Abstract: This paper presents a novel application of the Tensor Product Model Transformation: the approximation of fuzzy control and estimation laws. In order to illustrate this application, a thermoelectric controlled chamber was built using peltier coolers and an H Bridge. Using 5 digital temperature sensors, a Takagi-Sugeno discrete time fuzzy model of the system was found with system identification techniques. A control and an estimation law were designed using state of the art LMI conditions for fuzzy systems. Making use of the Tensor Product Model Transformation, these control and estimation laws were approximated/simplified and implemented on a microcontroller. The results obtained from these simplified laws show that this is a viable option and allows the use of cheap microcontrollers in cases where it would not be able to implement the control and estimation laws.
Keywords: Tensor Product Model Transformation; Hinf model reference control; Takagi-Sugeno observer; LMI
Abstract: Most of the discretization approaches for uncertain linear systems make use of the series representation of the matrix exponential function and truncate the summation after a certain order. This usually leads to discrete-time uncertain polytopic models described by polynomial matrices with multiple indexes, which usually means that the higher the order used in the approximation, the higher the number of linear matrix inequalities (LMI) needed. This work, instead, proposes an approach based on a grid of the possible values for the matrix exponential function and an application of the tensor product model transformation technique to find a suitable polytopic model. Numerical examples are presented to illustrate the advantages and the applicability of the proposed technique.
Keywords: Discretization; LMIs; Uncertain Systems; Tensor Product Model Transformation
Abstract: This paper proposed a control design approach based on tensor product models for perching maneuvers of fixed-wing aircraft. The highly nonlinear longitudinal dynamics of perching maneuvers is transformed into a tensor product model. The interpolation technique is investigated to reduce the conservatism of the convex tensor product model. The properties of the time derivatives of premise membership functions are utilized in the control design process to further reduce the control conservatism. The proposed method is demonstrated with simulation results.
Keywords: perching maneuvers; Tensor product model; Flight control; Parallel distributed compensation control
Abstract: Large spacecrafts undertaking long-life mission greatly suffer from the nonlinear fuel slosh when altering the orbit or maneuvering, which leads to the downgrade on the performance and even stability of the body attitude control by unintentionally generating the huge disturbance thrust. In order to specifically address this solid-liquid coupling problem for a kind of spacecrafts when altering orbit, a nonlinear control method based on Tensor Product (TP) Model transformation is proposed to make a quick response control of the translational velocity vector and the attitude of the spacecraft. Based on the derived polytopic system from TP model transformation, the controller design can guarantee the robust against the uncertainties and disturbances for all system sets within the bounds. The proposed solution also offers an approximation tradeoff so that both the complexity of the TP model and the controller design can be dramatically minimized. The simulation results for spacecrafts with practical specification verify that the design method can make the spacecraft asymptotically stable and demonstrate the effectiveness of the proposed controller.
Keywords: Nonlinear control; TP model transformation; fuel slosh; high-order singular value decomposition.
Abstract: Besides nonlinearity, high coupling and parameter uncertainties, the design of a hypersonic flight control system still faces challenges due to the unstable dynamics under various flight conditions and to the presence of state constraints required by a scramjet. This paper presents a state and input constrained control method for the longitudinal motion of an air-breathing hypersonic vehicle through combining tensor product (TP) model transformation and the command governor approach. This method consists of three steps. Firstly, the paper applies the tensor product (TP) model transformation, making the state space matrices depend on the vector Ɵ of time varying parameters. Secondly, it uses LQ (Linear Quadratic) method to design a set of controllers in the vertex of the TP model, and then, the controllers are checked with the parallel distributed compensation (PDC) controller design framework to ensure global stability and improving control performance. Thirdly, it introduces a command governor (CG) device for command optimization, which modifies the command signal to avoid state and input violations. The significance of this method mainly lies in its capability to avoid excessive flight constraints under various flight conditions. In order to demonstrate the effectiveness of this method, we carried out numerical simulations of the air-breathing hypersonic vehicle in its climbing phase which has state constraints and actuator constraints.
