球型摄像机高速运动控制驱动策略的SoC实现方案—系统综合篇

作者描述了作为高速球形摄像机运动控制系统主要执行元件—步进电机微步驱动控制的SoC实现方案。报告应用基于模型的分析描述以及基于步进电机特性的物理分析结果,设计了一种在单芯片（SoC,System On Chip）上实现的新型高速球形摄像机运动控制的电子系统级方案。该方案针对步进电机高精度微步驱动控制设计需求,建立了运动控制电子系统微步驱动策略各个设计层次上的模型,通过仿真探索其系统架构及性能优化。这篇文章也是《单芯片实现高速摄像机运动控制系统的一种设计方案—（系统分析篇）》的续篇—系统综合篇。     

基于单片机直流电机控制系统设计

本文设计了以单片机AT89S52为控制核心,以L298作为驱动的PWM直流调速系统。系统采用数字PID控制算法,实现了转速的闭环控制。系统可通过键盘设定电机的状态和期望转速,同时实时数码显示转速。     

Interaction between orthographic and graphomotor constraints in learning to write

We investigated the combined effects of orthographic and graphomotor constraints as a function of handwriting proficiency in children. Twenty-four first graders, 20 third graders, and 21 fifth graders wrote single five-letter words in cursive writing on a sheet of paper affixed to a digitizing tablet. The words were chosen according to two orthographic constraints, namely their lexical frequency and the graphemic complexity of the last three letters, and one graphomotor constraint resulting from the motor difficulty of tracing the first letter. In addition to massive improvements of handwriting with grade, the results revealed, in the youngest group only, an interaction between first-letter difficulty and lexical frequency. This finding suggests that, before handwriting movement becomes automated, the cognitive resources needed for retrieving word spelling interferes with motor processing while writing a difficult letter. When students start learning to write, they are particularly sensitive to the combination of orthographic and graphomotor constraints.     

Theory and practice in sport psychology and motor behaviour needs to be constrained by integrative modelling of brain and behaviour

Because of advances in technology, the non-invasive study of the human brain has enhanced the knowledge base within the neurosciences, resulting in an increased impact on the psychological study of human behaviour. We argue that application of this knowledge base should be considered in theoretical modelling within sport psychology and motor behaviour alongside existing ideas. We propose that interventions founded on current theoretical and empirical understanding in both psychology and the neurosciences may ultimately lead to greater benefits for athletes during practice and performance. As vehicles for exploring the arguments of a greater integration of psychology and neurosciences research, imagery and perception–action within the sport psychology and motor behaviour domains will serve as exemplars. Current neuroscience evidence will be discussed in relation to theoretical developments; the implications for sport scientists will be considered.     

PART VII: PSYCHOLOGY AND MOTOR CONTROL

The main aim of this study was to examine the age- and sex-associated variation in neuromuscular capacities of young distance runners. A secondary aim was to compare the magnitude of sex differences in young athletes in the same sport compared with the general population. Twenty-seven male and 27 female distance runners were enrolled in the study, whose ages ranged from 8.0 to 15.1 years at initial visit. Twenty males and 16 females were followed at approximate annual intervals for 4 or 5 years. Seven neuromuscular capacities were measured: quadrant jump, figure 8 run, standing long jump, vertical jump, flexed arm hang, sit-and-reach and sit-up. Age- and sex-associated variation was analysed by two-way analysis of variance. There were significant main effects for age for quadrant jump, figure 8 run, long jump, vertical jump, sit-and-reach and sit-up. There were significant main effects for sex for figure 8 run, long jump, vertical jump, flexed arm hang and sit-and-reach. The interaction between age and sex was statistically significant for long jump and vertical jump. In general, differences in neuromuscular agility (figure 8 run, quadrant jump) and explosiveness-power (long jump, vertical jump) between the sexes were attenuated before 13 years of age in young distance runners. However, during the adolescent growth spurt, differences in agility and power between the sexes emerged as a result of a continued increase in males and a plateau in females. Differences between the sexes in upper body neuromuscular endurance (flexed arm hang) and sit-and-reach persisted throughout the age range. The magnitude of sex differences between the runners and the general population varied by age and neuromuscular capacity.     

