In a 4WD configuration, is it necessary for the motors on the same “side” to be completely in synchronized; or is it okay if there is some variance in their speed?
**It is important that the wheels be geared for the same speed, however minor variances due to factory motor difference are negligible.
With slight motor variance, the wheels work against each other a little bit, but will still run fine with negligible power loss.
If this becomes a major concern, there are ways of mechanically syncronizing the wheels together (as seenin the construction of the square-bot, shown in the Inventors Guide).**
What is the benefit of this arrangement, since the speed is “the same” on both motors on each side. I suppose I can expect a torque increase but not a speed increase. I this correct?
**Yes, this is correct.
Using 4 motors, provides double the power of 2 motors.
(Refer to the Physics of “mechanical power”.)
The motor loading, is spread over double the number of motors, therefore the load on each motor is halved.
This means that at a given gearing, there is twice the stall-torque available.
This also means that the robot will accelerate twice as fast at a given speed, or be able to be geared twice as fast and keep the same acceleration.**