Good idea, but this calls for another level of robotic articulation.
Perhaps a fly around robot with a vacuum cleaner style of suction
mechanism, pulling stuff into heavy duty plastic bags could do the
trick.
A vacuum cleaner for solid debris...
....in a vacuum!
Priceless!
Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K.
http://www.fleetie.demon.co.uk