Keywords: Control Education
Abstract: This paper presents m-PaRoLa, an educational virtual laboratory that consists of Javascript simulations for analyzing parallel robots. These simulations can be run indistinctly on web browsers of desktop computers or mobile devices (smartphones, tablets), which turns m-PaRoLa into a mobile virtual laboratory ready to be integrated in m-learning methodologies for teaching robotics and mechanisms. The presented simulations, which are highly intuitive and visual, allow the user to analyze diverse kinematic problems of parallel robots.

Keywords: Control Education, Computer and Telematics
Abstract: This paper explores the possible steps to support a larger number of students in a Massive Open Online Lab (MOOL) dedicated to control education. The current solutions to support a ratio greater than 1:1 (1 student accessing 1 setup) is either to multiply the setups or to limit the time the students access the setup. This paper first describes the current EPFL MOOL infrastructure and its associate MOOC for control offered to bachelor engineering students. It then provides analysis of students access and activity. Finally based on the analysis, various options to support more students are explored.

Keywords: Control Education
Abstract: This paper presents a ongoing project to develop new interactive books for control education. The novelty of the proposed idea is to merge web-based solutions with LaTex text into a epub format. In such a way, classical interactive tools for control education are combined with static text and thus interactive books are created, being compatible with standard e-book readers. A book chapter about the teaching of second-order processes is presented as example to show the different steps and the results of the proposed idea.

Keywords: Control Education, Control Design, Optimal Control
Abstract: The Performance Portrait Method enables to visualize influence of chosen control parameters on the loop performance of the selected dynamical system with given interval parameter uncertainties. The knowledge of this behavior can help to analyze and tune control algorithm and to fulfill expected requirements as far as robustness and control quality. The presented paper introduces a new web tool that in an interactive way enables to design filtered 2DOF PI controller for the integral plus dead time system models on the base of the performance portrait method. For a performance portrait calculated once in the 3-5D parameter space it enables to find optimal robust controller tuning. For given plant parameter uncertainties it yields the fastest possible transient responses satisfying with chosen tolerances the shape related constraints at the plant input and output. A web application developed to illustrate the problem offers much richer visual information than it is possible to offer by standard publications, interactivity and dynamical effects. The backend of the application is driven by Matlab software. This environment is used both for calculation of the performance portrait and for simulation of transients of the considered feedback control structure.

Keywords: Control Design
Abstract: In this paper, the mechanism and method of using disturbance observer (DOB) to eliminate the disturbance are studied and applied to the control of position servo system. The DOB consists of an inverse model of the controlled object and a filter, and suppresses the external disturbance acting on the servo system. Based on the traditional proportional integral derivative (PID) controller, simulations on MATLAB/Simulink and tests on Quanser semi-physical experiment platform are performed for the PID controller with DOB and without DOB. Simulation and experimental results show that the introduction of DOB can effectively suppress the external disturbance and improve the dynamic response performance and stability of the servo system.

Keywords: Mechatronic Systems, Control Design
Abstract: In this paper a fast automatic tuning methodology for velocity controllers of mechatronic systems is proposed. In order to be applicable in general, the method takes into account the position, velocity and torque constraints of the motion control system and it requires a minimum intervention of the operator. Further, it can be implemented also with small computational capabilities which makes it suitable for industrial drives. Simulation results show the effectiveness of the technique.

Keywords: Mechatronic Systems, Linear Control Systems
Abstract: This paper deals with the use of a load acceleration feedback to overcome fundamental performance limitations of elastic servo drive systems that occur when employing a standard PI velocity controller. Structured H-infinity optimization approach is used to develop an optimal control strategy consisting of a PI controller and a static acceleration feedback. Qualitative and quantitative analysis of potential benefits for the case of a two-mass system is provided. Effects of higher resonance modes is studied as well. Experimental results demonstrate the application of the proposed methodology to a flexible arm manipulator.

Keywords: Mechatronic Systems
Abstract: This paper deals with the control of a collaborative robot manipulator with series elastic actuators. In particular, robust tuning rules for cascade control of the joints are presented. Both the motor velocity and link position control loops are considered. The proposed tuning rules allow the online computation of robust control parameters to cope with the different link reflected inertia. Experimental results show the effectiveness of the method in real applications.

