Publications
159 results found
Hamid E, Herzig N, Guaman SA-A, et al., 2021, A state-dependent damping method to reduce collision force and its variability, IEEE Robotics and Automation Letters, Vol: 6, Pages: 3025-3032, ISSN: 2377-3766
This letter investigates the effect of biologically inspired angle-dependent damping profile in a robotic joint primarily on the magnitude and the variability of the peak collision force. Joints such as the knee that experience collision forces are known to have an angle-dependent damping profile. In this letter, we have quantified and compared three damping profiles. Our numerical and experimental results show that the proposed hyperbolic angle-dependent damping profile can minimize both the magnitude and the variability of the peak collision force (average magnitude and variability reduction of ≈26% and ≈47% compared to the peak constant damping profile). Very often, the variability of the force across the collision between the robot and the environment cause uncertainty about the state variables of the robotic joint. We show that by increasing the slope of the proposed hyperbolic angle-dependent damping profile we can also reduce the variability and the magnitude of post-collision peak displacement and peak velocity compared to those of constant damping profile. This was achieved while reducing the root mean square of power consumed by the robotic joint.
Tan X, Ahmed-Kristensen S, Cao J, et al., 2021, A soft pressure sensor skin to predict contact pressure limit under hand orthosis, IEEE Transactions on Neural Systems and Rehabilitation Engineering, Vol: 29, Pages: 536-545, ISSN: 1534-4320
Customized static orthoses in rehabilitation clinics often cause side effects, such as discomfort and skin damage due to excessive local contact pressure. Currently, clinicians adjust orthoses to reduce high contact pressure based on subjective feedback from patients. However, the adjustment is inefficient and prone to variability due to the unknown contact pressure distribution as well as differences in discomfort due to pressure across patients. This paper proposed a new method to predict a threshold of contact pressure (pressure limit) associated with moderate discomfort at each critical spot under hand orthoses. A new pressure sensor skin with 13 sensing units was configured from FEA results of pressure distribution simulated with hand geometry data of six healthy participants. It was used to measure contact pressure under two types of customized orthoses for 40 patients with bone fractures. Their subjective perception of discomfort was also measured using a 6 scores discomfort scale. Based on these data, five critical spots were identified that correspond to high discomfort scores (>1) or high pressure magnitudes (>0.024 MPa). An artificial neural network was trained to predict contact pressure at each critical spot with orthosis type, gender, height, weight, discomfort scores and pressure measurements as input variables. The neural networks show satisfactory prediction accuracy with R 2 values over 0.81 of regression between network outputs and measurements. This new method predicts a set of pressure limits at critical locations under the orthosis that the clinicians can use to make orthosis adjustment decisions.
Sadati H, Naghib E, Shiva A, et al., 2021, TMTDyn: A Matlab package for modeling and control of hybrid rigid–continuum robots based on discretized lumped system and reduced-order models, International Journal of Robotics Research, Vol: 40, Pages: 296-347, ISSN: 0278-3649
A reliable, accurate, and yet simple dynamic model is important to analyzing, designing, and controlling hybrid rigid–continuum robots. Such models should be fast, as simple as possible, and user-friendly to be widely accepted by the ever-growing robotics research community. In this study, we introduce two new modeling methods for continuum manipulators: a general reduced-order model (ROM) and a discretized model with absolute states and Euler–Bernoulli beam segments (EBA). In addition, a new formulation is presented for a recently introduced discretized model based on Euler–Bernoulli beam segments and relative states (EBR). We implement these models in a Matlab software package, named TMTDyn, to develop a modeling tool for hybrid rigid–continuum systems. The package features a new high-level language (HLL) text-based interface, a CAD-file import module, automatic formation of the system equation of motion (EOM) for different modeling and control tasks, implementing Matlab C-mex functionality for improved performance, and modules for static and linear modal analysis of a hybrid system. The underlying theory and software package are validated for modeling experimental results for (i) dynamics of a continuum appendage, and (ii) general deformation of a fabric sleeve worn by a rigid link pendulum. A comparison shows higher simulation accuracy (8–14% normalized error) and numerical robustness of the ROM model for a system with a small number of states, and computational efficiency of the EBA model with near real-time performances that makes it suitable for large systems. The challenges and necessary modules to further automate the design and analysis of hybrid systems with a large number of states are briefly discussed.
