Rectangular Path Research Articles

Extension of continuous scanning laser Doppler vibrometry measurement for complex structures with curved surfaces

The continuous Scanning Laser Doppler Vibrometry (SLDV) developed on the base of the galvanometer scanner system has made it possible to quickly obtain the full field vibration responses within a rectangular area of the structure. In this paper, an arbitrary continuous scanning path generating method for Continuous Scanning Laser Doppler Vibometry (CSLDV) is further put forward in order to allow the CSLDV suitable for testing structures featured by complex shapes not just for regular areas. In the first step, the relationship between position of laser spot and the driving voltages of galvanometer scanner system has been described by a mathematical modeling. Then, a novel arbitrary scanning path generating strategy based on CSLDV is presented by deforming a normalization rectangular scanning path to an arbitrary continuous scanning path. The mapping relation between the normalization rectangular scanning path and arbitrary continuous scanning path is established using the reference points. In the second step, a compressor blade with curved surface was taken as an example for modal test using the proposed method. At the same time, a validated experiment was performed in SLDV. The results show the mode shapes derived from the extended CSLDV are in agreement with those from SLDV and the Modal Assurance Criterion (MAC) between the two are all greater than 0.96. They also demonstrate the feasibility and effectiveness of the proposed method for CSLDV test and show strong potential on further practical engineering applications.

Tracking control of redundant mobile manipulator: An RNN based metaheuristic approach

In this paper, we propose a topology of Recurrent Neural Network (RNN) based on a metaheuristic optimization algorithm for the tracking control of mobile-manipulator while enforcing nonholonomic constraints. Traditional approaches for tracking control of mobile robots usually require the computation of Jacobian-inverse or linearization of its mathematical model. The proposed algorithm uses a nature-inspired optimization approach to directly solve the nonlinear optimization problem without any further transformation. First, we formulate the tracking control as a constrained optimization problem. The optimization problem is formulated on position-level to avoid the computationally expensive Jacobian-inversion. The nonholonomic limitation is ensured by adding equality constraints to the formulated optimization problem. We then present the Beetle Antennae Olfactory Recurrent Neural Network (BAORNN) algorithm to solve the optimization problem efficiently using very few mathematical operations. We present a theoretical analysis of the proposed algorithm and show that its computational cost is linear with respect to the degree of freedoms (DOFs), i.e., O(m). Additionally, we also prove its stability and convergence. Extensive simulation results are prepared using a simulated model of IIWA14, a 7-DOF industrial-manipulator, mounted on a differentially driven cart. Comparison results with particle swarm optimization (PSO) algorithm are also presented to prove the accuracy and numerical efficiency of the proposed controller. The results demonstrate that the proposed algorithm is several times (around 75 in the worst case) faster in execution as compared to PSO, and suitable for real-time implementation. The tracking results for three different trajectories; circular, rectangular, and rhodonea paths are presented.

Personalized travel route recommendation algorithm based on improved genetic algorithm

The analysis of user trajectory information and social relationships in social media, combined with the personalization of travel needs, allows users to better plan their travel routes. However, existing methods take only local factors into account, which results in a lack of pertinence and accuracy for the recommended route. In this study, we propose a method by which user clustering, improved genetic, and rectangular region path planning algorithms are combined to design personalized travel routes for users. First, the social relationships of users are analyzed, and close friends are clustered into categories to obtain several friend clusters. Next, the historical trajectory data of users in the cluster are analyzed to obtain joint points in the trajectory map, these are matched according to the keywords entered by users. Finally, the search area is narrowed and the recommended travel route is obtained through improved genetic and rectangular region path planning algorithms. Theoretical analyses and experimental evaluations show that the proposed method is more accurate at path prediction and regional coverage than other methods. In particular, the average area coverage rate of the proposed method is better than that of the existing algorithm, with a maximum increasement ratio of 31.80%.

