Robot Grippers

Understanding Various Types of Grippers End-of-arm tooling (EOAT) encompasses a variety of grippers used in robotic applications. These include vacuum, pneumatic, hydraulic, and servo-electric grippers—each with unique mechanisms and purposes. Vacuum grippers use suction to lift objects; pneumatic ones rely on air pressure for gripping; hydraulic versions utilize oil pressure for heavy loads; while servo-electric models offer precise control through motorized adjustments suitable for delicate items.

Applications and Mechanisms Behind Gripper Designs Gripper designs cater to specific tasks: vacuum systems handle irregular shapes using soft materials like sponges; pneumatic grips are ideal for smaller robots due to their simplicity with compressed air operation. Hydraulic tools manage high-weight objects by combining strong grip force with stress-relief springs. The simplest design is the pinch or cord-based mechanism that opens/closes claws via tensioned cords controlled digitally or analogously by motors.

Rack and Pinion Gripper Mechanism The rack and pinion gripper mechanism operates through a straightforward mechanical process. A toothed straight wheel, or rack, moves in and out via an actuator at the back, causing two side pinions to rotate for opening or closing the grippers. The actuator can be controlled digitally by motors or pistons; when pushed forward by a piston or lead screw system driven by motor rotation, it adjusts the position of the rack analogously. This simplicity makes it versatile for various applications.

Vacuum Grippers: Advantages and Limitations Vacuum grippers use suction cups arranged circularly to lift objects with vacuum pressure created between them and surfaces. While effective in manufacturing pick-and-place tasks due to their flexibility, they face challenges like leaving marks on sensitive materials from high-pressure contact points. Custom designs are often required per object type; inconsistent compressed air levels may reduce reliability during heavy lifting operations leading potentially to dropped items if not handled gradually with soft acceleration/deceleration movements.

Vacuum grippers designed for uneven-shaped parts utilize soft, spongy materials instead of traditional polyester or polypropylene vacuum cups. The process involves the gripper descending onto an object, enveloping it with the sponge material before initiating a vacuum to secure it tightly within. This method allows effective handling and pick-and-place operations even for irregular shapes like rectangles, cylinders, and spheres. For cylindrical objects specifically, internal adaptors shaped to match their diameter enhance stability during lifting.

Pneumatic grippers operate similarly to hydraulic systems but are designed for lightweight tasks in confined spaces. They use low air pressure, making them ideal for small robots with limited work areas. Different types of pneumatic grippers exist; some close when air is applied (positive mechanism), while others open under the same condition (negative mechanism). These devices offer an excellent grip-to-weight ratio, requiring minimal force to handle desired weights efficiently. Their compact size and cost-effectiveness make them suitable for applications needing small compressors.

Hydraulic grippers generate significant force, enabling them to lift heavy objects. The strength depends on the piston's diameter and the ratio of forces applied. By pressing oil at high pressure into a piston, these grippers amplify force for closure; increased pressure results in tighter grip. They operate with one input nozzle for oil inflow and another output nozzle to release it when opening is required.

Servo-electric grippers operate using electric motors, which are controlled through a sequence involving user input commands. The motor's rotation is monitored by an optical encoder that provides feedback on its position and degree of movement. This system includes a control unit to manage the process: first teaching or programming the motor externally, then sending commands to activate it via a gripper controller connected with positional sensors. These components work together to rotate gears for opening and closing actions in an analog manner.