Lalitharatne SWH, Tan Y, Leong F, et al., 2020, Facial Expression Rendering in Medical Training Simulators: Current Status and Future Directions, IEEE Access, Vol: 8, Pages: 215874-215891, ISSN: 2169-3536
Recent technological advances in robotic sensing and actuation methods have prompteddevelopment of a range of new medical training simulators with multiple feedback modalities. Learning tointerpret facial expressions of a patient during medical examinations or procedures has been one of the keyfocus areas in medical training. This article reviews facial expression rendering systems in medical trainingsimulators that have been reported to date. Facial expression rendering approaches in other domains are alsosummarized to incorporate the knowledge from those works into developing systems for medical trainingsimulators. Classifications and comparisons of medical training simulators with facial expression renderingare presented, and important design features, merits and limitations are outlined. Medical educators,students and developers are identified as the three key stakeholders involved with these systems and theirconsiderations and needs are presented. Physical-virtual (hybrid) approaches provide multimodal feedback,present accurate facial expression rendering, and can simulate patients of different age, gender and ethnicitygroup; makes it more versatile than virtual and physical systems. The overall findings of this review andproposed future directions are beneficial to researchers interested in initiating or developing such facialexpression rendering systems in medical training simulators.
Wegiriya H, Herzig N, Guaman SAA, et al., 2020, A stiffness controllable multimodal whisker sensor follicle for texture comparison, IEEE Sensors Journal, Vol: 20, Pages: 2320-2328, ISSN: 1530-437X
Mammals like rats, who live in dark burrows, heav-ily depend on tactile perception obtained through the vibrissalsystem to move through gaps and to discriminate textures. Theorganization of a mammalian whisker follicle contains multiplesensory receptors and glands strategically organized to capturetactile sensory stimuli of different frequencies. In this paper, weused a controllable stiffness soft robotic follicle to test the hy-pothesis that the multimodal sensory receptors together with thecontrollable stiffness tissues in the whisker follicle form a physicalstructure to maximize tactile information. In our design, the ringsinus and ringwulst of a biological follicle are represented by alinear actuator connected to a stiffness controllable mechanismin-between two different frequency-dependent data capturingmodules. In this paper, we show for the first time the effectof the interplay between the stiffness and the speed of whiskingon maximizing a difference metric for texture classification.
Herzig N, He L, Maiolino P, et al., 2020, Conditioned haptic perception for 3D localization of nodules in soft tissue palpation with a variable stiffness probe, PLoS One, Vol: 15, ISSN: 1932-6203
This paper provides a solution for fast haptic information gain during soft tissue palpation using a Variable Lever Mechanism (VLM) probe. More specifically, we investigate the impact of stiffness variation of the probe to condition likelihood functions of the kinesthetic force and tactile sensors measurements during a palpation task for two sweeping directions. Using knowledge obtained from past probing trials or Finite Element (FE) simulations, we implemented this likelihood conditioning in an autonomous palpation control strategy. Based on a recursive Bayesian inferencing framework, this new control strategy adapts the sweeping direction and the stiffness of the probe to detect abnormal stiff inclusions in soft tissues. This original control strategy for compliant palpation probes shows a sub-millimeter accuracy for the 3D localization of the nodules in a soft tissue phantom as well as a 100% reliability detecting the existence of nodules in a soft phantom.