An Improved Fuzzy Logic Control Method for Path Tracking of an Autonomous Vehicle

Highlights This study focused on the path tracking accuracy of a two-wheel steering, two-wheel drive autonomous vehicle. An improved fuzzy logic control method (IFM) was designed to control the steering angle of the front wheels. The IFM was better than traditional pure pursuit and fuzzy logic control methods for automatic path tracking. Abstract. This article presents a path-tracking algorithm based on an improved fuzzy logic control method (IFM) that generates optimal steering angles for an autonomous wheeled vehicle to track a sequence of waypoints. The path-tracking algorithm was designed to focus on the vehicle performance, including tracking accuracy, stability, and convergence speed. A prototype vehicle with two-wheel steering and two-wheel drive (2WS-2WD) was developed as a test platform and equipped with a series of sensors for evaluating the IFM. In this study, we considered two variables, i.e., lateral deviation (d) and heading deviation (θ), as inputs for the control system. The output (δ) was the steering angle of the front wheels as controlled by an electric linear actuator. A maximum steering angle strategy was adopted for rapid convergence when the vehicle was far from the desired path or when the heading deviation was large. An update-line distance algorithm was used for finding the best turning time as the vehicle moved closer to the next waypoint. To validate the proposed algorithm, testing was performed to compare traditional pure pursuit (TPP), traditional fuzzy logic control method (TFM), and the IFM in tracking two types of paths (straight and rectangular). Traveling at 0.5 m s-1 and with a signal sampling period of 0.5 s, the prototype converged to the desired straight path from different initial states. When the vehicle reached a stable state, the steady-state error was between 5.0 and 6.5 cm with a mean of ≤6.0 cm. The settling distance in the straight path test was between 125.0 and 422.3 cm, and the convergence time was in the range of 11.5 to 16.0 s; the greater the initial deviation of the vehicle was, the greater the settling distance and settling time were. In the 15 m x 14 m rectangular path test, the overall mean error of the IFM was 14.4 cm when the initial lateral and heading deviations were 0, and the maximum deviation was 67.4 cm, which occurred at the corners. The test results show that the proposed IFM had better accuracy, stability, and convergence speed for path tracking when compared to the TPP and TFM algorithms.

A Waveguide Switch Based on Contactless Gap Waveguide Technology

A novel dual-pole dual-throw (DPDT) waveguide switch is proposed for high-power and low-loss applications. The proposed DPDT was designed based on the contactless properties of the gap waveguide technologies in the Ku frequency band. The DPDT was composed of two concentric contactless cylinders. Standard rectangular waveguide ports (WR 75) and waveguide paths are machined in the middle of these cylinders. The rotational movement of the inner cylinder is realized using two bearings in the top and bottom of the DPDT. The proposed structure is fabricated and the measured results are in good agreement with the simulated ones. The measured insertion loss and return loss for the aligned ports are better than 0.1 and 25 dB in the frequency band ranging from 11 to 13.5 GHz, respectively, and the measured isolation between two adjacent ports is better than 60 dB.

Effect of Aspect Ratio and Installation Direction on Channel Flow Heat Transfer Performance under a Wide Range of Reynolds Number

In recent years, in the cooling technology for high-power electronic devices such as power transistors used for drive motor control of electric vehicles and hybrid vehicles, a method of flowing a cooling fluid to a cooling substrate having a fin structure has become the main technology. The structure of the cooling fluid flow path is a channel flow through multiple narrow plate gaps to secure a heat transfer area. In this study, the heat transfer characteristics when the aspect ratio of the channel having a flat rectangular cross-section was changed were investigated in detail by experiments. Moreover, the difference in the heat transfer characteristic at the time of making a rectangular flow path into vertical installation and horizontal installation was also investigated.

Control Difuso Versus PID para un Sistema de Bola y Plataforma

En este artículo se presentan los resultados obtenidos en la performance de funcionamiento lograda mediante un controlador PID convencional y un controlador difuso, aplicados al control de una planta multivariable, no lineal e inherentemente inestable como lo es el dispositivo de bola y plataforma, utilizado como elemento para el estudio de diferentes técnicas de control. A partir del modelo matemático del sistema se diseñaron ambos controladores empleando la metodología clásica y la estructura de Mamdani respectivamente utilizando las herramientas computacionales de Matlab®. El procedimiento de verificación se realizó mediante la aplicación de consignas de entrada tendientes a imprimir a la bola una trayectoria circular y una rectangular. La comparación de las respuestas obtenidas por simulaciones muestra una clara ventaja en favor del controlador diseñado con técnicas difusas, aun considerando la presencia de ruido generado en los sensores y la aparición de eventuales perturbaciones externas.

