Mutually coupled multiple inductive loop system suitable for heterogeneous traffic

A magnetically coupled multiple inductive loop detector system is presented in this study. Automated detection, classification and measurement of speed of vehicles are challenging tasks, in a no-lane disciplined and heterogeneous traffic. This study proposes an inductive loop sensor wherein multiple numbers of small loops are placed within a large outer loop, for measurement of traffic parameters under such traffic. In the new system the outer loop alone is connected to the measurement unit and all the small loops are coupled inductively to the outer loop. This scheme is simple and effective and can be employed to convert an existing single loop system to a multiple loop system, suitable for heterogeneous traffic. The measurement is based on a synchronous detection method. A special excitation that ensures parallel resonance of the inductive system is employed, which keeps the power consumption minimum. The new system correctly sensed the vehicles, categorised and counted them in undisciplined traffic. The proposed system has been also extended to detect the direction of travel and speed of the vehicles. Results from the prototype developed were found to be accurate proving its practicality in real time traffic monitoring and intelligent transportation system (ITS) applications under a heterogeneous scenario.