A general model for cyclic machine scheduling problems

A general framework for modeling and solving cyclic scheduling problems is presented. The objective is to minimize the cycle time. The model covers different cyclic versions of the job-shop problem found in the literature, robotic cell problems, the single hoist scheduling problem and tool transportation between the machines.It is shown that all these problems can be formulated as mixed integer linear programs which have a common structure. Small instances are solved with CPLEX. For larger instances tabu search procedures have been developed. The main ideas of these methods are indicated.     

An optimization-based heuristic for the robotic cell problem

This study investigates an optimization-based heuristic for the robotic cell problem. This problem arises in automated cells and is a complex flow shop problem with a single transportation robot and a blocking constraint. We propose an approximate decomposition algorithm. The proposed approach breaks the problem into two scheduling problems that are solved sequentially: a flow shop problem with additional constraints (blocking and transportation times) and a single machine problem with precedence constraints, time lags, and setup times. For each of these problems, we propose an exact branch-and-bound algorithm. Also, we describe a genetic algorithm that includes, as a mutation operator, a local search procedure. We report the results of a computational study that provides evidence that the proposed optimization-based approach delivers high-quality solutions and consistently outperforms the genetic algorithm. However, the genetic algorithm delivers reasonably good solutions while requiring significantly shorter CPU times.     

An automated vane shear test tool for environmental monitoring with unmanned ground vehicles

The present work describes the development of a novel robotic vane shear test tool for characterization of soil parameters with high precision and accuracy. The tool automates industrial standards for testing procedures. The proposed system is capable of performing high resolution torque measurements, which are then used to estimate the shear strength of the soil. The design of the instrument and its advantages over traditional manual instruments are discussed, after which error sources, calibration, and test procedures are described. The developed tool was successfully validated against high-end commercial equipment. The built unit was employed for characterizing mine waste in a laboratory setting and also deployed in the field on board an Unmanned Ground Vehicle for remote soil characterization.     

Biomimetic flexible plate actuators are faster and more efficient with a passive attachment

Using three-dimensional computer simulations, we probe biomimetic free swimming of an internally actuated flexible plate in the regime near the first natural frequency. The plate is driven by an oscillating internal moment approx-imating the actuation mechanism of a piezoelectric macro fiber composite (MFC) bimorph. We show in our simulations that the addition of a passive attachment increases both swim-ming velocity and efficiency. Specifically, if the active and passive sections are of similar size, the overall performance is the best. We determine that this optimum is a result of two competing factors. If the passive section is too large, then the actuated portion is unable to generate substantial deflection to create sufficient thrust. On the other hand, a large actu-ated section leads to a bending pattern that is inefficient at generating thrust especially at higher frequencies.     

Transoral Robotic Surgery (TORS): Glottic Microsurgery in a Canine Model

OBJECTIVES/HYPOTHESIS: We hypothesize that bimanual, three-dimensional robotic surgery will prove valuable for glottic microsurgical procedures. STUDY DESIGN: To test this hypothesis, we developed and optimized a canine model for glottic microsurgery using a commercially available surgical robot. Methods Using a da Vinci Surgical Robot (Intuitive Surgical, Inc., Sunnyvale, CA), glottic microsurgery was performed with a hydrodissection technique in a canine model. The experiments were performed on two orotracheal intubated mongrel dogs under general anesthesia in the supine position on a standard operating room table. A videoscope and two, 360-degree rotating, 5- and 8-mm, wrested-end effector instruments were introduced transorally with three robotic arms. The surgeon performed the actual procedures while positioned at a robotic system console that was located across the operating room suite. The procedure was performed in duplicate and was documented with still and video photography. RESULTS: Glottic microsurgery was successfully performed using the da Vinci Surgical Robot, with both 5- and 8-mm instrumentation. The smaller, 5-mm instruments afforded greater visualization of the operative site and increased maneuverability, which resulted in reduced operative time. The robotic system provided excellent visualization as well as controlled and delicate microdissection at the vocal cord level. CONCLUSIONS: Robotic laryngeal microsurgery is technically feasible in the canine model and warrants consideration for evaluation in controlled human trials.     

海洋大气气溶胶光学模型参数的相关性研究

气溶胶光学模型参数在气溶胶遥感和气候强迫研究中都具有重要的作用.通过对全球近90个气溶胶自动观测网(AERONET)的海洋站点数据进行筛选、分类和分析,发现了气溶胶模型的中值半径及其标准偏差间的负相关性,并给出了经验关系.利用该关系对现行中分辩率成像光谱仪(MODIS)海洋气溶胶模型进行了评估,并指出了该模型存在的不足...     

移动机器人履行系统配置优化研究——基于闭排队网络理论

本文对移动机器人履行系统中货架调度任务的履行过程进行分析,根据机器人在货架装载、搬运、拣选、卸载四个过程的作业特点建立闭排队网络模型。采用近似平均值分析算法求解,实现系统绩效的迅速评估。通过与仿真计算实验的对比证明,模型对系统绩效的评估误差不超过5%。利用闭排队网络模型评估拣选台、机器人利用率和调度任务履行能力,实现对系统设施配置的讨论和优化。研究表明,拣选台均匀分布于仓库较长的两侧能提高系统履行绩效;系统存在最优机器人投放数量使系统整体利用率较高。