Suril V. Shah
Other affiliations: Indian Institutes of Technology, Indian Institute of Technology Delhi, McGill University ...read more
Bio: Suril V. Shah is an academic researcher from Indian Institute of Technology, Jodhpur. The author has contributed to research in topics: Robot & Motion planning. The author has an hindex of 11, co-authored 63 publications receiving 377 citations. Previous affiliations of Suril V. Shah include Indian Institutes of Technology & Indian Institute of Technology Delhi.
19 Aug 2013
TL;DR: Three point-to-point path planning strategies are presented, which improve the reactionless operation of the dual-arm robot for capture of tumbling orbiting objects, such as out-ofcommission satellites and space debris.
Abstract: This paper presents strategies for point-to-point reactionless manipulation of a satellite mounted dual-arm robotic system for capture of tumbling orbiting objects, such as out-ofcommission satellites and space debris. Use of the dual-arm robot could be more effective than the single arm when there is no provision for a grapple fixture or the object is tumbling. The dual arms can also provide dexterous manipulation. As the main objective in capture of orbital objects is to move the end-effector from initial position to the grapple point with desired velocity, the task-level reactionless constraints in terms of end-effector velocities are derived. The trajectory planned using these constraints, however, results in several singular points within the robot’s workspace. In order to overcome this shortcoming, three point-to-point path planning strategies are presented, which improve the reactionless operation of the dual-arm robot. The strategies are illustrated by carrying out simulations for a 6-degree-of-freedom (DOF) dual-arm robotic system mounted on a satellite.
TL;DR: In this paper, a legged robot is modeled as a floating-base tree-type system where the foot-ground interactions are represented as external forces and moments, and recursive algorithms for inverse and forward dynamics are proposed by using inter-and intra-modular recursions for the first time.
Abstract: In this paper, a legged robot is modeled as a floating-base tree-type system where the foot-ground interactions are represented as external forces and moments. Dynamic formulation thus obtained is independent of the configuration or state of the legged robot. Framework for dynamic modeling is proposed with the concept of kinematic modules, where each module is a set of serially connected links. Legged robots are then considered to have several kinematic modules, and kinematic constraints among these modules are obtained in a similar way as those between the links. The latter approach turns out to be a special case of the former where each module has only one link. A velocity transformation based approach is used to obtain the minimal-order equations of motion, and module-level analytical expressions for the vectors and matrices appearing in them. Recursive algorithms for inverse and forward dynamics are proposed by using inter- and intra-modular recursions for the first time. Analyses of a planar biped and spatial quadruped are presented using the proposed methodology. Effectiveness of the proposed algorithms to model-based control schemes is also provided.
•14 Dec 2012
TL;DR: The DeNOC matrices of Eq.
Abstract: As reviewed in Chap. 2, Newton-Euler (NE) equations of motion are found to be popular in dynamic formulations. Several methods were also proposed by various researchers to obtain the Euler-Langrage’s form of NE equations of motion. One of these methods is based on velocity transformation of the kinematic constraints, e.g., the Natural Orthogonal Complement (NOC) or the Decoupled NOC (DeNOC), as obtained in Chap. 4. The DeNOC matrices of Eq. (4.28) are used in this chapter to obtain the minimal order dynamic equations of motion that have several benefits.
TL;DR: The recursive dynamics simulator (ReDySim) is a MATLAB-based recursive solver for dynamic analysis of multibody systems that delves upon the decoupled natural orthogonal complement approach originally developed for serial-chain manipulators.
Abstract: Recursive formulations have significantly helped in achieving real-time computations and model-based control laws. The recursive dynamics simulator (ReDySim) is a MATLAB-based recursive solver for dynamic analysis of multibody systems. ReDySim delves upon the decoupled natural orthogonal complement approach originally developed for serial-chain manipulators. In comparison to the commercially available software, dynamic analyses in ReDySim can be performed without creating solid model. The input parameters are specified in MATLAB environment. ReDySim has the capability to incorporate any control algorithm with utmost ease. In this work, the capabilities of ReDySim for solving open-loop and closed-loop systems are shown by examples of robotic gripper, KUKA KR5 industrial manipulator and four-bar mechanism. ReDySim can be downloaded for free from http://www.redysim.co.nr and can be used almost instantly.
TL;DR: The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or her own research.
Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or
01 Jan 1979
TL;DR: In this article, an extension of the present theory of limb coordination for such machines to the case in which the terrain includes regions not suitable for weight-bearing and which must consequently be avoided by the control computer in deciding when and where to successively place the feet of the vehicle.
