Abstract: Aircraft apron ground operation could be divided into the low-speed (less than 6 knots, about 11.11 km/h), middle-speed (6－14 knots), and high-speed (large than 14 knots, about 25.93 km/h) three cases. Comparing to the traditional low-speed aircraft towing operation, the traction velocity in the new-generation towbarless aircraft taxiing mode could reach to 40 km/h, in this case the wet road has a significant influence on the braking performance of a towbarless aircraft towing taxiing system (TLATS). The "pseudo" flow dynamic pressure bearing effect is used to be equivalent to the interaction among the tire, water film and road, and an advanced Lugre tire hydroplaning dynamic model is developed by combining the arbitrary pressure distribution function. The wet road tire adhesion experiments are conducted for a specific tire of the AM210 towbarless towing vehicle (TLTV), and the Lugre tire hydrodynamic model parameters are identified based on the experimental results. A co-simulation dynamic model of the Lugre tire hydrodynamic model in Matlab/Simulink and the TLATS in Adams/View is established. By employing the same fuzzy PID optimal slip rate control method and considering the rough road vibration excitation, the braking performances of the TLATS under wet road conditions are compared with those under dry road condition. It shows that the vertical tire dynamic load under wet road condition is smaller than that under dry road condition, and the tire grip performance decreases when the water film thickness increases. The braking distances for the A class and C class roads with 1mm water film increased 30.9% and 31.3%, respectively, than that under the dry rough roads with an initial braking speed of 40 km/h. The braking distance of 1mm water film surface increased by 2.7% and 2.5% respectively compared with that of 0.5mm water film surface under corresponding working conditions. The results could provide an theoretical basis for predicting a safe braking distance on wet road in the aircraft towing operation accurately.

Key words: TLATS, TLTV, wet road, tire dynamic model, braking dynamics