The second step in the setup was to affix a plumb compass to the auxiliary track so

that an independent angle measurement of the position of the track could be made. A

plumb compass is comprised of a needle, weighted at the bottom, along with an

adjustable faceplate. By attaching the body of the plumb compass to a structure, the

relative angle of the structure with respect to ground may be found when the structure is

rotated. The Andros auxiliary tracks were rotated to their bottommost point and the

adjustable face of the plumb compass was then adjusted such that the compass needle

pointed to 0 degrees. In this configuration, the compass needle pointed to 150 degrees

when the auxiliary tracks were rotated to their topmost position, which corresponds to the

measurement convention utilized by the controller. Figure 4-4 illustrates the plumb

compass attached to the Andros' auxiliary track.

 To test the commands for the auxiliary track positioning system, the Operator Control

Unit (OCU) was used to send the experimental JAUS message, "Set Auxiliary

Actuators," to the Andros' JAUS controller, along with a commanded angular position of

the auxiliary track. The initial set of commanded angles were used to determine the

minimum allowable tolerance that could be used by the system without the system

becoming unstable. In this case, the system would be unstable if the controller

continually reversed the direction of the auxiliary track in an attempt to move the track to

the desired angle and be within the given tolerance. The minimum allowable tolerance

for the system was found to be +/- 1 degree. Following this, another set of "Set Auxiliary

Actuators" commands were sent to the system and the commanded angle, the angle

returned by the DWT sensor, and the angle read off of the plumb compass were recorded.