Title: A Continuum Lung Stapler Leveraging Phase Changing Metal for Dexterity and Stiffness
Lung cancer claims over 130,000 lives per year in the USA. For those with malignant tumors requiring resection, minimally invasive thoracic surgery via a video assisted or robotic approach is an alternative to highly invasive open thoracotomy (in which the chest is “cracked” open). This involves the insertion of 3-5 ports through the chest wall and the use of a camera and instruments mounted to rigid shafts, which are used to resect tissue in a deflated lung. One of these tools is typically a stapler which is able to simultaneously cut and seal the lung tissue. Tendon-driven continuum robots (TDCRs) are capable of curvilinear motions, which can add useful dexterity in constrained anatomical regions like the chest. However, the inherent flexibility of TDCRs presents challenges for integrating stapler-type end effectors. Lung staplers today are typically rigid tools because they require large axial forces to be transmitted along the tool shaft to fire staples. Such forces would apply large loads to curved continuum devices, changing their shapes and moving the end effector undesirably during staple firing. Low melting point alloys (LMPA) have been explored to stiffen substantially soft robots and compliant surgical devices. Here, we propose their use in a TDCR stapler to stiffen the tool shaft before staples are fired. Prior to stiffening, tendon actuation can provide enhanced maneuverability by curving the backbone compared to rigid staplers to position the stapler at the desired location. more »« less
Nelson, Nicholas; Nelson, Carl A.
(, Frontiers in Biomedical Devices)
null
(Ed.)
Most robots for minimally invasive surgery (MIS) are large, bulky devices which mimic the paradigm of manual MIS by manipulating long, rigid instruments from outside the body [1]. Some of these incorporate “wristed” instruments to place some local dexterity at or near the tool tip [2]. In contrast, a small number of MIS robot designs place all of the degrees of freedom inside the patient’s body in order to increase the local dexterity [3].
Esser, D S; Rox, M F; Naftel, R P; Rucker, D C; Barth, E J; Kuntz, A; Webster_III, R J
(, IEEE transactions on medical robotics and bionics)
Prior models of continuously flexible robots typically assume uniform stiffness, and in this paper we relax this assumption. Geometrically varying stiffness profiles provide additional design freedom to influence the motions and workspaces of continuum robots. These results are timely, because with recent rapid advancements in multimaterial additive manufacturing techniques, it is now straightforward to create more complex stiffness profiles in robots. The key insight of this paper is to project forces and moments applied to the robot onto its center of stiffness (i.e. the Young’s modulus-weighted center of each cross section). We show how the center of stiffness can be thought of as analogous to a “precurved backbone” in a robot with uniform stiffness. This analogy enables a large body of prior work in Cosserat Rod modeling of such robots to be applied directly to those with stiffness variations. We experimentally validate this approach using multimaterial, soft, tendon-actuated robots. Lastly, to illustrate how these results can be used in practice, we investigate how stiffness variation can improve performance in a neurosurgical task.
Orekhov, Andrew L.; Johnston, Garrison L.; Simaan, Nabil
(, 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS))
Continuum robots suffer large deflections due to internal and external forces. Accurate modeling of their passive compliance is necessary for accurate environmental interaction, especially in scenarios where direct force sensing is not practical. This paper focuses on deriving analytic formulations for the compliance of continuum robots that can be modeled as Kirchhoff rods. Compared to prior works, the approach presented herein is not subject to the constant-curvature assumptions to derive the configuration space compliance, and we do not rely on computationally-expensive finite difference approximations to obtain the task space compliance. Using modal approximations over curvature space and Lie group integration, we obtain closed-form expressions for the task and configuration space compliance matrices of continuum robots, thereby bridging the gap between constant-curvature analytic formulations of configuration space compliance and variable curvature task space compliance. We first present an analytic expression for the compliance of aingle Kirchhoff rod.We then extend this formulation for computing both the task space and configuration space compliance of a tendon-actuated continuum robot. We then use our formulation to study the tradeoffs between computation cost and modeling accuracy as well as the loss in accuracy from neglecting the Jacobian derivative term in the compliance model. Finally, we experimentally validate the model on a tendon-actuated continuum segment, demonstrating the model’s ability to predict passive deflections with error below 11.5% percent of total arc length.
