Minimally Invasive Therapy. 2015;24:18–23
ORIGINAL ARTICLE
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Robotic natural orifice transluminal endoscopic surgery (R-NOTES): Literature review and prototype system
BAMSHAD AZIZI KOUTENAEI1,2, EMMANUEL WILSON1, REZA MONFAREDI1, CRAIG PETERS1, GERNOT KRONREIF3 & KEVIN CLEARY1 1
Sheikh Zayed Institute, Children’s National Medical Center, Washington, D.C., USA, 2Technical University of Munich, Munich, Germany, and 3Austrian Center for Medical Innovation and Technology ACMIT, Wiener Neustadt, Austria
Abstract In minimally invasive surgery methods such as laparoscopic surgery, surgical instruments are introduced through small incisions to minimize patient trauma and recovery times. To reduce the number of incisions, new techniques such as natural orifice transluminal endoscopic surgery (NOTES) have been proposed. Compared to laparoscopic surgery, the NOTES approach, which requires new technology and improved instruments, presents some unique challenges. Robotic NOTES (R-NOTES) could be an enabling technology for these procedures. In this paper, we first review relevant work in R-NOTES. We then present our work and the system architecture for an R-NOTES prototype system incorporating wireless command and control. The system was tested twice in swine animal studies.
Key words: Minimally invasive surgery, wireless robotic surgery, NOTES, R-NOTES, magnetic anchoring
Introduction Laparoscopic surgery is a common standard minimally invasive surgery (MIS) technique (1). In comparison with open surgery, where a single large incision is made, laparoscopic surgery uses three to five small incisions (2). The benefits of this approach include reduced patient trauma, morbidity, surgical costs, and improved cosmesis. From a procedural standpoint, the challenges with a laparoscopic approach include reduced dexterity and limited perception of the surgical space, which often leads to increased strain on the surgeon and increased procedure times. Robotic laparoscopic surgery has gained prominence in recent years largely because it addresses some of these challenges. In particular, robotic laparoscopic surgery using the da Vinci system (Intuitive Surgical, Sunnyvale, CA, USA) has become the standard of care in urologic procedures such as prostatectomy (3). Similar systems have been developed in the research domain, which are teleoperated and consist of a master console where the surgeon sits and slave robotic arms that
manipulate the laparoscopic instruments. For example the RAVEN system from the University of Washington has an open architecture that allows the system to be customized for research purposes (4). Common to all these approaches is an endeavor to decrease invasiveness and improve procedural efficiency. Regardless of a manual or robotic approach to laparoscopic surgery, some concerns of limited workspace visualization and limited mobility of tools remain. New approaches such as natural orifice transluminal endoscopic surgery (NOTES) aim to address some of these concerns. By inserting surgical tools through a natural orifice, NOTES mitigates the need for external incisions, although an internal incision may still be needed to gain access to the anatomy of interest. By eliminating external incisions, NOTES procedures may reduce patient trauma, the likelihood of infection, and recovery time (5,6). Early NOTES procedures were done using readily available or marginally modified endoscopic devices. The first NOTES case was a transgastric appendectomy performed by Rao et al. in 2004 (7). Since then,
Correspondence: B. Azizi Koutenaei, Children’s national medical center - Sheikh Zayed Institute for Pediatric Surgical Innovation, 111 Michigan Ave, Washington, DC 20010, USA. E-mail: [email protected] ISSN 1364-5706 print/ISSN 1365-2931 online Ó 2014 Informa Healthcare DOI: 10.3109/13645706.2014.992907
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Robotic natural orifice transluminal endoscopic surgery (R-NOTES) procedures such as transvaginal cholecystectomy (8) and donor nephrectomy (9) have been performed using endoscopic tools. The key challenges in a NOTES procedure include instrument introduction and advancement, tool maneuverability, and adequate visual and haptic feedback. Due to these challenges, robotic technologies have been proposed to alleviate these concerns (10). Manipulating tissue using long, flexible endoscopic tools is necessarily challenging (11). The ability to apply forces on tissue, triangulate tools and the ability to pass multiple instruments simultaneously are limited with an endoscopic approach (12). In-vivo robots have been proposed as an alternative to the use of endoscopic tools. Examples of these approaches include inchworm robotic systems (13), rolling stents (14) and adhesion-based systems (15). While these devices are still in their infancy, they have the potential to reduce clutter in the surgical workspace, while providing similar benefits to natural orifice surgery such as the use of robotic laparoscopic systems for minimally invasive surgery. While several methods have been proposed for anchoring in-vivo robots, the most common approach uses a magnetic anchoring and guidance system (MAGS). Through the use of large external magnets, in-vivo robotic devices can be held and manipulated against the abdominal wall (16). The University of Nebraska-Lincoln developed an intra-abdominal robot for single port surgery with two arms connected to a central body and a laparoscopic camera (17,18). Another intra-abdominal robotic system was developed at the University of Scuola Superiore Sant’Anna in Pisa, Italy. This intra-abdominal robot consists of two arms with six degrees of freedom (DoF) (19). Simulations, evaluation studies and control station implementation have been conducted (20). While most of these in vivo robots use a wired architecture to provide power and signal communication to an external controller, recent interest has evolved to wireless communication and a modular based design (21). Figure 1a – c illustrates several of these systems (22–24). In the remainder of this paper, we present our work in developing an integrated, tele-operated robotic NOTES device. The system consists of a modular and self-sufficient in-vivo robot, coupled using MAGS to a gross positioning component. Wireless communication is achieved through the use of the ZigBee protocol. The system was evaluated in swine animal studies and these results are shown.
