Gripper (Claw) for Small 2×2 & 2×4 LEGO Bricks
Here's a Gripper for Small LEGO Bricks I've developed for a larger project. It is designed to pick-up standard 2×2 and 2×4 LEGO Bricks. The gripper is opened and closed via a LEGO® Power Functions M-Motor with a 24-tooth Clutch in the drive train to take care of the need for limit-switches and encoders.
Complete Gripper Assembly for Small LEGO Bricks
Besides the LEGO® Power Functions M-Motor which controls the jaws, a second motor attaches to the 'Yellow Axle Extender'. This motor is used to lift the Jaw Assembly up and down onto the target block.
The 'Lime Green' parts shown above is the mount for an LEGO® RCX Touch Sensor, which I chose for it's compactness. This LEGO® RCX Touch Sensor is used as the 'Limit Switch' when raising and lowering Jaw assembly.
Close-up of Gripper Mechanism
Each Jaws of the Gripper is driven from a Worm Gear attached to the axle. rising from the centre. At the ends of each jaw are fingers composed from 3x Rubber Technic, Double Flexible type Axle Connectors. Using the rubber Axle Connectors in this manner insures flexibility, which gives the jaws excellent gripping capabilities.
As configured here, the Jaws don't close as quick to meets some needs. When the 24-tooth Clutch and 8-Tooth Gears are interchanged, the resulting speed of the Jaws opening and closing is equal to the speed of a pneumatic system. The LEGO® Power Functions M-Motor has only to be engaged for a second or so for the Jaws to change state.