Prostate cancer is the second most common cancer in men, and transrectal ultrasound (TRUS) guided biopsy is the standard method to diagnose prostate cancer. Accurate prostate segmentation in TRUS images is crucial for precise biopsy. Manual segmentation is laborious, while automated segmentation faces significant challenges due to the low signal-to-noise ratio, blurred boundaries, and presence of noise and artifacts. To address these issues, this paper proposes a 3D edge-attention denoising diffusion network, aiming to achieve high accuracy and generalizability for prostate segmentation in TRUS-guided biopsy. The proposed network incorporates an edge attention denoising U-Net (EAD U-Net) to extract and utilize desired edge information in TRUS images, improving the segmentation accuracy in challenging regions of the prostate. To reduce uncertainty and enhance network accuracy, we incorporate a Kalman fusion module, which utilizes the Kalman filter and all estimations from the EAD U-Net in reverse process to obtain the optimal segmentation estimation. The proposed network was evaluated using 1834 3D ultrasound images from two open-source datasets. Comparative experiments with existing methods demonstrate that our method surpasses state-of-the-art techniques, proving its effectiveness in prostate segmentation from TRUS images. The proposed method achieved an average Dice similarity coefficient of 92.92% and 94.0%, and the 95th percentile of Hausdorff distance of 1.07 mm and 0.77 mm on two datasets, demonstrating the potential to facilitate accurate MRI-TRUS fusion guided prostate biopsy.

To achieve en bloc resection of bladder tumor and the anterior tumor resection in transurethral resection of bladder tumor (TURBT), a cystoscope transurethral continuum robotic system has been proposed. A continuum cystoscope in the system needs to bend more than 180° and its base has translation, axial rotation, and tilt degrees of freedom to achieve full bladder accessibility. Under the constant-curvature assumption, the analytical solution of inverse kinematics already exists for multi-segment continuum robots with variable segment lengths and continuum robots with two inextensible segments. However, there is a lack of analytical inverse kinematics solution for continuum robots with features of the continuum cystoscope. Therefore, this paper proposes a novel and efficient inverse kinematics solving algorithm for the continuum cystoscope used in TURBT. The proposed method simplifies the inverse kinematics problem by constructing a robot plane coordinate and uses geometric relationships to derive a non-linear constraint equation containing only one intermediate variable. By solving this non-linear equation, the solution to the entire inverse kinematics problem is obtained. Additionally, based on this inverse kinematics algorithm, the length of the continuum segment is designed to ensure full bladder accessibility. In the comparative experiments with the Jacobian-based method, which involves 12500 target poses, the proposed method solves 100% of the inverse kinematics problems with a much greater computational efficiency.

Needle-based procedures, such as biopsy and percutaneous tumor ablation, highly depend on the accuracy of needle placement. The accuracy is significantly affected by the needle-tissue interaction no matter what needles (straight or steerable) are used. Due to the unknown tissue mechanics, it is challenging to achieve high accuracy in practice. This paper hence proposes a needle design with an articulated tip for increased steerability and improved needle path consistency. Due to the passive needle tip articulation, tissue mechanics always plays a dominant role such that the needle creates similar paths with approximately piece-wise constant curvature in different tissues. Kinematics model for the proposed needle is presented. The algorithms of path planning and needle tip pose estimation under external imaging modality are developed. Experimental verifications were conducted to demonstrate the needle's steerability as well as the target-reaching capability with obstacles avoidance.

Continuum manipulators can accomplish various tasks in confined spaces, benefiting from their compliant structures and improved dexterity. Confined and unstructured spaces may require both enhanced stiffness of a continuum manipulator for precision and payload, as well as compliance for safe interaction. Thus, studies have been consistently dedicated to design continuum or articulated manipulators with tunable stiffness to adapt to different operating conditions. This paper presents a continuum manipulator with independently tunable stiffness where the stiffness variation does not affect the movement of the manipulator's end-effector. Moreover, the proposed continuum manipulator is found to have analytical inverse kinematics. The design concept, analytical kinematics, system construction and experimental characterizations are presented. The results showed that the manipulator's stiffness can be increased up to 3.61 times of the minimal value, demonstrating the effectiveness of the proposed idea.

Fruitful developments on continuum robots have been witnessed in recent years due to their movements and manipulation capabilities in confined spaces. Due to the nature that a continuum robot has an infinite number of DoFs (Degrees of Freedom), majority of the existing systems deployed abundant actuators such that the robot can be controlled in separately modeled and actuated segments with constant or variable curvature. As the shape of a continuum robot is always jointly determined by its actuation and the interactions from the environment, it is hence worth exploring the opposite approach that how a task can be accomplished with a minimal number of actuators. This paper presents the first step of such an investigation where a slim 3-actuator continuum robot is actuated to reach different spatial locations under gravity. As the gravity greatly affects the robot's shape, a monocular camera, together with two UKFs (Unscented Kalman Filters), was used to concurrently estimate the robot's shape and the feature depth. Then the estimated shape can be used in updating the kinematics model of the robot to achieve motion control. Experiments were conducted to validate the effectiveness of the proposed shape estimation, which promises the motion control implementation in the near future work.

