有限小批量定制生产伯努利三机器装配系统实时性能分析

通常适用于大批量制造生产系统的稳态分析在过去几十年得到了广泛研究.然而,当生产量较小(例如,定制化有限小批量生产运行)时,暂态在生产过程中可能起到主要作用,稳态分析将变得不再适用.近年来,对有限小批量生产条件下的串行生产线的研究已经有了一些初步成果.与此同时,装配系统,其最终产品往往需要两个或者多个组件,也广泛用于实践生产中.本文中,在有限小批量生产运行的三机装配系统框架下,假设系统具有有限缓冲区容量,并且使用伯努利机器可靠性模型,研究了此类系统的性能评价问题.具体来说,首先推导出评价系统性能的数学模型和解析公式.然后,提出一种基于分解的方法来近似系统实时性能.最后,所提出的算法的准确性通过仿真数值实验进行了验证并通过一个数值实例进行了展示.

基于吸收态马尔可夫链的智能无人车系统实时性能分析

随着人工智能技术的进步和人机物融合系统的发展,智能无人车系统成为了新一代人工智能研究的前沿。智能无人车系统根据车辆和环境数据进行实时决策以控制无人车运行,因而该系统具有较高的实时性能要求,对系统实时性的分析是保障系统安全可靠的方法之一。为了对智能无人车系统的实时性能进行分析,以智能无人车变道系统为例,首先使用MARTE模型对智能无人车变道系统进行建模,在系统设计早期就引入性能需求参数;然后,通过模型转换将MARTE模型转化为吸收态马尔可夫链;最后,利用吸收态马尔可夫链的相关理论和公式综合估算了智能无人车系统的实时性能指标,并针对影响整个系统实时性的关键模块进行了分析。实验结果表明,文中所提模型和分析方法可以较好地分析智能无人车系统的实时性能。分析发现系统中智能模块的准确率与响应时间相互制约,在不同的运行场景下需要找到二者之间的平衡点以获得更优的实时性能。

ProfiBus协议的实时性能参数分析

在详细探讨Profibus现场总线数据链路层(MAC)协议的基础上,采用随机Petri网方法对协议令牌循环时间和总线存取效率进行建模分析,着重就协议的实时性能给出了确定随机Petri网(DSPN)模型和性能指标计算方法,并结合实例进行了计算和结果比较.

Performance analysis model for real-time Ethernet-based computer numerical control system

In order to optimize the embedded system implementation for Ethernet-based computer numerical control （CNC） system, it is very necessary to establish the performance analysis model and further adopt the codesign method from the control, communication and computing perspectives. On the basis of analyzing real-time Ethemet, system architecture, time characteristic parameters of control-loop ere, a performance analysis model for real-time Ethemet-based CNC system was proposed, which is able to include the timing effects caused by the implementation platform in the simulation. The key for establishing the model is accomplished by designing the error analysis module and the controller nodes. Under the restraint of CPU resource and communication bandwidth, the experiment with a case study was conducted, and the results show that if the deadline miss ratio of data packets is 0.2%, then the percentage error is 1.105%. The proposed model can be used at several stages of CNC system development.

Performance Analysis of Robotic Arm Manipulators Control System under Multitasking Environment

This work is to observe the performance of PC based robot manipulator under general purpose （Windows）, Soft （Linux） and Hard （RT Linux） Real Time Operating Systems （OS）. The same open loop control system is observed in different operating systems with and without multitasking environment. The Data Acquisition （DAQ, PLC-812PG） card is used as a hardware interface. From the experiment, it could be seen that in the non real time operating system （Windows）, the delay of the control system is larger than the Soft Real Time OS （Linux）. Further, the authors observed the same control system under Hard Real Time OS （RT-Linux）. At this point, the experiment showed that the real time error （jitter） is minimum in RT-Linux OS than the both of the previous OS. It is because the RT-Linux OS kernel can set the priority level and the control system was given the highest priority. The same experiment was observed under multitasking environment and the comparison of delay was similar to the preceding evaluation.

Performance analysis of QoS routing protocol for WiMedia networks

Though the WiMedia supports higher data rates than other WPAN technologies,a WiMedia device cannot reach other devices that are separated from it by more than 10 m,which is the typical limited transmission range of the WiMedia protocol.In this work,we propose a multi-hop QoS routing protocol to enable WiMedia devices to transmit real-time data to devices that are located out of the transmission range.The proposed routing protocol is a hybrid algorithm,which mixes the table-driven and on-demand routing algorithms,searching one or more routes according to the number of hops to a destination device.WiMedia MAC is potentially capable of learning the existence of neighbor devices by using a beacon frame.By utilizing the neighbors' information,all devices can create routing entries for devices within 2-hops periodically.For devices beyond the 2-hop range,the newly designed on-demand routing algorithm is applied to multi-hop routing.If a routing entry for a destination device is not listed in the routing table,the source device sends a request packet to 2-hop range devices which could be found in the routing table.Since every device maintains routing entries for 2-hop range devices in the routing table,the request packet is replied in advance before its arrival at the destination device.Also,to decide the optimal route for a destination device,the number of medium access slots(MASs),received signal strength indicator(RSSI)and hop count are utilized to establish a QoS-enabled routing table.We perform ns-2 simulation to investigate the performance of the proposed routing protocol with AODV and DSDV.The simulation results show that the proposed protocol has better throughput and lower overhead than other protocols.