Grabber II
This is a beefed-up grabber arm loosely based on the one found on the front of
the RCX 1.5 kit. As shown here I have added a motor to rotate the arm, some angle
sensors and a switch for supplying the RCX with position information and removed
the annoying decoration. It can also be seen that I have extended and strengthened
the uppermost part of the arm. I had found the Lego design quite flimsy and I
thought it would be a good idea to move the motor further back in order to achieve
better balance.
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| Here we can see how I have bettered the lego design by putting support beams
at the outside end of the axles as well as the inside. This means that the top
arm doesn't bounce around like the Lego design
(found here) does. It also puts considerably less strain on components involved
in lifting the arm. Additionaly, the RCX has been moved to the back of the mechanism
in order, again, to balance it better.
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| The use of a switch between the lift-rods and the base of the arm can be seen here.
An axle connects the push-rods to the switch, which is pivoted on the base. The whole
base is mounted on a turret, which allows the arm to rotate through 360 degrees. The
turret is driven by a motor attached to a worm-gear, which is in turn attached to a small
off-centre gear in the hole in the middle of the turret. This novel approach allows the
whole arm to turn freely without requiring any wires connected to a motor which is not
part of the arm.
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