Imperial College London

Dr Thrishantha Nanayakkara

Faculty of EngineeringDyson School of Design Engineering

Reader in Design Engineering and Robotics
 
 
 
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Contact

 

+44 (0)20 7594 0965t.nanayakkara Website CV

 
 
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Location

 

Dyson BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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48 results found

Cianchetti M, Ranzani T, Gerboni G, Nanayakkara T, Althoefer K, Dasgupta P, Menciassi Aet al., 2014, Soft Robotics Technologies to Address Shortcomings in Today's Minimally Invasive Surgery: The STIFF-FLOP Approach, SOFT ROBOTICS, Vol: 1, Pages: 122-131, ISSN: 2169-5172

JOURNAL ARTICLE

Konstantinova J, Li M, Mehra G, Dasgupta P, Althoefer K, Nanayakkara Tet al., 2014, Behavioral Characteristics of Manual Palpation to Localize Hard Nodules in Soft Tissues, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 61, Pages: 1651-1659, ISSN: 0018-9294

JOURNAL ARTICLE

, 2014, Passive dynamics of high frequency bat wing flapping with an anisotropic membrane

© 2014 IEEE. We investigate how unmanned aerial vehicles (UAVs) with flexible wings can be designed to exploit the aeroelasticity of wing deformation that is present in bat wings, with a view to improve the efficiency of flight. We constructed a robotic bat wing with fully passive elastic wing-folding properties. The robotic wing is powered by a gearbox running two synchronised motors, effectively providing one degree of motion: the upstroke and down-stroke of the wing. Through numerical simulations and setup experiments, we observed that by integrating a span-wise elastic network into the bat wing, we were able to achieve passive wing-folding that mimics the 8-shape wing-folding seen in bats' high speed flight. This way, we were able to reduce the complexity and additional actuation associated with wing-folding in a robotic wing.

CONFERENCE PAPER

, 2014, Efficient break-away friction ratio and slip prediction based on haptic surface exploration, IEEE Transactions on Robotics, Vol: 30, Pages: 203-219, ISSN: 1552-3098

The break-away friction ratio (BF-ratio), which is the ratio between friction force and the normal force at slip occurrence, is important for the prediction of incipient slip and the determination of optimal grasping forces. Conventionally, this ratio is assumed constant and approximated as the static friction coefficient. However, this ratio varies with acceleration rates and force rates applied to the grasped object and the object material, which lead to difficulties in determining optimal grasping forces that avoid slip. In this paper, we propose a novel approach based on the interactive forces to allow a robotic hand to predict object slip before its occurrence. The approach only requires the robotic hand to have a short haptic surface exploration over the object surface before manipulating it. Then, the frictional properties of the finger-object contact can be efficiently identified, and the BF-ratio can be real-time predicted to predict slip occurrence under dynamic grasping conditions. Using the predicted BF-ratio as a slip, threshold is demonstrated to be more accurate than using the static/Coulomb friction coefficient. The presented approach has been experimentally evaluated on different object surfaces, showing good performance in terms of prediction accuracy, robustness, and computational efficiency. © 2013 IEEE.

JOURNAL ARTICLE

Jiang A, Aste T, Dasgupta P, Althoefer K, Nanayakkara Tet al., 2014, GRANULAR JAMMING WITH HYDRAULIC CONTROL, ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE), Publisher: AMER SOC MECHANICAL ENGINEERS

CONFERENCE PAPER

Jiang A, Adejokun S, Faragasso A, Althoefer K, Nanayakkara T, Dasgupta Pet al., 2014, The granular jamming integrated actuator, International Conference on Advanced Robotics and Intelligent Systems (ARIS), Publisher: IEEE, Pages: 12-17, ISSN: 2374-3255

CONFERENCE PAPER

, 2014, Implementation of tactile sensing for palpation in robot-assisted minimally invasive surgery: A review, IEEE Sensors Journal, Vol: 14, Pages: 2490-2501, ISSN: 1530-437X

Robot-assisted minimally invasive surgery (RMIS) made it possible to perform a number of medical manipulations with reduced patient trauma and better accuracy. Various devices, including tactile sensors, have been developed in recent years to enhance the quality of this procedure. The objective of this paper is to review the latest advancements and challenges in the development of tactile sensing devices designed for surgical applications. In particular, the focus is on palpation and probing devices that can be potentially used in RMIS. In addition, we explore the aspects that should be taken into account when designing tactile sensors for RMIS, incorporating biological inspiration of tactile sensing, features of manual palpation, requirements of RMIS. We provide an overview of recommendations for the development of tactile sensing devices, especially in the context of RMIS. © 2001-2012 IEEE.

