Robot and robot system
A robot includes: a base; and a robot arm coupled to the base. The robot arm includes a plurality of arms having respective joints each of which has a power transmission mechanism. The power transmission mechanisms in the joints have a first reducer of an epicyclic gear type. The power transmission mechanism in one of the joints which is positioned on a farther side of the first reducer is lighter in weight than the first reducer.
1 . A robot comprising:
a base; and
a robot arm coupled to the base, the robot arm including a plurality of arms, each of the plurality of arms having respective joints, each of the joints having a power transmission mechanism, wherein
the power transmission mechanism in a first joint of the joints has a first reducer of an epicyclic gear type, and
the power transmission mechanism in a second joint of the joints which is positioned on a farther side of the first reducer is lighter in weight than the first reducer,
wherein
the first reducer includes
an internal gear having a ring shape,
a sun gear disposed inside the internal gear and coaxially with the internal gear,
a plurality of epicyclic gears engaging with both the internal gear and the sun gear, and
a carrier rotatably supporting each of the epicyclic gears,
the internal gear having higher elasticity than the epicyclic gears.
2 . The robot according to claim 1 , wherein
a gear train of the sun gear and the plurality of epicyclic gears is disposed in a single row.
3 . The robot according to claim 1 , wherein
gear trains of the sun gear and the plurality of epicyclic gears are disposed in a plurality of rows and arranged along a central axis of the internal gear.
4 . A robot system comprising:
the robot according to claim 1 ;
a rack in which the robot is installed; and
a conveyor that sequentially transports a plurality of workpieces,
the robot being configured to continuously process the plurality of workpieces being transported by the conveyor.
5 . The robot according to claim 1 , wherein
the robot arm includes
a first arm coupled to the base via the first joint so as to be rotatable around a first rotation axis, the first joint being one of the joints which comes first from the base,
a second arm coupled to the first arm via the second joint so as to be rotatable around a second rotation axis, the second joint being one of the joints which comes second from the base, the second rotation axis being parallel to the first rotation axis, and
a shaft that moves along a third rotation axis via a third joint relative to the second arm, the third joint being one of the joints that comes third from the base, the third rotation axis being parallel to the first rotation axis, wherein
the power transmission mechanism in the second joint has a second reducer of an epicyclic gear type, the second reducer being lighter in weight than the first reducer, and
the power transmission mechanism in the third joint has a pulley and a belt.
6 . The robot according to claim 5 , wherein
a ratio G2/G1 is in a range from 0.3 to 0.9,
where G1 denotes a weight of the first reducer, and G2 denotes a weight of the second reducer.