Keywords: Optimal Control, Automotive Control, Mechatronic Systems
Abstract: The use of active car suspensions to maximize driver comfort has been of growing interest in the last decades. Various active car suspension control technologies have been developed. In this work, an optimal control for a full-car electromechanical active suspension is presented. Therefore, a scaled-down lab setup model of this full-car active suspension is established, capable of emulating a car driving over a road surface with a much simpler approach in comparison with a classical full-car setup. A kinematic analysis is performed to assure system behaviour which matches typical full-car dynamics. A state-space model is deducted, in order to accurately simulate the behaviour of a car driving over an actual road profile, in agreement with the ISO 8608 norm. The active suspension control makes use of a Multiple-Input-Multiple-Output (MIMO) state-feedback controller with proportional and integral actions. The optimal controller tuning parameters are determined using a Genetic Algorithm, with respect to actuator constraints and without the need of any further manual fine-tuning

Keywords: Non Linear Control Systems, Control Design, Mechatronic Systems
Abstract: The report presents the results on the application of nonlinear PI and PID regulators in the position stabilization problem of the robots. As an example the position stabilization problem of a three-wheeled mobile robot with a displaced mass center is considered.

Keywords: Control Design, Chemical Process Control, Adaptive and Learning Systems
Abstract: Bioreactor imparts a significant role in the manufacture of pharmaceuticals, enzymes, food products, etc. as these processes depend on the bio transformation catalyzed by microorganisms. Dissolved Oxygen (DO) is one of the significant parameter in an aerobic fermentation process. DO control is difficult to achieve due to the variations in process dynamics during batch/fed-batch processes and the complex nonlinear behavior of the Bioreactor. In this paper, design and implementation of Model Reference Adaptive Control (MRAC) scheme based on MIT rule is applied to DO control of the bioreactor using the stirrer speed as control signal. A PC-supported, fully automated, multi-task control system has been designed and built by the authors using Lab VIEW .A comparative study is carried out for the experimental bioreactor with conventional PI controller and proposed MRAC scheme for DO control. Results show that MRAC controller provides good tracking performance in comparison to PI controller.

Keywords: Linear Control Systems, Modelling, Identification and Signal Processing, Distributed Parameter Systems
Abstract: Hydraulics, specifically the engineering related to river infrastructure, has had always to deal with issues as floods, erosion debilitating important civil infrastructure (bridges, etc.). In recent years it has been shown that there is predictive value for hydraulics in studying and analyzing these phenomena at a reduced scale. For this reason the microscale experimental canal was build at the Hydraulics Laboratory at the Universidad de Concepci'on, with a second copy for control purposes at the Control Systems Laboratory (LCS). The partial differential equations that govern the process are unnecessarily complex for control purposes. Known literature offers the alternative of a third order linear system, capturing the canal standing wave with a second order system together with an integrator to account for the mass accumulation. However, such a proposal, even when slowing the control to discard the standing wave dynamics is only valid for long canals. The microscale experimental canal does not satisfies that assumption, therefore we propose and adjust a first order structure to the process, which proves adequate for any given operating point selection. Nevertheless, he main three parameters of the plant model (gain, time constant and time delay) vary with the operating point. As a preliminary control approach we consider a plant model selection for a specific operating point as the nominal plant and adjust a PI control using the reaction curve method of Ziegler-Nichols. We compare the previous PI tuning with a predictive PI lambda tuning to achieve robustness, and thus better deal (in this preliminary control approach) with the inherent variability of the plant model parameters.

Keywords: Control Design, Linear Control Systems, Modelling, Identification and Signal Processing
Abstract: The interest towards using Fractional-order (FO) PID controllers in the industry is mainly fueled by the fact that these controllers have two additional “tuning knobs” that can be used to adjust the control law in a way that would benefit the control loop. However, there are certain points that are rarely addressed in literature, namely: (1) What are the particular advantages (in concrete numbers) of FOPID controllers versus conventional, integer-order (IO) PID controllers in the light of complexities arising in the implementation of the former? (2) For real-time implementation of FOPID controllers, approximations are used that are equivalent to high order linear controllers. What, then, is the benefit of using FOPID controllers? In the present paper, we attempt to address these issues by reviewing recent literature in the field and by providing relevant analysis and recommendations.

