Swaminath Venkateswaran - Academia.edu (original) (raw)

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Papers by Swaminath Venkateswaran

Cornell University - arXiv, Jun 3, 2022

Journal of Mechanisms and Robotics

This study presents an optimization approach for the design of a piping inspection robot. A rigid... more This study presents an optimization approach for the design of a piping inspection robot. A rigid bio-inspired piping inspection robot that moves like a caterpillar was designed and developed at LS2N, France. By the addition of tensegrity mechanisms between the motor modules, the mobile robot becomes flexible to pass through the bends. However, the existing motor units prove to be oversized for passing through pipe bends at 90 deg. Thus, three cascading optimization problems are presented in this article to determine the sizing of robot assembly that can overcome such pipe bends. The first problem deals with the identification of design parameters of the tensegrity mechanism based on static stability. Followed by that, in the second problem, the optimum design parameters of the robot modules are determined for the robot assembly without the presence of leg mechanisms. The third problem deals with the determination of the size of the leg mechanism for the results of the two previous ...

Advances in Mechanism and Machine Science, 2019

The application of robots for the inspection of pipelines are of greater significance in industri... more The application of robots for the inspection of pipelines are of greater significance in industries such as nuclear, chemical and sewage. The major problem in the design of these robots lies in the selection of a suitable locomotion principle, selection of an articulation unit that facilitates the robot to pass through pipe bends and management of cables. In this context, the design of a new bio-inspired piping inspection robot that resembles an elephant trunk has been presented. With the help of leg mechanisms and actuators, a caterpillar locomotion is used within this trunk for establishing adaptive contact points with the walls of pipeline. For the passage through bends and junctions, several case studies of existing researches have been taken into account for the design of an articulation unit. Two solutions, (i) a passive tensegrity structure and (ii) an active tensegrity structure have been proposed for the robot to pass through pipe bends and junctions. A detailed design analysis of the passive solution that uses a universal joint has been presented in this article.

New Trends in Mechanism and Machine Science, 2020

This paper deals with the joint space and workspace analysis of a two degree of freedom spherical... more This paper deals with the joint space and workspace analysis of a two degree of freedom spherical parallel mechanism designed to be used to handle an endoscope. This mechanism is composed of the three legs (2USP-U) to connect the base to a moving platform. As the manipulator can get up to six solutions to the direct kinematic problem (DKP) in four aspects, non-singular assembly modes changing trajectories may exist. The aim of the paper is to check whether a regular workspace centred on home pose can be defined in such a way that no such trajectory exists in this workspace.

Mechanism and Machine Theory, 2021

During Otologic surgery, and more broadly during microsurgery, the surgeon encounters several dif... more During Otologic surgery, and more broadly during microsurgery, the surgeon encounters several difficulties due to the confined spaces and micro-manipulations. The purpose of the paper is to design a robot with a prescribed regular workspace shape to handle an endoscope to assist the Otologic surgery. A spherical parallel mechanism with two degrees of freedom is analysed in its design parameter space. This mechanism is composed of three legs (2USP-U) to connect the base to a moving platform connected to a double parallelogram to create a remote center of motion (RCM). Its kinematic properties, i.e. the singularity locus and the number of direct kinematic solutions, are investigated. For some design parameters, non-singular assembly modes changing trajectories may exist and have to be investigated inside the prescribed regular workspace shape. Two sets of design parameters are presented with their advantages and disadvantages.

This article presents an optimization approach for the design of an inspection robot that can mov... more This article presents an optimization approach for the design of an inspection robot that can move inside variable diameter pipelines having bends and junctions. The inspection robot uses a mechanical design that mimics the locomotion of a caterpillar. The existing prototype developed at LS2N, France is a rigid model that makes it feasible for working only inside straight pipelines. By the addition of a tensegrity mechanism between motor units, the robot is made reconfigurable. However, the motor units used in the prototype are oversized to pass through pipe bends or junctions. An optimization approach is employed to determine the dimensions of motors and their associated leg mechanisms that can overcome such bends. Two optimization problems are defined and solved in this article. The first problem deals with the determination of motor sizing without leg mechanisms. The second problem deals with the determination of sizing of the leg mechanism with respect to the dimensions of motor...

As a part of a project with AREVA, an inspection robot for 50-94 mm diameter range pipelines have... more As a part of a project with AREVA, an inspection robot for 50-94 mm diameter range pipelines have been developed. By using leg mechanisms, DC motors, spindle drive, and control boards, the robot accomplishes the locomotion of a caterpillar. Two algorithms can be classified for the control of this robot via Displacement control algorithm and Force control algorithm. The former deals with the estimation of the position of a robot inside a known environment and it requires sensors for identifying position as well as for initiation procedures. In the case of force control, the algorithm is highly suitable for a robot that moves inside an unknown or closed environment. Using a BeagleBone (BB) black board, the force control algorithm is developed for the inspection robot under study. As the robot works inside pipelines of unknown diameters, the reconfigurable pins of BB black are employed to apply a voltage in order to achieve the desired clamping force for having contact with pipeline wa...

