Comparison of Uni- and Multimodal Interfaces for Spatial Human-Robot Interaction

Multimodal user interfaces hold the promise to enable natural and intuitive means of human-machine interaction. But is the effort of using many sensors rewarded by the users - or is a single modality sufficient? For an industrial use case of a weld seam inspection workstation we study three independent interfaces (augmented spatial button interaction on (1) a workpiece or (2) a worktable and through (3) speech commands) and their combination (4). While users preferred the interaction on the augmented worktable when comparing single modalities, they used all three in multimodal user interface. From the isolated test of an input modality it is not possible to infer its use in a complex system. Therefore, the effort implementing and using multiple input modalities is reasonable.