Autonomous robots are currently engaged in emergency informatics and participate in operations such as search and rescue. Real-time data collection is a key requirement while there are constraints on the space, height and weight of the hardware on-board with such robots. In this paper, we investigate the amount and sophistication of sensing and processing hardware needed by a mobile robot for performing high-level tasks in real time. In particular, we consider two tasks, namely azimuth calculation and dynamic obstacle tracing and show that one ultrasonic sensor along with a coordinate rotation digital computer processor are adequate for azimuth calculation while one more ultrasonic sensor is required for dynamic obstacle tracing. For dynamic obstacle tracing, we also study a related problem of optimal placement of a pair of ultrasonic sensors. Experiments with a field programmable gate array-based robot equipped with ultrasonic sensors are presented to support the theory. © 2016 IEEE.