M
Marco Trapanese
Hello,
I'm sorry for my English. I have a question about stepper motors.
I used a unipolar stepper motor (200 steps/rev) to control an
electro-mechanical brake. It must move as follow:
1) 50-60 steps clockwise as fast as possible
2) hold position for about 20 ms
3) return (CCW) at initial point as fast as possible
4) hold position for about 200 ms and then go to 1)
Note: the load is very light.
Using a PIC, a ULN2803 and a 12V zener on the Vdd it completes 1) or 3) in
less of 100 ms.
Now, I have to improve (if possible) the performances. So I ask you:
1) What type of motors are more suitable for this application? unipolar or
bipolar?
2) Should I use a chip (ex. L297/298) to driver the motor? Most of them have
a PWM driver, I think it could be more efficient than a simple Darlington
driver.
3) I used a "pseudo-exponential" ramp to accelerate/decelerate the motor.
What curve do I have to follow to reach the best acceleration/deceleration?
Thanks
Marco / iw2nzm
I'm sorry for my English. I have a question about stepper motors.
I used a unipolar stepper motor (200 steps/rev) to control an
electro-mechanical brake. It must move as follow:
1) 50-60 steps clockwise as fast as possible
2) hold position for about 20 ms
3) return (CCW) at initial point as fast as possible
4) hold position for about 200 ms and then go to 1)
Note: the load is very light.
Using a PIC, a ULN2803 and a 12V zener on the Vdd it completes 1) or 3) in
less of 100 ms.
Now, I have to improve (if possible) the performances. So I ask you:
1) What type of motors are more suitable for this application? unipolar or
bipolar?
2) Should I use a chip (ex. L297/298) to driver the motor? Most of them have
a PWM driver, I think it could be more efficient than a simple Darlington
driver.
3) I used a "pseudo-exponential" ramp to accelerate/decelerate the motor.
What curve do I have to follow to reach the best acceleration/deceleration?
Thanks
Marco / iw2nzm