NASA and Xerox cooperate to develop voice info access for space station

“Clarissa” uses Nuance network-based speech recognition

Scientists from NASA Ames Research Center in California’s Silicon Valley and Xerox Corporation demonstrated “Clarissa,” a voice-operated computer system on June 26 at the Association for Computational Linguists’ 25^th annual meeting at the University of Michigan, Ann Arbor. Clarissa was designed to be an interactive user’s manual for astronauts, or, as the developers term it, a “virtual crew assistant.” Beth Ann Hockey, project lead on the team that developed Clarissa at NASA Ames, said that Clarissa enables astronauts “to be more efficient with their hands and eyes and to give full attention to the task while they navigate through the procedure using spoken commands.” The application uses network-based speech recognition from Nuance (SRU, April 2005, p. 13).

Astronauts now perform about 12,000 complex procedures to maintain life-support systems, inspect space suits, conduct science experiments, perform medical exams, and other routine tasks. Clarissa responds to astronauts’ voice commands, reading procedure steps out loud as they work, helping keep track of which steps have been completed, and supporting flexible voice-activated alarms and timers. Clarissa currently supports about 75 individual commands, which can be accessed using a vocabulary of some 260 words. “Some commands are rather simple, but others are quite complex,” Hockey said. “A lot of the time, you’re just saying ‘next’ or ‘go to step eight’. But you also might need to say something like ‘cancel the alarm at 10:25’ or ‘set challenge verify mode on steps three through fourteen.’”

Because the system is required to always be ready to accept a voice command, the original version tried to process all spoken words, including conversations between crew members. As a result, Clarissa had difficulty discerning between conversations and commands given to the system. NASA didn’t want the system to require an activation command, such as the word “computer” used in Star Trek.

In 2004, Clarissa lead implementer Manny Rayner of NASA Ames contacted Xerox researcher Jean-Michel Renders of Xerox Research Centre Europe in Grenoble, France, about a possible collaboration. They hoped that Xerox’s experience in machine learning, linguistics, and text categorization would increase the system’s accuracy on the “open microphone” task. The Xerox methodology now allows Clarissa to more accurately analyze each utterance. It can recognize words, sentences, and word context and can act on a variety of commands phrased in different ways. The system now looks at all the individual words within the sentence, takes into account the system’s confidence that it has correctly recognized each individual word, and uses a sophisticated machine-learning algorithm to weigh the various pieces of positive and negative information. According to Renders, the improvements have cut the error rate of the system by more than half.