Global satisfactory control for nonlinear integrator processes with long delay

Integrator processes with long delay are difficult to control. Nonlinear characteristics of actuators make the control problem more challenging. A technique is proposed in this paper for global satisfactory control （GSC） of such processes with relay-type nonlinearity. An oscillatory control signal is injected into the nonlinear process; the amplitude and frequency of the oscillatory signal are designed to linearise the nonlinear process in the sense of harmonic analysis; and a state feedback controller is configured to implement GSC over the linearised process. An illustrative example is given to demonstrate the effectiveness of

Analysis and design of output feedback control systems with actuator saturation

A dynamic output feedback controller design approach based on cone complementary linearisation procedure is proposed for linear time-invariant （LTI） systems with actuator saturation. First, the estimation of the domain of attraction is given. Then, a design method to find a larger estimation of the domain of attraction is presented. In the process of design, nonconvex conditions are obtained, so a cone complementary linearisation procedure is exploited to solve the nonconvex feasibility problem. Two examples are given to illustrate the efficiency of the design method.

Effects of clipping on dry matter production and nutrients in the fernland of Hong Kong

The dry matter production and its nutrient amounts varied significantly with time and period from April to June was a favourable season for plant growth. Dry matter production declined significantly with clipping. Especially, repeated cutting of high frequencies for the long term had a severe effect on dry matter production. However, N, P, and K amounts in dry matter production did not significantly decline because the concentrations of N, P, and K in the plants increased with clipping. Repeated cutting for long term is a reason why net primary production has been depressed in the most of upland areas of southern China.

Treatment of Hydrodynamic Loading for Random Sea State

In order to employ cost effective frequency domain analysis for off-shore structures treatment of hydrodynamic loading is essential. Drag and inertia dominated, resonating and antiresonating cases under random sea states are analyzed to highlight the implications and relative merits of four salient linearization techniques.

Hydroelastic Behaviour and Analysis of Marine Structures

Hydroelasticity of marine structures with and without forward speed is studied directly using time dependent Boundary Integral Equation Method with Neumann-Kelvin linearisation where the potential is considered as the impulsive velocity potential.The exciting and radiation hydrodynamic parameters are predicted in time with transient wave Green function whilst the structural analysis is solved with Euler-Bernoulli beam method at which modeshapes are defined analytically.The modal analysis is used to approximate the hydroelastic behaviour of the floating systems through fully coupling of the structural and hydrodynamic analyses.As it is expected,it is found with numerical experience that the effects of the rigid body modes are greater than elastic modes in the case of stiff structures.The predicted numerical results of the present in-house computational tool ITU-WAVE are compared with experimental results for validation purposes and show the acceptable agreements.

Inter-relationship between approximate dynamic inversion and MRAC augmented with proportional-integral controller

Approximate Dynamic Inversion (ADI) is basically an approximation of exact dynamic inversionor feedback linearisation, which converts a nonlinear system to an equivalent linear structure.This method can be widely applied for controlling minimum phase, nonaffine-in-control systems.For applying the ADI method, a fast dynamic subsystem for deriving explicit inversion of thenonaffine equation is required. With full state feedback, ADI may be expressed in the same way asa Proportional Integral (PI) controller with only knowledge of the sign of control effectiveness andalso without any approximation. The Model Reference Adaptive Controller (MRAC) augmentedwith the PI method is an adaptive control technique where the PI parameters are updated/tunedas per the control methodology based on the MRAC-Massachusetts Institute of Technology (MIT)rule so that the plant is capable to follow the reference model. The main objective of this paperis to find the relationship between ADI and MRAC augmented with a PI controller.

Fault tolerant control in an unmanned bicycle robot via sliding mode theory

In this work,a new active fault tolerant control(FTC)is developed for an unmanned bicycle robot based on an integration between a sliding mode control(SMC),fault detection(FD),and fault estimation(FE)via a residual signal.A sliding surface in accordance with the fault tolerant sliding mode control(FTSMC)is designed for the bicycle robot to get multiple exciting features such as fast transient response with finite time convergence,small overshoot and quick stabilisation in the presence of an actuator fault.To obtain an effective performance for the FTSMC,a fault estimation system is employed and in order to attain estimation,an extended Kalman filter(EKF)as an estimator and a change detection algorithm called cumulative sum(CUSUM)as a residual evaluation function are developed.The innovative features of the proposed approach,that is FTSMC,are verified when compared with the other up‐to‐date control techniques like fault tolerant model‐based predictive control with feedback linearisation(FTMPC+FBL)and fault tolerant linear quadratic regulator with feedback linearisation(FTLQR+FBL)on an unmanned bicycle robot.

Integrated control of highway traffic flow

Several efforts have been made during recent years on the control of traffic flow using ramp metering,variable speed limit and lane change control.Most of these techniques reported significant traffic mobility improvements in macroscopic simulations,which cannot be confirmed in some microscopic simulation cases.We demonstrate that the lack of travel time improvement is due to the forced lane changes at the bottleneck which introduce a capacity drop.In this paper,a lane change controller is proposed which provides lane change recommendations to avoid the capacity drop.Combined with the lane change control,a feedback linearisation variable speed limit controller which maintains the bottleneck flow at the maximum level and coordinates with ramp metering controllers is proposed.The integrated VSL,RM and LC controller can improve system performance,manage the ramp queues and maintain the fairness between mainline and on-ramp flows.Microscopic simulations show consistent improvements under different scenarios.