Robot Project !!!

[watzmann]

Hi All ,

i'm building a robot nowadays , but i have a slight problem and need to share it here with you ,

i have a disk with a diameter of 160mm, this disk will rotates and have 10 stations to stop at ,

my problem is :

i'm going to use a stepper motor to rotate this disk , i'm not sure how can i adjust the disk to stop at specifc locations , will i use an encoder ?

or can i calculate the number of turns of the stepper and then send a speifec number of pulses in order to move the disk to a the new location ,

here is a photo for the disk .

Thank you

 

[Hank Fletcher]

Presuming the amount of interfering forces will be close to nominal, pre-determing the required pulses for the desired movement should be adequate. It would be a good idea, and easily employed, to include at least one contact/reset point on the wheel to confirm/reset the wheel position as it passes that point.

If you expect a greater degree of error to effect your system, you might consider an encoder/feedback method that adequately compensates.

 

[watzmann]

o.k , i haven't used encoders before , so i'll fabricate a small one with holles, but what the next step ,

should i use infra red beams reciever and transimeter ,

bytheway i have a photo optocoupler, i think it could be used too ,

what's ur opinion?

 

[Hank Fletcher]

The IR pair is a good start. Before you start fussing with drilling holes in everything, you might try just getting by with the least you can (one hole). Have the transmitter on your wheel near the edge, and have it pass over the the receiver connected to the rest of your circuit. With the transmitter constantly on, as it passes the receiver your circuit will reset/confirm the pulse counts to your stepper.

It's the most minimalist type of encoder system you could have. For greatest accuracy in terms of degrees rotation, just keep the IR pair as close to the edge of the circle as possible.