This article analyzes the singularities and workspace of two tensegrity mechanisms that employ a ... more This article analyzes the singularities and workspace of two tensegrity mechanisms that employ a passive universal joint and either three or four tension springs. These two architectures are correlated to 3-SPS-U and 4-SPS-U parallel mechanisms for determining their geometric equations. By fixing the limits of prismatic joints, the workspace for the mechanisms is generated and the parallel singularities are analyzed. Based on the singularity boundaries obtained from the workspace, the joint limits are modified to generate the maximal singularity free workspaces for both the architectures. A comparison is done based on the tilt limits obtained from the workspace of the mechanisms. The mechanism with the maximum tilt limits is implemented for a piping inspection robot to pass through pipe bends and junctions.

Volume 8B: 45th Mechanisms and Robotics Conference (MR), 2021

This article presents the actuation strategy of a 2-DOF tensegrity type mechanism that employs th... more This article presents the actuation strategy of a 2-DOF tensegrity type mechanism that employs three tension springs and a passive universal joint. This mechanism is proposed to be incorporated as an articulation unit for a piping inspection robot in order to overcome pipe bends and junctions. In the event of a junction, external actuations are required to allow the mechanism as well as the robot to follow a certain direction. Using DC-motors coupled with encoders, experiments are carried out on a test bench of the tensegrity mechanism. The actuation of the mobile platform is performed using cables that pass through each spring. By correlating the architecture to a 3-SPS-U parallel mechanism, the singularity-free workspace of the mechanism is analyzed to identify the tilt limits. A closed-loop PID controller is implemented using a microcomputer to perform a linear trajectory within the singularity-free workspace. The Inverse Kinematic Problem (IKP) is solved by passing input tilt an...

Robotics, 2019

Piping inspection robots are of greater importance for industries such as nuclear, chemical and s... more Piping inspection robots are of greater importance for industries such as nuclear, chemical and sewage. Mechanisms having closed loop or tree-like structures can be employed in such pipelines owing to their adaptable structures. A bio-inspired caterpillar type piping inspection robot was developed at Laboratoire des Sciences du Numérique de Nantes (LS2N), France. Using DC motors and leg mechanisms, the robot accomplishes the locomotion of a caterpillar in six-steps. With the help of Coulomb’s law of dry friction, a static force model was written and the contact forces between legs of robot and pipeline walls were determined. The actuator forces of the DC motors were then estimated under static phases for horizontal and vertical orientations of the pipeline. Experiments were then conducted on the prototype where the peak results of static force analysis for a given pipe diameter were set as threshold limits to attain static phases inside a test pipeline. The real-time actuator forces...

Mechanism and Machine Theory, 2019

This paper presents the self-motion conditions of the 3-PPPS parallel robot with an equilateral m... more This paper presents the self-motion conditions of the 3-PPPS parallel robot with an equilateral mobile platform and an equilateral-shaped base. The study of the direct kinematic model shows that this robot admits self-motion of the Cardanic type as the 3-RPR planar parallel robot where the first revolute joint of each leg is actuated or the PamINSA parallel robot. This property explains why the direct kinematic model admits an infinite number of solutions in the center of the workspace but has never been studied until now. The condition of this singularity is described and the location of the self-motion in the workspace with respect to all the singularities is then presented. The quaternion parameters are used to represent the singularity surfaces and the self-motion conditions in the workspace.

Procedia CIRP, 2018

The piping inspection for security or sealing checking is an important challenge when the interna... more The piping inspection for security or sealing checking is an important challenge when the internal diameter of the pipe is small with respect to its length. Some mechanisms using closed loops are able to generate contact forces and deployable structures. By using bio-inspired design, we present a mechanism which is able to move inside pipes by mimicking the motion of a caterpillar. The mechanism is composed of three sections, one for the motion and two with legs that are attached with the inner part of the pipe. A compliant mechanism is proposed to add mobility between the three sections of the robot in order to cross the singularity of the pipe. The results coming from a multi-objective optimization process is used to set the geometric and kinematic parameters of the mechanism taking into account the environmental and design constraints. A mechatronic system is proposed that uses industrial components namely DC motors, ball-screws and servo controllers which can be inserted in the pipe. For horizontal and vertical motions, the contact forces and the motor torques are computed to check the feasibility of the clamping. A prototype made at Laboratoire des Sciences du Numérique de Nantes (LS2N) is used to show the behavior of this concept for slow motions.