User manual

Barrett Technology, Inc.
BA4-310 System User Manual Version 1.1
6
1.2 BarrettWrist (BW3-210)
Similar to the BarrettArm, the BarrettWrist utilizes various metal alloys and plastics to achieve
its structural strength and lightweight. The servomotors for axes 4 & 5 (this discussion
assumes the wrist is connected to the 4-DOF BarrettArm) are located at the base of the wrist to
minimize their inertial effects on the host robot arm. The final roll joint in the BarrettWrist,
motor axis 6, is the only geared axis. Since cable circuits generally have a size versus torque
relationship that limits the minimum characteristic size of a transmission, gears were an
appealing trade-off (in this axis only) for the significant decrease in distance between the grasp-
center of an attached end-effector and the wrist-center.
The 1
st
and 2
nd
stage transmission cables for motor axes 4 & 5 are accessed by sliding the cover
clamp off the Transmission Cover and pulling the cover around the wrist. To access the final
stage cables, the user is required to remove 4 socket cap screws from each black nylon guard at
the top of the wrist and then to pull off each guard. Since the final cable stages for motor axes
4 & 5 require infrequent maintenance, removal of these guards will rarely be necessary.
The threaded base of the BarrettWrist is fully compatible with the mechanical and electrical
quick-connect features on the BarrettArm.
Figure 2 - BarrettWrist BW3-210