Search Results (10)

To tackle the challenges of poor stability during real-time random gait switching and precise trajectory control for hexapod robots under limited stride and steering conditions, a novel real-time replanning gait switching control strategy based on an omnidirectional gait and fuzzy inference is proposed, along with an attitude control method based on the single-neuron adaptive proportional–integral–derivative (PID). To start, a kinematic model of a hexapod robot was developed through the Denavit–Hartenberg (D-H) kinematics analysis, linking joint movement parameters to the end foot’s endpoint pose, which formed the foundation for designing various gaits, including omnidirectional and compound gaits. Incorporating an omnidirectional gait could effectively resolve the challenge of precise trajectory control for the hexapod robot under limited stride and steering conditions. Next, a real-time replanning gait switching strategy based on an omnidirectional gait and fuzzy inference was introduced to tackle the issue of significant impacts and low stability encountered during gait transitions. Finally, in view of further enhancing the stability of the hexapod robot, an attitude adjustment algorithm based on the single-neuron adaptive PID was presented. Extensive experiments confirmed the effectiveness of this approach. The results show that our approach enabled the robot to switch gaits seamlessly in real time, effectively addressing the challenge of precise trajectory control under limited stride and steering conditions; moreover, it significantly improved the hexapod robot’s dynamic stability during its motion, enabling it to adapt to complex and changing environments. Full article

A multi-objective intelligent optimization algorithm-based attitude control strategy for magnetorheological semi-active suspension is proposed to address the vehicle attitude imbalance generated during steering and braking. Firstly, the mechanical properties of the magnetorheological damper (MRD) are tested, and the parameters in the hyperbolic tangent model of the magnetorheological damper are identified through experiments. Secondly, a simulation model of the whole vehicle multi-degree-of-freedom vehicle dynamics including magnetorheological damper is established, and the whole-vehicle Linear Quadratic Regulator (LQR) controller is designed. Then, the optimization design model of the joint vehicle controller and vehicle dynamics is established to design the optimization fitness function oriented to the body attitude control performance, and the attitude optimal controller is calculated with the help of multi-objective intelligent optimization algorithm. Simulation results show that the proposed control method is able to improve the body roll angle, body pitch angle, and suspension dynamic deflection well on the basis of ensuring no deterioration in other performance indexes, ensuring good attitude control capability of the vehicle and verifying the feasibility of the control strategy. Full article

In addressing the limitations of traditional steering stability control strategies applied to distributed-drive electric vehicles (DDEVs)—which primarily focus on measuring yaw rate and sideslip angle and may result in loss of control during steering maneuvers—this study conducts a more comprehensive analysis of DDEVs’ steering control stability. It specifically investigates the relationships among the lateral positions of both the front and rear wheels, the slip ratios, and the angular orientation of the vehicle’s body during steering processes. Furthermore, a dual-layer steering stability control system aimed at enhancing the steering stability performance of DDEVs is introduced. This control system consists of two components: a lateral controller and a longitudinal controller. The lateral controller aims to establish clear linkages among four key variables, the front and rear wheel sideslip angles, yaw rate, and sideslip angle, and then to compute the necessary active front wheel steering angle and corresponding yaw moment based on the current vehicle body attitude. The findings indicate that, in comparison to the conventional DDEV controller, the proposed two-layer controller achieves substantially closer alignment to the reference curve during steering, with the accuracy increased by a factor of approximately 5 to 20. These results unequivocally affirm the efficacy and viability of the proposed approach. Full article

Environmental unsustainability in coupled human–nature systems is accumulating. Yet, there is no accreditation requirement for unsustainability resolution competency in higher education. Thus, a new and complete representation of the pedagogy for unsustainability resolution competence has been induced, using what is already available and working. The nature of unsustainability problems points to collaboration and holism attitudes. Resolution requires social skills, namely participation, perspective taking, and the generation of social capital, and cognitive skills, namely project management, knowledge building, and modeling. Resolution is scaffolded in three successive steps during the collaborative process within a systems approach: (i) collapse complexity; (ii) select a path/trajectory; and (iii) operationalize a plan. The hierarchically cumulative abilities toward unsustainability resolution competence are to source data and information about the coupled human–nature system (SEARCH); simplify the dynamics of the human–nature system (SIMULATE); generate and test alternative paths and end points for the coupled human–nature system (STRATEGIZE); chose a favorable path among the available alternatives (SELECT); operationalize the favorable path into a plan (strategy–program–project) with measurable management and policy objectives (IMPLEMENT); and develop criteria/indicators to monitor and adjust when necessary the implementation of the plan toward system goals (STEER). For each one of these learning objectives, the Bloom’s taxonomy and a progression from behaviorist through cognitivist to constructivist tools apply. The development of mastery requires the comparison and contrast of many similar cases with the same unsustainability problem and project-based learning with specific cases for deep learning. In this way, it is the resolutions of unsustainability in human–nature systems that will be accumulating. Full article

