Practical robust control using Self-regulation Nonlinear PID controller for pneumatic positioning system

This paper investigates the robustness of the pneumatic positioning system controlled by Self-regulation Nonlinear PID (SNPID) controller. This controller is executed by utilizing the characteristic of rate variation of the nonlinear gain that are readily available in Nonlinear PID (NPID) controller. A Self-regulation Nonlinear Function (SNF) is used to reprocess the error signal with the purpose to generate the value of the rate variation, continuously. Simulation and experimental tests are conducted. The controller is implemented to a variably loads and pressures. The comparison with the other existing method i.e. NPID and conventional PID are performed and evaluated. The effectiveness of SNPID + Dead Zone Compensator (DZC) has been successfully demonstrated and proved through simulation and experimental studie

Application of electromagnetic sensor in electro-pneumatic actuator displacement control under variable loads conditions: experimental analysis

Dead-zone is a major issue that degrades the performance of the positioning control system in the pneumatic proportional valve control system. In order to address the issue, a switching inverse dead-zone compensator was incorporated to the pole-placement control of the Electro-Pneumatic Actuator (EPA) systems driven by a proportional directional control valve. The focus of this study is to do an experimental analysis to evaluate the robustness of the system under varying loads and varying position distances. Electromagnetic sensor is used to measure the displacement of the pneumatic cylinder piston movement. In this paper, the EPA model was chosen as a Hammerstein model that contains an Autoregressive with exogenous term (ARX) model and a nonlinear dead-zone model. The ARX model is estimated using the Recursive Least Square (RLS) method and the nonlinear model is obtained by using the Particle Swarm Optimization (PSO) method. The position tracking of the EPA system adapts to the pole-placement control law and is combined with switching inverse dead-zone in a feedforward manner. Experimental investigations were carried out for varying loads from 3.1 kg to 23.5 kg and varying position distances from 25 mm to 200 mm. Experimental results show that the EPA system controlled by the proposed controller is able to perform no overshoots for loads weighing less than 23.5 kg for all tested position distances. In addition, the proposed method achieved a steady state position error of 0.46 mm, a rise time of 0.21 s and a settling time of 0.49 s. The results demonstrated that as the load weight and position distance increased, transient time increased. However, the proposed method has successfully controlled the positioning of the EPA systems for all tested load weight and position distance

PSO-based PID controller design for an energy conversion system using compressed air

U ovom se radu predlaže optimalni kontrolni algoritam za rješavanje problema niske performanse zbog nelinearnih značajki pneumatskog motora u sustavima za pretvorbu energije pomoću stlačenog zraka. Učinkovitost predloženog algoritma se ispituje na sustavu za pretvorbu energije koji uključuje kompresor, proporcionalni ventil, pneumatski motor (PM), generator istosmjerne struje s trajnim magnetom (PMDC) i kontrolnu karticu. Kontrolna funkcija sustava provodi se pogonjenjem proporcionalnog ventila s kontrolnim signalima što se postiže ovisno o greški napona na izlazu PMDC generatora. U toj konstrukciji, optimalni proporcionalni-integralni-derivativni (PID) regulator izravno podešava vlastite parametre pojačanja algoritmom optimizacije roja čestica - particle swarm optimization (PSO) u skladu s radnim uvjetima primijenjenog sustava. U svrhu promatranja učinaka PID-regulatora zasnovanog na PSO na rad sustava, sustav za pretvorbu energije se kontrolira PID regulatorom diskretnog vremena. Eksperimentalni rezultati pokazuju da PID regulator zasnovan na PSO osigurava robustniju regulaciju rada nego PID regulator diskretnog vremena kod različitih radnih uvjeta.In this study, an optimal control algorithm is proposed to overcome low performance problems arising from the non-linear characteristics of pneumatic motor in compressed air-based energy conversion systems. The effectiveness of the proposed algorithm is tested on an energy conversion system which includes a compressor, a proportional valve, a pneumatic motor (PM), a permanent magnet direct current (PMDC) generator and a control card. The control function of the system is carried out by driving the proportional valve with the control signals which is obtained depending on the PMDC generator output voltage error. In this structure, an optimal proportional-integral-derivative (PID) controller which tunes on-line its own gain parameters by particle swarm optimization (PSO) algorithm according to the operating conditions of the system used. In order to observe the effects of PSO-based PID controller on the system performance, the energy conversion system is also controlled by a discrete time PID controller. The experimental results show that PSO-based PID controller provides more robust control performance than discrete time PID controller under various operating conditions