Keywords: Control Design, Non Linear Control Systems
Abstract: Hybrid controllers are capable of improved performance over their linear counterparts. In particular, reset controllers like the PI+CI are capable of fast flat response for lag dominant plants. Grid connected power converters especially interfacing energy storage systems to grids are required to have fast response to varying load demands to ensure minimum variation in grid parameters. Application of PI+CI controllers in such systems can improve their performance. In this work the improvement brought about by use of PI+CI controller employed for energy storage system power converters is highlighted by comparing it with PI controller based system under load variations. A DC microgrid with Fuel cellsupercapacitor based storage elements are considered here. The design criteria and simulation results are presented here.

Keywords: Linear Control Systems, Control Design, Distributed Parameter Systems
Abstract: This paper makes a discussion on the control of light in landscape offices. This is a feature of modern office buildings, with increasing incidence as the number of employees increase while individual space allocation decreases. This can have already an impact on the efficiency and versatility of coping with stress situations of the employees. Apart from the stress induced by the lack of space and privacy, the light level is yet another important factor. Poor light or extreme illumination, or even more relevant: periodic shadow disturbance (i.e. windmills) are all increasing factors of stress levels. Control of illumination in a closed environment seem to be a feasible solution, but perhaps not very useful for the overall mood of the employee. Windows and possibility to see green patches, sunlight, have significant positive influence on the overall working conditions. Although easy to implement and broadly available in industrial lighting components, PID control has some limitations which we discuss here.

Keywords: Control Design, Non Linear Control Systems
Abstract: The present work describes the results obtained from a nonlinear PID control (NPID) approach for the pitch control with top tower active damping of a large wind turbine. The control algorithm is implemented by using a well-known approach based on hyperbolic secant functions. A nonlinear PID controller and a nonlinear P controller are used for the collective pitch control and the active tower damping, respectively. As simulation platform, the 5-MW reference turbine developed by NREL and the software FAST are used. Results show that the NPID approach can provide significant improvements in the control performance in comparison to the classic control approach, in particular when the wind speed goes far from its rated value.

Keywords: Control Design, Adaptive and Learning Systems, Modelling, Identification and Signal Processing
Abstract: The present study proposes a new approach to a data-driven PID control design method based on one-shot closed-loop input and output data. Even if the proposed controller is designed using only one-shot data, both the prescribed robust stability and tracking performance optimization are attained. The proposed control law is designed by solving a constrained optimization problem, in which the robust stability as a constraint condition is designed by a sensitivity function estimated using the discrete-time Fourier transform, and the performance function defined using a fictitious reference is minimized. As a result, the proposed method provides trade-off design between the tracking performance and robust stability, where the robust stability is arbitrarily selected depending on the model perturbation. The effectiveness of the proposed method is demonstrated through numerical examples.

Keywords: Control Design, Linear Control Systems
Abstract: A new and freely available model-based PID design tool for Matlab is introduced. It can be used to solve Maximal Integral Gain Optimization (MIGO) and (load) Integral Absolute Error (IAE) problems. Robustness is ensured through Hinf constraints on the closed-loop transfer functions. A Youla parameter (Q design) method for comparison with the optimal linear time- invariant (LTI) controller for the considered IAE optimization problem is presented. Several realistic design examples are provided, in which the tool is used to compare achievable PID and optimal LTI controller performance, to illustrate whether PID is a good choice for a given combination of process dynamics and closed-loop robustness requirements.

Keywords: Control Design, Linear Control Systems
Abstract: In this paper, the design of a performance-varying multivariable Proportional-Integral-Derivative (PID) controllers is presented. The main objective is to provide a framework for changing online the closed-loop behavior of the controlled system using the shifting pole placement approach. In order to carry out this target, the PID design problem is transformed into a static output feedback design problem which is analyzed through the linear parameter-varying (LPV) paradigm. An academic example is used to demonstrate the effectiveness of the proposed approach.

Keywords: Linear Control Systems, Control Design
Abstract: Feedforward control schemes to compensate for disturbances are very well known in process control. In those control approaches, PID controllers are usually considered in the feedback loop, where nominal design for both feedback and feedforward controllers are commonly performed. This paper presents a robustness analysis to study how uncertainties can affect the classical feedforward control scheme. Afterwards, a robust PI controller is designed by using Quantitative Feedback Theory to account for these uncertainties and to fulfill robust specifications for the regulation control problem. Results based on frequency and time domains are presented.

Keywords: Linear Control Systems
Abstract: In this paper we propose a methodology to evaluate the performance of decentralized PID controllers for two-inputs-two-outputs processes and to retune the parameters. In particular, the model of the process is estimated based on a technique that exploits the final value theorem. Then, an evolutionary algorithm is applied in order to find the Pareto front by considering a multi-objective optimization problem. Finally, the performance obtained with the current tuning is compared with the optimal ones and, in case it is necessary, the PID parameters are retuned accordingly. A procedure to achieve the Nash optimal point is also proposed.

