Estimation of Locomotive Adhesion Coefficients and Slip Ratios

Wheel slip control of locomotive traction systems is difficult because of the uncertainty in the non-linear wheel-surface behaviour, the unknown adhesion conditions and the difficulty in obtaining the slip ratio. Continuous controllers can perform better than traditional rule-based controllers if the uncertainty can be reduced using effective estimation. A novel linear state-observable estimator is presented that produces estimates of the slip ratios and adhesion coefficients of each locomotive wheelset. The estimator requires measurements of the locomotive velocity and acceleration. The estimator includes the estimation of the normal forces of each wheelset to increase the adhesion coefficient estimation accuracy.