Lu Q, Liang H, Nanayakkara DPT, et al., 2020, Precise in-hand manipulation of soft objects using soft fingertips with tactile sensing and active deformation, IEEE International Conference on Soft Robotics, Publisher: IEEE, Pages: 52-57
While soft fingertips have shown significant development for grasping tasks, its ability to facilitate the manipulation of objects within the hand is still limited. Thanks to elasticity, soft fingertips enhance the ability to grasp soft objects. However, the in-hand manipulation of these objects has proved to be challenging, with both soft fingertips and traditional designs, as the control of coordinated fine fingertip motions and uncertainties for soft materials are intricate. This paper presents a novel technique for in-hand manipulating soft objects with precision. The approach is based on enhancing the dexterity of robot hands via soft fingertips with tactile sensing and active shape changing; such that pressurized air cavities act as soft tactile sensors to provide closed loop control of fingertip position and avoid object’s damage, and pneumatic-tuned positive-pressure deformations act as a localized soft gripper to perform additional translations and rotations. We model the deformation of the soft fingertips to predict the in-hand manipulation of soft objects and experimentally demonstrate the resulting in-hand manipulationcapabilities of a gripper of limited dexterity with an algorithm based on the proposed dual abilities. Results show that the introduced approach can ease and enhance the prehensile in-hand translation and rotation of soft objects for precision tasks across the hand workspace, without damage.
Sadati SMH, Maiolino P, Iida F, et al., 2020, Editorial: current advances in soft robotics: best papers from RoboSoft 2018, Frontiers in Robotics and AI, Vol: 7, Pages: 1-2, ISSN: 2296-9144
He L, Lu Q, Abad S-A, et al., 2020, Soft fingertips with tactile sensing and active deformation for robust grasping of delicate objects, IEEE Robotics and Automation Letters, Vol: 5, Pages: 2714-2721, ISSN: 2377-3766
Soft fingertips have shown significant adaptability for grasping a wide range of object shapes, thanks to elasticity. This ability can be enhanced to grasp soft, delicate objects by adding touch sensing. However, in these cases, the complete restraint and robustness of the grasps have proved to be challenging, as the exertion of additional forces on the fragile object can result in damage. This letter presents a novel soft fingertip design for delicate objects based on the concept of embedded air cavities, which allow the dual ability of tactile sensing and active shape-changing. The pressurized air cavities act as soft tactile sensors to control gripper position from internal pressure variation; and active fingertip deformation is achieved by applying positive pressure to these cavities, which then enable a delicate object to be kept securely in position, despite externally applied forces, by form closure. We demonstrate this improved grasping capability by comparing the displacement of grasped delicate objects exposed to high-speed motions. Results show that passive soft fingertips fail to restrain fragile objects at accelerations as low as 0.1 m/s 2 , in contrast, with the proposed fingertips delicate objects are completely secure even at accelerations of more than 5 m/s 2 .
Xinyang T, He L, Cao J, et al., 2020, A soft pressure sensor skin for hand and wrist orthoses, IEEE Robotics and Automation Letters, Vol: 5, Pages: 2192-2199, ISSN: 2377-3766
Side effects caused by excessive contact pressure such as discomfort and pressure sores are commonly complained by patients wearing orthoses. These problems leading to low patient compliance decrease the effectiveness of the device. To mitigate side effects, this study describes the design and fabrication of a soft sensor skin with strategically placed 12 sensor units for static contact pressure measurement beneath a hand and wrist orthosis. A Finite Element Model was built to simulate the pressure on the hand of a subject and sensor specifications were obtained from the result to guide the design. By testing the fabricated soft sensor skin on the subject, contact pressure between 0.012 MPa and 0.046 MPa was detected, revealing the maximum pressure at the thumb metacarpophalangeal joint which was the same location of the highest pressure of simulation. In this letter, a new fabrication method combining etching and multi-material additive manufacture was introduced to produce multiple sensor units as a whole. Furthermore, a novel fish-scale structure as the connection among sensors was introduced to stabilize sensor units and reinforce the soft skin. Experimental analysis reported that the sensor signal is repeatable, and the fish-scale structure facilitates baseline resuming of sensor signal during relaxation.
