Hello all. I've created a bit of an adventurous project for myself, and I need help choosing the right parts to use, and minorly with configuring them. It will require some backstory, so prepare yourself. Skip to the end for a Tl;DR if you please.
A while back in middle school I competed in a junior solar sprint competition. It's like a mini drag race for solar cars. The idea is you start with a kit including a solar panel, motor, and a few other things, and you make a car that can travel some distance the fastest. I loved the idea, and tirelessly honed mine to perfection. The car went incredibly fast for its size because it was extremely light, with the solar panel making up ~2/3 of the weight. Thanks to the hard work I won first place. For winning, I got the parts to make my own small solar array: 30 1x6 panels that put out 0.5V and ~1 Amp each, plenty of tabbing and bus wire, and a flux pen. Since then, the car has just been sitting on a shelf in a box doing nothing. So, a couple weeks ago I thought why not put it to some use by modifying it so I could remotely control the speed and turning (as for the competition it traveled in a straight line). This turned out to be much more intricate than I previously anticipated. After deliberation and discussion with friends, I decided it would be much less of a hassle to just create a new car using the kit I won.
Now onto the car itself. The goal here is to construct a car that has these basic features: remote speed and directional control, a solar array as the primary power supply, and the lightest weight possible as to increase the speed. For the steering, I've designed a simple lightweight mechanism powered by the smallest servo I could find. For speed control, I thought including a potentiometer between the solar panels and motor was the simplest solution. I'm willing to, despite the redundancy, include a small battery to power these mechanisms as long as the motor's power comes from the solar panels.
The problem here is number three; I have to make the car as light as possible. I'm part of a robotics club at my school, and have worked with motors and servos plenty, so I know how to rig them up normally in this environment where weight is minor. However, since even a few ounces can slow down the car I am consulting you people as to the most efficient way to configure one small servo and a digital potentiometer. My price point is $50 for the parts needed for this, but if needed I can accommodate more from other parts of my budget. The remote part I'll work on once I can figure this out. So far I've looked at the boards sold on this site and some Arduino boards, but I'm new to this field, and was overwhelmed by the possibilities.
TL;DR: I'm building a solar powered RC car. I figured out efficient ways to control the steering and speed, but need help configuring them in a lightweight manner. Once I have that done I'll move on to the 'remote' part.
Thanks for whatever help you guys can provide.