Keywords: Control Design, Linear Control Systems
Abstract: This paper proposes fractional order autotuner controller for the benchmark refrigeration system. The method is an extension of a previously presented autotuning principle and produces a robust fractional order PI controller to gain variations. Fractional order PI controllers are generalizations of the integer order PI controllers, which have a supplementary parameter that is usually used to enhance the robustness of the closed loop system. The method is not restricted to robustness to gain variations and can be adapted to obtain robust fractional order controllers to time delay or time constant variations, for example. The autotuning method presented in this paper has several advantages such as the need for a single sine test to be applied to the process to extract the necessary information and the elimination of complex nonlinear equations in the tuning procedure for fractional order controllers. The results obtained on the benchmark system indicate the method has high potential for real-life applications.

Keywords: Control Design, Non Linear Control Systems, Manufacturing Plant Control
Abstract: Actuator rate limit deteriorates control performance, and may even lead to system instability in precision process control. In this paper, a first-order plus time-delay (FOPTD) system class with actuator rate limit is considered. The describing function (DF) of the rate limiter is derived to obtain the describing functions of the closed-loop and open-loop systems, and the onset frequency in the Nichols chart is used to analyze the rate limit effects in frequency domain. A fractional-order proportional- integral (FOPI) controller is first designed based on the flat phase constraint, crossover frequency, and phase margin specifications. Then a traditional integer order PID (IOPID) controller is designed based on the same specifications to compare with the FOPI controller in the presence of actuator rate saturation. A careful simulation study is presented to validate all the conclusions.

Keywords: Linear Control Systems, Control Design
Abstract: This paper studies the performance of discrete-time fractional order controllers. The fractional derivatives and integrals are numerically implemented by means of a generalized mean of discrete generating functions. The two additional degrees of freedom provided by the method, namely the averaging order and the weight of the generating functions, are tuned for increasing the performance of the closed-loop system. Experiments with a fractional PID controller reveal the benefits of the approach.

Keywords: Modelling and Control of Biomedical Systems
Abstract: This paper compares two strategies, namely, feedback linearization (FBL) and classical proportional-integral-derivative (PID) controller, as well as their fractional versions, for the control of a simulator of the human cardiovascular circulatory system (CVS) in the Matlab/Simulink environment. The simulator is based on a hydraulic model of the system, realizable in practice, in which muscular contraction of the left ventricle is modelled by a pump with piston (tank of variable volume depending on the position of the piston), so that a control strategy is need to control the velocity of the piston in order to emulate the behaviour of the heart. Simulations are given to demonstrate, on the one hand, that all strategies have good tracking and hemodynamic performance and, on the other, that dysfunctions in the CVS can be emulated applying an appropriate control strategy that allows tracking the desired reference waveform. The nal objective of this work is the construction of an experimental platform based on this simulator to test swimming robots of small dimensions that allows to emulate the conditions in which these robots would navigate in the human circulatory system.

Keywords: Modelling, Identification and Signal Processing, Control Design, Non Linear Control Systems
Abstract: For the purpose of improving control quality, fast response, stability and other quality indexes for parallel coupled PWM rectifiers, as well as derived from being able to determine the actual transfer function which is closer to the actual control object, the fractional-order transfer function of the three-phase PWM rectifiers. This paper used a fractional proportional Integral controller instead of a traditional PI controller. The use of the fractional-order controller object will help to design a higher precision fractional-order controller of the system. This paper analyzes the characteristics of the system, constructs the function of the fractional-order controller object, designs the two current and voltage of the fractional-order controllers, performs the simulations and related experiments. Simulation and experiment results have demonstrated that using the fractional proportional integral controller to control the system of two parallel PWM rectifiers has resulted in ideal control, clearly improved control quality.

Keywords: Modelling and Control of Biomedical Systems
Abstract: In this paper, a nonovershooting tracking controller is proposed for the continuous infusion of multiple drugs that have interactive effects. The proposed controller design method exploits the freedom of eigenstructure assignment pertinent to the design of feedback controllers for multi-input, multi-output (MIMO) systems. For drug dosing, a nonovershooting tracking controller restricts the undesirable side effects of drug overdosing. The proposed tracking controller is based on an estimate of the full state using a hybrid extended Kalman filter (EKF) that is used to reconstruct the system states from the measurable system outputs. An integral control action is included in the controller design to achieve robust tracking in the presence of patient parameter uncertainty. Simulation results and performance analysis of the proposed control strategy are also presented using 20 simulated patients.

