This is my first attempt at making a robotic arm by myself (I built one from the instructions on legomindstorms.com, but I've never made one myself, until now).

This is the "Prototype A". I originally planned to make many prototypes, but this one turned out so good I think all I need to do is make slight modifications to it.

It has a five axis rotation, powered by five motors, (four "normal" and one micro motor, for the rotation of the claw).

The claw itself is pneumatically powered.

The arm is not finished yet, the base and the arm itself has been built, but the arm has not been attached to the base, and the compressor/switch system for the pneumatic claw is not built yet.

The arm will be powered by two RCX units when completed, using six motors in total, and two sensors (one light and one rotational).

Here follows a description of each image.

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aftercords.jpg - This is the arm itself, with all the cords and pneumatic tubes attached to it.

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arm1.jpg - The arm, from another angle, before the cords and tubes were attached.

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base.jpg - This is the rotating base. The arm will be attached to the grey turntable, along with a motor enabling an up/down-motion.

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baseunder.jpg - The base, viewed from below. You can see the motor, and the system used to gear it down.

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claw1.jpg - The claw! Only one cylinder is used (because I only had one).

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clawfront.jpg - The claw, viewed from the front. You can see the light sensor placed above the claw (used to get light readings from grabbed objects), and the two cogwheels, necessary to make the claw open and close right. If I had used two pneumatic cylinders, they wouldn't have been necessary. Because of them, the claw can not be entirely centered, but it's not a big difference.

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closerotation.jpg - A closeup of the wormgear box, used to make the turntable at the base turn.

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cogbase.jpg - Sideview of the base, where you can see the cogwheels that connects the motor with the wormgear above.

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mechanism1.jpg - This is the mechanism used to provide up/down roation in the "elbow" of the arm. The motor powers the wormgear. The cogwheel under the wormgear is "locked" to the other part of the arm (the one that connects with the rotating base).

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mechanism2.jpg - Shown here is the system used to gear down the up/down motion of the claw. The black turntable to the left rotates up and down. You can see the red micromotor inside the turntable, that makes the claw spin around.

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rotate1.jpg - A closeup of the claw, and the turntable that rotates it. The claw can move much like a human hand (open/close, up/down, rotate), and I'm a bit proud of this achievment. This was the part I thought would be the hardet, but it turned out rather easy! The red brick is the micromotor. Unfortunately, I have no more pictures of this, so I'll try to explain it in words. In the center of a big turntable, are teeth. You can put a cogwheel between those teeth, and if you connect the cogwheel to a motor, you can spin the lower part of the turntable, by turning the motor on. This is what I've done, and to preserve space I used a micro motor. The cogwheel itself is not visible, but you can see a small part of it, at the left edge of the turntable.