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Sandipan Bandyopadhyay
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Sandipan Bandyopadhyay
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Sandipan Bandyopadhyay
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Bandyopadhyay, Sandipan
Bandyopadhyay, S.
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63 results
Now showing 1 - 10 of 63
- PublicationPosition Kinematics of a 3-RRS Parallel Manipulator(01-01-2016)
;Tetik, Halil ;Kalla, Rohit ;Kiper, GokhanThe 3-RRS parallel manipulator presented in this study comprises of parallel revolute joint axes in each leg. The manipulator is composed of a base and a moving platform which are in the shape of equilateral triangles. Moving platform has two rotational and one translational degrees-of-freedom. This study formulates the forward and inverse kinematics of the parallel manipulator. A 16th order polynomial in terms of one of the passive joint variables is obtained for the forward kinematic analysis. Numerical results and the corresponding pose of the manipulator for inverse and forward kinematics are presented. - PublicationSingularity-free spheres in the position and orientation workspaces of Stewart platform manipulators(01-01-2021)
;Nag, AnirbanThis paper presents the computation of singularity-free regions in the position and orientation workspaces of Stewart platform manipulators (SPMs). Notwithstanding several previous publications in this regard, certain issues persist, such as the unavailability of analytical solutions and the consequent lack of accurate estimates of the numbers of solutions in various cases; the improper use of an incompatible metric while finding such regions inside SO(3) or SE(3). In this paper, the singularity-free regions have been envisaged as spheres in either R3 or SO(3). An analytical formulation for identifying such singularity-free spheres (SFSs) is presented. Several algebraic methods are explored to solve the resulting set of polynomial equations, leading to valuable insights into the numbers of (finite, complex) solutions to this problem, in both the position and the orientation workspaces. A physically meaningful and mathematically sound metric is used while computing the SFS in the orientation workspace. The formulation and computational algorithms have been demonstrated by identifying the SFSs (in R3 as well as SO(3)) for multiple architectures of the SPM through implementations in the C language. - PublicationQuaternion-based backstepping for line-of-sight tracking of satellites using only magnetorquers(01-01-2013)
;Kannapan, Deepti; A new strategy for the design of tracking control laws is presented for line-of-sight (LoS) pointing control of satellites that use only magnetorquers. This strategy makes use of the backstepping approach, and applies to satellites that require the LoS of a single instrument, such as a transmission antenna or camera, to be pointed at a given time, but not both simultaneously. Asymptotic stability of the desired trajectory is proved, provided the target pointing-direction lies outside some critical range. A control law so developed is numerically simulated for a nanosatellite mission scenario to demonstrate feasibility. © 2013 2013 California Institute of Technology. - PublicationA study of Σ2 singularities in the 3-RPS Parallel Manipulator(01-01-2015)
;Kalla, Rohit ;Nurahmi, Latifah; ;Caro, StephaneWenger, PhilippeThis paper presents some analytical results related to the determination of the singular poses of the 3-RPS parallel manipulator at which it gains two degrees of freedom. The forward kinematic univariate (FKU) of the manipulator acquires a special structure at such a pose. All such poses have been identified in the closed-form, using a Stüdy-parameter representation of SE(3), for both the operation modes of the 3-RPS. These results are novel, to the best of the knowledge of the authors, and these have been verified using the traditional method, using the criterion of loss of rank of certain Jacobian matrices. The theoretical results have been illustrated with numerical examples. - PublicationA uniform geometric-algebraic framework for the forward kinematic analysis of 6-6 stewart platform manipulators of various architectures and other related 6-6 spatial manipulators(01-01-2021)
;Nag, Anirban ;V, SafarThis paper presents a generic geometric-algebraic framework to solve the forward kinematic problem (FKP) of 6-6 Stewart platform manipulators (SPM) in which both the fixed and moving platforms can be either planar or non-planar/general. The FKPs of the SPMs having some of these architectures, e.g., one with a planar moving and general fixed platform, have not been solved explicitly in the existing literature, to the best of the knowledge of the authors. Moreover, some of the existing algorithms applicable to some other classes of SPMs are seen to fail in this case. The algorithms proposed in this paper solves the FKP of this class SPMs, and also that of the 6-RSS manipulator, by relating it to the former. Apart from generating these novel results, the algorithm is amenable to fast and reliable implementation in a generic programming language, such as C, and is able to solve a typical FKP in about 0.7 ms on an ordinary PC. The formulation is illustrated via applications to a number of SPMs and 6-RSS manipulators of different architectures. - PublicationA Deterministic Attitude Estimation Using a Single Vector Information and Rate Gyros(01-10-2015)