a
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c Biopsy grasper
Mobile biopsy robot
Figure 1. State-of-the-art MIS robotic systems: (a) Insertable robotic platform for single port access (SPA) surgery (22), (b) miniature robot for retraction tasks under vision assistance in minimally invasive surgery (23) and (c) in vivo biopsy robot with biopsy grasper (24).
KUKA Robotics, Augsburg, Germany) used for gross positioning. A software application implemented on a standalone PC, called the master control station (MCS), coordinates communication between the gross positioning module and in-vivo robot and maps input device signals to joint actuation, as well as providing system status and monitoring overhead. In the section below, we begin with a brief overview of the systems integration followed by a detailed description of each system component. Integration overview A proposed solution for an integrated and teleoperated R-NOTES system is presented in Figure 2. This system consists of two robotic components: The ex-vivo gross positioning module and an in-vivo fine positioning module. For purposes of safety, reliability and modularity, we developed a single software control framework to control both gross positioning and in-vivo robotic modules. The master control station (MCS) communicates with the input devices (HCI devices: human computer interface). The operator controls all of the system operations through the HCI devices.
Material and methods
Gross positioning module
Our system consists of an in-vivo robotic manipulator (MicroBot) and a 7-DoF serial robot (KUKA LWR;
The gross positioning module consists of the KUKA Light Weight Robot (LWR) coupled with a MAGS
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Integrated system for wireless R-NOTES Master control station (MCS) HCI devices Omni phantom
GUI
Hardware interface
Minim Invasive Ther Allied Technol Downloaded from informahealthcare.com by Imperial College London on 04/07/15 For personal use only.
Space navigator
Gross positioning module
Fine positioning module
KUKA controller
ZigBee coordinator
KUKA robot
Surgeon MAGS MicroBot
Figure 2. Integrated and teleoperated R-NOTES system overview.
module. The goal of this module is to facilitate reliable robot coupling across the abdominal wall, and enable accurate and repeatable intra-abdominal positioning of the MicroBot. This section will first describe the MAGS component, followed by a description of the KUKA LWR positioner, and finally, the software communication method used for gross positioning control.
MAGS component The MAGS component consists of internal and external Neodymium (NdFeB) permanent magnets. The magnetic attraction force between the internal and external magnets serves to couple the in-vivo device across the abdominal wall. The size and shape of the internal magnets embedded within the in-vivo robotic device is determined in large part by the size constraints of the MicroBot. These internal magnets are 9.5 mm diameter 9.5 mm long N52 grade NdFeB permanent magnets. The size and configuration of the external magnets was determined by an earlier study that optimized magnetic anchoring based on weight and size of the MicroBot, while simultaneously minimizing the likelihood of tissue ischemia (25). The external magnets are two comparable grades 25.4 mm diameter 25.4 mm long cylindrical magnets (DX0X0-N52, K&J Magnetics, Jamison, PA, USA) mounted within a machined magnet holder. The external magnet holder is mounted as an endeffector on the KUKA LWR positioner.
KUKA LWR component The KUKA LWR is a 7-DoF serial link robotic arm. This robot was developed by KUKA based on a prototype from the German Institute of Robotics and Mechatronics (26). Each joint is equipped with a torque sensor that allows the robot to sense external forces applied along the length of the robot body. This capability ensures improved safety in a clinical environment where the robot workspace is shared with humans. The controller runs the KUKA operating system and is responsible for actuation of each joint and communication to an external PC. The master control station (MCS) maps surgeon input to appropriate actuation of the KUKA arm by specifying the joint positions, velocity and torque measurements. The commands are transferred through a fast research interface (FRI) link to the control PC. A software program based on the KUKA Robot Language (KRL) framework was developed to communicate between the MCS and controller.
