Stability Of Closed-loop Error System Research Articles

Passivity-based adaptive tracking control of spacecraft line-of-sight relative motion with thrust saturation

This paper considers the control problem of spacecraft line-of-sight (LOS) relative motion with thrust saturation in the presence of unmodeled dynamics, external disturbance and unknown mass property. By using skew-symmetric property, reference trajectory generator and anti-windup technique, a novel passivity-based adaptive sliding mode control (SMC) scheme is proposed without prior knowledge of uncertainty/disturbance bound. Within the Lyapunov framework, the establishment of a real sliding mode (which induces the practical stability of closed-loop error system) is validated. The main contributions are that a new control gain adaptive algorithm is adopted to attenuate the overestimation of switching gain and a differentiable projection-based parameter adaptive algorithm is proposed to force the mass approximator to remain in a desired domain, then the adaptive control law is modified by the reference trajectory generator and anti-windup technique to compensate for the effect of thrust saturation. Finally, simulations are conducted to show the fine performance of proposed control scheme.

Flatness-based Feedforward and Feedback Control for Fuel Rail System of Gasoline Direct Injection Engine

For gasoline direct injection (GDI) engines, obtaining desired rail pressure has become a key prerequisite of fuel injection quantity precise control. Since improved control performance and robustness will translate into better combustion stability, fuel economy and emissions. This paper develops a feedforward-feedback controller based on a nonlinear model of fuel rail system, where nominal feedforward control is derived by differential flatness and fuel rail pressure is selected as flat output. In feedback part, to simplify the design, the system is linearized on equilibrium point using Taylor series expansion, and Lyapunov method is used to ensure stability of closed-loop error system. Finally, the proposed controller is verified by fuel rail system simulation model established in AMESim software package, the simulation results in different pressure references demonstrate the effectiveness of the control system.