During vitreoretinal surgery, surgeons are required to precisely manipulate surgical tools within a confined workspace of an eye, which is roughly 2.5 cm spherical in shape. Because the surgical view can only be obtained by a microscope placed above the eyeball through the pupil, the eyeball needs to be moved or rotated during the operation to see a larger portion of the retina. At this point, general Remote Center of Motion (RCM) mechanisms require additional actuators or manual modification. On the other hand, a programmable RCM mechanism can reduce surgery time without a physical alignment procedure. This study introduces a novel six-degree-of-freedom (DoF) programmable RCM mechanism capable of generating the RCM at random positions in 3D space. Our approach combines two planar 5-bar linkage mechanisms placed in parallel, creating a double-layered configuration to establish the programmable RCM mechanism. We optimized the workspace of each planar mechanism to a customized workspace for a general eyeball model using genetic algorithms, focusing on maximizing the manipulability of the target workspace. The Phantom Omni device was utilized as a remote controller to remotely control the proposed mechanism in a transparent eyeball model with a diameter of 4 cm. Evaluation of the functionality of the programmable RCM mechanism at various RCM points showed that the overall error was less than 1 millimeter. The repeatability of the mechanism was tested and showed an accuracy of about 127 micrometers.

Magnetic resonance imaging (MRI) offers better visualization for diagnosis, interventional radiology, and surgery from other imaging modalities without X-ray exposure. Medical robots have provided solutions for many surgical and rehabilitation procedures. A symbiosis of MRI and robotics can allow manipulation in closed MR-gantry, decrease trauma, operation, and recovery time for patients and improve the dexterity, convenience, and surgical outcome for physicians. However, the inherent properties and limitations of MR scanners had hindered their development. Technological advancements in the field of computers, additive manufacturing, and sensing in the past decade have changed robotics and the focus shifted again toward MRI-compatible robots. This article provides a compendium of the state-of-the-art literature on robotic systems developed for the MRI environment presented between 2009 and 2021. The systematic review discusses surgical and fMRI study robots, the actuation, and sensing solutions developed to assist such robots, recent research emphasis, current limitations, and prospects.

Percutaneous intervention has attracted significant interest in recent years, but many of today's needles and catheters can only provide limited control of the trajectory between an entry site and soft tissue target. In order to address this fundamental shortcoming in minimally invasive surgery, we describe the first prototype of a bioinspired multipart probe that can steer along planar trajectories within a compliant medium by means of a novel “programmable bevel,” where the steering angle becomes a function of the offset between interlocked probe segments. A kinematic model of the flexible probe and programmable bevel arrangement is derived. Several parameters of the kinematic model are then calibrated experimentally with a fully functional scaled-up prototype, which is 12 mm in diameter. A closed-loop control strategy with feed-forward and feedback components is then derived and implemented in vitro using an approximate linearization strategy that was first developed for car-like robots. Experimental results demonstrate satisfactory 2-D trajectory following of the prototype (0.68 mm tracking error, with 1.45 mm standard deviation) using an electromagnetic position sensor that is embedded at the tip of the probe.

Percutaneous interventions have attracted significant interest in recent years, but most approaches still rely on straight line trajectories between an entry site and a soft tissue target. Thus, to this day, a flexible probe able to bend along predefined curvilinear trajectories within a highly compliant medium without buckling is still an open research challenge. In this paper, we describe the concept of a “programmable bevel” tip, which is inspired by the ovipositor of certain wasps: the offset between two parts of a probe determines the steering direction of the tip thanks to a set of bevels included at the tip of each segment. A kinematic model of the flexible probe and programmable bevel arrangement is derived. Several parameters of the kinematic model are calibrated experimentally using our first prototype of the flexible probe, codenamed STING. Open- (feed-forward) and closed-loop (feedback) control strategies are then derived and implemented in simulation using the chained form representation, originally developed to control car-like robots. Simulated results demonstrate accurate two-dimensional needle steering in the presence of velocity, position, and initial posture disturbances.

Shape is one of the useful information for object detection. The human visual system can often recognize objects based on the 2-D outline shape alone. In this paper, we address the challenging problem of shape matching in the presence of complex background clutter and occlusion. To this end, we propose a graph-based approach for shape matching. Unlike prior methods which measure the shape similarity without considering the relation among edge pixels, our approach uses the connectivity of edge pixels by generating a graph. A group of connected edge pixels, which is represented by an “edge” of the graph, is considered together and their similarity cost is defined for the “edge” weight by explicit comparison with the corresponding template part. This approach provides the key advantage of reducing ambiguity even in the presence of background clutter and occlusion. The optimization is performed by means of a graph-based dynamic algorithm. The robustness of our method is demonstrated for several examples including long video sequences. Finally, we applied our algorithm to our grasping robot system by providing the object information in the form of prompt hand-drawn templates.