PEDESTRIAN DEAD RECKONING USING SMARTPHONES SENSORS: AN EFFICIENT INDOOR POSITIONING SYSTEM IN COMPLEX BUILDINGS OF SMART CITIES

Abstract. This paper proposes an indoor positioning method using Pedestrian Dead Reckoning (PDR) based on the detection of the mode of the user’s smartphone. In the first step, to determine the mode of carrying the smartphone (Holding, Calling, Swinging) by suitably formed feature vectors based on sensor data, three classification algorithms (Decision Tree (DT), Support Vector Machine (SVM), and K-Nearest Neighbor (KNN)) are evaluated. From the classification algorithm perspective, the decision tree algorithm had the best performance in terms of processing time and classification. Secondly, to determine the user position, the step detection is performed by defining the upper threshold and time threshold for Acceleration norm values. The orientation component is obtained by combining accelerometer, magnetometer, and gyroscope data using Complementary Filtering and Principal Component Analysis based on Global Acceleration (PCA-GA) methods. The mean standard deviation along the direct path for the three modes of carrying (Holding, Calling, and Swinging) were obtained 6.22, 6.82, and 14.68 degrees, respectively. Localization experiments were performed on 3 modes of carrying a smartphone in a rectangular geometry path. The mean final error of positioning from ordinary walking for the three modes of holding (Calling, Holding, Swinging) were obtained 2.11, 2.34, and 4.5 m, respectively.

Dosimetric issues with simplified homogeneous body models in low frequency magnetic field exposure assessment

A simplified procedure, using circular disk models with homogeneous electric conductivity as representations for different body parts, has been proposed recently by product standard IEC 62822-3 for the assessment of magnetic field exposure in proximity to current-carrying conductors of welding equipment. Based on such simplified models, worst case coupling coefficients CCEi(I), i.e. maximum induced electric field strength, normalised for current and frequency, for body parts at different distances d to straight single and double wire arrangements, as well as rectangular loop-shaped current paths are tabulated in the standard. In this work we compared CCEi(I) values obtained by numerical computations with detailed anatomical models of the hand/forearm with the corresponding values given in IEC 62822-3 for current-carrying single wire conductors along the forearm at distances d = 30, 50 and 100 mm, respectively. Our results clearly indicated that the CCEi(I) given in the standard may substantially underestimate the actual exposure. Using average values for tissue conductivities the observed extent of underestimation was up to 8.9 dB (factor 2.79) and may be even higher for worst case combinations of tissue conductivities. The reasons for this substantial underestimation are the oversimplified geometry, i.e. the circular disk does not reflect anatomical constrictions of the induction area present in realistic hand/forearm geometries, as well as the missing conductivity contrast between different tissues in the homogeneous disk models. Results of exposure assessment and corresponding minimum distances to components of welding equipment obtained by the simplified disk model approach suggested by IEC 62822-3 should therefore be considered with caution.

A decoupling control for quadrotor UAV using dynamic surface control and sliding mode disturbance observer

This paper proposes a decoupling tracking controller for quadrotors using dynamic surface control (DSC) and second-order sliding mode disturbance observer (SMDO). The DSC used in this paper is improved with the sliding mode differentiators that replace the original low-pass filter, and the SMDO is utilized to restrain the influence of system uncertainties and external disturbances. In addition, instead of the roll attitude angle ( $$\varphi $$ ) and pitch attitude angle ( $$\theta $$ ), applying $$\sin {\varphi }$$ and $$\sin {\theta }$$ as control variables simplifies the analysis of stability. Moreover, a fuzzy logic-based method is utilized to compensate the influence of battery voltage changing during the procedure of thrust generation. The asymptotic tracking property of the closed-loop system is proven via the Lyapunov-based stability theory. Finally, the real-time experiment results, which contain a hovering case and rectangular path tracking case, are given to validate the practicability of the proposed method.

Effect of impeller outlet angle on hemo-compatibility of a centrifugal blood pump having rectangular cross-sectional flow paths

Effect of impeller outlet angle on hemo-compatibility of a centrifugal blood pump having rectangular cross-sectional flow paths

Cyclic Deformation and Low-Cycle Fatigue for 316LN Stainless Steel under Non-proportional Loading

