$50 robot photoresister question

[pomprocker]

I just used the photoresisters that were listed in the parts like which were 1.62k I believe. I didn't actually do the math that was in the photoresister tutorial. Now when I put the robot in the kitchen where there is light everywhere it just keeps going in circles, it does not go straight. Is this normal?

[goatfish]

i am really sorry ,but i just laugeh when i read thsi,god-dammit now thats gonna happen to me lol.maybe the photoresistors dont thave the same resistance and makes the robot confused

[pomprocker]

I built this guy out of the cardboard box that the digikey parts came in 

I went with the KISS principle for the first time robot here. I will improve on it and upgrade it as I am able to.

This was a lot of fun 

[pomprocker]

anyone have an answer for my first post here?

[airman00]

hmmm

the only thing I could think is wrong is that the photoresistors are not the same values


maybe you should play around with the fudge factor , or the balancing factor.

What the fudge factor is is the amount of accpetable difference. Like say one photoresistor has a value of 12 and the other ahs 22 under the same light.

So a fudge factor of + - 10 will say if the values are within 10 from each other , they are considered equal , so 12 and 22 are considered the same. 

[superchiku]

take a look at the fudge factor and the 50$ robot's resistance value was based on the admins's calculated values

urs may be different so u should have calculated it...

also photoresistor may be cheap but certainly not the best try to use IR or other sensors like sonar etc on ur bot

[pomprocker]

I haven't learned how to implement IR or Sonar yet 

[airman00]

@superchiku

He is using  photoresistors to detect light levels not for obstacle avoidance


@pomprocker

did my advice work?

[pomprocker]

haven't gotten a chance to play with it yet, im pretty busy during the week.

I don't know how to play with the "fudge factor" anyway.

[ed1380]

Ive had the same problem. for a long time i thought my servo was mesed up while i was modding it, cause i resoldered the pot for sore resistors.

how would we go about changing thing fudge factor. what is it called in the source code?

[Admin]

So lets say the left photoresistor reads 10 points lower than the right even in the same exact light.

This means the left pr needs some fudging . . .

Code: [Select]

int fudge_factor=10;//left pr is whack, 10 points too low
left_photoresistor = adc(0) + fudge_factor;//read value and fudge it up
eat_fudge();//mmmm, robots like to eat fudge!


[airman00]

So lets say the left photoresistor reads 10 points lower than the right even in the same exact light.

This means the left pr needs some fudging . . .

Code: [Select]

int fudge_factor=10;//left pr is whack, 10 points too low
left_photoresistor = adc(0) + fudge_factor;//read value and fudge it up
eat_fudge();//mmmm, robots like to eat fudge!


I actually made up my own word for fudging it. I call it sensor biasing.