This paper presents the development and evaluation of a miniature, three-axis, fiber-optic force ... more This paper presents the development and evaluation of a miniature, three-axis, fiber-optic force sensor. The sensor is manufactured using low-cost, high-resolution rapid prototyping techniques and is integrated with a catheter to enable the detection of force during MRI-guided cardiac ablation procedures. The working principle is based on reflective light-intensity modulation. A force sensitive structure (flexure) is employed to vary the distance and orientation of an integrated reflector when a force is applied at the catheter tip. In this way, the light is modulated accordingly and the force can be calculated. The sensor has a high sensitivity and an adequate linear response along all three orthogonal axes (Fx, Fy, and Fz) and a working range of around 0.5 N. Low-noise, high-gain electronics provide a force resolution of less than 1 gm force. Experiments demonstrate the ability of the sensor to acquire accurate force readings in a dynamic environment. MRI-compatibility experiments are performed in a clinical 1.5-T MR scanner.
IEEE transactions on bio-medical engineering (TBME), 2013
This paper presents a novel MR-compatible 3-DOF cardiac catheter steering mechanism. The catheter... more This paper presents a novel MR-compatible 3-DOF cardiac catheter steering mechanism. The catheter's steerable structure is tendon driven and consists of miniature deflectable, helical segments created by a precise rapid prototyping technique. The created catheter prototype has an outer diameter of 9 Fr (3 mm) and a steerable distal end that can be deflected in 3D space via four braided high-tensile Spectra® fiber tendons. Any longitudinal twist commonly observed in helical structures is compensated for by employing clockwise (CW) and counter clockwise (CCW) helical segments in an alternating fashion. A 280 μm flexible carbon fiber rod is used as a backbone in a central channel to improve the structure's steering and positioning repeatability. In addition to the backbone, a carbon fiber tube can be inserted into the structure to a varying amount capable of changing the structure's forcibility and, thus, providing a means to change the curvature and to modify the deflectable length of the catheter leading to an extension of reachable points in the catheter-tip workspace. A unique feature of this helical segment structure is that the stiffness can be further adjusted by appropriately tensioning tendons simultaneously. An experimental study has been conducted examining the catheter-tip trajectory in 3D space and its positioning repeatability using a 5-DOF magnetic coil tracking system. Furthermore, MRI experiments in a 1.5 Tesla scanner confirmed the MR-compatibility of the catheter prototype. The study shows that the proposed concept for catheter steering has great potential to be employed for robotically steered and MRguided cardiac catheterization.
IEEE Transactions on Biomedical Engineering (TBME), 2013
"This paper presents a novel palpation probe based on optical fiber technology. It is des... more "This paper presents a novel palpation probe based on optical fiber technology. It is designed to measure stiffness distribution of a soft tissue while sliding over the tissue surface in a near frictionless manner. A novelty of the probe is its ability to measure indentation depth for non-planar tissue profiles which are commonly experienced during surgery. Since tumors are often harder than the surrounding tissue, the proposed probe can intra-operatively aid the surgeon to rapidly identify the presence, location and size of the tumors through the generation of a tissue stiffness map. The probe can concurrently measure tissue reaction force, indentation depth and the orientation of the probe with respect to the tissue surface. Hence it can generate an elasticity model of the tissue with minimum measurement inaccuracies caused by surface profile variations. Further, the probe has a tunable force range and the indentation force can be adjusted externally to match tissue limitations. The performance of the probe developed was validated using simulated soft tissues samples. Our tumor
identification experiments showed that the probe can accurately identify the location and size of tumors hidden inside
non-flat tissue surfaces. Further, the probe has clearly demonstrated its potential to identify tumors with tumor-tissue
stiffness ratios as low as 2:1."
This paper presents a novel approach to force sensing by integrating prismatic-tip optical fibers... more This paper presents a novel approach to force sensing by integrating prismatic-tip optical fibers with an orthoplanar spring structure. The complete force sensing solution integrating the prismatic-tip-based sensing concept with an orthoplanar spring mechanism to convert applied forces into a well-delivered displacement whose magnitude can be measured using the optical sensing technique is introduced in this paper. To the best knowledge of the authors, this is the first time that such a force sensing concept has been proposed and studied. The compact force sensor prototype described in this paper demonstrates its capability and feasibility in performing force measurement over a range of 0--2.8 N. The combination of the novel concepts of prismatic-tip optical fiber sensing and the planar spring minimizes the thickness of the sensing device. Due to its simple sensing structure, the sensor is easy to manufacture and can be miniaturized for applications in dexterous robotic handling and the aerospace industry. The proposed sensor is made of nonmetallic materials and operates without the need of electronics components in the sensing area; thus, the sensor is not susceptible to electric or magnetic fields.
Proceedings of the Institution ofMechanical Engineers, Part H: Journal of Engineering in Medicine
"This paper presents a novel wheeled probe for the purpose of aiding a surgeon in soft tissue abn... more "This paper presents a novel wheeled probe for the purpose of aiding a surgeon in soft tissue abnormality identification during minimally invasive surgery (MIS), compensating the loss of haptic feedback commonly associated with MIS. Initially, a prototype for validating the concept was developed. The wheeled probe consists of an indentation depth sensor employing an optic fibre sensing scheme and a force/torque senor. The two sensors work in unison allowing the wheeled probe to measure the tool-tissue interaction force and the rolling indentation depth concurrently. The indentation depth sensor was developed and initially
tested on a homogenous silicone phantom representing a good model for a soft-tissue organ;
the results show that the sensor can accurately measure the occurring indentation depths
whilst performing rolling indentation and has a good repeatability. To validate the ability of
the wheeled probe to identify abnormalities located in the tissue, the device was tested on a
silicone phantom containing embedded hard nodules. The experimental data demonstrate that
recording the tissue reaction force as well as rolling indentation depth signals during rolling indentation, the wheeled probe can rapidly identify the distribution of tissue stiffness and
cause the embedded hard nodules accurately located."
This paper presents a novel optical fiber based
rolling indentation probe designed to measure t... more This paper presents a novel optical fiber based
rolling indentation probe designed to measure the stiffness
distribution of a soft tissue while rolling over the tissue surface
during minimally invasive surgery. By fusing the measurements
along rolling paths, the probe can generalize a mechanical
image to visualize the stiffness distribution within the internal
tissue structure. Since tissue abnormalities are often firmer than
the surrounding organ or parenchyma, a surgeon then can
localize abnormalities by analyzing the image.
