Robust Feedback Research Articles

Driver Safety Protocols, Emergency Response Systems, Insurance Coverage, and Customer Feedback on Service Quality in Indonesia's ride-hailing industry

This study examines the impact of driver safety protocols, emergency response systems, insurance coverage, and customer feedback on service quality in Indonesia's ride-hailing industry. Utilizing a mixed-methods approach, quantitative data were collected from 400 ride-hailing users through a structured survey, while qualitative insights were gathered from 20 semi-structured interviews with drivers, customers, and company representatives. The findings indicate that emergency response systems have the most significant positive effect on service quality, followed by customer feedback and driver safety protocols. Although insurance coverage is also important, it demonstrated a comparatively lower impact. The study highlights the need for ride-hailing companies to enhance safety measures, improve communication regarding insurance, and develop robust customer feedback mechanisms to foster trust and satisfaction. These insights provide actionable recommendations for industry stakeholders and contribute to the theoretical understanding of service quality determinants in the ride-hailing context.

Robust Bumpless Transfer Control for Switched Systems with Unmatched Uncertainties Based on the Common Robust Integral Sliding Mode Under Arbitrary Switching Rules

In this paper, a robust bumpless transfer control scheme for tracking control is proposed to avoid large jumps in the control signals for a switched system (SS) with unmatched uncertainty and disturbance. The robust bumpless controller comprises a robust linear feedback control (RLFC) and a continuous sliding mode control (CSMC) based on the given robust integral sliding mode (RISM). The RLFC meets the requirement of bumpless indices, and the CSMC suppresses the unmatched uncertainty and disturbance. First, the RLFC design is proposed, and the linear feedback coefficients satisfy the bumpless indices, despite the uncertainty and disturbance. Then, a RISM surface design is proposed, in which the uncertain SS satisfies the given H-infinity robust performance index, and can resist the unmatched uncertainty. Consequently, the CSMC ensures that the RISM surface can be reached in finite time from the initial time instant. By composing the CSMC with the RLFC, the control scheme achieves the robust trajectory tracking and the suppression of the control signal bumps during switching. Finally, the proposed robust bumpless transfer control scheme was applied to the different examples, and the simulation results verified its effectiveness.

Home Services Recommendation System using Machine Learning for Urban Areas

The Kotlin-based on-demand home service system streamlines household tasks by offering services such as repairs, cleaning, gardening, and plumbing. In today's fast-paced world, it provides quick solutions for maintaining a clean and hygienic living environment. The Housekeeper Finder app is a prominent player in this space, utilizing advanced machine learning algorithms to deliver personalized service recommendations based on user preferences. It includes essential services like cooking, laundry, and elder care, along with a robust feedback system to improve service quality. Users can easily book services from anywhere, leveraging GPS technology to connect them with nearby providers. The "Domestic Android Application for Home Services" further enhances accessibility through location-based service requests and mapping capabilities for a seamless user experience across platforms.A s cities transition into Smart Cities, integrated information systems open new avenues for urban service recommendations, fostering liveability and sustainability. Recommendation systems analyse user behaviour to provide tailored suggestions using techniques like collaborative filtering and hybrid methods. In response to the challenges of modern work culture, the e-commerce landscape now offers easy access to essential services via mobile applications, ultimately transforming how households address their needs and promoting safer, cleaner living space.

Robust Feedback Instability Analysis in the ${\mathscr {L}}_{2}$-Gap

Robust Feedback Instability Analysis in the ${\mathscr {L}}_{2}$-Gap

Adaptive robust motion control for hydraulic load sensitive systems considering displacement dynamic compensation

Hydraulic load-sensitive systems (HLSS) are widely used for high power density and energy efficiency. This study introduces an adaptive, energy-efficient HLSS with a valve-controlled variable motor. The system faces challenges from non-linearities, including internal higher-order dynamics due to displacement changes and external unknown disturbances, which hinder precision applications. To address this issue, this study explores HLSS principles to develop an accurate system model. Subsequently, an adaptive robust motion control that considers displacement compensation (DCARC) is proposed using the established model. DCARC can learn unknown parameters online and compensate the model more accurately to improve control accuracy. Experiments show that considering the higher order dynamic effects caused by displacement in the system can improve model accuracy and effectively reduce the burden of parameter adaptation and robust feedback terms. High-precision and energy-efficient HLSS motion is verified and realized in the study. The control accuracy of DCARC is 19.4% higher than that of conventional adaptive robust control (ARC). Under experimental conditions, the proposed system can improve energy efficiency by up to five times compared to valve-controlled fixed displacement motor systems (VFDS).