Keywords: Modelling and Control of Biomedical Systems, Control Design
Abstract: In this paper we propose a PID-based control scheme for the automatic regulation of the neuromuscular blockade level during surgery. In particular, we introduce an optimized tuning of the PID controller parameters based on a standard set of patient models presented in literature. The tuning procedure is based on the solution of a min-max multiobjective optimization problem that takes into account the control performance, the control effort and the robustness. A genetic algorithm is used to solve the optimization problem and to find the optimal tuning. Then, in order to evaluate the control systems robustness, the optimal PID controller is tested in simulation on a database of patient models estimated from real data. The obtained results demonstrate that the performance achieved by considering an optimized PID tuning satises the clinical specications and is robust to the inter-patient variability.

Keywords: Modelling and Control of Biomedical Systems
Abstract: In this work, a Proportional-Integral-Derivative (PID) controller based two-degree-of-freedom control scheme for Depth of Hypnosis (DoH) in general anesthesia is proposed. This approach uses the Bispectral Index Scale (BIS) as a controlled variable and propofol administration as a control variable. The developed structure applies a new compensation scheme, which reduces the influence of the nonlinear element. In this context, we exploit the linear part of the patient model, that can be obtained from the demographics of each individual patient. The parameters are tuned using the optimization procedure based on a genetic algorithm. The evaluation of the proposed technique is performed using intra-patient variability with a Monte Carlo method. Additionally, the performance of the analyzed system has been verified using several indexes. The simulation results show that desired characteristics are obtained for both induction and maintenance phases.

Keywords: Modelling and Control of Biomedical Systems
Abstract: Control of propofol anesthesia is characterized by large variability in individual responses to drug infusion, relatively simple system dynamics and relatively low performance criteria. Robust PID control can be expected to provide adequate control given these characteristics. While feasibility of robust PID control of propofol anesthesia has been shown in clinical trials, higher-order controllers that use an explicit model might provide additional valuable characteristics. This paper examines the performance achieved with a manually tuned robust PID controller and a higher-order Q-design controller. The additional degrees of freedom in the Q-design allow an increase in the robustness margin, at the cost of decreased gain at low frequencies and corresponding increased time to induction of anesthesia. These results indicate that the uncertainty introduced by interpatient variability is an important factor limiting closed-loop performance. Performance improvement from increased controller complexity may therefore be limited, unless strategies aimed at reducing the uncertainty are implemented.

Keywords: Modelling and Control of Biomedical Systems, Modelling, Identification and Signal Processing, Control Design
Abstract: The closed loop regulation of hypnosis implies the mixed effect of the actions dictated by a software based controller, and by the expert knowledge of the anesthesiologist. Other effects such as slew rate limitations due to resolution limits or saturation of the pump infusion system are also present in practice. Almost without exception, the actions of the anesthesiologist and other hardware limitations are not taken into account by the software based controller, hence they are regarded as disturbances. In this work, a PID controller is implemented to investigate the effects of such additional features in the closed loop dynamics. The results are discussed based on simulation study on a linear patient dynamic model.

Keywords: Modelling and Control of Biomedical Systems
Abstract: In this paper a new simplied control scheme for the neuromuscular blockade level that only requires the knowledge of one model parameter is proposed. The control law is designed to track a desired target neuromuscular blockade level. Furthermore, the performance of this approach is compared with the results of a PI controller. The results were validated by simulations based on real data collected during surgeries.

Keywords: Control Design, Linear Control Systems, Mechatronic Systems
Abstract: This work shows that a Proportional Derivative controller with weighted Derivative action plus a Disturbance Observer, is equivalent to a Proportional Integral Derivative (PID) controller with weighted Proportional and Derivative actions, when they are applied to servo drives. A byproduct of this equivalence is a tuning rule for the PID controller, called the DOB tuning, which is expressed in terms of the cutoff frequency of the filter employed in the DOB. Experiments in a laboratory testbed allow assessing the performance of a PID controller under the resulting tuning formulae.

