publications
publications by categories in reversed chronological order. generated by jekyll-scholar.
2023
- Robot Haptics for Robust and Resilient Autonomous Non-prehensile ManipulationO. Tokatli, and W. Harwin2023
@conference{Tokatli2023, author = {Tokatli, O. and Harwin, W.}, title = {Robot Haptics for Robust and Resilient Autonomous Non-prehensile Manipulation}, booktitle = {The International Conference on Robotics and Automation (ICRA) (submitted)}, year = {2023}, }
2022
- Operator performance analysis in tele-manipulationE. J. Lopez Pulgarin, O. Tokatli, G. Burroughes, and G. HerrmannFrontiers (under review), 2022
Tele-manipulation is indispensable for the nuclear industry since teleoperated robots cancel the radiation hazard problem for the operator. The majority of the teleoperated solutions used in the nuclear industry rely on bilateral teleoperation, utilizing a variation of the 4-channel architecture, where the motion and force signals of the local and remote robots are exchanged in the communication channel. However, the performance limitation of teleoperated robots for nuclear decommissioning tasks is not clearly answered in the literature. In this study, we assess the task performance in bilateral tele-manipulation for radiation surveying in gloveboxes and compare it to radiation surveying of a glovebox operator. To analyze the performance, an experimental setup suitable for human operation (manual operation) and tele-manipulation is designed. Our results showed that a current commercial off-the-shelf (COTS) teleoperated robotic manipulation solution is flexible, yet insufficient, as its task performance is significantly lower when compared to manual operation and potentially hazardous for the equipment inside the glovebox. Finally, we propose a set of potential solutions, derived from both our observations and expert interviews, that could improve the performance of teleoperation systems in glovebox environments in future work.
@article{LopezPulgarin2022, author = {Lopez Pulgarin, E. J. and Tokatli, O. and Burroughes, G. and Herrmann, G.}, title = {Operator performance analysis in tele-manipulation}, journal = {Frontiers (under review)}, year = {2022}, doi = {10.3389/frobt.2022.932538}, url = {https://doi.org/10.3389/frobt.2022.932538} }
2021
- Robot-Assisted Glovebox Teleoperation for Nuclear IndustryO. Tokatli, P. Das, R. Nath, L. Pangione, A. Altobelli, G. Burroughes, E. T. Jonasson, M. F. Turner, and R. SkiltonRobotics, 2021
The nuclear industry has some of the most extreme environments in the world, with radiation levels and extremely harsh conditions restraining human access to many facilities. One method for enabling minimal human exposure to hazards under these conditions is through the use of gloveboxes that are sealed volumes with controlled access for performing handling. While gloveboxes allow operators to perform complex handling tasks, they put operators at considerable risk from breaking the confinement and, historically, serious examples including punctured gloves leading to lifetime doses have occurred. To date, robotic systems have had relatively little impact on the industry, even though it is clear that they offer major opportunities for improving productivity and significantly reducing risks to human health. This work presents the challenges of robotic and AI solutions for nuclear gloveboxes, and introduces a step forward for bringing cutting-edge technology to gloveboxes. The problem statement and challenges are highlighted and then an integrated demonstrator is proposed for robotic handling in nuclear gloveboxes for nuclear material handling. The proposed approach spans from tele-manipulation to shared autonomy, computer vision solutions for robotic manipulation to machine learning solutions for condition monitoring.
@article{Tokatli2021a, author = {Tokatli, O. and Das, P. and Nath, R. and Pangione, L. and Altobelli, A. and Burroughes, G. and Jonasson, E. T. and Turner, M. F. and Skilton, R.}, title = {Robot-Assisted Glovebox Teleoperation for Nuclear Industry}, journal = {Robotics}, volume = {10}, year = {2021}, number = {3}, doi = {10.3390/robotics10030085}, url = {https://doi.org/10.3390/robotics10030085} } - Haptic-enabled collaborative learning in virtual reality for schoolsEducation and Information Technologies, 2021
This paper reports on a study which designed and developed a multi-fingered haptic interface in conjunction with a three-dimensional (3D) virtual model of a section of the cell membrane in order to enable students to work collaboratively to learn cell biology. Furthermore, the study investigated whether the addition of haptic feedback to the 3D virtual reality (VR) simulation affected learning of key concepts in nanoscale cell biology for students aged 12 to 13. The haptic interface was designed so that the haptic feedback could be turned on or switched off. Students (N = 64), in two secondary schools, worked in pairs, on activities designed to support learning of specific difficult concepts. Findings from observation of the activities and interviews revealed that students believed that being immersed in the 3D VR environment and being able to feel structures and movements within the model and work collaboratively assisted their learning. More specifically, the pilot/co-pilot model that we developed was successful for enabling collaborative learning and reducing the isolating effects of immersion with a 3D headset. Results of pre and post-tests of conceptual knowledge showed significant knowledge gains but addition of haptic feedback did not affect the knowledge gains significantly. The study enabled identification of important issues to consider when designing and using haptic-enabled 3D VR environments for collaborative learning.
