Distance sensing for mini-robots: RSSI vs. TDOA

This paper reports a compact, robust distance-only sensor for networked small robotic platforms. Two methods of sensing distance (neglecting heading) between robots are discussed: Received Signal Strength Indicator (RSSI) and Time Difference of Arrival (TDOA). Both implementations make use of a commercially available wireless sensor network board for communication and processing. Although RSSI requires no additional hardware, TDOA requires several additional components including a sound source and microphone. While experimental results indicate that both methods can provide distance sensing within a local neighborhood, TDOA sensing was found to be more robust and accurate, providing 1 cm distance resolution over a range of 80 cm versus 2.4 cm for RSSI. These sensors have been integrated onto mini-robotic platforms by incorporating a heading estimator and controller.