current drive of motor for robot

[garg29]

dear friends
m making a four wheel car in form of a robot. i have used two motor on the back side wheels. the motor is running on 12 v and has 200 rpm each. how can i calculate the current drawn from each motor so that i can make its control using power transistors. i actually want to make the car form robot turn on the either sides when needed.
can anybody please help me
with best regards
amit

 

[neoaspilet11]

Hello Garg,
Try to look at the motor specs MAXIMUM RATED Power. This is the maximum POwer the motor can consume during maximum load - e i maximum torque produce. Divide the voltage from the maximum rated power, you get the maximum current possible to pass through the motor.

Hope this help

 

[MirekCz]

take an amperometer, set it to the highest current measurement (like 10A minimum, no idea what engine you have there) , connect motor to your battery via amperometer and check current when motor is stalled (ie you are holding it tight so it can't rotate). This is your worst case current (it can be smaller then motor maximum current, if your battery isn't able to provide higher current... of course it means your safe as your transistors will never have to withstand higher current then your battery delivers)

Most hobby robots use motors with low current requirements (from 100mA to few A when stalled) - in those cases go for a ready to use circuit like L293C , L293D or L298.

Some motors (especially high quality model hobby motors for cars, boats and airplanes) use from several A up to over 100A of current... those are great motors, but not really for a robot unless you want to build a very heavy and/or fast robot.

 

[yangxh]

The current is much more sensitive.When you want to calculate the motor current to control its movement.You should know it.I agreeivide the voltage from the maximum rated power, you get the maximum current possible to pass through the motor.

 

[wini]

I think U do'nt need to calculate. The easy way to know the current drawn from each motor by run the motors from dc source ( 12v ) direct without connect any electronic item and then U can measure the current that enter to each motor.

 

[polus]

Just backing up what everyone has said: P=V.I

Where
P = power
V = Voltage
I = Current

(I apologise if Im teaching you to suck eggs)