TeDUB was a European Union-funded project running from 2001 to 2005. It was intended to deliver a way for blind people to access arbitrary technical diagrams - engineering, architectural and so on. It failed to deliver anything on this front.
However, it did produce, through the University of Manchester, the Accessible UML tool for helping blind people read software engineering UML diagrams. This enabled users to open UML diagrams in the XMI XML format, a format for UML diagram files that can be exported by tools like Rational Rose and Poseidon UML. Users could then explore the diagram contents using the keyboard or a joystick. You are very welcome to try out the program and use the source code.
For anyone interested in pursuing this: my opinion, with hindsight, is that the best approach would be simply to convert a UML diagram (from an XMI file) into an HTML document with lots of internal linking and plain text. This would be simpler and fit with screenreader user's standard ability to read web pages. You should look at the XSL files in config to see how this might be accomplished.