Keywords: Mechatronic Systems, Control Design, Linear Control Systems
Abstract: The control of slip in a belt Continuously Variable Transmission (CVT) has been the subject of many research papers. Optimal control of the belt CVT is of major importance for the efficiency as demonstrated in literature. The challenge in optimizing that efficiency is in the reduction of the necessary clamping forces while the stability of the variable transmission is maintained. Although these problems have already been tackled to a certain extent, mostly fairly complex controllers are proposed. The goal of this paper is to propose a straightforward though effective method to control slip. The main idea of the paper is to use linearized equations of the slip dynamics to update the controller parameters in function of the operating point. This approach allows to reduce the highly nonlinear system to a first order transfer function which is easily controlled with a PI controller. Results based on extensive simulations show that the controller is robust against torque disturbances and speed ratio variations.

Keywords: Control Design, Linear Control Systems, Mechatronic Systems
Abstract: Stepping motors are used in numerous applications because of their low manufacturing cost and simple open-loop position control capabilities. The bulk of the widely used full-step open-loop stepping motor drive algorithms are driven at maximum current to avoid step loss. This non-optimal way of control leads to low eciency. In order to use stepping motors in a more optimal way, closed-loop control is needed. A previously described sensorless load angle estimation algorithm, solely based on voltage and current measurements, is used to provide the necessary feedback without using a mechanical position sensor. In this paper, an adaptive PI controller which optimizes the current level based on the feedback of the estimated load angle is introduced. Although the current - load angle dynamics are highly non-linear, an adaptive PI controller with the settling time of the current reduction as design constraint is worth considering. Especially because few tuning parameters are required. The described method is complimentary to the popular methodology used to drive a stepper motor, which is based on step command pulses. Measurements validate the proposed approach.

Keywords: Mechatronic Systems, Linear Control Systems, Control Design
Abstract: The quadcopter is one of the most popular unmanned aerial vehicles in both military and commercial in- and outdoor applications. In this study, the problem of UAV attitude control is investigated when there are discrepancies in the characteristics of the 4 actuators, i.e., electrical motors and propellers. To tackle this problem in a simple way, a cascade control strategy is proposed with a PD controller in the inner loop to achieve stabilization, and PI controller in the outer loop to ensure disturbance rejection. This way, the external disturbance created by the actuator asymmetry is compensated by the PI loop. The robustness of the control strategy is tested in simulation as well as in real-life tests.

Keywords: Modelling, Identification and Signal Processing, Control Design
Abstract: Main idea of this paper is the development of Hardware-in-the-Loop test platform in order to flight mechanical modeling and better stabilization of multirotor vehicles via different feedback control structures, including PID controllers. First, nonlinear mathematical model of the quadrotor platform is built and validated via Matlab/Simulink based simulation environment.Then, Hardware-in-the-Loop (HIL) test scenario is developed to analyze and tune controller parameters with the help of in-house designed testbed mechanism. Next step is observing the quadrotor attitude maneuvers via embedded hardware over the gyroscopic gimballed testbed. The HIL testbed enables us validate and calibrate model and control parameters within real-time environment including inertial and mechanical sensors for multirotor systems. In this study, the particular platform is IRIS cross-type quadrotor vehicle PID based controlled for stable hover flight.

Keywords: Control Design
Abstract: Existing tuning formulas for PID based on relay feedback experiments are derived from continuous-time systems theory, even though most such systems are implemented digitally. These formulas rely on the fact that, according to this continuous time theory, the relay feedback experiment allows the identification of the ultimate point of the plant's frequency response - the point at which its Nyquist plot crosses the negative real axis. We have shown in a recent paper that a sampled relay feedback experiment may exhibit various limit-cycles at possibly quite different frequencies, even for quite reasonable sampling rates - that is, well within the ranges recommended by sampling theory and control textbooks. In this paper we show the deleterious effect of this reality on the tuning of PID controllers and propose an improvement to the tuning formulas to overcome this limitation.