Here, the role of business managers in Poland and Germany in creating responsible business was analyzed. The authors examined CSR strategies, challenges in balancing interests and integrating CSR principles with business practices. They emphasize the importance of education and the active involvement of managers in CSR strategies for the company’s long-term benefits. The article uses three key research methods. The first is a review of the Polish and foreign literature, allowing for an understanding of the global context of CSR. The second method is the analysis of CSR reports from Poland and Germany, giving insight into practices and standards in these countries. The third method is research based on a questionnaire survey conducted in Poland and Germany, enabling a direct understanding of the attitudes and practices of managers. Polish companies lean towards sustainable purchasing and training more than their German counterparts, pointing to a nuanced approach to CSR in Poland. Meanwhile, German firms appear more invested in community and environmental programs, highlighting their particular emphasis on certain social and environmental dimensions of business. There is a clear commitment to CSR in both countries, but the varied nature of the initiatives suggests differing cultural or regulatory influences. Enhancing CSR awareness, particularly around sustainability education and emission reductions, emerges as a priority for both nations. The data indicate that managers are crucial in steering CSR practices, with their active involvement often leading to positive outcomes. The study provides an analysis of current CSR landscapes in Poland and Germany. Full article

Renewable energy sources—which are available in abundance all around us and are provided by the sun, wind, water, waste, and heat from the Earth—are replenished by nature and emit little to no greenhouse gases or pollutants into the air. This paper builds upon a preceding study that examined beliefs, perceptions, and attitudes regarding renewable energy technologies. In this study, we examine the implications renewable energy sources may have on science, technology policies, and education. This study embraced a sequential mixed-methods methodology to accomplish its objectives. The primary goal of this study was to ascertain the impact of global warming, education, and renewable energy on healthcare expenditure. In order to determine the impact of renewable energy on health care expenditure, the present research study coupled renewable energy with gross domestic product (GDP). Based on the long-term outcomes derived from our Fully Modified Ordinary Least Squares (FMOLS) and Dynamic Ordinary Least Squares (DOLS) estimators, GDP, renewable energy, and education were found to be adversely correlated with healthcare expenditure. To collect data, we conducted interview sessions, which were subsequently complemented by a survey that was completed by 400 respondents (specifically chosen research participants). We then conducted thematic analyses. The findings of this study underscore a compelling inverse relationship linking GDP, renewable energy integration, and education with healthcare spending. Regions displaying lower healthcare outlays are seemingly less strained ecologically due to their judicious utilization of renewable energy sources. Furthermore, based on our findings, a noteworthy correlation between healthcare expenditure and global warming was observed, underscoring the potential escalation of financial burdens with intensifying climate shifts. In light of our findings, advocating for the amplification of renewable energy deployment emerges as a prudent strategy to fortify public health while mitigating healthcare expenses. Augmenting investments in education acts as a pivotal lever to steer sustainable growth. It is noteworthy that the survey participants’ level of familiarity with renewable energy technology was not found to be connected to their educational backgrounds, revealing a disparity in knowledge. The prevailing unfamiliarity with sustainability principles among the respondents underscores the need for widespread awareness initiatives. This study acts as a holistic exploration of the ramifications of renewable energy on healthcare expenditure; this is intertwined with the complex tapestry of global warming and education. The implications of renewable energy reverberate across policy and practice, accentuating the urgency of sustainable energy adoption for the betterment of public health and economic resilience. Future studies should focus on conducting more nuanced assessments of socio-economic aspects and generate strategies for bridging knowledge gaps among diverse stakeholders. Full article

Kinematic orbit determination (KOD) of low earth orbit (LEO) satellites only using single-frequency global navigation satellite system (GNSS) data is a suitable solution for space applications demanding meter-level orbit precision. For some small LEO satellites with the sun-pointing attitude mode, the rotation of the GNSS antenna radiation pattern changes the observation noise characteristics. Since the rotation angle information of the antenna plane may not be available for most low-cost missions, the true elevation cannot be computed and a general elevation-dependent weighting model remains invalid for the onboard GNSS observations. Furthermore, the low-stability GNSS receiver clock oscillator of the LEO satellite at high speeds makes single-frequency cycle slip detection ineffective and difficult since the clock steering events occur frequently. In this study, we investigated the improved KOD strategy to improve the performance of orbit solution using single-frequency GPS and BeiDou navigation satellite system (BDS) observations collected from the Luojia-1A satellite. The weighting model based on exponential function and signal strength is proposed according to the analysis of satellite attitude impact, and a joint single-frequency detection algorithm of receiver clock jump and cycle slip is investigated as well. Based on the GPS/BDS-combined KOD results, it is demonstrated that the clock jump and cycle slip can be properly detected and observations can be effectively utilized with the proposed weighting model considering satellite attitude, which significantly improves the availability and accuracy of orbit solution. The number of available epochs is increased by 12.9% benefitting from this strategy. The orbital root mean square (RMS) precision improvements in the radial, along-track, and cross-track directions are 22.1%, 16.4%, and 6.5%, respectively. Combining BDS observations also contributes to orbit precision improvement, which reaches up to 28.8%. Full article

