Sturdy-Door

You may also be looking for the similarly-titled episode.

The Sturdy-Door Wall Traversal Unit is a type of SOOTH-derived door developed by researchers at the Theoretical Structures Lab in Halcyon Tower.

Its creation is discussed at length in "Doors". The Sturdy-Door was designed to open as quickly and efficiently as possible, with the minimum number of false positives possible. While early versions used a sensor array, this led to the doors very often opening for residents who did not intend to open the door. Researchers attempted a version where doors responded to a signal such as a resident approaching with a hand raised, but found it impractical because residents carrying large objects would not be able to signal the door. Next, a version which attempted to judge residents' facial expression to determine if they intended to open the door was tried, but the recognition engine misjudged the situation in 46 out of 71 attempts. At this point, it was shelved until the Applied Probabilistics Lab developed SOOTH. With the ability to quantify alternate possible realities, researchers had the doors check three seconds into the future in the realities where doors were not automatic to see if the door was open or not, and open the door based on the percentage of open doors. This system resulted in the Sturdy-Doors being correct about whether or not to open with perfect accuracy.

While Sturdy-Doors are capable of opening automatically, they can also be fitted with thought passwords, and this type of setup is used to secure residents' personal quarters.

Issues
During development, it was noted that SOOTH returned more alternate reality versions of the doors than the number of alternate realities surveyed. In spite of this, the doors were put into production. Some time later, an extra door appeared which did not lead to the destination visible through the door way. These extraneous doors appear from time to time, and can lead not only to other places on Typhon, but also to places in other realities. This is the core issue in the episode "Doors" and the focus of a series of alerts in "Dissonance".

Trivia

 * Despite being able to open automatically, Sturdy-Doors do have a handle of some kind. This is presumably related to the idea that some of them might be locked by thought passwords.
 * The Sturdy-Door is apparently a relatively recent invention, as it was still in development at the start of Season Five.