COMPASS: localization in laparoscopic visceral surgery

In recent years, the remote center of motion (RCM) constraint has moved from purely mechanical to software implementation, enabling the use of serial manipulators in robotic‐assisted minimal invasive surgery. However, ensuring safety with software‐based RCM presents challenges. This article addresses this issue by introducing a novel control algorithm for a 7‐DOF redundant robotic arm, taking into account a software RCM while considering system passivity and kinematic constraints. The algorithm is both a control optimizer and a robot kinematics inversion, enabling precise and dexterous control for various surgical tasks and other control applications. By formulating a quadratic optimization problem under linear constraints, the algorithm guarantees the robotic arm's performance, safety, and stability under communication delay. Experimental validation demonstrates the effectiveness and accuracy of the control algorithm in executing a surgical training task (peg‐and‐ring) during bilateral teleoperation. The results highlight the successful implementation of the RCM constraint, ensuring patient safety and optimizing the manipulation capabilities of the robotic arm.

Remote center of motion (RCM) mechanisms are widely utilized to achieve minimally invasive surgery (MIS) instead of manual operation. To realize the translation motion in an RCM mechanism, the proximal actuation method is generally adopted, which has the disadvantages of reducing the vision field, offsetting the RCM point, and increasing the moment of inertia. This paper proposes a surgery robot with a novel RCM configuration realized by a three-rhombus mechanism. The great merit of this robot is the actuators are all mounted on the base. The kinematics and singularity of the mechanism are investigated analytically. Parameter optimization is done under the given rotation angle of 90° and feed depth of 47.8 mm, respectively. Preliminary simulations are conducted in SolidWorks environment to validate the effectiveness of the RCM mechanism.

The remote center of motion (RCM) mechanism is a prominent candidate to aid bone drilling. The surgeon can simply place a drill with the RCM mechanism near the entry point to provide drill alignment with the target. Using this assistive mechanism for bone drilling improves drilling accuracy and reduces the complexity of bone drilling robotic systems. However, because most RCM mechanisms have been developed for laparoscopic surgery or needle insertion into soft tissue, they lack rigidity and are unsuitable for bone drilling. One of the most difficult and important surgical procedures in bone drilling is maintaining as well as guiding the orientation of the drill with respect to the target. This paper proposes an improved RCM mechanism in which a pair of linear actuators and a gearless arc-guide are employed to achieve high rigidity and resolution, which enable bone drilling. A vision-guided navigation system is also integrated into the proposed system to automatically guide the orientation. To verify that the proposed RCM mechanism has sufficient rigidity and targeting accuracy, a series of experiments was performed. The results obtained confirm that the proposed mechanism can maintain its tilting angle under up to 50 N, with a targeting error of approximately 0.28mm.

A surgeon in a sterilized area can perform robotically assisted laparoscopic solo surgery while controlling a laparoscope-holding robot for view stabilization and a forceps robot for pulling organs. At present, no locally operated surgical assistant manipulator with a mechanical remote center of motion (RCM) is available to operate within a small space while providing a wide range of movement. The present study describes a new locally operated detachable end-effector manipulator (LODEM) with diagonal joints and multi-stage telescopic screws. A forceps manipulator attached to commercial surgical forceps was developed. This manipulator uses RCM diagonal joints for the yaw and pitch axes, providing an intuitive pivot point and free rotation, and telescopic nested screws with multiple sliders clamp the commercial forceps for the axis of insertion. The manipulator placed above the abdominal wall using a fixed arm connected to a bed rail is motor controlled by a handheld interface with button switches for precise traction and is controlled manually for easy rough positioning. Positional accuracy at the tip with a load of 5N was under 0.5mm. Mechanical deflection was under 2.1mm. The manually controlled force was under 4.4N. Successful simulated laparoscopic cholecystectomy using the prototype manipulator to handle the target and maintain stability was performed on a surgically realistic gallbladder model. A LODEM with diagonal joints and multi-stage telescopic screws was developed to facilitate minimally invasive, robotically assisted laparoscopic solo surgery by a surgeon working near the patient. This electric motor-controlled laparoscopic instrument holder by the surgeon in the surgical field could be used for such applications.

