Publications
160 results found
Weheliye A, Sornkarn N, Dasgupta P, et al., 2018, Haptic Information Gain in Remote Soft Tissue Examination Using a Controllable Stiffness Robotic Probe, 9th IEEE International Conference on Information and Automation for Sustainability (ICIAfS), Publisher: IEEE, ISSN: 2151-1802
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- Citations: 1
Ranasinghe A, Weheliye A, Dasgupta P, et al., 2018, Representation of Distributed Haptic Feedback Given via Vibro-tactile Actuator Arrays, SOFT AND STIFFNESS-CONTROLLABLE ROBOTICS SOLUTIONS FOR MINIMALLY INVASIVE SURGERY: THE STIFF-FLOP APPROACH, Editors: Konstantinova, Wurdemann, Shafti, Shiva, Althoefer, Publisher: RIVER PUBLISHERS, Pages: 263-287, ISBN: 978-87-93519-72-5
Mosquera DG, Sadati SMH, Althoefer K, et al., 2018, Smart Hydrogel for Stiffness Controllable Continuum Manipulators: A Conceptual Design, SOFT AND STIFFNESS-CONTROLLABLE ROBOTICS SOLUTIONS FOR MINIMALLY INVASIVE SURGERY: THE STIFF-FLOP APPROACH, Editors: Konstantinova, Wurdemann, Shafti, Shiva, Althoefer, Publisher: RIVER PUBLISHERS, Pages: 79-96, ISBN: 978-87-93519-72-5
Sadati SMH, Naghibi SE, Walker ID, et al., 2017, Control Space Reduction and Real-Time Accurate Modeling of Continuum Manipulators Using Ritz and Ritz–Galerkin Methods, IEEE Robotics and Automation Letters, Vol: 3, Pages: 328-335, ISSN: 2377-3766
To address the challenges with real-time accurate modeling of multisegment continuum manipulators in the presence of significant external and body loads, we introduce a novel series solution for variable-curvature Cosserat rod static and Lagrangian dynamic methods. By combining a modified Lagrange polynomial series solution, based on experimental observations, with Ritz and Ritz-Galerkin methods, the infinite modeling state space of a continuum manipulator is minimized to geometrical position of a handful of physical points (in our case two). As a result, a unified easy to implement vector formalism is proposed for the nonlinear impedance and configuration control. We showed that by considering the mechanical effects of highly elastic axial deformation, the model accuracy is increased up to 6%. The proposed model predicts experimental results with 6%-8% (4-6 mm) mean error for the Ritz-Galerkin method in static cases and 16%-20% (12-14 mm) mean error for the Ritz method in dynamic cases, in planar and general three-dimensional motions. Comparing to five different models in the literature, our approximate solution is shown to be more accurate with the smallest possible number of modeling states and suitable for real-time modeling, observation, and control applications.
Sadati SM, Naghibi SE, Shiva A, et al., 2017, Mechanics of continuum manipulators, a comparative study of five methods with experiments, TAROS 2017, Publisher: Springer, Pages: 686-702, ISSN: 0302-9743
Investigations on control and optimization of continuum manipulators have resulted in a number of kinematic and dynamic modeling approaches each having their own advantages and limitations in various applications. In this paper, a comparative study of five main methods in the literature for kinematic, static and dynamic modeling of continuum manipulators is presented in a unified mathematical framework. The five widely used methods of Lumped system dynamic model, Constant curvature, two-step modified constant curvature, variable curvature Cosserat rod and beam theory approach, and series solution identification are re-viewed here with derivation details in order to clarify their methodological differences. A comparison between computer simulations and experimental results using a STIFF-FLOP continuum manipulator is presented to study the advantages of each modeling method.
Afrisal H, Sadati SMH, Nanayakkara T, 2017, A bio-Inspired electro-active velcro mechanism using shape memory alloy for wearable and stiffness controllable layers, 8th IEEE International Conference on Information and Automation for Sustainability (ICIAfS) - Interoperable Sustainable Smart Systems for Next Generation, Publisher: IEEE, ISSN: 2151-1802
Smart attachment mechanisms are believed to contribute significantly in stiffness control of soft robots. This paper presents a working prototype of an active Velcro based stiffness controllable fastening mechanism inspired from micro active hooks found in some species of plants and animals. In contrast to conventional passive Velcro, this active Velcro mechanism can vary the stiffness level of its hooks to adapt to external forces and to maintain the structure of its supported layer. The active hooks are fabricated using Shape Memory Alloy (SMA) wires which can be actuated using Lenz-Joule heating technique via thermo-electric manipulation. In this paper, we show experimental results for the effects of active SMA Velcro temperature, density and number on the attachment resisting force profile in dynamic displacement. We aim to provide new insights into the novel design approach of using active hook systems to support future implementation of active velcro mechanisms for fabrication of wearable stiffness controllable thin layers.
