need help with line sensor

[aruna1]

hello,i'm want to make a fast line follower robot that will work under high ambient light condition (outdoor). i have 3 options to make line sensor: using ldr + led pair , or using simple IR emmiter detecter pair or using tsop1738 + 38khz IR. So can someone please help me to choose suitable sensor for line sensor? if there is anyway to make a sensor that will self adapt to environment? (some thing that will work on both bright sunlight and a dark room without manually adjusting sensors) thanks.

 

[Vizier87]

The simplest is the LED and LDR pair, using comparators. I don't think ambient light had much influence on the system, the setting on comparator needs to be set properly though.

 

[aruna1]

i was thinking about using analog values,coz if i use a compartor and get a digital value i will have to adjust threshhold value everytime environment change significantly

 

[Vizier87]

there are analog solutions too, but you need to process the analog data properly by profiling them thru a uC. A comparator can easily be modified into an amplifier, see datasheets on op-amps, you can have a nice range of outputs with respect to ambient light.

 

[aruna1]

can you give me some pesudo code for processing analog input to remove ambient light and then use processed signal to follow the line? i'm really interested in some adaptive algorithm that will work regardless of ambient light variation. and by the way are ldr suitable for fast line following work on analog readings? heard they have pretty slow responce time. thanks

 

[Vizier87]

I'm not a code guy, I'm more into analog electronics. Anyway, if you're building the system by yourself, you'd want to write the code yourself, so that you can troubleshoot it properly according to your construction.

LDRs are good enough for protos, you're not running them like real fast, right? The response of comparators towards the change in the LDRs are fast, build it yourself and you'll see.

Start with this: LM358, download the datasheet, and build the circuit for comparators. You'll be asking less if you built it first.
Here's the circuit:
**broken link removed**

 

[aruna1]

I'm not a code guy, I'm more into analog electronics. Anyway, if you're building the system by yourself, you'd want to write the code yourself, so that you can troubleshoot it properly according to your construction.

LDRs are good enough for protos, you're not running them like real fast, right? The response of comparators towards the change in the LDRs are fast, build it yourself and you'll see.

Start with this: LM358, download the datasheet, and build the circuit for comparators. You'll be asking less if you built it first.
Here's the circuit:
**broken link removed**

i have built a digital version before.as you said it worked well (was checked indoor).and was wondering what to use if i want to make it adaptable to environment.
thanks