MicroBot The MicroBot in-vivo module serves a similar function in R-NOTES as laparoscopic tools in minimally invasive laparoscopic surgery. The MicroBot is a modular design that is intended to accommodate various tasks depending on the clinical procedure. A fully capable robotic NOTES device will consist of
Robotic natural orifice transluminal endoscopic surgery (R-NOTES) a
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b
Figure 3. (a) R-NOTES MicroBot 1st Prototype - The wires are for electrical power to supplement the on-board ZigBee Circular board and the electrical motor (b) R-NOTES MicroBot 2nd prototype with four DoF.
multiple in-vivo robots, each tailored for a subset of procedural tasks, and controlled remotely by a surgeon (or multiple surgeons). As part of this study, we designed, fabricated and tested two versions of an in-vivo module with a tissue grasper as its endeffector. The constrained space available in the abdominal cavity, combined with the need to concurrently introduce various tools such as laparoscopic cameras and tissue retractors, necessarily implies a small footprint for the MicroBot. To account for rapid development of multiple in-vivo modules we chose a modular hardware design, wherein each DoF is a self-contained entity with actuation, power, and communication capabilities. Based on this same principle of modularity, we implemented a wireless communication architecture that further reduces cable clutter, while enhancing the ability to add additional modules, or vary the complexity of an in-vivo module. The hardware components of the MicroBot are shown in Figure 3 in two configurations. The first version of the MicroBot (Figure 3a) is based on rapid prototype machined links (Objet 500, Stratasys) with the following 3 DoF configuration: pitch, yaw and grasper actuation. Each DoF (with the exception of the grasper) is composed of a flexible rechargeable Lithium polymer 50 mAH battery (PGEB0054050, Powerstream Technology, Orem, UT, USA), brushed DC motor (Series 0615, Faulhaber SA, Croglio, Switzerland), and wireless communication node. For the second version of the MicroBot the robot’s outer diameter was reduced from 23 mm to 16 mm by complete redesign with a high grade of integration and using robot joints made from stainless steel for improved structural stability. Actuation changed to high power density brushed motors DCX10L with gearhead GPX10 1024:1 (Maxon Motor AG, Sachseln, Switzerland). Different from
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the first RP-prototype, this second version does not include any cabling between modules, which also allows a quick and easy re-configuration of the robot kinematic structure. The realised prototype includes four DoF in a pitch – yaw – roll – grasper configuration (Figure 3b). For both MicroBot versions the ZigBee network protocol is used for wireless communication. ZigBee is a mature, low-cost, low-power wireless networking technology that ensures encryption, low latency, and the ability to configure networks dynamically with multiple network nodes, thus being a natural choice for this application. Each robot DoF is a single node and includes a custom circular PCB designed with a Texas Instruments CC2530 microcontroller, MPC17C724 full H-bridge motor controller (Freescale Semiconductor Inc., Austin, TX, USA) and 2.4 GHz chip antenna (Molex, Lisle, IL, USA). The PCB diameter is 14 mm and is well accommodated within the 23 mm (version 1) and the 16 mm (version 2) diameter body of the MicroBot.
Master control station (MCS) The master control station (MCS) is the central software running on a standalone PC that coordinates gross and fine positioning modules, interfaces with user input devices and provides device and status updates. Communication with the KUKA LWR module is achieved through a FRI link over Ethernet. A USB-based ZigBee transceiver, CC2531 USB Dongle (Texas Instruments, Dallas, TX, USA), enables the MCS to communicate with each ZigBee node within the MicroBot. An embedded algorithm was developed using IAR Workbench (IAR Systems AB, Uppsala, Sweden) and implemented on each node to communicate with the MCS and generate pulse width modulated (PWM) signals to actuate the commanded motor. A ZigBee node initialization sequence is initiated when the MicroBot is powered on. This initialization stage assigns unique node addresses to each joint of the MicroBot. Motor actuation commands are generated by the MCS and broadcast over the ZigBee network. Each node listens to broadcast messages, discarding those where addresses do not match. When a node receives a message addressed to it, successful interpretation results in an acknowledgement packet broadcast on the ZigBee network. Thus, the MCS provides status updates and verification if a data packet was sent successfully. Building on this framework, future implementations can encapsulate motor information such as encoder position, or allow haptic feedback.
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Figure 4. KUKA LWR with mounted MAGS module. Laparoscopic video camera is used to visualize in vivo R-NOTES MicroBot (camera view is shown in the middle of the figure).
the MicroBot. A laparoscopic view of the in-vivo module anchored to the abdominal wall is shown in Figure 4. MicroBot movements were observed to mimic MAGS module movements, thus confirming the ability to grossly position the MicroBot inside the body based on KUKA LWR positioning. Gross position adjustments were made until the MicroBot module was located above the liver. To test fine positioning control, user input mapping was toggled to PWM mode within the MCS, thus locking the position of the KUKA LWR and allowing the same 3D mouse input device to be used to control MicroBot actuation. Wireless communication capabilities were tested by actuating each MicroBot node and grasping tissue. Using the laparoscopic camera, it was visually verified that user input was mapped correctly to MicroBot actuation.