Sadati SMH, Naghibi SE, Shiva A, et al., 2017, A geometry deformation model for braided continuum manipulators, Frontiers Robotics AI, Vol: 4
Continuum manipulators have gained significant attention in the robotic community due to their high dexterity, deformability, and reachability. Modeling of such manipulators has been shown to be very complex and challenging. Despite many research attempts, a general and comprehensive modeling method is yet to be established. In this paper, for the first time, we introduce the bending effect in the model of a braided extensile pneumatic actuator with both stiff and bendable threads. Then, the effect of the manipulator cross-section deformation on the constant curvature and variable curvature models is investigated using simple analytical results from a novel geometry deformation method and is compared to experimental results. We achieve 38% mean reference error simulation accuracy using our constant curvature model for a braided continuum manipulator in presence of body load and 10% using our variable curvature model in presence of extensive external loads. With proper model assumptions and taking to account the cross-section deformation, a 7-13% increase in the simulation mean error accuracy is achieved compared to a fixed cross-section model. The presented models can be used for the exact modeling and design optimization of compound continuum manipulators by providing an analytical tool for the sensitivity analysis of the manipulator performance. Our main aim is the application in minimal invasive manipulation with limited workspaces and manipulators with regional tunable stiffness in their cross section.
Nanayakkara DPT, Konstantinova J, Cotugno G, et al., 2017, Palpation force modulation strategies to identify hard regions in soft tissue organs, PLOS One, Vol: 12, ISSN: 1932-6203
This paper presents experimental evidence for the existence of a set of unique force modulation strategies during manual soft tissue palpation to locate hard abnormalities such as tumors. We explore the active probing strategies of defined local areas and outline the role of force control. In addition, we investigate whether the applied force depends on the non-homogeneity of the soft tissue. Experimental results on manual palpation of soft silicone phantoms show that humans have a well defined force control pattern of probing that is used independently of the non-homogeneity of the soft tissue. We observed that the modulations of lateral forces are distributed around the mean frequency of 22.3 Hz. Furthermore, we found that the applied normal pressure during probing can be modeled using a second order reactive autoregressive model. These mathematical abstractions were implemented and validated for the autonomous palpation for different stiffness parameters using a robotic probe with a rigid spherical indentation tip. The results show that the autonomous robotic palpation strategy abstracted from human demonstrations is capable of not only detecting the embedded nodules, but also enhancing the stiffness perception compared to static indentation of the probe.
Wegiriya H, Sornkarn N, Bedford H, et al., 2017, A biologically inspired multimodal whisker follicle, 2016 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2016 - Conference Proceedings, Pages: 3847-3852
Mammalian whisker follicle contains multiple sensory receptors strategically organized to capture tactile sensory stimuli of different frequencies via the vibrissal system. There have been a number of attempts to develop robotic whiskers to perform texture classification tasks in the recent past. Inspired by the features of biological whisker follicle, in this paper we design and use a novel soft whisker follicle comprising of two different frequency-dependent data capturing modules to derive deeper insights into the biological basis of tactile perception in the mammalian whisker follicle. In our design, the innervations at the Outer Conical Body (OCB) of a biological follicle are realized by a piezoelectric transducer for capturing high frequency components; whereas the innervations around the hair Papilla are represented by a hall sensor to capture low frequency components during the interaction with the environment. In this paper, we show how low dimensional information such as the principle components of co-variation of these two sensory modalities vary for different speeds and indentations of brushing the whisker against a surface. These new insights into the biological basis of tactile perception using whiskers provides new design guidelines to develop efficient robotic whiskers.
Nanayakkara VK, Cotugno G, Vitzilaios N, et al., 2017, The Role of Morphology of the Thumb in Anthropomorphic Grasping: A Review, Frontiers in Mechanical Engineering, Vol: 3
The unique musculoskeletal structure of the human hand brings in wider dexterous capabilities to grasp and manipulate a repertoire of objects than the non-human primates. It has been widely accepted that the orientation and the position of the thumb plays an important role in this characteristic behavior. There have been numerous attempts to develop anthropomorphic robotic hands with varying levels of success. Nevertheless, manipulation ability in those hands is to be ameliorated even though they can grasp objects successfully. An appropriate model of the thumb is important to manipulate the objects against the fingers and to maintain the stability. Modeling these complex interactions about the mechanical axes of the joints and how to incorporate these joints in robotic thumbs is a challenging task. This article presents a review of the biomechanics of the human thumb and the robotic thumb designs to identify opportunities for future anthropomorphic robotic hands.
