This paper proposes a novel 4-DoF Remote Center of Motion (RCM) mechanism based on a serial-parallel hybrid architecture, denoted as (2-RRRRR-RR)+C. Featuring an overconstrained configuration, the design is specifically engineered to enhance structural stiffness and improve metrological accuracy. The parallel module consists of two orthogonally arranged planar branch chains integrated with a circular-arc branch that effectively suppresses parasitic motion, while the serial end-effector incorporates a specialized decoupled cylindrical gear assembly. This architecture achieves fully decoupled 4-DoF motion, significantly bolstering the safety and reliability of the surgical robot system. A physical prototype was developed and subjected to comprehensive kinematic modeling, Jacobian analysis, and singularity assessments. Furthermore, dimensional optimization based on the Local Transmission Index (LTI) was implemented to maximize motion/force transmission efficiency and workspace volume. Experimental investigations validate an expansive orientational workspace, supporting full 360° axial rotation within a 100° conical envelope, alongside a 100 mm translational range. Metrological evaluations yielded average absolute and repeatable positioning errors of 58.52 μm and 25.77 μm, respectively. The average Remote Center of Motion (RCM) deviation and tilt errors were quantified at 33.34 μm and 0.085°, confirming high-fidelity precision. Finally, simulated nasal cavity-probing tasks demonstrated an average target-point transition time of 71 seconds. These outcomes underscore the potential of the proposed mechanism for robotic endonasal skull base surgery, offering compatibility with relevant surgical instruments and enabling precise manipulation in confined surgical environments.

This review highlights the advantages of transanal quasi-single-port surgery (taQSPS) and offers a comprehensive analysis of the development, current applications, and future trends of robotic systems utilized in taQSPS. Timely surgical intervention is crucial for optimal outcomes in rectal cancer treatment, with techniques evolving from open surgery to endoscopic surgery and, more recently, to taQSPS. This innovative technique accesses lesions via a transanal route while utilizing instruments and methods similar to those in single-port surgery (SPS). Building on this foundation, SPS robotic surgical systems have emerged as a promising advancement for taQSPS, offering enhanced precision and maneuverability. However, despite their progress, general-purpose SPS robotic systems are often limited by their bulky design and lack of adaptability to the rectal cavity. In contrast, specialized taQSPS robotic systems are tailored to transanal procedures’ unique anatomical and operational demands, making them highly suitable for such surgeries. This review highlights the potential of specialized taQSPS robotic systems, serving as a valuable reference for researchers and clinicians, and aims to promote further development and adoption of these systems in clinical practice.

This paper presents a serially configured 3-DOF master manipulator designed for laparoscopic exploration, intended to control a slave manipulator within a surgical robotic system. The master manipulator integrates servo motors as force feedback units, resulting in a compact and easily assembled structure. The serial configuration enhances operational intuitiveness and shortens the learning curve for operators. Kinematic and Jacobian analyses of the proposed master manipulator are presented in this paper. The workspace experiments revealed a Y-axis rotational range of 161.44° and a Z-axis rotational range of 144.33°, along with a translational range of 108.31mm. Furthermore, an experiment for the laparoscopic simulated exploration was conducted, demonstrating that the proposed master manipulator successfully met the operational requirements for controlling the slave manipulator during laparoscopic exploration.

Robot-assisted transoral surgical procedures have emerged as minimally invasive solutions for addressing pathologies in the head and neck regions and airway structures. This review provides a comprehensive evaluation of current robotic systems utilized in robot-assisted transoral surgical procedures and categorizes them according to the depth of transoral access, ranging from robot-assisted transoral laser microsurgery to transoral robotic surgery, and extending to robot-assisted tracheal intubation. The detailed analysis highlights the evolution of their design principles, evaluates their clinical applicability, and discusses the associated inherent limitations. Key technological advancements identified include the increasing specialization of commercial robotic systems, the integration of force and shape sensing capabilities, and significant progress toward higher levels of surgical autonomy. This review systematically outlines current advancements and emerging trends in robot-assisted transoral surgical systems, aiming to inform and guide future research in this field.

This article introduces a DNA-inspired continuum joint (DICJ) for enhancing the performance of flexible endoscopic instruments. The proposed joint mimics the structural properties of DNA molecules, including an outer helical structure and four coaxially nested inner helical backbones, improving compressive and torsional stiffness. This biomimetic design leverages a stable multihelix configuration to enhance mechanical properties, such as minimal stress concentration, improved flexibility for large bending angles, constant curvature, and high payload capacity. FEA-based simulations and kinematic analysis were conducted to optimize the structure, demonstrating superior stiffness and reduced parasitic motion. Experimental investigations on the structural performance revealed excellent constant curvature characteristics, with a maximum bending angle of 242.7 degrees, and significantly improved torsional and axial stiffness (1.324 mNm/degrees and 2.948 N/mm, respectively). The DICJ joint exhibited a maximum payload capacity of 10 N. Experiments on visual coverage and obstacle avoidance showed enhanced dexterity and expanded the surgical field of view, validating the potential of the DICJ joint for minimally invasive surgery, with notable improvements in workspace and loading capabilities.

