Tolerance Analysis of a Robot Manipulator Having Uncertainties in Joint Clearance and Axis Orientation

2007 ◽  
Author(s):  
Dong Hwan Choi ◽  
Se Jeong Lee ◽  
Jonathan A. Wickert ◽  
Hong Hee Yoo
Keyword(s):  
Robot Manipulator ◽  
Statistical Design ◽  
Tolerance Analysis ◽  
Joint Clearance ◽  
Design Parameters ◽  
Positional Error ◽  
Link Length ◽  
Axis Orientation ◽  
Manufacturing Tolerances ◽  
Clearance Model

The operating positional error of a robot manipulator, which develops inevitably because of manufacturing tolerances and assembly clearances, is preferentially maintained within a certain range in order to achieve an acceptable level of performance and accuracy. Because additional cost is incurred when manufacturing tolerances are tightened, an alternative design strategy maximizes the tolerances (so as to reduce the cost) while minimizing positioning error (to satisfy a performance requirement). In this paper, a new joint clearance model is developed for spatial mechanisms that incorporate revolute joints, which in turn are subjected to specified tolerance or uncertainty in the orientation of their axes. Statistical design parameters related to variations of link length and joint axis orientation are identified from the clearance model. The statistical influence of the design parameters on the robot manipulator’s response is investigated through a general multibody dynamics sensitivity formulation. The method offers substantial improvement in computational efficiency when compared to the Monte Carlo procedure. The uncertainty in orientation of a revolute joint’s axis influences the positioning accuracy of the robot manipulator’s response to a greater degree than does uncertainty in the length of a link.

Manufacturing Tolerance Analysis of a Robot Manipulator’s Joint Axis Orientation Employing Single Monte-Carlo Simulation

2006 ◽  
Author(s):  
Dong Hwan Choi ◽  
Hong Hee Yoo
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Robot Manipulator ◽  
Computing Time ◽  
Tolerance Analysis ◽  
Manufacturing Cost ◽  
Axis Orientation ◽  
Manufacturing Tolerance ◽  
Design Engineers ◽  
Joint Axis

The operation error of a robot manipulator that occurs inevitably due to the manufacturing tolerance needs to be controlled within a certain range to achieve proper performance. The reduction of manufacturing tolerance, however, increases the manufacturing cost in return. Therefore, system design engineers try to solve the problem of maximizing the tolerance to reduce the manufacturing cost while minimizing the operation error to satisfy the performance requirement. In the present study, a revolute joint model considering the variation of joint axis orientation due to joint clearance is employed to perform a tolerance analysis of the robot manipulator operation. This paper presents a hybrid method which employs the sensitivity-based analytic method and the single Monte-Carlo simulation. The proposed method provides rapid implementation and the accurate statistical properties using the only single integration or single iteration for one sample set, whereas the Monte-Carlo method necessitates integrations as the number of samples and cases. Significant reduction of computing time can be achieved with the proposed method. The present method is especially effective if sensitivity information is hard to be obtained for the analysis.

Investigation of Positional Error in Two Degree of Freedom Mechanism With Joint Clearance

2012 ◽  
Vol 4 (1) ◽  
Author(s):  
H. P. Jawale ◽  
H. T. Thorat
Keyword(s):  
Closed Loop ◽  
Robotic Manipulators ◽  
Simple Approach ◽  
Joint Clearance ◽  
Positional Error ◽  
Link Length ◽  
Positional Accuracy ◽  
Positional Analysis ◽  
Closed Chain ◽  
Two Degree Of Freedom

Closed chain mechanisms are used as robotic manipulators with special features. A planar two-DOF closed loop mechanism provides desired position of an end effecter in a confined workspace with two input motions. Position of end effecter depends on various factors including joint clearance. Positional accuracy forms important parameter for kinematic analysis of mechanism. This paper presents simple approach for quantifying error due to joint clearance in a two-DOF mechanism. Generalized scheme for positional deviation with and without clearance at joint is presented. Orientation of clearance links for maximum positional error is identified. Error at various positions is quantified in relation with clearance link length. Computer programming is used as a tool to workout positional analysis of mechanism. Results show that error is independent of magnitude of clearance, however, a function of location of end effecter in workspace.

