Novel Methodology for Inflection Circle based synthesis of Straight Line Crank Rocker Mechanism

Emerging fields like Compact Compliant Mechanisms have created newer/novel situations for application of straight line mechanisms. Many of these situations in Automation and Robotics are multidisciplinary in nature. Application Engineers from these domains are many times uninitiated in involved procedures of synthesis of mechanisms and related concepts of Path Curvature Theory. This paper proposes a predominantly graphical approach using properties of Inflection Circle to synthesize a crank rocker mechanism for tracing a coupler curve which includes the targeted straight line path. The generated approximate straight line path has acceptable deviation in length, orientation and extent of approximate nature well within the permissible ranges. Generation of multiple choices for the link geometry is unique to this method. To ease the selection, a trained Artificial Neural Network (ANN) is developed to indicate relative length of various options generated. Using studied unique properties of Inflection Circles a methodology for anticipating the orientation of the straight path vis-à-vis the targeted path is also included. Two straight line paths are targeted for two different crank rockers. Compared to the existing practice of selecting the mechanism with some compromise due to inherent granularity of the data in Atlases, proposed methodology helps in indicating the possibility of completing the dimensional synthesis. The case in which the solution is possible, the developed solution is well within the design specifications and is without a compromise.

Straight-line path-following control for roll-out phase of the equipped-skid aircraft

The paper deals with straight-line path-following control design for the aircraft equipped with skid landing gears. First, a simple yet accurate on-ground aircraft model is established, which takes into account the effects of the aerodynamic and ground forces. To improve the directional stability of the aircraft during the roll-out phase, a novel skid with variable friction coefficients is proposed. Second, the path-following problem is converted to the attitude control problem by constructing a guiding vector field that generates the commanded course, and then an improved error function is proposed to manage the trade-off between the convergence rate and the strong lateral maneuvers. To achieve a good performance in path following, the incremental nonlinear control allocation is applied to make full use of three available actuators (nose wheel, variable friction skid, and rudder). The expected path here is the runway centerline so as to avoid runway excursions. Finally, the effectiveness and robustness of the path-following control are validated on different initial conditions. Results show that the proposed skid structure and control scheme are propitious to enhancing the resistance to crosswind. Moreover, the maximum lateral displacement during the path-following process decreases, especially in the low-speed region.

Collision-Free Motion Planning for an Aligned Multiple-turret System Operating in Extreme Environment

Instead of using the tedious process of manual positioning, an off-line path planning algorithm has been developed for military turrets to improve their accuracy and efficiency. In the scope of this research, an algorithm is proposed to search a path in three different types of configuration spaces which are rectangular-, circular-, and torus-shaped by providing three converging options named as fast, medium, and optimum depending on the application. With the help of the proposed algorithm, 4-dimensional (D) path planning problem was realized as 2-D + 2-D by using six sequences and their options. The results obtained were simulated and no collision was observed between any bodies in these three options.

Development of a New Reusable and User-Centric General-Use Mask for Averting Respirator Supply Crisis in the Healthcare Sector

Healthcare workforce implements general-use masks for low and/or moderate barrier protection in sterile environments. However, these masks are often unavailable in pandemic situations due to a strain on supply/demand logistics. In such cases, establishing development of respiratory protection within the organization may be beneficial. Our work presents one such novel method of designing customized masks by considering facial anthropometrics of the specific sample population. In fact, such a design may provide a more efficient fit with the users as compared to currently available masks, which are often designed for a much wider range of people. The protocol followed a fast-paced method of obtaining facial data (~2.8 mins/participant), and a data-driven approach for extracting design profiles. We have demonstrated the same through a pilot study, which involved recruiting a group of 7 participants with ethnic and gender variation. A total of 7 landmarks representing zygomatic process of the temporal, angle of mandible, zygomatic arch, nasal-maxillary region, and apex of nose, mid-lips and the chin were selected. Analysis included determining closest, mid-points, and farthest points for each landmark among the entire datasets. Results indicated that the landmarks: Apex of Nose, Midlips and Chin represented a straight-line path with a lateral shift of ~4.58 inches between the closest and farthest dimensions from the nose point, based on which the facepiece was designed. Meanwhile, geometric transformations consisting of several construction lines and bisectors were used along with obtained data from zygomatic arch, process of temporal, and angle of mandible landmarks to determine the contours of the straps for securing the mask. Our design addresses common issues in masks like discomfort around the ear, humidity, and reuse, by provision of a novel mounting method, fabric-based materials, and sleeve for replacement of filters, respectively. The proposed concept of the mask and the methods followed could also be applied in broader applications including manufacturing/construction and also daily-life activities besides hospital environments.