Keywords: Control Design, Linear Control Systems
Abstract: In this article, a method to tune proportional-integral-derivative controllers for the class of plants with relative degree one is proposed, since this class includes plants that are not amenable to application of the traditional Ziegler-Nichols (ZN)-like methods. The method presented here is based on a modified relay feedback experiment with inclusion in the loop of a transfer function of constant phase in a defined range of frequencies. Thus, with a single experiment and simple tuning formulas this method enlarges the class for which the ZN-like methods can be applied.

Keywords: Control Design, Linear Control Systems
Abstract: This paper addresses the important and well studied problem of synthesising PID controllers for load disturbance rejection. The tuning rationale, on which some general words are spent in connection to literature research, is to shape the disturbance-to-output frequency response, together with conveniently assigning the poles of the corresponding transfer function. Analytical tuning formulae are derived, to maximise simplicity and make the presented method applicable on any device. Simulation results support the proposal.

Keywords: Control Design, Linear Control Systems, Manufacturing Plant Control
Abstract: This paper presents a new model-free tuning approach for the PID controller tuning with the employment of the refined recursive instrumental variable (RIV) method. The proposed approach can be applied to solve the control loop tuning problem without identification of the plant or process model and it can be implemented in the online manner. Also, the colored measurement noise has been taken into account. For PI and PID control, the implementation details and the step by step procedures are provided respectively. Two simulation examples are provided to validate the effectiveness of the proposed approach.

Keywords: Control Design, Linear Control Systems, Chemical Process Control
Abstract: This paper is about a performance assessment strategy for IMC PI control systems using collected data from a specific closed-loop experiment. It is used time and frequency indexes to analyze how close or far the closed-loop is from the desired performance. A data-driven PI retuning method is applied to improve the control system for IMC PI specifications and the chosen indexes.

Keywords: Control Design, Linear Control Systems, Computers for Control
Abstract: This paper analyzed and designed a new Repetitive Current Controller (New RCC), performing a comparison with a traditional RCC. Based on the tracking performance by the original PI controller, the New RCC uses another PI controller to replace the compensator to achieve better control performance. That is the novel approach of the proposed method. And it has been proved in this paper that the controller is not sensitive to the controlled object, therefore it is suitable for use in complex object model scenarios. Simulations and experimental results demonstrate that the new RCC is effective in improving the AC current quality of the three-phase PWM rectifier, which is the right method of control, with high practical application value.

Keywords: Control Design, Non Linear Control Systems
Abstract: Aircraft antiskid braking system is designed to prevent the main wheels from locking and additionally seeking the optimal braking performance. Wheel deceleration is the traditional controlled target used in antiskid system, since it can be easily measured by angular velocity transducer. However the optimal target value is hard to find due to the changing of road-surface and aircraft velocity. An alternative controlled target is the wheel longitudinal slip which is more robustly controllable under all conditions. But the wheel slip cannot be measured directly, that will definitely result in control error from the poor estimated aircraft speed. In this work a PID control scheme based on mixed slip-deceleration input variable is proposed for aircraft antiskid braking system. This control algorithm is able to stabilize the wheel slip around any equilibrium point. Moreover, it inherits all the appealing characteristics of slip control, while overcoming its sensitivity to slip measurement errors.

Keywords: Control Design, Mining, Mineral and Metal Processing, Control Education
Abstract: In this paper, we studied the bottom hole pressure (BHP) control in an oil well during drilling. Today marginal wells with narrow pressure windows are frequently being drilled. This requires accurate and precise control to balance the bottom hole pressure between the pore and fracture pressure of the reservoir. This paper presents three control schemes to stabilize the BHP profile, including proportional-integral(PI) control, PI with feed-forward control and adaptive PI with feed-forward control. The proposed schemes are carried out through simulations on a high-fidelity hydraulic drilling simulator for flow rate changes and BHP set-point changes. The simulation results illustrate the effectiveness of proposed control schemes.

Keywords: Control Design, Automotive Control
Abstract: This paper proposes a new approach to find operating points for gain scheduling control using PID controllers. The operating point are computed with a frequency analysis of the system that gives the number of operating points needed and their values. The PID are weighted in their operating area using continuous functions that depend on the scheduling parameter. A concrete example of an autonomous vehicle lateral guidance shows the effectiveness of the method comparing different configuration of operating points and weights.