A DOE- and Kriging-Based Model for Studying on the Dynamics of Multibody Mechanical Systems With Revolute Joint Clearance

2013 ◽  
Author(s):  
Zhenhua Zhang ◽  
Liang Xu ◽  
Paulo Flores ◽  
Hamid M. Lankarani
Keyword(s):  
Simulation Model ◽  
Mechanical System ◽  
Contact Force ◽  
Design Parameter ◽  
Joint Clearance ◽  
Design Parameters ◽  
Force Model ◽  
Revolute Joint ◽  
Clearance Joint ◽  
Contact Force Model

Over the last two decades, extensive work has been conducted on dynamic effect of joint clearances in multibody mechanical systems. In contrast, little work has been devoted to optimizing the performance of these systems. In this study, analysis of revolute joint clearance is formulated in term of a Hertzian-based contact force model. For illustration, the classical slider-crank mechanism with a revolute clearance joint at the piston pin is presented, and a simulation model is developed using the analysis/design code MSC.ADAMS. The clearance is modeled as a pin-in-a-hole surface-to-surface dry contact, with appropriate contact force model between the joint and bearing surfaces. Different simulations are performed to demonstrate the influence of the joint clearance size and the input crank speed on the dynamic behavior of the system with the clearance joint. An innovative design-of-experiment (DOE)-based method for optimizing the performance of a mechanical system with the revolute joint clearance for different ranges of design parameters is then proposed. Based on the simulation model results from sample points, which are selected by a Latin hypercube sampling (LHS) method, a polynomial function Kriging meta-model is established instead of the actual simulation model. The reason for development and use of the meta-model is to bypass computationally intensive simulations of a computer model for different design parameter values in place of a more efficient and cost-effective mathematical model. Finally, numerical results obtained from two application examples, considering the different design parameters, including the joint clearance size, crank speed, and contact stiffness, are presented for further analyzing the dynamics of the revolute clearance joint in a mechanical system. This allows for predicting the influence of design parameter changes, in order to minimize contact forces, accelerations, and power requirements due to the existence of joint clearance.

Vibration Analysis of Rotor-Fluid Film Bearing System Using Monte Carlo Method

2010 ◽  
Author(s):  
Zhengkai Zhang ◽  
Youyun Zhang ◽  
Yongsheng Zhu
Keyword(s):  
Monte Carlo ◽  
Vibration Analysis ◽  
Monte Carlo Analysis ◽  
Working Environment ◽  
Fluid Film ◽  
Design Parameters ◽  
Rotor Vibration ◽  
Design And Manufacturing ◽  
Manufacturing Tolerances ◽  
Bearing System

The rotor-fluid film bearing systems are widely used in machinery due to their small size, low price, and capability of carrying load. However, if its design and manufacturing is inappropriate, the use of rotor-fluid film bearing system will suffers from some problem such as violent vibration. Although the checking calculation has been carried out during the design process, nominal value of design parameters is usual used to prognosis the vibration characteristics of rotor-fluid film bearing system. However, in practice, these parameters always vary within a certain range due to manufacturing tolerances and variation of working environment. In this paper, a model for simulating the performance of rotor-fluid film bearing system has been established. Monte Carlo analysis was performed to evaluate the effects of manufacturing tolerances and variation of working environment on the rotor vibration. In the end, a uncertainty analysis is carried out to demonstrate which of the factors has the greatest effect on the rotor vibration at different rotational speed.