Objectively measured physical activity and psychosocial functioning in young children: The GECKO Drenthe cohort

ABSTRACT

The global trend in inactivity in children may be related to psychosocial problems. We investigated the cross-sectional association between physical activity (PA) levels and psychosocial functioning in 3.4–7.3-year-old children. Children from the Dutch GECKO birth cohort (N = 898; 51.6% boys) had PA levels assessed objectively by accelerometry (ActiGraph GT3X) for at least three days. Linear regression analysis was used for associations with psychosocial functioning (parent report of the Strengths and Difficulties Questionnaire), controlling for gender, age and socio-economic status. Higher total and moderate-to-vigorous PA levels (MVPA) were associated with higher Total Difficulty scores, and sedentary time to lower Total Difficulty scores. More time spent in MVPA was significantly associated to “hyperactivity/inattention” in both boys (Standardized B_BOYS = 0.192) and girls (Std.B_GIRLS = 0.139) whereas for the time in sedentary behaviour, a reverse association was found only in boys (Std.B_BOYS = ?0.230). In boys only, more time in MVPA (Std.B_BOYS = 0.154) and less time in sedentary behaviour (Std.B_BOYS = ?0.147), were significant determinants for ‘behavioural problems’. When using objectively measured PA, parents report more hyperactivity/inattention and behavioural problems in the more active children, and less in the more sedentary children, most clearly for boys. High levels of PA might be an indicator of psychosocial problems in young children.     

Cognitive to physical performance: a conceptual model for the role of motor simulation in performance

ABSTRACT

Motor simulation (MS) interventions incorporating motor imagery (MI), and more recently action observation (AO), are readily accepted as effective interventions to enhance motor skill performance. Existing models in the MS literature fail to consider the entire spectrum of MS interventions, focusing on MI or AO alone. This paper examines the theoretical basis and current understanding of MS efficacy, and introduces a novel, conceptual, Motor Simulation and Performance Model (MSPM) representing the performance improvements predicted to be associated with engaging with MS across expertise levels. The MSPM also outlines the multiple factors which regulate the efficacy of MS interventions. Based on the available evidence, the model suggests that MI will have a greater relative effect on performance as expertise increases, AO will have a greater effect in low skilled compared to high skilled performers, and that combined AO and MI (AO?+?MI) will be more effective than either MI or AO in isolation. The MSPM also depicts the additive effect of physical practice in conjunction with MS interventions. The MSPM represents for the first time the relative effects of various methods of motor learning based on evidence provided by the existing literature. It also highlights areas of research requiring further attention.     

Longitudinal associations between motor competence and different physical activity intensities: LabMed physical activity study

An appropriated level of motor competence is essential for children´s healthy growth and development and a key factor in the promotion of lifelong active lifestyles and health.

The purpose of this study was to examine associations between motor competence and different physical activity intensities (light, moderate, moderate-to-vigorous and vigorous physical activity), as well as total physical activity, over a two-year period, in adolescents. The sample comprised of 103 adolescents (13.49 ± 0.87 years, 53 girls), from the north of Portugal. Motor competence was evaluated with the body coordination test, Körperkoordination-Test-für-Kinder. Physical activity was objectively assessed with GT1M accelerometers (ActiGraph, Pensacola, FL, USA). Physical activity variables were expressed as proportions of accelerometer wear time. Regression analyses showed positive longitudinal associations between motor competence at baseline and moderate physical activity (B = 0.0033, p = 0.018), moderate-to-vigorous physical activity (B = 0.0052, p = 0.024) and total physical activity (B = 0.067, p = 0.040) at follow up, after adjustments for age, sex, the corresponding physical activity intensity at baseline, body mass index, pubertal stage and socioeconomic status. Our ?ndings highlight the importance of motor competence development to promote moderate-to-vigorous physical activity during adolescence.