Sadati H, Shiva A, Herzig N, et al., 2020, Stiffness imaging with a continuum appendage: Real-time shape and tip force estimation from base load readings, IEEE Robotics and Automation Letters, Vol: 5, Pages: 2824-2831, ISSN: 2377-3766
In this letter, we propose benefiting from load readings at the base of a continuum appendage for real-time forward integration of Cosserat rod model with application in configuration and tip load estimation. The application of this method is successfully tested for stiffness imaging of a soft tissue, using a 3-DOF hydraulically actuated braided continuum appendage. Multiple probing runs with different actuation pressures are used for mapping the tissue surface shape and directional linear stiffness, as well as detecting non-homogeneous regions, e.g. a hard nodule embedded in a soft silicon tissue phantom. Readings from a 6-axis force sensor at the tip is used for comparison and verification. As a result, the tip force is estimated with 0.016–0.037 N (7–20%) mean error in the probing and 0.02–0.1 N (6–12%) in the indentation direction, 0.17 mm (14%) mean error is achieved in estimating the surface profile, and 3.4–15 [N/m] (10–16%) mean error is observed in evaluating tissue directional stiffness, depending on the appendage actuation. We observed that if the appendage bends against the slider motion (toward the probing direction), it provides better horizontal stiffness estimation and better estimation in the perpendicular direction is achieved when it bends toward the slider motion (against the probing direction). In comparison with a rigid probe, $\approx \!\!10$ times smaller stiffness and $\approx \!\!7$ times larger mean standard deviation values were observed, suggesting the importance of a probe stiffness in estimation the tissue stiffness.
Scimeca L, Iida F, Maiolino P, et al., 2020, Human-Robot Medical Interaction, 15th Annual ACM/IEEE International Conference on Human-Robot Interaction (HRI), Publisher: ASSOC COMPUTING MACHINERY, Pages: 660-661, ISSN: 2167-2121
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Hughes J, Maiolino P, Nanayakkara T, et al., 2020, Sensorized Phantom For Characterizing Large Area Deformation of Soft Bodies for Medical Applications, 3rd IEEE International Conference on Soft Robotics (RoboSoft), Publisher: IEEE, Pages: 278-284
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- Citations: 5
Abad S-A, Herzig N, Sadati SMH, et al., 2019, Significance of the Compliance of the Joints on the Dynamic Slip Resistance of a Bioinspired Hoof, IEEE Transactions on Robotics, Vol: 35, Pages: 1450-1463, ISSN: 1552-3098
Robust mechanisms for slip resistance are an open challenge in legged locomotion. Animals such as goats show impressive ability to resist slippage on cliffs. It is not fully known what attributes in their body determine this ability. Studying the slip resistance dynamics of the goat may offer insight towards the biologically-inspired design of robotic hooves. This paper tests how the embodiment of the hoof contributes to solving the problem of slip resistance. We ran numerical simulations and experiments using a passive robotic goat hoof for different compliance levels of its 3 joints. We established that compliant yaw and pitch and stiff roll can increase the energy required to slide the hoof by ≈ 20% compared to the baseline (stiff hoof). Compliant roll and pitch allow the robotic hoof to adapt to the irregularities of the terrain. This produces an Anti-Lock Braking System-like behavior of the robotic hoof for slip resistance. Therefore, the pastern and coffin joints have a substantial effect on the slip resistance of the robotic hoof while the fetlock joint has the lowest contribution. These shed insights into how robotic hooves can be used to autonomously improve slip resistance.
Nanayakkara V, Sornkaran N, Wegiriya H, et al., 2019, A method to estimate the oblique arch folding axis for thumb assistive devices, 20th Towards Autonomous Robotic Systems Conference, Publisher: Springer Verlag, Pages: 28-40, ISSN: 0302-9743
People who use the thumb in repetitive manipulation tasks are likelyto develop thumb related impairments from excessive loading at the base jointsof the thumb. Biologically informed wearable robotic assistive mechanisms canprovide viable solutions to prevent occurring such injuries. This paper tests thehypothesis that an external assistive force at the metacarpophalangeal joint willbe most effective when applied perpendicular to the palm folding axis in termsof maximizing the contribution at the thumb-tip as well as minimizing the pro-jections on the vulnerable base joints of the thumb. Experiments conducted usinghuman subjects validated the predictions made by a simplified kinematic modelof the thumb that includes a foldable palm, showing that: 1) the palm folding an-gle varies from 71.5◦to 75.3◦(from the radial axis in the coronal plane) for thefour thumb-finger pairs and 2) the most effective assistive force direction (fromthe ulnar axis in the coronal plane) at the MCP joint is in the range 0◦<ψ<30◦for the four thumb-finger pairs. These findings provide design guidelines for handassistive mechanisms to maximize the efficacy of thumb external assistance.