JOURNAL ARTICLE

, 2013, Force-velocity modulation strategies for soft tissue examination, Pages: 1998-2003, ISSN: 2153-0858

Advanced tactile tools in minimally invasive surgery have become a pressing need in order to reduce time and improve accuracy in localizing potential tissue abnormalities. In this regard, one of the main challenges is to be able to estimate tissue parameters in real time. In palpation, tactile information felt at a given location is identified by the viscoelastic dynamics of the neighboring tissue. Due to this reason the tissue examination behavior and the distribution of viscoelastic parameters in tissue should be considered in conjunction. This paper investigates the salient features of palpation behavior on soft tissue determining the effectiveness of localizing hard nodules. Experimental studies involving human participants, and validation tests using finite element simulations and a tele-manipulator, were carried out. Two distinctive tissue examination strategies in force-velocity modulation for the given properties of target tissue were found. Experimental results suggest that force-velocity modulations during continuous path measurements are playing an important role in the process of mechanical soft tissue examination. These behavioral insights, validated by detailed numerical models and robotic experimentations shed light on future designs of optimal robotic palpation. © 2013 IEEE.

CONFERENCE PAPER

Taylor JG, Cutsuridis V, Hartley M, Althoefer K, Nanayakkara Tet al., 2013, Observational Learning: Basis, Experimental Results and Models, and Implications for Robotics, COGNITIVE COMPUTATION, Vol: 5, Pages: 340-354, ISSN: 1866-9956

JOURNAL ARTICLE

Konstantinova J, Li M, Aminzadeh V, Althoefer K, Nanayakkara T, Dasgupta Pet al., 2013, Evaluating Manual Palpation Trajectory Patterns in Tele-Manipulation for Soft Tissue Examination, IEEE International Conference on Systems, Man, and Cybernetics (SMC), Publisher: IEEE, Pages: 4190-4195, ISSN: 1062-922X

CONFERENCE PAPER

Jiang A, Aste T, Dasgupta P, Althoefer K, Nanayakkara Tet al., 2013, Granular Jamming Transitions for a Robotic Mechanism, 7th International Conference on Micromechanics of Granular Media (Powders and Grains), Publisher: AMER INST PHYSICS, Pages: 385-388, ISSN: 0094-243X

CONFERENCE PAPER

, 2012, Locomotion with continuum limbs, Pages: 293-298, ISSN: 2153-0858

This paper presents the kinematics, dynamics, and experimental results for a novel quadruped robot using continuum limbs. We propose soft continuum limbs as a new paradigm for robotic locomotion in unstructured environments due to their potential to generate a wide array of locomotion behaviors ranging from walking, trotting, crawling, and propelling to whole arm grasping as a means of negotiating difficult obstacles. A straightforward method to derive the kinematics and dynamics for the proposed quadruped has been demonstrated through numerical simulations. Initial experiments on a prototype continuum quadruped demonstrate the ability to stand up from a flat-belly stance, absorb external disturbances such as maintaining stability after dropping from a height and after being perturbed by a collision, and crawling on flat and cluttered environments. Experiment results provide evidence that locomotion with soft continuum limbs are feasible and usable in unstructured environments for variety of applications. © 2012 IEEE.

