
Publications
2021 |
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![]() | Xu, Yunti; Peyron, Quentin; Kim, Jongwoo; Burgner-Kahrs, Jessica Design of Lightweight and Extensible Tendon-Driven Continuum Robots using Origami Patterns Inproceedings 4th IEEE International Conference on Soft Robotics (RoboSoft) Accepted, 2021. BibTeX | Tags: continuum robot, design, extensible, follow-the-leader, origami, tendon-driven continuum robots @inproceedings{Xu2021, title = {Design of Lightweight and Extensible Tendon-Driven Continuum Robots using Origami Patterns}, author = {Yunti Xu and Quentin Peyron and Jongwoo Kim and Jessica Burgner-Kahrs}, year = {2021}, date = {2021-04-12}, booktitle = {4th IEEE International Conference on Soft Robotics (RoboSoft) Accepted}, keywords = {continuum robot, design, extensible, follow-the-leader, origami, tendon-driven continuum robots}, pubstate = {published}, tppubtype = {inproceedings} } |
![]() | Modes, Vincent; Ortmaier, Tobias; Burgner-Kahrs, Jessica Shape Sensing Based on Longitudinal Strain Measurements Considering Elongation, Bending and Twisting Journal Article IEEE Sensors Journal, 21 (5), pp. 6712-6723, 2021. Abstract | Links | BibTeX | Tags: continuum robot, modeling, shape sensing @article{Modes2020b, title = {Shape Sensing Based on Longitudinal Strain Measurements Considering Elongation, Bending and Twisting}, author = {Vincent Modes and Tobias Ortmaier and Jessica Burgner-Kahrs }, doi = {10.1109/JSEN.2020.3043999}, year = {2021}, date = {2021-03-01}, journal = {IEEE Sensors Journal}, volume = {21}, number = {5}, pages = {6712-6723}, abstract = {The inherent flexibility, the small dimensions as well as the curvilinear shape of continuum robots makes it challenging to precisely measure their shape. Optical fibers with Bragg gratings (FBGs) provide a powerful tool to reconstruct the centerline of continuum robots. We present a theoretical model to determine the shape of such a sensor array based on longitudinal strain measurements and incorporating bending, twisting, and elongation. To validate our approach, we conduct several simulations by calculating arbitrary shapes based on the Cosserat rod theory. Our algorithm showed a maximum mean relative shape deviation of 0.04%, although the sensor array was twisted up to 78 degrees. Because we derive a closed-form solution for the strain curvature twist model, we also give analytical sensitivity values for the model, which can be used in the calculation of error propagation.}, keywords = {continuum robot, modeling, shape sensing}, pubstate = {published}, tppubtype = {article} } The inherent flexibility, the small dimensions as well as the curvilinear shape of continuum robots makes it challenging to precisely measure their shape. Optical fibers with Bragg gratings (FBGs) provide a powerful tool to reconstruct the centerline of continuum robots. We present a theoretical model to determine the shape of such a sensor array based on longitudinal strain measurements and incorporating bending, twisting, and elongation. To validate our approach, we conduct several simulations by calculating arbitrary shapes based on the Cosserat rod theory. Our algorithm showed a maximum mean relative shape deviation of 0.04%, although the sensor array was twisted up to 78 degrees. Because we derive a closed-form solution for the strain curvature twist model, we also give analytical sensitivity values for the model, which can be used in the calculation of error propagation. |
![]() | Böttcher, Georg; Lilge, Sven; Burgner-Kahrs, Jessica Design of a Reconfigurable Parallel Continuum Robot with Tendon-Actuated Kinematic Chains Journal Article IEEE Robotics and Automation Letters, 2021. Abstract | Links | BibTeX | Tags: collaborating continuum robots, design, parallel continuum robot, tendon-driven continuum robots @article{Boettcher2021, title = {Design of a Reconfigurable Parallel Continuum Robot with Tendon-Actuated Kinematic Chains}, author = {Georg Böttcher and Sven Lilge and Jessica Burgner-Kahrs}, doi = {10.1109/LRA.2021.3057557}, year = {2021}, date = {2021-02-05}, journal = {IEEE Robotics and Automation Letters}, abstract = {In this work, a novel spatial parallel continuum robot is proposed. It is composed of three tendon-actuated continuum robots as kinematic chains that are coupled at a common end-effector platform by spherical joints. A modular design approach is used, allowing the reconfiguration of each continuum robot's base position and orientation to adapt the overall structure to application specific constraints and environments. The parallel continuum robot is evaluated in terms of its position and orientation repeatability. Furthermore, comparisons are made to the performance of the single continuum kinematic chains. Overall, average position and orientation repeatabilities of 3.3 mm and 1.2 can be achieved for the parallel continuum robot, with a single individual continuum segment showing repeatabilities of 5.5 mm and 3.2. The proposed parallel continuum robot exhibits improved repeatabilities than each of the employed individual continuum segments, improving the average repeatability by 67% for position and 167% for orientation, respectively.}, keywords = {collaborating continuum robots, design, parallel continuum robot, tendon-driven continuum robots}, pubstate = {published}, tppubtype = {article} } In this work, a novel spatial parallel continuum robot is proposed. It is composed of three tendon-actuated continuum robots as kinematic chains that are coupled at a common end-effector platform by spherical joints. A modular design approach is used, allowing the reconfiguration of each continuum robot's base position and orientation to adapt the overall structure to application specific constraints and environments. The parallel continuum robot is evaluated in terms of its position and orientation repeatability. Furthermore, comparisons are made to the performance of the single continuum kinematic chains. Overall, average position and orientation repeatabilities of 3.3 mm and 1.2 can be achieved for the parallel continuum robot, with a single individual continuum segment showing repeatabilities of 5.5 mm and 3.2. The proposed parallel continuum robot exhibits improved repeatabilities than each of the employed individual continuum segments, improving the average repeatability by 67% for position and 167% for orientation, respectively. |
