Mass Estimation and Axle Load Distribution Algorithm for EBS of Large Bus 2013-01-0417
The paper describes an algorithm, which estimates the mass of large buses and axle load distribution using pedal position, wheel speed and the wheel cylinder pressure sensors. This algorithm is allowed to achieve the purpose without additional sensors by using the rotational speed sensors from ABS system and air pressure sensors in brake cylinders form ESP system.
The axle load distribution algorithm mainly consists of three steps. Firstly, deceleration of the bus is estimated and then the mass of the bus is estimated. After that, the position of the mass centre is estimated. Taking account of the tire nonlinear characteristics under longitudinal forces and vertical forces, mass estimation, deceleration and the position of the mass centre of buses is corrected by the coefficient, which is determined by the wheel cylinder pressure, the wheel speed and mass estimation.
When the deceleration, mass of the large bus and the mass center of the whole bus are completely estimated, load of each axle can be obtained through the formula, and also the optimal braking force of each axle for Electronically Controlled Brake System (EBS) can be determined.
The comparison between the value of estimation and the value from the Trucksim indicates that: the estimation algorithm is able to achieve accurate value of the mass and axle load of the bus and lays a ground for the development of EBS.