Trajectory tracking for a quadrotor under wind perturbations: sliding mode control with state-dependent gains     

Gabriele Perozzi  Denis Efimov  Jean-Marc Biannic  Laurent Planckaert 《Journal of The Franklin Institute》2018,355(12):4809-4838

The problem of position tracking of a mini drone subject to wind perturbations is investigated. The solution is based on a detailed unmanned aerial vehicle (UAV) model, with aerodynamic coefficients and external disturbance components, which is introduced in order to better represent the impact of the wind field. Then, upper bounds of wind-induced disturbances are characterized, which allow a sliding mode control (SMC) technique to be applied with guaranteed convergence properties. The peculiarity of the considered case is that the disturbance upper bounds depend on the control amplitude itself (i.e. the system is nonlinear in control), which leads to a new procedure for the control tuning presented in the paper. The last part of the paper is dedicated to the analysis and reduction of chattering effects, as well as investigation of rotor dynamics issues. Conventional SMC with constant gains, proposed first order SMC, and proposed quasi-continuous SMC are compared. Nonlinear UAV simulator, validated through in-door experiments, is used to demonstrate the effectiveness of the proposed controls.  相似文献   

Perpetual Beginnings: The Role of Phenomenological Hermeneutics in Art Education     

Gabriele Esser-Hall 《The International Journal of Art & Design Education》2000,19(3):288-296

This paper reflects on the role of phenomenological hermeneutics as part of art history and theory programmes in art education. Though initially confined to Philosophy, this branch of hermeneutics can be utilised in Art Education also, as concepts explored here such as the appropriation of knowledge, interpretation, reading and understanding offer an effective tool to investigate the strength and potential of subjectivity, metaphoricity and embodiment in art practice. This paper begins with a reflection on the most effective space where theory teaching can take place and offers the concept of the hermeneutical space, where teaching is inclusive and supportive of self determined contributions to processes of theoretical reflection on art practice. A mutual learning experience is fostered in this environment, where teacher and student respect each other's readings. Finally, I put forward suggestions as to how this can be realised in an actual teaching situation by relating my own experience.  相似文献   

Autonomy enhances running efficiency     

Takehiro Iwatsuki  James W. Navalta  Gabriele Wulf 《Journal of sports sciences》2019,37(6):685-691

Performer autonomy has been shown to contribute to effective motor performance and learning. Autonomy support is therefore a key factor in the OPTIMAL theory of motor learning (Wulf, G., & Lewthwaite, 2016). The purpose of the present study was to examine whether supporting individuals’ need for autonomy by giving them choices would increase movement efficiency. Such a finding would be consistent with the OPTIMAL theory prediction that autonomy facilitates the coupling of goals and actions. Participants (N = 32) were asked to run at a submaximal intensity (65% of VO₂ max) for 20 minutes. Before the run, participants in a choice group were able to choose 5 of 10 photos as well as the order in which they would be shown to them on a computer screen during the run. Control group participants were shown the same photos, in the same order, chosen by their counterparts in the choice group. Throughout the run, oxygen consumption and heart rate were significantly lower in the choice group than the control group. Thus, providing autonomy support resulted in enhanced running efficiency. The present findings are in line with the notion that autonomy facilitates goal-action coupling.  相似文献   

Enhanced expectancies improve movement efficiency in runners     

Stoate I  Wulf G  Lewthwaite R 《Journal of sports sciences》2012,30(8):815-823

We followed up on recent findings demonstrating that enhancing performers' expectancies can improve their performance. Specifically, we examined whether providing experienced runners with positive feedback regarding their movement efficiency would increase running efficiency. Two groups of experienced runners ran on a treadmill at 75% of their maximum oxygen consumption (VO(2max)) for 10 min. One group (enhanced expectancy) was provided with (fabricated) feedback about the efficiency of their running style every 2 min. A control group was not given feedback. Oxygen consumption decreased in the enhanced expectancy group across measurement times (every 2 min for 10 min), but remained the same in the control group. In addition, performance perceptions changed only in the enhanced expectancy group, indicating a perception of greater ease of running and reduced fatigue when assessed after compared with before running. Finally, positive affect increased from a pre- to a post-test in the enhanced expectancy group, in contrast to the control group. Our findings show that enhanced expectancies can have a positive effect on movement efficiency and running experience. They add to the accumulating evidence for the social-cognitive-affective-motor nature of motor performance.  相似文献   

Feedback about more accurate versus less accurate trials: differential effects on self-confidence and activation     

Badami R  VaezMousavi M  Wulf G  Namazizadeh M 《Research quarterly for exercise and sport》2012,83(2):196-203

One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected byfeedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On day 1, participants performed a golf putting task under one of two conditions: one group received feedback on the most accurate trials, whereas another group received feedback on the least accurate trials. On day 2, participants completed an anxiety questionnaire and performed a retention test. Shin conductance level, as a measure of arousal, was determined. The results indicated that feedback about more accurate trials resulted in more effective learning as well as increased self-confidence. Also, activation was a predictor of performance.  相似文献   

Computer Self-Efficacy and Motivation to Learn in a Self-Directed Online Course     

Marcia J. Simmering  Clay Posey  Gabriele Piccoli 《Decision Sciences Journal of Innovative Education》2009,7(1):99-121

