A New Method for Precision of a Serpentine Snake-Like Robot

2012 ◽  
Vol 232 ◽  
pp. 377-382 ◽  
Author(s):  
Siavash Sarrafan ◽  
Alireza Akbarzadeh
Keyword(s):  
Structural Parameters ◽  
Positional Error ◽  
Control Parameters ◽  
Arc Length ◽  
Gait Control ◽  
Snake Robot ◽  
Geometrical Error ◽  
Input Parameters ◽  
Winding Angle ◽  
Different Levels

In this paper, a planar snake-like robot travelling in serpentine locomotion is considered. A method is presented where structural and gait control parameters are used to obtain the minimum snake-robot positional error, geometrical error. Two structural parameters, length and mass of each link as well as two control parameters, initial winding angle (α0) and arc length (s) are considered. Each of the four input parameters is examined at five different levels. The method uses Taguchi experimental techniques and analyzes effects of uncertainties by means of adding noise to the robot parameters. Significance of the input parameters is also determined using Analysis of Variance.

scholarly journals Reducing parametric uncertainty in limit-cycle oscillation computational models

2017 ◽  
Vol 121 (1241) ◽  
pp. 940-969 ◽  
Author(s):  
R. Hayes ◽  
R. Dwight ◽  
S. Marques
Keyword(s):  
Limit Cycle ◽  
Computational Models ◽  
Structural Parameters ◽  
Parametric Uncertainty ◽  
Limit Cycle Oscillation ◽  
Posterior Distributions ◽  
Input Parameters ◽  
Data Points ◽  
Cycle Oscillation ◽  
True Values

ABSTRACTThe assimilation of discrete data points with model predictions can be used to achieve a reduction in the uncertainty of the model input parameters, which generate accurate predictions. The problem investigated here involves the prediction of limit-cycle oscillations using a High-Dimensional Harmonic Balance (HDHB) method. The efficiency of the HDHB method is exploited to enable calibration of structural input parameters using a Bayesian inference technique. Markov-chain Monte Carlo is employed to sample the posterior distributions. Parameter estimation is carried out on a pitch/plunge aerofoil and two Goland wing configurations. In all cases, significant refinement was achieved in the distribution of possible structural parameters allowing better predictions of their true deterministic values. Additionally, a comparison of two approaches to extract the true values from the posterior distributions is presented.

Toleranced Designs of Cooled Turbine Blades Through Probabilistic Thermal Analysis of Manufacturing Variability

2007 ◽  
Author(s):  
Curtis W. Moeckel ◽  
David L. Darmofal ◽  
T. Robert Kingston ◽  
Robert J. G. Norton
Keyword(s):  
Turbine Blades ◽  
Probabilistic Approach ◽  
Cost Savings ◽  
Large Scatter ◽  
Cooling Flow ◽  
Blade Cooling ◽  
Input Parameters ◽  
Frame Work ◽  
Parametric Cad ◽  
Different Levels

Manufacturing variability is likely the primary cause of a large scatter in the life of gas turbine hot section components. This paper investigates manufacturing variability and its effect on first-stage turbine blades through the use of a parametric CAD model, automated CAD regeneration software, and a parametric finite element thermal model. The probabilistic approach used is substantiated due to differences that arise when input parameters vary at different levels, for example the engine-to-engine and blade-to-blade level. Schemes are proposed to improve robustness through tolerancing out input parameters in ranges of the distributions that make nonconformances more likely. A frame-work is presented for calculating the potential number of prevented non-conformances and the corresponding cost savings associated with various tolerancing schemes. Blade-to-blade cooling flow variability, especially as a result of film-hole diameter variability in critical locations, is identified as the most likely candidate for parameter tolerancing. More effective is a combined two-factor tolerancing scheme which additionally tolerances gas path temperature.

scholarly journals Prediction and Evaluation of Dynamic Variations of the Thermal Environment in an Air-Conditioned Room Using Collaborative Simulation Method

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5378
Author(s):  
Lin He ◽  
Shunan Zhao ◽  
Guowen Xu ◽  
Xin Wu ◽  
Junlong Xie ◽  
...  
Keyword(s):  
Air Temperature ◽  
Temperature Difference ◽  
Thermal Environment ◽  
Structural Parameters ◽  
Simulation Method ◽  
Outer Diameter ◽  
Control Parameters ◽  
Temperature Uniformity ◽  
Collaborative Simulation ◽  
Dynamic Variations

