Challenges of Using Gestures in Multimodal HMI for Unmanned Mission Planning

As the use of autonomous systems continues to proliferate, their user base has transitioned from one primarily comprised of pilots and engineers with knowledge of the low level systems and algorithms to non-expert UAV users like scientists. This shift has highlighted the need to develop more intuitive and easy-to-use interfaces such that the strengths of the autonomous system can still be utilized without requiring any prior knowledge about the complexities of running such a system. Gesture-based natural language interfaces have emerged as a promising new alternative input modality. While on their own gesture-based interfaces can build general descriptions of desired inputs (e.g., flight path shapes), it is difficult to define more specific information (e.g., lengths, radii, height) while simultaneously preserving the intuitiveness of the interface. In order to assuage this issue, multimodal interfaces that integrate both gesture and speech can be used. These interfaces are intended to model typical human-human communication patterns which supplement gestures with speech. However, challenges arise when integrating gestures into a multimodal HMI architecture such as user perception of their ability vs. actual performance, system feedback, synchronization between input modalities, and the bounds on gesture execution requirements. We discuss these challenges, their possible causes and provide suggestions for mitigating these issues in the design of future multimodal interfaces. Although this paper discusses these challenges in the context of unmanned aerial vehicle mission planning, similar issues and solutions can be extended to unmanned ground and underwater missions.