![]() | Rao, Priyanka; Peyron, Quentin; Lilge, Sven; Burgner-Kahrs, Jessica How to Model Tendon-Driven Continuum Robots and Benchmark Modelling Performance Journal Article Frontiers in Robotics and AI, 7 (630245), pp. 20, 2021. Abstract | Links | BibTeX | Tags: continuum robot, modeling, tendon actuated, tendon-driven continuum robots @article{Rao2021, title = {How to Model Tendon-Driven Continuum Robots and Benchmark Modelling Performance}, author = {Priyanka Rao and Quentin Peyron and Sven Lilge and Jessica Burgner-Kahrs}, doi = {10.3389/frobt.2020.630245}, year = {2021}, date = {2021-02-02}, journal = {Frontiers in Robotics and AI}, volume = {7}, number = {630245}, pages = {20}, abstract = {Tendon actuation is one of the most prominent actuation principles for continuum robots. To date, a wide variety of modelling approaches has been derived to describe the deformations of tendon-driven continuum robots. Motivated by the need for a comprehensive overview of existing methodologies, this work summarizes and outlines state-of-the-art modelling approaches. In particular, the most relevant models are classified based on backbone representations and kinematic as well as static assumptions. Numerical case studies are conducted to compare the performance of representative modelling approaches from the current state-of-the-art, considering varying robot parameters and scenarios. The approaches show different performances in terms of accuracy and computation time. Guidelines for the selection of the most suitable approach for given designs of tendon-driven continuum robots and applications are deduced from these results.}, keywords = {continuum robot, modeling, tendon actuated, tendon-driven continuum robots}, pubstate = {published}, tppubtype = {article} } Tendon actuation is one of the most prominent actuation principles for continuum robots. To date, a wide variety of modelling approaches has been derived to describe the deformations of tendon-driven continuum robots. Motivated by the need for a comprehensive overview of existing methodologies, this work summarizes and outlines state-of-the-art modelling approaches. In particular, the most relevant models are classified based on backbone representations and kinematic as well as static assumptions. Numerical case studies are conducted to compare the performance of representative modelling approaches from the current state-of-the-art, considering varying robot parameters and scenarios. The approaches show different performances in terms of accuracy and computation time. Guidelines for the selection of the most suitable approach for given designs of tendon-driven continuum robots and applications are deduced from these results. |
2020 |
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![]() | Lilge, Sven; Nuelle, Kathrin; Böttcher, Georg; Spindeldreier, Svenja; Burgner-Kahrs, Jessica Tendon Actuated Continuous Structures in Planar Parallel Robots: A Kinematic Analysis Journal Article ASME Journal of Mechanisms and Robotics, 13 (1), pp. 011025 (11 pages), 2020. Abstract | Links | BibTeX | Tags: design, modeling, parallel continuum robot, tendon actuated, tendon-driven continuum robots @article{Lilge2020, title = {Tendon Actuated Continuous Structures in Planar Parallel Robots: A Kinematic Analysis}, author = {Sven Lilge and Kathrin Nuelle and Georg Böttcher and Svenja Spindeldreier and Jessica Burgner-Kahrs}, doi = {10.1115/1.4049058}, year = {2020}, date = {2020-11-07}, journal = {ASME Journal of Mechanisms and Robotics}, volume = {13}, number = {1}, pages = {011025 (11 pages)}, abstract = {The use of continuous and flexible structures instead of rigid links and discrete joints is a growing field of robotics research. Recent work focuses on the inclusion of continuous segments in parallel robots to benefit from their structural advantages, such as a high dexterity and compliance. While some applications and designs of these novel parallel continuum robots have been presented, the field remains largely unexplored. Furthermore, an exact quantification of the kinematic advantages and disadvantages when using continuous structures in parallel robots is yet to be performed. In this paper, planar parallel robot designs using tendon actuated continuum robots instead of rigid links and discrete joints are proposed. Using the well known 3-RRR manipulator as a reference design, two parallel continuum robots are derived. Inverse and differential kinematics of these designs are modeled using constant curvature assumptions, which can be adapted for other actuation mechanisms than tendons. Their kinematic performances are compared to the conventional parallel robot counterpart. On the basis of this comparison, the advantages and disadvantages of using continuous structures in parallel robots are quantified and analyzed. Results show that parallel continuum robot can be kinematic equivalent and exhibit similar kinematic performances in comparison to conventional parallel robots depending on the chosen design.}, keywords = {design, modeling, parallel continuum robot, tendon actuated, tendon-driven continuum robots}, pubstate = {published}, tppubtype = {article} } The use of continuous and flexible structures instead of rigid links and discrete joints is a growing field of robotics research. Recent work focuses on the inclusion of continuous segments in parallel robots to benefit from their structural advantages, such as a high dexterity and compliance. While some applications and designs of these novel parallel continuum robots have been presented, the field remains largely unexplored. Furthermore, an exact quantification of the kinematic advantages and disadvantages when using continuous structures in parallel robots is yet to be performed. In this paper, planar parallel robot designs using tendon actuated continuum robots instead of rigid links and discrete joints are proposed. Using the well known 3-RRR manipulator as a reference design, two parallel continuum robots are derived. Inverse and differential kinematics of these designs are modeled using constant curvature assumptions, which can be adapted for other actuation mechanisms than tendons. Their kinematic performances are compared to the conventional parallel robot counterpart. On the basis of this comparison, the advantages and disadvantages of using continuous structures in parallel robots are quantified and analyzed. Results show that parallel continuum robot can be kinematic equivalent and exhibit similar kinematic performances in comparison to conventional parallel robots depending on the chosen design. |