The performance of the developed probe was validated using
simulated soft tissues. Results show that the probe can measure
the both force and indentation depth accurately with different
orientations when the probe approached to and rolled on the
tissue surface. In addition, experiments for tumor identification
through rolling indentation were conducted. The size and
embedded depth of the tumor as well as the stiffness ratio
between the tumor and tissue were varied during tests. Results
demonstrate that the probe can effectively and accurately
identify the embedded tumors.
... and trained to cope with complex characteristics in-cluding nonlinearity, system uncertainty,... more ... and trained to cope with complex characteristics in-cluding nonlinearity, system uncertainty, and joint ... be ster-ilized by a standard autoclave process but is compatible with an ... The microgripper's structure is directly coupled with a piezoelectric actuator providing the capability ...
IEEE Transactions Automation Science and Engineering, 2007
... This human-oriented approach based on offline analysis of the raw images is highly ... The in... more ... This human-oriented approach based on offline analysis of the raw images is highly ... The information extracted is transformed into a signature space where de-fective and ... of pipe surface defects from digitized video using image analysis pattern recognition and neural networks ...
This paper proposes a novel approach for the identification of tissue properties in-vivo using a ... more This paper proposes a novel approach for the identification of tissue properties in-vivo using a force sensitive wheeled probe. The purpose of such a device is to compensate a surgeon for a portion of the loss of haptic and tactile feedback experienced during robotic-assisted minimally invasive surgery. Initially, a testing facility for validating the concept ex-vivo was developed and used to characterize two different testing modalities - static (1-DOF) tissue indentation and rolling (2-DOF) tissue indentation. As part of the static indentation experiments a mathematical model was developed to classify tissue condition based on changes in mechanical response. The purpose of the rolling indentation tests was to detect tissue abnormalities, such as tumors, which are difficult to isolate under static testing conditions. During such tests, the test-rig was capable of detecting simulated miniature buried masses at depths of 12mm. Based on these experiments a portable device capable of carrying out similar tests in-vivo was developed. The device was designed to be operated through a trocar port and its key feature is the ability to transition between static indentation and rolling indentation modalities without retracting and changing the tool.
This paper presents the development and evaluation of a miniature, three-axis, fiber-optic force ... more This paper presents the development and evaluation of a miniature, three-axis, fiber-optic force sensor. The sensor is manufactured using low-cost, high-resolution rapid prototyping techniques and is integrated with a catheter to enable the detection of force during MRI-guided cardiac ablation procedures. The working principle is based on reflective light-intensity modulation. A force sensitive structure (flexure) is employed to vary the distance and orientation of an integrated reflector when a force is applied at the catheter tip. In this way, the light is modulated accordingly and the force can be calculated. The sensor has a high sensitivity and an adequate linear response along all three orthogonal axes (Fx, Fy, and Fz) and a working range of around 0.5 N. Low-noise, high-gain electronics provide a force resolution of less than 1 gm force. Experiments demonstrate the ability of the sensor to acquire accurate force readings in a dynamic environment. MRI-compatibility experiments are performed in a clinical 1.5-T MR scanner.
IEEE transactions on bio-medical engineering (TBME), 2013
This paper presents a novel MR-compatible 3-DOF cardiac catheter steering mechanism. The catheter... more This paper presents a novel MR-compatible 3-DOF cardiac catheter steering mechanism. The catheter's steerable structure is tendon driven and consists of miniature deflectable, helical segments created by a precise rapid prototyping technique. The created catheter prototype has an outer diameter of 9 Fr (3 mm) and a steerable distal end that can be deflected in 3D space via four braided high-tensile Spectra® fiber tendons. Any longitudinal twist commonly observed in helical structures is compensated for by employing clockwise (CW) and counter clockwise (CCW) helical segments in an alternating fashion. A 280 μm flexible carbon fiber rod is used as a backbone in a central channel to improve the structure's steering and positioning repeatability. In addition to the backbone, a carbon fiber tube can be inserted into the structure to a varying amount capable of changing the structure's forcibility and, thus, providing a means to change the curvature and to modify the deflectable length of the catheter leading to an extension of reachable points in the catheter-tip workspace. A unique feature of this helical segment structure is that the stiffness can be further adjusted by appropriately tensioning tendons simultaneously. An experimental study has been conducted examining the catheter-tip trajectory in 3D space and its positioning repeatability using a 5-DOF magnetic coil tracking system. Furthermore, MRI experiments in a 1.5 Tesla scanner confirmed the MR-compatibility of the catheter prototype. The study shows that the proposed concept for catheter steering has great potential to be employed for robotically steered and MRguided cardiac catheterization.
IEEE Transactions on Biomedical Engineering (TBME), 2013
"This paper presents a novel palpation probe based on optical fiber technology. It is des... more "This paper presents a novel palpation probe based on optical fiber technology. It is designed to measure stiffness distribution of a soft tissue while sliding over the tissue surface in a near frictionless manner. A novelty of the probe is its ability to measure indentation depth for non-planar tissue profiles which are commonly experienced during surgery. Since tumors are often harder than the surrounding tissue, the proposed probe can intra-operatively aid the surgeon to rapidly identify the presence, location and size of the tumors through the generation of a tissue stiffness map. The probe can concurrently measure tissue reaction force, indentation depth and the orientation of the probe with respect to the tissue surface. Hence it can generate an elasticity model of the tissue with minimum measurement inaccuracies caused by surface profile variations. Further, the probe has a tunable force range and the indentation force can be adjusted externally to match tissue limitations. The performance of the probe developed was validated using simulated soft tissues samples. Our tumor
identification experiments showed that the probe can accurately identify the location and size of tumors hidden inside
non-flat tissue surfaces. Further, the probe has clearly demonstrated its potential to identify tumors with tumor-tissue
stiffness ratios as low as 2:1."
