基于VHDL语言的可编程逻辑系统的设计方法

提出一种基于VHDL语言的可编程逻辑系统的设计方法。阐述了可编程逻辑器件和VHDL语言的特点,说明了采用VHDL语言和可编程逻辑器件进行数字系统设计的有效性,并给出设计步骤。VHDL语言和可编程逻辑器件的结合作为一种强有力的设计方式,将为设计者的产品上市带来创纪录的速度。

LOGIC STRUCTURE OF PROGRAMMABLE INSTRUCTIONS FOR JAVA PROCESSORS

There are varieties of embedded systems in the world. It is a big challenge to optimize the instruction sets of System on Chips (SoCs) according to different systems' working environments. The idea of programmable instruction set is an effective method to gain embedded system's re-configurability. This letter presents a logic module for Java processor to be capable of using programmable instruction set. Cost (area, power, and timing) of the module is trivial. Such module is also reusable for other embedded system solutions besides Java systems.

Gas pipeline explosion resistance technology

Based on the features and requirements of gas drainage system, an optimized explosion resistance technology is done after a comprehensive analysis and research about the triple IR （Infrared Ray） flame detection technology, explosion resistance valve technology and explosion resistance control technology. An intelligent PLC （Programmable Logic Controller） resistance control system is designed which can cut offthe gas branch quickly and accurately, and the controller have automatic pressure maintaining function, valve rotation limit function, remote and local control interlock function. The reliability and rationality of explosion resistance technology is verified by gas pipeline explosion propagation and resistance simulation test. Overall response time of explosion resistance system is less than 100ms, and the spread of fire in gas pipeline can be prevented effectively.

Computer Controlled High Precise, High Voltage Pules Generator

High precise, high voltage pulse generator made up of high-power IGBT and pulse transformers controlled by a computer are described. A simple main circuit topology employed in this pulse generator can reduce the cost meanwhile it still meets special requirements for pulsed electric fields (PEFs) in food process. The pulse generator utilizes a complex programmable logic device (CPLD) to generate trigger signals. Pulse-frequency, pulse-width and pulse-number are controlled via RS232 bus by a computer. The high voltage pulse generator well suits to the application for fluid food non-thermal effect in pulsed electric fields, for it can increase and decrease by the step length 1.

Study on Position Control System with Programmable Logic Controller

To solve the problems of mechanical cam, tracking in an automatic welding machine, a new method of programmable logic controller ( PLC) tracking is presented. Based on analyzing the forming of welding tracking, a mathematical model of position control is set up. The experiments show that using a modified machine, PLC makes little welding positional error and can meet the product requirements.

Fully Integrated Machine Control for Ultra Precision Machining

To meet the demands for highly advanced components with ultra precise contour accuracy and optical surface quality arising in the fields of photonics and optics, automotive, medical applications and biotechnology, consumer electronics and renewable energy, more advanced production machines and processes have to be developed. As the complexity of machine tools rises steadily, the automation of manufacture increases rapidly, processes become more integrated and cycle times have to be reduced significantly, challenges of engineering efficient machine tools with respect to these demands expand every day. Especially the manufacture of freeform geometries with non-continuous and asymmetric surfaces requires advanced diamond machining strategies involving highly dynamic axes movements with a high bandwidth and position accuracy. Ultra precision lathes additionally equipped with Slow Tool and Fast Tool systems can be regarded as state-of-the-art machines achieving the objectives of high quality optical components. The mechanical design of such ultra precision machine tools as well as the mechanical integration of additional highly dynamic axes are very well understood today. In contrast to that, neither advanced control strategies for ultra precision machining nor the control integration of additional Fast Tool systems have been sufficiently developed yet. Considering a complex machine setup as a mechatronic system, it becomes obvious that enhancements to further increase the achievable form accuracy and surface quality and at the same time decrease cycle times and error sensitivity can only be accomplished by innovative, integrated control systems. At the Fraunhofer Institute for Production Technology IPT a novel, fully integrated control approach has been developed to overcome the drawbacks of state-of-the-art machine controls for ultra precision processes. Current control systems are often realized as decentralized solutions consisting of various computational hardware components for setpoint generation, machine control, HMI （human machine interface）, Slow Tool control and Fast Tool control. While implementing such a distributed control strategy, many disadvantages arise in terms of complex communication interfaces, discontinuous safety structures, synchronization of cycle times and the machining accuracy as a whole. The novel control approach has been developed as a fully integrated machine control including standard CNC （computer numerical control） and PLC （programmable logic controller） functionality, advanced setpoint generation methods, an extended HMI as well as an FPGA （field programmable gate array）-based controller for a voice coil driven Slow Tool and a piezo driven Fast Tool axis. As the new control system has been implemented as a fully integrated platform using digital communication via EtherCAT, a continuous safety strategy could be realized, the error sensitivity and EMC susceptibility could be significantly decreased and the overall process accuracy from setpoint generation over path interpolation to axes movements could be enhanced. The novel control at the same time offers additional possibilities of automation, process integration, online data acquisition and evaluation as well as error compensation methods.

NIPAD： a non-invasive power-based anomaly detection scheme for programmable logic controllers

Industrial control systems （ICSs） are widely used in critical infrastructures, making them popular targets for attacks to cause catastrophic physical damage. As one of the most critical components in ICSs, the programmable logic controller （PLC） controls the actuators directly. A PLC executing a malicious program can cause significant property loss or even casualties. The number of attacks targeted at PLCs has increased noticeably over the last few years, exposing the vulnerability of the PLC and the importance of PLC protection. Unfortunately, PLCs cannot be protected by traditional intrusion detection systems or antivirus software. Thus, an effective method for PLC protection is yet to be designed. Motivated by these concerns, we propose a non-invasive power- based anomaly detection scheme for PLCs. The basic idea is to detect malicious software execution in a PLC through analyzing its power consumption, which is measured by inserting a shunt resistor in series with the CPU in a PLC while it is executing instructions. To analyze the power measurements, we extract a discriminative feature set from the power trace, and then train a long short-term memory （LSTM） neural network with the features of normal samples to predict the next time step of a normal sample. Finally, an abnormal sample is identified through comparing the predicted sample and the actual sample. The advantages of our method are that it requires no software modification on the original system and is able to detect unknown attacks effectively. The method is evaluated on a lab testbed, and for a trojan attack whose difference from the normal program is around 0.63%, the detection accuracy reaches 99.83%.