CONFERENCE PAPER

, 2012, Design of a variable stiffness flexible manipulator with composite granular jamming and membrane coupling, Pages: 2922-2927, ISSN: 2153-0858

Robotic manipulators for minimally invasive surgeries have traditionally been rigid, with a steerable end effector. While the rigidity of manipulators improve precision and controllability, it limits reachability and dexterity in constrained environments. Soft manipulators with controllable stiffness on the other hand, can be deployed in single port or natural orifice surgical applications to reach a wide range of areas inside the body, while being able to passively adapt to uncertain external forces, adapt the stiffness distribution to suit the kinematic and dynamic requirements of the task, and provide flexibility for configuration control. Here, we present the design of a snake-like laboratory made soft robot manipulator of 20 mm in average diameter, which can actuate, soften, or stiffen joints independently along the length of the manipulator by combining granular jamming with McKibben actuators. It presents a comprehensive study on the relative contributions of the granule size, material type, and membrane coupling on the range, profile, and variability of stiffness. © 2012 IEEE.

CONFERENCE PAPER

, 2012, A computationally fast algorithm for local contact shape and pose classification using a tactile array sensor, Pages: 1410-1415, ISSN: 1050-4729

This paper proposes a new computationally fast algorithm for classifying the primitive shape and pose of the local contact area in real-time using a tactile array sensor attached on a robotic fingertip. The proposed approach abstracts the lower structural property of the tactile image by analyzing the covariance between pressure values and their locations on the sensor and identifies three orthogonal principal axes of the pressure distribution. Classifying contact shapes based on the principal axes allows the results to be invariant to the rotation of the contact shape. A naïve Bayes classifier is implemented to classify the shape and pose of the local contact shapes. Using an off-shelf low resolution tactile array sensor which comprises of 5x9 pressure elements, an overall accuracy of 97.5% has been achieved in classifying six primitive contact shapes. The proposed method is very computational efficient (total classifying time for a local contact shape = 576μs (1736 Hz)). The test results demonstrate that the proposed method is practical to be implemented on robotic hands equipped with tactile array sensors for conducting manipulation tasks where real-time classification is essential. © 2012 IEEE.

CONFERENCE PAPER

Nanayakkara T, Byl K, Liu H, Song X, Villabona Tet al., 2012, Dominant Sources of Variability in Passive Walking, IEEE International Conference on Robotics and Automation (ICRA), Publisher: IEEE, Pages: 1003-1010, ISSN: 1050-4729

CONFERENCE PAPER

Jiang A, Ataollahi A, Althoefer K, Dasgupta P, Nanayakkara Tet al., 2012, A VARIABLE STIFFNESS JOINT BY GRANULAR JAMMING, ASME International Design Engineering Technical Conferences/Computers Information in Engineering Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 267-+

CONFERENCE PAPER

Dias MB, Mills-Tettey GA, Nanayakkara T, 2005, Robotics, education, and sustainable development, IEEE International Conference on Robotics and Automation (ICRA), Publisher: IEEE, Pages: 4248-4253, ISSN: 1050-4729

CONFERENCE PAPER

Ariff G, Donchin O, Nanayakkara T, Shadmehr Ret al., 2002, A real-time state predictor in motor control: study of saccadic eye movements during unseen reaching movements., J Neurosci, Vol: 22, Pages: 7721-7729

Theoretical motor control predicts that because of delays in sensorimotor pathways, a neural system should exist in the brain that uses efferent copy of commands to the arm, sensory feedback, and an internal model of the dynamics of the arm to predict the future state of the hand (i.e., a forward model). We tested this theory under the hypothesis that saccadic eye movements, tracking an unseen reaching movement, would reflect the output of this state predictor. We found that in unperturbed reaching movements, saccade occurrence at any time t consistently provided an unbiased estimate of hand position at t + 196 msec. To investigate the behavior of this predictor during feedback error control, we applied 50 msec random-force perturbations to the moving hand. Saccades showed a sharp inhibition at 100 msec after perturbation. At approximately 170 msec, there was a sharp increase in saccade probabilities. These postperturbation saccades were an unbiased estimator of hand position at saccade time t + 150 msec. The ability of the brain to guide saccades to the future position of the hand failed when a force field unexpectedly changed the dynamics of the hand immediately after perturbation. The behavior of the eyes suggested that during reaching movements, the brain computes an estimate of future hand position based on an internal model that relies on real-time proprioceptive feedback. When an error occurs in reaching movements, the estimate of future hand position is recomputed. The saccade inhibition period that follows the hand perturbation may indicate the length of time it takes for this computation to take place.

JOURNAL ARTICLE

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