Now that we have an understanding of the basics of simple movement, i.e.) motors can turn either forward (clockwise) or in reverse (counterclockwise). Let's explore what happens when we add a second motor to our Mimic and try to move a 4-wheeled robot forward.
Chances are that when you added the second command to control the left motor that the robot behaved unexpectedly. Why did the robot spin in circles?
Because the two motors are mirrored, when they go to turn forward (clockwise) one motor is going to be turning in the opposite direction.
Examine the pictures of a real-life 4 wheeled V5 robot below.
Sample V5 Robot with mirrored front motors.
The Left Motor looks normal. I.E.) It is right side up!
However the motor on the right-hand side is upside down, we know this because the VEX name on the motor faceplate is upside down.
This means that when both motors are commanded to spin forward, the left-hand motor will spin forward (clockwise), but the right-hand motor will actually spin in reverse (counterclockwise).
To fix this problem we will need to 'reverse polarity' for one of the motors. Meaning that the right motor will actually spin in reverse when instructed to move forward.
Now when both motors spin together the robot will propel forward instead of spinning in a circle.
https://robotmesh.box.com/s/85vkz7drmb2jme8f4d9jjbb7z8tsgwru