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

Neuromyelitis optica spectrum disorder: a case Report from Rehman Medical institute, Peshawar.

Devic\u27s disease or Neuromyelitis Optica is a serious, rare idiopathic neurological disorder which affects the optic nerve and the spinal cord. A 15-year-old girl was admitted in the neurology was with a previous history of 4 episodes of weakness in both the lower limbs and urinary retention. The patient gradually lost her eyesight in both eyes at the age of 8. Initially, she was diagnosed as a case of Multiple Sclerosis at the age of 11 when she presented with first episode of lower limb weakness. Later, Seropositivity for Aquaporin 4 IgG and clear MRI scan of the brain confirmed the diagnosis of Neuromyelitis Optica

Evaluation of the in vitro antioxidant and antitumor activity of hydroalcoholic extract from Jatropha mollissima leaves in Wistar rats

Introduction: Despite modern sciences and advancements in new drugs or chemicals, the new era now rushes natural remedies for various illnesses and diseases that lead to end organ damage. In this study, we investigated Jatropha mollissima ethanolic extract’s effect against doxorubicin-induced cardiotoxicity and renal toxicity.Methods: To determine phytochemicals, a phytochemical screening was conducted. Various assays were used to measure the antioxidant activity, including the DPPH (2,2-diphenylpicrylhydrazyl), SOD (superoxide dismutase), NO (nitric oxide), and others. The antiproliferative effect of Jm was assessed by MTT assay; morphological analysis was performed using an inverted and phase contrast microscope, ultra morphological analysis of apoptosis with acridine orange (AO)/propidium iodide (PI) staining.Results: It was seen that doxorubicin caused elevated serum markers and abnormal changes in histological patterns. The significant reduction in cardiac and renal marker levels seen in groups given either 400 or 600 mg/kg of crude extract demonstrates that Jm has a protective effect against doxorubicin-induced cardiotoxicity due to the presence of active phytoconstituents having antioxidant potential. There is a dose-dependent decrease in cell viability when using J. mollissima. Apoptosis was observed in the treated cells.Conclusion: In conclusion, our research lends credence to the idea that J. mollissima could be used for cancer management and have cardioprotective and nephroprotective effects

Corporate governance characteristics and valuation: inferences from quantile regression

Prior literature on corporate governance and performance provides mixed evidence on the impact ofvarious corporate governance measures on performance indicators. However, most of literatures adoptthe Ordinary Least Square (OLS). This method is based on the central tendency, which may not appro-priately represent the reality in cases where the dependent variable ranges between upper and lowervalues and hence the relationship may not be homogenous across different percentiles of the dependentvariables. A variable having a positive impact based on the central tendency for firms may not be the casefor the firms in the upper or lower bounds. Thus, estimating the means using OLS may not reflect andrepresent the heterogeneity in the estimated relationship. Therefore, quantile regression estimates therelationship at any point conditional on the distribution of dependent variable. This would enable us togenerate various estimated coefficient at certain quantile of dependent variable. Therefore, the objectiveof the study is twofold. First, this study aims to investigate the relationship between corporate gover-nance and performance using OLS. Second, this work further explores the impact of corporate governancemechanisms on performance using quantile regression so as to compare and to shed light on whetherthere is heterogeneity in the influence of these variables on the performance of listed companies acrossquantiles. The results of the study provide evidence that quantile approach shows inconsistency in theresult with OLS and hence indicating the impact depends on the scale size. This theoretically providesfurther support that OLS may represent a poor estimation approach for the reality of firms.La literatura previa sobre gobierno corporativo y desempe ̃no aporta una evidencia mixta del impactode las diversas mediciones del mismo sobre los indicadores del desempe ̃no. Sin embargo, gran parte dela literatura adopta el método de los mínimos cuadrados ordinarios (MCO). Dicho método se basa en latendencia central, que puede no constituir una representación adecuada de la realidad en aquellos casosen los que la variable dependiente oscila entre los valores superior e inferior y, por tanto, la relaciónpuede no ser homogénea a lo largo de los diferentes percentiles de las variables dependientes. Unavariable que tenga un impacto positivo basado en la tendencia central para las empresas puede no serel caso para aquellas posicionadas en los límites superior o inferior. Entonces, el cálculo de las mediascon el uso del método MCO no reflejaría ni representaría la heterogeneidad en la relación estimada. Porello, la regresión de cuantiles calcula la relación en cualquier punto, supeditado a la distribución de la variable dependiente. Esto nos permitiría generar diversos coeficientes estimados en cualquier cuantil dela variable dependiente. En consecuencia, el objetivo de este estudio es doble: investiga la relación entre elgobierno corporativo y el desempe ̃no, utilizando el método MCO y explora el impacto de los mecanismosdel gobierno corporativo sobre el desempe ̃no, utilizando la regresión de cuantiles, a fin de comparar yarrojar luz sobre la posibilidad de que exista heterogeneidad en la influencia de dichas variables sobreel desempe ̃no de las empresas cotizadas, a lo largo de los cuantiles. Los resultados del estudio aportanevidencia acerca de que el enfoque de los cuantiles es inconsistente con el método MCO y, por tanto,indica que el impacto depende del tama ̃no de la escala. Esto respalda, además, el hecho de que el métodoMCO puede representar un enfoque de cálculo más débil para la realidad de las empresas

Cross-sectional study of knowledge of stroke Management amongst doctors of a tertiary Care Hospital; Peshawar, Pakistan

Stroke is one of the leading causes of mortality and neurological disability worldwide. ‘Time is brain’ and prompt management of stroke is vital to improve the outcomes. Knowledge of stroke management is important for clinicians working in various specialties and this study focused on evaluation of this vital aspect