Adaptive Feedback Control for Four-Phase Interleaved Boost Converter Used with PEM Fuel Cell

Fuel cell electric vehicles (FCEVs) are among the devices that have emerged in recent years. To provide electricity to the electric motors, they use a proton-exchange membrane fuel cell (PEMFC) as the primary energy source and a secondary source consisting of an energy storage system (battery or supercapacitors). The addition of these sources to the motors and accessories of a vehicle requires the association of static converters to condition the different power sources. In addition, a high-efficiency and enhanced-reliability power converter is essential to connect the PEMFC to the vehicle’s DC bus. This paper proposes a robust feedback controller for a four-phase interleaved boost converter used with PEMFC. The proposed controller has double loops based on a state-feedback controller, and an inner loop which translates the differential equation of the system into a state representation by linearization around its operation points. The reference current is generated by state feedback in the outer loop; the state variable is defined by using a change variable. The strong robustness and highly dynamic characteristics of the proposed controller are demonstrated through its performance in terms of output voltage, source current, and settling time. The findings indicate that the proposed controller achieves a response time of 20 ms, resulting in an over 50% improvement compared to the controllers referenced in the literature. Additionally, it reduces both current and voltage ripple, keeping them each below 10%. Further, the controller gains synthesis is validated using the linear quadratic regulator (LQR) technique as well as boundary conditions, and its robustness is verified, taking into account the uncertainty of various operating conditions and discrepancies in circuit components. A double-loop super-twisting sliding mode controller, a backstepping control algorithm, and a PI controller are selected for comparison and discussion. Subsequently, the effectiveness of the proposed controller is evaluated through simulation with the parameters of a 500 W fuel cell system.

Control Design and Implementation of Autonomous Robotic Lawnmower

This paper presents the trajectory tracking control design and implementation of feedback linearization (FL) and robust feedback linearization (RFL), applicable to a robotic lawnmower with four mecanum driving wheels. The RFL control design additionally includes a robust control law. These two nonlinear control laws are developed to enable the controlled robotic lawnmower to accurately follow any specified trajectory. The simulation outcomes illustrate that the suggested control law based on RFL displays superior trajectory tracking accuracy and resilience compared to the FL control method in the case of a robotic lawnmower operating under demanding conditions. These conditions encompass environmental disturbances and uncertainties in modeling. The RFL control method also exhibits lower energy consumption compared to the FL control method. Finally, using the RFL controller derived from this study, the error in trajectory tracking in computer simulations and the actual mowing performance have demonstrated outstanding results.

Optimal and simultaneous synthesis of fractional order QFT controllers and prefilters for non-minimum phase hydro power systems

Abstract Ideally, the operating frequency of the power units, working in parallel, must not deviate from its nominal value. However, due to the dynamic nature of the load, operating frequency varies throughout the day; thus, the control of governors in the prime movers is essential to balance out the demand, and prevent any frequency deviation. To address this, present study investigates the design of optimal and robust quantitative feedback theory based (QFT) controllers and pre-filters for single area load frequency control of hydro power systems. Hydropower system model considered in the present study features a right-hand side zero, thus exhibiting non-minimum phase; these characteristics make the control more challenging. Also, the work investigates the optimal design of the QFT controllers and prefilters simultaneously by automating the loop shaping procedure, which else follows a sequential manual process on Nichols charts. The proposed automation also empowers the control designer to predefine the controller structure. In the present work the design of fractional order QFT controllers and pre-filters is considered. The study also compares the proposed work with the methods proposed in the existing literature as well as the optimal controllers obtained using the time domain indices. The obtained results establishes that the developed fractional QFT controller offers good tracking, stability, and robustness to disturbances when compared to existing approaches. The proposed fractional order QFT controllers offer the elimination of the overshoot and the undershoot from the closed loop response of the system; outperforms the existing controllers in terms of disturbance rejection; offers 0% steady-state deviation, while providing improved phase margin (60.1°) for enhanced stability compared to existing controllers. Also, the proposed QFT-GA attains the ideal values for both the peak complementary sensitivity functions; thus, establishing excellent robustness. Also, the proposed controllers ensure adequate tolerance to frequency deviation in case of load change.