Rijanto E, Sugiharto A, Utomo S, et al., 2017, Trends in Robot Assisted Endovascular Catheterization Technology: A Review, International Conference on Robotics, Biomimetics, and Intelligent Computational Systems (Robionetics), Publisher: IEEE, Pages: 34-41
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- Citations: 2
Ranasinghe A, Althoefer K, Dasgupta P, et al., 2017, Wearable Haptic Based Pattern Feedback Sleeve System, 6th International Conference on Soft Computing for Problem Solving (SocProS), Publisher: SPRINGER-VERLAG BERLIN, Pages: 302-312, ISSN: 2194-5357
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- Citations: 1
Abad S-A, Sornkarn N, Nanayakkara T, 2016, The role of morphological computation of the goat hoof in slip reduction, IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Publisher: IEEE, Pages: 5599-5605, ISSN: 2153-0866
The remarkable ability of goats to maintain stability during climbing cliffs or trees provides a valuable opportunity to understand some of the secrets of stable legged locomotion on unstructured terrains. This paper, for the first time, presents analytical and experimental explanations as to how the morphological computation at the goat hoof makes a significant contribution to slip reduction on both smooth and rough surfaces. We conducted experiments using a laboratory made hoof and compared its dynamic behavior against a rounded foot. We recorded forces and position of the hoof to analyze the effect of its shape and the individual contributions from 3-joints in the hoof on the work required to slip. Results state that the work required to move the hoof is more than 3 times that required to move a rounded foot. Additionally, the variables in the transient state are affected not only by the number and type of joints but also by the interaction with the environment. These findings promote the development of new types of feet for robots for all terrain conditions with greater stability and less control complexity.
Wijesundera I, Halgamuge MN, Nirmalathas A, et al., 2016, MFPT calculation for random walks in inhomogeneous networks, PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, Vol: 462, Pages: 986-1002, ISSN: 0378-4371
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- Citations: 4
Sornkarn N, Nanayakkara T, 2016, Can a Soft Robotic Probe Use Stiffness Control Like a Human Finger to Improve Efficacy of Haptic Perception?, IEEE TRANSACTIONS ON HAPTICS, Vol: 10, Pages: 183-195, ISSN: 1939-1412
When humans are asked to palpate a soft tissue to locate a hard nodule, they regulate the stiffness, speed, and force of the finger during examination. If we understand the relationship between these behavioral variables and haptic information gain (transfer entropy) during manual probing, we can improve the efficacy of soft robotic probes for soft tissue palpation, such as in tumor localization in minimally invasive surgery. Here, we recorded the muscle co-contraction activity of the finger using EMG sensors to address the question as to whether joint stiffness control during manual palpation plays an important role in the haptic information gain. To address this question, we used a soft robotic probe with a controllable stiffness joint and a force sensor mounted at the base to represent the function of the tendon in a biological finger. Then, we trained a Markov chain using muscle co-contraction patterns of human subjects, and used it to control the stiffness of the soft robotic probe in the same soft tissue palpation task. The soft robotic experiments showed that haptic information gain about the depth of the hard nodule can be maximized by varying the internal stiffness of the soft probe.
Konstantinova J, Cotugno G, Dasgupta P, et al., 2016, Autonomous robotic palpation of soft tissue using the modulation of applied force, IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics 2016, Publisher: IEEE, Pages: 323-328, ISSN: 2155-1774
Palpation or perception of tactile information from soft tissue organs during minimally invasive surgery is required to improve clinical outcomes. One of the methods of palpation includes examination using the modulation of applied force on the localized area. This paper presents a method of soft tissue autonomous palpation based on the mathematical model obtained from human tactile examination data using modulations of palpation force. Using a second order reactive auto-regressive model of applied force, a robotic probe with spherical indenter was controlled to examine silicone tissue phantoms containing artificial nodules. The results show that the autonomous palpation using the model abstracted from human demonstration can be used not only to detect embedded nodules, but also to enhance the stiffness perception compared to the static indentation of the probe.