@article{Webb2021, author = {Webb, M. E. and Tracey, M. and Harwin, W. and Tokatli, O. and Hwang, F. and Johnson, R. and Barrett, N. and Jones, C.}, title = {Haptic-enabled collaborative learning in virtual reality for schools}, journal = {Education and Information Technologies}, year = {2021}, volume = {27}, number = {1}, doi = {10.1007/s10639-021-10639-4}, url = {https://doi.org/10.1007/s10639-021-10639-4} } - Optimal Grasping Pose Synthesis in a Constrained EnvironmentA. Altobelli, O. Tokatli, G. Burroughes, and R. SkiltonRobotics, 2021
In the last few decades, several approaches have been presented to accomplish tasks with robots or autonomous systems in a glovebox; nevertheless, in nuclear facilities, risky operations are still executed by humans that guarantee a high manipulation capability and dexterity. Inside the gloveboxes, robotic devices have to operate in cluttered environments, or environments with limited space for movement; therefore, it is of significant interest to identify grasping poses that are feasible within such constrained environments. In this paper, we present and experimentally evaluate a strategy to synthesise optimal grasps considering geometric primitives for a manipulation systems in a constrained environment. The novel strategy has been experimentally evaluated in a cluttered environment (as a glovebox mock-up) with realistic objects, and the efficacy of the proposed grasping algorithm is proposed.
@article{Altobelli2021a, author = {Altobelli, A. and Tokatli, O. and Burroughes, G. and Skilton, R.}, title = {Optimal Grasping Pose Synthesis in a Constrained Environment}, journal = {Robotics}, year = {2021}, volume = {10}, number = {1}, doi = {10.3390/robotics10010004}, url = {https://doi.org/10.3390/robotics10010004} } - Physical Human-Robot Interaction Using HANDSON-SEA: An Educational Robotic Platform with Series Elastic ActuationA. Otaran, O. Tokatli, and V. PatogluIEEE Transactions on Haptics, 2021
For gaining proficiency in physical human-robot interactions, it is crucial for engineering students to be provided with the opportunity to gain hands-on experience with robotic devices that feature kinesthetic feedback. In this article, we propose HandsOn-SEA, a low-cost, single degree-of-freedom, force-controlled educational robot with series elastic actuation and introduce educational modules for the use of the device to allow students to experience the fundamental performance trade-offs inherent in robotic systems. The novelty of the proposed robot is due to the deliberate introduction of a compliant element between the actuator and the handle, whose deflections are measured to perform closed-loop force control. As an admittance-type robot, HandsOn-SEA relies on force feedback to achieve the desired level of safety and transparency and complements the existing impedance-type educational robots. We present the integration of HandsOn-SEA into the robotics curriculum, by providing guidelines for its use in a senior level robotics course, to help students experience the challenges involved in the synergistic design and control of robotic devices. We systematically evaluate the efficacy of the device in a robotics course delivered for five semesters and provide evidence that HandsOn-SEA is effective in instilling fundamental concepts and trade-offs in the design and control of robotic devices.