Keywords: Control Design, Optimal Control
Abstract: In this paper, a PID tuning method for integrating processes having time delay and inverse response is presented. The method is based on the stability boundary locus method and geometrical center (WGC) approach. The systematic procedure of the method is first to obtain the stability region in the PI controller parameters (proportional gain: kp and integral gain: ki) plane according to derivative gain (kd) using the stability boundary locus method and then to find the weighted geometrical center point of this region. The WGC controllers are obtained by using different values of kd. Simulation examples have demonstrated that PID controller designed by using the proposed method gives good results.

Keywords: Control Design
Abstract: Multidisciplinary design optimisation (MDO) has shown to be a valuable tool for designers when different fields converge in the design phase. Where classical approaches perform a sequential optimisation procedure, it seeks to exploit synergies between interacting subsystems, with the aim of getting a better overall. In this paper, we analyse and compare three different MDO approaches considering the tuning of a Proportional-Integral (PI) controller and plant design simultaneously. As conflicting objectives might appear, we compare such approaches using multi-objective optimisation. With the provided example, advantages and drawbacks are highlighted, in order to provide an insight about the applicability of such approaches.

Keywords: Optimal Control, Control Design, Control Education
Abstract: A simple design method for robust PD controllers is presented for systems including integral action. The design method is based on a multi-criteria optimal control formulation, which is easily solved by a few lines of MATLAB code. Most criteria are based on Hinfsaasaa measures, but since the focus is on reference signal tracking and not load disturbance compensation, the settling time is also included as a relevant performance measure. Since a PD controller is equivalent to a lead filter, the optimal PD controller is compared with ordinary text book design rules for lead filters. More specifically, it is shown that the common recommendation to place the mid frequency of the lead filter at the desired gain crossover frequency often gives bad servo performance. The suggested optimal solution, still including robustness and control activity adjustments, is on the other hand a simple and flexible design method for arbitrary plants including integral action.

Keywords: Control Education, Linear Control Systems
Abstract: General closed form expressions of linear continuous time system responses of an arbitrary order are derived, by first relating them to basic responses, i.e., responses corresponding to unity numerator transfer functions. Those are then related to the fundamental solutions of the underlying differential equations. These expressions apply to all systems without any restrictions on the poles or the zeros, further the systems may be noncausal. We derive responses for all regular types of inputs, impulse, step, ramp, parabola, etc., in addition for all generalized derivatives of the impulse. All the presented results have a direct counterpart in results presented in Sigurdsson et al. (2017) on discrete time systems based on the fundamental solution of the associated difference equation. Efficient evaluations of the fundamental solutions along with their derivatives and integrals can thus be extended to the responses and are readily implemented, e.g., as Matlab functions. Such results may be presented symbolically as functions of time or evaluated numerically at any sequence of times without time stepping.

Keywords: Control Education, Control Design, Computers for Control
Abstract: The use of videos is a valuable and powerful tool which may significantly contribute to change and improve teaching and learning methods. Lecturers can made their own videos addressing specific topics suitable to fulfill their student’s needs. These videos can address control engineering syllabus as well as complementary topics. This paper proposes using video as a tool to introduce the particle swarm optimization algorithm to students within a digital PID control simulation experiment. The experience preliminary results and feedback received from students are quite positive.

Keywords: Control Education, Control Design, Non Linear Control Systems
Abstract: This paper presents an experimental study of different non linear PI controllers using an academic platform based on an Air Levitation System. The comparison is based on common performance indexes, computed over the data extracted from the experiments. The results verify that, in addition to the PID controller in its classic form, several non-linear modifications can be considered to cope with different control needs, such as optimization on the number of control actions, or go beyond the restrictions that linearity impose on the performance that can be obtained by a PID controller.

