Hired as a senior software designer and, later, as a consultant,
Mr. Potter was group leader for a small software team
producing code for passenger door control systems.
A variety of systems were produced, based on operators that were driven
by pneumatic, hydraulic, or electric-motor powered actuators.
A variety of methods for obstruction detection logic were implemented.
In particular, for the SkyTrain passenger door control systems in Vancouver,
and the Intelligent Door System (IDS), which beat all expectations for obstruction performance.

Skytrain (Vancouver)	IDS Intelligent Door System (prototype for London Underground) (Video: 8+ mins)
An "extra", picked up at Vapor:-