sharping pencil robot design!! need help

[acpnor]

hai..
my situation :

1. the motor will running automatically when the dull pencil get in to it. and it will stop when its already sharp.

2. the motor will not running if the sharp pencil get in to it..

so the problem is..i dont know what kind of sensor to use.... please help me..

[yonghui]

hi,

if u know this type of sharpener.
http://i3.squidoocdn.com/resize/squidoo ... harpener_2

i think u can detect whether the pencil is done being sharpen by detecting the load.

when the pencil is sharper, it becomes very easy to turn the sharpener handle.

so, when the current through the motor drop to certain level then probably the process can be considered done.


rgds,
yh