Simulation Study of Permanent Magnetic Actuation for a Hydraulic Valve With Hysteresis Response Behavior

2020 ◽  
Author(s):  
Matthias Scherrer ◽  
Erwin Hauser ◽  
Rudolf Scheidl
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Ferromagnetic Material ◽  
Hydraulic Cylinder ◽  
Performance Criteria ◽  
Design Parameters ◽  
Magnetic Actuation ◽  
Magnetic Forces ◽  
Manufacturing Tolerances ◽  
Hysteretic Response

Abstract For the realization of compact and lightweight digital hydraulic cylinder drives for exoskeleton actuation the hydraulic binary counter concept was proposed. This counter principle is based on hydraulically piloted switching valves which feature a hysteretic response with respect to the pilot pressure. In first prototypes of that counter bistable mechanical buckling beams realized the hysteretic response. Their performance suffered from high friction in the hinges and high local stresses. Furthermore, they require tight manufacturing tolerances not only of themselves but also of their bearing structure. In this paper, the usage of a permanent magnet concept to realize the hysteresis function in an alternative way is studied. The valve spool is made of a ferromagnetic material and is attracted or repelled by a permanent magnet made of a Neodymium-Iron-Bor. The expected benefits are lower friction, lower demands on manufacturing tolerances, and an easier assembly of the valve. To find an advantageous embodiment of this functioning principle ring or disc shaped magnets of different sizes are analyzed. The magnetic forces exhibited by these different magnetic circuit designs are simulated with the Magnetic Finite Element code ‘FEMM’. The quasi-static magnetic forces at different spool positions are computed. Magnetic saturation and remanence are considered in this analysis. The aim is to achieve the required force on the piston and, thus, ensure the valve’s functionality. At the same time, however, the valve should be designed as compact and light as possible. The Finite element simulations are compared with an analytical model which provides a compact understanding of the influence of the design parameters on the functional and non functional performance criteria.

Tolerance Analysis and Synthesis for Composite Assemblies of Resin Transfer Molded Components

Manufacturing ◽  
2003 ◽  
Author(s):  
Chensong Dong ◽  
Chuck Zhang ◽  
Zhiyong Liang ◽  
Ben Wang
Keyword(s):  
Composite Structures ◽  
Dimensional Accuracy ◽  
Tolerance Analysis ◽  
Process Models ◽  
Design Parameters ◽  
Element Analysis ◽  
Control Dimension ◽  
And Control ◽  
Prediction Approach ◽  
Variation Model

With the increasing demand for composite products to be affordable, net-shaped and efficiently assembled, tight dimension tolerance is critical. Due to lack of accurate process models, dimension analysis and control for resin transfer molding (RTM) processes are often performed using trial-and-error approaches based on engineers’ experiences or previous production data. Such approaches are limited to specific geometry and materials and often fail to achieve the required dimensional accuracy in the final products. This paper presents an innovative dimension variation prediction approach. First a dimension variation model was developed based on process simulation, the classical laminate theory (CLT) and finite element analysis (FEA). The FEA-based dimension variation model was validated against experimental data. The deformations of common features in typical composite structures were analyzed using the FEA-based dimension variation model. Design parameters were identified and the regression-based dimension variation model was developed. The model provides a fast, practical and proactive tool to predict and control dimension variations in RTM processes. The structural tree method (STM) is presented for design optimization and tolerance analysis/synthesis of composite assemblies.

Response Surface Models for Analyzing Planing Hull Motions in a Vertical Plane

2014 ◽  
Author(s):  
Tanvir Mehedi Sayeed ◽  
Leonard M. Lye ◽  
Heather Peng
Keyword(s):  
High Speed ◽  
Uniform Design ◽  
Vertical Plane ◽  
Statistical Design ◽  
Surrogate Models ◽  
Center Of Gravity ◽  
Design Parameters ◽  
Strip Theory ◽  
Calm Water ◽  
Sinkage And Trim