Abstract: Although the off-road mobility characteristics of wheeled or tracked vehicles are generally recognized as being inferior to those of man and cursorial animals, the complexity of the joint-coordination control problem has thus far frustrated attempts to achieve improved vehicular terrain adaptability through the application of legged locomotion concepts. Nevertheless, the evident superiority of biological systems in this regard has motivated a number of theoretical studies over the past decade which have now reached a state of maturity sufficient to permit the construction of experimental computer-controlled adaptive walking machines. At least two such vehicles are known to have recently demonstrated legged locomotion over smooth hard-surfaced terrain. This paper is concerned with an extension of the present theory of limb coordination for such machines to the case in which the terrain includes regions not suitable for weight-bearing and which must consequently be avoided by the control computer in deciding when and where to successively place the feet of the vehicle. The paper includes a complete problem formalization, a heuristic algorithm for solution of the problem thus posed, and a preliminary evaluation of the proposed algorithm in terms of a computer simulation study.
TL;DR: A new control system that consists of two modules: trajectory planning module (based on trajectory optimization algorithm) and Model Predictive Controller that takes into account the free-floating nature of the satellite-manipulator system is presented.
Abstract: Manipulator mounted on an unmanned satellite could be used for performing orbital capture maneuver in order to repair satellites or remove space debris from orbit. Use of manipulators for such purposes presents unique challenges, as high level of autonomy is required and the motion of the manipulator influences the position and orientation of the manipulator-equipped satellite. This paper presents a new control system that consists of two modules: trajectory planning module (based on trajectory optimization algorithm) and Model Predictive Controller. Both modules take into account the free-floating nature of the satellite-manipulator system. Proposed control system was tested in numerical simulations performed for a simplified planar case. In the first set of simulations Nonlinear Model Predictive Control (NMPC) was used to ensure realization of a square reference end-effector trajectory, while in the second set control system was used for optimizing and then ensuring realization of the trajectory that leads to grasping of the rotating target satellite. Simulations were performed with disturbances and with the assumed non-perfect knowledge of parameters of the satellite-manipulator system. Results obtained with NMPC are better than results obtained with the controller based on the Dynamic Jacobian inverse and with the Modified Simple Adaptive Control (MSAC).
••27 Oct 1988
TL;DR: In this paper, a spatial operator algebra for modeling, control and trajectory design of manipulators is discussed, which is based on linear operators whose domain and range spaces consist of forces, moments, velocities, and accelerations.
Abstract: A recently developed spatial operator algebra for modeling, control and trajectory design of manipulators is discussed. The elements of this algebra are linear operators whose domain and range spaces consist of forces, moments, velocities, and accelerations. The operators themselves are elements in the algebra of linear bounded operators. The effect of these operators when operating on elements in the domain is equivalent to a spatial recursion along the span of a manipulator. Inversion of operators can be efficiently obtained via techniques of spatially recursive filtering and smoothing. The operator algebra provides a high-level framework for describing the dynamic and kinematic behavior of a manipulator and for the corresponding control and trajectory design algorithms. Expressions interpreted within the algebraic framework lead to enhanced conceptual and physical understanding of manipulator dynamics and kinematics. Furthermore, implementable recursive algorithms can be immediately derived from the abstract operator expressions by inspection. Thus, the transition from an abstract problem formulation and solution to the detailed mechanization of specific algorithms is greatly simplified. This paper discusses the analytical formulation of the operator algebra, as well as its implementation in the Ada programming language.
TL;DR: In this article, a lumped-parameter approach for modeling the net and different models of contact dynamics are presented; a continuous compliant approach for the normal contact force and a modified damped bristle model for the friction force are chosen.
Abstract: A proposed method for containing the growth of space debris, which jeopardizes operation of spacecraft, is the active debris removal of massive derelict spacecraft and launcher upper stages by means of tether nets. The behavior of nets in space is not well known; therefore, numerical simulation is needed to gain understanding of deployment and capture dynamics. In this paper, a lumped-parameter approach for modeling the net and different models of contact dynamics are presented. A continuous compliant approach for the normal contact force and a modified damped bristle model for the friction force are chosen. The capability of the developed simulation tool to represent multiple dynamic conditions is demonstrated in this paper, and the results of a deployment dynamics simulation are presented; this reveals a snapping behavior of tension. Simulation of net-based capture of cylindrical debris in microgravity and vacuum conditions is performed with the presented tool. The effect of employing different contact ...