Bio-inspired magnetic helical microrobots have great potential for biomedical and micromanipulation applications. Precise interaction with objects in liquid environments is an important prerequisite and challenge for ...Bio-inspired magnetic helical microrobots have great potential for biomedical and micromanipulation applications. Precise interaction with objects in liquid environments is an important prerequisite and challenge for helical microrobots to perform various tasks. In this study, an automatic control method is proposed to realize the axial docking of helical microrobots with arbitrarily placed cylindrical objects in liquid environments. The docking process is divided into ascent, approach, alignment, and insertion stages. First, a 3D docking path is planned according to the positions and orientations of the microrobot and the target object. Second, a steering-based 3D path-following controller guides the helical microrobot to rise away from the container bottom and approach the target along the path. Third, based on path design with gravity compensation and steering output limits, alignment of position and orientation can be accomplished simultaneously. Finally, the helical microrobot completes the docking under the rotating magnetic field along the target orientation. Experiments verified the automatic docking of the helical microrobot with static targets, including connecting with micro-shafts and inserting into micro-tubes. The object grasping of a reconfigurable helical microrobot aided by 3D automatic docking was also demonstrated. This method enables precise docking of helical microrobots with objects, which might be used for capture and sampling, in vivo navigation control, and functional assembly of microrobots.展开更多
2017年8月甘肃陇南出现暴雨天气,礼县、武都气象站24 h降水量突破历史极值,极端性和局地性突出。应用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第5代全球大气再分析产品ERA5、雷达资料及地面加...2017年8月甘肃陇南出现暴雨天气,礼县、武都气象站24 h降水量突破历史极值,极端性和局地性突出。应用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第5代全球大气再分析产品ERA5、雷达资料及地面加密观测资料,对2017年8月6—7日、19—20日发生在甘肃省陇南地区的2次暴雨过程进行对比分析,重点讨论2次过程的环流背景以及强降水时段雷达反射率因子、径向速度、物理量特征。结果表明,2次暴雨过程均发生在西风槽偏北气流与中低层偏南暖湿气流交汇处,但是2次过程的主要影响系统及触发条件不同;雷达回波显示8月6—7日由冷式切变线引起的暴雨系统对流性较强,反射率因子值较高、中心高度较低,降水率较大,持续时间短;19—20日暖区降水的反射率因子值较低、中心高度较高,降水率较小,持续时间较长。展开更多
干旱地区极端降水事件往往会造成巨大的人员伤亡和经济损失,研究其演变特征及成因有利于提升该类天气的预报准确率。2022年8月13日西北干旱区甘肃省金塔县出现暴雨天气,日降水量和小时降水量均突破河西走廊国家级气象站历史极值,极端性...干旱地区极端降水事件往往会造成巨大的人员伤亡和经济损失,研究其演变特征及成因有利于提升该类天气的预报准确率。2022年8月13日西北干旱区甘肃省金塔县出现暴雨天气,日降水量和小时降水量均突破河西走廊国家级气象站历史极值,极端性、局地性特征显著。利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第5代全球大气再分析产品ERA5和实况观测资料对其成因进行分析。结果表明:暴雨出现在稳定的南亚高压北侧,对流层中、高层动力强迫较弱,斜压系统主要位于低层,为500 hPa短波槽前的低层切变线和地面冷锋;青藏高原热低压外围的低层水汽持续输送,形成了暴雨区局地性的极端水汽条件和中等强度的层结不稳定;地面冷锋前部,酒泉中东部低层水汽输送的区域差异形成了明显的湿度锋区和干线;造成极端短时强降水的中-γ尺度对流系统由干线触发,在冷锋和干线的交叉点处发展为导致极端暴雨的深厚湿对流,干线对流单体发展到深厚湿对流过程具有显著局地性特征。展开更多
基金supported by the National Natural Science Foundation of China(No.62273117)Pre-research Task(No.SKLRS202418B)of State Key Laboratory of Robotics and Systems(HIT).
文摘Bio-inspired magnetic helical microrobots have great potential for biomedical and micromanipulation applications. Precise interaction with objects in liquid environments is an important prerequisite and challenge for helical microrobots to perform various tasks. In this study, an automatic control method is proposed to realize the axial docking of helical microrobots with arbitrarily placed cylindrical objects in liquid environments. The docking process is divided into ascent, approach, alignment, and insertion stages. First, a 3D docking path is planned according to the positions and orientations of the microrobot and the target object. Second, a steering-based 3D path-following controller guides the helical microrobot to rise away from the container bottom and approach the target along the path. Third, based on path design with gravity compensation and steering output limits, alignment of position and orientation can be accomplished simultaneously. Finally, the helical microrobot completes the docking under the rotating magnetic field along the target orientation. Experiments verified the automatic docking of the helical microrobot with static targets, including connecting with micro-shafts and inserting into micro-tubes. The object grasping of a reconfigurable helical microrobot aided by 3D automatic docking was also demonstrated. This method enables precise docking of helical microrobots with objects, which might be used for capture and sampling, in vivo navigation control, and functional assembly of microrobots.
文摘2017年8月甘肃陇南出现暴雨天气,礼县、武都气象站24 h降水量突破历史极值,极端性和局地性突出。应用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第5代全球大气再分析产品ERA5、雷达资料及地面加密观测资料,对2017年8月6—7日、19—20日发生在甘肃省陇南地区的2次暴雨过程进行对比分析,重点讨论2次过程的环流背景以及强降水时段雷达反射率因子、径向速度、物理量特征。结果表明,2次暴雨过程均发生在西风槽偏北气流与中低层偏南暖湿气流交汇处,但是2次过程的主要影响系统及触发条件不同;雷达回波显示8月6—7日由冷式切变线引起的暴雨系统对流性较强,反射率因子值较高、中心高度较低,降水率较大,持续时间短;19—20日暖区降水的反射率因子值较低、中心高度较高,降水率较小,持续时间较长。
文摘干旱地区极端降水事件往往会造成巨大的人员伤亡和经济损失,研究其演变特征及成因有利于提升该类天气的预报准确率。2022年8月13日西北干旱区甘肃省金塔县出现暴雨天气,日降水量和小时降水量均突破河西走廊国家级气象站历史极值,极端性、局地性特征显著。利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第5代全球大气再分析产品ERA5和实况观测资料对其成因进行分析。结果表明:暴雨出现在稳定的南亚高压北侧,对流层中、高层动力强迫较弱,斜压系统主要位于低层,为500 hPa短波槽前的低层切变线和地面冷锋;青藏高原热低压外围的低层水汽持续输送,形成了暴雨区局地性的极端水汽条件和中等强度的层结不稳定;地面冷锋前部,酒泉中东部低层水汽输送的区域差异形成了明显的湿度锋区和干线;造成极端短时强降水的中-γ尺度对流系统由干线触发,在冷锋和干线的交叉点处发展为导致极端暴雨的深厚湿对流,干线对流单体发展到深厚湿对流过程具有显著局地性特征。
