This robot has to find a beer can on a table top and then find a shelf then raise the can up till it is on top of the shelf and then drop it.
whew.
the mechanics are in my expertise so i have teamed up with an electronics person to do the electronics part
so here is the start

as shown the lift is done by a single pull of a wire that clamps the jaws first and then starts to lift.
but if the object is heavy the jaws have to clamp harder and so grips the object harder before the lift occurs.
varying the height that the winch draws the wire from varies the tension-clamping pressure and lift of the object
a sort of adjustable clamp lift action that once set stays the same ratio for any weight of object
the base is alloy and can be able to hold any sort of package both mechanical or electronic

the tail wheel used the cut down head from a VCR to support it.
an extremely reliable bearing for the wheel
hmm better reset that wheel baring and replace the ugly bolts with rivetsan afternoon with the electronics friend and the winch to raise the can and the front wheels were added

well we read the rules and have to rebuild the robot to fit in a 270 mm circle so a 5 hour session and a complete rebuild of the robot resulted an a simpler and smaller robot,

all that remains is to put all the electronics in it