This position paper makes a case for the need to predict pedestrian position and schedule communication acts in mobile navigation systems. In our work, carried out in the context of a voice guided city navigation system, we have found that improperly timed route instructions are a major cause of failure in guiding pedestrians in unknown environments. Furthermore, the need to communicate other information while guiding users on routes, as well as complications caused by network latencies, occurs often enough to require that we be able synchronize communication acts with user position as they follow a route. This has led us to focus our efforts on scheduling utterances to maximize route following success.
In this position paper we motivate this problem and present our initial approach and findings which should be of interest to others engaged in similar efforts in both the Geography and HCI communities.