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Herbert 1701 Species C Generations 4 - 6 Builds

I want to start off by apologizing for an inaccuracy in the Herbert 1701 Species C schematics. I had grown so accustomed to using reverse biased LEDs as photo sensors that I placed the photodiodes in a reverse biased position in all of the schematics. This, of course, is incorrect as photodiodes function in a forward bias position. The charge circuit for Herbert 1701 Species C Generation 6 is correctly biased as it makes use of an infrared LED instead of a photodiode and should remain reverse biased. All of the affected schematics have been updated to fix this screw-up on my part.

Moving on, I have been building out each of the three species C robotic life forms, generations 4, 5 and 6. Although I will not be labeling each as a separate generation, there are many aspects of the mechanical build that are subject to the same evolutionary process that I have been following for the circuit designs. Use of different components and their placement have just as profound an effect on the effectiveness of each Herbert as the initial circuit design, even more so in some instances. Just as with the trial and error used in those circuit designs, the builds have required much redesign and tweaking.

Beginning the design phase, I had decided on an outer shell to hold the various sensors and solar panel in place. I produced this outer shell using a two piece mold process, which will be used for the depictions in the upcoming tutorial. While this design seemed like a good idea in principle, the application left a lot to be desired. Herbert 1701 Species C Generation 4 was the guinea pig for this design and would have likely yelled at me for my idiocy if it were capable of such.


Utilizing this initial build design, I was able to learn a lot about not only the mechanical aspects of these robotic life forms, but also limitations in the electrical circuitry. The first thing I learned is that mechanical engineering is not my strong suit. The second is that an outer shell becomes too cumbersome for a robot that has limited energy resources. Lastly, in a world where the Herberts would be fighting for the best light source, as in a photovore competition, tactile sensors turn the little fellows into complete wimps. This last part is important, as it will be leading into future generation designs (Yes, the schematics are already finished for such. No, they will not be posted until the other kinks in mechanical design are worked out).

Following the above lessons, Herbert Species C Gen 4 received an overhaul. Not only did I remove the outer shell, but the tactile sensors as well (that rhymes). Additionally, the photodiodes have been moved to the bottom of the circuit board to reduce the amount of blinding, or sensor flooding, that occurs (i.e. too much light hitting each sensor so that it doesn't know which side has more light). The result is build #2 depicted below.

Generation 5 was built out identical to generation 4, with the only difference being the actual circuit design. For Herbert Species C Gen 6, the solar panel required repositioning to the front of Herbert to prevent obstruction of the light level sensor in the charge circuit (i.e. the IR LED). I also darkened the area above the photodiodes using electrical tape and placed a divider between each sensor. The results of generation 6 up to this point follows, with these additional changes flowing back to the other two generations.


There will be additional changes to come in these builds, such as blackening the sides of the directional photo sensors, trying out different photodiodes (I have several different parts to try), and, most importantly, moving the motored wheels all the way forward to provide for better weight distribution. For the purposes of testing each species for the natural selection process, these changes seemed irrelevant and will wait.

I performed several tests with each of the generations. The first was a speed test, similar to a solar roller competition. In full sunlight on a flat level surface, generation 4 won out over the short distance of 1 1/2 feet. Its quick charge rate up to 3 volts and efficient energy design kept Herbert rolling along. Generation 6 was a very close second, despite charging to over 6 volts in full Florida sunlight, this generation will continue to run down to a very low voltage (around 1.5 volts) giving it a slower start but continuous stride throughout.

The second speed test was performed over a slightly longer distance of 3 feet, where the clear winner was generation 6. Generation 5 beat out generation 4 by a slight margin, showing that once it had charged fully the first time, subsequent recharges occurred faster and the extra energy allowed for a quicker distance running Herbert.

The next speed test was performed over a 2 foot length on an uneven surface: the walkway in my backyard. About one foot of the test was on a relatively smooth sidewalk, with the second half moving onto a very uneven stone paver. There was a slight gap, about 1/2", between the two surfaces. Again, generation 6 was the victor in this competition. Generation 4 did not finish as it lacked the power to clear the gap between surfaces and instead stalled out at that point.

The last speed test took place near a window indoors on a rainy day across a smooth surface. This test actual took place quite by accident, but brings home the differences between generations. Herbert 1701 Species C Generation 6 was the only generation to start or finish this competition. In the very low light conditions, not even the low voltage generation 4 was able to build up enough of a charge to get moving, whereas generation 6 happily popped along at a rate of about 1 inch per 3 second interval. On a whim, I performed the same light level test using a photopopper from Solarbotics. As with generations 4 and 5, the photopopper never got moving, even with the very low trigger level of the two Miller Solar Engines.

The last competition is the photovore competion, which I will not be running until all mechanical tweaks have been tested. Just to note, in an actual photovore competition each robot is allowed twice the solar panel surface area as is currently in use (read: two solar panels instead of one), but in testing apples to apples I believe one solar panel will show clear results. I will also be throwing the above mentioned Solarbotics photopopper into the arena to provide four competitors total and a good control robot.

So what did we learn from all this? Number one is that I suck at mechanical design and will continue to tweak out and retest the Herbert Species C critters until I am satisfied. The second thing is that the variable charge level of the Max8212 solar engine seen in generation 6 is superior to the set charge level seen in the other two generations, and even the set charge level of a standard photopopper using Miller Solar Engines. At this point it seems obvious to me which generation should progress forward along this particular branch of the evolutionary cycle that is Herbert 1701. Of course, the photovore competion will be the final word in the natural selection process. Stay tuned.


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