scholarly journals Investigation of an Underwater Vectored Thruster Based on 3RPS Parallel Manipulator

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Tao Liu ◽  
Yuli Hu ◽  
Hui Xu ◽  
Mohamed El Ghami
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Parallel Manipulator ◽  
Driving Forces ◽  
Autonomous Underwater Vehicles ◽  
Affecting Factors ◽  
Compact Structure ◽  
Thrust Vectoring ◽  
Pid Algorithm ◽  
Control Scheme

Autonomous underwater vehicles (AUVs) are important and useful tool platforms in exploring and utilizing ocean resource. However, the effect of control surfaces would decrease even invalid complete in this condition, and it is very hard for conventional AUVs to perform detailed missions at a low forward speed. Therefore, solving this problem of AUVs becomes particularly important to increase the application scope of AUVs. In this paper, we present a design scheme for the vectored thruster AUV based on 3RPS parallel manipulator, which is a kind of parallel manipulator and has advantages of compact structure and reliable performance. To study the performance and characteristics of the proposed thrust-vectoring mechanism, a series of works about corresponding kinematic and dynamic analysis have been performed through the theoretical analysis and numerical simulation. In the part of kinematics, the inverse, forward kinematics, and workspace analysis of the thrust-vectoring mechanism is presented, and the numerical simulations are accomplished to prove the feasibility and effectiveness of this design in AUVs. In order to further verify feasibility of the thrust-vectoring mechanism, based on the considerations of various affecting factors, a dynamic model of the designed thrust-vectoring mechanism is established according to theoretical analysis, and the driving forces of the linear actuator are presented through a series of numerical simulations. In addition, a control scheme based on PID algorithm is proposed for the designed vectored thruster with considering various affecting factors and the application environment. Meanwhile, the control scheme is also established and verified in MATLAB Simscape Mutibody. A series of numerical simulations of the thrust-vectoring mechanism prove the feasibility of the vectored thruster. According to equipping the designed vectored thruster, the AUVs can overcome the limit of weakening the control ability at zero or low forward speeds, and this improvement also expands the application of it, which has been scaled greatly.

scholarly journals Anti-Synchronization of Fractional-Order Chaotic Circuit with Memristor via Periodic Intermittent Control

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Fanqi Meng ◽  
Xiaoqin Zeng ◽  
Zuolei Wang ◽  
Xinjun Wang
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Fractional Order ◽  
Lyapunov Stability ◽  
Stability Theory ◽  
Lyapunov Stability Theory ◽  
Intermittent Control ◽  
Chaotic Circuit ◽  
Control Scheme

In this paper, the anti-synchronization of fractional-order chaotic circuit with memristor (FCCM) is investigated via a periodic intermittent control scheme. Based on the principle of periodic intermittent control and the Lyapunov stability theory, a novel criterion is adopted to realize the anti-synchronization of FCCM. Finally, some examples of numerical simulations are exploited to verify the feasibility of theoretical analysis.

scholarly journals Theoretical Analysis and Design of an Innovative Coil Structure for Transcranial Magnetic Stimulation

2021 ◽  
Vol 11 (4) ◽  
pp. 1960
Author(s):  
Naming Zhang ◽  
Ziang Wang ◽  
Jinhua Shi ◽  
Shuya Ning ◽  
Yukuo Zhang ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Transcranial Magnetic Stimulation ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Magnetic Stimulation ◽  
Influential Factors ◽  
Intersection Angle ◽  
Electromagnetic Field Distribution ◽  
Analysis And Design ◽  
Coil Structure

Previous research showed that pulsed functional magnetic stimulation can activate brain tissue with optimum intensity and frequency. Conventional stimulation coils are always set as a figure-8 type or Helmholtz. However, the magnetic fields generated by these coils are uniform around the target, and their magnetic stimulation performance still needs improvement. In this paper, a novel type of stimulation coil is proposed to shrink the irritative zone and strengthen the stimulation intensity. Furthermore, the electromagnetic field distribution is calculated and measured. Based on numerical simulations, the proposed coil is compared to traditional coil types. Moreover, the influential factors, such as the diameter and the intersection angle, are also analyzed. It was demonstrated that the proposed coil has a better performance in comparison with the figure-8 coil. Thus, this work suggests a new way to design stimulation coils for transcranial magnetic stimulation.

