IECON 2012 - Robotic System for Single Incision Laparoscopic Surgery
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This paper proposes a robotic system to assist and collaborate with surgeons in Single Incision Laparoscopic Surgery (SILS) operations. The system, aim at solving the main drawbacks of this kind of surgery, is composed of a miniature camera robot and a redundant robotic grasper. Positioning of both robots inside the patient’s abdomen is done by means of magnetic control. External magnetic sources are placed at the end effector of two robotic arms, and permanent magnets are integrated in the robots. Camera robot is provided with three permanent magnets, so both position and orientation can be controlled. Sliding control, which is robust against perturbations and parameter uncertainties, is chosen. Robotic grasper’s redundancy makes possible autonomously obstacle avoidance and increases its workspace. The haptic device is designed so as surgeons can handle the grasper as if it were a conventional tool. In order to this aim, augmented reality is used to simulate a traditional tool in the visual feedback system, in substitution of the robotic grasper. Besides the telemanipulation, requirements for autonomously functions to assist surgeons in the specific tasks of suturing are discussed.
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IECON 2012 - Robotic System for Single Incision Laparoscopic Surgery
- 1. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines Irene Rivas Blanco P. del Saz-Orozco, I. Garcia-Morales, V. Muñoz Department of System Engineering and Automation University of Málaga (Spain) ROBOTIC SYSTEM FOR SINGLEROBOTIC SYSTEM FOR SINGLE INCISION LAPAROSCOPIC SURGERYINCISION LAPAROSCOPIC SURGERY
- 2. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines I. INTRODUCTION II. CAMERA ROBOT III. REDUNDANT ROBOTIC GRASPER IV. CONCLUSIONS & FUTURE WORK INDEX
- 3. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines I. INTRODUCTIONI. INTRODUCTION
- 4. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines I. INTRODUCTION • Single Incision Laparoscopic Surgery (SILS) Loss of triangulation between camera and instruments Limitation of the range of motion of instruments outside the abdomen
- 5. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines(HMM) (HMM) I. INTRODUCTION Camera robot Magnetic source Magnetic source Robotic grasper Haptic • System approach
- 6. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines II. CAMERA ROBOTII. CAMERA ROBOT
- 7. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines II. CAMERA ROBOT net Miniature robot Robotic arm Patient’s skin 3cm • 3V small size batteries • Xbee module (wireless connectivity) • Inclinometer Camera Magnets LL1 L2 LED • Robot design
- 8. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines Өd Geometric model + - Right Magnet Controller Left Magnet Controller L2 L1 II. CAMERA ROBOT • Global control scheme InclinometerӨ Geometric model PID
- 9. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines II. CAMERA ROBOT • Single Magnet Control xd Sliding mode control u Working point estimation and linearization K State Observer Hall effect sensor i x, v Electromagnet
- 10. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines II. CAMERA ROBOT • Simulations ‐ First simulation: validate the sliding mode control strategy Check the robustness of the system against parameter uncertainties time (s) time (s) distance(m) CHANGE IN MASS CHANGE IN MAGNETIC CONSTANT distance(m)
- 11. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines II. CAMERA ROBOT • Simulations ‐ Second simulation: validate the global control scheme Check the system response to an inclination setpoint time (s) time (s) distance(m) ROBOT INCLINATION MAGNETS DISTANCE distance(m) time (s) angle(grades)
- 12. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines III. REDUNDANT ROBOTICIII. REDUNDANT ROBOTIC GRASPERGRASPER
- 13. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines III. ROBOTIC REDUNDANT GRASPER Base frame Tool frame REDUNDANT KINEMATICS Abdomen EXTERIOR WORKSPACE INTERIOR WORKSPACE 520mm • Grasper design
- 14. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines ‐ Robotic grasper does not move as a conventional one ‐ Augmented reality to simulate a conventional surgical tool Virtual tool Surgical tool Robotic grasper • Master Console III. ROBOTIC REDUNDANT GRASPER
- 15. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines • Autonomous collaboration ‐ Suture: difficult and time‐consuming task ‐ Rosser method: uses a primary tool (surgeon) and a visupport tool (robot) Primary tool Support tool STATE DIAGRAM III. ROBOTIC REDUNDANT GRASPER
- 16. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines • Sensory Systems and Interfaces III. ROBOTIC REDUNDANT GRASPER Voice recognition systemSurgeon Maneuver recognition system Tracker 3D Force sensor systemForce sensor Camera Vision system
- 17. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines IV. CONCLUSIONS &IV. CONCLUSIONS & FUTURE WORKFUTURE WORK
- 18. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines IV. CONCLUSIONS ‐ Robotic system aimed at solving the main drawbacks of Single Incision Laparoscopic Surgery: ‐ Loss of triangulation (camera robot) ‐ Reduction of the range of motion (robotic grasper) ‐ Experiments with a first prototype of camera robot ‐ Dynamics analysis of robotic grasper ‐ Development of first prototype of robotic grasper • Conclusions • Future Work
- 19. DepartmentofSysyem EngineeeringandAutomation Víctor F. Muñoz Martínez Research lines THANK YOU FOR YOURTHANK YOU FOR YOUR ATTENTIONATTENTION
Editor's Notes
- Thank you for the presentation. As the chairman said, my name is Irene Rivas and I belong to the engineering group of medical robotics of the university of Málaga. I’m going to present a paper dealing with a robotic system composed of a miniature camera robot and a redundant robotic grasper. The system is aimed at solving the main problems of single incision laparoscopic surgeries.