Results
Conclusion
In preparation for animal studies, several laboratory assessments and a study in the operating room environment were conducted to assess the reliability and stability of the ZigBee network in a clinical scenario. Two swine studies were then completed to test end-to-end procedure capabilities of the integrated R-NOTES system. The studies were approved by the Children’s Institutional Animal Care and Use Committee. The first test was designed to demonstrate the feasibility of the MAGS and the workspace capability of the KUKA robot to provide gross positioning. The second animal study was to assess the procedural efficacy of the integrated system. An incision was made in the lower abdomen and a hand port (Endopath Dextrus, Ethicon Inc., Somerville, NJ, USA) was placed at the incision site. The hand port was used to enable insertion and retraction of the MicroBot module. The wired version of the MicroBot shown in Figure 3a was used for this study (Figure 3b). The wires provided power alone, with communication done over the ZigBee network. The longer procedure times and multiple trials necessitated the use of a wired module. The MAGS served as an end-effector on the KUKA LWR. The KUKA LWR was maneuvered into position using a 3D navigator mouse until the MAGS module was directly above the swine abdomen (Figure 4). The MAGS module was lowered onto the abdomen and engaged with the MicroBot through the abdominal wall. Using the 3D mouse, the user was able to move the KUKA LWR-MAGS module along craniocaudal and mediolateral axes. A laparoscopic camera, inserted through a side incision, provided visual feedback on the position and movement of
This paper first reviewed related literature and then described our implementation of a teleoperated, integrated robotic NOTES system. We have described the overall system architecture, device implementation, and animal studies. In a cluttered clinical environment with many potential sources of electromagnetic interference, we did not find the wireless ZigBee communication network to be constrained. Future refinement of these systems and concepts may lead to new approaches for robotic NOTES. Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. References 1. Dudrick SJ. Overview of general surgery training in the usa: History and present. Pol J Surg. 2010;82:377–402. 2. Luketich JD, Alvelo-Rivera M, Buenaventura PO, Christie NA, McCaughan JS, Litle VR, et al. Minimally invasive esophagectomy: outcomes in 222 patients. Ann Surg. 2003;238:486. 3. Autorino R, Zargar H, Kaouk JH. Robotic-assisted laparoscopic surgery: recent advances in urology. Fertil Steril. 2014; 102:S0015–282. 4. Hannaford B, Rosen J, Friedman DW, King H, Roan P, Cheng L, et al. Raven-II: an open platform for surgical robotics research. IEEE Trans Biomed Eng. 2013;60:954–9. 5. ASGE/SAGES working group on natural orifice transluminal endoscopic surgery white paper. Gastrointest Endosc. 2006; 63:199–203. 6. Ko CW, Kalloo AN. Per-oral transgastric abdominal surgery. Chin J Dig Dis. 2006;7:67–70. 7. Rao GV, Reddy DN. Transgastric appendectomy in humans. Presented at: World Congress of Gastroenterology; Montreal, Canada; September 2006.
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Robotic natural orifice transluminal endoscopic surgery (R-NOTES) 8. Marescaux J, Dallemagne B, Perretta S, Wattiez A, Mutter D, Coumaros D. Surgery without scars: report of transluminal cholecystectomy in a human being. Arch Surg. 2007;42:823–7. 9. Kaouk JH, Khalifeh A, Laydner H, Autorino R, Hillyer SP, Panumatrassamee K, et al. Transvaginal hybrid natural orifice transluminal surgery robotic donor nephrectomy: first clinical application. Urology. 2012;80:1171–5. 10. Gettman MT, Box G, Averch T, Cadeddu JA, Cherullo E, Clayman RV, et al. Consensus statement on natural orifice transluminal endoscopic urgery and single-incision laparoscopic surgery: heralding a new era in urology? Eur Urol. 2008;53:1117. 11. Abbott DJ, Becke C, Rothstein RI, Peine WJ. Design of an endoluminal notes robotic system. In Intelligent Robots and Systems, IROS 2007, IEEE/RSJ International Conference; 2007. p 410–16. 12. Mummadi RR, Pasricha PJ. The eagle or the snake: platforms for NOTES and radical endoscopic therapy. Gastrointest Endosc Clin N Am. 2008;18:279–89. 13. Dario P, Ciarletta P, Menciassi A, Kim B. Modeling and experimental validation of the locomotion of endoscopic robots in the colon. Int J Robot Res. 2004;23:549–56. 14. Breedveld P, Van der Kouwe DE, Van Gorp MAJ. Locomotion through the intestine by means of rolling stents. In ASME 2004, Design Engineering Technica Conf. Computers Information Engineering Conf, Salt Lake City, UT: 2004. p 963–69. doi:10.1115/DETC2004-57380. 15. Menciassi A, Dario P. Bio-inspired solutions for locomotion in the gastrointestinal tract: background and perspectives. Philos Trans A Math Phys Eng Sci. 2003;361:2287–98. 16. Cadeddu J, Fernandez R, Desai M, Bergs R, Tracy C, Tang SJ, et al. Novel magnetically guided intra-abdominal camera to facilitate laparoendoscopic single-site surgery: initial human experience. Surg Endosc. 2009;23:1894–9. 17. Lehman AC, Dumpert J, Wood NA, Redden L, Visty AQ, Farritor S, et al. Natural orifice cholecystectomy using a miniature robot. Surg Endosc. 2009;23:260–6.
