US 7,028,578 B2Granted

Wrist driving mechanism for robot

AssigneeFanuc Corporation

InventorsMasaaki Uematsu, Kuniyasu Matsumoto, Hiroshi Nakagawa, Masahiro Morioka

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Abstract

A wrist driving mechanism capable of arranging a large amount of cables and pipes in a robot arm. A robot wrist mechanism having three degrees of freedom is driven by first, second and third drive shafts for transmitting driving forces of first, second and third motors M4, M5 and M6, respectively. The first drive shaft is a hollow shaft for transmitting a rotational driving force from the motor M4 to a first wrist element supported rotatably around the first axis B1. The second and third drive shafts are arranged eccentrically with the first axis B1 in an inner space of the first drive shaft. The second drive shaft transmits a rotational driving force from the motor M5 to a second wrist element supported rotatably around the second axis B2, and the third drive shaft transmits a rotational force from the motor M6 to a third wrist element supported rotatably around the third axis B3. A first gear and a third gear as planet gears and a second gear and a fourth gear as sun gears are provided for avoiding complication of structure due to the eccentric arrangement of the second and third drive shafts.

Claims8

Dependent claims

A robot wrist driving mechanism for driving a wrist mechanism provided at a distal end of a robot arm and having three degrees of freedom around first, second and third axes, comprising:

a mounting base concentric with the first axis;
first, second and third motors mounted to the mounting base;
a first wrist element supported rotatably on said mounting base, concentric with and rotatable about the first axis;
a hollow first drive shaft for transmitting a rotational driving force of said first motor to said first wrist element, relatively to said mounting base;
a second wrist element supported rotatably on said first wrist element around the second axis;
a second drive shaft connected to said second motor and arranged in and extending through an inner space of said first drive shaft, eccentrically with the first axis, to transmit a rotational driving force of said second motor to said second wrist element, to rotate same about said second axis relatively to said first wrist element;
a third wrist element supported rotatably on said second wrist element, concentric with and rotatable about the third axis;
and
a third drive shaft connected to said third motor and arranged in and extending through the inner space of said first drive shaft eccentrically with the first axis, to transmit a rotational driving force of said third motor to said third wrist element to rotate same about said third axis relatively to said second wrist element.

6 more elements

Dependencies are inferred from the claim text.