant power directly from the battery and the motor built-in electronics applying the power as commanded by the brain over I2C bus. There could be no bleed between the ports.
But the VexIQ built-in “Drive Controls” program expects drivebase motors on 7 and 12 in addition to 1 and 6, so if you had a claw motor in port 7 or 12, you could expect crazy stuff to happen…
VEX IQ. We are using custom driver control programs, we changed the ports in sensors and settings to match our robot. The only thing that changed from jerky movement to working well was changing the brain.
We’re sorry that you have encountered this issue. When you reference “custom driver control program”, are you using the built-in Driver Control program on the Robot Brain, or are you using a program such as ROBOTC or Modkit for VEX to write your own version of driver control?
If you are using software such as ROBOTC or Modkit for VEX, it can be helpful to see your program to help debug this issue further. If you do not feel comfortable sharing your program in public here on the forum (such as if this is a custom program for your VEX IQ Challenge team’s skills matches), the technical support folks at ROBOTC (if you are using ROBOTC) or Modkit (if you are using Modkit for VEX) can help provide additional assistance. You can contact them here:
Modkit for VEX Support:
VEX IQ. RobotC 4.5 We have a basic tank control program that also moves a few arm and claw motors nothing fancy 7-8 lines of code We just opened up the sample tank control program and added in our machine settings. We changed nothing in the code, controller or the robot except swapping out one bad brain for a different brain. We went from a robot that would not drive across the field to one that works just fine in the four minutes it takes to unplug and replug in a new brain.
I was just wondering if other teams have seen this problem. We had a practice match last Saturday and each robots ran in at least eleven matches with practice time and this has not happened again.
I am working on a sumobot challenge. We currently are having problems. My teacher said there is a way to modify the power setting from the default 85 power setting to 100. Is this possible? Please reply back.
am working on a sumobot challenge. We currently are having problems. My teacher said there is a way to modify the power setting from the default 85 power setting to 100. Is this possible? Please reply back. The end of the class is coming up soon. I dont have much time to get the power setting up. There is nothing in the guide.