In this study, we analyzed the imaging maneuver time, retargeting maneuver time, and attitude maneuvering characteristics in the imaging section (Phase 1) and retargeting maneuver section (Phase 2) when taking multiple-target images in squint spotlight mode in a single pass of a passive SAR satellite. In particular, the synthetic aperture time and attitude maneuvering characteristics in the staring and sliding spotlight modes that can image the wider swath width while maintaining high resolution were compared and analyzed. In the sliding spotlight mode, the rotation center was located below the ground surface when the satellite was maneuvering towards the target. Steering and sliding maneuvers were performed when targeting, and the synthetic aperture time of the sliding spotlight was longer than that of the staring spotlight because overlapping imaging was performed on the point target. The satellite maneuvering during imaging can be considered as a time-fixed problem, because it was performed within synthetic aperture time according to resolution, incidence angle, swath width, etc., by minimizing the Doppler centroid variation. In order to optimize the retargeting maneuver time, an optimal analysis of the attitude maneuvering was carried out and the validity of the optimal analysis algorithm was confirmed. Finally, the scenario was analyzed by assuming a problem of imaging four targets with 5 × 5 km swath width in a 20 km × 20 km densely populated area. It was confirmed that if a squint angle of ±12 degrees is provided in a single pass, four high resolution images of 5 km × 5 km can be imaged in the sliding spotlight mode. Full article

Vaccine hesitancy (uncertainty or unwillingness to receive vaccinations) is a major barrier to manage the COVID-19 pandemic in the long term. This study aimed to explore the prevalence of COVID-19 vaccine hesitancy among the public in Kuwait, to understand their attitudes towards vaccines in general, and to identify predictors of COVID-19 vaccine hesitancy. A cross-sectional study was conducted among 4147 adults aged ≥ 18 years. The snowball sampling strategy was used for data collection through social media and e-mails. A total of 3061 (73.8%) respondents indicated that they were vaccinated or intending to be vaccinated against the COVID-19 infection, while 1086 (26.2%) expressed their vaccine hesitancy. The most common reasons for vaccine hesitancy were the concerns about the vaccine’s possible side effects, its rushed development, and its efficacy in preventing the infection. Over half (57.2%) of respondents expressed intermediate to high levels of negative attitude towards vaccines in general. On the multivariable logistic regression analysis, the findings revealed that vaccine hesitancy was significantly more prevalent among respondents aged 30–64 years; females; married or divorced; residents of Hawalli, Al-Farwaniyah, Al-Jahra, and Mubarak Al-Kabeer; had intermediate monthly average income; non-smokers; not feeling worried about catching the infection; do not know whether any of their family members have been infected or died because of COVID-19 infection; do not have a large extent of confidence in the Kuwait health system’s ability to handle the pandemic; did not receive influenza vaccine during the last year; refused or elected to forego a doctor-recommended vaccine; did not receive adequate information from the public health authorities/healthcare providers about the COVID-19 vaccines; none of their first-degree family members received or were intending to receive the vaccine; and expressed intermediate to high levels of negative attitudes towards vaccines in general. The present findings provide a steer as to the groups that most need to be reached to increase the rates of vaccine uptake. Full article

In the process of vehicle chassis electrification, different active actuators and systems have been developed and commercialized for improved vehicle dynamic performances. For a vehicle system with actuation redundancy, the integration of individual chassis control systems can provide additional benefits compared to a single ABS/ESC system. This paper describes a Unified Chassis Control (UCC) strategy for enhancing vehicle stability and ride comfort by the coordination of four In-Wheel Drive (IWD), 4-Wheel Independent Steering (4WIS), and Active Suspension Systems (ASS). Desired chassis motion is determined by generalized forces/moment calculated through a high-level sliding mode controller. Based on tire force constraints subject to allocated normal forces, the generalized forces/moment are distributed to the slip and slip angle of each tire by a fixed-point control allocation algorithm. Regarding the uneven road, H∞ robust controllers are proposed based on a modified quarter-car model. Evaluation of the overall system was accomplished by simulation testing with a full-vehicle CarSim model under different scenarios. The conclusion shows that the vertical vibration of the four wheels plays a detrimental role in vehicle stability, and the proposed method can effectively realize the tire force distribution to control the vehicle body attitude and driving stability even in high-demanding scenarios. Full article