Integrated guidance and autopilot design for a chasing UAV via high-order sliding modes

Integrated guidance and control (IGC) approaches exploit the synergy between guidance and control designs. This study focuses on the integrated guidance and control (autopilot) design for a chasing Uninhabited Aerial Vehicle (UAV) against a target aircraft. A second-order sliding structure with a second-order sliding mode (SOSM) including a high-order sliding mode (HOSM) observer for the estimation of the uncertain sliding surfaces is selected to develop an integrated guidance and autopilot scheme. In order to make the design synthesis easier, intermediate control variables for partial derivatives of a sliding surface are carefully selected. The resulting sliding surface structure is simple and sufficient to relate the actuator input to the sliding surface. The potential of the proposed method is demonstrated through an aircraft application by comparing its simulation performance, number of tuning parameters used, and information needed for its implementation with an approach where the guidance law and the controller are designed separately.     

Developing mathematics teacher knowledge: the paradidactic infrastructure of “open lesson” in Japan

In this paper, we first present a theoretical approach to study mathematics teacher knowledge and the conditions for developing it, which is firmly rooted in a systemic approach to didactic phenomena at large, namely the anthropological theory of the didactic. Then, a case of open lesson is presented and analysed, using this theoretical approach, to show how the format of open lesson contributes to the construction and diffusion of didactic knowledge in the community of mathematics teachers in Japan. The basic idea of this format is that teachers from other schools are invited to observe a class taught by a teacher then participate in a discussion session with him on the details of the lesson. For the case study, we analyse the lesson plan prepared for an open lesson, the observed lesson and the teachers’ discussion. As a result, an open lesson session has been described as a specific form of post-didactic practice related directly to an actual observed lesson, and aiming specifically at elaborating the theoretical aspects of teacher’s didactic practice in the lesson and beyond it.     

Reading processes of English sentences in Japanese and Canadian students

Native skilled, non-native skilled, and non-native non-skilled English readers read English texts and their reading times of words were measured. The results showed that reading times of native skilled readers were independent from the word length, word location, and grammatical word classification compared to non-native readers. Reading times of nouns strongly correlated with reading skill of readers. Although non-native skilled readers comprehended text meanings well, however the pattern of reading time of words was still different from those of native reader.     

An Analysis of Primary School Dropout Patterns in Honduras

This study hypothesized that repeating a grade is one reason why Honduran primary students drop out of school but not the main reason. Using longitudinal data, we analyzed student enrollment patterns up until students left school. The results revealed that many students dropped out suddenly without having previously repeated a grade, although many dropouts had also repeated a grade at some point, and repeating a grade experience was not among the most frequently appearing dropout patterns in any of the completed grades. The findings indicated that low expectations of education and the need to enter the labor market were causes of immediate dropout.     

CAMELOT: collaborative and multimedia environment for learners on teams

In the business-systems-design learning environment, there may be more than one solution to any given problem. For instance, the data model will be different depending on each learner’s perspective. Accordingly, group learning systems are very effective in this domain. We have developed a collaborative and multimedia environment for learners on teams (CAMELOT) using the ‘nominal group technique’ for group problem solving. In this paper, the basic framework of the collaborative learning system and the effectiveness of collaborative learning in designing the data model are described. By using CAMELOT, each learner learns how to analyse through case studies and how to collaborate with his or her group in problem solving. Learners come to a deeper understanding from using CAMELOT than from studying independently because they can reach better solutions through discussion, tips from other learners and examination of one another’s individual works.     

Donald Super's Contribution to Career Guidance and Counselling in Japan

Dr Donald Super's contributions to career guidance and counselling in Japan are summarised within the framework of his career development theory from 1960 to 1990. The first part is related to the theoretical frame of reference of career guidance in the secondary school. The second is focused on developing a theoretical and practical basis for career counselling for the adult population. It is concluded that the importance of his approach has increased in the changing Japanese society.     

