This ongoing project aims at implementing spatial awareness in situated agents. The concept is being tested using Croquet as collaborative environment and interactive exhibition layout as field of application. Thereby the agents are used as invisible vehicles for the exhibits, essentially controlling their location and orientation.

Spatial awareness, the concept of realising your spatial situation relative to that of other entities and perhaps being able to infer how this relationship will change upon action can be seen as a step towards spatial reasoning. While this is a grand enough target in its own right, the need to represent and test functionalities called for a virtual-world problem as a case study. Exhibition layout was chosen as test case since it offers numerous spatial relationships which must be considered. First, there is the exhibit-to-exhibit relationship. Exhibits may not collide and the users view to another exhibit may not be obstructed. Second, one must consider the exhibit-to-user relationship. The exhibit must face the viewer while enabling sufficient distance or proximity to achieve the intended experience. Third, there is also a kind of exhibit-ensemble-to-user relationship which cannot simply be seen as an addition of the former two, but rather requires a second order awareness of relationships between other entities. Individual agents must sometimes agree to suboptimal positions for the benefit of the group.

A subsumption architecture forms the basis of the agent’s behaviour. These kinds of rule-based hierarchies mainly operate as mapping from sensory inputs to actions, thus by-passing the need for elaborate internal models.

The main inputs the agent can operate with are the relative positions of the other exhibits, user actions, agent communication, geometric site constraints, the overall layout concept as well as a popularity measure derived from user interaction. Thereby the user actions, the agent communication and the popularity measure are the only active elements and hence serve as triggers for the agent’s behaviour. The relative positions, the site constraints, the layout concept and the popularity measure account for the environments current situation and hence can be seen as the agent’s external memory. Once the agent’s behaviour is triggered all the above inputs are used to determine the appropriate reaction.

The agent’s lowest level behaviour is to check various lines of sight, depending on the intended layout. This can be with respect to a single vantage point or a vantage line. In order to keep computation low and responsiveness high bounding sphere algorithms are used for this step. Future versions should implement more finely grained algorithms. The second level is concerned with the exhibits orientation towards the viewer and the surrounding exhibits. The third level essentially implements the popularity measure as a ordering of the respective ensembles. The fourth level checks whether the intended layout concept is being realised successfully. Finally, the top layer ensures that the geometric constraints imposed by the site are met.

References 
Brooks, RA: 1986, A Robust Layered Control System for a Mobile Robot, IEEE Journal of Robotics and Automation 2(1): 14-23.
Gero, JS and Kannengiesser, U: 2004, The Situated Function-Behaviour-Structure Framework, Design Studies 25(4): 374-391.