A robotic surgical system capable of performing minimally invasive surgery (MIS) is proposed in this paper. Based on the requirements of MIS, a compliant, seven- degrees of freedom (7-DOF) pneumatically actuated mechanism is designed. A remote center of motion (RCM) as a parallelogram mechanism for holding the laparoscopic camera is also developed. The operating workspace of robotic surgical system is determined considering the physical constraints imposed by mechanical joints. The simulation results show that the robotic system meets the design requirement. This research will lay a good foundation for the development of a compliant surgical robot to assist in MIS.

Robot-assisted minimally invasive surgery (MIS) has shown tremendous advances over the traditional techniques. To improve dexterity and back-drivability of the existing planar remote center-of-motion (RCM) mechanism, on which an active prismatic joint is required to drive the surgical tool move in–out of the patient's body, a two degrees-of-freedom (DOFs) planar RCM mechanism is proposed by constructing virtual parallelograms in this paper. The mechanism can be considered as a generalized double parallelogram; both of the actuated joints are revolute joints. This feature enhances the intrinsic back-drivability of the mechanism. The mathematical framework is introduced first to prove that the mechanism could execute RCM. Then, the inverse kinematics of the planar mechanism is solved, and the Jacobian matrix is derived in this paper. Further, the singularity and the kinematic performance based on the kinematic equations are investigated, and the workspace of the mechanism is verified. Finally, a prototype was built to test the function of the proposed RCM mechanism. The results show that the mechanism can fulfill the constraint of MIS, and it can be used as the basic element of the active manipulator in an MIS robot.

Robot-assisted technology for minimally invasive surgery (MIS) can improve the quality of surgery and help surgeons carry out surgery more easily. The remote center of motion (RCM) mechanism with multiple degrees of freedom (DoFs) is one of the key parts of the MIS robot. A linear motion unit is usually used to realize the translation of the surgical tool along its axis in existing RCM mechanisms, which occupies a large space above the patient’s body and is prone to interference. Based on the double parallelogram mechanism, an RCM mechanism is proposed, which can realize pitch and translation motion of the surgical tool. The geometrical modeling is introduced first to prove that there is a remote center of the mechanism during its movement. Then, the inverse kinematics is analyzed on the basis of geometrical modeling of the mechanism. Furthermore, the singularity, Jacobian matrix and the kinematic performance of the mechanism are analyzed, and the workspace is verified with the kinematics equation. Finally, a prototype based on the proposed RCM mechanism was built to test its function. The results indicate that the remote center motion can be realized by this mechanism, and it can be used to develop an MIS manipulator.

In this paper, a novel method is proposed to implement automatic field of view control of laparoscopes. The laparoscope is visually controlled to follow moving surgical tools under remote center of motion (RCM) constraints introduced by minimally invasive surgery (MIS). A vision-based tracking algorithm is designed for view plane and view depth control. The view plane is controlled by visually tracking point features on surgical tools. And the view depth is controlled based on distance features in the image plane. During this process, the RCM constraints on laparoscope manipulation are implemented softly. And a pose generator of the laparoscope is proposed. The effectiveness of the proposed method is validated by simulation and experiment results.

This paper presents a novel orientation estimate approach named inertial guided visual sample consensus (IGVSAC). This method is intentionally designed for capturing the orientation of human body joints in free-living environments. Unlike the traditional visual-based orientation estimation methods, where outliers among putative image-pair correspondences are removed based on hypothesize-and-verify models such as the computationally costly RANSAC, our approach novelly exploits prior motion information (i.e., rotation and translation) deduced from the quick-response inertial measurement unit (IMU) as the initial body pose to assist camera in removing hidden outliers. In addition, our IGVSAC algorithm is able to ensure estimation accuracy even in the presence of a large quantity of outliers, thanks to its capability of rejecting apparent mismatches. The estimated orientation from the visual sensor is, in turn, able to correct long-term IMU drifts. We conducted extensive experiments to verify the effectiveness and robustness of our IGVSAC algorithm. Comparisons with highly accurate VICON and OptiTrack Motion Tracking Systems prove that our orientation estimate system is quite suitable for capturing human body joints.