Chathuranga DS, Wang Z, Noh Y, et al., 2016, Magnetic and Mechanical Modeling of a Soft Three-Axis Force Sensor, IEEE SENSORS JOURNAL, Vol: 16, Pages: 5298-5307, ISSN: 1530-437X
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- Citations: 25
Nanayakkara V, Ataka A, Venetsanos D, et al., 2016, Kinematic analysis of the human thumb with foldable palm, TAROS 2016, Publisher: Springer, Pages: 226-238, ISSN: 0302-9743
There have been numerous attempts to develop anthropomorphic robotic hands with varying levels of dexterous capabilities. However, these robotic hands often suffer from a lack of comprehensive understanding of the musculoskeletal behavior of the human thumb with integrated foldable palm. This paper proposes a novel kinematic model to analyze the importance of thumb-palm embodiment in grasping objects. The model is validated using human demonstrations for five precision grasp types across five human subjects. The model is used to find whether there are any co-activations among the thumb joint angles and muskuloskeletal parameters of the palm. In this paper we show that there are certain pairs of joints that show stronger linear relationships in the torque space than in joint angle space. These observations provide useful design guidelines to reduce control complexity in anthropomorphic robotic thumbs.
Sornkarn N, Nanayakkara T, 2016, The efficacy of interaction behavior and internal stiffness control for embodied information gain in haptic perception, IEEE International Conference on Robotics and Automation (ICRA) 2016, Publisher: IEEE, Pages: 2657-2662, ISSN: 1050-4729
Haptic perception in biological systems not only depends on the environmental conditions, but also on the behavioral state and the internal impedance of the embodiment because proprioceptive sensors are embedded in the muscle and tendons used for actuation. A simple example of such a phenomenon can be found when people are asked to palpate a soft tissue to identify a stiff-inclusion. People tend to perform a variety of palpation strategies depending on their previous knowledge and the desired information. Does this mean that the probing behavioral variables and internal muscle impedance parameters and their interaction with given environmental conditions play a role in the perception information gain during the estimation of soft tissue's properties? In this paper, we use a two-degree of freedom laboratory-made variable stiffness and indentation probe to investigate how the modulation of probing behavioral and internal stiffness variables can affect the accuracy of the depth estimation of stiff inclusions in artificial silicon phantom tissue using information gain metrics based on prior knowledge in form of memory primitives.
Sadati SMH, Shiva A, Ataka A, et al., 2016, A geometry deformation model for compound continuum manipulators with external loading, 2016 IEEE International Conference on Robotics and Automation, Pages: 4957-4962, ISSN: 1050-4729
© 2016 IEEE. The complexity of soft continuum manipulators with hybrid and tuneable structures poses a challenging task to achieve an inverse kinematics model which is both precise and computationally efficient for control and optimization purposes. In this paper, a new method based on the principle of virtual work and a geometry deformation approach is presented for the inverse kinematics model of the STIFF-FLOP arm which is a pneumatically actuated continuum manipulator. We propose a novel simplified and computationally efficient yet accurate analytical solution to analyse the static behaviour of a compound soft manipulator in the presence of external and body forces which is verified against experimental data, showing promising agreement with 10% mean error for planar movements. In the process, we present a new modelling approach for braided soft extensor actuators with no braid-surface relative slip constraint. For the first time, our model predicts a simple analytical solution for the cross section deformation which is essential to control soft manipulators with regional tunable stiffness structure.
Sornkarn N, Dasgupta P, Nanayakkara T, 2016, Morphological computation of haptic perception of a controllable stiffness probe, PLOS One, Vol: 11, ISSN: 1932-6203
When people are asked to palpate a novel soft object to discern its physical properties such as texture, elasticity, and even non-homogeneity, they not only regulate probing behaviors, but also the co-contraction level of antagonistic muscles to control the mechanical impedance of fingers. It is suspected that such behavior tries to enhance haptic perception by regulating the function of mechanoreceptors at different depths of the fingertips and proprioceptive sensors such as tendon and spindle sensors located in muscles. In this paper, we designed and fabricated a novel two-degree of freedom variable stiffness indentation probe to investigate whether the regulation of internal stiffness, indentation, and probe sweeping velocity (PSV) variables affect the accuracy of the depth estimation of stiff inclusions in an artificial silicon phantom using information gain metrics. Our experimental results provide new insights into not only the biological phenomena of haptic perception but also new opportunities to design and control soft robotic probes.