![]() | Donat, Heiko; Lilge, Sven; Burgner-Kahrs, Jessica; Steil, Jochen J Estimating Tip Contact Forces for Concentric Tube Continuum Robots based on Backbone Deflection Journal Article IEEE Transactions on Medical Robotics and Bionics , 2 (4), pp. 619-630, 2020. Abstract | Links | BibTeX | Tags: concentric tube continuum robot, machine learning, sensing @article{Donat2020, title = {Estimating Tip Contact Forces for Concentric Tube Continuum Robots based on Backbone Deflection}, author = {Heiko Donat and Sven Lilge and Jessica Burgner-Kahrs and Jochen J. Steil}, doi = {10.1109/TMRB.2020.3034258}, year = {2020}, date = {2020-10-29}, journal = {IEEE Transactions on Medical Robotics and Bionics }, volume = {2}, number = {4}, pages = {619-630}, abstract = {Concentric Tube Continuum Robots are among the smallest and most flexible instruments in development for minimally invasive surgery, thereby enabling operations in areas within the human body that are difficult to reach. Unfortunately, integrating state-of-the-art force sensors is challenging for these robots due to their small form factor, although contact forces are essential information in surgical procedures. In this work, we propose a novel data-driven approach based on Deep Direct Cascade Learning (DDCL) to create a virtual sensor for computing the tip contact force of Concentric Tube Continuum Robots. By exploiting the robot’s backbone’s inherent elasticity, deflection is used to estimate the respective external tip contact force. We evaluate our approach on different data representations for a single tube and apply it subsequently on a three-segment Concentric Tube Continuum Robot. Furthermore, we devise a novel transfer learning approach through DDCL to improve the estimation accuracy by pre-training a cascaded network with simulated data. Subsequently, we fine-tune the network based on a small real-world data set recorded from the physical robot.}, keywords = {concentric tube continuum robot, machine learning, sensing}, pubstate = {published}, tppubtype = {article} } Concentric Tube Continuum Robots are among the smallest and most flexible instruments in development for minimally invasive surgery, thereby enabling operations in areas within the human body that are difficult to reach. Unfortunately, integrating state-of-the-art force sensors is challenging for these robots due to their small form factor, although contact forces are essential information in surgical procedures. In this work, we propose a novel data-driven approach based on Deep Direct Cascade Learning (DDCL) to create a virtual sensor for computing the tip contact force of Concentric Tube Continuum Robots. By exploiting the robot’s backbone’s inherent elasticity, deflection is used to estimate the respective external tip contact force. We evaluate our approach on different data representations for a single tube and apply it subsequently on a three-segment Concentric Tube Continuum Robot. Furthermore, we devise a novel transfer learning approach through DDCL to improve the estimation accuracy by pre-training a cascaded network with simulated data. Subsequently, we fine-tune the network based on a small real-world data set recorded from the physical robot. |
![]() | Nuelle, Kathrin; Sterneck, Tim; Lilge, Sven; Xiong, Dhezu; Burgner-Kahrs, Jessica; Ortmaier, Tobias Modeling, Calibration, and Evaluation of a Planar Parallel Continuum Robot based on Tendon Actuation Journal Article IEEE Robotics & Automation Letter, 5 (4), pp. 5811 - 5818, 2020. Abstract | Links | BibTeX | Tags: calibration, control, design, modeling, parallel continuum robot, tendon actuated, tendon-driven continuum robots @article{Nuelle2020, title = {Modeling, Calibration, and Evaluation of a Planar Parallel Continuum Robot based on Tendon Actuation}, author = {Kathrin Nuelle and Tim Sterneck and Sven Lilge and Dhezu Xiong and Jessica Burgner-Kahrs and Tobias Ortmaier}, doi = {10.1109/LRA.2020.3010213}, year = {2020}, date = {2020-07-17}, journal = {IEEE Robotics & Automation Letter}, volume = {5}, number = {4}, pages = {5811 - 5818}, abstract = {In this work, a novel planar parallel continuum robot (PCR) is introduced, consisting of three kinematic chains that are coupled at a triangular end-effector platform and include tendon-actuated continuum segments. The kinematics of the resulting structure are derived by adapting the descriptions for conventional planar parallel manipulators to include constant curvature bending of the utilized continuous segments. To account for friction and non-linear material effects, a data-driven model is used to relate tendon displacements and curvature of the utilized continuum segments. A calibration of the derived kinematic model is conducted to specifically represent the constructed prototype. This includes the calibration of geometric parameters for each kinematic chain and for the end-effector platform. During evaluation, positioning repeatability of 1.0% in relation to one continuum segment length of the robot, and positioning accuracy of 1.4%, are achieved. These results are comparable to commonly used kineto-static modeling approaches for PCR. The presented model achieves high path accuracies regarding the robot's end-effector pose in an open-loop control scenario.}, keywords = {calibration, control, design, modeling, parallel continuum robot, tendon actuated, tendon-driven continuum robots}, pubstate = {published}, tppubtype = {article} } In this work, a novel planar parallel continuum robot (PCR) is introduced, consisting of three kinematic chains that are coupled at a triangular end-effector platform and include tendon-actuated continuum segments. The kinematics of the resulting structure are derived by adapting the descriptions for conventional planar parallel manipulators to include constant curvature bending of the utilized continuous segments. To account for friction and non-linear material effects, a data-driven model is used to relate tendon displacements and curvature of the utilized continuum segments. A calibration of the derived kinematic model is conducted to specifically represent the constructed prototype. This includes the calibration of geometric parameters for each kinematic chain and for the end-effector platform. During evaluation, positioning repeatability of 1.0% in relation to one continuum segment length of the robot, and positioning accuracy of 1.4%, are achieved. These results are comparable to commonly used kineto-static modeling approaches for PCR. The presented model achieves high path accuracies regarding the robot's end-effector pose in an open-loop control scenario. |
