EV3 programming

Some of the reasons that robots don’t drive straight

Here are some of the reasons that a typical EV3 robot might not drive straight and some suggestions.

• Variations in the friction or other internal factors affecting performance of the motors. Try swapping over the motors or replacing them if you have spare

• Carpet pile direction. Try running the robot in the opposite direction, or at right angles

• Centre of balance / symmetry. Check for symmetry in terms of construction, weight, material, wheels, axis of rotation, and balance. Is there more friction on one side, and possibly slipping on the other?

• Robot construction. Check that the wheels are well connected to the axis and frame, and that the beams and other bricks are firmly connected to each other.

• Caster wheel not aligned, sticking. If there are free wheels in the back, make sure that both of them are placed in equal directions before starting the robot.

• When starting the robot, try to make an even pressure on the start button, otherwise the robot may not start straight. Try putting a short wait time after pressing the button, so that the pressure of your finger doesn’t cause problems.

• Motors have a small amount of internal gear slop (or backlash) between the encoders and the drive shaft that may affect initial trajectory.

• Wheels or gears catching or rubbing more on one side than the other.

• Different wheels might have slightly different circumferences.

• Dust/dirt causing a loss of traction. Clean the tires and perhaps sweep the floor.

• Try using brake, not coast, to finish a movement.