Search results

This paper aims to deal with the design of new hybrid approach for the assistance of the flexion extension movement of the knee joint.

The control approach combines the use of a knee joint orthosis along with functional electrical stimulation (FES) within an assist-as-needed paradigm. An active impedance controller is used to assist the generation of muscular stimulation patterns during the extension sub-phase of the knee joint movement. The generated FES patterns are appropriately tailored to achieve flexion/extension movement of the knee joint, which allows providing the required assistance by the subject through muscular stimulation. The generated torque through stimulation is tracked by a non-linear disturbance observer and fed to the impedance controller to generate the desired trajectory that will be tracked using a standard proportional derivative controller.

The approach was tested in experiments with two healthy subjects. Results show satisfactory performances in terms of estimating the knee joint torque, as well as in terms of cooperation between the FES and the orthosis actuator during the execution of the knee joint flexion/extension movements.

The authors designed a new hybrid approach for the assistance of the flexion extension movement of the knee joint, which has not been studied yet. The control approach combines the use of a knee joint orthosis along with FES within an assist-as-needed paradigm.

The purpose of this paper is the control of lower limb orthosis acting at the knee joint level for a passive rehabilitation purpose.

A control law, based on a saturated proportional derivative controller, is proposed in order to drive the shank-foot-orthosis system along a desired trajectory.

The proposed control law is tested in real time using the orthosis EICOSI of the LISSI-Laboratory. The experiments show that the proposed control law is capable of providing satisfactory trajectory tracking performance given only the knee joint angle measurement. Moreover, the control law is robust with respect to external disturbances.

Robust control of an actuated lower limb orthosis.

Assistive technology products are designed to provide additional accessibility to individuals who have physical or cognitive difficulties, impairments and disabilities. The purpose of this paper is to deal with the control of a knee joint orthosis intended to be used for rehabilitation and assistive purpose; this control aims to reduce the influence of the uncertainties and eliminating the external disturbances in the system.

This paper deals with the robust adaptive sliding mode controller (ASMC) of human-driven knee joint orthosis system with mismatched uncertainties and external disturbances. The shank-orthosis system has been modeled and its parameters have been identified. This control reduces the effect of parameter uncertainties and external disturbances on the system performance and improves the system robustness as results. The ASMC was designed to offer the possibility to track the state of the reference model. Moreover, the Lyapunov stability theory was used to study the asymptotical stability of the ASMC.

The advantage of the robust ASMC method is the tracking precision and reducing the required time for eliminating external disturbances and uncertainties. The experimental results show in real-time in terms of stability and present that the advantages of this control approach are the position tracking and robustness.

In this paper, to deal with the parameter uncertainties of the human-driven knee joint orthosis, an ASMC was successfully applied based on sliding mode and Lyapunov stability theory. It has good dynamic response and tracking performance. Besides, the adaptive algorithm is simple, easy to achieve and has good adaptability and robustness against the parameter variations and external disturbances. The design technique is simple and efficient. The development of this control takes into consideration the perturbation, allowing to track a desired trajectory.

The application of the sliding mode control has two obstacle phenomena: chattering and high activity of control action. The purpose of this paper concerns a novel super-twisting adaptive sliding mode control law of a human-driven knee joint orthosis. The proposed control approach consists of using dynamically adapted control gains that ensure the establishment, in a finite time, of a real second-order sliding mode. The efficiency of the controller is evaluated using an experimental set-up.

This study presents the synthesis of a robust super-twisting adaptive controller for the control of a lower limb–orthosis system. The developed control strategy will take into consideration the nonlinearities as well as the uncertainties resulting from the dynamics of the lower limb–orthosis system. It must also guarantee a good follow-up of the reference trajectory.

The authors first evaluated on a valid subject, the performances of this controller which were studied and compared to several criteria. The obtained results show that the controller using the Adaptive Super-Twisting algorithm is the one that guarantees the best performance. Validation tests involved a subject and included robustness tests against external disturbances and co-contractions of antagonistic muscles.

The main contribution of this paper is in developing the adaptation super-twisting methodology for finding the control gain resulting in the minimization of the chattering effect.

The purpose of this study is to understand the situation of hotels and tourism industry in Malaysia during and in post Covid-19 and to mitigate indirect damage caused by COVID-19 to the hotel business and tourism industry by examining the factors that have an influence on hotel’s customer satisfaction rating and revisit intention through an integration of service quality (SERVQUAL) framework and expectation-confirmation theory (ECT).

The SERVQUAL and ECT were considered the underpinning theoretical models but are integrated and extended by including a few additional variables. Data were collected from 458 respondents of travelers and hotel customers in Malaysia and analysed by applying partial least squares structural equation model technique.

The empirical results established that significant positive relationships exist between the three newly emerged independent variables (IVs), namely, hygienic practice, greenness of service and digitalization and hotel customer satisfaction towards hotel revisit intention, and only two variables from SERVQUAL, namely, reliability and assurance, have a significant relationship with hotel customer satisfaction towards hotel revisit intention. The results reveal that customer satisfaction has significant direct effect between above-mentioned IVs and customers revisit intention.