Nanayakkara T, Jiang A, Del Rocío Armas Fernández M, et al., 2016, Stable grip control on soft objects with time-varying stiffness, IEEE Transactions on Robotics, Vol: 32, Pages: 626-637, ISSN: 1552-3098
Humans can hold a live animal like a hamster without overly squeezing despite the fact that its soft body undergoes impedance and size variations due to breathing and wiggling. Although the exact nature of such biological motor controllers is not known, existing literature suggests that they maintain metastable interactions with dynamic objects based on prediction rather than reaction. Most robotic gripper controllers find such tasks very challenging mainly due to hard constraints imposed on the stability of closed-loop control and inadequate rates of convergence of adaptive controller parameters. This paper presents experimental and numerical simulation results of a control law based on a relaxed stability criterion of reducing the probability of failure to maintain a stable grip on a soft object that undergoes temporal variations in its internal impedance. The proposed controller uses only three parameters to interpret the probability of failure estimated using a history of grip forces to adjust the grip on the dynamic object. Here, we demonstrate that the proposed controller can maintain smooth and stable grip tightening and relaxing when the object undergoes random impedance variations, compared with a reactive controller that involves a similar number of controller parameters.
Wijesundera I, Halgamuge MN, Nanayakkara T, et al., 2016, Natural Disasters, When Will They Reach Me?, Publisher: Springer, ISBN: 9789811011139
A complex natural process that occurs on earth is referred to as a natural disaster when it results in catastrophic life, economic and structural losses. Ranging from cyclone activity, bushfire, and tsunami waves to thunderstorms, earthquake and ...
Cotugno G, Althoefer K, Nanayakkara T, 2016, The Role of the Thumb: Study of Finger Motion in Grasping and Reachability Space in Human and Robotic Hands, IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS, Vol: 47, Pages: 1061-1070, ISSN: 2168-2216
It is well acknowledged that the opposing thumb granted humans advanced manipulation capabilities. However, such a feature is not statistically quantified, and its representation is not formally addressed in robotics yet. This paper studies whether the displacement of the opposing thumb in humans is a determining factor for shaping the grip. Using statistical analysis of the variability of motion capture data from the GRASP database, we found that the displacement of the thumb plays a leading role on the shaping of the grip, independently from the specific object being grasped. Furthermore, we map and compare the reachability spaces of the human thumb and two state-of-the-art robotic thumbs: (1) the shadow and (2) the iCub hands. We conclude that the kinematics of robotic thumbs does not evenly span the reachability space of the human thumb, favoring precision grasping motions. Hence, our findings contribute to the discussion of the optimal modeling of robotic hands.
Chathuranga DS, Wang Z, Noh Y, et al., 2016, A Soft Three Axis Force Sensor Useful for Robot Grippers, IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Publisher: IEEE, Pages: 5556-5563
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- Citations: 7
Li M, Konstantinova J, Secco EL, et al., 2015, Using visual cues to enhance haptic feedback for palpation on virtual model of soft tissue, MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING, Vol: 53, Pages: 1177-1186, ISSN: 0140-0118
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- Citations: 22
Ranasinghe A, Dasgupta P, Althoefer K, et al., 2015, Identification of Haptic Based Guiding Using Hard Reins, PLOS ONE, Vol: 10, ISSN: 1932-6203
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- Citations: 6
Ranasinghe A, Sornkarn N, Dasgupta P, et al., 2015, Salient feature of haptic-ased guidance of people in low visibility environments using hard reins., IEEE Transactions on Cybernetics, Vol: 46, Pages: 568-579, ISSN: 2168-2267
This paper presents salient features of human-human interaction where one person with limited auditory and visual perception of the environment (a follower) is guided by an agent with full perceptual capabilities (a guider) via a hard rein along a given path. We investigate several salient features of the interaction between the guider and follower such as: 1) the order of an autoregressive (AR) control policy that maps states of the follower to actions of the guider; 2) how the guider may modulate the pulling force in response to the trust level of the follower; and 3) how learning may successively apportion the responsibility of control across different muscles of the guider. Based on experimental systems identification on human demonstrations from ten pairs of naive subjects, we show that guiders tend to adopt a third-order AR predictive control policy and followers tend to adopt second-order reactive control policy. Moreover, the extracted guider's control policy was implemented and validated by human-robot interaction experiments. By modeling the follower's dynamics with a time varying virtual damped inertial system, we found that it is the coefficient of virtual damping which is most sensitive to the trust level of the follower. We used these experimental insights to derive a novel controller that integrates an optimal order control policy with a push/pull force modulator in response to the trust level of the follower monitored using a time varying virtual damped inertial model.
Gonzalez-Fierro M, Hernandez-Garcia D, Nanayakkara T, et al., 2015, Behavior sequencing based on demonstrations: a case of a humanoid opening a door while walking, ADVANCED ROBOTICS, Vol: 29, Pages: 315-329, ISSN: 0169-1864
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- Citations: 5
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