Menghua Zhang

Nonlinear coupling control method for underactuated three-dimensional overhead crane systems under initial input constraints:

In this paper, we present an enhanced coupling nonlinear control method for three-dimensional overhead crane systems under initial input constraints. The proposed control method can achieve superior control performance and strong robustness with respect to system parameter variations and external disturbances. Moreover, it guarantees ‘soft’ trolley start by introducing hyperbolic tangent functions into the controller. More precisely, we enhance the coupling behaviour between the trolley movement and the payload swing by fabricating two composite signals, based on which an energy-like storage function is established. Then, a nonlinear coupling control method under initial input constraints is derived directly. Lyapunov techniques and LaSalle’s invariance theorem are successfully adopted to find the asymptotic stability solution while satisfying the initial input constraints. Strict mathematical analysis of the control scheme with initial input constraints is provided as theoretical support for the superior performance of the controller. Simulation and experimental results are conducted to show the superior performance and strong robustness of the proposed control method.

Information fusion control with time delay for smooth pursuit eye movement

Smooth pursuit eye movement depends on prediction and learning, and is subject to time delays in the visual pathways. In this paper, an information fusion control method with time delay is presented, implementing smooth pursuit eye movement with prediction and learning as well as solving the problem of time delays in the visual pathways. By fusing the soft constraint information of the target trajectory of eyes and the ideal control strategy, and the hard constraint information of the eye system state equation and the output equation, optimal estimations of the co‐state sequence and the control variable are obtained. The proposed control method can track not only constant velocity, sinusoidal target motion, but also arbitrary moving targets. Moreover, the absolute value of the retinal slip reaches steady state after 0.1 sec. Information fusion control method elegantly describes in a function manner how the brain may deal with arbitrary target velocities, how it implements the smooth pursuit eye movement with prediction, learning, and time delays. These two principles allowed us to accurately describe visually guided, predictive and learning smooth pursuit dynamics observed in a wide variety of tasks within a single theoretical framework. The tracking control performance of the proposed information fusion control with time delays is verified by numerical simulation results.

A novel energy-coupling-based control method for double-pendulum overhead cranes with initial control force constraint

A novel energy-coupling-based control method for under-actuated double-pendulum overhead cranes with initial control force constraint is proposed in this article. The significant feature of the designed controller is its superior control performance as well as its strong robustness with respect to parameter variations and external disturbances. By incorporating a smooth hyperbolic tangent function into the control law, the proposed controller guarantees soft start of the trolley. Moreover, to improve the transient performance of the crane system, coupling behavior among the trolley movement, the hook swing, and the payload swing is enhanced by introducing a generalized payload horizontal-displacement signal. Lyapunov techniques and LaSalle’s invariance theorem are utilized to prove the stability of the designed closed-loop system. Simulation results demonstrate that the new energy-coupling control method achieves superior control performance and strong robustness over different payload masses, cable lengths, desired positions, and external disturbances with reduced initial control force.

Modeling and energy-based fuzzy controlling for underactuated overhead cranes with load transferring, lowering, and persistent external disturbances

In practice, vertical load motion is always involved in overhead cranes. In this case, the cable length turns from a constant to a variable, which may induce large amplitude load swing and make it more challenging to develop an appropriate controller. Most existing control methods for varying-cable-length cranes require either linearization or approximation to the original nonlinear dynamics; moreover, the case of external load disturbances is not fully considered. Inspired by these facts, we build the model and suggest an energy-based fuzzy control method for underactuated overhead cranes with load transferring, lowering, and persistent external disturbances. To estimate the persistent external disturbances, we construct a fuzzy disturbance observer. And a strict mathematical analysis of the control method without linearization approximation is presented, providing theoretical support for the superior performance of the proposed controller. Lyapunov techniques and LaSalle’s invariance theorem are used to demonstrate the stability of the closed-loop overhead crane system. Numerical simulation results are included to examine the effectiveness and robustness of the proposed method.