@article{Otaran2021, author = {Otaran, A. and Tokatli, O. and Patoglu, V.}, title = {Physical Human-Robot Interaction Using HANDSON-SEA: An Educational Robotic Platform with Series Elastic Actuation}, journal = {IEEE Transactions on Haptics}, year = {2021}, volume = {14}, number = {4}, doi = {10.1109/TOH.2021.3081982}, url = {https://doi.org/10.1109/TOH.2021.3081982} }
2020
- A Computational Multi-criteria Optimization Approach to Interaction Controller Design for pHRI SystemsTransactions on Robotics, 2020
Physical human-robot interaction (pHRI) integrates the benefits of human operator and a collaborative robot in tasks involving physical interaction, with the aim of increasing the task performance. However, the design of interaction controllers that achieve safe and transparent operations is challenging, mainly due to the contradicting nature of these objectives. Knowing that attaining perfect transparency is practically unachievable, controllers that allow better compromise between these objectives are desirable. In this article, we propose a multicriteria optimization framework, which jointly optimizes the stability robustness and transparency of a closed-loop pHRI system for a given interaction controller. In particular, we propose a Pareto optimization framework that allows the designer to make informed decisions by thoroughly studying the tradeoff between stability robustness and transparency. The proposed framework involves a search over the discretized controller parameter space to compute the Pareto front curve and a selection of controller parameters that yield maximum attainable transparency and stability robustness by studying this tradeoff curve. The proposed framework not only leads to the design of an optimal controller, but also enables a fair comparison among different interaction controllers. In order to demonstrate the practical use of the proposed approach, integer and fractional order admittance controllers are studied as a case study and compared both analytically and experimentally. The experimental results validate the proposed design framework and show that the achievable transparency under fractional order admittance controller is higher than that of integer order one, when both controllers are designed to ensure the same level of stability robustness.
@article{Aydin2020a, author = {Aydin, Y. and Tokatli, O. and Patoglu, V. and Basdogan, C.}, title = {A Computational Multi-criteria Optimization Approach to Interaction Controller Design for pHRI Systems}, journal = {Transactions on Robotics}, year = {2020}, volume = {36}, number = {6}, doi = {10.1109/TRO.2020.2998606}, url = {https://doi.org/10.1109/TRO.2020.2998606} } - A Variable-Fractional Order Admittance Controller for pHRI2020
In today’s automation driven manufacturing environments, emerging technologies like cobots (collaborative robots) and augmented reality interfaces can help integrating humans into the production workflow to benefit from their adaptability and cognitive skills. In such settings, humans are expected to work with robots side by side and physically interact with them. However, the trade-off between stability and transparency is a core challenge in the presence of physical human robot interaction (pHRI). While stability is of utmost importance for safety, transparency is required for fully exploiting the precision and ability of robots in handling labor intensive tasks. In this work, we propose a new variable admittance controller based on fractional order control to handle this trade-off more effectively. We compared the performance of fractional order variable admittance controller with a classical admittance controller with fixed parameters as a baseline and an integer order variable admittance controller during a realistic drilling task. Our comparisons indicate that the proposed controller led to a more transparent interaction compared to the other controllers without sacrificing the stability. We also demonstrate a use case for an augmented reality (AR) headset which can augment human sensory capabilities for reaching a certain drilling depth otherwise not possible without changing the role of the robot as the decision maker.
@conference{Sirintuna2020, author = {Sirintuna, D. and Aydin, Y. and Caldiran, O. and Tokatli, O. and Patoglu, V. and Basdogan, C.}, title = {A Variable-Fractional Order Admittance Controller for pHRI}, booktitle = {The International Conference on Robotics and Automation (ICRA)}, year = {2020}, doi = {10.1109/ICRA40945.2020.9197288}, url = {https://doi.org/10.1109/ICRA40945.2020.9197288} }
2019
- An Investigation of the Impact of Haptics for Promoting Understanding of Difficult Concepts in Cell Biology2019
This paper reports on a study which investigated whether the addition of haptics (virtual touch) to a three-dimensional (3D) virtual reality (VR) simulation promotes learning of key concepts in biology for students aged 12 to 13 years. We developed a virtual model of a section of the cell membrane and a haptic-enabled interface that allows students to interact with the model and to manipulate objects in the model. Students, in two schools in England, worked collaboratively on activities, in pairs, designed to support learning of key difficult concepts. These concepts included the dynamic nature of the cell membrane, passive diffusion and facilitated diffusion. Findings from observation of the activities and student interviews revealed that students were very positive about using the system and believed that being able to feel structures and movements within the model assisted their learning. Results of pre- and post-tests of conceptual knowledge showed significant knowledge gains but there were no significant differences between the haptic and non-haptic condition.
