A simple method for dynamically measuring the diameters of train wheels using a one-dimensional laser displacement transducer

Abstract A simple method for dynamically measuring the diameters of train wheels that uses a relative measurement system is proposed. Only a laser displacement transducer and eddy current sensors are used to dynamically measure the wheel diameter when a train passes through the measurement device, and a simple equation for computing the diameter is given. The main factors influencing the measurement uncertainty were analyzed and simulated, and the effect of vibration on the diameter measurement was also analyzed using a simulation based on the finite element method. The measurement error of a laser displacement transducer, the position error and vibration are the primary factors that influence the accuracy of the diameter measurement, and of these factors, the influence of vibration can be reduced by comparative measurement. To further decrease the influence of wheel position error on the accuracy of the diameter measurement, two eddy current sensors were used instead of only one eddy current sensor, and the simulation results indicated that the influence of wheel position error on the accuracy of the diameter measurement can be greatly reduced. The theoretical analysis indicated that the measurement device has a measurement uncertainty of ±0.37 mm, which agrees with the site experimental results, and the measurement system can satisfy the requirements of dynamically measuring the train diameters in situ.