This paper presents a novel approach to force sensing by integrating prismatic-tip optical fibers... more This paper presents a novel approach to force sensing by integrating prismatic-tip optical fibers with an orthoplanar spring structure. The complete force sensing solution integrating the prismatic-tip-based sensing concept with an orthoplanar spring mechanism to convert applied forces into a well-delivered displacement whose magnitude can be measured using the optical sensing technique is introduced in this paper. To the best knowledge of the authors, this is the first time that such a force sensing concept has been proposed and studied. The compact force sensor prototype described in this paper demonstrates its capability and feasibility in performing force measurement over a range of 0--2.8 N. The combination of the novel concepts of prismatic-tip optical fiber sensing and the planar spring minimizes the thickness of the sensing device. Due to its simple sensing structure, the sensor is easy to manufacture and can be miniaturized for applications in dexterous robotic handling and the aerospace industry. The proposed sensor is made of nonmetallic materials and operates without the need of electronics components in the sensing area; thus, the sensor is not susceptible to electric or magnetic fields.
Proceedings of the Institution ofMechanical Engineers, Part H: Journal of Engineering in Medicine
"This paper presents a novel wheeled probe for the purpose of aiding a surgeon in soft tissue abn... more "This paper presents a novel wheeled probe for the purpose of aiding a surgeon in soft tissue abnormality identification during minimally invasive surgery (MIS), compensating the loss of haptic feedback commonly associated with MIS. Initially, a prototype for validating the concept was developed. The wheeled probe consists of an indentation depth sensor employing an optic fibre sensing scheme and a force/torque senor. The two sensors work in unison allowing the wheeled probe to measure the tool-tissue interaction force and the rolling indentation depth concurrently. The indentation depth sensor was developed and initially
tested on a homogenous silicone phantom representing a good model for a soft-tissue organ;
the results show that the sensor can accurately measure the occurring indentation depths
whilst performing rolling indentation and has a good repeatability. To validate the ability of
the wheeled probe to identify abnormalities located in the tissue, the device was tested on a
silicone phantom containing embedded hard nodules. The experimental data demonstrate that
recording the tissue reaction force as well as rolling indentation depth signals during rolling indentation, the wheeled probe can rapidly identify the distribution of tissue stiffness and
cause the embedded hard nodules accurately located."
This paper presents a novel optical fiber based
rolling indentation probe designed to measure t... more This paper presents a novel optical fiber based
rolling indentation probe designed to measure the stiffness
distribution of a soft tissue while rolling over the tissue surface
during minimally invasive surgery. By fusing the measurements
along rolling paths, the probe can generalize a mechanical
image to visualize the stiffness distribution within the internal
tissue structure. Since tissue abnormalities are often firmer than
the surrounding organ or parenchyma, a surgeon then can
localize abnormalities by analyzing the image.
The performance of the developed probe was validated using
simulated soft tissues. Results show that the probe can measure
the both force and indentation depth accurately with different
orientations when the probe approached to and rolled on the
tissue surface. In addition, experiments for tumor identification
through rolling indentation were conducted. The size and
embedded depth of the tumor as well as the stiffness ratio
between the tumor and tissue were varied during tests. Results
demonstrate that the probe can effectively and accurately
identify the embedded tumors.
... and trained to cope with complex characteristics in-cluding nonlinearity, system uncertainty,... more ... and trained to cope with complex characteristics in-cluding nonlinearity, system uncertainty, and joint ... be ster-ilized by a standard autoclave process but is compatible with an ... The microgripper's structure is directly coupled with a piezoelectric actuator providing the capability ...
IEEE Transactions Automation Science and Engineering, 2007
... This human-oriented approach based on offline analysis of the raw images is highly ... The in... more ... This human-oriented approach based on offline analysis of the raw images is highly ... The information extracted is transformed into a signature space where de-fective and ... of pipe surface defects from digitized video using image analysis pattern recognition and neural networks ...
This paper proposes a novel approach for the identification of tissue properties in-vivo using a ... more This paper proposes a novel approach for the identification of tissue properties in-vivo using a force sensitive wheeled probe. The purpose of such a device is to compensate a surgeon for a portion of the loss of haptic and tactile feedback experienced during robotic-assisted minimally invasive surgery. Initially, a testing facility for validating the concept ex-vivo was developed and used to characterize two different testing modalities - static (1-DOF) tissue indentation and rolling (2-DOF) tissue indentation. As part of the static indentation experiments a mathematical model was developed to classify tissue condition based on changes in mechanical response. The purpose of the rolling indentation tests was to detect tissue abnormalities, such as tumors, which are difficult to isolate under static testing conditions. During such tests, the test-rig was capable of detecting simulated miniature buried masses at depths of 12mm. Based on these experiments a portable device capable of carrying out similar tests in-vivo was developed. The device was designed to be operated through a trocar port and its key feature is the ability to transition between static indentation and rolling indentation modalities without retracting and changing the tool.
Flexible manipulators have promising applications in
minimally invasive surgery as it allows th... more Flexible manipulators have promising applications in
minimally invasive surgery as it allows the surgical tools reach
targets which are prohibited by conventional rigid surgical
instrument. However one of the technical difficulties of
implementing the flexible manipulator is to measure the
bending curvature. This paper proposes the design of a novel
optical sensor for measuring the bending curvature of a flexible
manipulator based on light intensity modulation. The sensor is
low cost and is temperature independent. A theoretical model of
using the sensor design to deduce the curvature of a flexible
robot has been created. Implementing the proposed theoretical
model, the developed sensor has been used to measure the bend
of a section of a flexible segment. Validation tests have been
carried out; the results demonstrate that the developed sensor
has good accuracy in measuring the bending angles, the
orientation of the bending and the bending radius.
ASME 2013 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC 2013), 2013
In the field of soft robotics, granular jamming is a newly
adopted variable stiffness mechanism ... more In the field of soft robotics, granular jamming is a newly
adopted variable stiffness mechanism involving the use of vacuum pressure to control soft, particulate matter to become a unified, solid-like structure. However, granular jamming is conventionally controlled with air, which reduces the mobility of the robot. This is because the compressibility of air requires large vacuum pumps or chambers. Instead, we propose the use of an incompressible fluid, such as water, to control the stiffness of the mechanism. This paper presents comparative studies that shows that a hydraulic granular jammed joint using deaired water can both achieve the same stiffness level with just one twentieth of the volume extraction and maintain the same hysteresis level of an air-based system.
