my final year project is creating two autonomous robots, one with an arm that picks an item with a pre-specified location and the other with a box to carry the item and place it at a specified deposit location. right now im at the design stage and i need help to decide which communication technique is the best for the two micro-controllers to communicate, which motion sensors to use to provide feedback signals, how to build the mechanical parts and is it possible to buy these parts ( the 3-axis arm, the dumper box with the pistol, wheels, chassis, and shafts)