AVALIAÇÃO DE PROGRAMAS DE FORMAÇÃO DE PROFESSORES: CRITÉRIOS E IMPACTOS

Considering the incessant and turbulent social changes that permeate today's society, teacher training stands out as a vital path for updating and improving the professionals responsible for teaching and educating. Thus, the objective of teacher training is not limited to the discourses and epistemological bases that support teacher preparation but expands to foster a deep reflection on educational practice and equip professionals with the essential skills to align the profile of the citizen we educate with emerging social demands. Therefore, it becomes imperative to evaluate the results of training programs and actions aimed at teachers, to uncover the consequences of these initiatives and, thus, verify the real effectiveness of training programs aimed at teachers. In this scenario, the importance of evaluating training programs explodes in relevance, revealing itself as a crucial element in the incessant search for educational quality. This document aims to highlight, in a vibrant way, the urgent need to evaluate evaluation levels, identify the appropriate moments for each evaluation modality, and determine the instruments for collecting information. The analysis of the agents involved in this evaluation process will be addressed with intensity, highlighting how these aspects interconnect to create a robust and impactful feedback cycle, aiming to reveal the magnitude of the importance of continuous evaluation in improving teacher training and adapting to constantly changing social dynamics.

Implementation and effectiveness of the cashless banking system

This thesis analyses the implementation and effectiveness of the cashless banking system at Ecobank, focusing on various dimensions such as usability, stakeholder satisfaction, and customer perspectives. A mixed-methods approach was employed, incorporating quantitative and qualitative data from 25 participants to evaluate the system's performance. The analysis reveals that while the cashless banking system is generally well-received, particularly in ease of task completion and overall workflow improvements, there are notable challenges in usability, particularly with interface intuitiveness and performance during peak hours. Stakeholders and customers reported moderate satisfaction, with varying experiences regarding ease of use and reliability. The study concludes that although the cashless banking system has enhanced Ecobank’s service delivery and met broad expectations, further user experience, system performance, and continuous evaluation mechanisms are necessary to optimise its effectiveness and customer satisfaction. Recommendations include focusing on user-centred design, improving scalability for peak demand periods, and establishing robust feedback loops for ongoing system refinement.

Dynamic output feedback robust MPC hybrid fault-tolerant control for discrete uncertain systems: a switching control strategy

To guarantee the control performance of the discrete system under unmeasurable state and partial actuator failure, a robust dynamic output feedback predictive fault-tolerant control method derived from switching strategy is developed. A new iterative error switching model is established, which both ensures tracking performance and lays the foundation for the development of the next switching controller. Based on this model, output feedback switching fault-tolerant controller is developed. Compared with conventional fault-tolerant control methods, the designed controller can be used under the case of unmeasurable states, and it is more fault tolerant and less conservative. According to the Lyapunov stability theory, the robust stability analysis is carried out under normal and fault conditions, respectively. Then, depending on the findings of the stability analysis, sufficient conditions to guarantee the stability of the closed-loop normal and faulty system are derived. Finally, the suggested method's efficacy is confirmed using the injection moulding process as an example.

Influence of Community Participation on Sustainability of Non-Profit Organizations: The Case of Kenya Wildlife Conservancies Association (KWCA)

This paper examines the influence of community participation on the sustainability of non- profit organizations, with a particular focus on the Kenya Wildlife Conservancies Association (KWCA). Using stakeholder theory and participatory development theory as its theoretical framework, the study employed a descriptive research design and utilized stratified and purposive sampling. Data was collected from 100 respondents—including board members, staff, and stakeholders—via structured questionnaires and analyzed using SPSS with multiple regression. The findings demonstrated a significant positive correlation Y = 2.184 + 0.438X1 + Ԑ., between community participation and sustainability of non-profit organizations highlighting that community engagement fosters ownership, responsibility, and long-term support. The study revealed that community participation enhances resource mobilization, accountability, and transparency within non-profit organizations. Respondents emphasized the importance of community involvement in achieving these outcomes, aligning with prior research by Smith et al. (2020) and Mwangi and Njenga (2019), which also underscored the positive impact of community engagement on non-profit effectiveness and sustainability. By integrating community members into decision-making processes, non-profits can leverage local knowledge and skills, ensuring continued support and effective management. Based on these insights, several recommendations are proposed for KWCA and similar organizations. It is essential to prioritize and expand community involvement by developing more inclusive and interactive engagement programs. Establishing robust feedback mechanisms will facilitate community input and foster a sense of ownership. Additionally, investing in capacity-building initiatives to equip community members with the necessary skills and knowledge is crucial. These measures are expected to enhance community engagement, improve program effectiveness, and bolster the overall sustainability of KWCA’s initiatives.

