Magnetic Interactions of Neighbouring Stator Sets in Multi DOF Local Electromagnetic Actuation for Robotic Abdominal Surgery

This paper aims to characterise the magnetic interaction in neighbouring sets of local electromagnetic actuation (LEMA) actuators in a robotic platform for abdominal surgery. The analysis looks into the affect of the magnetic fields contributed by a stator-rotor set (the actuation unit) located adjacent to the rotor of interest. Each rotor drives one of the degree-of-freedoms (DOFs) on a surgical robotic device. In this study, a two-DOF setup is used for the magnetic interaction analysis, which can be expanded to general case n-DOF setup with the Principle of Superposition of magnetic fields from multiple sources. The magnetic model is then used to compute the dynamics of the system, which involves the equation of motion of the rotors and associated robotic mechanism it drives, and the actuator (electrical) model that takes into account the back EMF generated by the permanent magnet rotors. The magnetic field effect of the neighbouring set onto the rotor is observed by obtaining the speed response of the rotor through simulation so that the dynamic model can be validated against the experimental results. The outcomes are useful for the design specification of the LEMA system configuration, involving the feasible / pragmatic distance between the stator sets such that the interference is minimised, and for the design of the necessary control strategy

Disturbance Rejection in Multi-DOF Local Magnetic Actuation for Robotic Abdominal Surgery

The potential of multi-degrees-of-freedom (DOFs) local magnetic actuation (LMA) has been established in recent years for dexterous minimally invasive surgical manipulations. Nonetheless, having multiple magnetic based units, one for each DOF, within a close vicinity to each other leads to magnetic field interaction among the magnetic sources, hence, resulting in a disturbance to a given LMA unit. It is further realized that the disturbance is a result of actuation effort by the neighboring magnetic sources forming the LMA units, and that the actuation command to all LMA units is a known information to the controller. Therefore, partial information of the disturbance is known and can be exploited in a disturbance rejection strategy. In this letter, this disturbance is modeled and used to augment a simplified model of the systems dynamics of the LMA-based surgical manipulators. The internal model principle (IMP) strategy is selected in which an observer is designed to estimate the disturbance to be rejected. Numerical simulation as well as experimental validation were performed to validate the efficacy of the IMP. The results serve to remove a significant technical hurdle in bringing the new emerging technique of LMA into practical reality for abdominal surgeries

Robustness Evaluation of Internal Model Principle-based Controller in a Magnetically Actuated Surgical System

The local magnetic actuation (LMA) surgical method has gained popularity among medical practitioners and researchers in the field of abdominal surgery. The procedure requires the use of magnets on both sides of the abdominal cavity to anchor devices onto abdominal wall while magnetic sources on the external side generate actuation signals to drive robotic manipulators inside the cavity. Due to the transmission of magnetic fields across the abdominal wall and the interactions among multiple LMA units within the vicinity, magnetic interference will affect the performance of the intended rotor driving the degree-of-freedom (DOF) on the robotic manipulator. Since the disturbances due to the neighbouring magnetic sources are found to be sinusoidal signals with a known frequency, they can be rejected by using the internal model principle (IMP) technique. The disturbance due to the abdominal wall tissue dynamics during magnetic actuation causes oscillations on the internally anchored surgical device, which has generally been ignored in the implementation of LMA application. The focus of this paper is to provide a model that incorporates tissue dynamics in the LMA system. Moreover, the robustness of IMP controller in the presence of tissue dynamics is discussed. Simulations are performed and the results demonstrate effective rejection of both disturbances when they are taken into account in the IMP disturbance model

Development of A Soft Robotic Approach for An Intra-abdominal Wireless Laparoscopic Camera

In Single-Incision Laparoscopic Surgery (SILS), the Magnetic Anchoring and Guidance System (MAGS) arises as a promising technique to provide larger workspaces and field of vision for the laparoscopes, relief space for other instruments, and require fewer incisions. Inspired by MAGS, many concept designs related to fully insertable magnetically driven laparoscopes are developed and tested on the transabdominal operation. However, ignoring the tissue interaction and insertion procedure, most of the designs adopt rigid structures, which not only damage the patients\u27 tissue with excess stress concentration and sliding motion but also require complicated operation for the insertion. Meanwhile, lacking state tracking of the insertable camera including pose and contact force, the camera systems operate in open-loop control. This provides mediocre locomotion precision and limited robustness to uncertainties in the environment. This dissertation proposes, develops, and validates a soft robotic approach for an intra-abdominal wireless laparoscopic camera. Contributions presented in this work include (1) feasibility of a soft intra-abdominal laparoscopic camera with friendly tissue interaction and convenient insertion, (2) six degrees of freedom (DOF) real-time localization, (3) Closed-loop control for a robotic-assisted laparoscopic system and (4) untethering solution for wireless communication and high-quality video transmission. Embedding magnet pairs into the camera and external actuator, the camera can be steered and anchored along the abdominal wall through transabdominal magnetic coupling. To avoid the tissue rapture by the sliding motion and dry friction, a wheel structure is applied to achieve rolling motion. Borrowing the ideas from soft robotic research, the main body of the camera implements silicone material, which grants it the bendability to passively attach along the curved abdominal wall and the deformability for easier insertion. The six-DOF pose is estimated in real-time with internal multi-sensor fusion and Newton-Raphson iteration. Combining the pose tracking and force-torque sensor measurement, an interaction model between the deformable camera and tissue is established to evaluate the interaction force over the tissue surface. Moreover, the proposed laparoscopic system is integrated with a multi-DOF manipulator into a robotic-assisted surgical system, where a closed-loop control is realized based on a feedback controller and online optimization. Finally, the wireless control and video streaming are accomplished with Bluetooth Low Energy (BLE) and Analog Video (AV) transmission. Experimental assessments have been implemented to evaluate the performance of the laparoscopic system

Engineering Dynamics and Life Sciences

From Preface: This is the fourteenth time when the conference “Dynamical Systems: Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our invitation has been accepted by recording in the history of our conference number of people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all over the world. They decided to share the results of their research and many years experiences in a discipline of dynamical systems by submitting many very interesting papers. This year, the DSTA Conference Proceedings were split into three volumes entitled “Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and Engineering Dynamics and Life Sciences. Additionally, there will be also published two volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems in Theoretical Perspective” and “Dynamical Systems in Applications”

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version