Clutches are widely used in various vehicle powertrains. The engagement process of a friction clutch has three phases, i.e., open, slipping, and sticking. Transitions between different phases introduce a discontinuity to the powertrain dynamics, which has been neglected in previous research. A model referenced adaptive controller (MRAC), based on Popov hyper-stability criterion, is designed to compensate the discontinuity. MRAC adjusts the frictional torque along with the errors of the state variables compared with those of a referenced model. The designed MRAC is applied to a clutch in a bus. Simulation and experimental results under fast and slow startup cases show that MRAC can simultaneously reduce vehicle jerk and frictional dissipation when compared with the conventional controller.
This paper presents an aerostat developed in the shape of an ellipsoid, which is a cross between a ball and a water droplet. This aerostat is equipped with four vectored thrusters. Its coefficient of forward drag is smaller than that of the spherical aerostat, and its lift efficiency is higher than that of the conventional airship. To allocate control among the multi-vectored thrusters, a control system based on pseudo-inverse dynamics is designed. A reconfiguration strategy is also proposed to reallocate actuators in case of control actuator failure. Three diagonal weight matrices are combined to represent all possible failure situations occurred on vectored thruster, they make the reconfigurable controller more general. Based on simulation results under different fault situations, the reconfigurable control system performs more effectively than a normal control system in cases of actuator failure, even when more than one actuator fails. Reconfigurable ability of controller also validated in real flight experiment.
A fault-tolerant function is critical for ensuring sufficient reliability and performance availability of control units in hybrid electric vehicles. For the purpose of providing a fault-tolerant system, a systematic integral power management strategy for a complex hybrid electric vehicle is presented at a system level. Once a subsystem component failure occurred, the hybrid vehicle system controller can take effective actions to achieve an acceptable performance. For instance, when the engine or battery fails to work, a limp-home operation is expected. Operational characteristics under normal modes and failure modes are discussed and a combined rule-based control strategy is developed to manage the power flow. Vehicle simulation integrated with a control algorithm is constructed and carried out in MATLAB/Simulink/Stateflow. Performances under normal and abnormal conditions are evaluated respectively.
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