BITS Faculty Publications
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Item Screening of factors influencing the performance of manipulator using combined array design of experiment approach(Elsevier, 2009-06) Rout, Bijay KumarA robot must manipulate objects with high accuracy and repeatability to perform precise tasks. However, deviation in performance is attributed to uncertainties and improper selection of control, noise, and process factors. The information regarding the effect of these factors on performance is almost non-existent. A probabilistic approach has been used to model and simulate the performance of manipulator. The combined array fractional factorial design of experiment approach has been employed to identify the significant factors and their interactions. This approach helps in screening of the manipulator factors and focus on those that are important. To explore further, two indices, viz. link length ratio and link mass ratio, have been proposed and impact of these indices on manipulator performance is investigated. A two degree of freedom (2-DOF) RR planar manipulator performing a task with cubic and quintic trajectory has been used to illustrate the approach. It has been observed that the statistically significant factors are different for different tasks in workspace. It has also been observed that for the same task, factors responsible for performance variations are different for cubic and quintic trajectories. Finally, it has been demonstrated that the link length ratio change has significant influence on performance compared to link mass ratio.Item Optimal design of manipulator parameter using evolutionary optimization techniques(CUP, 2009-07) Rout, Bijay KumarA robot must have high positioning accuracy and repeatability for precise applications. However, variations in performance are observed due to the effect of uncertainty in design and process parameters. So far, there has been no attempt to optimize the design parameters of manipulator by which performance variations will be minimum. A modification in differential evolution optimization technique is proposed to incorporate the effect of noises in the optimization process and obtain the optimal design of manipulator, which is insensitive to noises. This approach has been illustrated by selecting optimal parameter of 2-DOF RR planar manipulator and 4-DOF SCARA manipulator. The performance of proposed approach has been compared with genetic algorithm with similar modifications. It is observed that the optimal results are obtained with lesser computations in case of differential evolution technique. This approach is a viable alternative for costly prototype testing, where only kinematic and dynamic models of manipulator are dealt with.Item Tolerance design of robot parameters using Taguchi method(Elsevier, 2006-11) Rout, Bijay KumarA robotic arm must be able to manipulate objects with high accuracy and repeatability. As with every physical system, there are number of noise factors cause uncertainty in the performance. A probabilistic approach has been used to model, the otherwise difficult to model, noise effects. This paper presents the approach utilised in selection of tolerance specification of robot kinematic and dynamic parameters using experimental design technique for reduction of performance variations. The concept of inner and outer orthogonal arrays proposed by Taguchi is employed to identify the significant parameters and select the optimal tolerance range. The performance measure, i.e. signal-to-noise ratio is utilised to validate by Monte Carlo simulations and to complement above study individual parameter tolerance sensitivity are investigated. To provide insight to investigation, parameter sensitivity maps are plotted. The tolerance specification selection methodology of a manipulator is illustrated by taking 2-DOF RR planar manipulator with payloadItem Parametric design optimization of 2-DOF R–R planar manipulator—A design of experiment approach(Elsevier, 2008-04) Rout, Bijay KumarThis work illustrates simulation approach for optimizing the parametric design and performance of a 2-DOF R–R planar manipulator. Using dynamic and kinematic models of a manipulator different performance measures for the manipulator are obtained for different combination of parameters with effect of noise incorporated to imitate the real time performance of the manipulator. A novel approach has been proposed to model, the otherwise difficult to model, noise effects. The data generated during simulation for various parameter combinations are utilized to analyze the statistical significance of kinematic and dynamic parameters on performance of manipulator using ANOVA technique. The parameter combinations, which give optimum performance measures obtained for different points in workspace, are compared and reported.