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18. Lehman AC, Wood NA, Farritor S, Goede MR, Oleynikov D. Dexterous miniature robot for advanced minimally invasive surgery. Surg Endosc. 2011;25:119–23. 19. Piccigallo M, Scarfogliero U, Quaglia C, Petroni G, Valdastri P, Menciassi A, et al. Design of a novel bimanual robotic system for single-port laparoscopy. Mechatronics IEEE/ASME Trans. 2010;15:871–8. 20. Sanchez LA, Petroni G, Piccigallo M, Scarfogliero U, Niccolini M, Liu C, et al. Real-time control and evaluation of a teleoperated miniature arm for single port laparoscopy. In Engineering in Medicine and Biology Society, EMBC, 2011 Annual International Conference of the IEEE; 2011. p 7049–53. 21. Tortora G, Salerno M, Ranzani T, Tognarelli S, Dario P, Menciassi A. A modular magnetic platform for natural orifice transluminal endoscopic surgery. Conf Proc IEEE Eng Med Biol Soc. 2013;2013:6265–8. 22. Xu K, Goldman RE, Ding J, Allen PK, Fowler DL, Simaan N. System design of an insertable robotic effector platform for single port access (SPA) surgery. IEEE/RSJ International Conference on Intelligent Robots and Systems; 2009. p 5546–52. 23. Tortora G, Ranzani T, De Falco I, Dario P, Menciassi A. A miniature robot for retraction tasks under vision assistance in minimally invasive surgery. Robotics. 2014;3:70–82. 24. Rentschler ME, Dumpert J, Platt SR, Farritor SM, Oleynikov D. Natural orifice surgery with an endoluminal mobile robot. Surg Endosc. 2007;21:1212–15. 25. Luo H, Wilson E, Cleary K. Simulation, design, and analysis for magnetic anchoring and guidance of instruments for minimally invasive surgery. Proc. SPIE 8316, Medical Imaging 2012: Image-Guided Procedures, Robotic Interventions, and Modeling 2012; 83162K (17 February 2012); doi: 10.1117/12.912013. 26. Hirzinger G, Sporer N, Albu-Schaffer A, Hahnle M, Krenn R, Pascucci A, et al. Dlr’s torque-controlled light weight robot iiiare we reaching the technological limits now? In Robotics and Automation, 2002. Proceedings. ICRA’02; IEEE International Conference On 2002. p 1710–16.
ORIGINAL ARTICLE
Minim Invasive Ther Allied Technol Downloaded from informahealthcare.com by Imperial College London on 04/07/15 For personal use only.
Robotic natural orifice transluminal endoscopic surgery (R-NOTES): Literature review and prototype system
BAMSHAD AZIZI KOUTENAEI1,2, EMMANUEL WILSON1, REZA MONFAREDI1, CRAIG PETERS1, GERNOT KRONREIF3 & KEVIN CLEARY1 1
Sheikh Zayed Institute, Children’s National Medical Center, Washington, D.C., USA, 2Technical University of Munich, Munich, Germany, and 3Austrian Center for Medical Innovation and Technology ACMIT, Wiener Neustadt, Austria
Abstract In minimally invasive surgery methods such as laparoscopic surgery, surgical instruments are introduced through small incisions to minimize patient trauma and recovery times. To reduce the number of incisions, new techniques such as natural orifice transluminal endoscopic surgery (NOTES) have been proposed. Compared to laparoscopic surgery, the NOTES approach, which requires new technology and improved instruments, presents some unique challenges. Robotic NOTES (R-NOTES) could be an enabling technology for these procedures. In this paper, we first review relevant work in R-NOTES. We then present our work and the system architecture for an R-NOTES prototype system incorporating wireless command and control. The system was tested twice in swine animal studies.
Key words: Minimally invasive surgery, wireless robotic surgery, NOTES, R-NOTES, magnetic anchoring
Introduction Laparoscopic surgery is a common standard minimally invasive surgery (MIS) technique (1). In comparison with open surgery, where a single large incision is made, laparoscopic surgery uses three to five small incisions (2). The benefits of this approach include reduced patient trauma, morbidity, surgical costs, and improved cosmesis. From a procedural standpoint, the challenges with a laparoscopic approach include reduced dexterity and limited perception of the surgical space, which often leads to increased strain on the surgeon and increased procedure times. Robotic laparoscopic surgery has gained prominence in recent years largely because it addresses some of these challenges. In particular, robotic laparoscopic surgery using the da Vinci system (Intuitive Surgical, Sunnyvale, CA, USA) has become the standard of care in urologic procedures such as prostatectomy (3). Similar systems have been developed in the research domain, which are teleoperated and consist of a master console where the surgeon sits and slave robotic arms that
manipulate the laparoscopic instruments. For example the RAVEN system from the University of Washington has an open architecture that allows the system to be customized for research purposes (4). Common to all these approaches is an endeavor to decrease invasiveness and improve procedural efficiency. Regardless of a manual or robotic approach to laparoscopic surgery, some concerns of limited workspace visualization and limited mobility of tools remain. New approaches such as natural orifice transluminal endoscopic surgery (NOTES) aim to address some of these concerns. By inserting surgical tools through a natural orifice, NOTES mitigates the need for external incisions, although an internal incision may still be needed to gain access to the anatomy of interest. By eliminating external incisions, NOTES procedures may reduce patient trauma, the likelihood of infection, and recovery time (5,6). Early NOTES procedures were done using readily available or marginally modified endoscopic devices. The first NOTES case was a transgastric appendectomy performed by Rao et al. in 2004 (7). Since then,
Correspondence: B. Azizi Koutenaei, Children’s national medical center - Sheikh Zayed Institute for Pediatric Surgical Innovation, 111 Michigan Ave, Washington, DC 20010, USA. E-mail: [email protected] ISSN 1364-5706 print/ISSN 1365-2931 online Ó 2014 Informa Healthcare DOI: 10.3109/13645706.2014.992907
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Minim Invasive Ther Allied Technol Downloaded from informahealthcare.com by Imperial College London on 04/07/15 For personal use only.