Mathematical Model Establishment and Analysis on the Pipe Deformation under External Pressure with the Ovality

2013 ◽  
Vol 760-762 ◽  
pp. 2263-2266
Author(s):  
Kang Yong ◽  
Wei Chen
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Yield Strength ◽  
Residual Stresses ◽  
Numerical Simulations ◽  
Significant Influence ◽  
External Pressure ◽  
Pipe Diameter ◽  
Axial Loads ◽  
The Stability

Beside the residual stresses and axial loads, other factors of pipe like ovality, moment could also bring a significant influence on pipe deformation under external pressure. The Standard of API-5C3 has discussed the influences of deformation caused by yield strength of pipe, pipe diameter and pipe thickness, but the factor of ovality degree is not included. Experiments and numerical simulations show that with the increasing of pipe ovality degree, the anti-deformation capability under external pressure will become lower, and ovality affecting the stability of pipe shape under external pressure is significant. So it could be a path to find out the mechanics relationship between ovality and pipe deformation under external pressure by the methods of numerical simulations and theoretical analysis.

Impedance Control of Dual-Arm Systems Based on the Object with Senseless Force

2013 ◽  
Vol 765-767 ◽  
pp. 1920-1923
Author(s):  
Li Jiang ◽  
Yang Zhou ◽  
Bin Wang ◽  
Chao Yu
Keyword(s):  
Numerical Simulations ◽  
Relative Position ◽  
Position Control ◽  
Impedance Control ◽  
Force Sensors ◽  
Operational Space ◽  
Novel Approach ◽  
Control Scheme ◽  
Statics And Dynamics ◽  
Dual Arm

A novel approach to impedance control based on the object is proposed to control dual-arm systems with senseless force. Considering the motion of the object, the statics and dynamics of the dual-arm systems are modeled. Extending the dynamics of dual-arm system and the impedance of object to the operational space, impedance control with senseless force is presented. Simulations on a dual-arm system are carried out to demonstrate the performance of the proposed control scheme. Comparing with position control, results of numerical simulations show that the proposed scheme realizes suitable compliant behaviors in terms of the object, and minimizes the error of the relative position between the manipulators even without force sensors.

scholarly journals Design and Simulation of the Operating Speed Regulation Algorithm of Plot Cabbage Seed Combine Harvester

2020 ◽  
Vol 11 ◽  
pp. 160-169
Author(s):  
Mao Hanping ◽  
Wang Jiahui ◽  
Xing Gaoyong ◽  
Zuo Zhiyu ◽  
Li Qinglin
Keyword(s):  
Association Rules ◽  
Sql Server ◽  
Forward Speed ◽  
Large Delay ◽  
Pid Algorithm ◽  
Speed Regulation ◽  
Control Scheme ◽  
Cabbage Seed ◽  
Combine Harvester ◽  
Feed Volume

Aiming at the problems of the single control scheme, the few aspects of monitoring and diagnosis, and the large delay time of the plot combine harvester, this paper designs the forward speed control algorithm of the plot Chinese cabbage seed harvester. This paper studies the theory of association rules, has used SQL Server to build a database including the job parameters of the main monitoring objects, and has mined the association rules between the job parameters and the feed amount through Analysis Service. Combining the knowledge of association rules and ordinary fuzzy PID algorithm, the article has built a model and performed simulation verification. The results show that the algorithm can adjust the forward speed reasonably and quickly when the feed volume increases.