Successful and safe laparoscopic surgery is heavily
dependent on its vision system, ... more Successful and safe laparoscopic surgery is heavily
dependent on its vision system, with the primary emphasis on the viewing angle and image stability. Laparoscopic cameras, such as the Storz 10 mm laparoscope, are typically long, rigid tubes which have poor accessbility to target areas and require a second surgeon to operate. With a shifting enthusiasm for natural orifice translumenal endoscopic surgery
(NOTES), most groups prefer flexible endoscopes over the traditional rigid laparoscopes. However, these endoscopes were originally designed for intralumenal use, and tend to be application specific. Thus, there is a technological and clinical need for a small, flexible camera designed for NOTES and other minimally invasive surgical procedures. It has been suggested that camera systems for NOTES also be deployable, as
flexible endoscopes occupy port space, hindering the
use for additional tools. These tools, like the Olympus GIF TYPE 160, can be 8.6 mm in diameter, occupying over half of a 12 mm port. Deployable camera systems such as Pillcam, are unable to provide real time control due to their wireless connectivity. The Core-Snake aims to bridge these gaps. The CoreSnake is a 10 mm diameter robot which can alter its
body stiffness from being flexible to rigid via granular jamming.
35th International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2013), 2013
Granular jamming consists of constraining a large quantity of small particles within a membrane, ... more Granular jamming consists of constraining a large quantity of small particles within a membrane, similar to the use of hydrostatic and muscle forces in invertebrates to stiffen their bodies. However, current works on jamming have not examined the effect of coupling particles together, akin to connective tissue in animals. We present a study which provides a comparison between coupled and decoupled granules when jammed for a
dexterous robotic limb.
3rd Joint Workshop on New Technologies for Computer/Robot Assisted Surgery (CRAS 2013), 2013
"We are presenting a new concept for a robot arm
design that can change its structure from... more "We are presenting a new concept for a robot arm
design that can change its structure from complete soft to stiff. The proposed system makes use of the principle of granular jamming: A granule-filled membrane is soft and flexible when the pressure inside the membrane is higher or equal to the outside pressure; however, lowering the pressure inside below the outside pressure jams granules into each other, hence, increasing the stiffness of the structure. Employing this principle, we create low cost, variable stiffness manipulation systems that have great application potential, as for example in the field of minimally invasive surgery. Employing granular jamming, our approach can be used to create controllable-stiffness tools covering the whole spectrum of current surgical manipulation devices – from laparoscopes (straight and rigid) to endoscopes (flexible and soft). Combining the granular jamming manipulation system with end effector tools such as a camera or a gripper, this overall system can fit through a Trocar port and bend around organs in a patient’s abdominal cavity providing the surgeon with improved views or a retraction aid."
Robot grasping and manipulation require very
accurate knowledge of the object’s location within ... more Robot grasping and manipulation require very
accurate knowledge of the object’s location within the robotic
hand. By itself, a vision system cannot provide very precise and
robust pose tracking due to occlusions or hardware limitations.
This paper presents a method to estimate a grasped object’s
6D pose by fusing sensor data from vision, tactile sensors and
joint encoders. Given an initial pose acquired by the vision
system and the contact locations on the fingertips, an iterative
process optimises the estimation of the object pose by finding
a transformation that fits the grasped object to the finger
tips. Experiments were carried out in both simulation and a
real system consisting of a Shadow arm and hand with ATI
Force/Torque sensors instrumented on the fingertips and a
Microsoft Kinect camera. In order to make the method suitable
for real-time applications, the performance of the algorithm was
investigated in terms of speed and accuracy of convergence.
IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2012), 2012
Robotic manipulators for minimally invasive surgeries have traditionally been rigid, with a steer... more 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.
We propose a novel, high degree of freedom variable stiffness joint for use in a miniature snake-... more We propose a novel, high degree of freedom variable stiffness joint for use in a miniature snake-like robot for minimally invasive surgeries via granular jamming. By pulling granule filled membrane-columns under vacuum, the columns and joint stiffen
as the granular matter begin to jam. In our experiments, we achieved a four-fold increase in stiffness, and the stiffness can be achieved while the columns are straight or bent. Current flexible
manipulators in industrial and medical robotics have followed two dominating methods of actuation and stiffness control. The first method is the continuum manipulator, which utilizes tendons or rods to bend the manipulator in a continuous fashion. The second method is classified as the highly articulated robot, where the manipulator is comprised of multiple segments linked by motor
driven universal joints. Like the latter, our manipulator is highly articulated, however stiffness of each joint can be independently
controlled by the granular jamming principle. This paper studies the effect of grain type and vacuum pressure for stiffness tuning.
We found that granules with a matte surface were able to achieve higher stiffnesses, with a cube shape exhibiting the highest stiffness, but at the cost of high levels of hysteresis.
IEEE Int. Conf. Robotics and Automation (ICRA 2012), 2012
This paper introduces a new and low-cost tissue stiffness simulation technique for sur... more This paper introduces a new and low-cost tissue stiffness simulation technique for surgical training and robot assisted minimally invasive surgery (RMIS) with pseudo-haptic feedback based on tissue stiffness maps provided by rolling mechanical imaging. Superficial palpation and deep palpation pseudo-haptic simulation methods are presented. Although without expensive haptic interfaces users receive only visual feedback (pseudo-haptics) when maneuvering a cursor over the surface of a virtual soft-tissue organ by means of an input device such as a mouse, a joystick, or a touch-sensitive tablet, the alterations to the cursor behavior induced by the method creates the experience of actual interaction with a tumor in the
users’ minds. The proposed methods are experimentally
evaluated for tissue abnormality identification. It is shown that
users can recognize tumors with these two methods and the rate
of correctly recognized tumors in deep palpation pseudo-haptic
simulation is higher than superficial palpation simulation.
