User manual

Barrett Technology, Inc.

BA4-310 System User Manual Version 1.1

5.6 Elbow Joint (J4, M3)

Although the M3 cable circuits are conceptually the same as for motor axes 0-2, the

pulley/pinions and second-stage pulley for motor axis 4 look very different. For Joint 4, both

pulley/pinions are on the same shaft and their pulley surfaces actually merge such that 1

-stage

cables can wrap across the seam between them. The motor pinion is also separated from the

rest of the transmission by the length of the inner arm link. Due to tight clearances in the elbow

between the 2

-stage pulley and pinion, temporary removal of the optional BarrettWrist will

facilitate re-cabling.

Before proceeding with the axis four cabling instructions, some directional references must be

defined.

If the user faces the

left

side of the elbow, the outer arm link will fold flat against the inner link

when the elbow joint (J4) is rotated fully clockwise. If the user faces the

right

side of the

elbow, the elbow output will rest against its rubber stop when the joint is rotated fully

clockwise. The right and left sides of the elbow match the users left and right sides when the

user is facing the

front

of the elbow. The

back

of the elbow is simply opposite the front.

The term

inboard

shall mean “toward the elbow’s plane of symmetry,” and the term

outboard

shall mean “away from the elbow’s plan of symmetry.” Rotational directions (clockwise &

counter-clockwise) are described relative to the side of the elbow that the user is facing.