Robotic natural orifice transluminal endoscopic surgery (R-NOTES) procedures such as transvaginal cholecystectomy (8) and donor nephrectomy (9) have been performed using endoscopic tools. The key challenges in a NOTES procedure include instrument introduction and advancement, tool maneuverability, and adequate visual and haptic feedback. Due to these challenges, robotic technologies have been proposed to alleviate these concerns (10). Manipulating tissue using long, flexible endoscopic tools is necessarily challenging (11). The ability to apply forces on tissue, triangulate tools and the ability to pass multiple instruments simultaneously are limited with an endoscopic approach (12). In-vivo robots have been proposed as an alternative to the use of endoscopic tools. Examples of these approaches include inchworm robotic systems (13), rolling stents (14) and adhesion-based systems (15). While these devices are still in their infancy, they have the potential to reduce clutter in the surgical workspace, while providing similar benefits to natural orifice surgery such as the use of robotic laparoscopic systems for minimally invasive surgery. While several methods have been proposed for anchoring in-vivo robots, the most common approach uses a magnetic anchoring and guidance system (MAGS). Through the use of large external magnets, in-vivo robotic devices can be held and manipulated against the abdominal wall (16). The University of Nebraska-Lincoln developed an intra-abdominal robot for single port surgery with two arms connected to a central body and a laparoscopic camera (17,18). Another intra-abdominal robotic system was developed at the University of Scuola Superiore Sant’Anna in Pisa, Italy. This intra-abdominal robot consists of two arms with six degrees of freedom (DoF) (19). Simulations, evaluation studies and control station implementation have been conducted (20). While most of these in vivo robots use a wired architecture to provide power and signal communication to an external controller, recent interest has evolved to wireless communication and a modular based design (21). Figure 1a – c illustrates several of these systems (22–24). In the remainder of this paper, we present our work in developing an integrated, tele-operated robotic NOTES device. The system consists of a modular and self-sufficient in-vivo robot, coupled using MAGS to a gross positioning component. Wireless communication is achieved through the use of the ZigBee protocol. The system was evaluated in swine animal studies and these results are shown.
a
b
rnal Exte dle han
Ext
ern
al h
and
le
c Biopsy grasper
Mobile biopsy robot
Figure 1. State-of-the-art MIS robotic systems: (a) Insertable robotic platform for single port access (SPA) surgery (22), (b) miniature robot for retraction tasks under vision assistance in minimally invasive surgery (23) and (c) in vivo biopsy robot with biopsy grasper (24).
KUKA Robotics, Augsburg, Germany) used for gross positioning. A software application implemented on a standalone PC, called the master control station (MCS), coordinates communication between the gross positioning module and in-vivo robot and maps input device signals to joint actuation, as well as providing system status and monitoring overhead. In the section below, we begin with a brief overview of the systems integration followed by a detailed description of each system component. Integration overview A proposed solution for an integrated and teleoperated R-NOTES system is presented in Figure 2. This system consists of two robotic components: The ex-vivo gross positioning module and an in-vivo fine positioning module. For purposes of safety, reliability and modularity, we developed a single software control framework to control both gross positioning and in-vivo robotic modules. The master control station (MCS) communicates with the input devices (HCI devices: human computer interface). The operator controls all of the system operations through the HCI devices.
Material and methods
Gross positioning module
Our system consists of an in-vivo robotic manipulator (MicroBot) and a 7-DoF serial robot (KUKA LWR;
The gross positioning module consists of the KUKA Light Weight Robot (LWR) coupled with a MAGS
20
B. Azizi Koutenaei et al.
Integrated system for wireless R-NOTES Master control station (MCS) HCI devices Omni phantom
GUI
Hardware interface
Minim Invasive Ther Allied Technol Downloaded from informahealthcare.com by Imperial College London on 04/07/15 For personal use only.
