Track gauge dynamic measurement based on 2d laser displacement sensor
Track irregularities can cause deterioation of riding comfort and derailment. Track gauge variation is one of the basic track irregularities. Track Recording Car is an automated track inspection vehicle on a rail transport system used to test several geometric parameters of the track. Track geomeotry parameters generally measured include position, speed, gauge, alignment, crosslevel, curvature and so on. This paper presents a novel technique for the measurement of track gauge variation, a new measurement system was introduced and been in assembled on a new type underground track recording car.
Track-recording techniques used on British Rail
Accurate and consistent data on railway-track quality is required from which track-maintenance action can be scheduled. In recent years two recording vehicles have been designed by British Rail: a high-speed track-recording coach (HSTRC) to provide maintenance data for the Civil Engineering Department, and a self-propelled diesel multiple unit used by the Research and Development Division for investigative work. For HSTRC a measuring system was needed which would be reliable under intensive running conditions, and which could be fitted to a standard coach with the minimum of mechanical modification. Conventional multiwheel or multiprobe systems were rejected because of the considerable mechanical complexity of the undergear, in favour of a single-point system using inertial techniques and measuring in the vertical plane through the running wheels and in the horizontal plane through noncontacting optical-scanning equipment. The inertial measuring system uses transducers, including accelerometers, rate gyroscopes and displacement transducers which provide inputs to special-purpose electronic processing networks which provide the required profiles. Onboard computer systems analyse the data to form track-quality estimates which are listed and recorded on magnetic tape for transfer to a central mainframe data bank. Operation of the track-recording coach is controlled by an automatic route-definition procedure using data stored on a central track-route data bank.
Variable-bandwidth filters using switching
It is shown that, if a switching technique is used to scale the bandwidth of a lowpass filter, the resultant circuit has some of the characteristics of an N-path filter. The consequence of this is that the signal frequency must be bandlimited to avoid spurious responses at the switching frequency and its harmonics.