Fuzzy-Immune-Regulated Adaptive Degree-of-Stability LQR for a Self-Balancing Robotic Mechanism: Design and HIL Realization

This letter formulates a fuzzy-immune adaptive system for the online adjustment of the Degree-of-Stability (DoS) of Linear-Quadratic-Regulator (LQR) procedure to strengthen the disturbance attenuation capacity of a self-balancing mechatronic system. The fuzzy-immune adaptive system uses pre-configured control input-based rules to alter the DoS parameter of LQR for dynamically relocating the closed-loop system's eigenvalues in the complex plane's left half. The corresponding changes in the eigenvalues are conveyed to the Riccati equation, which eventually yields the self-adjusting LQR gains. This arrangement allows for the flexible manipulation of the applied control effort and the response speed as the error conditions change. The efficacies of the self-tuning LQR scheme are verified by performing custom-designed hardware-in-the-loop experiments on the Quanser rotary inverted pendulum system. As compared to the DoS-LQR, the proposed controller improves the pendulum's transient recovery time, overshoots, input demands, and offsets by 32.3%, 50.5%, 33.9%, and 33.3%, respectively, under disturbances. These experimental outcomes verify that the proposed self-tuning LQR law considerably improves the system's disturbance attenuation capability

Complex-order PID controller design for enhanced blood-glucose regulation in Type-I diabetes patients

Type-I Diabetes (TID) is a chronic autoimmune disease that elevates the glucose levels in the patient’s bloodstream. This paper formulates a fractional complex-order Proportional-Integral-Derivative (PID) control strategy for robust Blood Glucose (BG) regulation in TID patients. The glucose-insulin dynamics in blood plasma are modeled via the Bergman-Minimal-Model. The proposed control procedure employs the ubiquitous fractional order PID controller as the baseline BG regulator. The design flexibility of the baseline regulator to effectively normalize the BG levels is enhanced by assigning complex orders to the integral and differential operators instead. The resulting Complex Order PID (CO-PID) regulator strengthens the controller’s robustness against abrupt variations in the patient’s BG levels caused by meal disturbances or sensor noise. The controller parameters are numerically optimized offline. The aforesaid propositions are justified by performing credible simulations in which the proposed controller is tasked to effectively track a set point value of 80 mg/dL from an initial state of hyperglycemia under various disturbance factors. As compared to the FO-PID controller, the CO-PID controller improves the reference tracking-error, transient recovery-time, and control expenditure by 13.1%, 33.4%, and 28.1%, respectively. The simulation results validate the superior reference-tracking accuracy of the proposed CO-PID controller for BG regulation

Adaptive optimal control of under-actuated robotic systems using a self-regulating nonlinear weight-adjustment scheme: Formulation and experimental verification

This paper formulates an innovative model-free self-organizing weight adaptation that strengthens the robustness of a Linear Quadratic Regulator (LQR) for inverted pendulum-like mechatronic systems against perturbations and parametric uncertainties. The proposed control procedure is devised by using an online adaptation law to dynamically adjust the state weighting factors of LQR's quadratic performance index via pre-calibrated state-error-dependent hyperbolic secant functions (HSFs). The updated state-weighting factors re-compute the optimal control problem to modify the state-compensator gains online. The novelty of the proposed article lies in adaptively adjusting the variation rates of the said HSFs via an auxiliary model-free online self-regulation law that uses dissipative and anti-dissipative terms to flexibly re-calibrate the nonlinear function's waveforms as the state errors vary. This augmentation increases the controller's design flexibility and enhances the system's disturbance rejection capacity while economizing control energy expenditure under every operating condition. The proposed self-organizing LQR is analyzed via customized hardware-in-loop (HIL) experiments conducted on the Quanser's single-link rotational inverted pendulum. As compared to the fixed-gain LQR, the proposed SR-EM-STC delivers an improvement of 52.2%, 16.4%, 55.2%, and 42.7% in the pendulum's position regulation behavior, control energy expenditure, transient recovery duration, and peak overshoot, respectively. The experimental outcomes validate the superior robustness of the proposed scheme against exogenous disturbances

Complex Fractional-Order LQIR for Inverted-Pendulum-Type Robotic Mechanisms: Design and Experimental Validation

This article presents a systematic approach to formulate and experimentally validate a novel Complex Fractional Order (CFO) Linear Quadratic Integral Regulator (LQIR) design to enhance the robustness of inverted-pendulum-type robotic mechanisms against bounded exogenous disturbances. The CFO controllers, an enhanced variant of the conventional fractional-order controllers, are realised by assigning pre-calibrated complex numbers to the order of the integral and differential operators in the control law. This arrangement significantly improves the structural flexibility of the control law, and hence, subsequently strengthens its robustness against the parametric uncertainties and nonlinear disturbances encountered by the aforementioned under-actuated system. The proposed control procedure uses the ubiquitous LQIR as the baseline controller that is augmented with CFO differential and integral operators. The fractional complex orders in LQIR are calibrated offline by minimising an objective function that aims at attenuating the position-regulation error while economising the control activity. The effectiveness of the CFO-LQIR is benchmarked against its integer and fractional-order counterparts. The ability of each controller to mitigate the disturbances in inverted-pendulum-type robotic systems is rigorously tested by conducting real-time experiments on Quanser single-link rotary pendulum system. The experimental outcomes validate the superior disturbance rejection capability of the CFO-LQIR by yielding rapid transits and strong damping against disturbances while preserving the control input economy and closed-loop stability of the system

