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Bell Crank Pitch Booster Mechanism for Robot

IP.com Disclosure Number: IPCOM000038479D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Barrett, MC: AUTHOR [+2]

Abstract

The robot, illustrated in Fig. 1 and Fig. 2, is an electric servo- driven, 6-degrees-of-freedom (plus gripping), cartesian coordinate robot, which is provided with an air cylinder-driven, bell-crank mechanism in order to increase the pitch capacity of the wrist. The air cylinder is driven at a constant pressure with no switching. The pressure to apply to the air cylinder depends on the moment arm applied to the wrist by the end-of-arm tooling and the payload. The torque applied to the wrist by the gripper (and tooling) and the payload, illustrated in Figs.

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Bell Crank Pitch Booster Mechanism for Robot

The robot, illustrated in Fig. 1 and Fig. 2, is an electric servo- driven, 6-degrees-of-freedom (plus gripping), cartesian coordinate robot, which is provided with an air cylinder-driven, bell-crank mechanism in order to increase the pitch capacity of the wrist. The air cylinder is driven at a constant pressure with no switching. The pressure to apply to the air cylinder depends on the moment arm applied to the wrist by the end-of-arm tooling and the payload. The torque applied to the wrist by the gripper (and tooling) and the payload, illustrated in Figs. 3 and 4, is given by

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Tload = WR sin R The torque applied to the wrist by the booster mechanism is given by The torque required of the servo motor to maintain a constant pitch is equal to the difference between the load torque and the boost torque: Tmotor = Tload - Tboost

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The load varies from a minimum when the gripper is empty to a maximum when it is gripping the heaviest item at that station. The servo is capable of servoing both plus and minus some maximum value. Thus, a booster air pressure is selected that causes the servo to drive against the weight of the payload when a heavy load is pitched, and servo against the booster load when no payload is present. Figs. 5 and 6 show the analysis of a specific problem. The gripper applies a maximum moment of 16.5 in-lbs. The end-of-arm tooling results in a load of 2.17 pounds at 10 inches (...