How to relate PWM with rotating distance in a gearmotor?

Help & Support Robot Parts
1

Hello all,

I’m about to mounting a gearmotor (RB-Sct-687, 12V, 81RPM, 57oz-in) on Actobotics Camera Channel Slider Kit (RB-Sct-530).

Q1:
I like to know the relationship among PWM control, moving distance and speed. How to calculate the linear equation and control it from Arduino board? Any tutorials?

Q2:
Any examples to show reversing the moving direction when the motor reach the end of the rail?

Q3:
Can I extend the length of rail to 10m?

Thanks for your guidance.

2

Q1: Using a motor controller, you won’t be able to link the Speed to the PWM value precisely.
The motor controller will modulate by PWM the battery voltage or input voltage so if that voltage change, the output will change as well.

To get precise rpm, you will need an encoder and/or a stepper motor instead of dc motor.

Q2: First you need something that will tell you the controller you are at the end of the rail. Usually a limit switch. In the controller code you can program to stop and go in the opposite direction after.

Q3: This system can’t be easily extended since the belts are not available in such length.

Here is an article on Instructable talking about an Arduino controlled slider with a stepper motor:

3

Which stepper motor do you suggest to mount on Actobotics Camera Channel Slider Kit (RB-Sct-530)?

Do you carry any rail can be extend to 5m (10m is better)?

Thanks.

4

Unfortunately there’s no specific stepper motor suggestion for that setup - it’s really made to be used with a DC gear motor (with specific mounting).
If you want a stepper motor instead, you may need to create your own adapter plate / mount and adapt the timing pulley to the shaft of the stepper.