Despite the increased use of new learning technologies, there is still much to be learned about the role of learner characteristics in online learning. The purpose of this study was to examine how subjects' characteristics normally associated with effective training (i.e., initial motivation to learn and self-efficacy) related to learning in a self-directed online course. From an analysis of 190 respondents, computer and Internet usage prior to the start of class were positively related to individuals' computer self-efficacy and computer self-efficacy was positively related to learning. However, contrary to expectations, computer self-efficacy was not related to initial motivation to learn and motivation to learn was not related to learning in the class. Post hoc analysis of qualitative data enabled a rich explanation of the findings, including an evaluation of the unexpected relationships among the variables of interest and the nature of self-directed courses in virtual learning environments.  相似文献   

Dealing with errors in mathematics classrooms: Structure and relevance of perceived error climate     

Gabriele Steuer  Gisela Rosentritt-Brunn  Markus Dresel 《Contemporary educational psychology》2013

Errors are often perceived by students as self-threatening and not as learning opportunities. The present work focuses on contextual influences on reactions to errors and learning processes. Based on prior research, a conceptualization of perceived error climate in the classroom with eight subdimensions and one superordinate uniform factor is proposed and a newly developed student questionnaire for its assessment is presented. Results of a study with N = 1116 students from 56 mathematics classrooms in German secondary schools indicated the validity of the error climate conceptualization and the suitability of the questionnaire. Moreover, the results showed that perceived error climate in the classroom predicted the adaptivity of students’ individual reactions to errors above and beyond perceived classroom goal structures and personal achievement motivation (academic self-concept, mastery goal orientation). In addition, the study provided evidence that perceived error climate affects – partially mediated through students’ individual reactions to errors – the quantity and self-regulation of students’ effort.  相似文献   

The teacher work sample: A tool for scaffolding and assessing preservice teachers' early field experiences     

John E. Henning  Andrea DeBruin‐Parecki  Becky Wilson Hawbaker  Curtis P. Nielsen  Elana Joram  Anthony J. Gabriele 《The Teacher Educator》2013,48(3):188-207

Abstract

This article describes adapting teacher work sample methodology from the student teaching level to a 4‐week, 25‐hour field experience occurring relatively early in a teacher education program. The goals of the project were twofold: (a) to examine whether an adapted version of the teacher work sample would promote planning and reflection in preservice teachers, and (b) to explore the potential of an adapted teacher work sample as an assessment tool. Adaptations to the original, such as emphasizing formative over summative assessment, are briefly described. Survey and focus group data from a pilot combined with survey data from a semester of full implementation with 270 teacher candidates indicate the teacher work sample is useful for promoting reflection and an understanding of student assessment. The advantages of the teacher work sample are maximized when teacher candidates are engaged in whole class instruction.  相似文献   

The influence of situational emotions on the intention for sustainable consumer behaviour in a student-centred intervention     

Gabriele Fröhlich  Daniela Sellmann  Franz X. Bogner 《Environmental Education Research》2013,19(6):747-764

Within the curriculum guidelines for Bavaria, we designed a hands-on educational programme for teaching sustainability with regard to agriculture, food and consumerism, partly implemented on a farm as an out-of-school learning setting. The participants were fifth graders (N?=?176). The research followed a quasi-experimental design and used the subscale consumerism of the General Ecological Behaviour Scale and situational emotions (interest, well-being, boredom) to focus data collection activities. The study monitored the students’ knowledge increase and their Inclusion of Nature in Self (INS) scores as possible influencing factors on environmental behaviour. After participation in the programme, while we found that the students intended to consume in more environmentally friendlier ways, this intention did not persistent over a seven-week time span, nor did it relate to the INS or knowledge scores. There was, however, a high correlation with positive situational emotions like interest (r?=?.46, p???.001) and well-being (r?=?.39, p???.001), and a negative correlation with boredom (r?=??.42, p???.001). We conclude that the ‘effect’ of the programme immediately measured after the intervention was strongly linked to situational (short-term) emotions, and should be considered in educational planning as well as the evaluation of sustainability teaching and learning.  相似文献   

Promoting connectedness with nature through environmental education     

Anne K. Liefländer  Gabriele Fröhlich  Franz X. Bogner  P. Wesley Schultz 《Environmental Education Research》2013,19(3):370-384

It has been suggested that a positive human–nature relationship is essential for countering today’s environmental problems. Prior environmental education research has focused largely on knowledge or attitudinal outcomes, and few studies have examined the ability of environmental education programmes to promote connectedness with nature. Therefore, our goal was to (1) examine differences in connectedness with nature among a sample of children with differing ages and academic tracks, and (2) investigate whether environmental education can help promote and sustain connectedness with nature. With a pre-, post- and retention test design, we assessed a comprehensive four-day environmental education programme on water at a school field centre, using the inclusion of nature in self (INS) scale to identify the change in connectedness of 9–10-year-old pupils and 11–13-year-old pupils. We found that younger children and university-track pupils had higher INS scores than older children and general-education-track pupils, respectively. Participating in environmental education resulted in a robust short-term increase in connectedness with nature in both age groups. However, only the younger pupils’ connectedness remained sustained four weeks following the treatment. Environmental educators should keep in mind that strengthening connectedness to nature is more sustainable before the age of 11.  相似文献