Notes on ELL arm movement

Components:

The ELL arm assembly is consisted of two parts:

Upper part: visible with in the ELL.

Lower part—lower bearing housing.

Movement of upper part:

Rotation: Forearm (fork) locked to the upper arm. Upper arm and forearm rotate together against the etcher.

Extension: Upper arm (arm housing) rotates around the shoulder relative to the etcher in one direction. Forearm rotates around the elbow relative to the upper arm in the opposite direction with double the speed as the upper arm rotation.

Description of motion during Rotation:

Object / Motion type (translational motion/rotational motion, etc) / Direction (up/down, towards indexer, away from indexer, CW, CCW, etc.) / Extent of motion (how much does it move from beginning to end)
Upper arm against shoulder / Rotation / CCW / 90°
Fore arm against elbow / No motion. Thus locked in to upper arm / NA / NA
Shaft against etcher / Rotation / CCW / 90°
Tube against etcher / Rotation / CCW / 90°

Description of motion during extension:

Object / Motion type (translational motion/rotational motion, etc) / Direction (up/down, towards indexer, away from indexer, CW, CCW, etc.) / Extent of motion (how much does it move from beginning to end)
Upper arm against shoulder / Rotation / CCW / 90°
Fore arm against elbow / Rotation / CW / 180°
Shaft against etcher / No motion / NA / NA
Tube against etcher / Rotation / CCW / 90°

Cause of extension: arm housing (upper arm) rotation against etcher, shoulder pulley fixed against etcher. This relative motion of arm housing against shoulder pulley causes the belt around the pulley to wrap around or open up. Points on the belt move away from the shoulder on the side of the belt that opens up and gets closer to the shoulder on the side of the belt that wraps around. This relative motion of the belt against the shoulder from the perspective of a person standing on the shoulder drags and rotates the elbow pulley at the other end of the belt. This in turn causes the folk (fore arm) to rotate. The combined motion of upper arm rotation and that of the forearm form a extension motion of the ELL arm.

Cause of rotation: arm housing (upper arm) and the shoulder pulley both move relative to the etcher at the same pace. No relative motion of the arm housing against the shoulder pulley. No motion of the belt against the arm housing. No rotation of the elbow. Forearm/fork locked to the upper arm. They rotate together against the etcher.

Position Sensing:

There are two rotation positions of the ELL arm: 0 degree position--Ready to rotate to chamber position and 90 degree position--Ready to rotate to load-point position. (see figure below). There are three extension positions: Arm not extended (folded) position. Arm extended to the chamber (CW extension) and arm extended to the load-point position (CCW extension).

Ext and Rot sensors and flag wheels:

From this extension position, the flag disc rotates CCW 90° to reach the not extended position (in ELL) and another CCW90° to reach the extended to ldpt position.

Non-interruption = T in screen display

Interruption = F in screen display

Rot and Ext sensors mounted on lower bearing housing (boat). Rot flag wheel mounted on etcher. Ext flag wheel mounted on the tube. They are not on the same plane.

Relative orientation of the sensors to the chamber:

When the ELL arm is at the rotated to the chamber position, the sensor positions are shown as below:

Non-interrupted = T, interrupted = F.

Notice when the arm is extended into the chamber or to the ldpt, 9p5=T, 9P9=F, 9P8=T. Thus the etcher does not depend on the combination of sensor states to sense its position. Instead, it depends on some sort of sequential logic to do so, such as perhaps the transition from F to T to mark the position.

Sensor Position / Connector type / Software Index
Arm retracted / 9P9 / 60
Arm extended to ldpt / 9P5 / 71
Arm extended to chamber / 9P8 / 72
Arm rotated to ldpt / 9P6 / 73
Arm rotated to chamber / 9P7 / 74

1