果蔬采摘机器人行走运动控制系统设计——基于磁导引

为实现果蔬采摘机器人作业时自主行走,研究采用磁导引技术和PID算法等实现对预定路径的跟踪。以磁导引传感器作为导航传感器,在果蔬采摘机器人平台上搭建转向控制机构,依据磁导引传感器工作特性,提出PID算法作为导引算法。根据导引传感器得到机器人当前位置相对于导引磁条的距离偏差,作为PID控制器的输入,将机器人前轮期望转角和车体期望速度作为输出,在Mat Lab中对算法进行圆曲线跟踪仿真。仿真结果表明:机器人可快速跟踪到预定路线,跟踪误差在±30 mm以内,直线段稳定状态误差在±5 mm以内。     

基于太阳能发电的小型农业物联网供电系统设计

农业物联网因工作环境和使用条件的限制,多分布于农业生产一线,导致供电问题一直以来是影响农业物联网高效推广的技术瓶颈。针对以上问题提出采用模块化设计方法,设计并研制一种基于太阳能发电的农业物联网多功能供电系统。系统设计了发电、储电、显示、保护和遥控等功能,可为用户提供直流5 V,12 V和交流220 V供电,还可根据实际需求增加自动逐日循迹、防盗报警等扩展功能。通过试验测量,在使用40 W光伏板、内部采用12 V、10 AH铅锌蓄电池容量作为供电电源,外部接12 V直流负载,在4 A放电电流条件下,全天24 h供电最低储电量为26%、最高为100%,充放电次数达到400次以上。实际产品具有体积小、成本低、模块化设计等特点,适合于农业物联网、无人值守数据采集终端等不便于连接外部电源等工作环境。     

双差速驱动移动机器人路径跟踪混合控制律研究

针对双差速驱动移动机器人的路径跟踪问题,建立了双输入-双输出的非线性运动学模型并进行了输入-输出线性化,分析了冗余运动约束的速度协同条件,提出了一种融合偏差智能转化评价函数法和指数稳定控制的混合控制律。评价函数法可针对不同的偏差状态智能选择合适的控制量以将其转化到指数稳定控制的适用范围,再通过指数稳定控制实现姿态角偏差和距离偏差向零的同步收敛。数字仿真和实验测试结果表明,该混合控制律可平滑转化偏差状态、同步消除位姿偏差,使移动机器人精确、稳定地跟踪直线和圆弧导引路径。     

基于微分几何的E-ECHPS车辆转向稳定性控制

为了提高装备电控液压助力转向系统(E-ECHPS)的车辆高速紧急转向稳定性,提出了基于微分几何的线性参考模型反馈跟踪控制策略;建立了包括整车动力学模型、轮胎模型、转向系统模型和ESC模型的非线性动力学模型,通过整车试验和台架试验验证了模型的正确性;推导了系统的仿射非线性状态方程,考虑到轮胎、液压系统和ESC的非线性,运用微分几何理论对系统进行精确线性化得到输入输出伪线性系统;建立了包含转向系统的线性参考模型,为了实现对线性参考模型理想状态的跟踪,构造了反馈跟踪控制器;以方向盘转矩为输入进行了有控制和无控制下的阶跃转向仿真和单移线仿真,结果表明:施加反馈跟踪控制可以显著提高车辆在高速紧急转向工况下的操纵稳定性,为E-ECHPS系统的控制策略设计提供了理论依据。     

基于Kinect骨骼跟踪技术的手势识别研究

为了实现自然方便的人机交互,提高用户体验,尝试引入微软公司的一款体感周边外设Kinect设备,利用Kinect传感器所获取的人体骨骼跟踪识别点,通过对双手在三维空间中的位置坐标转换,对缩放、旋转的手势进行匹配,将合法的手势信息转换为识别结果,反馈给系统并完成相应的控制指令输出,实现与系统的交互控制.结果表明,该系统具有较高的精度和稳定性,具有一定的借鉴意义.     

基于模块化2D-LDA的视频监控中的人脸识别算法

提出了一种基于扩展二维线性判别分析的人脸识别算法.通过扩充人脸样本,提高了人脸识别的性能.同时在视频监控的实际应用环境中进行了仿真,仿真结果表明,改进后的算法在性能和人脸识别精确度方面有了较大的提高.     

