Shakir Saat

Nonlinear state feedback control for a class of polynomial nonlinear discrete-time systems with norm-bounded uncertainties: An integrator approach☆

Abstract This paper investigates the problem of designing a nonlinear state feedback controller for a class of uncertain polynomial nonlinear discrete-time systems with norm-bounded uncertainties. In general, the problem of stabilising nonlinear discrete-time systems cannot be formulated as a convex problem. This is due to the fact that the Lyapunov function and the control input are not jointly convex, hence it cannot be solved by a semidefinite programming (SDP). In this paper, we propose a novel approach where an integrator is introduced to convexify this nonconvex controller design problem. Furthermore, based on the sum of squares approach, sufficient conditions for the existence of a polynomial nonlinear state feedback controller for polynomial nonlinear discrete-time systems are given in terms of solvability of polynomial matrix inequalities. These inequalities are then solved by the sum of squares (SOS) solvers. Finally, numerical examples are provided to demonstrate the validity of this integrator approach.

Contactless energy transfer using acoustic approach - A review

A coupled of ultrasonic transducer can act as a power transmission device by means of Acoustic Energy Transfer (AET). This method is relatively new method of contactless energy transfer and could be an alternative to the currently established technologies for the contactless transmission of power, such as inductive power transfer (IPT) and capacitive coupled power transfer (CPT). This paper presents a review on energy transmission through ultrasonic transducers as a source of power that has been applied by various researchers. Through this review, we hope that a better understanding of AET concept can be established and therefore can have a bright future.

A study on performances of different compensation topologies for loosely coupled inductive power transfer system

This paper investigates the performance of different compensation topologies of loosely coupled inductive power transfer system at 1MHz using Class E Amplifier. The capacitor compensation technique is regularly used in inductive power transfer to solve the problem of large leakage inductance and get the maximum power transfer when reach the resonant inductive coupling. In this paper, the analysis of efficiency of power transfer for four compensation topologies will be considered, which are primary series-secondary series (SS), primary series-secondary parallel (SP), primary parallel-secondary series (PS) and primary parallel-secondary parallel (PP). The performance of such topologies is evaluated through the simulation results.

Nonlinear H∞ feedback control with integrator for polynomial discrete-time systems☆

Abstract This paper investigates the problem of designing a nonlinear H ∞ feedback controller for polynomial discrete-time systems with and without polytopic uncertainties. The objective is to design a controller such that the ratio between the energy of the regulated outputs and the energy of the exogenous disturbance/inputs is minimized or guaranteed to be less or equal to a prescribed value. It is well known that the state dependant or parameter dependant Lyapunov function is always chosen for synthesizing polynomial discrete-time systems. This leads the solution to be nonconvex because the Lyapunov function and the controller matrix are coupled and therefore cannot be solved by semidefinite programming (SDP). Hence, in this paper, an integrator is proposed to be incorporated into the controller structure. In doing so, the coupling of Lyapunov function and controller matrix can be eliminated effectively. This somehow simplifies the numerical solution of the problem. Then, by using SOS decomposition approach, sufficient conditions for the existence of the proposed controller are provided in terms of solvability of the state-dependent linear matrix inequalities (SDLMIs) which can be solved by SDP. A tunnel diode circuit is used to demonstrate the effectiveness of this integrator approach.

Robust Nonlinear H∞ State Feedback Control of Polynomial Discrete-Time Systems: An Integrator Approach

This paper investigates the problem of designing a nonlinear H∞ state feedback controller for polynomial discrete-time systems with norm-bounded uncertainties. In general, the problem of designing a controller for polynomial discrete-time systems is difficult, because it is a nonconvex problem. More precisely, in general, its Lyapunov function and control input are not jointly convex. Hence, it cannot be solved by semidefinite programming. In this paper, a novel approach is proposed, where an integrator is incorporated into the controller structure. In doing so, a convex formulation of the controller design problem can be rendered in a less conservative way than the available approaches. Furthermore, we establish the interconnection between robust H∞ control of polynomial discrete-time systems with norm-bounded uncertainties and H∞ control of scaled polynomial discrete-time systems. This establishment allows us to convert the robust H∞ control problems to H∞ control problems. Then, based on the sum of squares (SOS) approach, sufficient conditions for the existence of a nonlinear H∞ state feedback controller are given in terms of solvability of polynomial matrix inequalities (PMIs), which can be solved by the recently developed SOS solvers. A tunnel diode circuit is used to demonstrate the validity of this integrator approach.