Snake-like manipulators can navigate and perform manipulation in confined spaces. Their recent implementations in surgical robots attracted a lot of attentions. These slender manipulators usually possess either a hyper-redundant articulated vertebrate structure or a continuum one. Primary design considerations usually converge to a balance between proper workspace and acceptable stiffness. Efforts have hence been constantly made to achieve higher or adjustable stiffness for a manipulator to widen its applications. This paper presents a simple continuum manipulator design with variable stiffness based on redundantly arranged elastic backbones and continuously constrained bending curvature. The design concepts, kinematics, a preliminary formulation for stiffness adjustment, system construction and experimental characterizations are elaborated. The results showed that the manipulator's stiffness can be increased up to 4.71 times of the value without the curvature constraining rod, indicating the efficacy of the proposed idea.

Differential mechanisms possess various forms and are applied in a wide spectrum of mechanical systems. This paper proposes to categorize differential mechanisms into kinematic differential mechanisms (KDMs) and continuum differential mechanisms (CDMs), and also introduces two CDMs. The working principle, structures, constructions, and kinetostatic analyses of the proposed planar and the spatial CDMs are elaborated upon. The planar CDM is compared with two widely used differential mechanisms made from pulleys and linkages to show its effectiveness using a simple construction. The spatial CDM could resolve one input into three outputs in a way different from two serially connected planar differential mechanisms. As demonstrated in experimentation, the spatial CDM could allow more isotropic distribution of the three outputs. The categorization, analyses, and applications of the CDMs might not only extend the IFToMM terminology on differential mechanisms, but also inspire more CDM designs with distinct responses and properties for adaptive mechanical systems.

Substantial progresses have been made in building versatile anthropomorphic prosthetic hands in the past two decades using emerging technologies. However the trade-offs between functionality, reliability, affordability, appearance, etc. have not been fully settled. Many existing designs, particularly the commercial prosthetic hands, are underactuated and they can realize various grasps through compliant structures or differential mechanisms. This paper presents the design of an underactuated prosthetic hand with one actuator using a continuum differential mechanism. Structure of the continuum differential mechanism is simple enough to allow all the components, including a battery pack, to be packed into the palm. The design concept, component descriptions, and hand constructions are elaborated. Experimental verifications are presented to demonstrate the efficacy of the proposed design.

Continuum manipulators attract a lot of interests due to their advantageous properties, such as distal dexterity, design compactness, intrinsic compliance for safe interaction with unstructured environments. However, these manipulators sometimes suffer from the lack of enough stiffness while applied in surgical robotic systems. This paper presents an experimental kinestatic comparison between three continuum manipulators, aiming at revealing how structural variations could alter the manipulators' stiffness properties. These variations not only include modifying the arrangements of elastic components, but also include integrating a passive rigid kinematic chain to form a hybrid continuum-rigid manipulator. Results of this paper could contribute to the development of design guidelines for realizing desired stiffness properties of a continuum or hybrid manipulator.

It is known that human controls muscles for hand poses in a coordinated manner and the coordination is referred to as a postural synergy. Using postural synergies, dexterous grasping tasks could be accomplished on a prosthetic hand via only a few (usually two) control inputs. Instead of implementing postural synergies digitally, this paper presents the design of a simple continuum mechanism for implementing the postural synergies mechanically. The design, fabrication and assembly of a prosthetic hand are firstly presented, followed by the synthesis of postural synergies from various grasping poses. Referring to the extracted postural synergies, structural parameters of the continuum mechanism are calculated based on a kinematics model. Experimental verifications are also presented to demonstrate the efficacy of the proposed idea.

SPAL (Single Port Access Laparoscopy) could lead to improved surgical outcomes but demands functional and effective next-generation surgical tools. Various manual tools and robotic assistant systems have been developed in response to the unmet needs of SPAL. This paper presents the concept, design considerations and experimental characterizations of a foldable stereo vision unit with integrated illumination. The vision unit can be inserted into the abdomen through a Ø12mm trocar in a cylindrical laparoscope form. It can then unfold itself into a working configuration, providing 3D visualization of the surgical site as well as a remaining access port for manipulation arms or surgical tools. Given its standalone features, the vision unit could either be used for SPAL in a robotic assistant system or be applied in a surgical setting with standard manual tools.

This paper proposed a design of an endoscopic stitching device for surgical obesity treatment using a N.O.T.E.S (Natural Orifice Translumenal Endoscopic Surgery) approach. This proposed N.O.T.E.S gastroplasty approach performs stitching and resizing of a stomach from inside, aiming at further reducing postoperative complications by avoiding the use of skin incisions. The presented design can be inserted into the stomach in a folded configuration and be unfolded into a working configuration to perform stitching. It uses pre-curved super-elastic NiTi (Nickel-Titanium) alloy needle to facilitate the stitching motion. Role of the NiTi needle is demonstrated in in-vitro tissue penetrating experiments, while deployment and stitching motions of this device are verified using simulations.