An Alternative Carcass Design to Prevent Flow-Induced Pulsations in Flexibles

2021 ◽  
Author(s):  
N. González Díez ◽  
S. P. C. Belfroid ◽  
T. Iversen Solfeldt ◽  
C. Kristiansen
Keyword(s):  
Pressure Drop ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Steel Strip ◽  
Point Of View ◽  
Theoretical Point ◽  
Adjacent Structures ◽  
Operational Constraints ◽  
Short Time ◽  
Fatigue Failures

Abstract Flow-induced pulsations (FLIP) are pressure oscillations generated inside of flexibles used in dry gas applications that can cause unacceptable vibration levels and eventually failure of equipment. Because of the design of inner layer of the flexibles, the carcass, the frequency of the pulsations is high, potentially leading to fatigue failures of adjacent structures in a relatively short time. The traditional carcass is made of a steel strip formed into an interlocked s-shape in a series of preforming and winding steps. To enable bending of the pipe, gaps are present between each winding with a shape that can cause FLIP. The gaps can be reduced, and the profiles optimized, but they will always be able to generate FLIP at a certain gas velocity. To remove the risk of FLIP in dry gas projects and ensure that operator does not get operational constraints, an alternative carcass design has been developed. This is essentially a conventional agraff carcass but with an additional cover strip to close the gap, making the resulting carcass nearly smooth bore in nature. With a smooth bore this carcass can be used for flexibles which have a risk of FLIP or to produce pipes with a lower internal roughness. This alternative design can be manufactured and can therefore build on the large manufacturing and design experience of the traditional strip carcass. This alternative carcass technology is to undergo a full qualification process, in which the risk of flow induced pulsations is an essential component. With the investigated alternative carcass design, the cavities present in the traditional agraff designs are covered. It is expected that the risk due to the appearance of FLIP is therefore eliminated. Theoretical analysis, numerical simulations and scaled experiments are used to explore the risk for the alternative technology to create FLIP. The theoretical analysis is based on existing knowledge and literature. The numerical simulations and scaled tests are done to generate direct evidence for the end statements resulting from the qualification process. Numerical simulations follow the power balance method presented by the same authors in earlier papers. The same applies to the techniques used for the scaled tests. The main outcome of the qualification presented here are the pressure drop performance and the anti-FLIP capabilities of the design. The new design performs significantly better than the nominal design carcass for the same purpose. The pressure drop coefficients found are close to those expected for a normal, non-corrugated pipe, and thus the recommendation given by the API 17J standard does not apply to this design. The pressure drop coefficient is dependent on the installation direction of the flexible with respect to the flow. No signs of FLIP are found for the nominal design of the investigated carcass technology. This is the case for either installation direction. This is explained from a theoretical point of view, but also numerical and experimental evidence are provided.

Kinematics and Dynamics Modeling of a New 4-DOF Cable-Driven Parallel Manipulator

2013 ◽  
pp. 249-265
Author(s):  
Hamoon Hadian ◽  
Yasser Amooshahi ◽  
Abbas Fattah
Keyword(s):  
Dynamic Model ◽  
Parallel Manipulator ◽  
Joint Space ◽  
Kinematics And Dynamics ◽  
Dynamics Modeling ◽  
Kinematic Constraint ◽  
Control Scheme ◽  
Minimum Number ◽  
Dynamical Properties ◽  
Computed Torque

This paper addresses the kinematics and dynamics modeling of a 4-DOF cable-driven parallel manipulator with new architecture and a typical Computed Torque Method (CTM) controller is developed for dynamic model in SimMechanics. The novelty of kinematic architecture and the closed loop formulation is presented. The workspace model of mechanism’s dynamic is obtained in an efficient and compact form by means of natural orthogonal complement (NOC) method which leads to the elimination of the nonworking kinematic-constraint wrenches and also to the derivation of the minimum number of equations. To verify the dynamic model and analyze the dynamical properties of novel 4-DOF cable-driven parallel manipulator, a typical CTM control scheme in joint-space is designed for dynamic model in SimMechanics.

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