In this study, a collaborative simulation method is proposed to predict dynamic variations of the thermal environment in an air-conditioned room. The room thermal environment was predicted and analyzed by varying the structural and control parameters of the air conditioner considering the dynamic coupling effect. Connections and regularities were established between the applicable parameters and evaluation indices of the thermal environment. The simulation results demonstrated the interactions among the system structural parameters, control parameters, and the thermal environment. Within a certain parameter range, the evaporator structure exhibited a significant effect on temperature uniformity and vertical air temperature difference, followed by predicted mean vote (PMV) and draught rate (DR). The associated evaluation indices were sensitive to fin spacing, tube spacing, and tube outer diameter, in the same order, which were structural parameters of the evaporator. The effect of the air supply angle on the vertical air temperature difference was evident; however, its influence on the PMV, DR, and temperature uniformity did not indicate consistent variations.

Fabrication of bioinspired grid-crimp micropatterns by melt electrospinning writing for bone-ligament interface study

2022 ◽  
Author(s):  
Junjie Xiong ◽  
Han Wang ◽  
Xingzi Lan ◽  
Yaqi Wang ◽  
Zixu Wang ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Processing Parameters ◽  
Cell Alignment ◽  
Native Structure ◽  
3D Scaffold ◽  
Native Bone ◽  
Melt Electrospinning ◽  
Fiber Spacing ◽  
Interface Study ◽  
Different Levels

Abstract Many strategies have been adopted to engineer bone-ligament interface, which is of great value to both the tissue regeneration and the mechanism understanding underlying interface regeneration. However, how to recapitulate the complexity and heterogeneity of the native bone-ligament interface including the structural, cellular and mechanical gradients is still challenging. In this work, a bioinspired grid-crimp micropattern fabricated by melt electrospinning writing (MEW) was proposed to mimic the native structure of bone-ligament interface. The printing strategy of crimped fiber micropattern was developed and the processing parameters were optimized, which were used to mimic the crimp structure of the collagen fibrils in ligament. The guidance effect of the crimp angle and fiber spacing on the orientation of fibroblasts was studied, and both of them showed different levels of cell alignment effect.. MEW grid micropatterns with different fiber spacings were fabricated as bone region. Both the alkaling phosphatase activity and calcium mineralization results demonstrated the higher osteoinductive ability of the MEW grid structures, especially for that with smaller fiber spacing. The combined grid-crimp micropatterns were applied for the co-culture of fibroblasts and osteoblasts. The results showed that more cells were observed to migrate into the in-between interface region for the pattern with smaller fiber spacing, suggested the faster migration speed of cells. Finally, a cylindrical triphasic scaffold was successfully generated by rolling the grid-crimp micropatterns up, showing both structural and mechanical similarity to the native bone-ligament interface. In summary, the proposed strategy is reliable to fabricate grid-crimp triphasic micropatterns with controllable structural parameters to mimic the native bone-to-ligament structure, and the generated 3D scaffold shows great potential for the further bone-ligament interface tissue engineering.

scholarly journals PI/backstepping control of snake robot optimazed by genetic algorithm

2014 ◽  
Vol 3 (2) ◽  
pp. 99 ◽  
Author(s):  
Maryam Jafari ◽  
Aref Shahmansoorian
Keyword(s):  
Genetic Algorithm ◽  
Robust Control ◽  
Sliding Mode ◽  
Tracking Error ◽  
Backstepping Control ◽  
Control Parameters ◽  
Motion Pattern ◽  
Snake Robot ◽  
The Stability ◽  
And Control

This paper describes the design of robust control of PI/Backstepping for the snake robot to control the joints motion. First, the stability of the method is proved and, by applying this controller to the robot, its motion pattern is controlled in a way that it can move and follow by mimicking the motion of real snakes on the predefined trajectories. Then, the control parameters are optimized using the Genetic Algorithm (GA). Comparing obtained results with sliding mode revealed that, the former has significantly reduced the tracking error and control energy; in addition there is no chattering phenomenon. Keywords: Snake Robot, PI/Backstepping Control, Genetic Algorithm, Control Energy.