Keywords: Control Education
Abstract: The Online Dynamical Systems and Control (ODYSC) web application has been developed for the introductory dynamics and control courses taught to engineers and business engineering of Ghent university, accessible through http://www.odysc.ugent.be/. Generally speaking, the advantage of web apps over conventional software is the compatibility between OS and devices, as only a browser is required. Recently, students bring a mobile phone to lectures. While these are often used by the students themselves as a distraction, they are actually very powerful computers capable of performing simulations of dynamical systems. Because of this, ODYSC has been designed to be responsive, working equally well on both mobile phone as on a laptop or PC. While ODYSC can serve as a distance learning tool, it can also be employed during classical lectures. While the teacher explains new concepts in dynamics or control, these can immediately be made clear through simulations on the student's phone. Before, the amount of students attending these courses were a practical limitation for organizing computer labs. Even if such infrastructure exists, the software used requires the students to code in a new language, which they are often not motivated enough to do for a single lab, or the software is associated with costly or complicated licensing. ODYSC requires no special infrastructure but a device with a browser which students themselves bring anyway. ODYSC is still in full development and for now can perform open loop and closed loop simulations on LTI systems, and plot bode plots of the system.

Keywords: Control Education, Intelligent Autonomous Vehicles
Abstract: In STEM subjects, interactive laboratories are one of the most widely used tools for students to acquire practical knowledge. These laboratories allow them to modify system parameters and analyze the outputs in real time. In control engineering, these laboratories include different predefined controllers with which the student must experiment to study their operation. However, these laboratories usually do not include functions that allow students themselves to create their own controller. This work presents an interactive virtual laboratory to control mobile robots developed in JavaScript. Mobile robots are an attractive platform for students where they can analyze, test and understand fundamental concepts that are difficult to explain from a theoretical point of view. This environment allows the student to generate their own experiments (general statements, controllers, steps to follow over time) and test them with the simulator. For example, they can design their own position controllers and they can compare different PID-type control strategies in real time. Besides, this environment is open and configurable, so the teacher can decide the available features for each experiment depending of the learning goals.

Keywords: Control Education, Chemical Process Control, Computers for Control
Abstract: There are many software tools available for students to implement PID control laws, but these software tools are not all equally flexible, easy to use, accessible and hence effective. This paper gives a brief review of three tools: (i) author built tools in MATLAB; (ii) TSC software and (iii) PISIM software. The evaluation considers aspects such as convenience and cost for the academic as well as accessibility and useability for the students. The main results in the paper are written in such a way as to assist staff in deciding in what software its worth investing time and effort developing resources and student activities.

Keywords: Control Education, Computer and Telematics
Abstract: Many computer engineers either do not receive any control education, or are led to think that studying control is necessary only for those who want to specialise in embedded systems, real-time, and so forth. This causes a cultural gap that can have highly undesired consequences, since control-based techniques are gaining importance as a means to manage and optimise computing systems. Given the conflicts for time and space that are typical of articulated curricula like computer engineering, however, a full course on the principles of systems and control, tailored to computer engineering, is quite often an infeasible solution. This paper presents an alternative - or maybe better, a workaround - based on a suitably tailored PID-centred activity, where the occasion is taken to introduce and stress selected general ideas.

Keywords: Control Education, Control Design, Linear Control Systems
Abstract: Frequency domain is one of the most popular and powerful framework to design control system. Usually this procedure is done using the open-loop transfer function. In this work, it is explored the possibility to perform the controller design by closed-loop shaping. It is analyzed how graphical representation and interactivity can be used in this framework to help automatic control students during the learning process.

Keywords: Intelligent Autonomous Vehicles, Control Education, Mechatronic Systems
Abstract: Teaching theoretical concepts of a real-time autonomous robot system may be a challenging task without real hardware support. The paper discusses the application of the Lego Robot for teaching multi interdisciplinary subjects to Mechatronics students. A real-time mobile robot system with perception using sensors, path planning algorithm, PID controller is used as the case to demonstrate the teaching methodology. The novelties are introduced compared to classical robotic classes: (i) the adoption of a project-based learning approach as teaching methodology; (ii) an effective real-time autonomous navigation approach for the mobile robot. However, the extendibility and applicability of the presented approach are not limited to only the educational purpose.

Keywords: Control Design, Linear Control Systems, Mechatronic Systems
Abstract: In the literature, finding all stabilizing controllers are widely studied. In this paper, a case study of inverted pendulum is considered to test the methods for finding stabilizing state feedback controller. First, good set of state feedback gain matrix is calculated, two of feedback parameters are fixed to reduce the computational cost. The other two of feedback parameters that make the system stable are then calculated by gridding. The boundary of the stability region is calculated with the frequency method. In order to have fast response, the eigenvalue region of the closed loop system is defined as the left hand side of the -1+jomega line and the stability region for feedback gains are calculated for this scenario.

