A while ago I have tested if suction cups of naminukas are strong enough for hanging from plaster board ceiling. Answer is yes, but I didn't make any decent video showing that because any mistake which could result in robot falling from ceiling height would most likely result in £1000+ of broken parts. Since I think it is quite an impressive capability and also end goal to make robot safely traverse most of indoor places I risked to make a small demonstration on top of the bed:
To make more sophisticated activities than just turning safe, I need to improve sensing if suction cup of one leg reached sufficient vacuum level before lifting other feet. On the ground inertial measurement unit is sufficient to detect if leg was stuck to surface or not as explained in Detecting carpet blog entry. Such solution is not an option on wall or ceiling. Most obvious solution is to add pressure sensors to each feet. That is on my list to explore. There are few indirect measurement alternatives:
- Infer if required vacuum level is reached by trying to lift a leg and observing servo motor current. Depending on vacuum level it would be easy or hard/impossible to lift a leg and motor current would reflect that. This would be the most desirable solution as it doesn't require any new hardware therefore doesn't add any weight or cost.
- If you don't mute my videos with horrible noise you probably noticed that noise changes when foot is up and vacuum pump just sucks the air and when foot is down and vacuum is being generated. I am planning to add webcam with a microphone to robot in the future. This could be a great opportunity to try some machine learning for mapping noise to pressure.