Keywords: tensor product (TP) model; linear matrix inequalities (LMI); constrained control; parallel distributed compensation (PDC); command governor (CG)
Abstract: The current work investigates tumor growth control under antiangiogenic targeted molecular therapy by use of Tensor Product (TP) transformation. During the dynamics of the tumor growth we have considered that the tumor volume x₁(t) is measurable, while due to the lack of information about the second state x₂(t) (the inhibitor level in the serum), we have developed an appropriate Extended Kalman Filter (EKF) to estimate it. We applied different quasi Linear Parameter Varying (qLPV) models during the design of the EKF and the controller. Tensor Product model transformation method completed with Linear Matrix Inequality based optimization have been applied to design the main controller. The reference signals were generated by trajectory tracking kind control based on Inverse Dynamic Control - Proportional Derivate compensator, applied it on the ”simulated” (original) model. We did not consider any state disturbance. However, we have taken into account sensor noise in accordance with the properties of the model. We have found that all of the control goals have been satisfied with the developed control framework: (i) the tumor volume was lower than 1 mm³ at the end of the therapy; (ii) the developed models have approached each other with good accuracy; (iii) the totally injected inhibitor level was physiologically acceptable.
Keywords: Antiangiogenic Targeted Molecular Tumor Therapy, Tensor Model transformation, Linear Parameter Varying, Linear Matrix Inequality, Parallel Distributed Control
Abstract: The paper investigates how workflows can be communicated and shared through linguistic descriptions, digital content and technological tools. We focus primarily on the content and digital tools of e-learning and VR learning. However, the results of the paper can be applied to collaborative workflows in general. The paper compares the effectiveness of three techniques, ranging from well-known to radically new: classical e-mail / attachment based sharing, sharing through web interfaces (through a Moodle frontend), and sharing through a VR interface provided by a recently developed VR engine called MaxWhere. To this end, the paper introduces new methods and a new set of concepts for the purposes of benchmarking digital capabilities and user effectiveness within the domain of workflow sharing. The paper applies these concepts and methods to compare the use of the above listed technologies with the participation of 379 test subjects. Tests show that the users were able to complete the required workflow at least 50% faster in the MaxWhere 3D environment than in all other competing cases. The paper also proves that 3D environments are capable of providing users with a much higher level of comprehension when it comes to sharing and interpreting digital workflows.
Keywords: VR-learning; e-learning; Cognitive Infocommunications
Abstract: The rapid evolution of information technology and of a new networked culture in the 21st Century has brought a new question to the forefront of scientific interest: the question of how new technologies influence the effectiveness with which humans are able to perform specific tasks. This paper presents an experiment contrasting traditional 2D interfaces and the MaxWhere 3D VR educational platform in order to shed light on how the effectiveness of various operations and workflows constituting the core of digital literacy has evolved in recent times. In order to draw specific conclusions, a new framework of concepts, qualitative and quantitative metrics and experimental procedures is proposed in the paper. The final goal of the proposed framework is to help evaluate the effectiveness of digital workflows. The results of the experiment, evaluated in terms of the proposed framework, point to the conclusion that when using MaxWhere instead of traditional 2D interfaces, users are able to accomplish the same digital workflows with 30% less user operations, and up to 80% less machine operations. Based on these results, the paper concludes that MaxWhere as an educational platform offers users a number of ways to accomplish tasks that would otherwise require extremely complicated digital workflows in more traditional 2D environments.
Abstract: 2D advertising in VR is more effective than in the classic banner ad format, our study confirms that ads in VR evoke better memory, namely more participants remembered the advertisement displayed in VR than the web-based ad. Advertising in virtual realities does not have to mean a virtual space exclusively dedicated to the promoted product. It can be a 2D ad inserted in the virtual space. It differs from the classic web-based ads, as it is not inserted in the content of a webpage, but stands alone in a virtual space. In this paper, we show a comparison of the classic banner ads, and 2D ads placed in a 3D virtual world. The effectiveness of the VR advertisement is higher than the classic web-based ads. In our experiment 22 people were involved. As the virtual space, we used the MaxWhere virtual platform, where the participant’s task was to read four online articles. In one condition four banner ads were placed on each webpage, in the other condition, the advertisement was placed in the virtual space. Then, they answered questions about the article and the advertisement.
