Modelling, Analysis and Experimental Verification of Pneumatic Brake System

As the technology develops, the development in vehicle safety becomes an area,
which takes the attraction of the researchers who are working in automotive industry.
Although systems like air bag system, lane departure warning system (LDWS) and
tire pressure monitoring system (TPMS) improve the safety of the vehicle, main
studies, in which advanced technology is used mostly focus on the brake system
including anti-lock braking system (ABS), traction control system (TCS), electronic
stability control (ESC), advanced emergency braking system (AEBS), adaptive
cruise control (ACC). Thus, detailed studies should be conducted on brake and brake
system mechanism to understand, which parameters affect the braking performance
of the vehicle.
Primary aim of this study is to obtain a detailed dynamic model of pneumatic brake
system that will be verified with vehicle tests and be used for response time
prediction on vehicle level. Secondary aim is to develop a model based design tool,
which will be able to improve the response time and also the brake performance
during the design stage of vehicles.
In this study, a general mathematical model is proposed to determine the dynamic
characteristics of pneumatic brake system. For this purpose, first of all the details of
pneumatic and mechanical subsystems of the air brake system are investigated. After
that; in order to be able to execute the simulations, mathematical equations of the
mechanical and pneumatic subsystems are derived and these equations are adapted to
the Simulink model.
When constructing the Simulink model, some system parameters are obtained from
the basic models in the literature and some are taken from the technical datasheets of
the brake system components. Since a more complicated pneumatic brake system is
aimed to be modeled, much more system parameters are required to be estimated. To
identify those unknown parameters, response time tests were performed on a 4x4
xxiv
heavy-duty vehicle equipped with wedge drum brakes. The experimental results of
those tests are used to tune the system model for the unknown parameters.
For verification, simulations, which include proposed pneumatic brake system
model, are performed on a different vehicle and these numerical results are verified
with the vehicle tests. Here a prototype 4x4 heavy-duty vehicle equipped with disc
brakes is used for the experimental study.