A non-linear mathematical model, Planing Hull Motion Program (PHMP) has been developed based on strip theory to predict the heave and pitch motions of planing hull at high speed in head seas. PHMP has been validated against published model test data. For various combinations of design parameters, PHMP can predict the heave and pitch motions and bow and center of gravity accelerations with reasonable accuracy at planing and semi-planing speeds. This paper illustrates an application of modern statistical design of experiment (DOE) methodology to develop simple surrogate models to assess planing hull motions in a vertical plane (surge, heave and pitch) in calm water and in head seas. Responses for running attitude (sinkage and trim) in calm water, and for heave and pitch motions and bow and center of gravity accelerations in head seas were obtained from PHMP based on a multifactor uniform design scheme. Regression surrogate models were developed for both calm water and in head seas for each of the relevant responses. Results showed that the simple one line regression models provided adequate fit to the generated responses and provided valuable insights into the behaviour of planing hull motions in a vertical plane. The simple surrogate models can be a quick and useful tool for the designers during the preliminary design stages.

Accuracy analysis and optimization of an extendible support structure with joint clearances

2020 ◽  
pp. 095440622097305
Author(s):  
Jianzhong Ding ◽  
Chunjie Wang
Keyword(s):  
Monte Carlo ◽  
Reduction Method ◽  
Global Sensitivity Analysis ◽  
Angular Error ◽  
Joint Clearance ◽  
Design Parameters ◽  
Support Structure ◽  
Quasi Monte Carlo ◽  
Joint Clearances ◽  
Independent Parameters

An extendible support structure (ESS) used for unfolding and supporting the antenna array of the Synthetic Aperture Radar (SAR) satellite is reviewed and modeled in this paper. The structure is parameterized by calibrating 12 independent parameters, and following which, angular accuracy of the ESS with joint clearances is modeled. The maximum angular error is obtained by the particle swarm optimization (PSO) and validated by the Monte Carlo simulation. A novel error reduction method is then proposed to improve the accuracy of the structure. In the proposed method, the uncertainty of the joint clearance is eliminated using force constraints by adding small torsional springs. Various joint clearance models with force constraints are proposed to obtain the optimal spring allocation, and based on which, the angular error is further reduced by optimizing the structure of the ESS. The Quasi-Monte-Carlo-based Sobol method for global sensitivity analysis is used to select the design parameters for optimization. Finally, the angular error is greatly reduced.

Application of statistical techniques in modeling and optimization of a snake robot

Robotica ◽  
2012 ◽  
Vol 31 (4) ◽  
pp. 623-641 ◽  
Author(s):  
Hadi Kalani ◽  
Alireza Akbarzadeh ◽  
Hossein Bahrami
Keyword(s):  
Energy Consumption ◽  
Statistical Design ◽  
Optimization Techniques ◽  
Design Parameters ◽  
Snake Robot ◽  
Robot Performance ◽  
And Performance ◽  
Development Analysis ◽  
Curvilinear Regression ◽  
Range Of Values

SUMMARYThis paper provides a general framework based on statistical design and Simulated Annealing (SA) optimization techniques for the development, analysis, and performance evaluation of forthcoming snake robot designs. A planar wheeled snake robot is considered, and the effect of its key design parameters on its performance while moving in serpentine locomotion is investigated. The goal is to minimize energy consumption and maximize distance traveled. Key kinematic and dynamic parameters as well as their corresponding range of values are identified. Derived dynamic and kinematic equations of n-link snake robot are used to perform simulation. Experimental design methodology is used for design characterization. Data are collected as per full factorial design. For both energy consumption and distance traveled, logarithmic, linear, and curvilinear regression models are generated and the best models are selected. Using analysis of variance, ANOVA, effects of parameters on performance of robots are determined. Next, using SA, optimum parameter levels of robots with different number of links to minimize energy consumption and maximize distance traveled are determined. Both single and multi-criteria objectives are considered. Webots and Matlab SimMechanics software are used to validate theoretical results. For the mathematical model and the selected range of values considered, results indicate that the proposed approach is quite effective and efficient in optimization of robot performance. This research extends the present knowledge in this field by identifying additional parameters having significant effect on snake robot performance.

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