# Localize a Mobile Robot on a Mirror

I am currently busy with a project which requires me to construct a robot capable of cleaning a heliostat (movable mirror used to redirect sunlight). Heliostats are basically large flat mirrors that track and reflect the sun. In order to be cleaned, the heliostats would be stowed in a horizontal position so that the robot may drive over its surface.

My question is then how or what sensors would i use to localize the robot on the mirror. From what i have seen many robotic sensors are unable to effectively detect glass, which seems to be a problem as the systems only real reference is the mirror. I am considering using a type of cliff sensor similar to the ones on robotic vacuum cleaners, but how would i localize the robot when its in the middle region of the mirror? Will the cliff sensors and wheel odometers be enough to fully localize this robot or not? i.e. What sensors would work?

I have attached both a basic image of the robot as well as an image of a typical heliostat the robot will need to clean. Mirror sizes may vary but this size is roughly 1m x 2m Please let me know if i must provide more information to clarify the question.

• If you‘re aware of the exact dimensions of the mirror, you can easily localize much the same way you would find the center of a circle using Euclid methods. See ‚The Elements‘ book for countless examples of solving geometry questions when knowing only geometric references. – morbo Oct 3 '19 at 16:57
• Thank you morbo, I will take a look. The size of the mirror is definitely known, so i will look into these methods. – SupanovaZA Oct 3 '19 at 19:55
• Why do you need to localize yourself? Just bouncing around randomly might be fine... What level of accuracy do you need? – Ben Oct 4 '19 at 12:42
• Hi @Ben. I would like to be as accurate as possible, the idea is to try clean as many mirrors in as little time as possible, or to be as efficient as possible. I think accurate navigation can save alot of time. – SupanovaZA Oct 4 '19 at 21:20
• Hi jsoltola. It seemed the question was lost into the depths of the website and didn't receive quite the answers I was looking for, so I thought I'd try again. Won't do it again though! – SupanovaZA Oct 4 '19 at 21:21