IEEE Int. Conf. Robotics and Automation (ICRA 2012), 2012
This paper introduces a new and low-cost tissue stiffness simulation technique for sur... more This paper introduces a new and low-cost tissue stiffness simulation technique for surgical training and robot assisted minimally invasive surgery (RMIS) with pseudo-haptic feedback based on tissue stiffness maps provided by rolling mechanical imaging. Superficial palpation and deep palpation pseudo-haptic simulation methods are presented. Although without expensive haptic interfaces users receive only visual feedback (pseudo-haptics) when maneuvering a cursor over the surface of a virtual soft-tissue organ by means of an input device such as a mouse, a joystick, or a touch-sensitive tablet, the alterations to the cursor behavior induced by the method creates the experience of actual interaction with a tumor in the
users’ minds. The proposed methods are experimentally
evaluated for tissue abnormality identification. It is shown that
users can recognize tumors with these two methods and the rate
of correctly recognized tumors in deep palpation pseudo-haptic
simulation is higher than superficial palpation simulation.
The primary goal of this paper is to present a novel optical fiber based air float palpation... more The primary goal of this paper is to present a novel optical fiber based air float palpation probe designed to measure stiffness
variation of a soft tissue while rolling over the tissue surface in any direction in a near frictionless manner. The probe can concurrently measure the indentation depth and surface profile variations and experiments carried out using simulated soft tissues showed that the probe can accurately identify tumors embedded inside non-flat tissue surfaces.
This paper presents a novel approach to measuring the indentation depth of a stiffnes... more This paper presents a novel approach to measuring the indentation depth of a stiffness sensor in real time during a soft tissue palpation activity. The proposed system is integrated into a stiffness probe and is designed to intra-operatively aid the surgeon to rapidly identify the tissue abnormalities with minimum measurement inaccuracies due to tissue surface profile variations. Stiffness probe and the associated surface profile sensors are pneumatic and the newly
designed system can concurrently measure the indentation
depth and surface profile variations while sliding over the soft
tissues in any direction in a near frictionless manner. With the
pneumatic pressure maintained constant, the displacement of
the sensing element is a direct function of the stiffness of the tissue under investigation. The sensor has a tunable force range and the indentation force can be adjusted externally to match tissue limitations.
The prototype of the new design of stiffness probe was calibrated and tested on silicone blocks simulating soft tissue.
The results show that this sensor can measure indentation depth more accurately than air cushion probe alone. The structure, working principle, and a mathematical model for this new design are described.
30th World Congress of Endourology and SWL (WCE 2012), 2012
Granular jamming is a phenomena where particles can change state based on the amount of ext... more Granular jamming is a phenomena where particles can change state based on the amount of external stress applied. In our case, the pressure differential between the inside and outside of the membrane (vacuuming the internal pressure) is used to regulate the granules between a soft, fluid-like state to a rigid, solid-like state.
This paper investigates novel tactile sensing concepts of a fiber optic sensor that c... more This paper investigates novel tactile sensing concepts of a fiber optic sensor that can be integrated with minimally invasive surgical (MIS) manipulation tools whilst being Magnetic Resonance (MR) compatible. A 3x3 tactile optical fiber sensor was developed, and is able to measure applied normal forces. Forces are converted from the deflections of a set of nine flexures that are connected to a system of mirrors which, in turn, reflect light received from transmitting fibers to detection fibers. The changes in light intensity are ultimately read-out by a camera system. The images received by the camera attached at the end of the detection fibers are then processed on a computer system using Matlab. Employing a calibration process, the applied forces can be related to the number of activated pixels per received fiber image. This system enables an array of tactile flexures to be recorded via a single camera.
We describe a novel approach for the localization of tissue abnormalities during minimally inv... more We describe a novel approach for the localization of tissue abnormalities during minimally invasive surgery (MIS) using a force sensitive wheeled probe. The concept is to fuse the kinaesthetic information from the wheel-tissue rolling interaction into a pseudo-color rolling mechanical image (RMI) to visualize the spatial variation of stiffness within the internal tissue structure. Since tissue abnormalities are often firmer than the surrounding organ or parenchyma, a surgeon then can localize abnormalities by analyzing the image. Initially, a testing facility for validating the concept in an ex vivo setting was developed and used to investigate rolling “wheel-tissue” interaction. A silicone soft tissue phantom with embedded hard nodules was constructed to allow for experimental comparison between a RMI and a known soft tissue structure. Tests have also been performed on excised porcine organs to show the efficacy of the method when applied to biological soft tissues. Results indicate that the RMI technique is particularly suited to identifying the stiffness distribution within a tissue sample, as the continuous force measurement along a given rolling trajectory provides repeatable information regarding relative variations in the normal tissue response. When compared to multiple discrete uniaxial indentations, the continuous measurement approach of RMI is shown to be more sensitive and facilitates coverage of a large area in a short period of time. Furthermore, if parametric classification of tissue properties based on a uniaxial tissue indentation model is desirable, the rolling indentation probe can be easily employed as a uniaxial indenter.
AbstractThis paper describes a novel design of a 3-axis force sensor which can be applied in mag... more AbstractThis paper describes a novel design of a 3-axis force sensor which can be applied in magnetic resonance (MR) workspaces such as that of a magnetic resonance imaging (MRI) machine. The sensor operates based on an optical sens-ing principle to measure ...
The authors have recently proposed the method of
rolling indentation over soft tissue to rapidl... more The authors have recently proposed the method of
rolling indentation over soft tissue to rapidly identify soft tissue
properties for localization and detection of tissue abnormalities,
with the aim of compensating for the loss of haptics
information experienced during robotic-assisted minimally
invasive surgery (RMIS). This paper investigates the concept of
rolling indentation using Finite Element modeling. To obtain
ground truth data, rolling indentation experiments are
conducted on a silicone phantom which contains three
simulated tumours. The tissue phantom is modeled as
hyperelastic material using ABAQUS^TM. The identification of
tumours includes two parts: firstly,when the spatial location of
tumour is known, identify the tumour’s mechanical properties
(initial shear modulus); secondly if the mechanical properties
of tumour are known, identify the tumour’s spatial location.
The results show that the proposed method can identify
information of tumours accurately and robustly. The identified
tumour mechanical properties and tumour locations are in
good agreement with experimental measurements.
AbstractThis paper proposes a novel technique to estimate slips and velocities of an unmanned sk... more AbstractThis paper proposes a novel technique to estimate slips and velocities of an unmanned skid-steered vehicle. An optical flow-based visual sensor looking down the terrain surface is employed to recover the motion of the vehicle by tracking features selected from the ...