This paper presents a new method for 3D position and orientation estimation based on the magnetic field generated by a single coil and the fusion of low power magnetometers and inertial sensors. The fixed spatial relationship between the sensors is exploited to solve the ambiguity problem that occurs when only a single coil is employed. In this context a new positioning algorithm is developed and verified by simulations. Using a single coil instead of three coils as common in conventional magnetic field based systems brings a benefit both regarding power consumption and construction size. Moreover, as the proposed system requires no line of sight between source and sensors, it is ideally suited for portable, location-independent applications such as the mobile assessment of a persons' head to torso posture and movement e.g. for the purpose of examining causes for chronic pain in the cervical spine area under conditions of daily life.

A Drift-Free 3D Orientation and Displacement estimation method (DFOD) based on a single inertial measurement unit (IMU) is proposed and validated. Typically, body segment orientation and displacement methods rely on a constant- or zero-velocity point to correct for drift. Therefore, they are not easily applicable to more proximal segments than the foot. DFOD uses an alternative single sensor drift reduction strategy based on the quasi-cyclical nature of many human movements. DFOD assumes that the quasi-cyclical movement occurs in a quasi-2D plane and with an approximately constant cycle average velocity. DFOD is independent of a constant- or zero-velocity point, a biomechanical model, Kalman filtering or a magnetometer. DFOD reduces orientation drift by assuming a cyclical movement, and by defining a functional coordinate system with two functional axes. These axes are based on the mean acceleration and rotation axes over multiple complete gait cycles. Using this drift-free orientation estimate, the displacement of the sensor is computed by again assuming a cyclical movement. Drift in displacement is reduced by subtracting the mean value over five gait cycle from the free acceleration, velocity, and displacement. Estimated 3D sensor orientation and displacement for an IMU on the lower leg were validated with an optical motion capture system (OMCS) in four runners during constant velocity treadmill running. Root mean square errors for sensor orientation differences between DFOD and OMCS were 3.1 ± 0.4° (sagittal plane), 5.3 ± 1.1° (frontal plane), and 5.0 ± 2.1° (transversal plane). Sensor displacement differences had a root mean square error of 1.6 ± 0.2 cm (forward axis), 1.7 ± 0.6 cm (mediolateral axis), and 1.6 ± 0.2 cm (vertical axis). Hence, DFOD is a promising 3D drift-free orientation and displacement estimation method based on a single IMU in quasi-cyclical movements with many advantages over current methods.

This paper presents a novel mechanism concept of laparoscope holders used for minimally invasive surgery (MIS). The mechanism is made of a parallelogram linkage and a parallel mechanism, which, respectively, serve as a robotic positioning arm and an orientating wrist of the holder. Due to its special geometry, the mechanism possesses several interesting kinematic properties. First, the laparoscope, which is held by the end-effector, can illustrate a remote center-of-motion (RCM) kinematics at the surgical incision point. Second, the position of the RCM point is solely defined by the parallelogram, whereas the orientation and insertion length of the laparoscope are governed by the parallel mechanism. Such an arrangement suggests a decoupled positioning and orientating manipulation for the holder, which is clinically helpful in laparoscopic MIS. Third, the overall mechanism including the parallelogram linkage and the parallel mechanism can be statically balanced at any configuration within the workspaces by using common linear springs. In other words, no electrical actuation or mechanical locks are required for making the laparoscope rest at any position and orientation. The design procedure for static balancing is detailed in the paper, and the theoretical formulation of the statically balanced mechanism is verified by a numerical example and computer simulation. The computer-aided design (CAD) model of the holder is constructed for evaluating its workspace and a physical prototype using commercial springs is built up and tested. It shows that the prototype that uses nonideal (commercial) springs can be statically balanced within the overall workspace, since the shortage/overshoot of the potential energy in the positioning mechanism and orientating mechanism, which are theoretically 6.8% and 5.1% of their total potential energies in maximum, are fully compensated by the friction effect.