Research on Longitudinal Control of Electric Vehicle Platoons Based on Robust UKF–MPC

In a V2V communication environment, the control of electric vehicle platoons faces issues such as random communication delays, packet loss, and external disturbances, which affect sustainable transportation systems. In order to solve these problems and promote the development of sustainable transportation, a longitudinal control algorithm for the platoon based on robust Unscented Kalman Filter (UKF) and Model Predictive Control (MPC) is designed. First, a longitudinal kinematic model of the vehicle platoon is constructed, and discrete state–space equations are established. The robust UKF algorithm is derived by enhancing the UKF algorithm with Huber-M estimation. This enhanced algorithm is then used to estimate the state information of the leading vehicle. Based on the vehicle state information obtained from the robust UKF estimation, feedback correction and compensation are added to the MPC algorithm to design the robust UKF–MPC longitudinal controller. Finally, the effectiveness of the proposed controller is verified through CarSim/Simulink joint simulation. The simulation results show that in the presence of communication delay and data loss, the robust UKF–MPC controller outperforms the MPC and UKF–MPC controllers in terms of MSE and IAE metrics for vehicle spacing error and acceleration tracking error and exhibits stronger robustness and stability.

Robust finite-time output feedback stabilisation for a class of uncertain planar systems with asymmetric output constraints

This paper considers the finite-time output feedback stabilisation (FTOFS) problem for a class of uncertain planar systems with asymmetric output constraints. The presence of unknown control coefficients, unknown measurement sensitivity and asymmetric output constraints makes the system under consideration essentially different from those in the existing related works. By constructing a new barrier Lyapunov function and applying homogeneous system theory, a simple proportional-derivative like finite-time output feedback controller is explicitly constructed, which only utilises the output information. A rigorous proof demonstrates that not only the closed-loop system is finite time stable, but also the requirement of asymmetric output constraint can be achieved. The novelty of the control approach lies in that it is capable to handle the FTOFS problem for uncertain planar systems with or without asymmetric output constraints in a unified manner, without changing the control structure. The efficiency of the proposed theoretical results are confirmed by simulation results.

Robust [formula omitted] output feedback control for polynomial discrete-time systems

This paper aims to design a robust output feedback controller with H∞ performance for polynomial discrete-time systems (PDTS). This is due to the lack of research available on PDTS’ output feedback control especially when uncertainty is considered in the system. To be specific, the norm-bounded uncertainties are considered instead of polytopic uncertainties and then a so-called ‘scaled’ system is established to relate the robust H∞ and the nonlinear H∞ output feedback control problem. The integrator approach is introduced to overcome the nonconvexity issue when the polynomial Lyapunov function is selected. The controller is obtained by solving the sufficient conditions which are formulated in Polynomial Matrix Inequalities (PMIs) which is then converted into Sum of Squares (SOS) form. Semidefinite Programming (SDP) is used to obtain the results. Finally, the efficacy of the method is shown through numerical examples.

MPC Optimization Algorithm and Strategy for HVAC System under Smart City Construction

As a giant in energy consumption, buildings urgently need to optimize control strategies for the main energy consuming equipment inside buildings. It is of great significance to design advanced control algorithms to improve the efficiency of the main energy consuming equipment in buildings, namely air conditioning, in the current energy shortage. The model predictive control algorithms and strategies were used in this study to control the HVAC system to improve the energy utilization of the city. Then linear matrix inequality with robust model predictive feedback controller was used to optimize and get the model predictive control optimization algorithm. The research results showed that, under the influence of different factors, the three regions controlled by the model predictive control optimization algorithm showed a little overshooting in the initial state. But it was quickly corrected after adjustment. Meanwhile, the average tracking error of temperature and humidity in each region was 0.139◦ C and 0.13g/kg dry air, respectively. The average predicted mean vote was 0.32. In actual office buildings, the proposed algorithm controlled the temperature within the reference value range of 0.1◦ C throughout the entire process. The total electricity consumption and electricity price costs were reduced by 12.11% and 22.54%, respectively. In summary, the proposed method has good performance for HVAC system application, which can effectively realize energy saving and emission reduction and improve human comfort. This method makes important contributions to promote the construction of smart cities and the development of green buildings.