![]() | Grassmann, Reinhard; Lilge, Sven; Le, Phuong; Burgner-Kahrs, Jessica CTCR Prototype Development: An Obstacle in the Research Community? Inproceedings RSS 2020 Workshop RobRetro, 2020. Links | BibTeX | Tags: concentric tube continuum robot, retrospective @inproceedings{Grassmann2020, title = {CTCR Prototype Development: An Obstacle in the Research Community?}, author = {Reinhard Grassmann and Sven Lilge and Phuong Le and Jessica Burgner-Kahrs}, url = {https://openreview.net/forum?id=bYLFxFQPFtX}, year = {2020}, date = {2020-05-31}, booktitle = {RSS 2020 Workshop RobRetro}, keywords = {concentric tube continuum robot, retrospective}, pubstate = {published}, tppubtype = {inproceedings} } |
![]() | Modes, Vincent; Burgner-Kahrs, Jessica Calibration of Concentric Tube Continuum Robots: Automatic Alignment of Precurved Elastic Tubes Journal Article IEEE Robotics and Automation Letters, 5 (1), pp. 103–110, 2020. Links | BibTeX | Tags: Accuracy, calibration, concentric tube continuum robot, continuum robot @article{Modes2020, title = {Calibration of Concentric Tube Continuum Robots: Automatic Alignment of Precurved Elastic Tubes}, author = {Vincent Modes and Jessica Burgner-Kahrs}, doi = {10.1109/LRA.2019.2946060}, year = {2020}, date = {2020-01-01}, journal = {IEEE Robotics and Automation Letters}, volume = {5}, number = {1}, pages = {103--110}, keywords = {Accuracy, calibration, concentric tube continuum robot, continuum robot}, pubstate = {published}, tppubtype = {article} } |
2019 |
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![]() | Amanov, E; Nguyen, T -D; Burgner-Kahrs, J Tendon-driven Continuum Robots with Extensible Sections - A Model-based Evaluation of Path Following Motions Journal Article International Journal of Robotics Research, Online First , 2019. Abstract | Links | BibTeX | Tags: Accuracy, continuum robot, design, extensible, follow-the-leader, tendon actuated, tendon-driven continuum robots @article{Amanov2019, title = {Tendon-driven Continuum Robots with Extensible Sections - A Model-based Evaluation of Path Following Motions}, author = {E Amanov and T -D Nguyen and J Burgner-Kahrs}, doi = {10.1177/0278364919886047}, year = {2019}, date = {2019-11-17}, journal = {International Journal of Robotics Research}, volume = {Online First}, abstract = {Continuum robots are highly miniaturizable, exhibit non-linear shapes with several curves, and are flexible and compliant. In particular, concentric-tube and tendon-driven continuum robots can be designed on a small scale with diameters of below 10 mm. A small diameter-to-length ratio enables insertion of these robots through small entry points in order to reach hardly accessible regions by avoiding obstacles. This scenario can often be found in minimally invasive surgery and technical inspections. However, to reach the target region, a deployment along a narrow tortuous path is often required. Common tendon-driven continuum robots are intrinsically incapable of such deployment and concentric-tube continuum robots require special path conditions and intensive parameter optimization. Other proposed robot types, such as hyper-redundant and pneumatically actuated robots, exhibit less favorable diameter-to-length ratios and are thus not suitable for those tasks. Since the limiting factors are found in the design of continuum robots, we propose a novel tendon-driven continuum robot design, which features an additional degree of freedom in each robot section. The backbone is composed of straight, concentrically arranged tubes, each of which composes a section and is used to adapt its length. We present a three-section continuum robot prototype with a diameter of 7 mm, determine its follow-the-leader capabilities theoretically, and validate the results experimentally using model-based control. For our 165 mm long robot prototype, the repeatability is below 2.38 mm. The model accuracy reaches a median of 3.16% over 25 configurations with respect to robot length. The path-following error over five curvilinear paths results in median errors of 2.59% with respect to robot length.}, keywords = {Accuracy, continuum robot, design, extensible, follow-the-leader, tendon actuated, tendon-driven continuum robots}, pubstate = {published}, tppubtype = {article} } Continuum robots are highly miniaturizable, exhibit non-linear shapes with several curves, and are flexible and compliant. In particular, concentric-tube and tendon-driven continuum robots can be designed on a small scale with diameters of below 10 mm. A small diameter-to-length ratio enables insertion of these robots through small entry points in order to reach hardly accessible regions by avoiding obstacles. This scenario can often be found in minimally invasive surgery and technical inspections. However, to reach the target region, a deployment along a narrow tortuous path is often required. Common tendon-driven continuum robots are intrinsically incapable of such deployment and concentric-tube continuum robots require special path conditions and intensive parameter optimization. Other proposed robot types, such as hyper-redundant and pneumatically actuated robots, exhibit less favorable diameter-to-length ratios and are thus not suitable for those tasks. Since the limiting factors are found in the design of continuum robots, we propose a novel tendon-driven continuum robot design, which features an additional degree of freedom in each robot section. The backbone is composed of straight, concentrically arranged tubes, each of which composes a section and is used to adapt its length. We present a three-section continuum robot prototype with a diameter of 7 mm, determine its follow-the-leader capabilities theoretically, and validate the results experimentally using model-based control. For our 165 mm long robot prototype, the repeatability is below 2.38 mm. The model accuracy reaches a median of 3.16% over 25 configurations with respect to robot length. The path-following error over five curvilinear paths results in median errors of 2.59% with respect to robot length. |
