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In this paper, to effectively solve the joint motion planning of a nine-DOF redundant hybrid boarding system in the process of ocean wave active compensation, we present a multi-task motion planning (MTMP) method for the redundant hybrid boarding system. First, the hybrid mechanism is disassembled into a six-DOF parallel mechanism and a three-DOF serial mechanism for kinematic analysis separately to obtain the Jacobian matrix of the hybrid mechanism in the task space. Then, according to the configuration characteristics of the hybrid mechanism and to avoid the defects of the pseudo-inverse and weighted pseudo-inverse methods in motion planning, several secondary tasks are proposed to constrain the motion planning of the hybrid mechanism. Based on simulations and comparisons, the results show that the MTMP method solves the problems of joint limitation, reverse compensation, overlap compensation, and divergence with time in the motion planning of the pseudo-inverse method and the weighted pseudo-inverse method. Meanwhile, the MTMP method has more superiority in the joint margin and compensation space range. [ABSTRACT FROM AUTHOR]

Due to their multiple advantages, piezoceramic materials have been widely used in structural health monitoring (SHM). Piezoceramic patch-based smart aggregate (SA) and spherical piezoceramic-based smart aggregate (SSA) have been developed for damage detection of concrete structures. However, the stress waves generated by these two types of transducers are limited by their geometry and are unsuitable for use in two-dimensional concrete structures (e.g., shear walls, floors and cement concrete pavements). In this paper, a novel embeddable tubular smart aggregate (TSA) based on a piezoceramic tube was designed, fabricated and tested for use in two-dimensional (2D) structures. Due to its special geometry, radially uniform stress waves can be generated, and thus the TSA is suitable for damage detection in planar structures. The suitability of the transducer for use in structural health monitoring was investigated by characterizing the ability of the transducer to transmit and measure stress waves. Three experiments, including impedance analysis, time of arrival analysis and sweep frequency analysis, were conducted to test the proposed TSA. The experimental results show that the proposed TSA is suitable for monitoring the health condition of two-dimensional concrete structures. [ABSTRACT FROM AUTHOR]