Validation of the KC autotuning principle on a multi-tank pilot process

PIDs are the most widely used controllers in industrial applications. This particular interest generates on-going research regarding simplified tuning methods appealing to the industrial user. Such methods refer also to a fast design of PID controllers in the absence of a mathematical model of the process. Autotuners represent one way of achieving such a fast design. In this paper, the experimental validation of a previously presented direct autotuner is presented. The autotuning method requires only one simple sine test on the process to compute the PID controller parameters. The case study consists in the Quanser Six Tanks Process. Comparisons with other popular tuning methods are also presented. The results show that the proposed autotuning method is a valuable option for controlling industrial processes

Universal direct tuner for loop control in industry

This paper introduces a direct universal (automatic) tuner for basic loop control in industrial applications. The direct feature refers to the fact that a first-hand model, such as a step response first-order plus dead time approximation, is not required. Instead, a point in the frequency domain and the corresponding slope of the loop frequency response is identified by single test suitable for industrial applications. The proposed method has been shown to overcome pitfalls found in other (automatic) tuning methods and has been validated in a wide range of common and exotic processes in simulation and experimental conditions. The method is very robust to noise, an important feature for real life industrial applications. Comparison is performed with other well-known methods, such as approximate M-constrained integral gain optimization (AMIGO) and Skogestad internal model controller (SIMC), which are indirect methods, i.e., they are based on a first-hand approximation of step response data. The results indicate great similarity between the results, whereas the direct method has the advantage of skipping this intermediate step of identification. The control structure is the most commonly used in industry, i.e., proportional-integral-derivative (PID) type. As the derivative action is often not used in industry due to its difficult choice, in the proposed method, we use a direct relation between the integral and derivative gains. This enables the user to have in the tuning structure the advantages of the derivative action, therefore much improving the potential of good performance in real life control applications

Autotuning method for a fractional order controller for a multivariable 13C isotope separation column

The preferred controller design technique in industrial applications is based on autotuning procedures that do not involve knowledge about an actual mathematical model of the process. In this paper, a novel autotuning method for designing fractional order controllers is addressed. The proposed technique is simple and efficient. Previous research with respect to autotuning methods for fractional order controllers has considered exclusively the case of a single-input single-output process. However, in this paper, a multivariable case study is preferred. The simulation results demonstrate the validity of the design technique

Alternative implementations of a fractional order control algorithm on FPGAs

Traditionally, microprocessor and digital signal processors have been used extensively in controlling simple processes, such as direct current motors. The Field Programmable Gate Arrays (FPGA) are currently emerging as an alternative to the previously used devices in controlling all sorts of processes. The fractional order proportional-integrative control algorithm has the advantage of enhancing the closed loop performance as compared to traditional proportional-integrative controllers, but the implementation requires a higher number of computations. Implementations of control algorithms on FPGAs are nowadays much faster than implementations on microprocessors. This allows for a more accurate digital realization of the fractional order controller. The paper presents nine alternative implementations of such control algorithm on two different FPGA targets. The experimental results, considering DC motor speed control, show that double, fixed-point and integer data representation may be used efficiently for control purposes

Fractional order control for the temperature loop in a chemical reactor

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Theoretical analysis and experimental validation of a simplified fractional order controller for a magnetic levitation system

Fractional order (FO) controllers are among the emerging solutions for increasing closed-loop performance and robustness. However, they have been applied mostly to stable processes. When applied to unstable systems, the tuning technique uses the well-known frequency-domain procedures or complex genetic algorithms. This brief proposes a special type of an FO controller, as well as a novel tuning procedure, which is simple and does not involve any optimization routines. The controller parameters may be determined directly using overshoot requirements and the study of the stability of FO systems. The tuning procedure is given for the general case of a class of unstable systems with pole multiplicity. The advantage of the proposed FO controller consists in the simplicity of the tuning approach. The case study considered in this brief consists in a magnetic levitation system. The experimental results provided show that the designed controller can indeed stabilize the magnetic levitation system, as well as provide robustness to modeling uncertainties and supplementary loading conditions. For comparison purposes, a simple PID controller is also designed to point out the advantages of using the proposed FO controller

HIL real-time simulation of a digital fractional order PI controller for time delay processes

Fractional order control has been used extensively in the last decade for controlling various types of processes. Several design approaches have been proposed so far, the closed loop performance results obtained being tested using different simulation conditions. The hardware-in-the-loop (HIL) real-time simulation offers a more reliable method for evaluating the closed loop performance of such controllers prior to their actual implementation on the real processes, such HIL simulation being highly suitable especially for complex, hazardous processes in which human and equipment errors should be avoided. The present paper proposes a hardware-in-the-loop real-time simulation setting for a digital fractional order PI controller in a Smith Predictor structure. The designed control strategy and fractional order controller is then tested under nominal and uncertain conditions, considering a time delay process