Keywords: Control Design, Mechatronic Systems
Abstract: Generalization of PID controllers depending on the plant relative degree is addressed in the paper. The consecutive compensator approach is redesigned in the state-space representation and augmented with the integral loop and anti-windup scheme. The stability of the closed-loop system is proved. Efficiency of the proposed approach is illustrated by the experiments carried out using the 2-DOF indoor quadcopter testbed.

Keywords: Control Design, Modelling, Identification and Signal Processing
Abstract: Recent development and implementation on intelligent control system has lead to the development of virtual sensing system technology. Virtual sensing system allows immeasureable state variables to be accurately predicted, which is very beneficial to reduce the amount of sensors required to monitor and control a system, especially for the case of controlling a quadrator. This paper proposes a novel technique to design a PID control using virtual sensing system, consisting of Diagonal Recurrent Neural Network (DRNN) and Extended Kalman Filter (EKF), which predicts the immeasureable states of the quadrator system based on the current states and control inputs. A bio-inspired optimization technique, Particle Swarm Optimization (PSO), is proposed to be applied in DRNN to avoid any possibilities from local extreme condition. Further, a PSO based PID position controller is also developed to be integrated with the designed virtual sensing system to control a quadrator.

Keywords: Automotive Control, Optimal Control, Linear Control Systems
Abstract: This paper presents the control design of a nonholonomic mobile robot with differential drive using control strategies on a linearized space state error model. In this case, a diagonal multi-variable model is obtained for which a decentralized PI controller may be designed. In this paper, PI tuning is performed through a LQR problem whose feedback gains are set as the proportional gain of the PI controller. The use of an Inertial Measuring Unit (IMU) allows for a precise posture feedback by using a Kalman Filter on the output of the sensors. For such purpose, a Sensor Fusion technique is also needed in order to combine multiple sensor output so that physical limitations of each sensor may be compensated.

Keywords: Mechatronic Systems
Abstract: This paper presents four design methods for the speed control of a mechatronics application characterized by variable parameters: variable reference, variable load disturbance and variable moment of inertia. The variations of the operating conditions and also the variations of the process parameters require the development of advanced control solutions. In this context the development of advanced control solutions will be influenced and justified significantly by the knowledge of a detailed mathematical model of the process and its parameters. In order to obtain high performance speed control for the electric drive system, referred to as the strip winding system, four proportional-integral (PI) gainscheduling control solutions are developed and tested: (1) a PI Switching-I Gain-Scheduling version with bump-less switching between three control algorithms (PI-SIGS), (2) a PI Switching-II Gain-Scheduling version with a switching logic based on Euclidean distance metric (PI-SIIGS); (3) a PI Gain-Scheduling version with a switching logic based on a generalization of the monovariable case of the Lagrange interpolating parameter value method (PI-LGS), and (4) a PI Gain-Scheduling version with a switching logic based on a Cauchy kernel distance metric (PI-CGS). The continuous-time speed controllers are tuned by the Modulus Optimum method (MO-m) and are discretized using Tustin’s method. The proposed and developed control solutions were embedded in a conventional control structure (CCS) which involves the switching between different digital control algorithms and are validated by means of simulation results. The strip winding system is discussed in this paper due to its applicability as a controlled plant in the field of mechatronics systems.

Keywords: Control Design, Chemical Process Control
Abstract: This paper presents a multivariable TITO (two inputs two ouputs) controller aimed to improve the start-up procedure of a Solar Membrane Distillation (SMD) facility, located at Plataforma Solar de Almeria (PSA). The control structure includes PID controllers and decouplers, as well as a reference governor based on a real time optimizer. The filtered Smith Predictor (SP) control structure has been used for controlling one of the output variables, whereas a cascade control scheme is employed to control the other one. The proposed approach has been tested in simulation on a nonlinear model of the SMD facility, showing promising results.

Keywords: Control Design, Large Scale Complex Systems, Optimal Control
Abstract: In this paper, a particle swarm optimization called multi-objective particle swarm optimization (MOPSO) with an accelerated update methodology is employed to tune Proportional Integral Derivative (PID) controller for a light control system. Nowadays, the demand of energy has exponentially increased and therefore is necessary to use the electric energy efficiently. Here, we tackle the use of light in offices where it is preferable to provide uniform illumination over the entire workplace by combining both natural and artificial lighting. The focus of this research is to regulate the light amount in a room at a constant level, irrespective of the disturbances from outside such as weather conditions. Thus, a control system for closed-loop regulation of the light amount in building rooms is designed. The main benefits would be a higher level of comfort and a continuous saving of energy. The obtained results verify that the MOPSO is able to perform appropriately in complex systems such as light control environment

