For tasks that need to be accomplished in unconstrained environments, as in the case of Urban Search and Rescue (USAR), human-robot collaboration is considered as an indispensable component. Collaboration is based on accurate models of robot and human perception consistent with one another, so that exchange of information critical to the accomplishment of a task is performed efficiently and in a simplified fashion to minimize the interaction overhead. In this paper, we highlight the features of a human-robot team, i.e. how robot perception may be combined with human perception based on a task-driven direction for USAR. We elaborate on the design of the components of a mixed-initiative system wherein a task assigned to the robot is planned and executed jointly with the human operator as a result of their interaction. Our description is solidified by demonstrating the application of mixed-initiative planning in a number of examples related to the morphological adaptation of the rescue robot.