![]() | Amanov, Ernar Designing a robotic port system for laparo-endoscopic single-site surgery PhD Thesis Leibniz University Hannover, 2019. Abstract | Links | BibTeX | Tags: continuum robot, design, medical robotics, minimally-invasive surgery, soft robot, stiffening, tendon actuated, tendon-driven continuum robots @phdthesis{Amanov2019b, title = {Designing a robotic port system for laparo-endoscopic single-site surgery}, author = {Ernar Amanov }, url = {https://www.repo.uni-hannover.de/handle/123456789/10149}, doi = {10.15488/10087}, year = {2019}, date = {2019-10-14}, school = {Leibniz University Hannover}, abstract = {Current research and development in the field of surgical interventions aim to reduce the invasiveness by using few incisions or natural orifices in the body to access the surgical site. Considering surgeries in the abdominal cavity, the Laparo-Endoscopic Single-site Surgery (LESS) can be performed through a single incision in the navel, reducing blood loss, post-operative trauma, and improving the cosmetic outcome. However, LESS results in less intuitive instrument control, impaired ergonomic, loss of depth and haptic perception, and restriction of instrument positioning by a single incision. Robot-assisted surgery addresses these shortcomings, by introducing highly articulated, flexible robotic instruments, ergonomic control consoles with 3D visualization, and intuitive instrument control algorithms. The flexible robotic instruments are usually introduced into the abdomen via a rigid straight port, such that the positioning of the tools and therefore the accessibility of anatomical structures is still constrained by the incision location. To address this limitation, articulated ports for LESS are proposed by recent research works. However, they focus on only a few aspects, which are relevant to the surgery, such that a design considering all requirements for LESS has not been proposed yet. This partially originates in the lack of anatomical data of specific applications. Further, no general design guidelines exist and only a few evaluation metrics are proposed. To target these challenges, this thesis focuses on the design of an articulated robotic port for LESS partial nephrectomy. A novel approach is introduced, acquiring the available abdominal workspace, integrated into the surgical workflow. Based on several generated patient datasets and developed metrics, design parameter optimization is conducted. Analyzing the surgical procedure, a comprehensive requirement list is established and applied to design a robotic system, proposing a tendon-driven continuum robot as the articulated port structure. Especially, the aspects of stiffening and sterile design are addressed. In various experimental evaluations, the reachability, the stiffness, and the overall design are evaluated. The findings identify layer jamming as the superior stiffening method. Further, the articulated port is proven to enhance the accessibility of anatomical structures and offer a patient and incision location independent design.}, keywords = {continuum robot, design, medical robotics, minimally-invasive surgery, soft robot, stiffening, tendon actuated, tendon-driven continuum robots}, pubstate = {published}, tppubtype = {phdthesis} } Current research and development in the field of surgical interventions aim to reduce the invasiveness by using few incisions or natural orifices in the body to access the surgical site. Considering surgeries in the abdominal cavity, the Laparo-Endoscopic Single-site Surgery (LESS) can be performed through a single incision in the navel, reducing blood loss, post-operative trauma, and improving the cosmetic outcome. However, LESS results in less intuitive instrument control, impaired ergonomic, loss of depth and haptic perception, and restriction of instrument positioning by a single incision. Robot-assisted surgery addresses these shortcomings, by introducing highly articulated, flexible robotic instruments, ergonomic control consoles with 3D visualization, and intuitive instrument control algorithms. The flexible robotic instruments are usually introduced into the abdomen via a rigid straight port, such that the positioning of the tools and therefore the accessibility of anatomical structures is still constrained by the incision location. To address this limitation, articulated ports for LESS are proposed by recent research works. However, they focus on only a few aspects, which are relevant to the surgery, such that a design considering all requirements for LESS has not been proposed yet. This partially originates in the lack of anatomical data of specific applications. Further, no general design guidelines exist and only a few evaluation metrics are proposed. To target these challenges, this thesis focuses on the design of an articulated robotic port for LESS partial nephrectomy. A novel approach is introduced, acquiring the available abdominal workspace, integrated into the surgical workflow. Based on several generated patient datasets and developed metrics, design parameter optimization is conducted. Analyzing the surgical procedure, a comprehensive requirement list is established and applied to design a robotic system, proposing a tendon-driven continuum robot as the articulated port structure. Especially, the aspects of stiffening and sterile design are addressed. In various experimental evaluations, the reachability, the stiffness, and the overall design are evaluated. The findings identify layer jamming as the superior stiffening method. Further, the articulated port is proven to enhance the accessibility of anatomical structures and offer a patient and incision location independent design. |
