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Is the TSL1401 too much for my job?
After reading the details of the Parallax
TSL1401 Linescan Imaging Sensor Daughterboard
it seems like overkill. All I want to do is detect that my BOT is pointed at the brightest light in the room. A simple light detector like is used to follow a black line on the floor should be good enough.
Suggestions?
Ken
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Take a look at the QTI Sensor on the Parallax site...only 6 bucks, emits and receives IR to follow line.
But I'm not sure if you want to follow a line or seek out a bright light??????
John
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I want to seek out a bright light.
John,
I only mentioned the follow-a-line to indicate how simple my needs are. The $50 sensor has great pattern recognizing capability. All I need is something to attach to the front of the car which can tell it that it is going in the right direction. If this device had a lens that would be the best design. If it had a reasonably narrow lens angle then once the BOT found the light, it could stay well directed.
Ken
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Ah OK got it.
The problem with a simple light detector and lens is that it gives you no positional information as to where to go to seek higher intensity. The linescan sensor you mentioned does due to its pixelated imager...but as you say expensive.
One thing I did similar to this was to mount the detector on a servo that can scan left to right and back. I issued position commands to the servo, then read in the ADC value of the sensor, moved the servo, recorded data, etc. The servo positions were mapped to the forward axis of the truck. A steering correction could then be calculated. Only a few positions are needed to determine if you need to turn to a higher intensity direction, but you need to oversample to filter out noise. Make your steering correction, then start a new scan. You may need a digital filter on the corrections so that you don't oscillate around the proper direction.
You can always buy a smart sensor, but why not make a simple (cheap) one and make it smart with your processor? Also more of a learning experience.
Just a thought.
John
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I figured I could steer the car....
John,
My thought was that my light detector would be on the front of my car. The servo searching capability could be done by steering right and left just a little bit. This way the car goes directly to the light.
I imagine that once it gets there, the student operating he RC transmitter will be able to see it and retake control. These things go way fast under RC control. I image it creeps when autonomous.
Make sense to you?
I am having a difficult time figuring out what Basic Stamp starter kit is the best for me. I am USB oriented. I am guessing that I should spring for the 160 bucks for the BASIC Stamp Discovery Kit - Serial (With USB Adapter and Cable)
Your thoughts please. I'm going to bed now. It is eleven o'clock out east.
Ken
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Just read you last post
I figured that the very first thing the car would do once under autonomous control would be to make a 360 degree circle. Somewhere in that circle it would be facing the light bulb. That should do it.
Ken
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Steering to find the source might not converge, but that is part of the fun so try it see what happens.
Dave recommended the PICKIT2 from MicroChip and buy PicBasic compiler. If you know C, you can download a free compiler from MicroChip. I had mentioned the pros and cons of starting with PIC or going to Basic Stamp (ready to go, free compiler, but expensive and one chip/project). Looks like you decided on Basic Stamp.
I would recommend the USB version of whatever you buy. Fewer computers, mostly laptops, have a real serial port.
As I said, I got limited by the number of variables and to some extent the code space on the Basic Stamp. It was a good learning platform, but I eventually went the PIC route, much more flexibility. If you stay in the game and get more complex, you will probably end up migrating to a PIC.
If you go Basic Stamp, USB Board of Education or similar is a good basic system.
You may want Dave to weigh in and see his thoughts.
There is no unique answer.
John
Last edited by John_Mac; - 18th November 2009 at 05:44.
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I am not up on the basic stamps (SX,propeller), been several years ago that I last played with them. Do they have ADC (Analog Digital Converter) now?
If you go with something like the 18F4550 you have 13 ADCs and it can run at 48Mhz with a 4Mhz external OSC.
Language --- C, ASM, a flavor of Basic??? Of course I am in favor of PBP. It is pretty much bullet proof and the support can not be beat.
How to make an algorithm for automation??? I suppose everyone has their methods but I will study how a human does the task (a large part of my work is automating existing machinery) and go from there. If I find something to make it all more efficient but not something that the humans are doing for whatever reason (360 viewing ?) I will consider a change in the procedure.
It will be interesting to see what the students come up with...
Dave
Always wear safety glasses while programming.
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Three photo-resistors set 30 to 45 degrees apart (one straight ahead)with a little shielding on each.
Dave
Always wear safety glasses while programming.
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One thing you will need to do at the start is "global" scan to find the light to start with. It may or may not be in the limited forward acceptance of a detector array. So maybe a 360 azimuth array? or a forward and backward detector on the servo I described?
Kinda depends on the number of input channels are available for this specific function.
John
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