Tiny Giraffe (Photopopper Photovore)

 

This was my very first photovore project, as well as my first freeforming attempt. Thanks to the beautiful tutorial created by Chiu, it was a successful first attempt. It uses the standard photopopper circuit, which is basically 2 solarengines hooked together but sharing a common capacitor and solar cell. See schematic below.

 

You'll also notice that the solarcell is on a sort of "neck" to elevate it. (Hence the name "giraffe!") This is to decrease the distance between the light source (a desklamp centred overtop of the "arena") and the solarcell, therby increasing solarcell voltage and current output.

 

According to the competition rulebook, which you can find at the Western Canadian Robot Games (WCRG) website, competitors must fit within a 6 inch cube. I debated whether I should raise the solarcell right up to the maximum height, but I eventually decided against it. Why? Because the only light source for the competition is a desk lamp bent so that the bulb is over the centre of the board at a give height, the farther out and higher you get the dimmer the light. So really, the height of the solarcell is a tradeoff between performance at the outset and performance once the robot gets under the light. (You really have to understand the competition procedures to comprehend this; the picture of this bot in competition below should help a bit.) In addition to the elevation of the solarcell, it is also tilted about 10 degrees forward to help capture light at the start of the competition. It's important to remember one critical rule of the contest: The first robot to the centre gets a half point, while the one closest to the centre at the end gets a full point. Therefore, speed is a key factor in winning.

 

Circuit:	Photopopper Photovore
Sensors:	2 Spring tactile, 2 IR photodiodes
Solarcell:	Panasonic Suncarem 37x66 5.5v
Motors:	Solarbotics Namiki Page Motors