Testing the whiskers

mj37

I have a question regarding the information on·page 171 on chapter 5 of Robotics with boe-bot book. When I measure the voltage between pin P5 and Vdd (see diagram 5.7) the reading is 0 volt and when I press the whisker the reading is 5 volts. However the book says just the opposite. Can someone explain what am I doing wrong? ·
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BTW, I have assembled the whiskers and they are working fine.
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Thanks
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Melissa

Andy Lindsay (Parallax)

Hi Melissa,

If you are measuring between P5 and Vdd, you are measuring the difference between P5 and 5 V. The book is describing measurements with reference to 0 V for the system, which is Vss (commonly called "ground"). Connect your voltmeter's (-) or (GND) probe to Vss, and the (+) probe to P5. Repeat your measurements, and they should match what's described in the book.

Regards, Andy

mj37

Thank you so much. That worked and I understood. I am now working on the infrared chapter now. Are there any exercises (circuit exmaples) that use whiskers, photoresistors and the infrared all together? Thanks
Melissa

Andy Lindsay (Parallax)

Excellent. As for applications that incorporate all the circuits, I haven't seen any published examples. That's your challenge, to build a Boe-Bot that can exit a dark room with the light streaming in through a doorway. The Boe-Bot should navigate around obstacles with infrared. Some black obstacles absorb infrared, so much so that the Boe-Bot's IR detectors cannot see them. That's where the Whiskers come in, to sense such objects by contact, and then the program can make the Boe-Bot navigate around them. Variations on this can be done with an electrical tape delimited course which can be followed with the QTI Line Follower AppKit <http://www.parallax.com/detail.asp?product_id=28108>.

After continuing through IR Remote with the Boe-Bot <http://www.parallax.com/detail.asp?product_id=28139>, an interesting demo Boe-Bot would be one that you can configure to perform different functions (whiskers, photoresistors, IR) with your remote. Also, if you are simply driving the Boe-Bot around with the remote control, you can add features that make it self preserving. By the time you are done with IR Remote for the Boe-Bot, you will be able to add artificial intelligence that causes the Boe-Bot to deal with obstacles and override instructions from the remote that might otherwise cause it to run into said obstacles. You can also add features that make the Boe-Bot avoid dark places or bright lights (again superseding navigation instructions that you send it with the IR remote).

These are just a couple ideas; there are certainly many more applications. If you come up with one you think is interesting, by all means post it here.

IMPORTANT. Use electrical tape to cover the segments of the whiskers that might come into contact with other circuits. Of course, don't cover that part that comes into contact with the 3-pin headers, but cover everything else that might possibly touch the IR or photoresistor circuits.