![]() | Granna, Josephine Leibniz University Hannover, 2019. Abstract | Links | BibTeX | Tags: computational design, concentric tube continuum robot, minimally-invasive surgery, trajectory planning @phdthesis{Granna2020, title = {Multi-Objective Particle Swarm Optimization for the Structural Design of Concentric Tube Continuum Robots for Medical Applications}, author = {Josephine Granna}, url = {https://www.repo.uni-hannover.de/handle/123456789/9241}, doi = {10.15488/9188}, year = {2019}, date = {2019-10-14}, school = {Leibniz University Hannover}, abstract = {Concentric tube robots belong to the class of continuum robotic systems whose morphology is described by continuous tangent curvature vectors. They are composed of multiple, interacting tubes nested inside one another and are characterized by their inherent flexibility. Concentric tube continuum robots equipped with tools at their distal end have high potential in minimally invasive surgery. Their morphology enables them to reach sites within the body that are inaccessible with commercial tools or that require large incisions. Further, they can be deployed through a tight lumen or follow a nonlinear path. Fundamental research has been the focus during the last years bringing them closer to the operating room. However, there remain challenges that require attention. The structural synthesis of concentric tube continuum robots is one of these challenges, as these types of robots are characterized by their large parameter space. On the one hand, this is advantageous, as they can be deployed in different patients, anatomies, or medical applications. On the other hand, the composition of the tubes and their design is not a straightforward task but one that requires intensive knowledge of anatomy and structural behavior. Prior to the utilization of such robots, the composition of tubes (i.e. the selection of design parameters and application-specific constraints) must be solved to determine a robotic design that is specifically targeted towards an application or patient. Kinematic models that describe the change in morphology and complex motion increase the complexity of this synthesis, as their mathematical description is highly nonlinear. Thus, the state of the art is concerned with the structural design of these types of robots and proposes optimization algorithms to solve for a composition of tubes for a specific patient case or application. However, existing approaches do not consider the overall parameter space, cannot handle the nonlinearity of the model, or multiple objectives that describe most medical applications and tasks. This work aims to solve these fundamental challenges by solving the parameter optimization problem by utilizing a multi-objective optimization algorithm. The main concern of this thesis is the general methodology to solve for patient- and application-specific design of concentric tube continuum robots and presents key parameters, objectives, and constraints. The proposed optimization method is based on evolutionary concepts that can handle multiple objectives, where the set of parameters is represented by a decision vector that can be of variable dimension in multidimensional space. Global optimization algorithms specifically target the constrained search space of concentric tube continuum robots and nonlinear optimization enables to handle the highly nonlinear elasticity modeling. The proposed methodology is then evaluated based on three examples that include cooperative task deployment of two robotic arms, structural stiffness optimization under the consideration of workspace constraints and external forces, and laser-induced thermal therapy in the brain using a concentric tube continuum robot. In summary, the main contributions are 1) the development of an optimization methodology that describes the key parameters, objectives, and constraints of the parameter optimization problem of concentric tube continuum robots, 2) the selection of an appropriate optimization algorithm that can handle the multidimensional search space and diversity of the optimization problem with multiple objectives, and 3) the evaluation of the proposed optimization methodology and structural synthesis based on three real applications.}, keywords = {computational design, concentric tube continuum robot, minimally-invasive surgery, trajectory planning}, pubstate = {published}, tppubtype = {phdthesis} } Concentric tube robots belong to the class of continuum robotic systems whose morphology is described by continuous tangent curvature vectors. They are composed of multiple, interacting tubes nested inside one another and are characterized by their inherent flexibility. Concentric tube continuum robots equipped with tools at their distal end have high potential in minimally invasive surgery. Their morphology enables them to reach sites within the body that are inaccessible with commercial tools or that require large incisions. Further, they can be deployed through a tight lumen or follow a nonlinear path. Fundamental research has been the focus during the last years bringing them closer to the operating room. However, there remain challenges that require attention. The structural synthesis of concentric tube continuum robots is one of these challenges, as these types of robots are characterized by their large parameter space. On the one hand, this is advantageous, as they can be deployed in different patients, anatomies, or medical applications. On the other hand, the composition of the tubes and their design is not a straightforward task but one that requires intensive knowledge of anatomy and structural behavior. Prior to the utilization of such robots, the composition of tubes (i.e. the selection of design parameters and application-specific constraints) must be solved to determine a robotic design that is specifically targeted towards an application or patient. Kinematic models that describe the change in morphology and complex motion increase the complexity of this synthesis, as their mathematical description is highly nonlinear. Thus, the state of the art is concerned with the structural design of these types of robots and proposes optimization algorithms to solve for a composition of tubes for a specific patient case or application. However, existing approaches do not consider the overall parameter space, cannot handle the nonlinearity of the model, or multiple objectives that describe most medical applications and tasks. This work aims to solve these fundamental challenges by solving the parameter optimization problem by utilizing a multi-objective optimization algorithm. The main concern of this thesis is the general methodology to solve for patient- and application-specific design of concentric tube continuum robots and presents key parameters, objectives, and constraints. The proposed optimization method is based on evolutionary concepts that can handle multiple objectives, where the set of parameters is represented by a decision vector that can be of variable dimension in multidimensional space. Global optimization algorithms specifically target the constrained search space of concentric tube continuum robots and nonlinear optimization enables to handle the highly nonlinear elasticity modeling. The proposed methodology is then evaluated based on three examples that include cooperative task deployment of two robotic arms, structural stiffness optimization under the consideration of workspace constraints and external forces, and laser-induced thermal therapy in the brain using a concentric tube continuum robot. In summary, the main contributions are 1) the development of an optimization methodology that describes the key parameters, objectives, and constraints of the parameter optimization problem of concentric tube continuum robots, 2) the selection of an appropriate optimization algorithm that can handle the multidimensional search space and diversity of the optimization problem with multiple objectives, and 3) the evaluation of the proposed optimization methodology and structural synthesis based on three real applications. |
