Nonlinear PID Pressure Control Based on Extremum Seeking

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 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.

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.

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

Model-based synthesis of nonlinear PI and PID controllers

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

This paper presents two nonlinear PID (NPID) controllers which control the glycol temperature of a regasification system for LNG-fuelled engines. The NPID controllers have a parallel structure of the three nonlinear P, I, D actions or the linear P, D actions and nonlinear I action. A nonlinear function is employed to scale the error as input of the integral and implemented as a Takagi-Sugeno (T-S) fuzzy model. The controller parameters are optimally tuned by using a genetic algorithm. Furthermore, the stability problem of the overall system is verified based on the circle criterion. A set of simulation works is carried out to validate the efficiency of the two proposed controllers.

A nonlinear PID controller with applications

International audience

Nonlinear proportional-integral-derivative (NPID) is realized by modulating the control gains of a conventional linear controller in response to system state or error. Performance benefits such as increased damping or reduced tracking error have been experimentally demonstrated. Previous results (2000) have established Lyapunov stability of NPID control for full-state knowledge and for special cases of partial-state knowledge; but the general problem of stability with arbitrary state knowledge remained unsolved. In the present work, design methods for NPID control are extended to the case of arbitrary partial-state knowledge. Given any combination of a stabilizable linear system and NPID control law, an upper bound on control effort can be determined for which global asymptotic stability is assured. The result is based on a Lyapunov stability proof and is applied to establish the stability of NPID control for the Sarcos dexterous manipulator.

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.

Adjusting the traditional PID controller parameters requires the expert’s experience. Sometimes, the traditional linear PID controller can't balance the dynamic and static performance of the system, and it can’t effectively control the object when the object parameters change. We propose a nonlinear PID controller, which uses state transition algorithm (STA) to tune the parameters of nonlinear PID controller, and uses data-driven (DD) to enable the system to identify different object parameters and adopt the corresponding controller. Simulation results show that the proposed controller effectively improves the control effect of the above problems.

Because of the wind power generation has good economic and social benefits, which has been aroused more and more people's attention. The variable pitch control has an important part in the wind turbine. The indexes of the variable pitch has great influence on the dynamic performance with the unit, which can become an important index to measure the performance of the wind turbine. Due to the non-linearity and randomness of the variable pitch control system, the selection of the control strategy becomes very important. By establishing the function of the PID controller and the input deviation, which the PID controller has the nonlinear gain variable of the three parameters. Adopting the nonlinear PID control strategy according to the change of the different wind speed. The simulation results show that the dynamic performance of the nonlinear PID control is better than the traditional PID control, and it also can improve the speed and accuracy of variable pitch control system.

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.