@conference{Webb2019a, author = {Webb, M. and Tracey, M. and Harwin, W. and Tokatli, O. and Hwang, F. and Barrett, N. and Jones, C. and Johnson, R.}, title = {An Investigation of the Impact of Haptics for Promoting Understanding of Difficult Concepts in Cell Biology}, year = {2019}, booktitle = {Open Conference on Computers in Education}, doi = {10.1007/978-3-030-23513-0_20}, url = {https://doi.org/10.1007/978-3-030-23513-0_20} } - Design Considerations for Haptic-Enabled Virtual Reality Simulation for Interactive Learning of Nanoscale Science in Schools2019
This paper reports on a study which investigated whether the addition of haptics (virtual touch) to a 3D virtual reality (VR) simulation promotes understanding of key nanoscale concepts in membrane systems for students aged 12 to 13. We developed a virtual model of a section of the cell membrane and a haptic enabled interface that enables students to interact with the model and to manipulate objects in the model. Students, in two schools in England, worked collaboratively in pairs on activities designed to develop their understanding of key concepts of cell membrane function. Results of pre-and post-tests of conceptual knowledge and understanding showed significant knowledge gains but there were no significant differences between the haptic and non-haptic condition. However, findings from observation of the activities and student interviews revealed that students were very positive about using the system and believed that being able to feel structures and manipulate objects within the model assisted their learning. We examine some of the design challenges and issues affecting the perception of haptic feedback.
@conference{Webb2019b, author = {Webb, M. and Tracey, M. and Harwin, W. and Tokatli, O. and Hwang, F. and Johnson, R. and Barrett, N. and Jones, C.}, title = {Design Considerations for Haptic-Enabled Virtual Reality Simulation for Interactive Learning of Nanoscale Science in Schools}, year = {2019}, booktitle = {International Conference on Immersive Learning}, doi = {10.1007/978-3-030-23089-0_5}, url = {https://doi.org/10.1007/978-3-030-23089-0_5} }
2018
- Stable Physical Human-Robot Interaction Using Fractional Order Admittance ControlIEEE Transactions on Haptics, 2018
In the near future, humans and robots are expected to perform collaborative tasks involving physical interaction in various environments, such as homes, hospitals, and factories. Robots are good at precision, strength, and repetition, while humans are better at cognitive tasks. The concept, known as physical human-robot interaction (pHRI), takes advantage of these abilities and is highly beneficial by bringing speed, flexibility, and ergonomics to the execution of complex tasks. Current research in pHRI focuses on designing controllers and developing new methods which offer a better tradeoff between robust stability and high interaction performance. In this paper, we propose a new controller, fractional order admittance controller, for pHRI systems. The stability and transparency analyses of the new control system are performed computationally with human-in-the-loop. Impedance matching is proposed to map fractional order control parameters to integer order ones, and then the stability robustness of the system is studied analytically. Furthermore, the interaction performance is investigated experimentally through two human subject studies involving continuous contact with linear and nonlinear viscoelastic environments. The results indicate that the fractional order admittance controller can be made more robust and transparent than the integer order admittance controller and the use of fractional order term can reduce the human effort during tasks involving contact interactions with environment.
@article{Aydin2018, author = {Aydin, Y. and Tokatli, O. and Patoglu, V. and Basdogan, C.}, title = {Stable Physical Human-Robot Interaction Using Fractional Order Admittance Control}, journal = {IEEE Transactions on Haptics}, year = {2018}, volume = {11}, number = {3}, doi = {10.1109/TOH.2018.2810871}, url = {https://doi.org/10.1109/TOH.2018.2810871} } - HandsOn-Computing: Promoting Algorithmic Thinking Through Haptic Educational RobotsA. Otaran, O. Tokatli, and V. Patoglu2018
Computational thinking lies at the intellectual core of computing. Promoting computational thinking ability requires that students are provided with a clear understanding of the fundamental principles and concepts of computer science, including abstraction, logic, algorithms, and data representation. We propose to use force-feedback educational robotic devices for hands-on teaching of computational thinking. The addition of haptic feedback for teaching abstract concepts of computer science offers several advantages, as haptic feedback (i) enables an effective means of data hiding, (ii) ensures a high level of student engagement by adding another pathway for perception and enabling active physical interaction, and (iii) improves student motivation through the novelty effect. Moreover, visually impaired students may benefit from replacement of visualization with haptic feedback. We present a force-feedback application for teaching sorting algorithms and report initial student evaluations of integrating haptics to promote computational thinking.