Space navigator
Gross positioning module
Fine positioning module
KUKA controller
ZigBee coordinator
KUKA robot
Surgeon MAGS MicroBot
Figure 2. Integrated and teleoperated R-NOTES system overview.
module. The goal of this module is to facilitate reliable robot coupling across the abdominal wall, and enable accurate and repeatable intra-abdominal positioning of the MicroBot. This section will first describe the MAGS component, followed by a description of the KUKA LWR positioner, and finally, the software communication method used for gross positioning control.
MAGS component The MAGS component consists of internal and external Neodymium (NdFeB) permanent magnets. The magnetic attraction force between the internal and external magnets serves to couple the in-vivo device across the abdominal wall. The size and shape of the internal magnets embedded within the in-vivo robotic device is determined in large part by the size constraints of the MicroBot. These internal magnets are 9.5 mm diameter 9.5 mm long N52 grade NdFeB permanent magnets. The size and configuration of the external magnets was determined by an earlier study that optimized magnetic anchoring based on weight and size of the MicroBot, while simultaneously minimizing the likelihood of tissue ischemia (25). The external magnets are two comparable grades 25.4 mm diameter 25.4 mm long cylindrical magnets (DX0X0-N52, K&J Magnetics, Jamison, PA, USA) mounted within a machined magnet holder. The external magnet holder is mounted as an endeffector on the KUKA LWR positioner.
KUKA LWR component The KUKA LWR is a 7-DoF serial link robotic arm. This robot was developed by KUKA based on a prototype from the German Institute of Robotics and Mechatronics (26). Each joint is equipped with a torque sensor that allows the robot to sense external forces applied along the length of the robot body. This capability ensures improved safety in a clinical environment where the robot workspace is shared with humans. The controller runs the KUKA operating system and is responsible for actuation of each joint and communication to an external PC. The master control station (MCS) maps surgeon input to appropriate actuation of the KUKA arm by specifying the joint positions, velocity and torque measurements. The commands are transferred through a fast research interface (FRI) link to the control PC. A software program based on the KUKA Robot Language (KRL) framework was developed to communicate between the MCS and controller.
MicroBot The MicroBot in-vivo module serves a similar function in R-NOTES as laparoscopic tools in minimally invasive laparoscopic surgery. The MicroBot is a modular design that is intended to accommodate various tasks depending on the clinical procedure. A fully capable robotic NOTES device will consist of
Robotic natural orifice transluminal endoscopic surgery (R-NOTES) a
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b
Figure 3. (a) R-NOTES MicroBot 1st Prototype - The wires are for electrical power to supplement the on-board ZigBee Circular board and the electrical motor (b) R-NOTES MicroBot 2nd prototype with four DoF.
multiple in-vivo robots, each tailored for a subset of procedural tasks, and controlled remotely by a surgeon (or multiple surgeons). As part of this study, we designed, fabricated and tested two versions of an in-vivo module with a tissue grasper as its endeffector. The constrained space available in the abdominal cavity, combined with the need to concurrently introduce various tools such as laparoscopic cameras and tissue retractors, necessarily implies a small footprint for the MicroBot. To account for rapid development of multiple in-vivo modules we chose a modular hardware design, wherein each DoF is a self-contained entity with actuation, power, and communication capabilities. Based on this same principle of modularity, we implemented a wireless communication architecture that further reduces cable clutter, while enhancing the ability to add additional modules, or vary the complexity of an in-vivo module. The hardware components of the MicroBot are shown in Figure 3 in two configurations. The first version of the MicroBot (Figure 3a) is based on rapid prototype machined links (Objet 500, Stratasys) with the following 3 DoF configuration: pitch, yaw and grasper actuation. Each DoF (with the exception of the grasper) is composed of a flexible rechargeable Lithium polymer 50 mAH battery (PGEB0054050, Powerstream Technology, Orem, UT, USA), brushed DC motor (Series 0615, Faulhaber SA, Croglio, Switzerland), and wireless communication node. For the second version of the MicroBot the robot’s outer diameter was reduced from 23 mm to 16 mm by complete redesign with a high grade of integration and using robot joints made from stainless steel for improved structural stability. Actuation changed to high power density brushed motors DCX10L with gearhead GPX10 1024:1 (Maxon Motor AG, Sachseln, Switzerland). Different from
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the first RP-prototype, this second version does not include any cabling between modules, which also allows a quick and easy re-configuration of the robot kinematic structure. The realised prototype includes four DoF in a pitch – yaw – roll – grasper configuration (Figure 3b). For both MicroBot versions the ZigBee network protocol is used for wireless communication. ZigBee is a mature, low-cost, low-power wireless networking technology that ensures encryption, low latency, and the ability to configure networks dynamically with multiple network nodes, thus being a natural choice for this application. Each robot DoF is a single node and includes a custom circular PCB designed with a Texas Instruments CC2530 microcontroller, MPC17C724 full H-bridge motor controller (Freescale Semiconductor Inc., Austin, TX, USA) and 2.4 GHz chip antenna (Molex, Lisle, IL, USA). The PCB diameter is 14 mm and is well accommodated within the 23 mm (version 1) and the 16 mm (version 2) diameter body of the MicroBot.