A Study on the Optimization of the Cutting Parameters in Turning of Pure Titanium

2020 ◽  
Vol 896 ◽  
pp. 299-304
Author(s):  
Dumitru Panduru ◽  
Emil Nicusor Patru ◽  
Nicolae Craciunoiu ◽  
Marin Bica
Keyword(s):  
Automotive Industry ◽  
Orthogonal Array ◽  
Pure Titanium ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Point Of View ◽  
Depth Of Cut ◽  
Specific Strength ◽  
Input Parameters ◽  
Different Levels

Pure titanium and its alloys are widely used in automotive industry, due to their high specific strength (strength/density) and excellent corrosion resistance, despite of their high cost. From point of view of machining, turning experiments of the pure titanium involve few input parameters (cutting speed, feed rate or depth of cut) and investigation of their influence on the response parameters of the cutting process (temperature in this case). Objectives of this study are to find the optimal combination of the input parameters, so that the temperature in turning of pure titanium to be minimum. In order to use a small number of experiments, two major tools, signal-to-noise (one of the three characteristic: nominal is the best, smaller the better or larger is better) and orthogonal array as statistical method can be used. For this study, a L9 (34) orthogonal array was considered adequate, so nine experiments was conducted using each factor (speed, feed and depth of cut) at three different levels.

Multiobjective optimization of friction stir weldments of AA2014-T651 by teaching–learning-based optimization

2019 ◽  
Vol 234 (6) ◽  
pp. 1146-1155 ◽  
Author(s):  
Borigorla Venu ◽  
L Suvarna Raju ◽  
K Venkata Rao
Keyword(s):  
Mechanical Properties ◽  
Optimization Algorithm ◽  
Objective Functions ◽  
Friction Stir ◽  
Optimization Of Process Parameters ◽  
Input Parameters ◽  
Teaching Learning Based Optimization ◽  
Teaching Learning ◽  
Tool Pin ◽  
Different Levels

This study focuses on optimization of process parameters, which may result in improved mechanical properties of the friction stir weldments of AA2014-T651. Plain taper and threaded taper cylindrical tool pin profiles were used for the study. A set of experiments was conducted at different levels of tool rotational and weld speeds using two tool pin profiles. Mechanical properties such as tensile strength, yield strength, impact strength, percentage of elongation, and hardness were measured. Objective functions are developed for the five mechanical properties in terms of input parameters. The input parameters were optimized using teaching–learning-based optimization algorithm technique to improve mechanical properties. The teaching–learning-based optimization algorithm suggested three best combinations such as combination-I (940 r/min and 32 mm/min), combination-II (1100 r/min and 40 mm/min), and combination-III (1205 r/min and 45 mm/min). The optimization is also validated with experimental results.

scholarly journals Modeling and Mechanism Investigation of Inertia and Damping Issues for Grid-Tied PV Generation Systems with Droop Control

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1985 ◽  
Author(s):  
Yongbin Wu ◽  
Donghui Zhang ◽  
Liansong Xiong ◽  
Sue Wang ◽  
Zhao Xu ◽  
...  
Keyword(s):  
Steady State ◽  
Structural Parameters ◽  
Frequency Stability ◽  
Operating Point ◽  
Damping Capacity ◽  
Droop Control ◽  
Control Parameters ◽  
Outer Loop ◽  
Dc Voltage ◽  
Dc Bus

Inertia effect and damping capacity, which are the basic characteristics of traditional power systems, are critical to grid frequency stability. However, the inertia and damping characteristics of grid-tied photovoltaic generation systems (GPVGS), which may affect the frequency stability of the grid with high proportional GPVGS, are not yet clear. Therefore, this paper takes the GPVGS based on droop control as the research object. Focusing on the DC voltage control (DVC) timescale dynamics, the mathematical model of the GPVGS is firstly established. Secondly, the electrical torque analysis method is used to analyze the influence law of inertia, damping and synchronization characteristics from the physical mechanism perspective. The research finds that the equivalent inertia, damping and synchronization coefficient of the system are determined by the control parameters, structural parameters and steady-state operating point parameters. Changing the control parameters is the simplest and most flexible way to influence the inertia, damping and synchronization ability of the system. The system inertia is influenced by the DC voltage outer loop proportional coefficient Kp and enhanced with the increase of Kp. The damping characteristic of the system is affected by the droop coefficient Dp and weakened with the increase of Dp. The synchronization effect is only controlled by DC voltage outer loop integral coefficient Ki and enhanced with the increase of Ki. In addition, the system dynamic is also affected by the structural parameters such as line impedance X, DC bus capacitance C, and steady-state operating point parameters such as the AC or DC bus voltage level of the system and steady-state operating power (power angle). Finally, the correctness of the above analysis are verified by the simulation and experimental results.