This paper describes the development of a compact laparoscopic assistant robot system which functions as a camera assistant in laparoscopic surgery. The system allows 3-DOF motion and is mountable to a standard laparoscope holder. The 3-DOF motion includes 1-DOF translation and 2DOF bending motion for adjusting viewpoints. This compact system is designed so that viewing angles are adjusted within the abdomen using a bending section and thus, interference with the operating surgeon is reduced. Voice-controlled command input and visual-servoing are implemented for the control of the robot. Our preliminary experiments show a possible clinical use upon further improvement.

This paper describes a bone-mountable surgical robot system for hip surgery and its in vitro experiments with cadavers. The system eliminates the need for obtaining CT scan data by adopting gauge-based, bone-mounting registration method and is designed to replace only the broaching procedure, which is known to be the most error-prone procedure in the manual surgery. The performance of this system is evaluated with specimen of six human cadavers. X-ray images and photographed image of femurs are utilized for measuring the difference between the implant and the anatomical axes. As this deviation implies how the gait pattern of the operated patient may be influenced by the surgery, the amount of deviation is used as the indicative of system performance. The nominal differences of anteversion angle, valgus-varus angle, and flexion-extension angle are 0.02/spl plusmn/2.73/spl deg/, 0.98 /spl plusmn/0.39/spl deg/ and 0.51/spl plusmn/0.87/spl deg/, respectively. In case of the change in leg length after the surgery, the nominal error is -0.88/spl plusmn/1.26 mm. Experimental results show that the performance of the developed system is comparable to other surgical robots that use preoperative planning with CT scan data.

This paper presents a gauge-based registration method, a femur-mountable robot for hip arthroplasty named ARTHROBOT, and the surgery procedure using this system. In the gauge-based registration, a reamer-shaped gauge is inserted into the femoral medulla for relative positional information of the femur to the robot. A mounting frame and a minirobot are then mounted on the patient's femur for accurate machining. This gauge-based registration method drastically reduces the processes in preoperative planning by eliminating the need of computer tomography scanning or other image processing methods, compared to other robotic systems that are used for hip surgery. Also, this surgical system reduces damage to the femur because only the metaphyseal region of the femoral canal needs to be machined, while leaving the diaphyseal hard bone untouched. Experiments were performed on 18 composite bones and 12 pig bones. In the composite bone group, orientation (anterversion, varus/valgus and flexion/extension) errors were made at 0.13/spl deg//spl plusmn/0.77/spl deg/, 0.14/spl deg//spl plusmn/0.38/spl deg/, and -0.27/spl deg//spl plusmn/0.33/spl deg/, and the maximum position error was at 1.00 mm. In the pig bone group, orientation errors were made at -0.03/spl deg//spl plusmn/0.65/spl deg/, 0.31/spl plusmn/0.27/spl deg/, and -0.36/spl deg//spl plusmn/0.36/spl deg/, and the maximum position error was at 1.12 mm. Also, 93% of the gaps between the bone and the implant surface were under 0.25 mm. The developed system shows sufficient machining accuracy and precision for clinical application.

This paper presents the mechanism and surgical method for ARTHROBOT, a new surgical robot for hip arthroplasty. The robot is femur-mountable and capable of 4-DOF motion. It uses a new gauge-based registration method that utilizes measuring instrument consisting of a reamer-shaped block gauge and a distance-measuring device. This gauge-based registration method drastically reduces the processes in the preoperative planning by eliminating the need of inserting fiducial markers or CT scanning. From the preliminary performance evaluation, it is shown to have less than 0.3 mm machining error, which seems to be sufficiently accurate for clinical application. Since the system has low operating cost and is compatible to the conventional manual surgery, it is expected to be easily adaptable to surgical needs and practices in the operating room.

This paper presents mechanisms and control methods of a new surgery robot for total hip arthroplasty (THA). To minimize the disadvantages of the conventional registration method, a new gauge-based registration method has been proposed, and a 3-DOF robot has been developed that can be mounted on a femur The proposed surgical robot can operate along a pre-programmed path autonomously, in addition to allowing a surgeon to directly control the motion of the surgical robot with their experience and judgment during an operation. For this purpose, a master is attached to the surgical robot and admittance display is used in control. ARTHROBOT this new arthroplastic surgical robot system, is expected to be adaptable to surgical needs and practice in the operating room.