Haptics-Enabled Teleoperation for Robotics-Assisted Minimally Invasive Surgery

The lack of force feedback (haptics) in robotic surgery can be considered to be a safety risk leading to accidental tissue damage and puncturing of blood vessels due to excessive forces being applied to tissue and vessels or causing inefficient control over the instruments because of insufficient applied force. This project focuses on providing a satisfactory solution for introducing haptic feedback in robotics-assisted minimally invasive surgical (RAMIS) systems. The research addresses several key issues associated with the incorporation of haptics in a master-slave (teleoperated) robotic environment for minimally invasive surgery (MIS). In this project, we designed a haptics-enabled dual-arm (two masters - two slaves) robotic MIS testbed to investigate and validate various single-arm as well as dual-arm teleoperation scenarios. The most important feature of this setup is the capability of providing haptic feedback in all 7 degrees of freedom (DOF) required for RAMIS (3 translations, 3 rotations and pinch motion of the laparoscopic tool). The setup also enables the evaluation of the effect of replacing haptic feedback by other sensory cues such as visual representation of haptic information (sensory substitution) and the hypothesis that surgical outcomes may be improved by substituting or augmenting haptic feedback by such sensory cues

Multimodal Noncontact Tracking of Surgical Instruments

For many procedures, open surgery is being replaced with minimally invasive surgical (MIS) techniques. The advantages of MIS include reduced operative trauma and fewer complications leading to faster patient recovery, better cosmetic results and shorter hospital stays. As the demand for MIS procedures increases, effective surgical training tools must be developed to improve procedure efficiency and patient safety. Motion tracking of laparoscopic instruments can provide objective skills assessment for novices and experienced users. The most common approaches to noncontact motion capture are optical and electromagnetic (EM) tracking systems, though each approach has operational limitations. Optical trackers are prone to occlusion and the performance of EM trackers degrades in the presence of magnetic and ferromagnetic material. The cost of these systems also limits their availability for surgical training and clinical environments. This thesis describes the development and validation of a novel, noncontact laparoscopic tracking system as an inexpensive alternative to current technology. This system is based on the fusion of inertial, magnetic and distance sensing to generate real-time, 6-DOF pose data. Orientation is estimated using a Kalman-filtered attitude-heading reference system (AHRS) and restricted motion at the trocar provides a datum from which position information can be recovered. The Inertial and Range-Enhanced Surgical (IRES) Tracker was prototyped, then validated using a MIS training box and by comparison to an EM tracking system. Results of IRES tracker testing showed similar performance to an EM tracker with position error as low as 1.25 mm RMS and orientation error \u3c0.58 degrees RMS along each axis. The IRES tracker also displayed greater precision and superior magnetic interference rejection capabilities. At a fraction of the cost of current laparoscopic tracking methods, the IRES tracking system would provide an excellent alternative for use in surgical training and skills assessment

Modeling of Force and Motion Transmission in Tendon-Driven Surgical Robots

Tendon-based transmission is a common approach for transferring motion and forces in surgical robots. In spite of design simplicity and compactness that comes with the tendon drives, there exists a number of issues associated with the tendon-based transmission. In particular, the elasticity of the tendons and the frictional interaction between the tendon and the routing result in substantially nonlinear behavior. Also, in surgical applications, the distal joints of the robot and instruments cannot be sensorized in most cases due to technical limitations. Therefore, direct measurement of forces and use of feedback motion/force control for compensation of uncertainties in tendon-based motion and force transmission are not possible. However, force/motion estimation and control in tendon-based robots are important in view of the need for haptic feedback in robotic surgery and growing interest in automatizing common surgical tasks. One possible solution to the above-described problem is the development of mathematical models for tendon-based force and motion transmission that can be used for estimation and control purposes. This thesis provides analysis of force and motion transmission in tendon-pulley based surgical robots and addresses various aspects of the transmission modeling problem. Due to similarities between the quasi-static hysteretic behavior of a tendon-pulley based da Vinci® instrument and that of a typical tendon-sheath mechanism, a distributed friction approach for modeling the force transmission in the instrument is developed. The approach is extended to derive a formula for the apparent stiffness of the instrument. Consequently, a method is developed that uses the formula for apparent stiffness of the instrument to determine the stiffness distribution of the tissue palpated. The force transmission hysteresis is further investigated from a phenomenological point of view. It is shown that a classic Preisach hysteresis model can accurately describe the quasi-static input-output force transmission behavior of the da Vinci® instrument. Also, in order to describe the distributed friction effect in tendon-pulley mechanisms, the creep theory from belt mechanics is adopted for the robotic applications. As a result, a novel motion transmission model is suggested for tendon-pulley mechanisms. The developed model is of pseudo-kinematic type as it relates the output displacement to both the input displacement and the input force. The model is subsequently used for position control of the tip of the instrument. Furthermore, the proposed pseudo-kinematic model is extended to compensate for the coupled-hysteresis effect in a multi-DOF motion. A dynamic transmission model is also suggested that describes system’s response to high frequency inputs. Finally, the proposed motion transmission model was used for modeling of the backlash-like hysteresis in RAVEN II surgical robot

Assistance strategies for robotized laparoscopy

Robotizing laparoscopic surgery not only allows achieving better accuracy to operate when a scale factor is applied between master and slave or thanks to the use of tools with 3 DoF, which cannot be used in conventional manual surgery, but also due to additional informatic support. Relying on computer assistance different strategies that facilitate the task of the surgeon can be incorporated, either in the form of autonomous navigation or cooperative guidance, providing sensory or visual feedback, or introducing certain limitations of movements. This paper describes different ways of assistance aimed at improving the work capacity of the surgeon and achieving more safety for the patient, and the results obtained with the prototype developed at UPC.Peer ReviewedPostprint (author's final draft