The use of purposeful sampling method in only one country might limit the generalizability of the results. Future research should be planned to duplicate the current study using a sizable sample of participants from multiple countries and include other related factors related to the pandemic phenomena such as safety, hotel location and health value offered.

Theoretical findings imply that service quality is a dynamic theory that should be examined continuously to achieve sustainable and resilient performance in today’s competitive business environment, as some modifications inevitably occur over time and new factors could be emerged. Regarding practical implications, study findings proved the great significance of assurance, reliability, digitalization, greenness and hygienic practices on customer satisfaction towards intention to revisit to hotel. Therefore, it is critical for hotel management to retain hotel business industry in a way that fits and matches customer’s health protection, meets customer’s newly prompted expectations and needs and ensures resilience during unsettled times.

This study is unique as the newly emerged variables are included in the research framework, and thus it helps to close the literature gap by introducing an integrated SERVQUAL and ECT theoretical model, which rarely performs in this context and can be replicated or extended with validated scales. This study contributes to enhancing hotel and tourism sustainable service quality performance to achieve myriad economic and health values.

Previous studies equated information technology (IT) with the notion of effective resources. ITs improved firms’ competitive advantage and innovativeness. Yet, far fewer studies investigated types of IT competencies that corresponded to innovation capabilities, particularly in developing countries. The aim of this paper is to provide an investigation concerning the types of IT competencies and examine their influence on the innovation capabilities across high-tech firms.

A survey was randomly distributed to 274 respondents across four main sectors of Malaysian high-tech firms. The main sectors were electric and electronic, aerospace, computers and office machinery and pharmaceuticals. A structural equation model, Amos, was used to analyse data.

Three findings were surmised. First, IT competencies driven by IT infrastructure, alignment, management affected high-tech firms’ innovation capabilities. Second, absorptive capacity (AC) partially determined the relationship between IT infrastructure and IT alignment and innovation capabilities. AC also determined the relationship between IT management and innovation capabilities. The significance of IT competencies in the improvement of innovation capabilities was presented as a key predictor in bolstering high-tech manufacturing firms’ competitive advantage.

Two points on novelty were presented. First, by conceptualising IT competencies from resource-based theory (RBV), a shift in understanding RBV was presented. Second, alternative key predictors concerning how IT competencies could improve aspects of AC and innovation capabilities were presented.

This study aims to examine the results of structural equation modelling in applying unified theory of acceptance and use of technology in adopting Islamic Fintech among millennials in Malaysia via measurement and structural models.

A total of 418 valid responses have been obtained from Malaysians who are using Islamic Fintech. Before the data is analysed into measurement and structural modelling preliminary analysis such as common method bias has been conducted.

All the requirements for model fit in this study have been achieved. Four exogenous constructs are performance expectancy, effort expectancy, social influence and facilitating condition. The mediating construct is behavioural intention, whereas the endogenous variable is user adoption. All exogenous constructs show significant p-values except for effort expectancy.

This study offers important implications, specifically for the digital economy that is currently making its way throughout every aspect of human life, namely, social, religious, financial transaction, entertainment and others. The impact of the digital economy can be traced through the emergence of Fintech. The adoption of Islamic Fintech is one of the least discussed areas academically, therefore, this study is considered necessary to explore the prediction of consumer behaviour in Islamic Fintech adoption as a part of the digital economy in Malaysia.

This study fills the perceived gap in the existing financial technology literature by assessing Islamic financial technology adoption via measurement and structural modelling.

This paper aims to produce lightweight concrete by combining aerated concrete with expanded polystyrene beads concrete to create structural aerated-polystyrene lightweight concrete that satisfies the criteria of sustainability for thermal and sound insulation properties and the structural criteria of having satisfactory compressive strength for structural elements.

The experimental study was carried out to reach the largest compressive strength while maintaining the lowest possible density by preparing nine mixes of concrete, involving different ratios of aluminum waste powder and polystyrene beads as 0%, 0.2% and 0.3% and 0%, 0.1% and 0.2%, respectively, by weight of cement to produce the lightweight concrete with different densities. The performance of mechanical properties, thermal conductivity, ultrasonic pulse velocity, density, modulus of elasticity, acoustic impedance and scanning electron microscopy were studied and discussed.

Results showed that aerated-expended polystyrene beads concrete had the most suitable properties when the proportions of aluminum waste powder and expanded polystyrene beads were 0.2% and 0.1%, respectively. The compressive strength, density, thermal conductivity and acoustic impedance were 38.5 MPa, 1,768 Kg/m³, 0.358 W/(m.k) and 4.91 Kg/m² s, respectively.

The experimental work was done using aluminum scrap waste powder as an expanding agent to produce aerated concrete and combining it with expanded polystyrene bead concrete to produce structural aerated-polystyrene concrete, which contains fine materials (silica fume and local natural raw limestone) and superplasticizers.