Bad motor?

I just built another frame robot using my new competition add on kit. I noticed that when I was driving it using the controller that one of the motors was lagging making the 'bot curve to the left. It’s as if it would drive through 340 degrees or so of rotation and then would drag pulling the robot to one side. I think maybe that it has a dead spot in the windings because the other motor would keep turning and the wheels on the bad side would turn the bad motor via friction on the tires. I will double check this evening and see for sure that this is the case. What can I do to resolve this?


We are sorry that you are having this problem. There are two things to check to resolve this problem.

  1. Check the drive train of your robot to make sure there is not excessive friction on the side that is slower. If another part or Smart Cable is contacting any of the axles, gears or wheels it could cause friction which would slow down that side of the robot.

  2. You can check the performance of any motor in the Driver Control program. When the program is running, press either the Up or Down arrow to scroll through the information screens. On the Robot Brain screen, it will display the current speed of the motor in RPM while it is running. The maximum speed of the motor is 120rpm. If the motor is not reaching 120 rpm, press Up or Down arrow buttons again to get to the Controller screen. Does the Controller display +100% or -100% when it is at maximum reach? If the Controller is not reaching +100% or -100% you may need to calibrate your controller.


  • Art


I did recalibrate the controller before I started the Driver Control program and I got the values of 0,127,255 for both motors. I will go into the information screen this evening when I get home and let you know the results. As I used the shortest Smart Cables to attach the motors to the Brain and they aren’t even near any of the shafts or tires I am sure that is not the problem. However, I will use the replacement method to make sure that the cable isn’t the problem.


I have checked everything out. I have one motor that has a definite harsher sound than the other, like it is laboring more? Both motors are putting out + or - 100% and the cables did not make a difference in the outcome.