Liquid pipeline systems are widely used in liquid transportation systems such as water-supply and drainage systems, water cooling systems, and oil pipeline systems. Liquid flow rate measurement in a pipeline system is very important for effective repair and maintenance, high-efficiency operation and pipeline safety. In this paper, a liquid flow rate measurement method suitable for a liquid pipeline is proposed, in which an acoustic emission (AE) sensor is applied to the surface of the pipeline. We constructed a flow rate measurement system consisting of an AE sensor and a signal processing circuit for transforming AE signals generated by the liquid pipeline flow into a corresponding flow rate. The characteristics of the flow rate measurement system were experimentally determined, using tap water as the liquid. The results demonstrate the possibility that a steady flow rate can be measured with a repeatability of approximately 7% over regions in which the flow rate ranges from 4.0l/min to 11.0l/min in a pipeline with a diameter of 13.3mm or 0.5l/min to 4.0l/min in a pipeline with a diameter of 6.2mm. The scope of application of the proposed measurement system is discussed.

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A new bilateral master-slave control system for large-scale manipulators is proposed. The aim of the system is to cope with the large or heavy payloads and to accomplish assembling and deburring tasks accurately. To achieve this, three new control methods are introduced :, the new bilateral servomechanism combined with symmetric and force reflection types, a variable compliance control and disturbance force compensation. The effectiveness of these methods is confirmed through tests using a simple single joint model. In this paper, outlines of proposed control methods are presented and the results of the tests are discussed.

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The paper considers a stack of modular Load Sensing closed centre proportional directional control valves of a commercial excavator. All modules in the stack were disassembled and 3D models were prepared with the perspective of developing an accurate AMESim model. Previously, specific field measurements were also performed on the vehicle to set proper ground for subsequent validation of the simulation model. However, in the course of these in-depth investigations on all modules, some distinctive and rather peculiar aspects emerged. More precisely the pressure compensator featuring two independent spools, though located upstream of the main spool, is “normally” closed and in evident contrast with traditional pre-compensated solutions. In addition, the “global” Load Sensing signal driving the variable displacement pump differential pressure limiter is not originated by the highest load via proper selection in cascaded shuttle valves. The signal is rather generated by one of the two compensator spools through axial notches fed by a modest control flow directly derived from the pump delivery line. It is on this ground that, arbitrarily, due to their mixed origin, the term “hybrid” has been used in relation with these proportional directional control valves. The paper will detail all these findings and will further elucidate the AMESim model of one such modules. Finally simulated and experimental results will be contrasted to provide adequate support to the proposed modelling approach and a thorough analysis on specific parameters will be discussed.

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