![]() | Grassmann, Reinhard; Burgner-Kahrs, Jessica Smooth Orientation Trajectory Generator Respecting Kinematic Limits Inproceedings IEEE-RAS International Conference on Humanoid Robots, 2019. BibTeX | Tags: continuum robot, quaternion, Robotics, trajectory planning @inproceedings{Grassmann2019b, title = {Smooth Orientation Trajectory Generator Respecting Kinematic Limits}, author = {Reinhard Grassmann and Jessica Burgner-Kahrs}, year = {2019}, date = {2019-10-01}, booktitle = {IEEE-RAS International Conference on Humanoid Robots}, keywords = {continuum robot, quaternion, Robotics, trajectory planning}, pubstate = {published}, tppubtype = {inproceedings} } |
![]() | Grassmann, Reinhard M; Burgner-Kahrs, Jessica Quaternion-Based Smooth Trajectory Generator for Via Poses in SE(3) Considering Kinematic Limits in Cartesian Space Journal Article IEEE Robotics and Automation Letters, 4 (4), pp. 4192–4199, 2019. Links | BibTeX | Tags: continuum robot, quaternion, Robotics @article{Grassmann2019d, title = {Quaternion-Based Smooth Trajectory Generator for Via Poses in SE(3) Considering Kinematic Limits in Cartesian Space}, author = {Reinhard M Grassmann and Jessica Burgner-Kahrs}, doi = {10.1109/LRA.2019.2931133}, year = {2019}, date = {2019-07-25}, journal = {IEEE Robotics and Automation Letters}, volume = {4}, number = {4}, pages = {4192--4199}, keywords = {continuum robot, quaternion, Robotics}, pubstate = {published}, tppubtype = {article} } |
![]() | Grassmann, Reinhard; Burgner-Kahrs, Jessica On the Merits of Joint Space and Orientation Representations in Learning the Forward Kinematics in SE(3) Inproceedings Robotics: Science and Systems Conference, 10 pages, 2019. Links | BibTeX | Tags: concentric tube continuum robot, continuum robot, machine learning, Robotics @inproceedings{Grassmann2019a, title = {On the Merits of Joint Space and Orientation Representations in Learning the Forward Kinematics in SE(3)}, author = {Reinhard Grassmann and Jessica Burgner-Kahrs}, url = {http://www.roboticsproceedings.org/rss15/p17.pdf}, year = {2019}, date = {2019-07-01}, booktitle = {Robotics: Science and Systems Conference, 10 pages}, keywords = {concentric tube continuum robot, continuum robot, machine learning, Robotics}, pubstate = {published}, tppubtype = {inproceedings} } |
![]() | Donat, Heiko; Lilge, Sven; Steil, Jochen; Burgner-Kahrs, Jessica Towards Learning Force Sensing for a Concentric Tube Continuum Robot Inproceedings Workshop on Open Challenges and State-of-the-Art in Control System Design and Technology Development for Surgical Robotic Systems, IEEE International Conference on Robotics and Automation, 2019. BibTeX | Tags: concentric tube continuum robot, machine learning @inproceedings{Donat2019, title = {Towards Learning Force Sensing for a Concentric Tube Continuum Robot}, author = {Heiko Donat and Sven Lilge and Jochen Steil and Jessica Burgner-Kahrs}, year = {2019}, date = {2019-05-20}, booktitle = {Workshop on Open Challenges and State-of-the-Art in Control System Design and Technology Development for Surgical Robotic Systems, IEEE International Conference on Robotics and Automation}, keywords = {concentric tube continuum robot, machine learning}, pubstate = {published}, tppubtype = {inproceedings} } |
![]() | Grassmann, Reinhard M; Burgner-Kahrs, Jessica Adjustment Device for Joint Level Calibration of Continuum Robots Inproceedings Workshop on Opportunities and Challenges of Soft Robotics across Different Length Scales, IEEE International Conference on Robotics and Automation, 2019. BibTeX | Tags: Accuracy, calibration, continuum robot @inproceedings{Grassmann2019c, title = {Adjustment Device for Joint Level Calibration of Continuum Robots}, author = {Reinhard M Grassmann and Jessica Burgner-Kahrs}, year = {2019}, date = {2019-05-20}, booktitle = {Workshop on Opportunities and Challenges of Soft Robotics across Different Length Scales, IEEE International Conference on Robotics and Automation}, keywords = {Accuracy, calibration, continuum robot}, pubstate = {published}, tppubtype = {inproceedings} } |
![]() | Lilge, Sven; Burgner-Kahrs, Jessica Controlling Concentric Tube Robots while Enforcing Shape Constraints Inproceedings Workshop on Open Challenges and State-of-the-Art in Control System Design and Technology Development for Surgical Robotic Systems, IEEE International Conference on Robotics and Automation, 2019. BibTeX | Tags: concentric tube continuum robot, shape constraint @inproceedings{Lilge2019, title = {Controlling Concentric Tube Robots while Enforcing Shape Constraints}, author = {Sven Lilge and Jessica Burgner-Kahrs}, year = {2019}, date = {2019-05-20}, booktitle = {Workshop on Open Challenges and State-of-the-Art in Control System Design and Technology Development for Surgical Robotic Systems, IEEE International Conference on Robotics and Automation}, keywords = {concentric tube continuum robot, shape constraint}, pubstate = {published}, tppubtype = {inproceedings} } |