@conference{Otaran2018b, author = {Otaran, A. and Tokatli, O. and Patoglu, V.}, title = {HandsOn-Computing: Promoting Algorithmic Thinking Through Haptic Educational Robots}, booktitle = {EuroHaptics}, year = {2018}, doi = {10.1007/978-3-319-93399-3_48}, url = {https://doi.org/10.1007/978-3-319-93399-3_48} } - A Classroom Deployment of a Haptic System for Learning Cell Biology2018
@conference{Tokatli2018c, author = {Tokatli, O. and Tracey, M. and Hwang, F. and Barrett, N. and Jones, C. and Webb, M. and Harwin, W.}, title = {A Classroom Deployment of a Haptic System for Learning Cell Biology}, booktitle = {EuroHaptics}, year = {2018}, }
2017
- Fractional Order Admittance Control for Physical Human-Robot Interaction2017
@conference{Aydin2017, author = {Aydin, Y. and Tokatli, O. and Patoglu, V. and Basdogan, C.}, title = {Fractional Order Admittance Control for Physical Human-Robot Interaction}, booktitle = {IEEE World Haptics}, year = {2017}, } - The potential for haptic-enabled interaction to support collaborative learning in school biology2017
This paper discusses the rationales and design considerations for developing the use of haptics (virtual touch) for learning aspects of cell biology in secondary schools. The paper considers issues in understanding concepts in cell biology and how a 3-D environment enabled by haptics could support learning of difficult concepts. In this endeavour, a number of educational and design challenges need to be addressed. First we need to identify the level of detail and realism that will support learning and visualisation rather than confuse through its overcomplexity or create misconceptions through oversimplification. Secondly we need to integrate the use of the 3-D environment into classroom teaching by identifying relevant curriculum and pedagogical challenges and solutions. Significant design challenges include navigating the content and scale changes involved in moving between the visible, microscopic and nanoscale in an intuitive and realistic way and enabling collaborative learning.
@conference{Webb2017, author = {Webb, M. and Tracey, M. and Harwin, W. and Tokatli, O. and Hwang, F. and Johnson, R. and Barrett, N. and Jones, C.}, title = {The potential for haptic-enabled interaction to support collaborative learning in school biology}, booktitle = {Society for Information Technology and Teacher Education}, year = {2017}, url = {https://www.learntechlib.org/primary/p/177885/} }
2016
- Hands-On Learning with a Series Elastic Educational RobotA. Otaran, O. Tokatli, and V. Patoglu2016
@conference{Otaran2016, author = {Otaran, A. and Tokatli, O. and Patoglu, V.}, title = {Hands-On Learning with a Series Elastic Educational Robot}, booktitle = {EuroHaptics}, year = {2016}, }
2015
- Generalized Virtual Environment Models for Haptic RenderingO. Tokatli, and V. Patoglu2015
@conference{Tokatli2015a, author = {Tokatli, O. and Patoglu, V.}, title = {Generalized Virtual Environment Models for Haptic Rendering}, booktitle = {Symposium on Theory of Machines and Mechanisms(TrISToMM)}, year = {2015}, } - Stability of Haptic Systems with Fractional Order ControllersO. Tokatli, and V. Patoglu2015
Fractional order calculus is a generalization of the familiar integer order calculus in that, it allows for differentiation/integration with orders of any real number. The use of fractional order calculus in systems and control applications provides the user an extra design variable, the order of differointegration, which can be tuned to improve the desired behavior of the overall system. We propose utilization of fractional order models/controllers in haptic systems and study the effect of fractional differentiation order on the stability robustness of the overall sampled-data system. Our results demonstrate that fractional calculus generalization has a significant impact on both the shape and area of stability region of a haptic system and inclusion of fractional order impedances may improve the stability robustness of haptic rendering. Our results also include experimental verification of the stability regions predicted by the theoretical analysis.
