Drive train issues with clawbot and ike

My Vex IQ Clawbot won’t drive in a straight line. It turns slightly to the right when both drive motors are fully engaged. I tried taking it apart and readjusting wheels, knobs, and gears to eliminate any friction that would slow one side down. Any ideas?

Also, my Ike robot doesn’t turn properly. When I engage one drive motor forward and one in reverse, Ike starts “jumping” (the tires are catching too much centrifugal force as it attempts to turn). It almost seems like Ike’s “track width” is too long. I can’t imagine that Vex would give you directions to build a robot that doesn’t turn correctly, so I figure I must be doing something wrong. Anyone have any experience with this when building an Ike?

Thanks,
James Kinzer
Hawthorne Middle/High School

For Clawbot, make sure you calibrate your joystick.

Not sure what to suggest on Ike. Does he turn? You just think he turns poorly?

Steve

Seems like the sample bots are not supposed to be perfect. On the contrary, Ike is cute, but a good lesson in what not to do if you want a smooth driving robot that won’t tip over. Think of it as a teaching opportunity. What changes could you make to improve Ike?

Hi hawthorne,

We’re sorry that you have encountered this issue. To further help isolate what the problem may be, we have a few recommendations for things to look for. Since you have already checked for mechanical friction, we will check the Control System.

The first thing to look for is to make sure your Controller is fully calibrated. All Controllers are factory calibrated, but it is possible that Controllers may rarely need to be re-calibrated. The Calibration procedure makes sure that the maximum distance traveled by the joysticks on the Controller is read as 100%. With incorrect Calibration, the maximum signal from the Controller may only be 90% or 80% or etc. - this would always cause the robot to drift (because one motor would be commanded to go 100% and the other only 90%). We have a helpful YouTube video here showing the Calibration procedure:

The other item to look for (if the prior recommendation does not solve the issue), is to swap the two drivetrain Smart Motors around to see if the drifting follows a specific Smart Motor. If one Smart Motor is always slower, please contact our technical support folks at support@vex.com or by calling +1-903-453-0802 so we can provide additional assistance.

Regards,

  • Art