This paper proposes a novel 7-DoF operator interface based on a redundantly actuated parallel architecture of 2(RRRS)-RRRSP. This design effectively avoids the workspace-internal singularities, thereby addressing the limitations associated with the orientational workspace of traditional parallel operator interfaces. Furthermore, the redundantly actuated mechanism enables 3-DoF full actuation of each branch chain, and the motors are specially positioned near the base, significantly reducing the operating inertia without the need for gravity compensation. This arrangement contributes to a reduction in operator fatigue during prolonged operation. A hybrid tendon-linkage transmission is utilized in the operator interface to enhance its positioning accuracy. A prototype of the operator interface has been developed, and its kinematics along with the Jacobian have been derived. Optimization of structural parameters has been executed to enhance operational dexterity and relative workspace. Static force analysis has been conducted, and a strategy for static force output has been implemented to effectively decouple the interference between the clamping feedback force and the six-dimensional spatial feedback force. Experimental investigations on the translational and orientational workspace are carried out. The results demonstrate an expansive translational workspace measuring 315 mm (X), 248.5 mm, and 133.8 mm (Z), along with a wide range of orientation angles [-108 degrees, 98 degrees] alpha, [-134 degrees, 134 degrees] beta and [-115 degrees, 115 degrees] gamma. Trajectory tracking experiments have been performed and yielded an average error value of 1.021mm. The accuracy of the feedback force output has been studied, with average errors in output force recorded as 0.084 N (X), 0.124 N (Y), and 0.237 N (Z). Investigations into decoupling capability have been carried out, with average output errors of the clamping force at 5 N and 7 N operating forces in X and Y directions recorded as 0.095 N and 0.081 N, respectively. The experimental results demonstrate its potential for integration into RAMIS systems to align with diverse configurations of slave manipulators.

The paper introduces a novel robotic system for transanal endoscopic microsurgery (TEM) with a master-slave operated configuration. This slave manipulator features a modular distal continuum section, comprising two 7-DoF surgical instruments and a 5-DoF endoscopic arm designed to enhance hand-eye coordination and instrument triangulation in narrow and shallow rectal spaces. Key innovations include the hybrid coaxial continuum unit (HCCU) for improved bending characteristics and structural stiffness, and a design optimization for dexterity under anatomical constraints. Experimental validations demonstrate the system's precision and capability in simulated surgical tasks, highlighting its potential for advanced TEM applications with improved operational dexterity and reduced view obstruction.

This work proposes a novel flexible manipulator consisting of a series of 2-DOF vertebrae based on a ball-and-socket joint that is connected by a ball-shaped surface and a cup-shaped socket and constrained by pins for circumferential rotation. This manipulator can demonstrate outstanding torsional stiffness since the circumferential rotation between the vertebrae is constrained by four ball pins. The point contact between ball pins and guideways effectively reduces the friction between the vertebrae, thus allowing the designed manipulator to yield a smooth bending shape with constant curvature. This manipulator features high axial and torsional stiffness, excellent bending performance, sufficient loading capacity, and convenient integration with surgical instruments. Moreover, the excellent torsional stiffness enables this manipulator to efficiently transfer torque and be applied in in-situ torsional motion, effectively addressing the typical issue of limited dexterity for torsional motion. The kinematic modeling of the proposed manipulator under in-situ torsional motion has been derived, and its workspace has been analyzed. A robotic system has been assembled, and experiments have verified the proposed design and modeling validity. The results show that the maximum position errors in bending motion are 2.39% (horizontal direction) and 1.98% (vertical direction), and its torsional stiffness is 21.13N $\cdot $ mm/deg, which is 46 times higher than that of a typical spherical flexible manipulator (SFM). Such merits support this manipulator excellently performing the in-situ torsional motion with a maximum average position error of 3.58%. Furthermore, a phantom test of the larynx has been performed to verify the potential of clinical feasibility.

The flexible ureteroscope suffers from complex inherent motion hysteresis behaviors due to the lengthy and slender configuration with a typical diameter of less than 3mm, the manual cable-driven approach via tendon-sheath mechanism for force and motion transmission and the associated nonlinear dead zone caused by tendon slackening at around the zero position. The highly constrained intraluminal environment and the lack of sensor integration have further limited the feedback acquisition for closed-loop control. Therefore, the hysteresis compensation for the ureteroscopes has become more essential but remains challenging. To address the associated hand-eye incoordination, limited control accuracy, and increased surgical risks, this work presents an analytical modeling and feedforward compensation method for the ureteroscope based on a modified generalized Prandtl-Ishlinskii (MGPI) model. The designed model cascades a piecewise-linear-envelope-function-based symmetric generalized PI model (SGPI) and a two-sided dead zone model (DZ) to characterize the backlash, asymmetric hysteresis, and nonlinear dead zones. The feedforward compensator has been analytically derived and integrated into a motorized ureteroscope platform. Experimental results indicated that the proposed model has successfully captured the complex hysteresis with a modeling error of only 1.44% within a wide motion range of 440°. The tracking experiments of periodic and non-periodic signals have been performed. The results indicated that the proposed compensator has significantly suppressed the hysteresis by 60%~70% under different circumstances. Comparison simulations and experiments with other compensators have also demonstrated its advantages.