- First of all I’m going to describe the system proposed, which is composed of a camera robot and a robotic grasper. Afterwards, I will describe the camera robot design and its control strategy, (and I will present a set of Matlab simulations to validate the proposal ). After that I will describe the robotic grasper design and I will propose an autonomous control to collaborate with the surgeon in a specific task. I will finish with the conclusions and the future work.
- I’m going to start with the system approach.
- Unlike open surgery, minimally invasive procedures are performed through small incisions on the abdominal wall, whereby the surgical tools and the laparoscope are introduced. Among these techniques, single incision laparoscopic procedures are aimed at reducing the number of incisions to one, so all surgical instruments and the camera are introduced through the same incision. Despite its many advantages, this method has two main drawbacks. Inside the abdomen, close proximity of the instruments and the laparoscope entails a loss of triangulation, which implies a lack of depth sensation. And outside the abdomen, close proximity of the instruments entails a limitation of their range of motion. The robotic system proposed in this paper is aimed at solving these two problems.
- The system proposed is composed of a camera robot and a robotic grasper. Both robots are introduced into the abdomen through the single port and they are attached to the abdominal wall through magnetic interaction. Magnetic sources are placed at the end effector of two external robotic arms, so internal robots can be moved inside the abdomen by moving the external robots. Orientation of the camera is also controlled by magnetic field. This way, the need of motors to orientate the camera is avoided. As communication is done wireless, there is no need of wires for the robotic camera. On the other hand, robotic grasper is controlled by teleoperation through a haptic, which is placed apart from the entry port, so surgeon can operate as if it were a conventional multiport operation. Besides teleoperation, implementation of some autonomous tasks is proposed, so as the robot can collaborate with the surgeon in a specific task. So, what are the advantages of this system? On one hand, loss of triangulation is avoided as we have move the camera apart from the surgical instruments. On the other hand, the problem of the limitation in the range of motion of the instruments is avoided as we have move the haptic that controls the robotic grasper away from the entry port.
- Next I’m going to describe the camera robot
- Camera robot design is depicted in this picture. The robot is composed of three magnets to control its orientation, an illumination system, and a camera. Three small 3 volts batteries are used as power supply, and communication is done with an xbee wireless module. An inclinometer is used to measure the actual inclination of the robot. The picture in the right shows how the orientation of the robot is controlled. The magnetic source is composed of three electromagnets. Maintaining fixed the distance between the central magnet and the magnetic source, orientation is varied by varying the distance of the distal magnets. So, varying the current of the distal electromagnets, we can vary the values of the distances L1 and L2, and therefore the inclination of the robot.
- This picture shows the global scheme of the system, where theta represents the inclination of the robot. This inclination is transformed into the corresponding distances between the magnets inside the robot and the magnetic source through a geometric model, which is depicted below. The controller of both right and left magnet controls the current needed in the electromagets to obtain the desired distance. The feedback of the system is done with an inclinometer, which provides the actual orientation of the robot. The work presented in this paper is focused on the control of a single magnet
- The control scheme of a single magnet is shown in this picture. The aim of this control is to apply the necessary voltage to the electromagnet to obtained the desired distance xd. Sliding mode has been chosen as the control strategy because the electromagnet dynamics is a non-linear system, and it has parameter uncertainties. The feedback is done with a state observer due to the fact that not all variables of the electromagnet dynamics are measureable. Current can be measure with a hall effect sensor, but distance and velocity will be observed. As we are working with a non–linear system, it has to be linearized to be able to use the state observer. So the system will be linearized by online estimation of the working point. Once we have linearized the system, the parameters of the observer are calculated. The outputs of the state observer are the distance between the electromagnet and the magnet inside the robot, and the velocity.