Akhond S, Herzig N, Wegiriya H, et al., 2019, A method to guide local physical adaptations in a robot based on phase portraits, IEEE Access, Vol: 7, Pages: 1-13, ISSN: 2169-3536
In this paper, we propose a method that shows how phase portraits rendered by a controller can inform the development of a physical adaptation at a single degree of freedom (DoF) for a given control task. This approach has the advantage of having physical adaptations sharing the responsibility of control to accomplish a task. We use an inverted pendulum which is reminiscent of the trunk of a biped walker to conduct numerical simulations and hardware experiments to show how our method can innovate a physical adaptation at the pivot joint to reduce the control effort. Our method discovered that a torsional spring at the pivot joint would lead to a lower input effort by the regulator type feedback controller. The method can tune the spring to minimize the total cost of control up to about 32.81%. This physical adaptation framework allows multiple degrees of freedom robotic system to suggest local physical adaptations to accomplish a given control objective.
Gow J, Dijxhoorn E, Kerr R, et al., 2019, Routledge Handbook of War, Law and Technology, Publisher: Routledge, ISBN: 9781351619974
HANDBOOK. OF. WAR,. LAW. AND. TECHNOLOGY. This volume provides an authoritative, cutting-edge resource on the characteristics of both technological and social change in warfare in the twentyfirst century, and the challenges such ...
Shiva A, Sadati SH, Noh Y, et al., 2019, Elasticity vs hyperelasticity considerations in quasi-static modelling of a soft finger-like robotic appendage for real-time position and force estimation, Soft Robotics, Vol: 6, ISSN: 2169-5172
Various methods based on hyperelastic assumptions have been developed to address the mathematical complexities of modeling motion and deformation of continuum manipulators. In this study, we propose a quasistatic approach for 3D modeling and real-time simulation of a pneumatically actuated soft continuum robotic appendage to estimate the contact force and overall pose. Our model can incorporate external load at any arbitrary point on the body and deliver positional and force propagation information along the entire backbone. In line with the proposed model, the effectiveness of elasticity versus hyperelasticity assumptions (neo-Hookean and Gent) is investigated and compared. Experiments are carried out with and without external load, and simulations are validated across a range of Young's moduli. Results show best conformity with Hooke's model for limited strains with about 6% average normalized error of position; and a mean absolute error of less than 0.08 N for force applied at the tip and on the body, demonstrating high accuracy in estimating the position and the contact force.
Nanayakkara T, 2019, AUTONOMY OF HUMANS AND ROBOTS, ROUTLEDGE HANDBOOK OF WAR, LAW AND TECHNOLOGY, Editors: Gow, Dijxhoorn, Kerr, Verdirame, Publisher: ROUTLEDGE, Pages: 131-140, ISBN: 978-1-138-08455-1
Sadati SMH, Shiva A, Renson L, et al., 2019, Reduced Order vs. Discretized Lumped System Models with Absolute and Relative States for Continuum Manipulators, 15th Conference on Robotics - Science and Systems, Publisher: MIT PRESS
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- Citations: 4
Cotugno G, Konstantinova J, Althoefer K, et al., 2018, Modelling the structure of object-independent human affordances of approaching to grasp for robotic hands, PLoS ONE, Vol: 13, ISSN: 1932-6203
Grasp affordances in robotics represent different ways to grasp an object involving a variety of factors from vision to hand control. A model of grasp affordances that is able to scale across different objects, features and domains is needed to provide robots with advanced manipulation skills. The existing frameworks, however, can be difficult to extend towards a more general and domain independent approach. This work is the first step towards a modular implementation of grasp affordances that can be separated into two stages: approach to grasp and grasp execution. In this study, human experiments of approaching to grasp are analysed, and object-independent patterns of motion are defined and modelled analytically from the data. Human subjects performed a specific action (hammering) using objects of different geometry, size and weight. Motion capture data relating the hand-object approach distance was used for the analysis. The results showed that approach to grasp can be structured in four distinct phases that are best represented by non-linear models, independent from the objects being handled. This suggests that approaching to grasp patterns are following an intentionally planned control strategy, rather than implementing a reactive execution.
