I'm trying to make a self balancing robot and I'm having a little problem deciding which DC motor to buy.
My problem is that the majority of motor that I find have its stall current well above my motor driver mac current specification.
My driver can handle 2 amps for each motor. The load current of the motor are all lower that 2 amps. Do I have to get a driver that handles higher currents in order to use this motors?
I know that stall current only occurs when I lock the output shaft, since I'm going to use the motor with wheels, do I have to worry about the stall currents?
Noob question, I know. But, since this is my first project using DC motor, I am a noob.
I recommend that your electronics should be able to handle the "worst case". I believe the motor will draw the stall current (or nearly the stall current) when you start or reverse it.
Hi, The other approach sometimes used, but a little risky, is to "soft start" motors with PWM power control, and make sure that Magic Software never really starts or stops the motors instantly. Also your drivers MAY have Overcurrent Protection that would make them surviveable in a fault.
In your application you need the drivers to have a higher amp rating than your motors. Because you are using the motors to balance the robot they need to be able to respond quickly to minimize the amount of distance coverred to get under the center of mass when the robot is disturbed. With soft start the robot could cover a lot of ground because the motors can't accelerate fast enough to get under the robot. Kind of like trying to get your balance on rollerskates - you fall over a long distance while trying to get your legs underneath you... To balance teh motors are going to be going from forward to reverse and back again many times a minute, and they need to have ful torque in order to do that.
With soft start the robot could cover a lot of ground because the motors can't accelerate fast enough to get under the robot.
But, this is an interesting thing to model. I have ridden Segways a few times. (Once at 100F in the Sun in Saudi Arabia!). Rocking fore and aft, it seems to me that the motor power is ramped a little, not hard switched. If you lean forward pretty hard, it accelerates fast but smoothly. Think about standing vertical and then smoothly falling on your face. There is at least 1 second where the rate of change of angle of your back is less than 30 degrees per second or so. I think..