Altitude controller design for multi-copter UAV

This paper discusses on attitude control of a quadcopter unmanned aerial vehicle (UAV) in real time application. The paper describes the controller design method for the hovering control of UAV automatic vertical take-off system. In order to take-off the quadcopter and stable the altitude, PID controller has been designed. The scope of study is to develop an altitude controller of the vertical take-off as realistic as possible. The quadcopter flight system has nonlinear characteristics. A simulation is conducted to test and analyze the control performance of the quadcopter model. The simulation was conducted by using Mat-lab Simulink. On the other hand, for the real time application, the PCI-1711 data acquisition card is used as an interface for controller design which routes from Simulink to hardware. This study showed the controller designs are implemented and tuned to the real system using Real Time Windows Target approach by Mat-Lab Simulink.

Design of Capacitive Power Transfer Using a Class-E Resonant Inverter

This paper presents a capacitive power transfer (CPT) system using a Class-E resonant inverter. A Class-E resonant inverter is chosen because of its ability to perform DC-to-AC inversion efficiently while significantly reducing switching losses. The proposed CPT system consists of an efficient Class-E resonant inverter and capacitive coupling formed by two flat rectangular transmitter and receiver plates. To understand CPT behavior, we study the effects of various coupling distances on output power performance. The proposed design is verified through lab experiments with a nominal operating frequency of 1 ㎒ and 0.25 ㎜ coupling gap. An efficiency of 96.3% is achieved. A simple frequency tracking unit is also proposed to tune the operating frequency in response to changes in the coupling gap. With this resonant frequency tracking unit, the efficiency of the proposed CPT system can be maintained within 96.3%–91% for the coupling gap range of 0.25–2 ㎜.

Capacitive power transfer with impedance matching network

This paper presents the development of a new wireless power transfer technique using capacitive coupling. Capacitive power transfer (CPT) system has been introduced as an attractive alternative to the traditional inductive coupling method. This is due to the CPT benefits of simple topology, fewer components, better EMI performance and robustness to surrounding metallic elements. In this work, a Class-E resonant inverter together with impedance matching network has been utilized as a high frequency ac power source because of its ability to perform the dc-to-ac inversion efficiently. It helps the CPT system to achieve a maximum power transfer. The CPT system is designed and simulated by using Proteus 8 Professional software. The validity of the proposed concept has been verified by conducting a laboratory experimental CPT system. It generates a 9.5W output power through a combined interface (PCB plate) capacitance of 2.82nF, at an operating frequency of 1MHz, with 95.44% efficiency. Also, the proposed CPT system with impedance matching network allow variation to the load while maintaining the efficiency over 80%.

Nonlinear filter design with integrator for a class of polynomial discrete-time systems

In this paper, we attempt to design a filter to estimate the state of polynomial discrete-time systems. In this work, a global filter design method for polynomial discrete-time systems by using SOS-SDP based is established without any assumptions about nonlinear terms of the error dynamics. In our work, to ensure a convex solution to the filter design problem can be obtained, an integrator is incorporated into the filter structure. This paper provides a potential solution to the filter design problem for polynomial discrete-time systems. Unfortunately, the price we pay is the computational burden due to a very large SDP size yields from the proposed method. The effectiveness of the proposed method is confirmed through a simulation example.

Nonlinear observer design with integrator for a class of polynomial discrete-time systems

This paper presents the observer design to control and at the same time estimate the state of polynomial discrete-time systems. In general, to design observer for polynomial discrete-time system is difficult because the solution is nonconvex. More precisely, it is a nonconvex problem due to the relationship between the Lyapunov function and the observer gain is not jointly convex. Hence, it cannot be possible to be solved via semidefinite programming (SDP). In this work, to ensure a convex solution to the observer design problem can be obtained, an integrator is incorporated into the observer structure. By doing this, a convex solution can be guaranteed. The observer gains are then computed using SOS-SDP techniques.