Tobias Ortmaier

Mechatronic Design of a New Robot for Force Control in Minimally Invasive Surgery

Minimally invasive surgery (MIS) challenges the surgeons skills due to his/her separation from the operation area, which can be reached with long instruments only. Therefore, the surgeon looses access to the manipulation forces inside the patient. This reduces his/her dexterity when performing the operation. A new compact and lightweight robot for MIS is presented, which allows for the measurement of manipulation forces. The main advantage of this concept is that no miniaturized force sensor has to be integrated into surgical instruments and inserted into the patient. Rather, outside the patient, a standard sensor is attached to a modified trocar, which allows for the undisturbed measurement of manipulation forces. This approach reduces costs and sterilizability demands. Results of in vitro and in vivo force control experiments are presented to validate the concepts

Teleoperation concepts in minimal invasive surgery

Abstract In this paper, a teleoperating system for minimal invasive surgery is discussed. The focus lies on different control laws for the force feedback loop in telesurgery scenarios and the comparison of them. Suitable control schemes for position and force controlled minimal invasive medical robots combined with a force feedback input device without necessarily sensing the operators forces are presented. The control is extended with control parameter adaption in the force feedback control law with the estimation of the environment stiffness.

A hands-on-robot for accurate placement of pedicle screws

This paper presents a novel system for accurate placement of pedicle screws. The system consists of a new light-weight (<10 kg), kinematically redundant, and fully torque controlled robot. Additionally, the pose of the robot tool-center point is tracked by an optical navigation system, serving as an external reference source. Therefore, it is possible to measure and to compensate deviations between the intraoperative and the preoperatively planned pose. The robotic arm itself is impedance controlled. This allows for a new intuitive man-machine-interface as the joint units are equipped with torque sensors: the robot can be moved just by pulling/pushing its structure. The surgeon has full control of the robot at every step of the intervention. The hand-eye-coordination problems known from manual pedicle screw placement can be omitted

Tracking local motion on the beating heart

Local motion on the beating heart is investigated in the context of minimally invasive robotic surgery. The focus lies on the motion remaining in the mechanically stabilised field of surgery of the heart. Motion is detected by tracking natural landmarks on the heart surface in 2D video images. An appropriate motion model is presented with a discussion of its degrees of freedom and a trajectory analysis of its parameters.

A Force Controlled Laparoscopic Surgical Robot without Distal Force Sensing

As robot applications in humane nvironments increase, we see many interesting application in medicine. Thesei nclude robotic technologies used in robot-doctor interfaces for minimally invasive surgery and novel roboticdevices that can navigatei nsideh umanbodies.This chapter presents 3 interestingarticles representing the various facets of medical robotics.Papers in other chapters, however,alsodescribemedicalapplications of robotics. The first article by Zemetiand co-workers presents the designand analysis of a Minimally InvasiveSurgery robot.The trocar is designed withforcemeasurement capability, where the force sensor is placed outside the patient – to reducecost and sterilizibility requirements . This paper presents the results of the feasibility experiments. In the next article,D ario and colleagues take medical robotics a step further into the futureby reportingo n the concept and the preliminary modelingo fl egged micro robot locomoting in a tubular, slippery and compliant environment.The intendedapplication is for the microrobots ton avigatei nside the gastrointestinal tract for diagnosis and therapy.The microcapsules ared esigned tobei ngestible and then tomake its way to the gastrointestinal tract.The new contributionbeing studied herei s the micro robots capability of effectivel ocomotion while inside the humanbody. The thirdarticle by Casals, et al .p resents amultimodalapproach toh uman-machine interface,a pplied t om edical robotics.This carries a similar idea to the first article in Chapter XIIIb y Iba et al , under the heading of Haptics and Augmented Reality.The ideais top rovide a rangeo fm ediaof communication between the surgeonand the robots, thus creating aquasi-hands-free control of the equipments.This would allow the surgeon tobetter control the equipments in the operating room without losing too muchf ocus on the taskat hand. The mode of interactionbeing studiedi s gesture recognition, witho ther modes available such as: tactile, speech,pedals,etc. Abstract. Minimally invasive surgery (MIS) challenges the surgeons skills due to his separation from the operation area which can be reached with long instruments only. Therefore, the surgeon loses access to the manipulation forces inside the patient. This reduces his dexterity when performing the operation. A new compact and lightweight robot for MIS is presented which allows for the measurement of manipulation forces. The main advantage of this concept is that no miniaturized force sensor has to be integrated into surgical instruments and inserted into the patient. Rather, a standard sensor is attached to a modified trocar outside the patient, which allows for the measurement of manipulation forces. This approach reduces costs and sterilizability demands. Results of first force control experiments are presented to show the feasibility of the concepts.

A new robot for force control in minimally invasive surgery

Minimally invasive surgery (MIS) challenges the surgeons skills due to his separation from the operation area, which can be reached with long instruments only. Therefore, the surgeon loses access to the manipulation forces inside the patient. This reduces his dexterity when performing the operation. A new compact and lightweight robot for MIS is presented which allows for the measurement of manipulation forces. The main advantage of this concept is that no miniaturized force sensor has to be integrated into surgical instruments and inserted into the patient. Rather, outside the patient a standard sensor is attached to a modified trocar, which allows for the undisturbed measurement of manipulation forces. This approach reduces costs and sterilizability demands. Results of first force control experiments are presented to show the feasibility of the concepts.

Automatic Guidance of a Surgical Instrument with Ultrasound Based Visual Servoing

Visual servoing is a possible solution to assist the surgeon in performing tasks under ultrasound (US) imaging. To this aim, a system was developed that allows the surgeon to select a desired instrument location on a US image. Then a robot is programmed to automatically move the instrument towards the selected location. This approach requires robust tracking of the instrument in the US image, together with modeling of the overall system and implementation of a visual servoing loop. This paper presents geometrical and kinematic models of the system, as well as the control loop design, which is validated through both numerical simulations, and results of in vitro experiments.

The DLR MiroSurge - A robotic system for surgery

This video presents the in-house developed DLR MiroSurge robotic system for surgery. As shown, the system is suitable for both minimally invasive and open surgery. Essential part of the system is the MIRO robot: The soft robotics feature enables intuitive interaction with the robot.

Robot Assisted Force Feedback Surgery

Minimally invasive surgery characterizes a sophisticated operation technique in which long, slender instruments are inserted into the patient through small incisions. Though providing crucial benefits compared to open surgery (i.e. reduced tissue traumatization) it is also faced with a number of disadvantages. One of the major problems is that the surgeon cannot access the operating field directly and, therefore, can neither palpate tissue nor sense forces sufficiently. Furthermore, the dexterity of the surgeon is reduced as the instruments have to be pivoted around an invariant point.

Manipulability and Accuracy Measures for a Medical Robot in Minimally Invasive Surgery

This paper presents measures for manipulability and accuracy that are specifically adapted to the conditions found in robotically assisted minimally invasive surgery. The considered robot consists of 9 active joints, thus allowing for full manipulability at the tool tip as well as null-space motion. The presented manipulability and positioning accuracy measures are based on an “inverse Jacobian” approach since the constraints at the entry point into the human body forbid a classic formulation. High significance of the measures is reached by including robot design parameters such as encoder resolution and maximum joint velocity.