The effects of loading path and strain amplitude ratio on the cyclic behavior and fatigue life were investigated on a 316LN nuclear grade stainless steel employing a series of symmetrically strain-controlled fatigue tests at room temperature. The loading paths of Uniaxial, Torsional, Proportional, Rhombic, Rectangular, and Circular were employed with the constant equivalent strain amplitude of 0.5%. The strain amplitude ratio of 2.35, 1.73 and 1.27, defined by the ratio of shear strain amplitude to the axial strain amplitude, was realized by changing the shear strain amplitude under Proportional, Rhombic, Rectangular and Elliptical loading paths. As expected, the significant non-proportional additional hardening was observed. It’s interesting to note that the axial cyclic stress response varied with the strain amplitude ratio, and the law was different under different loading paths. The fatigue life of all the tests were evaluated by three critical plane criteria proposed by Smith-Watson-Topper (SWT), Fatemi-Socie (FS) and Chen-Xu-Huang (CXH). Results show that the SWT criterion significantly overestimated the fatigue life of non-proportional loading because the effect of shear damage was not considered. The CXH criterion for tensile-type failure yielded good prediction results except for two torsional data points. The FS criterion provided better predictions than other models.

A 3D-printed 3-DOF tripedal microrobotic platform for unconstrained and omnidirectional sample positioning

This paper describes the design of a 3D-printed, three-degree-of-freedom (3-DOF) tripedal microrobotic platform that is capable of unlimited travel with sub-micrometer precision over a planar surface. The design combines piezoelectric stack actuators with compliant mechanical amplifiers to create stick-slip-style mechanisms for locomotion. A forward kinematic model of the stage’s motion is derived from its tripedal leg architecture. The model is then inverted for feedforward control of the platform. A prototype of the microrobot is constructed using low-cost 3D-printing technology. Experimental results demonstrate actuator stroke of 29.4 $$\upmu$$ m on average with a dominant resonance of approximately 860 Hz. Using open-loop feedforward control, the stage travels along a 3 mm $$\times$$ 3 mm, rectangular path. Feedback control through visual servoing is then simulated on a model that includes flexure dynamics, observed surface interactions, and camera sampling times, reducing the root-mean-square (RMS) tracking error by 90%. This controller is then implemented experimentally, resulting in 99% RMS position error reduction relative to feedforward-only control structure. The results show feasibility of creating functional 3D-printed, 3-DOF sample positioning stages.

Human Machine Interface Design for a 3 DoF Robot Manipulator

This paper represents a Human Machine Interface (HMI) design to control a 3 DoF robot manipulator. This manipulator has two parallelograms to make the moving platform always parallel to the ground. We used inverse kinematic analysis of the robot manipulator to control the end point location. Inverse kinematic results are verified using design parameters and end effector location. According to our algorithm, user defines the end point location from HMI, and then program solves inverse kinematics of the robot manipulator. The angles are sent to Arduino microcontroller to set the position of the servo motors. Using this HMI, the user picks and places the object in real time. The user can also give command to draw linear, circular and rectangular paths on the HMI.

EODL: Energy Optimized Distributed Localization Method in three-dimensional underwater acoustic sensors networks

The localization represents one of the most important aspects of underwater acoustic sensor networks, offering three-dimensional monitoring of marine environment, military detection and attack missions. This paper proposes the Energy Optimized Distributed Localization Method (EODL) as an efficient technique for the distributed sensor network localization based on the mobile beacon water. This technique employs an Autonomous Underwater Vehicle (AUV) as the mobile beacon. The moving path of the AUV in the three-dimensional water environment and the time interval of the broadcast transmitting are found by applying a qualitative analysis of the superiority of the rectangular path. In such a technique, the unknown sensor node position is calculated by monitoring beacon signals without requiring time synchronization between nodes. We consider the innermost intersection body for the localization process, to calculate the geometric intersection relation of different information signal ranges. Then, we calculate the location information of the nodes. Moreover, the localization error analysis of the method will be presented. We compare the simulation results of the proposed method (EODL) with the LDSN. In addition, the experimental results verify that the proposed method introduces less error and higher coverage rate comparing with the conventional methods.