Wijesundera I, Halgamuge M, Nirmalathas A, et al., 2018, Predicting the Mean First Passage Time (MFPT) to reach any state for a passive dynamic walker with steady state variability, PLoS ONE, Vol: 13, ISSN: 1932-6203
Idealized passive dynamic walkers (PDW) exhibit limit cycle stability at steady state. Yet in reality, uncertainty in ground interaction forces result in variability in limit cycles even for a simple walker known as the Rimless Wheel (RW) on seemingly even slopes. This class of walkers is called metastable walkers in that they usually walk in a stable limit cycle, though guaranteed to eventually fail. Thus, control action is only needed if a failure state (i.e. RW stopping down the ramp) is imminent. Therefore, efficiency of estimating the time to reach a failure state is key to develop a minimal intervention controller to inject just enough energy to overcome a failure state when required. Current methods use what is known as a Mean First Passage Time (MFPT) from current state (rotary speed of RW at the most recent leg collision) to an arbitrary state deemed to be a failure in the future. The frequently used Markov chain based MFPT prediction requires an absorbing state, which in this case is a collision where the RW comes to a stop without an escape. Here, we propose a novel method to estimate an MFPT from current state to an arbitrary state which is not necessarily an absorbing state. This provides freedom to a controller to adaptively take action when deemed necessary. We demonstrate the proposed MFPT predictions in a minimal intervention controller for a RW. Our results show that the proposed method is useful in controllers for walkers showing up to 44.1% increase of time-to-fail compared to a PID based closed-loop controller.
He L, Herzig N, Lusignan SD, et al., 2018, Granular jamming based controllable organ design for abdominal palpation, 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Publisher: IEEE
Medical manikins play an essential role in the training process of physicians. Currently, most available simulators for abdominal palpation training do not contain controllable organs for dynamic simulations. In this paper, we present a soft robotics controllable liver that can simulate various liver diseases and symptoms for effective and realistic palpation training. The tumors in the liver model are designed based on granular jamming with positive pressure, which converts the fluid-like impalpable particles to a solid-like tumor state by applying low positive pressure on the membrane. Through inflation, the tumor size, liver stiffness, and liver size can be controlled from normal liver state to various abnormalities including enlarged liver, cirrhotic liver, and multiple cancerous and malignant tumors. Mechanical tests have been conducted in the study to evaluate the liver design and the role of positive pressure granular jamming in tumor simulations.
Nanayakkara T, Sahin F, Jamshidi M, 2018, Intelligent Control Systems with an Introduction to System of Systems Engineering, Publisher: CRC Press, ISBN: 9781351834537
Azani, C., “An open systems approach to system of systems engineering” System of Systems Engineering— Innovations for the 21st Century, John Wiley Series on Systems Engineering (M. Jamshidi, Ed.). Wiley, New York, 2008. Sage, A. P. ...