@conference{Tokatli2015b, author = {Tokatli, O. and Patoglu, V.}, title = {Stability of Haptic Systems with Fractional Order Controllers}, booktitle = {IEEE/RSJ International Conference on Intelligent Robotsand Systems (IROS)}, year = {2015}, doi = {10.1109/IROS.2015.7353518}, url = {https://doi.org/10.1109/IROS.2015.7353518} } - Using Fractional Order Elements for Haptic RenderingO. Tokatli, and V. Patoglu2015
Fractional order calculus—a generalization of the traditional calculus to arbitrary order differointegration—is an effective mathematical tool that broadens the modeling boundaries of the familiar integer order calculus. Fractional order models enable faithful representation of viscoelastic materials that exhibit frequency dependent stiffness and damping characteristics within a single mechanical element. We propose the use of fractional order models/controllers in haptic systems to significantly extend the type of impedances that can be rendered using the integer order models. We study the effect of fractional order elements on the coupled stability of the overall sampled-data system. We show that fractional calculus generalization provides an additional degree of freedom for adjusting the dissipation behavior of the closed-loop system and generalize the well-known passivity condition to include fractional order impedances. Our results demonstrate the effect of the order of differointegration on the passivity boundary. We also characterize the effective impedance of the fractional order elements as a function of frequency and differointegration order.
@conference{Tokatli2015c, author = {Tokatli, O. and Patoglu, V.}, title = {Using Fractional Order Elements for Haptic Rendering}, booktitle = {International Symposium on Robotics Research (ISRR)}, year = {2015}, doi = {10.1007/978-3-319-51532-8_23}, url = {https://doi.org/10.1007/978-3-319-51532-8_23} } - Fractional order control in hapticsO. TokatliSabanci University, 2015
Fractional order (FO) calculus—a generalization of the traditional calculus to arbitrary order differointegration-is an effective mathematical tool that broadens the modeling boundaries of the familiar integer order calculus. The effectiveness of this remarkable mathematical tool has been observed in many practical applications. For instance, FO models enable faithful representation of viscoelastic materials that exhibit frequency dependent stiffness and damping characteristics within a single mechanical element. In this dissertation, we propose and analyze the use of FO controllers in haptic systems and provide a systematic analysis of this new control method in the light of the fundamental trade-off between the stability robustness and the transparency performance. FO controllers provide a promising generalization that allows one to better shape the frequency response of a system to achieve more favorable robustness and performance characteristics. In particular, the use of FO calculus in systems and control applications provides the user with an extra design variable, the order of differointegration, which can be tuned to improve the desired behavior of the overall system. We introduce a generalized FO nondimensionalized sampled-data model for the haptic system and study its frequency dependent behaviour. Then, we analyze the stability of this system with and without a human operator in the loop. Moreover, we experimentally verify the stability analysis and demonstrate that the experiments capture the essence of the stability behaviour between different differentiation orders. The passivity analysis is conducted for two cases: the first approach takes the environment model into account and ensures the passivity of the haptic system together with the virtual environment, while the second approach assumes the presence of a passive environment model in the control loop and introduces a controller to the closed-loop system that acts like a buffer between the haptic display and the virtual environment. The second approach is more suitable for complex environments as it investigates the passivity properties of the two-port haptic system together with a virtual coupler. After characterizing the stability boundaries for the FO haptic system, we analyse the performance of the system by studying the transparency performance of the haptic rendering with such controllers. In particular, we employ effective impedance analysis to decompose the closed-loop impedance of a haptic system into its parts and study the contribution of FO elements on the stiffness and damping rendering characteristics of the system. Finally, we apply the theoretical results to a novel haptic rendering scenario: haptic rendering of viscoelastic materials. A fractional order mathematical model for the human prostate tissue with history depended stress and deflection behavior, is chosen as the viscoelastic physical system to be rendered. The stress relaxation of the haptic rendering is verified against the experimental data, indicating a high fidelity rendering.