Abstract This paper describes the preliminary design and construction of an optical fiber sensor ... more Abstract This paper describes the preliminary design and construction of an optical fiber sensor which has been developed for evaluating the feasibility of using an optical-based force sensing methodology to investigate mechanical soft tissue properties during minimally invasive surgery. This sensor applies a novel reflective light intensity modulation scheme using bent-tip optical fibers and a reflector to measure mechanical response of the soft tissue when it interacts with the sensor. By adopting such optical fibers to detect minute ...
Intelligent Robots and Systems, 2003. (IROS 2003). Proceedings. 2003 IEEE/RSJ International Conference on , 2003
Abstract - Threaded fastenings are a common assembly method, and account for over a quarter of al... more Abstract - Threaded fastenings are a common assembly method, and account for over a quarter of all assembly operations. These operations are very difficult to automate, with threaded to align and position the screw with respect to the hole, and to apply axial toque until the ...
Intelligent Robots and Systems, 2002. IEEE/RSJ International Conference on , 2002
This paper presents an integrated physics based model for a front end mobile excavator. The model... more This paper presents an integrated physics based model for a front end mobile excavator. The model describes the dynamic relationship between the operator input commands and the position, orientation, speed and forces of the vehicle and the excavation arm. The dynamic model has the potential to be used in advanced controller design for automated excavation systems. The dynamic model for
Ieee International Conference on Robotics and Automation (Icra),, 2006
... UK Email: yahya.zweiri@kcl.ac.uk Lakmal D Seneviratne and Kaspar Althoefer Department of Mech... more ... UK Email: yahya.zweiri@kcl.ac.uk Lakmal D Seneviratne and Kaspar Althoefer Department of Mechanical Engineering King's College London Strand, London WC2R 2LS, UK Abstract Accurate estimation of slip is essential ...
Industrial Technology, 2002. IEEE ICIT '02. 2002 IEEE International Conference on , 2002
Threaded fastenings are a common assembly method, accounting for over a quarter of all assembly o... more Threaded fastenings are a common assembly method, accounting for over a quarter of all assembly operations. Threaded fastenings are popular because they permit easy disassembly for maintenance, repair, relocation and recycling. Screw insertions are typically carried out manually and are a difficult problem to automate. As a result there is very little published research on automating threaded fastenings, and most research on automated assembly focus on the peg-in-hole assembly problem. This paper investigates the problem of automated monitoring of the screw insertion process. The monitoring problem deals with predicting the integrity of a threaded insertion, based on the torque vs. insertion depth curve generated during the insertion. The authors have developed an analytical model to predict the torque signature signals during self-tapping screw insertions. However, the model requires parameters on the screw dimensions and plate material properties, and some of these parameters are difficult to obtain. This paper presents a study on on-line parameter estimation during screw fastenings. A methodology for estimating the friction properties and screw-diameter during a general self-tapping screw insertion process is presented. It is shown that friction and screw-diameter required by the model can be reliably estimated on-line. Computer simulation results, with and without simulation noise are presented to validate the estimation procedure.
IEEE International Conference on Robotics and Automation (ICRA 2007), 2007
"Object surface properties are among the most
important information which a robot re... more "Object surface properties are among the most
important information which a robot requires in order to
effectively interact with an unknown environment. This paper
presents a novel haptic exploration strategy for recognizing the
physical properties of unknown object surfaces using an
intelligent finger. This developed intelligent fingeris capable of
identifying the contact location, normal and tangential force,
and the vibrations generated from the contact in real time. In
the proposed strategy, this finger gently slides along the surface
with a short stroke while increasing and decreasing thesliding
velocity. By applying a dynamic friction model to describe this
contact, rich and accurate surface physical properties can be
identified within this stroke. This allows different surface
materials to be easily distinguished even if when theyhave very
similar texture. Several supervised learning algorithms have
been applied and compared for surface recognition based on
the obtained surface properties. It has been found that the
naïve Bayes classifier is superior to radial basis function
network and k-NN method, achieving an overall classification
accuracy of 88.5% for distinguishing twelve different surface
materials."
"This paper proposes a novel nonlinear viscoelastic soft tissue model generated from ex vivo expe... more "This paper proposes a novel nonlinear viscoelastic soft tissue model generated from ex vivo experimental results on ovine liver using a force sensitive probe. In order to study the bio-mechanics of soft tissue, static indentation tests were applied on ovine liver. An empirical constitutive equation was extracted from the examined data. A mechanical model combining linear viscoelasticity with a nonlinear function of strain–stress is proposed. The developed model has been evaluated both statically and dynamically with different strain rates – i.e. where the velocity of indentation is varied. By comparing simulation results and measured experimental data, it has been concluded that the proposed model is robust for modelling both static and dynamic indentation conditions.
The effect of changing boundary conditions on the parameters in the proposed model has been studied by choosing test sites with different underlying tissue thicknesses. The results indicate that for small strain, the effect of the thickness condition is reasonable to be neglected.
The absence of touch of sense is a widely known drawback of robotic minimally invasive surgery (M... more The absence of touch of sense is a widely known drawback of robotic minimally invasive surgery (MIS). This paper proposes a design of optic soft tactile arrays which is promising to be adapted for MIS. The proposed design consists of multiple soft material channels. Each channel is designed using the Bernoulli pipe structure to amplify the sensor's sensitivity through input and output diameter difference. A multi-core optic fiber cable and a camera are used to capture the change of light intensity caused by the contact forces applied onto the individual soft material channels. The proposed sensor has the following advantages: 1) making use of 3D printing and soft material casting, it is suitable for designing sensors with high density of tactile elements; 2) it also allows the sensor to be designed in an arbitrary shape to fit various MIS applications; 3) compared to other light-intensity based tactile sensor, it is easy to fabricate and miniaturize; it avoids the complexity of attaching reflectors to individual sensing elements; 4) it is immune to electromagnetic interference. In this paper, a prototype which has 3×3 tactile elements in an area of 9.5 × 11 mm2 has been developed and test for feasibility study. Also, a noise-filtering algorithm is developed to reduce the imaging noise. Validation experiments were carried out and results show that the average measurable force range for a single tactile element is 0 to 1.622N with an average accuracy of 97%. The sensor has low crosstalk-to-signal ratio, 1.8% on average, and has no signal drift over time.