Keywords: Linear Control Systems, Control Design
Abstract: This paper presents a new operating type of a three phase photovoltaic PID current control system connected to the low voltage distribution grid. This operating type introduces a 120-degree bus clamp PWM control method (120° BC-PWM). A 120° BC-PWM is a special switching sequences technique employing bus clamp sequences that use only one phase under a PWM and PID control state every 60° while the other phases are being clamped. The BC-PWM method was used to generate six PWM signals to control a three phase inverter system every 60° with constant power input and a small dc link film capacitor. The main objective of this paper is to use new PWM techniques with a PID current control method to reduce the switching losses of three phase inverters. The losses were reduced to 1/3th for each transistor by reducing the time operation for each transistor. The simulation results of the BC-PWM method show an improvement in the performance of the three phase inverter system connected to the grid. Simulation setup of the system obtained is built by using a SiC MOSFET, 5 kVA, 400 V line-line and 25 kHz switching frequency. The PID control is not continuously active for each phase but is operational in 60° and saturated at 120° in a half period. Following a proper tuning of the windup, it recovers very easily.

Keywords: Adaptive and Learning Systems, Control Design, Automotive Control
Abstract: A new design method that satisfies the setting settling time with small maximum overshoot in a servo controller was developed using a PI controller and an internal feedback system. The internal feedback system consists of the model parameter of the controlled object that was approximated as a second-order lag-time system. Therefore, an adaptive ability that counteracts the changing model parameters was required. In this paper, the variable parameters of the controlled object were obtained by on-line execution of a non-linear least-squares method. Suitable adaptation by the developed method was confirmed in simulation and experimental tests.

Keywords: Linear Control Systems, Control Design
Abstract: This paper deals with the design of Proportional-Integral (PI) and Proportional-Integral-Derivative (PID) controllers. The main result is a constructive determination of the set S_gamma of stabilizing PI and PID controllers achieving an H_infty norm bound of gamma on the error transfer function. This result utilizes the computation of the complete stabilizing set S recently obtained. We also point out connections between this H_infty design and Gain and Phase Margin designs. Illustrative examples are presented.

Keywords: Linear Control Systems, Control Design
Abstract: This paper presents the modification of the well-known pole placement method for first-order systems and PI control for the tracking problem. The main drawback of the original method is the presence of a zero in the closed-loop transfer function, which has a negative influence in the desired closed-loop response. Typically, this effect is cancelled by using a reference filter within a two-degree-of-freedom control scheme. However, in this work we present a simple modification of the original method that allows us to consider the zero effect in advance. First, the effect of a zero term in the response of second-order systems is analyzed to see how the time response parameters (overshoot, peak time, rise time and settling time) are affected. Afterwards, this analysis and the resulting equations are combined with the pole placement method to propose the new solution. Finally, simulation results are presented to demonstrate the advantages of the proposed method, where it is shown that faster responses than by using a reference filter are obtained.

Keywords: Control Design, Linear Control Systems, Chemical Process Control
Abstract: Virtual Reference Feedback Tuning (VRFT) and Fictitious Reference Iterative Tuning (FRIT) are the data-oriented tuning schemes for directly designing feedback controllers. In these schemes, controller parameters are tuned to achieve the desired response without any system identifications. Furthermore, these schemes have been extended to the two-degree of freedom (2DOF) control systems in recent years. The conventional design schemes of 2DOF controllers are a two-step tuning method. The first step is to design a feedback controller to satisfy the desired disturbance response. The second step is to tune the feed-forward controller parameters to achieve the desired reference response. Consider these methods are complicated, this paper provides a one-step tuning scheme for a 2DOF control system based on data-oriented method. According to the proposed scheme, the reference of the complementary sensitivity function is introduced, and the least squares method can be applied to calculate the optimal controller parameters. Finally, the effectiveness of the proposed scheme is verified by using a numerical example.

Keywords: Control Design, Computers for Control, Linear Control Systems
Abstract: Half-cycle Posicast Control is currently used in a vast range of applications. Although the proved benefits of this technique, one of its major disadvantages concerns model uncertainties. This has motivated the development and integration of robust methods to overcome this issue. In this paper, a practical experiment for auto-tuning of a two degrees of freedom control configuration using a Half-Cycle Posicast pre-filter (or input-shaping), and a PID controller under parametric variations is presented. The proposed method requires using an oscillatory system model in an auto-tuning control structure. The error derivative among the model and system output is used to trigger both the identifictation and retuning procedure. The proposed method is flexible for choosing identification plus optimization methods. Practical results obtained for electronic filter plants suggest improved performance for the considered cases.

