Identification of Near-Fault Impulsive Signals and Their Initiation and Termination Positions with Convolutional Neural Networks

Ground motions recorded in near-fault regions may contain pulse-like traces in the velocity domain. Their long periodicity can identify such signals with large amplitudes. Impulsive signals can be hazardous for buildings, creating large demands due to their long periods. In this study, a dataset was collected from various data centres. Initially, all the impulsive signals, which are in reality rare, are manually identified. Furthermore, then, synthetic velocity waveforms are created to increase the number of impulsive signals by using the model developed by Mavroeidis and Papageorgiou, and k−2 kinematic modelling. In accordance, a convolutional neural network (CNN) was trained to detect impulsive signals by using these synthetic impulsive signals and ordinary signals. Furthermore, manually labelled impulsive signals are used to detect the initiation and the termination positions of impulsive signals. To do so, the velocity waveform and position and amplitude information of the maximum and minimum points are used. Once the model detects the positions, the period of the pulse is calculated by analysing spectral periods. Although our detection algorithm works relatively worse than three robust algorithms used for benchmarks, it works significantly better in the determination of initiation and termination positions. At this moment, our models understand the features of the impulsive signals and detect their location without using any thresholds or any formulations that are heavily used in previous studies.

A 3D-Printable Robotic Gripper Based on Thick Panel Origami

Origami has been a source of inspiration for the design of robots because it can be easily produced using 2D materials and its motions can be well quantified. However, most applications to date have utilised origami patterns for thin sheet materials with a negligible thickness. If the thickness of the material cannot be neglected, commonly known as the thick panel origami, the creases need to be redesigned. One approach is to place creases either on top or bottom surfaces of a sheet of finite thickness. As a result, spherical linkages in the zero-thickness origami are replaced by spatial linkages in the thick panel one, leading to a reduction in the overall degrees of freedom (DOFs). For instance, a waterbomb pattern for a zero-thickness sheet shows multiple DOFs while its thick panel counterpart has only one DOF, which significantly reduces the complexity of motion control. In this article, we present a robotic gripper derived from a unit that is based on the thick panel six-crease waterbomb origami. Four such units complete the gripper. Kinematically, each unit is a plane-symmetric Bricard linkage, and the gripper can be modelled as an assembly of Bricard linkages, giving it single mobility. A gripper prototype was made using 3D printing technology, and its motion was controlled by a set of tendons tied to a single motor. Detailed kinematic modelling was done, and experiments were carried out to characterise the gripper’s behaviours. The positions of the tips on the gripper, the actuation force on tendons, and the grasping force generated on objects were analysed and measured. The experimental results matched well with the analytical ones, and the repeated tests demonstrate that the concept is viable. Furthermore, we observed that the gripper was also capable of grasping non-symmetrical objects, and such performance is discussed in detail in the paper.

Kinematic Modelling of a Panel Enclosed Mechanism

This thesis presents a new method for kinematic modeling and analysis of a six degree-of-freedom parallel robot enclosed by a number of sliding panels, called panel enclosed mechanism. This type of robots has been seen in applications where mechanisms are covered by changeable surfaces, such as aircraft morphing wings made of variable geometry truss manipulators. Based on the traditional parallel robot kinematics, the proposed method is developed to model the motions of a multiple segmented telescopic rigid panels that are attached to the moving branches of the mechanism. Through this modeling and analysis, a collision detection algorithm is proposed to analyze the collisions that could occur between adjacent sliding panels during motion over the workspace of the mechanism. This algorithm will help to design a set of permissible panels used to enclose the mechanism free of collision. A number of cases are simulated to show the effectiveness of the proposed method. In addition, an extra link is added to provide an additional degree-of-freedom. Various search methods are employed to evaluate optimal orientation angles to minimize collisions of adjacent panels. Finally, the effect of increased mobility is analyzed and validated as a potential solution to reduce panel collisions.

Kinematic Modelling of a Panel Enclosed Mechanism

This thesis presents a new method for kinematic modeling and analysis of a six degree-of-freedom parallel robot enclosed by a number of sliding panels, called panel enclosed mechanism. This type of robots has been seen in applications where mechanisms are covered by changeable surfaces, such as aircraft morphing wings made of variable geometry truss manipulators. Based on the traditional parallel robot kinematics, the proposed method is developed to model the motions of a multiple segmented telescopic rigid panels that are attached to the moving branches of the mechanism. Through this modeling and analysis, a collision detection algorithm is proposed to analyze the collisions that could occur between adjacent sliding panels during motion over the workspace of the mechanism. This algorithm will help to design a set of permissible panels used to enclose the mechanism free of collision. A number of cases are simulated to show the effectiveness of the proposed method. In addition, an extra link is added to provide an additional degree-of-freedom. Various search methods are employed to evaluate optimal orientation angles to minimize collisions of adjacent panels. Finally, the effect of increased mobility is analyzed and validated as a potential solution to reduce panel collisions.