pic16f877a with metal detction

hi to all,
i am doing my final year project on pic based robot for bomb detection and defusion in military applications....but for demo purpose i select metal detecting sensor or some material to detect any metal near to robot vehicle and it must activate the motor connected with robotic arm to pick and lift the object from that place...i m using pic16f877a with rf txr and rxr(tws & rws 433)
robot vehicle consists of four motors:
2 for wheels for moving front ,back
2 wheels for robotic arm(for picking and lifting)
1.can you please suggest pic coding to detect and trigger the motor to lift up?
2. also whether i can use metal detecting sensor or simple inductor os any snsor to detect the presence of metal?
3.ple suggest coding for that purpose please urgent and i have few more days to submit with full implementation

i did this project a year before
it was robot to detect mine using inductor
The inductor was a turned around a circular shaped cartoon and when the inductor is close to the metal the inductance changes with some processing i can get 1 or 0 from it to indicate to micrcontroller that there is a bomb the robot then take decision to turn around this bomb and while turning a powder box is opened so that there is a half circle around the bomb indicating it's place

you give the robot the area that it will make scan to it like saying to robot (from this place you are in begin to scan area 10*10 meters)
you may give it using LCD keybad
then it start to scan
and you must choose a scan technique
like fig1 and fig 2 attached (sorry iam not good in painting)
in fig1 you take roads like painted but take care to length and width of them and your robot also
in fig2 it is more sophisticated

finally you can have another LCD (Graphical one)
with highlighted pixels at positions where the bombs found and with written dimensions from the start point (x,y)


Mahmoud

thank you so much sir for ur help...
but due to shortage of time i can t go for tat scan technique....i accept ur inductor concept...but will u pls give circuit diagram for pic16f877a with inductor in conjuction with l293d(motor driver )circuit or just pic16f877a with inductor to run arm with 2 dc motors for lift tat meal and pick,.....coding and circuit diagram is a very big problem for us yar?pls help me....