This paper describes a contactless speed sensor based on the microwave radar technology for the use of a high precision train control system. Conventionally, a train speed is detected using a speed generator. Since the speed generator measures the speed based on the wheel diameter and the number of wheel rotations, measurement errors occur due to the variation in wheel radius, slipping of wheels during accelerating, and sliding of wheels during braking. To solve these problems, the use of the microwave radar was focused on that can detect the relative speed of the train and ground directly by contactless measurement. The speed measured by the microwave radar is not affected in principle by slipping, sliding and abrasion of the wheel. Here the development of the contactless speed sensor and the evaluation of the performance of it are reported. Tests were performed in the real track under a condition without wheel slipping and sliding. The measured speed and running distance of the proposed sensor were compared with those obtained with the traditional sensor. Under such conditions, the proposed sensor output faithfully agreed with that of the traditional sensor. The repeat measurement error (±5σ, σ: Standard deviation) of the proposed sensor was less than 1% in 10 trials, that was as same as that of the traditional sensor. The experimental results have shown that the proposed sensor is indeed feasible for the use of the train position detection.