Robust MPPT Control of Stand-Alone Photovoltaic Systems via Adaptive Self-Adjusting Fractional Order PID Controller

The Photovoltaic (PV) system is an eco-friendly renewable energy system that is integrated with a DC-DC buck-boost converter to generate electrical energy as per the variations in solar irradiance and outdoor temperature. This article proposes a novel Adaptive Fractional Order PID (A-FOPID) compensator with self-adjusting fractional orders to extract maximum power from a stand-alone PV system as ambient conditions change. The reference voltage is generated using a feed-forward neural network. The conventional FOPID compensator, which operates on the output voltage error of the interleaved buck-boost converter, is employed as the baseline maximum-power-point-tracking (MPPT) controller. The baseline controller is retrofitted with an online state-error-driven adaptation law that dynamically modifies the fractional orders of the controller’s integral and differential operators. The adaptation law is formulated as a nonlinear hyperbolic scaling function of the system’s state error and error-derivative variables. This augmentation supplements the controller’s adaptability, enabling it to manipulate flexibly the tightness of the applied control effort as the operating conditions change. The efficacy of the proposed control law is analyzed by carrying out customized simulations in the MATLAB Simulink environment. The simulation results show that the proposed MPPT control scheme yields a mean improvement of 25.4% in tracking accuracy and 11.3% in transient response speed under varying environmental conditions

A robust variable-structure LQI controller for under-Actuated systems via flexible online adaptation of performance-index weights

This article presents flexible online adaptation strategies for the performance-index weights to constitute a variable structure Linear-Quadratic-Integral (LQI) controller for an underactuated rotary pendulum system. The proposed control procedure undertakes to improve the controller s adaptability, allowing it to flexibly manipulate the control stiffness which aids in efficiently rejecting the bounded exogenous disturbances while preserving the system s closed-loop stability and economizing the overall control energy expenditure. The proposed scheme is realized by augmenting the ubiquitous LQI controller with an innovative online weight adaptation law that adaptively modulates the state-weighting factors of the internal performance index. The weight adaptation law is formulated as a pre-calibrated function of dissipative terms, anti-dissipative terms, and model-reference tracking terms to achieve the desired flexibility in the controller design. The adjusted state weighting factors are used by the Riccati equation to yield the time-varying state-compensator gains

Development of Novel Experimental Infrastructure for Collecting High-Fidelity Experimental Data for Refrigerant to Air Heat Exchangers

Manufactures of fin-and-tube heat exchangers often employ predictive modelling tools in order to reduce development cost and time. These tools require high-fidelity experimental data to validate the accuracy of their predictions. To that end, this paper presents the design and development of a custom-designed pumped refrigerant loop to collect high-fidelity experimental data for fin-and-tube heat exchangers in three operating modes: (1) single-phase refrigerant, (2) evaporator, and (3) condenser mode. It is combined with a small-scale wind tunnel installed in a psychrometric chamber facility for the purpose of validating the recently developed discretized fin-and-tube heat exchanger models (Sarfraz et al., 2019a and 2019b). The pumped refrigerant loop is able to precisely control desired refrigerant test conditions, flowrate to each individual heat exchanger circuit, and has been sized in order to test heat exchanger coils up to a capacity of 5 tons (17.5 kW). A preliminary test plan and uncertainty analysis is presented for the first heat exchanger coil to be tested. The uncertainty analysis showed that the experiment will have the capability of measuring overall coil capacity within ±2%. A design of experiments is also presented, which suggests that 9 tests per coil is an adequate number for minimizing experimental effort. A preliminary experiment was performed which showed that the average air and refrigerant side capacities match to within 1.1% of each other. This provides evidence that the experimental setup has the capability to far exceed the 5% threshold set by ASHRAE Standard 33 (2016)

Performance enhancement of multivariable model reference optimal adaptive motor speed controller using error-dependent hyperbolic gain functions

The main contribution of this paper is to formulate a robust-adaptive and stable state-space speed control strategy for DC motors. The linear-quadratic-integral (LQI) controller is utilized as the baseline controller for optimal speed-regulation, accurate reference-tracking and elimination of steady-state fluctuations in the motor’s response. To reject the influence of modelling errors, the LQI controller is augmented with a Lyapunov-based model reference adaptation system (MRAS) that adaptively modulates the controller gains while maintaining the asymptotic stability of the controller. To further enhance the system’s robustness against parametric uncertainties, the adaptation gains of MRAS online gain-adjustment law are dynamically adjusted, after every sampling interval, using smooth hyperbolic functions of motor’s speed-error. This modification significantly improves the system’s response-speed and damping against oscillations, while ensuring its stability under all operating conditions. It dynamically re-configures the control-input trajectory to enhance the system’s immunity against the detrimental effects of random faults occurring in practical motorized systems such as bounded impulsive-disturbances, modelling errors, and abrupt load–torque variations. The efficacy of the proposed control strategy is validated by conducting credible hardware-in-the-loop experiments on QNET 2.0 DC Motor Board. The experimental results successfully validate the superior tracking accuracy and disturbance-rejection capability of the proposed control strategy as compared to other controller variants benchmarked in this article