- Two simulations have been carried out to validate the proposal. The first one is done to validate the control of a single magnet, and the second one to validate the global control scheme. So, the aim of this first simulation is to validate the sliding mode control strategy by checking the robustness of the system against parameter uncertainties. The figure in the left shows the system response against a change in mass. When all electromagnets are working properly each one has to support a third part of the total mass, that is, 50 grams. But in case of a magnet failure, each electromagnet will have to control the half of the mass. The figure in the right shows the system response against a change in the magnetic constant value. Magnetic constant can vary up to a 30% due to the variability of each patient characteristic, as the patient abdomen is between the magnetic source and the robot. As we can see the control proposed make the system robust against changes in both values
- The second experiment is aimed at validating the global control scheme. To this purpose, a 15 degrees inclination setpoint has been established. The figure in the left shows how the system reaches the desired inclination, and the figure in the right shows the corresponding right and left magnets distance to reach the desired inclination.
- Next I’m going to describe the redundant robotic grasper.
- Robotic grasper has been designed with a redundant structure of 7 degrees of freedom to both increase its workspace and to have the possibility of avoiding obstacles inside the abdomen, as other surgical tools or patient’s organs. The total length of the grasper is 5 cm so as the exterior workspace covers the whole abdominal cavity, simulated as a parallelepiped. With respect to the internal workspace, challenging locations to reach are those that are close to the robot’s base, which are not reachable with a non-redundant structure. As it can be seen in the below figure, the grasper is capable to reach any location around the first link. One of the main challenges in developing such a grasper robot is the election of the actuators, which have to be small enough to not increase the grasper size, and must withstand high enough torques to be able to develop surgical tasks. So a tradeoff solution between actuators volume and output torque must be achieved.
- Robotic grasper is handled by teleoperation. Master console is design so as surgeons can handle the haptic as if it were a conventional tool, and the master structure will transform these movements into an appropriate configuration of the grasper. This way, a training phase to get skilled with this grasper is avoided. Moreover, as I said before, the grasper haptic is moved apart from the entry port and so from others surgical tools, making the operation as similar as possible to a conventional multiport one. On the other hand, images provided by the camera are essential for surgeons to operate in a laparoscopic procedure, as they are the only visual feedback they have. In this sense, the presence of the robotic grasper in the scene may disturb surgeons as they are not used to it. The use of augmented reality to substitute the robotic grasper by a virtual conventional tool can avoid this problem.
- As I said before, besides the teleoperation control, a set of autonomous tasks will be implemented so as the grasper can collaborate with the surgeon during a specific surgical task. Suturing is one of the most challenging surgical tasks and takes a significant percentage of the operating time. So automating suture procedure would reduce the surgery durations and decrease the demand on surgeons during this task. Among the different suturing methods, Rosser method has been chosen as actions are clearly differentiate between a primary tool, which will be the one handled by the surgeon, and a support tool, which will be the robotic grasper. As it can be seen in the state diagram of suturing, the overall task can be divided into 5 subtasks: stitching, first knotting, second knotting, third knotting, and finally thread cutting. Each subtask can also be divided into a set of basic actions. The analysis of transitions between tasks and subtasks reveals the need of four sensory system to be able to develop an autonomous suturing.
- So, to automate suturing these four sensory systems are needed. A voice recognition system enables the surgeon to interact with the system at any moment by means of voice commands. A manuevuer recognition system makes the system capable to recognizes the specific maneuver the surgeon is performing, and so identify in which state the procedure is. A force sensory system will be integrated at the tip of the robotic grasper to detect pressure on the tissue. And finally, images transmitted by the camera will be analyzed in the vision system by means of appropriate vision algorithms capable of identifying the different elements of the scene.
- I’m going to finish the presentation with the conclusions and the future work.
- Summarizing, a robotic system aimed at solving the main drawbacks of single incision laparoscopic surgery has been presented. On one hand, the loss of triangulation is avoided thanks to a camera robot which is inserted into the abdomen and move apart from the surgical tools. Moreover, this solution reduces the number of instruments sharing the entry port, letting more space for an additional tool. On the other hand, the use of a robotic grasper avoids the problem of the limitation in the range of motion, as it is teleoperated with a haptic which is moved away from the other instruments. Moreover, an autonomous collaboration in the task of suturing has been proposed. As future work, experiments with a first prototype of the camera robot will be developed, which is actually under development. Related to the grasper, in this work both the kinematics and the actuators election has been analyzed, so the next step will be a dynamics analysis to determine the maximum force the grasper is able to develop. Afterwards, a first prototype will be develop.