that the tracks do not lose traction. This is not a concern on short staircases as it is on

longer ones.

 It should be noted that the portion of the stair motion algorithm, as seen in Figure 3-4,

is the same for both the ascend and the descend behavior commands. Also independent

of the direction of travel upon the stairs is the protocol arbiter. Protocol 1 is designated

for control of the Andros on a set of stairs less than the critical length in both the ascend

and descend commands, protocol 2 corresponds to control of the Andros on a set of stairs

longer than the critical length in both the ascend and descend commands.

 Once the stair protocol has been carried out, the controller reverts back to its ready

state and awaits further commands from the System Commander.

3.2.4 Ascend Protocol 1

 This stair motion protocol deals with the situation in which the total length of the

staircase is less than the critical length. First, the front auxiliary tracks of the Andros are

aligned with the angle of the stairs, P. (Figure 3-7a) Then, the Andros is simply started

up the staircase. The protocol concludes as the Andros passes the last step of the

staircase and is safely situated on the top landing, as seen in Figure 3-7c.

3.2.5 Ascend Protocol 2

 The second ascend stair motion protocol deals with the situation where the total

length of the staircase is longer than the critical length. In this situation, the full range of

control steps are necessary to ensure that the Andros makes it safely to the top of the

staircase. The first stage of the process is to align the front auxiliary tracks of the Andros

with the angle of the stairs, 0, and the rear auxiliary tracks parallel to the ground. (Figure

3-7a) This stage occurs while the Andros is preparing to climb the staircase, therefore