THE RANDOMIZED POTENTIAL RESEARCH OF BIS DIRECTED LOW-FLOW SEVOFLURANE ANESTHESIA; AIR HARMLESS AS COMPARED TO NITROUS OXIDE

Objective: This potential randomized BIS measured research remained led to liken little-stream anesthesia procedures through or else deprived of nitrous oxide (N2O) by means of remifentanil also sevoflurane, through deference to ventilation limitations also sevoflurane ingesting. Methodology: Fifty-one, ASA I/II women youthful than 66-year-old, reserved for gynecological medicinal technique suffering right around three hours under customary anesthesia have been chosen. Our Research was conducted at Lahore General Hospital, Lahore Pakistan at April 2016 to August 2017. Electrocardiogram (ECG), beat oximetry, non-prominent vein weight, train-of-four (TOF) and bispectrality record (BIS) had been checked. Anesthesia used to be hurried through inj propofol 3 mg/kg with expansions of 12 mg until BIS used to be underneath sixty-five and rocuronium 0.7 mg/kg. Patients have been randomized to one of 3 social affairs, 17 sufferers in each, to get either N2O (Group-N) or sans n2o anesthesia (Groups R1 nd R2). All affiliations got bolus remifentanil 0.6 μl/kg and after that blends at 0.3 μl/kg/min (Set-R I), or else 0.06 μl/kg/min (Set-R 2) as help. Anesthesia was once stayed aware of sevoflurane in O2 + N2O or air. Signs exhibiting acceptable significance of anesthesia at some point or another of preservation time of anesthesia were HR, vein blood strain and BIS. The purpose behind existing was to get a BIS charge some place in the scope of 45 and sixty-five and hemodynamic parameters inside 22% of benchmark regards. Opiate implantations were consistent as sevoflurane vaporizer dial setting was once adjusted in ± 0.6% volumes to keep up this goal. Systolic, diastolic and prescribe vein loads, HR, SpO2, the animated and passed gas deficient weight estimations of O2, sevoflurane, N2O, and CO2, BIS regards sevoflurane vaporizer dial settings, and recovery models have been recorded. Evaluating factors had been at each and every 6 min at some stage in therapeutic technique. An irrelevant impelled oxygen care (FiO2) of 0.4 used to be kept up. Usage and costs for sevoflurane have been resolved. Results: Measurement data, time of cautious movement and anesthesia were near between the social affairs. An epic decrease was once observed in FiO2 with the guide of period in altogether social affairs. For entirely annual periods FiO2 was once quantifiably extended in Set-N. The refinement between passed on O2 also FiO2 remained most negligible in Set-N. The qualification among animated and passed portions of sevoflurane (Fiserv and Festive) diminished by strategy for time in the long run of the low stream time span. It used to be lower in Group-N than in remifentanil social occasions. Complete sevoflurane use used to be noticeably higher in Group-R 2 than Group-N anyway there was at one time no sweeping complexity in sevoflurane use and charges per affected individual each minute between social affairs. Recovery events had been associated between the social occasions. Conclusions: We contemplated that danger of hypoxia and shaky pain-relieving use did never again contrast with or then again other than N2O in remifentanil-sevoflurane, low buoy anesthesia. Checking FiO2 is fundamental in both air/ O2 and N2O/O2 mixes. Both are secure to oversee with the exception of if FiO2 is lower than 35%. BIS-guided sevoflurane with its low dissolvability incorporate successfully modifies right away to variable pain-relieving significance goes over the range of low-stream anesthesia. Key words: Anesthesia, Locked Circuit, Anesthesia, Rebreathing, Nitrous oxide, Consciousness Monitors, Bispectrality Catalogue Monitor

THE DETERMINANTS OF JOB SATISFACTION IN PUBLIC SERVICE ORGANIZATION

The aim of this study is to identify the impact of demographic, working environment and managerial control determinants on job satisfaction. Job satisfaction has been a major course of study long time ago. However, in Pakistani context, little focus has been made on job satisfaction of public service employees. Pakistan is country whereby working in public service organization is deemed attractive. The organizational objective behind public owned sectors is to serve the community; hence identifying the determinants of job satisfaction of public sector officials has been the major focus of this study. Data was obtained from the employees of Karachi Water Sewerage Board through structured questionnaire. Hence, beside secondary sources of data, this paper mainly depends upon primary source of data. The study find out that 95% of variance is explained by demographic, working environment and managerial control for the level of job satisfaction among employees of Karachi Water & Sewerage Board