scholarly journals Axial and lateral stiffness of spherical self-balancing fiber reinforced rubber pipes under internal pressure

2021 ◽  
Vol 28 (1) ◽  
pp. 96-106
Author(s):  
Guo-min Xu ◽  
Chang-geng Shuai
Keyword(s):  
Internal Pressure ◽  
Vibration Suppression ◽  
Structural Parameters ◽  
Axial Stiffness ◽  
Lateral Stiffness ◽  
Fiber Reinforced ◽  
Investigation Methods ◽  
Nonlinear Stress ◽  
Relationship Of ◽  
Winding Angle

Abstract Fiber reinforced rubber pipes are widely used to transport fluid at locations requiring flexible connections in pipeline systems. The spherical self-balancing fiber reinforced rubber pipes with low stiffness are drawing attention because of their vibration suppression performance under high internal pressure. In this paper, a theoretical model is proposed to calculate the axial stiffness and lateral stiffness of spherical self-balancing fiber reinforced rubber pipes. The inhomogeneous anisotropy of the reinforced layer and the nonlinear stress-strain relationship of the reinforced fiber are considered in the model. The accuracy of the model is verified by experimental results. Theoretical calculation finds that both the axial and lateral stiffness are influenced significantly by the key structural parameters of the pipe (the axial length, the circumferential radius at the end, the meridional radius, and the initial winding angle). The stiffness can be reduced remarkably with optimal meridional radius and initial winding angle, without any side effect on the self-balance of the pipe. The investigation methods and results presented in this paper will provide guidance for design of fiber reinforced rubber pipes in the future.

scholarly journals MULTI-OBJECTIVE OPTIMIZATION OF SNAKE ROBOT IN SERPENTINE LOCOMOTION

2021 ◽  
Vol 22 (2) ◽  
pp. 364-383
Author(s):  
Md Raisuddin Khan ◽  
Marwan Badran ◽  
Siti Fauziah ◽  
Zulkifly Bin Zainal Abidin
Keyword(s):  
Energy Consumption ◽  
Periodic Pattern ◽  
Pareto Optimal ◽  
Multi Objective Optimization ◽  
Snake Robot ◽  
Multi Objective ◽  
Weighted Sum Method ◽  
Travelling Time ◽  
Simulation Results ◽  
Winding Angle

This paper presents multi-objective optimization for a snake robot with serpentine locomotion. Genetic algorithm (GA) is used to achieve two objectives: minimizing the total travelling time and minimizing the total energy consumption. The effect of initial values of winding angle and acceleration on energy consumption and average speed is depicted. The simulation results show a periodic pattern of the joint torques when the robot maintains a serpenoid curve during travel. Moreover, a Pareto-optimal front was generated for optimal solutions of both of the objectives, while the weighted sum method was used for selecting the best solution. Finally, the simulation results were verified experimentally on an eight-link snake robot considering the limitations of the servomotors used in the experiment. The experimental results with the winding angle of 30° was found as the optimum winding angle that can achieve both objectives of minimizing the energy consumption and the travelling time. ABSTRAK: Kajian ini berkenaan pelbagai-objektif optimum bagi robot ular dengan gerakan serpentin. Algoritma genetik (GA) diguna bagi mencapai dua objektif ini iaitu mengurangkan jumlah masa gerakan dan guna tenaga. Gambaran kesan awal nilai sudut belitan dan pecutan pada guna tenaga dan purata kelajuan dihasilkan. Dapatan simulasi menunjukkan corak berkala tork sendi yang tetap terhasil semasa robot ini berkeadaan lengkung serpenoid ketika bergerak. Tambahan, Pareto-optimal berdepan terhasil bagi solusi optimum pada kedua-dua objektif, sementara kaedah berat campuran digunakan bagi menentukan solusi terbaik. Akhirnya, dapatan simulasi disahkan secara eksperimen pada robot ular lapan-bahagian dengan menimbangkan kekurangan servomotor yang digunakan dalam eksperimen. Dapatan eksperimen menunjukkan sudut belitan 30° adalah sudut belitan optimum bagi kedua-dua objektif iaitu mengurangkan tenaga dan masa gerakan.

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