Keywords: Control Design, Linear Control Systems, Adaptive and Learning Systems
Abstract: This study proposes a self-tuning PID controller design method based on a Kalman filter. Recently, data-driven controller tuning methods that can directly tune control parameters by closed-loop data without system models have been received much attention as convenient tuning approaches. On the other hand, in parameter estimation problems, the Kalman filter that can obtain high-precision estimation results has been applied in many research/industrial area. In this paper, a data-driven PID parameters tuning problem that is derived based on a PID control law is resolved as a Kalman filtering problem, and a self-tuning PID controller based on the Kalman filter is proposed. The effectiveness of the proposed method is evaluated by simulation and experimental examples.

Keywords: Control Design, Linear Control Systems, Modelling, Identification and Signal Processing
Abstract: This work deals with the stabilization problem of a particular class of high-order unstable linear systems with time delay. In particular, systems with one unstable pole, q-1 complex conjugate stable poles and one minimum phase zero. To solve this problem a modified version for the traditional PI controller, called in this work the Proporcional Integral Filtered PIf, is proposed. This new scheme includes a low-pass first order filter and allows improving the existing results on controlling high-order systems with time delay. Necessary and sufficient conditions for the existence of the PIf controller are expressed in terms of the parameters of the system and the maximum allowable time-delay magnitude. The proposed control scheme is illustrated by a numerical example applied to the temperature control of an unstable Continuously Stirred Tank Reactor (CSTR) linear model focused on the production of propylene glycol.

Keywords: Control Design, Linear Control Systems, Computers for Control
Abstract: This paper considers the problem of stabilization and control of linear time invariant high order systems with one or two unstable real poles, n real stable poles plus time-delay. In order to ensure a stable behavior of the closed loop system, necessary and sufficient conditions for the existence of an observer based controller together with a PI compensator are shown explicitly. Numerical simulation on academic examples are provided to illustrate the effectiveness of the proposed control strategy

Keywords: Manufacturing Plant Control, Linear Control Systems, Networked Systems
Abstract: In the present work, motivated by the recent inclusion of optical variables in combustion processes, we consider the control of a reduced Hammerstein plant model over an additive white noise (AWN) channel located at the feedback path. For comparison, assuming uncertainty in the knowledge of the static nonlinearity of the Hammerstein plant model, we first propose in a one degree-of-freedom (DOF) scheme, the design of a proportional controller for robust stability. We then introduce a PI controller, in a 3 DOF scheme, to achieve not only robust stability, but also AWN channel Signal-to-Noise Ratio (SNR) minimization and setpoint first moment tracking.

Keywords: Control Design, Chemical Process Control, Linear Control Systems
Abstract: This document addresses the problem of controlling a one-stage refrigeration cycle by using the opening of the expansion valve and the compressor speed as control variables, while the outlet temperature of evaporator secondary ux and the superheating degree of refrigerant at evaporator outlet are the controlled variables. An uncertain matrix function is obtained in order to represent the full operating range of the nonlinear system. Thus, the control decentralized approach control consists of designing Generalized- Proportional-Integral (GPI) observers for the internal loops of each controlled variable while PID controllers are tuned based on the Quantitative Feedback Theory for the respective external loops. Simulations results show that the robust controllers reacts quickly reference settings, despite the non-measurement of the disturbance variables and the dynamic coupling of the multi-variable system, compared to decentralised single PIDs proposed with the benchmark.

Keywords: Chemical Process Control
Abstract: In this paper, a PID based hierarchical control structure is proposed to improve the overall WWTP performance. The control problem is focused on the definition of integral efficiency indices for a typical WWTP operation. The efficiency index considered in this work is the ratio between the nitrogen removed in the activated sludge process (Kgr N) and the energy (kWh) required for eliminating that amount of nitrogenated compounds (N/E index). The efficiency index is used as the controlled variable for an upper level PI controller that manipulates the dissolved oxygen (DO) set point to keep the index as close as possible to a desired level. Effect of DO manipulation is analyzed and DO operation is defined in terms of its overall effect instead of local DO dynamics.

