Improvement of RTLS Performance Using Recursive RF Active Echo Algorithm

Abstract

When it comes to indoor Real-Time Location Systems (RTLS) for an Automatic Guided Vehicle (AGV), the most important factor is to minimize the location estimation error. In industrial sites, centimetre-level accuracy is required for the AGV. Since the duration for measuring the position of an AGV is slower than the speed of arriving RF signals, the margin of error inevitably becomes larger than in systems that use low-speed media such as ultrasonic waves. To minimize such errors, a short-range location estimation Recursive RF Active Echo (RRFAE) algorithm is presented. Increasing the time ratio by repeatedly and interactively reflecting the signal can reduce measurement error. That is, there is an effect of expanding the measurement distance by the number of iterations. We propose and implement a precise positioning algorithm in an indoor environment where many reflections exist. The error analysis of the RRFAE algorithm after hardware correction shows that the level of the RRFAE's errors is only one tenth that of an RTLS system that uses other RF signals.