Model-based synthesis of nonlinear PI and PID controllers

Structural analysis of fuzzy controllers with nonlinear input fuzzy sets in relation to nonlinear PID control with variable gains

Structural analysis of fuzzy controllers with nonlinear input fuzzy sets in relation to nonlinear PID control with variable gains*1

Gyro stabilizes tank gun in action

This paper presents a practical implementation for a new formula of nonlinear PID (NPID) control. The purpose of the controller is to accurately trace a preselected position reference of one stage servomechanism system. The possibility of developing a transfer function model for experimental setup is elusive because of the lack of system data. So, the identified model has been developed via gathering experimental input/output data. The performance of the enhanced nonlinear PID (NPID) controller had been investigated by comparing it with linear PID controller. The harmony search (HS) tuning system had built to determine the optimum parameters for each control technique based on an effective objective function. The experimental outcomes and the simulation results show that the proposed NPID controller has minimum rise time and settling time through constant position reference test. Also, the NPID control is faster than the linear PID control by 40% in case of variable position reference test.

This paper investigates the performance of adaptive particle swarm optimization (APSO) algorithm to find the best optimal gain parameters (Kp, Ki, Kd) in linear PID (L-PID) and nonlinear PID (NL-PID) controllers for the trajectory control of a nonlinear dynamical system (NLDS). Mathematical modeling, stability and performance analysis of a NLDS are being carried out with L-PID and NL-PID controllers. It is found that the APSO based tuning of NL-PID controller provides better tracking of NLDS than L-PID controller in respect of its search domain, premature convergence, and computational efficiency. Simulation analysis of various variables of controllers and system response such as error, cost function, and response of NLDS and their comparison to that of APSO tuned L-PID controller is described.

This paper addresses the speed control of a series DC motor. Based on the nonlinear motor system dynamics, the analysis and design of two novel speed controllers are presented, which are nonlinear PI and integrator backstepping controllers. The speed response following step changes in speed reference and load torque, using the proposed nonlinear controllers and traditional linear PI controllers, is compared to evaluate their merits. It is shown that the proposed controllers can provide stable and more excellent dynamic control performance than that of the traditional PI controllers in terms of rise time, overshoot and steady state error.

Two-way shear failure of slabs is a sudden one, which has catastrophic outcomes. Slabs with large spans may be subjected to in-plane tensile forces due to thermal or earthquake loading. There is a lack of agreement between various design codes regarding the significance of in-plane tensile forces on the two-way shear strength. Two-way shear failure of slabs is a sudden one, which has catastrophic outcomes. Slabs with large dimensions may be subjected to in-plane tensile forces due to restraint or earthquake loading. There is a lack of agreement between various design codes regarding the significance of in-plane tensile forces on the two-way shear strength. The purpose of this study is to explore, propose a simplified two-way shear strength model, which includes the effect of in-plane tensile forces on the strength. A review for the experimental investigations, existing models, design codes for two-way shear of slabs is presented, with emphasis on in-plane tensile forces. The loading method used in the current experimental testing is misleading, where the two-way shear and the in-plane forces are independent. A comparative study was conducted between the existing formula and design codes for this case. The comparison between different codes with the experimental results show that the new proposed Eurocode design code was found to be the most accurate one. However, it did not include the effect of the in-plane tensile forces in a physically sound manner. In addition, more full testing of concrete slabs under combined two-way shear and tensile forces are required to refine this existing two-way shear design code provisions or develop new formulas or mechanical models.

Both linear PID controllers and fuzzy controllers are designed and implemented for a boost converter. Comparison between the two controllers is made in the aspect of design, implementation and experimental results. Design of fuzzy controllers is based on heuristic knowledge of the converter and tuned using trial and error, while the design of linear PID and PI controllers is based on the frequency response of the boost converter. Implementation of linear controllers is quite straightforward, while implementation of fuzzy controllers has its unique issues. A comparison of experimental results indicates that the performance of the fuzzy controller is superior to that of the linear PID and PI controllers. The fuzzy controller is able to achieve faster transient response, has more stable steady-state response, and is more robust under different operating points.

A nonlinear PID controller with applications

The photovoltaic (PV) system’s nonlinear nature, uncertainty in temperature, and light intensity in the environment are responsible for the fluctuation of the maximum power point (MPP). Many maximum power point tracking (MPPT) algorithms are proven effective in the literature, including use of artificial intelligence. Proportional integral derivative controller and fuzzy controllers found effective to track MPP. Using the combination of Fuzzy-PID controller, swiftly adapt to changes in the atmosphere to confirm the solar array is continually operating at its highest efficiency with MPP. Easy and effective oscillation elimination is possible with PID control. To regulate the maximum power of the PV system combination of Fuzzy-PID self-tuning controllers is found effective.The goal is to enhance a PV system’s dynamic response to in presence of irradiation and temperature fluctuations. For tuning Fuzzy logic controller (FLC), gain scheduler values of the proportional, integral, and derivative constants are fundamental. The design processes for non-linear conventional PID controllers, FLC, and series combination of Fuzzy-PID controller are discussed. It compares the traditional PID controller, FLC, and Fuzzy-PID controller. The comparison of outputs produced for PID, FLC, and series Fuzzy-PID controller confirms the effectiveness of the algorithm. Use of Fuzzy controller helps in self-tuning of PID controller constant value. MATLAB/Simulink based environment used to perform the simulations.

Nonlinear PID (N-PID) Controller for SSSP Grid Connected Inverter Control of Photovoltaic Systems

Rear-cabin pressure control system of high-altitude test facility has the characteristics of large time-delay, nonlinearity and strong disturbances. In China, the rear-cabin pressure control system uses the conventional PID control method which can’t nonlinearly regulate pressure very well; especially in engine transient experiments, it can’t automatically turn PID parameters to adapt the changes of system’s nonlinearities, which has seriously affected the dynamic regulation and control accuracy of the rear-cabin pressure. Therefore, in this paper, firstly the dynamics of hydraulic butterfly valve is modeled and the nonlinear characteristics of exhaust diffuser are analyzed and the simulation model of the rear-cabin pressure control system is established. Secondly, the nonlinear PID controller is developed based on extremum seeking and its parameters are turned online according to the pressure errors between the setting valves and system outputs of the pressure system by minimizing the cost function. Finally, with and without engine flow disturbances, some simulation results of the linear and nonlinear PID control are given for pressure regulation to show that the proposed nonlinear PID based on extremum seeking can not only turn the controller parameters online, but also reject time-varying and large amplitude disturbances, so it has effectively enhanced the nonlinear adaptability of controller and improved the control accuracy of transient responses of the rear-cabin pressure control system.

International audience

The nonlinear fuzzy PID control strategy, which combines nonlinear control, fuzzy control and PID control, is put forward in this paper to deal with the control of a class of nonlinear and large inertia plants under complicated and large variation conditions. The proposed control strategy can adjust control parameters timely and appropriately according to the dynamic characteristics of the systems, so as to achieve fast transient response and good steady-state accuracy. Moreover, the control strategy has good robustness and self-adaptive ability to the changes of model parameters. Take the case of the three-tank water system, the control strategy is investigated by simulation and experimentation. Experimental results, which agree with simulation results, show the control strategy suggested in the paper is correct and feasible. The design and implementation of it is simple and convenient, and it may have important reference value for the control of a class of continuous nonlinear and large inertia plants such as heating furnace and multi-capacity level plant in complicated conditions.

Typical Takagi–Sugeno PI and PD fuzzy controllers: analytical structures and stability analysis