Dobutamine Stress Echocardiography for Assessment of Systolic Function in Dogs with Experimentally Induced Mitral Regurgitation

Background

Systolic dysfunction is associated with poor outcomes in dogs with myxomatous mitral valve disease. However, assessment of systolic variables by conventional echocardiographic methods is difficult in these dogs because of mitral regurgitation (MR).

Hypothesis

We hypothesized that assessment of systolic function by dobutamine stress may identify systolic dysfunction in dogs with MR, and that 2‐dimensional speckle‐tracking echocardiography (2D‐STE) could quantitatively evaluate myocardial function.

Animals

Anesthetized dogs with experimentally induced MR.

Methods

Dogs were examined for systolic myocardial deformations using 2D‐STE during dobutamine infusion before and 3 and 6 months after MR induction. We evaluated peak systolic rotation and rotation rate in each basal and apical view; peak systolic torsion and torsion rate were also calculated.

Results

Invasive peak positive first derivatives of left ventricular pressure (dp/dt) were significantly decreased in dogs 6 months after induction of MR compared with pre‐MR results. After 3 and 6 months of MR, dogs had diminished peak systolic torsion values and torsion rates in response to dobutamine infusion compared with pre‐MR results (3 months, P < .001 and P = .006; 6 months, P = .003 and P = .021). These results were significantly correlated with overall invasive dp/dt (r = 0.644, P < .001; r = 0.696, P < .001).

Conclusions and Clinical Importance

Decreased torsion during dobutamine infusion in dogs with MR may reflect latent systolic dysfunction. Dobutamine infusion, therefore, may be useful for the assessment of systolic function in dogs with MR.     

视日轨迹太阳跟踪装置控制系统设计

根据天文学上的天球模型,选择地平坐标系法的高度角和方位角来描述太阳位置,并将高度角和方位角的算法程序化,以此作为双轴太阳能跟踪装置的核心算法．采用STC89C52作为控制芯片,利用高精度时钟芯片DS12C887提供时间信息,同时引入风速传感器和压力传感器,使得控制系统能在恶劣条件下可实现自保护和除雪自清洁的功能．最后通过立杆投影法验证太阳能跟踪装置的跟踪效果．     

Upstream migration of chum salmon through a restored segment of the Shibetsu River

Abstract –  A segment of the Shibetsu River was restored to reconstruct the ecological condition of the previously canalized river stretch to a more natural, meandering state. In this study, we investigated the upstream migration of chum salmon ( Oncorhynchus keta ) using radio transmitters to track the horizontal position of fish and data loggers to detect the vertical swimming depth of fish, simultaneously. The monitored salmon travelled near the bottom of the water column and along the riverbanks, and tended to hold in deep, slow current areas in the canalized river. In the restored segment, the fish swam at more shallow depths and against stronger currents. Although the three tracked fish all reached the confluent point and chose to enter the restored segment, they did not remain in the segment for long. This indicates that the restored area facilitates the upward migration of the chum salmon.     

Movements and diving behaviour of white-chinned petrels: Diurnal variation and implications for bycatch mitigation

1. Many seabirds dive to forage, and the ability to use this hunting technique varies according to such factors as morphology, physiology, prey availability, and ambient light levels. Proficient divers are more able to seize sinking baits deployed by longline fishing vessels and may return them to the surface, increasing exposure of other species. Hence, diving ability has major implications for mitigating incidental mortality (bycatch) in fisheries.
2. Here, the diving behaviour and activity patterns of the most bycaught seabird species worldwide, the white-chinned petrel (Procellaria aequinoctialis), tracked from Bird Island (South Georgia), are analysed. Three data sources (dives, spatial movements, and immersion events) are combined to examine diverse aspects of at-sea foraging behaviour, and their implications for alternative approaches to bycatch mitigation are considered.
3. The tracked white-chinned petrels (n = 14) mostly performed shallow dives (<3 m deep) of very short duration (<5 s), predominantly during darkness, but only 7 and 10% of landings in daylight and darkness, respectively, involved diving, suggesting that surface-seizing is the preferred foraging technique. Nonetheless, individuals were able to dive to considerable depth (max = 14.5 m) and at speed (max = 2.0 m·s⁻¹), underlining the importance of using heavy line-weighting to maximize hook sink rates, and bird-scaring lines (Tori lines) that extend for long distances behind vessels to protect hooks until beyond diving depths.