Robot having high stiffness coupling
View Patent ↗A substrate transport arm including a plurality of links rotatably connected to each other in series; and a system for maintaining radial orientation of a third one of the links regardless of a rotational angle of first and second ones of the links relative to each other. The system for maintaining radial orientation includes a four-bar linkage.
1. A substrate transport arm comprising:
a plurality of links rotatably connected to each other in series;
a system for maintaining radial orientation of a third one of the links regardless of a rotational angle of first and second ones of the links relative to each other, where the system for maintaining radial orientation comprises a four-bar linkage connected to at least one of the plurality of links, where the four-bar linkage comprises a rotatable carrier pulley rotatably mounted to the second link, where a band connects the rotatable carrier pulley to a shaft at a joint of the second link to the first link, where a drive pulley is fixedly mounted on the shaft, and where the band extends between the rotatable carrier pulley and the drive pulley, where the drive pulley is located inside a loop formed by the band, and where the four-bar linkage is mounted on the second link.
2. A substrate transport arm as in claim 1 where the four bar linkage comprises a quadrilateral linkage have four rotating joints.
3. A substrate transport arm as in claim 2 where the quadrilateral linkage comprises a parallelogram linkage.
4. A substrate transport arm as in claim 2 where the quadrilateral linkage comprises a convex quadrilateral linkage.
5. A substrate transport arm as in claim 1 where the third link comprises an end effector, and where a member of the four-bar linkage is a wrist rotatably connecting the end effector to the second link.
6. A substrate transport arm as in claim 1 where the rotatable carrier pulley is on a first end of the second link, and where the four-bar linkage comprises a rotatable wrist on an opposite second end of the second link, and two bars having first ends rotatably connected to the rotatable carrier pulley and second ends rotatably connected to the wrist.
7. A substrate transport arm as in claim 1 where where the system for maintaining radial orientation comprises a drive ratio of 2:1 between the shaft on the first link and a wrist connecting the second link to the third link one of the links.
8. A substrate transport arm as in claim 1 where the four-bar linkage comprises a wrist member rotatably mounted on the second link, where the third link is fixedly connected to the wrist member, and where two other members of the four-bar linkage are rotatable connected to the wrist member.
9. A substrate transport arm as in claim 1 where the four-bar linkage is completely supported on the second link.
10. A substrate transport arm comprising:
a plurality of links rotatably connected to each other in series, where the plurality of links comprise a first link, a second link and a third link;
a four-bar linkage connected to at least one of the plurality of links, where the four-bar linkage comprises a carrier rotatably mounted to the second link, a wrist member rotatably mounted to the second link, and two bars connecting the carrier to the wrist member, where the two bars have first ends rotatably connected to the carrier and second ends rotatably connected to the wrist member, and where the wrist member at least partially connects the third link to the second link,
where the four-bar linkage and a connection of the four-bar linkage to the first link are configured to maintain radial orientation of the third link relative to the first and second links regardless of a rotational angle of the second link relative to the first link, where the carrier comprises a rotatable carrier pulley rotatably mounted to the second link, where a shaft is provided at a joint of the second link to the first link, where a drive pulley is fixedly mounted on the shaft, where a band connects the rotatable carrier pulley to a shaft at the joint of the second link to the first link at the drive pulley, where the band extends between the rotatable carrier pulley and the drive pulley, and where the drive pulley is located inside a loop formed by the band.
11. A substrate transport arm as in claim 10 where the four bar linkage comprises a quadrilateral linkage have four rotating joints all located at the second link.
12. A substrate transport arm as in claim 11 where the quadrilateral linkage comprises a convex quadrilateral linkage.
13. A substrate transport arm as in claim 10 where the third link comprises an end effector, and where the wrist member rotatably connects the end effector to the second link.
14. A substrate transport arm as in claim 10 where the shaft is fixedly connected to the first link, and where the shaft extends at least partially into the second link at the joint between the first and second links.
15. An apparatus comprising:
a robot arm comprising a first link, a second link rotatably connected to the first link, and an end effector rotatably connected to the second link, where the first link, the second link and the end effector are connected in series, where the end effector is connected to the second link by a wrist member rotatably attached to the second link;
a four-bar linkage connected to the second link, where the four-bar linkage comprises a carrier rotatably mounted to the second link, the wrist member rotatably mounted to the second link, and two bars connecting the carrier to the wrist member, where the two bars have first ends rotatably connected to the carrier and second ends rotatably connected to the wrist member, and where the carrier comprises a rotatable carrier pulley rotatably mounted to the second link; and
a driver at a joint of the second link to the first link, where the driver is connected to the rotatable carrier pulley to rotate the rotatable carrier pulley on the second link based upon the second link rotating relative to the first link, where the driver comprises a shaft fixedly connected to the first link, a drive pulley on the shaft, and a band connecting the drive pulley to rotatable carrier pulley, where the shaft has the drive pulley fixed thereto such that rotation of the first link relative to the second link effects rotation of the second link relative to the drive pulley, where the drive pulley is located inside a loop formed by the band,
where the driver and the four-bar linkage are configured to maintain radial orientation of the end effector to a limited single orientation relative to the first and second links regardless of a rotational angle of the second link relative to the first link.