Volume 5A: 39th Mechanisms and Robotics Conference
Flexible robot arms have been developed for various medical and industrial applications because o... more Flexible robot arms have been developed for various medical and industrial applications because of their compliant structures enabling safe environmental interactions. This paper introduces a novel flexible robot arm comprising a number of elastically deformable planar spring elements arranged in series. The effects of flexure design variations on their layer compliance properties are investigated. Numerical studies of the different layer configurations are presented and finite Element Analysis (FEA) simulation is conducted. Based on the suspended platform’s motion of each planar spring, this paper then provides a new method for kinematic modeling of the proposed robot arm. The approach is based on the concept of simultaneous rotation and the use of Rodrigues’ rotation formula and is applicable to a wide class of continuum-style robot arms. At last, the flexible robot arms respectively integrated with two different types of compliance layers are prototyped. Preliminary test results ...
Transactions of Japanese Society for Medical and Biological Engineering, 2013
2 Granular jamming consists of constraining a large quantity of small particles within a membrane... more 2 Granular jamming consists of constraining a large quantity of small particles within a membrane, similar to the use of hydrostatic and muscle forces in invertebrates to stiffen their bodies. However, current works on jamming have not examined the effect of coupling particles together, akin to connective tissue in animals. We present a study which provides a comparison between coupled and decoupled granules when jammed for a dexterous robotic limb.
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Journal Papers by Kaspar Althoefer
identification experiments showed that the probe can accurately identify the location and size of tumors hidden inside
non-flat tissue surfaces. Further, the probe has clearly demonstrated its potential to identify tumors with tumor-tissue
stiffness ratios as low as 2:1."
tested on a homogenous silicone phantom representing a good model for a soft-tissue organ;
the results show that the sensor can accurately measure the occurring indentation depths
whilst performing rolling indentation and has a good repeatability. To validate the ability of
the wheeled probe to identify abnormalities located in the tissue, the device was tested on a
silicone phantom containing embedded hard nodules. The experimental data demonstrate that
recording the tissue reaction force as well as rolling indentation depth signals during rolling indentation, the wheeled probe can rapidly identify the distribution of tissue stiffness and
cause the embedded hard nodules accurately located."
rolling indentation probe designed to measure the stiffness
distribution of a soft tissue while rolling over the tissue surface
during minimally invasive surgery. By fusing the measurements
along rolling paths, the probe can generalize a mechanical
image to visualize the stiffness distribution within the internal
tissue structure. Since tissue abnormalities are often firmer than
the surrounding organ or parenchyma, a surgeon then can
localize abnormalities by analyzing the image.
The performance of the developed probe was validated using
simulated soft tissues. Results show that the probe can measure
the both force and indentation depth accurately with different
orientations when the probe approached to and rolled on the
tissue surface. In addition, experiments for tumor identification
through rolling indentation were conducted. The size and
embedded depth of the tumor as well as the stiffness ratio
between the tumor and tissue were varied during tests. Results
demonstrate that the probe can effectively and accurately
identify the embedded tumors.
identification experiments showed that the probe can accurately identify the location and size of tumors hidden inside
non-flat tissue surfaces. Further, the probe has clearly demonstrated its potential to identify tumors with tumor-tissue
stiffness ratios as low as 2:1."
tested on a homogenous silicone phantom representing a good model for a soft-tissue organ;
the results show that the sensor can accurately measure the occurring indentation depths
whilst performing rolling indentation and has a good repeatability. To validate the ability of
the wheeled probe to identify abnormalities located in the tissue, the device was tested on a
silicone phantom containing embedded hard nodules. The experimental data demonstrate that
recording the tissue reaction force as well as rolling indentation depth signals during rolling indentation, the wheeled probe can rapidly identify the distribution of tissue stiffness and
cause the embedded hard nodules accurately located."
rolling indentation probe designed to measure the stiffness
distribution of a soft tissue while rolling over the tissue surface
during minimally invasive surgery. By fusing the measurements
along rolling paths, the probe can generalize a mechanical
image to visualize the stiffness distribution within the internal
tissue structure. Since tissue abnormalities are often firmer than
the surrounding organ or parenchyma, a surgeon then can
localize abnormalities by analyzing the image.
The performance of the developed probe was validated using
simulated soft tissues. Results show that the probe can measure
the both force and indentation depth accurately with different
orientations when the probe approached to and rolled on the
tissue surface. In addition, experiments for tumor identification
through rolling indentation were conducted. The size and
embedded depth of the tumor as well as the stiffness ratio
between the tumor and tissue were varied during tests. Results
demonstrate that the probe can effectively and accurately
identify the embedded tumors.
minimally invasive surgery as it allows the surgical tools reach
targets which are prohibited by conventional rigid surgical
instrument. However one of the technical difficulties of
implementing the flexible manipulator is to measure the
bending curvature. This paper proposes the design of a novel
optical sensor for measuring the bending curvature of a flexible
manipulator based on light intensity modulation. The sensor is
low cost and is temperature independent. A theoretical model of
using the sensor design to deduce the curvature of a flexible
robot has been created. Implementing the proposed theoretical
model, the developed sensor has been used to measure the bend
of a section of a flexible segment. Validation tests have been
carried out; the results demonstrate that the developed sensor
has good accuracy in measuring the bending angles, the
orientation of the bending and the bending radius.
adopted variable stiffness mechanism involving the use of vacuum pressure to control soft, particulate matter to become a unified, solid-like structure. However, granular jamming is conventionally controlled with air, which reduces the mobility of the robot. This is because the compressibility of air requires large vacuum pumps or chambers. Instead, we propose the use of an incompressible fluid, such as water, to control the stiffness of the mechanism. This paper presents comparative studies that shows that a hydraulic granular jammed joint using deaired water can both achieve the same stiffness level with just one twentieth of the volume extraction and maintain the same hysteresis level of an air-based system.