Effect of the Agglomerate Geometry on the Effective Electrical Conductivity of a Porous Electrode

The study of the microstructure of random heterogeneous materials, related to an electrochemical device, is relevant because their effective macroscopic properties, e.g., electrical or proton conductivity, are a function of their effective transport coefficients (ETC). The magnitude of ETC depends on the distribution and properties of the material phase. In this work, an algorithm is developed to generate stochastic two-phase (binary) image configurations with multiple geometries and polydispersed particle sizes. The recognizable geometry in the images is represented by the white phase dispersed and characterized by statistical descriptors (two-point and line-path correlation functions). Percolation is obtained for the geometries by identifying an infinite cluster to guarantee the connection between the edges of the microstructures. Finally, the finite volume method is used to determine the ETC. Agglomerate phase results show that the geometry with the highest local current distribution is the triangular geometry. In the matrix phase, the most significant results are obtained by circular geometry, while the lowest is obtained by the 3-sided polygon. The proposed methodology allows to establish criteria based on percolation and surface fraction to assure effective electrical conduction according to their geometric distribution; results provide an insight for the microstructure development with high projection to be used to improve the electrode of a Membrane Electrode Assembly (MEA).

Vector field path following of a full-wing solar-powered Unmanned Aerial Vehicle (UAV) landing based on Dubins path: a lesson from multiple landing failures

The full-wing solar-powered UAV has a large aspect ratio, special configuration, and excellent aerodynamic performance. This UAV converts solar energy into electrical energy for level flight and storage to improve endurance performance. The UAV only uses a differential throttle for lateral control, and the insufficient control capability during crosswind landing results in a large lateral distance bias and leads to multiple landing failures. This paper analyzes 11 landing failures and finds that a large lateral distance bias at the beginning of the approach and the coupling of base and differential throttle control is the main reason for multiple landing failures. To improve the landing performance, a heading angle-based vector field (VF) method is applied to the straight-line and orbit paths following and two novel 3D Dubins landing paths are proposed to reduce the initial lateral control bias. The results show that the straight-line path simulation exhibits similar phenomenon with the practical failure; the single helical path has the highest lateral control accuracy; the left-arc to left-arc (L-L) path avoids the saturation of the differential throttle; and both paths effectively improve the probability of successful landing.

An on-line path planning of assembly robots based on FOVS

To improve the accuracy and efficiency of path planning for the mechanical assembly process of products, an on-line path planning method for mechanical assembly process robots based on visual field space is proposed in this paper. Firstly, to predict and describe the assembly process, the concept of field-of-view space (FOVS) is proposed. Secondly, image processing is carried out by knowledge base to judge the assembly type and current assembly state, and the initial assembly path is given. Then, the assembly process is integrated and solved, and the location estimation of obstacles are given according to the FOVS. Finally, the ant colony algorithm is improved to get the final assembly optimization path. Comparing the algorithm with the ACS algorithm in the aspect of path planning. The length of path planning is reduced by 2%, and the algorithm time is reduced by 0.5s, the accuracy and efficiency have been effectively improved. the result shows that the algorithm is effective.

A Rare Case Report of Unusual Path of Left Internal Jugular Central Line

Central venous cannulation is the most common procedure performed in perioperative setting and intensive care unit. Many case reports reported unusual positioning of central line catheters. Here, we would like to report a case of central line path in persistent left superior vena cava, a rare entity with a course similar to the right internal jugular central line. Preoperative computed tomography chest showed duplex superior vena cava which was not reported.