Tanaka, Koki; Karimi, Mohammad Amin; Busque, Bruno-Pier; Mulroy, Declan; Zhou, Qiyuan; Batra, Richa; Srivastava, Ankit; Jaeger, Heinrich M.; Spenko, Matthew
(, 2020 3rd IEEE International Conference on Soft Robotics (RoboSoft))
Soft robots employ flexible and compliant materials to perform adaptive tasks and navigate uncertain environments. However, soft robots are often unable to achieve forces and precision on the order of rigid-bodied robots. In this paper, we propose a new class of mobile soft robots that can reversibly transition between compliant and stiff states without reconfiguration. The robot can passively conform or actively control its shape, stiffen in its current configuration to function as a rigid-bodied robot, then return to its flexible form. The robotic structure consists of passive granular material surrounded by an active membrane. The membrane is composed of interconnected robotic sub-units that can control the packing density of the granular material and exploit jamming behaviors by varying the length of the interconnecting cables. Each robotic sub-unit uses a differential drive system to achieve locomotion and self-reconfigurability. We present the robot design and perform a set of locomotion and object manipulation experiments to characterize the robot's performance in soft and rigid states. We also introduce a simulation framework in which we model the jamming soft robot design and study the scalability of this class of robots. The proposed concept demonstrates the properties of both soft and rigid robots, and has the potential to bridge the gap between the two
Bentley, Michael; Rucker, Caleb; Reddy, Chakravarthy; Salzman, Oren; Kuntz, Alan
(, Journal of Medical Robotics Research)
Steerable needles are capable of accurately targeting difficult-to-reach clinical sites in the body. By bending around sensitive anatomical structures, steerable needles have the potential to reduce the invasiveness of many medical procedures. However, inserting these needles with curved trajectories increases the risk of tissue damage due to perpendicular forces exerted on the surrounding tissue by the needle’s shaft, potentially resulting in lateral shearing through tissue. Such forces can cause significant tissue damage, negatively affecting patient outcomes. In this work, we derive a tissue and needle force model based on a Cosserat string formulation, which describes the normal forces and frictional forces along the shaft as a function of the planned needle path, friction model and parameters, and tip piercing force. We propose this new force model and associated cost function as a safer and more clinically relevant metric than those currently used in motion planning for steerable needles. We fit and validate our model through physical needle robot experiments in a gel phantom. We use this force model to define a bottleneck cost function for motion planning and evaluate it against the commonly used path-length cost function in hundreds of randomly generated three-dimensional (3D) environments. Plans generated with our force-based cost show a 62% reduction in the peak modeled tissue force with only a 0.07% increase in length on average compared to using the path-length cost in planning. Additionally, we demonstrate planning with our force-based cost function in a lung tumor biopsy scenario from a segmented computed tomography (CT) scan. By directly minimizing the modeled needle-to-tissue force, our method may reduce patient risk and improve medical outcomes from steerable needle interventions.
Esser, Daniel S, Ertop, Tayfun Efe, McCabe, Emily, Maldonado, Fabien, Gillaspie, Erin A, Kuntz, Alan, and Webster_III, Robert J. A Continuum Lung Stapler Leveraging Phase Changing Metal for Dexterity and Stiffness. Retrieved from https://par.nsf.gov/biblio/10547470. Web. doi:10.31256/HSMR2024.31.
Esser, Daniel S, Ertop, Tayfun Efe, McCabe, Emily, Maldonado, Fabien, Gillaspie, Erin A, Kuntz, Alan, & Webster_III, Robert J. A Continuum Lung Stapler Leveraging Phase Changing Metal for Dexterity and Stiffness. Retrieved from https://par.nsf.gov/biblio/10547470. https://doi.org/10.31256/HSMR2024.31
Esser, Daniel S, Ertop, Tayfun Efe, McCabe, Emily, Maldonado, Fabien, Gillaspie, Erin A, Kuntz, Alan, and Webster_III, Robert J.
"A Continuum Lung Stapler Leveraging Phase Changing Metal for Dexterity and Stiffness". Country unknown/Code not available: The Hamlyn Symposium on Medical Robotics. https://doi.org/10.31256/HSMR2024.31.https://par.nsf.gov/biblio/10547470.
@article{osti_10547470,
place = {Country unknown/Code not available},
title = {A Continuum Lung Stapler Leveraging Phase Changing Metal for Dexterity and Stiffness},
url = {https://par.nsf.gov/biblio/10547470},
DOI = {10.31256/HSMR2024.31},
abstractNote = {Lung cancer claims over 130,000 lives per year in the USA. For those with malignant tumors requiring resection, minimally invasive thoracic surgery via a video assisted or robotic approach is an alternative to highly invasive open thoracotomy (in which the chest is “cracked” open). This involves the insertion of 3-5 ports through the chest wall and the use of a camera and instruments mounted to rigid shafts, which are used to resect tissue in a deflated lung. One of these tools is typically a stapler which is able to simultaneously cut and seal the lung tissue. Tendon-driven continuum robots (TDCRs) are capable of curvilinear motions, which can add useful dexterity in constrained anatomical regions like the chest. However, the inherent flexibility of TDCRs presents challenges for integrating stapler-type end effectors. Lung staplers today are typically rigid tools because they require large axial forces to be transmitted along the tool shaft to fire staples. Such forces would apply large loads to curved continuum devices, changing their shapes and moving the end effector undesirably during staple firing. Low melting point alloys (LMPA) have been explored to stiffen substantially soft robots and compliant surgical devices. Here, we propose their use in a TDCR stapler to stiffen the tool shaft before staples are fired. Prior to stiffening, tendon actuation can provide enhanced maneuverability by curving the backbone compared to rigid staplers to position the stapler at the desired location.},
journal = {},
publisher = {The Hamlyn Symposium on Medical Robotics},
author = {Esser, Daniel S and Ertop, Tayfun Efe and McCabe, Emily and Maldonado, Fabien and Gillaspie, Erin A and Kuntz, Alan and Webster_III, Robert J},
}
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