Practical tracking control for a class of uncertain MIMO nonlinear systems with unmatched disturbances

This paper studies the output tracking control problem for a class of uncertain MIMO nonlinear systems. The motivation comes from how to deal with unknown coupling system dynamics between subsystems and achieve the desired tracking when the system has parameter uncertainties and external disturbances. The difficulty is to guarantee that tracking errors enter an arbitrarily prescribed neighbourhood within a finite time. Based on the construction of a time-varying dynamic gain associated with tracking errors and the effective manipulation of nonlinear parametrization, a novel robust feedback controller is built up to ensure the boundedness of all closed-loop signals and the convergence of tracking errors to a small neighborhood approaching the origin in a finite time. Finally, the feasibility of control strategy is verified by numerical and practical examples.

Current trends and perspectives of scoliosis research society travel fellows

Abstract Purpose This study aims to measure the impact of the Scoliosis Research Society’s travel fellowship on a spinal surgeon’s career. Methods A non-incentivized survey was sent to 78 previous SRS junior travel fellows from 1993 to 2021. The questionnaire assessed fellowship influence on academic and administrative positions, professional society memberships, and commercial relationships. The trend of these quantitative measures was created according to a compounded annual growth rate (CAGR) calculation of the reported values. The Scopus database was queried for all fellows’ publication counts and h-index before the fellowship, as well as 3 years, 5 years, and currently after the fellowship. A control cohort of matched surgeons who did not participate in travel fellowships was used to compare research productivity measures relative to travel fellows. Results This study had a 73% response rate. Over the periods of 3–5 years after the fellowship, and up to the present, the mean publication count increased by 31.0%, 31.6%, and 46.4%, respectively. Over the same interval, the mean h-index increased by 19.5%, 17.3%, and 11.3%, respectively. From the year of their respective fellowship to present day, the fellows observed a mean CAGR of + 3.2% in academic positions, + 6.7% in administrative positions, + 2.3% in society memberships, and + 4.7% in commercial relations. Previous fellows concurred the fellowship changed their clinical practice (42.1% Strongly Agree, 36.8% Agree), expanded their network (71.9% Strong Agree, 24.6% Agree), expanded their research (33.3% Strongly Agree, 54.4% Agree), and improved their surgical technique (33.3% Strongly Agree, 49.1% Agree). Conclusion Robust feedback from previous fellows suggests a traveling fellowship has a meaningful impact on a surgeon’s research productivity and career achievements.

Robust higher order sliding mode control of grid‐forming converters with LCL filter in weak grid scenarios for fast frequency support

AbstractThis paper presents a nonlinear higher‐order sliding mode control (HO‐SMC) designed for a droop control‐based grid‐forming converter. In weak grid scenarios, where the rate of change of frequency is notably high, achieving a rapid frequency response becomes imperative. The stable operation of a grid‐forming converter using droop control, coupled with classical vector control that employs cascaded voltage and current loops (multiloop) with PI controllers, faces limitations when higher droop coefficients are applied. This constraint on the application of classical vector control in weak grid conditions necessitates alternative solutions. Operating as a grid‐forming converter, the grid‐connected converter with an LCL filter represents a second‐order system. HO‐SMC mitigates the switching challenges associated with conventional SMC by integrating robust feedback linearized control. A graphical method is proposed for designing the switching gain using Lyapunov's direct method to counteract the impact of a matched disturbance. The study demonstrates that the implementation of HO‐SMC in the grid‐forming converter enhances fast frequency response by increasing the gain margin of the power frequency loop. Finally, it is illustrated that the proposed control method also improves the transient response of the converter.

Evaluating community-embedded elder care: A case study of supply and demand in Hangzhou, China.

With China's urbanization and demographic shifts significantly affecting elder care, this study examines the alignment of community-based elder care services in Hangzhou's Hemu Community. It addresses the gap in understanding how these services meet the needs of an aging population in a rapidly changing social context. A comprehensive mixed-methods approach was utilized, involving interviews with community residents, observations of elder care service operationsand thorough document analysis. The objective was to evaluate the adequacy, utilizationand satisfaction levels concerning these elder care services. The research identified that, although the services generally meet the community's needs, there are notable challenges in content specificity, quality assuranceand promotional efforts. These challenges lead to resistance among older adults. Additionally, issues with service visibility and the lack of robust feedback mechanisms were noted. This study highlights the critical need for a cooperative strategy involving government, community organizations, social entitiesand businesses in enhancing elder care services. It suggests that improvements in service visibility, content qualityand targeted promotion are crucial to address the evolving needs of the aging population and to reduce reluctance in service utilization.