System and method for detecting wheel slip and skid in a locomotive
A system and a method for determining a true acceleration and velocity of a locomotive and for controlling wheel slip and wheel skid of the locomotive is disclosed. The system, using accelerometers, can control the velocity of the wheels of the locomotive based on the comparison between a true locomotive velocity signal and a wheel velocity signal such that an actual tangential speed of the wheels is regulated to correspond to the true locomotive longitudinal velocity plus an allowance velocity for creepage. The accelerometer can also be used at the same time for impact detection purposes. Furthermore, if a set of accelerometers are used, the locomotive can also play a diagnostic role for track quality reporting in rail yards. The control of wheel slip and wheel is particularly useful in DC locomotive applications with individual axle control.
1. A system for determining a true acceleration and velocity of a locomotive and for controlling wheel slip and wheel skid of the locomotive comprising:
longitudinal accelerometer means producing a signal a 1 representative of a true locomotive longitudinal acceleration;
processing means for processing the signal a 1 to produce a signal v 1 representative of a true locomotive velocity;
wheel velocity measurement means for producing a wheel velocity signal w 1 representative of a velocity of at least one wheel of the locomotive;
comparing means comparing the true locomotive velocity signal v 1 to the wheel velocity signal w 1 ; and
a controller for controlling the velocity of the at least one wheel of the locomotive based on the comparison between the true locomotive velocity signal v 1 and the wheel velocity signal w 1 such that an actual tangential speed of the at least one wheel is regulated to correspond to the true locomotive longitudinal velocity plus an allowance velocity for creepage.
2. The system according to claim 1 , further comprising normal accelerometer means producing a signal a 2 representative of a true locomotive acceleration in a direction normal to the longitudinal direction and wherein the processing means further processes the signal a 2 in conjunction with the signal a 1 in order to derive a grade angle and the signal v 1 representative of the true locomotive velocity taking into account the grade angle.
3. The system according to claim 1 , wherein the locomotive is a DC locomotive with individual axle control.
4. The system according to claim 1 , wherein the longitudinal accelerometer means further produces impact signals a 3 representative of impact forces exerted on the locomotive.
5. The system according to claim 1 , wherein the longitudinal accelerometer means further produces vibration signals a 4 representative of vibrations affecting the locomotive.
6. The system according to claim 1 , further comprising at least one offset accelerometer means located at an offset location with respect to the longitudinal accelerometer means, the offset accelerometer means producing a signal a 5 representative of an acceleration at the offset location.
7. The system according to claim 6 , wherein the longitudinal accelerometer means is positioned on a front truck of the locomotive and the at least one offset accelerometer means is positioned on a rear truck of the locomotive.
8. The system according to claim 7 , further comprising a GPS system for measuring the location of the locomotive.
9. The system according to claim 2 , wherein the longitudinal accelerometer means further produces impact signals a 3 representative of impact forces exerted on the locomotive and produces vibration signals a 4 representative of vibrations affecting the locomotive, the system further comprising at least one offset accelerometer means located at an offset location with respect to the longitudinal accelerometer means, the offset accelerometer means producing a signal a 5 representative of an acceleration at the offset location, the longitudinal accelerometer means being positioned on a front truck of the locomotive and the at least one offset accelerometer means is positioned on a rear truck of the locomotive, and the system further comprising a GPS system for measuring the location of the locomotive.
10. The system according to claim 1 , wherein the wheel velocity measurement means measures at least one of a wheel axle rotation per minute, a traction motor rotation per minute and traction motor current.