Hi,
I wonder how to control the motors in those 4WD cars so that they do not react to each other. Normally one motor would run faster than the others even if they are the same type and model, and this would impose forces to the other wheels and motors.
What sensors do they use to detect the non-synchronisation of rotation speeds and how to solve this using control theory?
I assume that you are talking about remote controlled cars?
You need a rotation sensor, preferably on the wheels. Commonly, that would be a disk with black and white fields around its outer edge. The change of black and white is picked up by a light sensitive device and compared to the number of expected stripes passing by the sensor. Then motor power is reduced or increased, depending on the error.
Thre are ready made encoders in various resolutions available.
"eeh" schrieb im Newsbeitrag news: snipped-for-privacy@o13g2000cwo.googlegroups.com...
Torgue - when cornering, the speeds will be different. The simplest is to measure the motor currents, which will be proportional to the torgue. The speed will be proportional to the "free-wheeling" motor voltage.
Not Exact Measurements - but good enough for practical work.
What 4WD cars would that be? If you are referring to RC cars, they don't worry about it at all.
2 motors, 2 axles, 2 open differentials, 1 guy using visual feedback to make adjustments to the steering as required. Some of them even gang the 2 motors onto a common gear and use a rudementary transfer case.Jim
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