@phdthesis{Tokatli_phd, author = {Tokatli, O.}, title = {Fractional order control in haptics}, school = {Sabanci University}, year = {2015}, address = {Istanbul, Turkey}, url = {https://research.sabanciuniv.edu/id/eprint/34535} }
2011
- Design of a Compliant Manipulator for Removing Malign Cancer Tissue Through Hydrodynamic CavitationO. Tokatli, and V. Patoglu2011
@conference{Tokatli2011a, author = {Tokatli, O. and Patoglu, V.}, title = {Design of a Compliant Manipulator for Removing Malign Cancer Tissue Through Hydrodynamic Cavitation}, booktitle = {ECCOMAS Multibody Dynamics}, year = {2011}, } - Series Elastic Actuation for Force Controlled Micro-ManipulationO. Tokatli, and V. Patoglu2011
@conference{Tokatli2011b, author = {Tokatli, O. and Patoglu, V.}, title = {Series Elastic Actuation for Force Controlled Micro-Manipulation}, booktitle = {IEEE International Conference on Mechatronics}, year = {2011}, doi = {10.1109/ICMECH.2011.5971323}, url = {https://doi.org/10.1109/ICMECH.2011.5971323}, abstact = {We propose using series elastic actuation (SEA) in micro mechanical devices to achieve precise control of the interaction forces. Using μSEA for force control removes the need for high-precision force sensors/actuators and allows for accurate force control through simple position control of the deflection of a compliant coupling element. In this work, we employ a design optimization framework to design this element. The proposed design framework ensures robustness of the design while simultaneously optimizing multiple objective functions. The robust design optimization method relies on the Sensitivity Region concept which minimizes the change of the objective function with respect to the small changes in the design variables. Once the optimal design is obtained, a non-overshooting controller is implemented for the μSEA to achieve accurate force tracking without ever exceeding the reference force input.} }
2010
- Nonovershooting Force Control of a Series Elastic ActuatorO. Tokatli, and V. PatogluSolid State Phenomenon, 2010
Whenever mechanical devices are used to interact with the environment, accurate control of the forces occurring at the interaction surfaces arises as an important challenge. Traditionally, force controlled systems utilize stiff force sensors in the feedback loop to measure and regulate the interaction forces. Series elastic actuation (SEA) is an alternative approach to force control, in which the deflection of a compliant element (orders of magnitude less stiff than a typical force sensor) placed between motor and the environment is controlled to regulate the interaction forces. The use of SEAs for force control is advantageous, since this approach possesses inherent robustness without the need for high-precision force sensors/actuators and allows for the accurate control of the force exerted by the actuator through position control of the deflection of a compliant coupling element. Here, a non-overshooting force controller is proposed to be embedded into the control structure of SEAs. Such controller architecture ensures safe operations of SAEs by making sure that the force applied to the environment are always bounded from above by the reference forces commanded to the controller.
@article{Tokatli2010f, author = {Tokatli, O. and Patoglu, V.}, title = {Nonovershooting Force Control of a Series Elastic Actuator}, journal = {Solid State Phenomenon}, year = {2010}, volume = {166}, doi = {10.4028/www.scientific.net/SSP.166-167.421}, url = {https://doi.org/10.4028/www.scientific.net/SSP.166-167.421} } - Nonovershooting Force Control of a Series Elastic ActuatorO. Tokatli, and V. Patoglu2010
@conference{Tokatli2010a, author = {Tokatli, O. and Patoglu, V.}, title = {Nonovershooting Force Control of a Series Elastic Actuator}, booktitle = {IEEE International Conference on Mechatronics}, year = {2010}, } - Optimal Design of a Series Elastic ActuatorO. Tokatli, and V. Patoglu2010
We propose using series elastic actuation (SEA) in micro mechanical devices to achieve precise control of the interaction forces. Using μSEA for force control removes the need for high-precision force sensors/actuators and allows for accurate force control through simple position control of the deflection of a compliant coupling element. Since the performance of a μSEA is highly dependent on the design of this compliant coupling element, we employ a design optimization framework to design this element. In particular, we propose a compliant, under-actuated half-pantograph mechanism as a feasible kinematic structure for this coupling element. Then, we consider multiple design objectives to optimize the performance of this compliant mechanism through dimensional synthesis, formulating an optimization problem to study the trade-offs between these design criteria. We optimize the directional manipulability of the mechanism, simultaneously with its task space stiffness, using a Pareto-front based framework. We select an optimal design by studying solutions on the Pareto-front curve and considering the linearity of the stiffness along the actuation direction as a secondary design criteria. The optimized mechanism possesses high manipulability and low stiffness along the movement direction of the actuator; hence, achieves a large stroke with high force resolution. At the same time, the mechanism has low manipulability and high stiffness along the direction perpendicular to the actuator motion, ensuring good disturbance rejection characteristics. We model the behavior of this compliant mechanism and utilize this model to synthesize a controller for μSEA to study its dynamic response. Simulated closed loop performance of the μSEA with optimized coupling element indicates that force references can be tracked without significant overshoot and with low tracking error (about 1.1%) even for periodic reference signals.
