I am working on a new low-cost and small robot platform (named Rocka) that, for sake of discussion, can be visualized as a miniature Stingray. (~4" wide)
SMALL OBJECT DETECTION SENSORS:
My original plans were to outfit it's face with a set of Ping sensors or Sharp IR sensors for object detection. However, as tiny as the Pings/Sharps are, they would be driving the size of the robot larger than my intentions. I have looked at the Ping kit with the Servo to use one ping, but the standard size servo would be taller than my goal. I could mount a ping on top of a micro servo, but the videos I have seen give me the impression that having to swing a ping around slows down your robot. (maybe I am being mis-lead by the videos?) I haven't got to the point of adding the IR sensors to my daughter's BOE-Bot, so I don't know how well that truly works as compared to Pings. (My Stingray can travel around the house all day without hitting a single thing or getting itself stuck, so I am impressed with the Pings)
SMALL DRIVE MOTOR METHODS
My original plan for drive motors was to modify some micro sized servos for continuous rotation. After searching a bit online, it appeared that the Naro servo that Parallax sells could not be modified, but I of course had to try it myself. The process went rather smooth, but apparently the pot feedback is necessary for the servo to function, so I killed the one I had. I have found several other micro servos, but cannot find any proof of anyone accomplishing this. From what I have found, it seems to be due to people using small gearmotors and H-Bridges instead for this small of a platform. I am trying to avoid an H-Bridge due to the extra real estate it would require on my platform. I have thought of using a mini breadboard and setting up an L293 H-Bridge on it, but my goal is a "simple" solution. When looking at gearmotors, the prices/styles range all over the place and whenever I find a low cost setup, they require mods or are too large. I can use a standard size servo, but it kills my robots real estate.
Any suggestions for small object detection solutions or drive motors for this size of robot?