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Fluidic artificial muscles are popular in robotics and function as biomimetic actuators. Their pneumatic version has been widely investigated. A novel water hydraulic artificial muscle (WHAM) with high strength is developed in this study. WHAMs can be applied to underwater manipulators widely used in ocean development because of their environment-friendly characteristics, high force-to-weight ratio, and good bio-imitability. Therefore, the strength of WHAMs has been improved to fit the requirements of underwater environments and the work pressure of water hydraulic components. However, understanding the mechanical behaviors of WHAMs is necessary because WHAMs use work media and pressure control that are different from those used by pneumatic artificial muscles. This paper presents the static and dynamic characteristics of the WHAM system, including the water hydraulic pressure control circuit. A test system is designed and built to analyze the drive characteristics of the developed WHAM. The theoretical relationships among the amount of contraction, pressure, and output drawing force of the WHAM are tested and verified. A linearized transfer function is proposed, and the dynamic characteristics of the WHAM are investigated through simulation and inertia load experiments. Simulation results agree with the experimental results and show that the proposed model can be applied to the control of WHAM actuators.

This paper presents a developed dislocation superimposed method (DSM) for automatically extracting the component of impulsive signals from abnormal noise signals of an engine at a single speed range on the basis of the initial DSM. This method consists of three steps: using a correlation analysis to select an appropriate starting superposition point, superimposing abnormal sound signals to improve the signal-to-noise ratio, and intercepting superimposed signals to separate the fault component. Experimental results show that the developed DSM can effectively extract the fault characteristics of cylinder knocking and connecting rod bearing knocking. The developed approach can be applied to separate the fault characteristics of other types of rotating machines.

In this paper, coating removal characteristics of water jet by micro jet flow affected by cleaning parameters is analyzed. Numerical simulation of fluid field calculates the velocity and pressure distribution of a water jet impinging on a rigid wall, which is used for design experiments of coating removal affected by jet pressure, traversal speed, and repeated impacting times. The removal width is used as a measure of water jet coating removal capability. Experiment results show that the coating removal width is constant, independent with traversal speed or repeated times when total exposure time of waterjet impingement is fixed. According to results of coating removal by a linear moving water jet, this study also analyzes characteristics of coating removal by rotating jet disc, especially residual coating affected by rotational and moving speed of the cleaning disc. The research is helpful to improve the coating removal efficiency of cleaning disc devices.

Because of the high force-weight ratio of water hydraulic artificial muscle and its high compatibility with an underwater environment, the water hydraulic artificial muscle has received increasing attention due to its potential uses in marine engineering applications. The master-slave anthropopathic joint actuated by water hydraulic artificial muscles is light and small, and it has good maneuverability for underwater manipulators. However, the control methodologies for water hydraulic artificial muscle joint have not been thoroughly explored to date. This article introduces a master-slave control system of isomorphic artificial muscle joints. The water hydraulic artificial muscle joint acts as a slave joint working under the sea, and the pneumatic artificial muscle joint acts as a master joint that is operated by people. The rotation angle signal of the pneumatic artificial muscle joint is fed back as the input to regulate the rotation angle of the water hydraulic artificial muscle joint through a proportional-integral-derivative control. Meanwhile, the torque of the pneumatic artificial muscle joint is controlled by a proportional-integral-derivative controller based on the feedback of a two-force-transducer system in the water hydraulic artificial muscle joint as input. Therefore, the operator can control the movement and feel the load of the water hydraulic artificial muscle slave joint. Master-slave control experiments were performed, and the position/torque control results were analyzed using various loads and torque gains. This study contributes to the design and control of an anthropopathic underwater manipulator.