![]() | Black, David; Lilge, Sven; Fellmann, Carolin; Reinschluessel, Anke V; Kreuer, Lars; Nabavi, Arya; Hahn, Horst K; Kikinis, Ron; Burgner-Kahrs, Jessica Auditory Display for Telerobotic Transnasal Surgery Using a Continuum Robot Journal Article Journal of Medical Robotics Research, 4 (2), pp. 1950004, 2019. Abstract | Links | BibTeX | Tags: concentric tube continuum robot, hri, teleoperation @article{Black2019, title = {Auditory Display for Telerobotic Transnasal Surgery Using a Continuum Robot}, author = {David Black and Sven Lilge and Carolin Fellmann and Anke V Reinschluessel and Lars Kreuer and Arya Nabavi and Horst K Hahn and Ron Kikinis and Jessica Burgner-Kahrs}, doi = {10.1142/S2424905X19500041}, year = {2019}, date = {2019-05-16}, journal = {Journal of Medical Robotics Research}, volume = {4}, number = {2}, pages = {1950004}, abstract = {Tubular continuum robots can follow complex curvilinear paths to reach restricted areas within the body. Using teleoperation, these robots can help minimize incisions and reduce trauma. However, drawbacks include the lack of haptic feedback and a limited view of the situs, often due to camera occlusion. This work presents novel auditory display to enhance interaction with such continuum robots to increase accuracy and path-following efficiency and reduce cognitive workload. We recreate a typical use case with a test environment that simulates a transnasal intervention through the sphenoidal sinus including a simulated continuum robot. Distance information is mapped to changes in a real-time audio synthesizer using sung voice to provide navigation cues. User studies with novice participants and clinicians were performed to evaluate the effects of auditory display on accuracy, task time, path following efficiency, subjective workload, and usability. When using auditory display, participants exhibit significant increase in accuracy, efficiency, and task time compared to visual-only display. Auditory display reduced subjective workload and raised usefulness and satisfaction ratings. The addition of auditory display for augmenting interaction with a teleoperated continuum robot has shown to benefit performance as well as usability. The method could benefit other scenarios in navigated surgery to increase accuracy and reduce workload.}, keywords = {concentric tube continuum robot, hri, teleoperation}, pubstate = {published}, tppubtype = {article} } Tubular continuum robots can follow complex curvilinear paths to reach restricted areas within the body. Using teleoperation, these robots can help minimize incisions and reduce trauma. However, drawbacks include the lack of haptic feedback and a limited view of the situs, often due to camera occlusion. This work presents novel auditory display to enhance interaction with such continuum robots to increase accuracy and path-following efficiency and reduce cognitive workload. We recreate a typical use case with a test environment that simulates a transnasal intervention through the sphenoidal sinus including a simulated continuum robot. Distance information is mapped to changes in a real-time audio synthesizer using sung voice to provide navigation cues. User studies with novice participants and clinicians were performed to evaluate the effects of auditory display on accuracy, task time, path following efficiency, subjective workload, and usability. When using auditory display, participants exhibit significant increase in accuracy, efficiency, and task time compared to visual-only display. Auditory display reduced subjective workload and raised usefulness and satisfaction ratings. The addition of auditory display for augmenting interaction with a teleoperated continuum robot has shown to benefit performance as well as usability. The method could benefit other scenarios in navigated surgery to increase accuracy and reduce workload. |
![]() | Granna, Josephine; Nabavi, Arya; Burgner-Kahrs, Jessica Computer-assisted planning for a concentric tube robotic system in neurosurgery Journal Article International Journal of Computer Assisted Radiology and Surgery, 14 (2), pp. 335–344, 2019. Abstract | Links | BibTeX | Tags: computational design, concentric tube continuum robot, minimally-invasive surgery, planning, Surgery @article{Granna2018, title = {Computer-assisted planning for a concentric tube robotic system in neurosurgery}, author = {Josephine Granna and Arya Nabavi and Jessica Burgner-Kahrs}, doi = {10.1007/s11548-018-1890-8}, year = {2019}, date = {2019-02-14}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {14}, number = {2}, pages = {335--344}, abstract = {Purpose: Laser-induced thermotherapy in the brain is a minimally invasive procedure to denature tumor tissue. However, irregularly shaped brain tumors cannot be treated using existing commercial systems. Thus, we present a new concept for laser-induced thermotherapy using a concentric tube robotic system. The planning procedure is complex and consists of the optimal distribution of thermal laser ablations within a volume as well as design and configuration parameter optimization of the concentric tube robot. Methods: We propose a novel computer-assisted planning procedure that decomposes the problem into task- and robot-specific planning and uses a multi-objective particle swarm optimization algorithm with variable length. Results: The algorithm determines a Pareto-front of optimal ablation distributions for three patient datasets. It considers multiple objectives and determines optimal robot parameters for multiple trajectories to access the tumor volume. Conclusions: We prove the effectiveness of our planning procedure to enable the treatment of irregularly shaped brain tumors. Multiple trajectories further increase the applicability of the procedure.}, keywords = {computational design, concentric tube continuum robot, minimally-invasive surgery, planning, Surgery}, pubstate = {published}, tppubtype = {article} } Purpose: Laser-induced thermotherapy in the brain is a minimally invasive procedure to denature tumor tissue. However, irregularly shaped brain tumors cannot be treated using existing commercial systems. Thus, we present a new concept for laser-induced thermotherapy using a concentric tube robotic system. The planning procedure is complex and consists of the optimal distribution of thermal laser ablations within a volume as well as design and configuration parameter optimization of the concentric tube robot. Methods: We propose a novel computer-assisted planning procedure that decomposes the problem into task- and robot-specific planning and uses a multi-objective particle swarm optimization algorithm with variable length. Results: The algorithm determines a Pareto-front of optimal ablation distributions for three patient datasets. It considers multiple objectives and determines optimal robot parameters for multiple trajectories to access the tumor volume. Conclusions: We prove the effectiveness of our planning procedure to enable the treatment of irregularly shaped brain tumors. Multiple trajectories further increase the applicability of the procedure. |