Objective To explore the value of minimally invasive surgery training for postgraduates' laparoscopic skill. Methods Totally 60 undergraduates or surgical students were divided into experimental and control group, with 30 cases in each group. The experimental group received minimally invasive surgery training including theory teaching and operation training. The control group did not receive special teaching but self-learning during internship stage. The effect of teaching was evaluated by examination and questionnaire. The data were analyzed through Chi-square and t-test test. Results Before the learning of minimally invasive surgery courses, the examination scores of the experimental group and the control group were quite similar. After the minimally invasive surgery learning, the examination scores of the experimental group were significantly higher than that before the training (P<0.001), and the results were significantly higher than that of the control group (P<0.05). Conclusions The implement of minimally invasive surgery training promotes the mastery of the theoretical knowledge of minimally invasive surgery and improves the operational skill of endoscopic surgery. Key words: Minimally invasive surgery; Endoscopy surgery; Graduates of clinical Medicine

Mobile robots can be easily equipped with numerous sensors which can aid in the tasks of localization and ego-motion estimation. Two such examples are Inertial Measurement Units (IMU), which provide a gravity vector via pitch and roll angular velocities, and wide-angle or panoramic imaging devices. As the number of powerful devices on a single robot increases, an important problem arises in how to fuse the information coming from multiple sources to obtain an accurate and efficient motion estimate. The IMU provides real-time readings which can be employed in orientation estimation, while in principle an Omnidirectional camera provides enough information to estimate the full rigid motion (up to translational scale). However, in addition to being computationally overwhelming, such an estimation is traditionally based on the sensitive search for feature correspondences between image frames. In this paper we present a novel algorithm that exploits information from an IMU to reduce the five parameter motion search to a three-parameter estimation. For this task we formulate a generalized Hough transform which processes image features directly to avoid searching for correspondences. The Hough space is computed rapidly by re-treating the transform as a convolution of spherical images.

Objective To study the combined used of endoscopic retrograde cholangiopancreatography (ERCP) and laparoscopic surgery in the treatment of Mirizzi syndrome and in the prevention of bile duct injury in minimally invasive surgery. Methods A retrospective analysis was conducted on patients who suffered from Mirizzi syndrome treated with ERCP and laparoscopic surgery from March 2011 to February 2016 at the Center Hospital of Xianyang City, Southern Medical University. Results Of 1762 patients who underwent ERCP, 56 patients were diagnosed to suffer from Mirizzi syndrome (3.2%). Thirty-six patients with type Ⅰ disease successfully completed LC. The adjacent tissues were used to repair the defects in the first stage for type Ⅱ disease in 12 patients and for type Ⅲ disease in 4 patients. T tube was not used. The bile was drained with a ENBD drainage tube. After LC, a bile duct to jejunum Roux-en-Y anastomosis was carried out for the type Ⅱ disease in 2 patients and for the type Ⅲ disease in 2 patients. There was no perioperative death for the whole group of patients. Two patients developed symptoms of cholangitis, and the disease was stable after non-operative treatment. For the other patients, follow-up for more than 2 years showed good results. Conclusions ERCP was useful in the diagnosis of Mirizzi syndrome and in the Csendes typing before operation. ENBD could be used as a guide to find the hepatic duct, thus avoiding bile duct injury during laparoscopic surgery and for the placement of T tube drainage. ERCP combined with laparoscopic surgery in the treatment of Mirizzi syndrome was safe and effective. It is an operation which has the advantage of minimal trauma, less pain and rapid recovery. Key words: Mirizzi syndrome (MS); Endoscopic retrograde cholangio pancreatography (ERCP); Endoscopic nasal biliary drainage (ENBD); Laparoscope surgery; Cholecystectomy; Bile duct injury