Positioning Systems for Jiaolong Deep-Sea Manned Submersible: Sea Trial and Application

A crucial issue that cannot be ignored in deep-sea resource surveys and scientific research is underwater positioning and navigation of deep-sea manned submersibles. Ultra-short baseline (USBL) is an important technical method for performing underwater positioning and tracking of manned submersibles and ensuring the safety of their underwater operations. Using USBL, the mothership can obtain the manned submersible's position in real time. Furthermore, the manned submersible can obtain its own position at longer time intervals using digital underwater acoustic communication to assist the pilot in driving. Long baseline (LBL) is a significant supplement to USBL because it is an independent positioning system that provides more accurate and real-time navigation and positioning data for manned submersibles in large areas and deep seas. In this paper, we analyzed USBL sea-trial calibration, its application in real diving, and details of LBL sea-trial using the Jiaolong deep-sea manned submersible as a case study. Data measured during 10 consecutive dives of the Jiaolong manned submersible are utilized to analyze the USBL positioning performance. We found that the positioning performance (relative slant range error, relative depth error, and data efficiency) is consistent with calibration results. Finally, a rectangular path with a length of 900 m and breadth of 300 mis designed to verify LBL performance in deep sea. The LBL sea-trial results show that the positioning accuracy of LBL is better than that of USBL. The USBL positioning performance is affected by the distance from the mothership and its heading.

Parametric Optimization of Link Lengths of A SCARA Robot for Deburring Of Rectangular Paths

Selective Compliance Articulated Robot Arm (SCARA) manipulator is a well-defined manipulator in both research and commercial usage point of view. SCARA is extensively used for pick and place applications, especially for electronic components. The objective of the paper is to optimize the link lengths of a SCARA robot for deburring of rectangular components within the work volume. The present analysis is carried out using MATLAB (Matrix Laboratory) by positioning the rectangular component parallel to the base of a SCARA robot at different position possibilities.

Machining robot with vibrational motion and 3D printer-like data interface

In this paper, a vibration motion control is proposed and implemented on a foamed polystyrene machining robot to suppress the generation of undesirable cusp marks, and the basic performance of the controller is verified through machining experiments of foamed polystyrene. Then, a 3 dimensional (3D) printer-like data interface is proposed for the machining robot. The 3D data interface enables to control the machining robot directly using stereolithography (STL) data without conducting any computer-aided manufacturing (CAM) process. This is done by developing a robotic preprocessor that helps to remove the need for the conventional CAM process by directly converting the STL data into cutter location source data called cutter location (CL) or cutter location source (CLS) data. The STL is a file format proposed by 3D systems, and recently is supported by many computer aided design (CAD)/CAM softwares. The STL is widely used for rapid prototyping with a 3D printer which is a typical additive manufacturing system. The STL deals with a triangular representation of a curved surface geometry. The developed 3D printer-like data interface allows to directly control the machining robot through a zigzag path, rectangular spiral path and circular spiral path generated according to the information included in STL data. The effectiveness and usefulness of the developed system are demonstrated through actual machining experiments.

Near perfect path generation of corners chamfered rectangle and single synthesis cam-link mechanism to generate special-slot path

ABSTRACTOptimal synthesis of adjustable four-bar linkage to generate corners chamfered rectangle (CCR) and fully chamfered rectangle (FCR) path is proposed. Precise and continuous path generation is verified using reconstructed adjustable parameter curve (RAPC) method which uses harmonic spacing of precision points on the CCR and FCR path profiles. Single stage synthesis approach is proposed to convert two degrees of freedom (DOF) adjustable four-bar mechanism to one DOF using RAPC method. Simulation of motion of adjustable four-bar mechanism to generate special-slot path for uniform angular velocity is performed. Virtual prototype of special-slot path generating mechanism with one DOF is performed. Optimal dimensional synthesis of these mechanisms is done using hybrid optimization method combining genetic algorithm followed by pattern search of MATLAB optimization tools. Convergence of objective function during the hybrid optimization processes is verified. Results and conclusion prove that the RAPC method generates precise CCR and FCR paths, verifies adjustable parameter value for rectangular path generation and converts two DOF adjustable four-bar mechanism to one DOF six-bar mechanism.

Vision-based Tracking by a Quadrotor on ROS

Real-time following of a moving target by a flying tracker without radar detection and GPS reception inspires vision-based tracking through the use of surveillance camera, laser-scanned lidar, and SLAM (simultaneous localization and mapping). In this paper, we propose vision-based tracking of a moving target in three consecutive steps, image processing, coordinate transformation and trajectory following. A testing platform containing two spawned quadrotors as target and tracker is developed on ROS, from which sequence of images are generated by an on-board camera of the tracker while the target moves along a rectangular path on the ground. An image processing algorithm based on target recognition is proposed to achieve visual tracking on image frames. Coordinate transformation is established to recover the original target trajectory as the desired path of the tracker in the real world from the image processing algorithm. The target following control law then moves the tracker along the desired trajectory point-by-point through velocity control.