A Parallel Robot With Remote Centre-of-Motion for Eye Surgery: Design, Kinematics, Prototype, and Experiments

BACKGROUND

Millions of patients suffering from eye disease cannot receive proper treatment due to the lack of qualified surgeons. Medical robots have the potential to solve this problem and have attracted significant attention in the research community.

METHOD

This paper proposes a novel parallel robot with a remote centre of motion for minimally invasive eye surgery. Kinematics models, singularity and workspace analyses, and dimension optimisation are conducted. A prototype was developed, and experiments were conducted to test its mobility, accuracy, precision and stiffness.

RESULTS

The prototype robot can successfully perform the required motions, and has a precision ranging from 7 ± 2 μm to 30 ± 8 μm, accuracy from 21 ± 10 μm to 568 ± 374 μm, and stiffness ranging from 1.22 ± 0.39 N/mm to 10.53 ± 5.18 N/mm.

CONCLUSION

The prototype robot has a great potential for performing the minimally invasive surgery. Its stiffness meets the design requirement, but its accuracy and precision need to be further improved.

Stereotactic technology for 3D bioprinting: from the perspective of robot mechanism

Three-dimensional (3D) bioprinting has been widely applied in the field of biomedical engineering because of its rapidly individualized fabrication and precisely geometric designability. The emerging demand for bioprinted tissues/organs with bio-inspired anisotropic property is stimulating new bioprinting strategies. Stereotactic bioprinting is regarded as a preferable strategy for this purpose, which can perform bioprinting at the target position from any desired orientation in 3D space. In this work, based on the motion characteristics analysis of the stacked bioprinting technologies, mechanism configurations and path planning methods for robotic stereotactic bioprinting were investigated and a prototype system based on the double parallelogram mechanism was introduced in detail. Moreover, the influence of the time dimension on stereotactic bioprinting was discussed. Finally, technical challenges and future trends of stereotactic bioprinting within the field of biomedical engineering were summarized.

Prevalence of haptic feedback in robot-mediated surgery: a systematic review of literature

With the successful uptake and inclusion of robotic systems in minimally invasive surgery and with the increasing application of robotic surgery (RS) in numerous surgical specialities worldwide, there is now a need to develop and enhance the technology further. One such improvement is the implementation and amalgamation of haptic feedback technology into RS which will permit the operating surgeon on the console to receive haptic information on the type of tissue being operated on. The main advantage of using this is to allow the operating surgeon to feel and control the amount of force applied to different tissues during surgery thus minimising the risk of tissue damage due to both the direct and indirect effects of excessive tissue force or tension being applied during RS. We performed a two-rater systematic review to identify the latest developments and potential avenues of improving technology in the application and implementation of haptic feedback technology to the operating surgeon on the console during RS. This review provides a summary of technological enhancements in RS, considering different stages of work, from proof of concept to cadaver tissue testing, surgery in animals, and finally real implementation in surgical practice. We identify that at the time of this review, while there is a unanimous agreement regarding need for haptic and tactile feedback, there are no solutions or products available that address this need. There is a scope and need for new developments in haptic augmentation for robot-mediated surgery with the aim of improving patient care and robotic surgical technology further.

On the Value of Estimating Human Arm Stiffness during Virtual Teleoperation with Robotic Manipulators

Teleoperated robotic systems are widely spreading in multiple different fields, from hazardous environments exploration to surgery. In teleoperation, users directly manipulate a master device to achieve task execution at the slave robot side; this interaction is fundamental to guarantee both system stability and task execution performance. In this work, we propose a non-disruptive method to study the arm endpoint stiffness. We evaluate how users exploit the kinetic redundancy of the arm to achieve stability and precision during the execution of different tasks with different master devices. Four users were asked to perform two planar trajectories following virtual tasks using both a serial and a parallel link master device. Users' arm kinematics and muscular activation were acquired and combined with a user-specific musculoskeletal model to estimate the joint stiffness. Using the arm kinematic Jacobian, the arm end-point stiffness was derived. The proposed non-disruptive method is capable of estimating the arm endpoint stiffness during the execution of virtual teleoperated tasks. The obtained results are in accordance with the existing literature in human motor control and show, throughout the tested trajectory, a modulation of the arm endpoint stiffness that is affected by task characteristics and hand speed and acceleration.

Kinematic Design of a Generalized Double Parallelogram Based Remote Center-of-Motion Mechanism for Minimally Invasive Surgical Robot

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.