Modelling error distribution in the ground reaction force during an induced-acceleration analysis of running in rear-foot strikers

The objective of this study was to develop and evaluate a methodology for quantifying the contributions of modelling error terms, as well as individual joint torque, gravitational force and motion-dependent terms, to the generation of ground reaction force (GRF), whose true value can be measured with high accuracy using a force platform. Dynamic contributions to the GRF were derived from the combination of (1) the equations of motion for the individual segments, (2) the equations for constraint conditions arising from the connection of adjacent segments at joints, and (3) the equations for anatomical constraint axes at certain joints. The contribution of the error term was divided into four components caused by fluctuation of segment lengths, geometric variation in the constraint joint axes, and residual joint force and moment errors. The proposed methodology was applied to the running motion of thirteen rear-foot strikers at a constant speed of 3.3?m/s. Modelling errors arose primarily from fluctuations in support leg segment lengths and rapid movement of the virtual joint between the foot and ground during the first 20% of stance phase. The magnitudes of these error contributions to the vertical and anterior/posterior components of the GRF are presented alongside the non-error contributions, of which the joint torque term was the largest.     

The influence of audience and monetary reward on the putting kinematics of expert and novice golfers

We investigated changes in movement kinematics and attentional focus when expert and novice golfers performed a golf-putting task under pressure. Six male professional golfers and five male novice golfers performed 100 acquisition trials, followed by 10 trials in the pressure condition with a performance-contingent cash reward and small audience. After the 10 trials in the pressure condition, participants answered a questionnaire concerning attentional focus during both types of trial, including such aspects as conscious control of movements and the effects of distraction. A pressure manipulation check revealed a modest increase in physiological arousal, in that heart rate increased by about 10 bpm although state anxiety did not increase. A two-dimensional analysis of movement kinematics revealed that the amplitudes of arm and club movements decreased on the backswing in the pressure condition. Arm and club movement speed decreased on the foreswing in both experts and novices. Furthermore, neither experts nor novices changed their attentional focus in the pressure condition. Whereas previous studies of "choking under pressure" focused on attentional changes, the kinematic changes found in the present study were possibly caused by the influences of strategy modification and/or emotional response. Choking phenomena can be explained by attentional changes, along with the influences of strategy modification and/or emotional response under pressure.     

Aerodynamic properties of an archery arrow

Two support-interference-free measurements of aerodynamic forces exerted on an archery arrow (A/C/E; Easton Technical Products) are described. The first measurement is conducted in a wind tunnel with JAXA’s 60 cm Magnetic Suspension and Balance System, in which an arrow is suspended and balanced by magnetic force against gravity. The maximum wind velocity is 45 m/s, which is less than a typical velocity of an arrow (about 60 m/s) shot by an archer. The boundary layer of the arrow remains laminar in the measured Re number range (4.0 × 10³ < Re < 1.5 × 10⁴), and the drag coefficient is about 1.5 for Re > 1.0 × 10⁴. The second measurement is performed by a free flight experiment. Using two high-speed video cameras, we record the trajectory of an archery arrow and analyze its velocity decay rate, from which the drag coefficient is determined. In order to investigate Re number dependence of the drag coefficient in a wider range (9.0 × 10³ < Re < 2.4 × 10⁴), we have developed an arrow-shooting system using compressed air as a power source, which launches the A/C/E arrow at an arbitrary velocity up to 75 m/s. We attach two points (piles) of different type (streamlined and bullet) to the arrow-nose. The boundary layer is laminar for both points for Re less than about 1.2 × 10⁴. It becomes turbulent for Re larger than 1.2 × 10⁴ and the drag coefficient increases to about 2.6, when the bullet point is attached. In the same Re range, two values of drag coefficient are found for the streamlined point, of which the lower value is about 1.6 (laminar boundary layer) and the larger value is about 2.6 (turbulent boundary layer), confirming that the point-shape has a crucial influence on the laminar to turbulent transition of the boundary layer.