Specifying and Synthesizing Energy-Efficient Production System Controllers that Exploit Braking Energy Recuperation

Reducing the energy consumption is a major concern in industrial production systems. One approach is recuperating the braking energy of robot axes. Ideally, their acceleration and deceleration phases should be synchronized so that the braking energy of one axis can be reused directly to accelerate another. This requires a detailed alignment of the axes' trajectories, but also a careful design of the overall discrete control. Finding an optimal control strategy manually, however, is difficult, as also many functional and safety requirements must be considered. We therefore propose an automated methodology that consists of three parts: (1) A scenario-based language to flexibly specify the discrete production system behavior, (2) an automated procedure to synthesize optimal control strategies from such specifications, including PLC code generation, and (3) a procedure for the detailed trajectory optimization. We describe the methodology, focusing on parts (1) and (2) in this paper, and present tool support and evaluation results

Generating Correct, Compact, and Efficient PLC Code from Scenario-based Assume-Guarantee Specifications

Cyber-physical systems can be found in many areas, e.g., manufacturing, health care or smart cities. They consist of many distributed components cooperating to provide increasingly complex functionality. The design and development of such a system is difficult and error-prone. To help engineers overcome these challenges we created a formal, scenario-based specification language. Short scenarios, i.e., event sequences, specify requirements and the desired behaviors by describing how components may, must, or must not behave. Scenarios provide an intuitive way for creating formal assume-guarantee (GR(1)) specifications, giving engineers easy access to simulation, for validating the specified behavior, and controller synthesis, for creating controller software which is correct by construction. In this paper we present an approach for generating Programmable Logic Controller (PLC) code from a scenario-based specification. Previous code generation efforts, including our own, created large, verbose source files causing some tools, e.g., compilers or editors, to perform slowly or even become unresponsive. Our new approach creates compact files, shifting significant amounts of code from executable instructions to data, to reduce the burden on the compiler and other tools. The generated code is efficient and introduces minimal to no latency between the occurrence of an event and the system's reaction to it

In vitro assessment of the nutritive value of mixtures of leaves from tropical fodder trees

SIGLEAvailable from British Library Document Supply Centre-DSC:D192324 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Distributed Execution of Scenario-based Specifications of Structurally Dynamic Cyber-Physical Systems

Cyber-physical systems are found in many areas, e.g., manufacturing or smart cities. They consist of multiple components that cooperate to provide the desired functionality. This need for cooperation causes complex interactions between components, which makes developing cyber-physical systems difficult, especially systems whose component structure changes dynamically at runtime. We have created a formal, scenario-based specification method which makes it easier to develop distributed cyber-physical systems. We previously presented an approach for the distributed execution of such specifications based on naive and inefficient broadcasting. In this paper we propose a more efficient approach which uses the available network resources more economically

Isomeric olefin tetracarbonyl complexes of tungsten(I): an infrared spectroelectrochemical study at low temperatures

In situ electrolysis within an optically transparent thin-layer electrochemical (OTTLE) cell was applied at 293-243 K in combination with FTIR spectroscopy to monitor spectral changes in the carbonyl stretching region accompanying oxidation of four tetracarbonyl olefin complexes of tungsten(0), viz., trans-[W(CO)(4)(eta(2)-ethene)(2)], trans-[W(CO)(4)(eta(2)-norbornene)(2)], [W(CO)(4)(eta(4)-cycloocta-1,5-diene)], and [W(CO)(4)(eta(4)-norbornadiene)]. In all cases, the one-electron-oxidized radical cations (17-electron complexes) have been identified by their characteristic nu(CO) patterns. For the bidentate diene ligands, the cis stereochemistry is essentially fixed in both the 18- and 17-electron complexes. The radical cation of the trans-bis(ethene) complex was observed only at 243 K, while at room temperature it isomerized rapidly to the corresponding cis-isomer. The thermal stability of the three studied radical cations in the cis configuration correlates with the relative strength of the W-CO bonds in the positions trans to the olefin ligand, which are more affected by the oxidation than the axial W-CO bonds. For the bulky norbornene ligands, their trans configuration in the bis(norbornene) complex remains preserved after the oxidation in the whole temperature range studied. The limited thermal stability of the radical cations of the trans-bis(alkene) complexes is ascribed to dissociation of the alkene ligands. The spectroelectrochemical results are in very good agreement with data obtained earlier by DFT (B3LYP) calculations