A single port surgical robot system with novel elbow joint mechanism for high force transmission

Development and experiments of a continuum robotic system for transoral laryngeal surgery

PURPOSE

Currently, self-retaining laryngoscopic surgery is not suitable for some patients, and there are dead zones relating to surgical field exposure and operation. The quality of the surgery can also be affected by the long periods of time required to complete it. Teleoperated continuum robots with flexible joints are expected to solve these issues. However, at the current stage of developing transoral robotic surgery systems, their large size affects the precision of surgical operative actions and there are high development and treatment costs.

METHODS

We fabricated a flexible joint based on selective laser melting technology and designed a shallow neural network-based kinematic modeling approach for a continuum surgical robot. Then, human model and animal experiments were completed by master-slave teleoperation to verify the force capability and dexterity of the robot, respectively.

RESULTS

As verified by human model and animal experiments, the designed continuum robot was demonstrated to achieve transoral laryngeal surgical field exposure without laryngoscope assistance, with sufficient load capability to finish the biopsy of vocal fold tissue in living animals.

CONCLUSION

The designed continuum robotic system allows the biopsy of vocal fold tissue without laryngoscope assistance. Its stiffness and dexterity indicate the system's potential for applications in the diagnosis and treatment of vocal fold nodules and polyps. The limitations of this robotic system as shown in the experiments were also analyzed.

Analysis of tendon tension and hysteresis by tendon twisting and development of anti-twist tendon mechanism of robotic surgical instruments

BACKGROUND

Control of the joints of robotic surgical instruments is difficult owing to hysteresis, and tendon twisting due to axial rotation of surgical tools also causes hysteresis. Therefore, a new mechanism is needed to prevent tendon twisting.

METHODS

Tendon tension and hysteresis change were analyzed by observing the movement of the joint depending on whether the tendons twisted for the same input signal. An anti-twist tendon mechanism to prevent twisting was developed. A 3-mm needle driver applied with the proposed mechanism was manufactured.

RESULTS

The anti-twist mechanism makes no tension change because of twisting or friction between the tendon and the system, i.e., the operating performance was the same regardless of rotation.

CONCLUSION

The proposed mechanism has been verified and can be applied to small surgical instruments 3 mm in size. These findings can be applied in the development of instruments for precise surgeries such as microsurgery. This article is protected by copyright. All rights reserved.

Kinematic Decoupling Analysis and Design of a Biomimetic Robotic Elbow Joint

The research of a biomimetic robotic manipulator is based on the flexible characteristics of the human upper limb joint, and a biomimetic robotic elbow joint plays a very significant role in the kinematic control of the biomimetic robotic manipulator. Most robotic elbow joints encountered today have a common disadvantage of bad neutrality, low rotational capability, and poor biomimetics. To overcome some difficulties, this paper presents a novel biomimetic robotic elbow joint. The structural model of the elbow joint is described, and the position equation is solved. Secondly, the kinematic equation of the elbow joint is established, the kinematic decoupling performance evaluation index of the elbow joint is defined, the kinematic decoupling characteristics of the elbow joint are analyzed, and the kinematic decoupling performance map in the workspace is drawn. Thirdly, using the spatial model theory, the structural parameters of the elbow joint are optimized, the structural parameters are selected by the Monte Carlo method, and the novel biomimetic robotic elbow joint is designed. The analysis results showing the kinematic decoupling performance of the elbow joint are symmetrical and the kinematic decoupling performance decreases with the increase of the angle, and there is a good kinematic decoupling in the workspace of about 35% in the vicinity of the initial position. When the structural parameters of the elbow joint are R_e1 = 90 mm, R_e2 = 70 mm, and R_e3 = 30 mm, the elbow joint has a very good kinematic decoupling. This paper can lay a foundation for further analysis and research of the biomimetic robotic elbow joint.