;Vinod, Abraham P.; ; Muralidharan, VijayThis paper proposes a deterministic estimator for the estimation of the attitude of a rigid body. A deterministic estimator uses a minimal set of information and does not try to minimize a cost function or fit the measurements into a stochastic process. The proposed estimator obtains the attitude estimation utilizing only the properties of the rotational group SO(3). The information set required by the proposed estimator is a single vector information and rate gyro readings. For systems in which one of the rotational freedom is constrained, the proposed estimator provides an accurate estimate of the reduced attitude. The performance of the algorithm is verified on different experimental testbeds. - PublicationA homotopy-based method for the synthesis of defect-free mechanisms satisfying secondary design considerations(01-03-2019)
;Baskar, AravindThis paper presents a methodology to synthesise mechanisms free of kinematic defects in precision-point problems. The considerations for obtaining defect-free mechanisms are embedded in the mathematical formulation of the exactsynthesis procedure. However, this requires that at least one less target point is specified than the maximum number that the mechanism can reach exactly. An example from the existing literature of a four-bar linkage is studied. Identification of the branch-transition and the circuit-transition linkages enables the characterisation of the feasible ranges of the solutions in the design parameter space. These linkages are identified by formulating appropriate systems of polynomial equations and solving them. A root-generation algorithm reported in literature called cyclic coefficient-parameter continuation is employed to establish the finite root-count of these systems. Once the kinematic defect-free branch/circuit-transition linkages are identified, other design objectives can be brought into consideration to find optimal solutions in the feasible design ranges using design parameter continuation starting with these linkages. The results obtained demonstrate certain advantages afforded by proposed methodology over the existing exact and optimal methods for the synthesis of mechanisms. - PublicationDual-loop control for backlash correction in trajectory-tracking of a planar 3-RRR manipulator(01-01-2011)
;Agarwal, Abhishek ;Nasa, ChamanThe presence of backlash in the gearheads is an inherent problem in manipulators using geared motors. This paper looks at a potential solution to this problem via the implementation of a dual-loop control strategy, in which feedback is taken from the motors as well as the end-effector of the manipulator. Using the redundant sensed information, the actual error in the joint-space is computed and used to rectify the desired trajectory for the joint-space trajectory-tracking control scheme. Experiments done on a 3-RRR planar parallel manipulator show significant improvement in the tracking performance due to the introduction of dual-loop control scheme. - PublicationA Comparative Study of the Configuration-Space and Actuator-Space Forward Dynamics of Closed-Loop Mechanisms Using the Lagrangian Formalism(01-01-2019)
;Nag, AnirbanThis paper presents a comparative study between two related methods of formulating the equations of motion, within the Lagrangian framework, for closed-loop mechanisms. Such mechanisms encounter singularities not only at the boundaries of their workspaces, but also inside the workspaces. The latter kind of singularities are detrimental to the operation of the mechanisms and may lead to their mechanical failure. The primary objective of the paper is to investigate the ways in which these singularities impact the two formulations, and to establish a relation between them. A planar five-bar mechanism is used to illustrate that the singularities appearing in one formulation is a subset of those appearing in the other formulation. The second objective is to provide a qualitative analysis of the time-complexities of the respective formulations. A planar five-bar and the Stewart platform manipulator are used to study and compare the computational costs incurred in either of the formulations. - PublicationAnalytical determination of the proximity of two right-circular cylinders in space(01-08-2016)
;Agarwal, Saurav ;Srivatsan, Rangaprasad ArunThis paper presents a novel analytical formulation for identifying the closest pair of points lying on two arbitrary cylinders in space, and subsequently the distance between them. Each cylinder is decomposed into four geometric primitives. It is shown that the original problem reduces to the computation of the shortest distance between five distinct combinations of these primitives. Four of these subproblems are solved in closed form, while the remaining one requires the solution of an eight-degree polynomial equation. The analytical nature of the formulation and solution allows the identification of all the special cases, e.g., positive-dimensional solutions, and the curve of intersection when the cylinders interfere. The symbolic precomputation of the results leads to a fast numerical implementation, capable of solving the problem in about 50 ls (averaged over 1×106 random instances of the most general case) on a standard PC. The numerical results are verified by repeating all the calculations in a general-purpose commercial CAD software. The algorithm has significant potential for applications in the various aspects of robotics and mechanisms, as their links can be modeled easily and compactly as cylinders. This makes tasks such as path planning, determination of the collision-free workspace, etc., computationally easier.