Keywords: virtual reality; MaxWhere; advertisement; internet advertising; marketing
Abstract: The aim of this paper is to give an overview on virtual and remote laboratory systems and to evaluate current solutions focusing on feasibility and applicability in higher education. Based on the conclusions of this evaluation, a new set of requirements are established against a modern virtual laboratory system. Finally, an overview of state of the art infocommunication technologies, including cognitive infocommunication are presented, which can help create high user experience in the new virtual laboratory environment.
Keywords: virtual; laboratory; system; overview; design
Abstract: Nowadays it is increasingly visible that a change in the approach is needed in the field of education, thus we should move from “traditional” educational methods towards experience-oriented and cooperative teamwork-based education which considers the characteristics of the digital generation. After the brief demonstration of the methodological characteristics and the principles of digital culture, the present study aims to introduce how a lesson built on the improvement of different intelligence levels through cooperative techniques can be implemented with the help of virtual space, what opportunities are provided by the MaxWhere program for planning and organising teamwork and for supporting learning.
Keywords: cooperative learning; VR learning environment; MaxWhere; teaching methodology; digital culture; the improvement of intelligence areas; formative assessment; interactive learning-teaching
New technological advances of the 20th and 21st Centuries provide several new opportunities for engineers in the future. Modern engineering methods feasible by these new technical solutions, however, cannot meet expectations in all fields and situations without adequate knowledge and competence. Spreading new and modern engineering methods as well as acquiring new applications is a crucial issue in education. In brain research, which is one of the most significant research areas of the past decades, many new results and meters have appeared that could be used in engineering methods, too. Based on brain activity observation, new meters open up new horizons in engineering applications. Electroencephalogram-based brain activity observation processes are very promising and have been used in several engineering research primarily for implementation of control tasks. In this paper, an EEG-based engineering research work is demonstrated, which supports the acquirement of practical knowledge and can measure cognitive ability with a device capable of brain activity observation. In the engineering research task, a brain-computer interface (BCI) had to be developed for the measurement of the average level of attention. The results of the BCI have been compared and contrasted to the results of two tests applied in cognitive psychology, the PEBL Continuous Performance Test (pCPT) and the PEBL Test of Attentional Vigilance (pTOAV). It can be stated that the results of the procession developed in this research and the results of the pCPT and the pTOAV tests are in correlation.
Keywords: brain-computer interface; Continuous Performance Test; Test of Attentional Vigilance; electroencephalogram; PEBL
Brain research is one of the most significant research areas of the last decades, in which many developments and modern engineering technologies are applied. The electroencephalogram (EEG)-based brain activity observation processes are very promising and have been used in several engineering research fields. Objective: The main goal of this research was to develop a Brain-Computer Interface (BCI) system to observe the level of vigilance calculated by Think Gear-ASIC Module (TGAM1) technology and to evaluate the output with learning efficiency tests applied in cognitive neuroscience. Methods: The performance of the BCI system is evaluated in a comparative study. The BCI system was tested by thirty-two test subjects and the attention level output was compared by the Psychology Experiment Building Language’s (PEBL’s) Corsi block test (pCORSI) and PEBL’s Ebbinghaus procedure (pEBBINGHAUS) tasks. Results: Using the BCI, we have shown statistically significant results between the BCI and the conventional cognitive neuroscience tests. The correlation between the tests and the average attention of the BCI was slightly strong for pCORSI Total Score (r=.63, p<.01 (2-tailed) and slightly strong for pEBBINGHAUS Total Correct (r=-.71, p<.01 (2-tailed). The average level of attention measured by the BCI system during the pCORSI test was 49.00%, while in case of the pEBBINGHAUS test it was 52.41% on all samples. Conclusion: The developed BCI system has a significant correlation with pCORSI and pEBBINGHAUS cognitive neuroscience tests. The BCI system is capable of observing attentional vigilance continuously. Significance: The developed BCI system is applicable to observe vigilance level in real-time while the level of attention depends on activities.
Keywords: brain-computer interface; Corsi block; Ebbinghaus procedure; electroencephalogram; PEBL; learning efficiency