dependent on its vision system, with the primary emphasis on the viewing angle and image stability. Laparoscopic cameras, such as the Storz 10 mm laparoscope, are typically long, rigid tubes which have poor accessbility to target areas and require a second surgeon to operate. With a shifting enthusiasm for natural orifice translumenal endoscopic surgery
(NOTES), most groups prefer flexible endoscopes over the traditional rigid laparoscopes. However, these endoscopes were originally designed for intralumenal use, and tend to be application specific. Thus, there is a technological and clinical need for a small, flexible camera designed for NOTES and other minimally invasive surgical procedures. It has been suggested that camera systems for NOTES also be deployable, as
flexible endoscopes occupy port space, hindering the
use for additional tools. These tools, like the Olympus GIF TYPE 160, can be 8.6 mm in diameter, occupying over half of a 12 mm port. Deployable camera systems such as Pillcam, are unable to provide real time control due to their wireless connectivity. The Core-Snake aims to bridge these gaps. The CoreSnake is a 10 mm diameter robot which can alter its
body stiffness from being flexible to rigid via granular jamming.
dexterous robotic limb.
design that can change its structure from complete soft to stiff. The proposed system makes use of the principle of granular jamming: A granule-filled membrane is soft and flexible when the pressure inside the membrane is higher or equal to the outside pressure; however, lowering the pressure inside below the outside pressure jams granules into each other, hence, increasing the stiffness of the structure. Employing this principle, we create low cost, variable stiffness manipulation systems that have great application potential, as for example in the field of minimally invasive surgery. Employing granular jamming, our approach can be used to create controllable-stiffness tools covering the whole spectrum of current surgical manipulation devices – from laparoscopes (straight and rigid) to endoscopes (flexible and soft). Combining the granular jamming manipulation system with end effector tools such as a camera or a gripper, this overall system can fit through a Trocar port and bend around organs in a patient’s abdominal cavity providing the surgeon with improved views or a retraction aid."
accurate knowledge of the object’s location within the robotic
hand. By itself, a vision system cannot provide very precise and
robust pose tracking due to occlusions or hardware limitations.
This paper presents a method to estimate a grasped object’s
6D pose by fusing sensor data from vision, tactile sensors and
joint encoders. Given an initial pose acquired by the vision
system and the contact locations on the fingertips, an iterative
process optimises the estimation of the object pose by finding
a transformation that fits the grasped object to the finger
tips. Experiments were carried out in both simulation and a
real system consisting of a Shadow arm and hand with ATI
Force/Torque sensors instrumented on the fingertips and a
Microsoft Kinect camera. In order to make the method suitable
for real-time applications, the performance of the algorithm was
investigated in terms of speed and accuracy of convergence.
as the granular matter begin to jam. In our experiments, we achieved a four-fold increase in stiffness, and the stiffness can be achieved while the columns are straight or bent. Current flexible
manipulators in industrial and medical robotics have followed two dominating methods of actuation and stiffness control. The first method is the continuum manipulator, which utilizes tendons or rods to bend the manipulator in a continuous fashion. The second method is classified as the highly articulated robot, where the manipulator is comprised of multiple segments linked by motor
driven universal joints. Like the latter, our manipulator is highly articulated, however stiffness of each joint can be independently
controlled by the granular jamming principle. This paper studies the effect of grain type and vacuum pressure for stiffness tuning.
We found that granules with a matte surface were able to achieve higher stiffnesses, with a cube shape exhibiting the highest stiffness, but at the cost of high levels of hysteresis.
users’ minds. The proposed methods are experimentally
evaluated for tissue abnormality identification. It is shown that
users can recognize tumors with these two methods and the rate
of correctly recognized tumors in deep palpation pseudo-haptic
simulation is higher than superficial palpation simulation.
users’ minds. The proposed methods are experimentally
evaluated for tissue abnormality identification. It is shown that
users can recognize tumors with these two methods and the rate
of correctly recognized tumors in deep palpation pseudo-haptic
simulation is higher than superficial palpation simulation.
variation of a soft tissue while rolling over the tissue surface in any direction in a near frictionless manner. The probe can concurrently measure the indentation depth and surface profile variations and experiments carried out using simulated soft tissues showed that the probe can accurately identify tumors embedded inside non-flat tissue surfaces.
designed system can concurrently measure the indentation
depth and surface profile variations while sliding over the soft
tissues in any direction in a near frictionless manner. With the
pneumatic pressure maintained constant, the displacement of
the sensing element is a direct function of the stiffness of the tissue under investigation. The sensor has a tunable force range and the indentation force can be adjusted externally to match tissue limitations.
The prototype of the new design of stiffness probe was calibrated and tested on silicone blocks simulating soft tissue.
The results show that this sensor can measure indentation depth more accurately than air cushion probe alone. The structure, working principle, and a mathematical model for this new design are described.
rolling indentation over soft tissue to rapidly identify soft tissue
properties for localization and detection of tissue abnormalities,
with the aim of compensating for the loss of haptics
information experienced during robotic-assisted minimally
invasive surgery (RMIS). This paper investigates the concept of
rolling indentation using Finite Element modeling. To obtain
ground truth data, rolling indentation experiments are
conducted on a silicone phantom which contains three
simulated tumours. The tissue phantom is modeled as
hyperelastic material using ABAQUS^TM. The identification of
tumours includes two parts: firstly,when the spatial location of
tumour is known, identify the tumour’s mechanical properties
(initial shear modulus); secondly if the mechanical properties
of tumour are known, identify the tumour’s spatial location.
The results show that the proposed method can identify
information of tumours accurately and robustly. The identified
tumour mechanical properties and tumour locations are in
good agreement with experimental measurements.
important information which a robot requires in order to
effectively interact with an unknown environment. This paper
presents a novel haptic exploration strategy for recognizing the
physical properties of unknown object surfaces using an
intelligent finger. This developed intelligent fingeris capable of
identifying the contact location, normal and tangential force,
and the vibrations generated from the contact in real time. In
the proposed strategy, this finger gently slides along the surface
with a short stroke while increasing and decreasing thesliding
velocity. By applying a dynamic friction model to describe this
contact, rich and accurate surface physical properties can be
identified within this stroke. This allows different surface
materials to be easily distinguished even if when theyhave very
similar texture. Several supervised learning algorithms have
been applied and compared for surface recognition based on
the obtained surface properties. It has been found that the
naïve Bayes classifier is superior to radial basis function
network and k-NN method, achieving an overall classification
accuracy of 88.5% for distinguishing twelve different surface
materials."
The effect of changing boundary conditions on the parameters in the proposed model has been studied by choosing test sites with different underlying tissue thicknesses. The results indicate that for small strain, the effect of the thickness condition is reasonable to be neglected.