@conference{Tokatli2010b, author = {Tokatli, O. and Patoglu, V.}, title = {Optimal Design of a Series Elastic Actuator}, booktitle = {ASME International Design Engineering Technical Conferences and Computers and Information Engineering Conference}, year = {2010}, doi = {10.1115/DETC2010-28336}, url = {https://doi.org/10.1115/DETC2010-28336} } - Robust Optimal Design of a Micro GripperO. Tokatli, and V. Patoglu2010
@conference{Tokatli2010c, author = {Tokatli, O. and Patoglu, V.}, title = {Robust Optimal Design of a Micro Gripper}, booktitle = {The First Joint Conference on Multibody System Dynamics}, year = {2010}, } - Robust Optimal Design of a Micro Series Elastic ActuatorO. Tokatli, and V. Patoglu2010
@conference{Tokatli2010d, author = {Tokatli, O. and Patoglu, V.}, title = {Robust Optimal Design of a Micro Series Elastic Actuator}, booktitle = {AzCIFToMM International Symposium of Mechanisms and Machine Science}, year = {2010}, } - Seri Elastik Eyleyicinin Tasarimi ve Denetimi (Design and Control of a Series Elastic Actuator)O. Tokatli, and V. Patoglu2010
@conference{Tokatli2010e, author = {Tokatli, O. and Patoglu, V.}, title = {Seri Elastik Eyleyicinin Tasarimi ve Denetimi (Design and Control of a Series Elastic Actuator)}, booktitle = {Otomatik Kontrol Ulusal Toplantisi}, year = {2010}, } - Robust optimal design and control of a micro series elastic actuatorO. TokatliSabanci University, 2010
Micro mechanical devices are becoming ubiquitous as they find increasing uses in applications such as micro-fabrication, micro-surgery and micro- probing. Use of micro-electromechanical systems not only offer compactness and precision, but also increases the efficiency of processes. Whenever me- chanical devices are used to interact with the environment, accurate control of the forces arising at the interaction surfaces arise as an important chal- lenge. In this work, we propose using a series elastic actuation (SEA) for micro- manipulation. Since an SEA is an integrated mechatronic device, the me- chanical design and controller synthesis are handled in parallel to achieve the best overall performance. The mechanical design of the μSEA is handled in two steps: type selection and dimensional synthesis. In the type selection step, a compliant, half pantograph mechanism is chosen as the underlying kinematic structure of the coupling element. For optimal dimensioning, the bandwidth of the system, the disturbance response and the force resolution are considered to achieve good control performance with high reliability. These objectives are achieved by optimizing the manipulability and the stiffness of the mechanism along with a robustness constraint. In parallel with the mechanical design, a force controller is synthesized. The controller has a cascaded structure: an inner loop for position control and an outer loop for force control. Since excess force application can be detrimental during manipulation of fragile objects; the position controller of the inner loop is designed to be a non-overshooting controller which guar- antees the force response of the system always stay lower than the reference value. This self-standing μSEA system is embedded into a 3-channel scaled tele- operation architecture so that an operator can perform micro-telemanipulation. Constant scaling between the master and the slave is implemented and the teleoperator controllers preserve the non-overshooting nature of the μSEA. Finally, the designed μSEA based micro-telemanipulation system is im- plemented and characterized.
@mastersthesis{Tokatli_master, author = {Tokatli, O.}, title = {Robust optimal design and control of a micro series elastic actuator}, school = {Sabanci University}, year = {2010}, address = {Istanbul, Turkey}, url = {https://research.sabanciuniv.edu/id/eprint/21437} }
2009
- Multi-Criteria Optimization of a Compliant Half PantographO. Tokatli, and V. Patoglu2009
@conference{Tokatli2009, author = {Tokatli, O. and Patoglu, V.}, title = {Multi-Criteria Optimization of a Compliant Half Pantograph}, booktitle = {ECCOMAS Multibody Dynamics}, year = {2009}, }