Master control station (MCS) The master control station (MCS) is the central software running on a standalone PC that coordinates gross and fine positioning modules, interfaces with user input devices and provides device and status updates. Communication with the KUKA LWR module is achieved through a FRI link over Ethernet. A USB-based ZigBee transceiver, CC2531 USB Dongle (Texas Instruments, Dallas, TX, USA), enables the MCS to communicate with each ZigBee node within the MicroBot. An embedded algorithm was developed using IAR Workbench (IAR Systems AB, Uppsala, Sweden) and implemented on each node to communicate with the MCS and generate pulse width modulated (PWM) signals to actuate the commanded motor. A ZigBee node initialization sequence is initiated when the MicroBot is powered on. This initialization stage assigns unique node addresses to each joint of the MicroBot. Motor actuation commands are generated by the MCS and broadcast over the ZigBee network. Each node listens to broadcast messages, discarding those where addresses do not match. When a node receives a message addressed to it, successful interpretation results in an acknowledgement packet broadcast on the ZigBee network. Thus, the MCS provides status updates and verification if a data packet was sent successfully. Building on this framework, future implementations can encapsulate motor information such as encoder position, or allow haptic feedback.
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B. Azizi Koutenaei et al.
Figure 4. KUKA LWR with mounted MAGS module. Laparoscopic video camera is used to visualize in vivo R-NOTES MicroBot (camera view is shown in the middle of the figure).
the MicroBot. A laparoscopic view of the in-vivo module anchored to the abdominal wall is shown in Figure 4. MicroBot movements were observed to mimic MAGS module movements, thus confirming the ability to grossly position the MicroBot inside the body based on KUKA LWR positioning. Gross position adjustments were made until the MicroBot module was located above the liver. To test fine positioning control, user input mapping was toggled to PWM mode within the MCS, thus locking the position of the KUKA LWR and allowing the same 3D mouse input device to be used to control MicroBot actuation. Wireless communication capabilities were tested by actuating each MicroBot node and grasping tissue. Using the laparoscopic camera, it was visually verified that user input was mapped correctly to MicroBot actuation.
Results
Conclusion
In preparation for animal studies, several laboratory assessments and a study in the operating room environment were conducted to assess the reliability and stability of the ZigBee network in a clinical scenario. Two swine studies were then completed to test end-to-end procedure capabilities of the integrated R-NOTES system. The studies were approved by the Children’s Institutional Animal Care and Use Committee. The first test was designed to demonstrate the feasibility of the MAGS and the workspace capability of the KUKA robot to provide gross positioning. The second animal study was to assess the procedural efficacy of the integrated system. An incision was made in the lower abdomen and a hand port (Endopath Dextrus, Ethicon Inc., Somerville, NJ, USA) was placed at the incision site. The hand port was used to enable insertion and retraction of the MicroBot module. The wired version of the MicroBot shown in Figure 3a was used for this study (Figure 3b). The wires provided power alone, with communication done over the ZigBee network. The longer procedure times and multiple trials necessitated the use of a wired module. The MAGS served as an end-effector on the KUKA LWR. The KUKA LWR was maneuvered into position using a 3D navigator mouse until the MAGS module was directly above the swine abdomen (Figure 4). The MAGS module was lowered onto the abdomen and engaged with the MicroBot through the abdominal wall. Using the 3D mouse, the user was able to move the KUKA LWR-MAGS module along craniocaudal and mediolateral axes. A laparoscopic camera, inserted through a side incision, provided visual feedback on the position and movement of
This paper first reviewed related literature and then described our implementation of a teleoperated, integrated robotic NOTES system. We have described the overall system architecture, device implementation, and animal studies. In a cluttered clinical environment with many potential sources of electromagnetic interference, we did not find the wireless ZigBee communication network to be constrained. Future refinement of these systems and concepts may lead to new approaches for robotic NOTES. Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. References 1. Dudrick SJ. Overview of general surgery training in the usa: History and present. Pol J Surg. 2010;82:377–402. 2. Luketich JD, Alvelo-Rivera M, Buenaventura PO, Christie NA, McCaughan JS, Litle VR, et al. Minimally invasive esophagectomy: outcomes in 222 patients. Ann Surg. 2003;238:486. 3. Autorino R, Zargar H, Kaouk JH. Robotic-assisted laparoscopic surgery: recent advances in urology. Fertil Steril. 2014; 102:S0015–282. 4. Hannaford B, Rosen J, Friedman DW, King H, Roan P, Cheng L, et al. Raven-II: an open platform for surgical robotics research. IEEE Trans Biomed Eng. 2013;60:954–9. 5. ASGE/SAGES working group on natural orifice transluminal endoscopic surgery white paper. Gastrointest Endosc. 2006; 63:199–203. 6. Ko CW, Kalloo AN. Per-oral transgastric abdominal surgery. Chin J Dig Dis. 2006;7:67–70. 7. Rao GV, Reddy DN. Transgastric appendectomy in humans. Presented at: World Congress of Gastroenterology; Montreal, Canada; September 2006.
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