Sadati SH, Sullivan L, Walker ID, et al., 2018, 3D-printable thermoactive helical interface with decentralized morphological stiffness control for continuum manipulators, IEEE International Conference on Robotics and Automation, Publisher: Institute of Electrical and Electronics Engineers, Pages: 2283-2290, ISSN: 2377-3766
We present a three-dimensional (3-D)-printable thermoactive scale jamming interface as a new way to control a continuum manipulator dexterity by taking inspiration from the helical arrangement of fish scales. A highly articulated helical interface is 3-D-printed with thermoactive functionally graded joints using a conventional 3-D printing device that utilizes UV curable acrylic plastic and hydroxylated wax as the primary and supporting material. The joint compliance is controlled by regulating wax temperature in phase transition. Empirical feed-forward control relations are identified through comprehensive study of the wax melting profile and actuation scenarios for different shaft designs to achieve desirable repeatability and response time. A decentralized control approach is employed by relating the mathematical terms of the Cosserat beam method to their morphological counterparts in which the manipulator local anisotropic stiffness is controlled based on the local stress and strain information. As a result, a minimalistic central controller is designed in which the joints' thermomechanical states are observed using a morphological observer, an external fully monitored replica of the observed system with the same inputs. Preliminary results for passive shape adaptation, geometrical disturbance rejection, and task space anisotropic stiffness control are reported by integrating the interface on a continuum manipulator.
Ranasinghe A, Dasgupta P, Nagar A, et al., 2018, Human behavioral metrics of a predictive model emerging during robot assisted following without visual feedback, IEEE Robotics and Automation Letters, Vol: 3, Pages: 2624-2631, ISSN: 2377-3766
Robot-assisted guiding is gaining increased interest due to many applications involving moving in the noisy and low visibility environments. In such cases, haptic feedback is the most effective medium to communicate. In this letter, we focus on perturbation-based haptic feedback due to applications like guide dogs for visually impaired people and potential robotic counterparts providing haptic feedback via reins to assist indoor fire fighting. Since proprioceptive sensors like spindles and tendons are part of the muscles involved in the perturbation, haptic perception becomes a coupled phenomenon with spontaneous reflex muscle activity. The nature of this interplay and how the model-based sensory-motor integration evolves during haptic-based guiding is not well understood yet. We asked human followers to hold the handle of a hard rein attached to a one-DoF robotic arm that gave perturbations to the hand to correct an angle error of the follower. We found that followers start with a second-order reactive autoregressive following model and changes it to a predictive model with training. The reduction in cocontraction of muscles and leftward/rightward asymmetry of a set of followers behavioral metrics show that the model-based prediction accounts for the internal coupling between proprioception and muscle activity during perturbation responses.
Konstantinova J, Cotugno G, Dasgupta P, et al., 2018, Correction: Palpation force modulation strategies to identify hard regions in soft tissue organs, PLoS One, Vol: 13, Pages: 1-1, ISSN: 1932-6203
Herzig N, Maiolino P, Iida F, et al., 2018, A Variable Stiffness Robotic Probe for Soft Tissue Palpation, IEEE Robotics and Automation Letters, Vol: 3, Pages: 1168-1175, ISSN: 2377-3766
During abdominal palpation diagnosis, a medical practitioner would change the stiffness of their fingers in order to improve the detection of hard nodules or abnormalities in soft tissue to maximize the haptic information gain via tendons. Our recent experiments using a controllable stiffness robotic probe representing a human finger also confirmed that such stiffness control in the finger can enhance the accuracy of detecting hard nodules in soft tissue. However, the limited range of stiffness achieved by the antagonistic springs variable stiffness joint subject to size constraints made it unsuitable for a wide range of physical examination scenarios spanning from breast to abdominal examination. In this letter, we present a new robotic probe based on a variable lever mechanism able to achieve stiffness ranging from 0.64 to 1.06 N ⋅m/rad that extends the maximum stiffness by around 16 times and the stiffness range by 33 times. This letter presents the mechanical model of the novel probe, the finite element simulation as well as experimental characterization of the stiffness response for lever actuation.
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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Sadati SMH, Naghibi SE, Althoefer K, et al., 2018, Toward a Low Hysteresis Helical Scale Jamming Interface Inspired by Teleost Fish Scale Morphology and Arrangement, 1st IEEE-RAS International Conference on Soft Robotics (RoboSoft), Publisher: IEEE, Pages: 455-460
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- Citations: 2
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