**6. Discussion**

The proposed framework for the dual-modality AR system was implemented for deployment in a laboratory setting where humans and mobile robots are expected to coexist and operate in close proximity. The mobile platform was 'let loose' within the laboratory without any prior briefing to the other laboratory users. Third party human-robot interaction was observed, and a 'qualitative' feedback was solicited from the 'unsuspecting' human. Two scenarios were evaluated. The first scenario was without the laser writer augmentation, and the second with the laser writer function activated. In this second scenario, the robot projected its action and indicated its motion trajectory.

Invariably the response was positive, especially when the robot was stationary and the human was unsure of the response required of them. In instances when the robot's route was identi‐ fied, humans would find an alternative route in an attempt to avoid the robot. The human response of avoiding the robot's workspace enabled the robot the option of increasing its speed resulting in better operational performance.

As a natural extension of the unmanned deployment of mobile robots, the framework of providing notification of the robot's actions is recognised to be supportive to the application of autonomous transportation in an urban scenario. In such a scenario, vehicles are larger and environments shared with humans who are less familiar with robot interaction. The ability to improve on the passerby's awareness of the robot's actions could be achieved using the laser writer information system described in this chapter. When the vehicle is avoiding or stopping for the human, appropriate indications may be provided to the human by use of the laser notification system.
