Project Log

November 25th, 2003: Lab Day 5

Where: Jobst 248

What got done:

The lab day consisted mainly of research. It is still unclear how much power we can expect from the solar cells. The difficulty is we do not know exactly how much energy is radiated from a standard florescent light bulb. We also don't know what range of frequencies they produce. Working with energy densities from the sun will not provide an accurate picture of what we can expect inside. The numbers for current out of the panels is unexpectedly high, which leads us to believe our initial calculations are flawed in some way. We are still studying solar technology and are starting to figure out all of its nuances.

On issue of drive, allot more research has been done. Initially we had thought an open loop electric motor would serve our drive purpose nicely due to the motors relative light weight and low current requirements. Then the issue of control was brought to our attention by our advisors. How would we control a specific number of revolution on a single wheel to make an accurate turn? The initial solution was to use a stepper motor for its intrinsic control ability. It would also allow us to regulate speed if we desired. The downside to this idea is that stepper motors weigh almost double what standard electric motors do. Also their current draw is much larger than their standard counterparts. The biggest downfall of all is that fewer companies manufacture such motors. It has been quite difficult for us to find motors that meet our requirements. Upon talking to our lab director he suggested that we use some sort of encoder to add a control element to a a standard motor to get the best of both worlds. More study needs to be put into these encoders to see if this idea if feasible.

What needs doing:

What needs doing is pretty much the same as it was last week. We are still not confident on the amount of energy we will have to work with. We will need to find more information on how the florescent lights work. On the motor end there are various encoders that work with standard electric motors. It will have to be determined if such encoders will work for the task at hand. If so then we will need a comparison between the stepper and standard motors with all of their required equipment. The best out of that will be chosen and ordered.