Keywords: Control Education
Abstract: This paper presents the methodology followed to evaluate students’ ability to face the challenge of controlling a refrigeration system based on vapour compression proposed as a benchmark for PID control design in the PID18 Conference. This benchmark has been also proposed as test-bed plant for the design of controllers in the subject “Industrial Control Techniques” at the University of Almería, Spain. The solutions proposed by the students range from simple SISO PID control loops (including anti-windup effect) to MIMO ones, including decoupling, filters and feedforward action to reject disturbances. All these solutions rely on models obtained from the reaction curve method. The selection of adequate specifications is encouraged, although students’ creativity has led them to exploit very aggressive specifications taking into account the different system restrictions, and obtaining very good values of the proposed evaluation indexes.

Keywords: Control Design, Distributed Parameter Systems, Large Scale Complex Systems
Abstract: During the voyage of the ship, disturbances from the sea dynamics are frequently changing, and the ship’s operation mode is also varied. Hence, it is necessary to have a good controller for steam/water loop, as the control task is becoming more challenging in large scale ships. In this paper, a robust proportional-integral-derivative (PID) autotuning method is presented and applied to the steam/water loop based on single sine tests for every sub-loop in the steam/water loop. The controller is obtained during which the user-defined robustness margins are guaranteed. Its performance is compared against other PID autotuners, and results indicate its superiority.

Keywords: Control Design, Non Linear Control Systems
Abstract: A new identification procedure for autotuning of PI controllers has been developed based on the information obtained from the oscillations that a non-linear element as a simple relay introduces in the feedback loop. Features of the method are: (1) the procedure does not demand a priori process information, (b) non-iterative algorithms are needed to derive the process parameters, (c) only one test is needed, and (d) it allows identifying the process at a user-specified phase lag in the third quadrant. The method is presented for estimation of most common transfer functions used for tuning of PI controllers: integrators, first-, second- as well as processes with non-minimum-phase dynamics.

Keywords: Non Linear Control Systems, Control Design
Abstract: This paper deals with non-smooth feedback stabilisation in presence of stochastic unbounded(normally distributed) noise. The integral term of classical proportional-integral controller is replaced by a discontinuous integrator. The overall control effort is still continuous. The behaviour of the proposed scheme under stochastic perturbations is presented. We have given a sound and non-trivial Lyapunov analysis of the closed loop system controlled by the proposed controller on stochastic dynamics.

Keywords: Adaptive and Learning Systems, Control Design, Non Linear Control Systems
Abstract: This paper proposes a PID-multi-model adaptive control (PID-MMAC) algorithm using an approximate H-infinity metric that represents the frequency loop-shaping (FLS) cost objective. Existing MMAC algorithms use L₂ or least squares-based cost functionals on a suitable error signal to perform controller switching, but their strong dependency on the properties of the excitation makes them sensitive to noise, disturbances and modeling errors. Alternatively, a system-norm-based cost function is advantageous for MMAC as it is less sensitive to the specific signals used for adaptation. In this paper, the H-infinity norm in the FLS cost objective is approximated by frequency decomposition of the real-time signals using filter-banks. An MMAC algorithm using this metric is presented and its application to controller switching is discussed. The buck converter serves as the motivating application where the adaptation seeks to compensate for degradation in its components (inductors and capacitors). A comparative study is conducted of the proposed algorithm and an L₂-based MMAC algorithm under various excitation conditions. The results show that the proposed algorithm is less susceptible to the properties of the excitation signals as compared to the least squares-based MMAC.

Keywords: Non Linear Control Systems, Large Scale Complex Systems, Control Design
Abstract: This paper proposes a PID (proportional-integral-derivative) control design method to solve the regulation problem for a class of coupled multi-agent nonlinear uncertain stochastic systems, where each agent only has access to its own regulation error without communicating with others. A three-dimensional manifold will be constructed based on the information about the Lipschitz constants of both the unknown nonlinear drift and diffusion terms, such that the three parameters of each agent's PID controller can be chosen arbitrarily from this common manifold. It will be shown that such an uncoupled PID design method can globally stabilize the whole nonlinear uncertain stochastic multi-agent system with the regulation error of each agent approaching to zero asymptotically.

Keywords: Chemical Process Control, Control Design, Non Linear Control Systems
Abstract: The problem of designing a proportional-integral (PI) temperature control with anti-windup (AW) scheme for an open-loop unstable chemical reactor is addressed. The aim is to improve the systematization of application-oriented designs employed in industrial practice. The combination of nonlinear dynamics and industrial control ideas yields PI control: (i) with back-calculation (BC) AW scheme, (ii) assurance of robust closed-loop operation with criterion to choose control gain and limits, and (iii) outperforms existing AW with BC plus conditional integration (CI) scheme. The proposed approach is illustrated and tested with a representative example through numerical simulations.