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C H A P T E R 3
State Estimation of
Cyber-Physical Vehicle
Systems
As we have mentioned, cyber physical systems, which are distributed, networked systems that
fuse computational processes with the physical world exhibiting a multidisciplinary nature, have
recently become a research focus [40–43]. As a typical application of CPS in green transporta-
tion, electric vehicles have been widely studied with different topics by researchers and engineers
from academia, industry and governmental organizations [44–50]. In an electric vehicle (EV),
the cyber world of control and communication, the physical plant of electric powertrain, the
human driver, and the driving environment, are tightly coupled and dynamically interacted, de-
termining the overall system’s performance jointly [51]. ese complex subsystems with multi-
disciplinary interactions, strong uncertainties, and hard nonlinearities make the estimation, con-
trol, and optimization of electric vehicles very difficult [52]. us, there are still quite a number
of fundamental issues and critical challenges varying in their importance from convenience to
safety of EV remained open [53–56].
Among all those concerns in EV CPS, a key one is safety. Safety critical systems are
those ones whose failure or malfunction may result in serious injury or severe damage to people,
equipment, or environment [57]. As one of the most important safety critical systems in EV, the
correct functioning of braking system is essential to the safe operation of the vehicle [58]. ere
are a variety of safety standards, control algorithms, and developed devices helping guarantee
braking safety for current EVs. However, with increasing degrees of electrification, control au-
thority and autonomy of CPVS, safety critical functions of braking system are also required to
evolve to keep pace [59].
In the braking system of a passenger car, the braking torque is generated by the hydraulic
pressure applied in the brake cylinder. us, the accurate measurement of the brake pressure
through a pressure sensor is of great importance for various braking control functions and chassis
stability logics. However, failures of the brake pressure measurement, which may be caused by
software discrepancies or hardware problems, could result in vehicle’s critical safety issues. us,
high-precision estimation of brake pressure become a hot research area in CPVS design and
control. Moreover, in order to handle the trade-offs between performance and cost, sensor-less
observation is required. is makes the study of brake pressure estimation highly motivated.
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