Hello,
I am trying to turn this handle with an Arduino/stepper. It spins 3 3/4 turns. My question is how can I know where the position of the stepper is in relation to those 3 3/4 turns even as the Arduino looses power?
Knob is slightly smaller then a half dollar.
Thanks in advance for any help
The only possibilities are limit (home or end of travel) switches or an absolute shaft encoder, which significantly complicates the project.
You should consider a brushed dc gearmotor instead. They are easier to control, generally more powerful than steppers, and much more efficient. However, you still need limit switches or a shaft encoder to know the shaft position.
Thank you for the reply. The rotary encoder will tell me what position (360 degrees) it is at but since it turns 3.75 times, how do I know which one of the almost 4 full turns that it is on? In other words, I need to keep track of 360 x 3.75 = 1350 degrees of rotation. If the Arduino looses power how do I know what revolution it stopped on?
Most rotary encoders are relative as well. Absolute encoders are a rare specialty.
You could use a multiturn pot. Not best for outside.
Multiturn absolute shaft encoders are available, but would be unreasonably expensive and complicated for a project like this. Consider installing an additional electrically operated valve. On/off are not expensive, no motor required.
When you have built the mounting device for your stepper and designed the connection between the knob and the stepper, you can include something to determine the exact position of the valve. From the picture, you appear to have a tank of some type of gas under pressure.
Have you measured the torque required to completely close and to completely open the valve?
Use a stepper with dual shaft, and attach a rugged multi-turn pot to the rear shaft?
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