Development of a Novel Handheld Device for Active Compensation of Physiological Tremor

In microsurgery, the human hand imposes certain limitations in accurately positioning the tip of a device such as scalpel. Any errors in the motion of the hand make microsurgical procedures difficult and involuntary motions such as hand tremors can make some procedures significantly difficult to perform. This is particularly true in the case of vitreoretinal microsurgery. The most familiar source of involuntary motion is physiological tremor. Real-time compensation of tremor is, therefore, necessary to assist surgeons to precisely position and manipulate the tool-tip to accurately perform a microsurgery. In this thesis, a novel handheld device (AID) is described for compensation of physiological tremor in the hand. MEMS-based accelerometers and gyroscopes have been used for sensing the motion of the hand in six degrees of freedom (DOF). An augmented state complementary Kalman filter is used to calculate 2 DOF orientation. An adaptive filtering algorithm, band-limited Multiple Fourier linear combiner (BMFLC), is used to calculate the tremor component in the hand in real-time. Ionic Polymer Metallic Composites (IPMCs) have been used as actuators for deflecting the tool-tip to compensate for the tremor

A comprehensive review of haptic feedback in minimally invasive robotic liver surgery: Advancements and challenges

Background: Liver medical procedures are considered one of the most challenging because of the liver's complex geometry, heterogeneity, mechanical properties, and movement due to respiration. Haptic features integrated into needle insertion systems and other medical devices could support physicians but are uncommon. Additional training time and safety concerns make it difficult to implement in robot-assisted surgery. The main challenges of any haptic device in a teleoperated system are the stability and transparency levels required to develop a safe and efficient system that suits the physician's needs. Purpose: The objective of the review article is to investigate whether haptic-based teleoperation potentially improves the efficiency and safety of liver needle insertion procedures compared with insertion without haptic feedback. In addition, it looks into haptic technology that can be integrated into simulators to train novice physicians in liver procedures. Methods: This review presents the physician's needs during liver interventions and the consequent requirements of haptic features to help the physician. This paper provides an overview of the different aspects of a teleoperation system in various applications, especially in the medical field. It finally presents the state-of-the-art haptic technology in robot-assisted procedures for the liver. This includes 3D virtual models of the liver and force measurement techniques used in haptic rendering to estimate the real-time position of the surgical instrument relative to the liver. Results: Haptic feedback technology can be used to navigate the surgical tool through the desired trajectory to reach the target accurately and avoid critical regions. It also helps distinguish between various textures of liver tissue. Conclusion: Haptic feedback can complement the physician's experience to compensate for the lack of real-time imaging during Computed Tomography guided (CT-guided) liver procedures. Consequently, it helps the physician mitigate the destruction of healthy tissues and takes less time to reach the target.</p

Body Wall Force Sensor for Simulated Minimally Invasive Surgery: Application to Fetal Surgery

Surgical interventions are increasingly executed minimal invasively. Surgeons insert instruments through tiny incisions in the body and pivot slender instruments to treat organs or tissue below the surface. While a blessing for patients, surgeons need to pay extra attention to overcome the fulcrum effect, reduced haptic feedback and deal with lost hand-eye coordination. The mental load makes it difficult to pay sufficient attention to the forces that are exerted on the body wall. In delicate procedures such as fetal surgery, this might be problematic as irreparable damage could cause premature delivery. As a first attempt to quantify the interaction forces applied on the patient's body wall, a novel 6 degrees of freedom force sensor was developed for an ex-vivo set up. The performance of the sensor was characterised. User experiments were conducted by 3 clinicians on a set up simulating a fetal surgical intervention. During these simulated interventions, the interaction forces were recorded and analysed when a normal instrument was employed. These results were compared with a session where a flexible instrument under haptic guidance was used. The conducted experiments resulted in interesting insights in the interaction forces and stresses that develop during such difficult surgical intervention. The results also implicated that haptic guidance schemes and the use of flexible instruments rather than rigid ones could have a significant impact on the stresses that occur at the body wall

A Novel Minimally Invasive Tumour Localization Device

Lung cancer is one of the leading causes of death, by cancer. The usual treatment is surgical resection of tumours. However, patients who are weak or have poor pulmonary function are deemed unfit for surgery. For these patients, a minimally-invasive approach is desired. A major problem associated with minimally-invasive approaches is tumour localization in real time and accurate measurement of tool--tissue forces. This thesis describes the design, analysis, manufacturing and validation of a minimally-invasive instrument for tumour localization, named Palpatron. The instrument has an end effector that is able to support two previously designed jaws, one containing an ultrasound sensor and the other a tactile sensor. The jaws can move with two degrees of freedom to palpate tissue and rotate about the central axis of the instrument. The Palpatron has uncoupled jaw motion that allows for optimal alignment of sensors to improve data acquisition. The instrument can be easily assembled and disassembled allowing it to be cleaned and sterilized. The mechanism is articulated using push rods, each actuated by a motor. A semi-automatic control system was created for palpation. It is composed of a microcontroller that controls four motors via serial communication. In addition, the Palpatron has the ability to prevent tissue damage by measuring tool--tissue forces. Finite element analysis was used to guide material selection for designed components. Grade 5 titanium was selected for end effector links to provide a factor of safety of 1.2 against yielding under a 10 N point load at the tip of a jaw. The design was fabricated and validated by conducting experiments to test articulation and load carrying capacity. An 8-N force was applied to the instrument, which was successfully supported. The semi-automatic control system was used to perform basic maneuvering tasks to verify jaw motion capabilities. With positive testing results, the Palpatron forms the next step towards a comprehensive robotic-assisted palpation technology