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.

Dimensional optimisation and an inverse kinematic solution method of a safety-enhanced remote centre of motion manipulator

BACKGROUND

With the expansion of minimally invasive surgery (MIS) applications in surgery, the remote centre of motion (RCM) manipulator requires a more flexible workspace to meet different operation requirements. Thus, the mechanical structure and motion control of the RCM manipulator play important roles.

METHODS

A multi-objective genetic algorithm was exploited to maximise the kinematic performance and obtain a compact structure of the RCM manipulator. An inverse kinematic solution method is proposed to meet task accuracy and kinematic singularity avoidance constraints for safety motion control.

RESULTS

Simulation results demonstrate that there are significant improvements in the reachable workspace inside the abdominal cavity, the flexibility of the workspace, kinematic performance, and compactness of the RCM manipulator. Experiments verify the feasibility of the prototype and the validity of the proposed inverse kinematic solution method.

CONCLUSIONS

This enhances the adaptability and safety of the RCM manipulator and provides potential prospects for MIS application.

Design and Performance Verification of a Novel RCM Mechanism for a Minimally Invasive Surgical Robot

Minimally invasive surgical robots have the advantages of high positioning accuracy, good stability, and flexible operation, which can effectively improve the quality of surgery and reduce the difficulty for doctors to operate. However, in order to realize the translation of the existing RCM mechanism, it is often necessary to add a mobile unit, which is often bulky and occupies most space above the patient's body, thus causing interference to the operation. In this paper, a new type of planar RCM mechanism is proposed. Based on this mechanism, a 3-DOF robotic arm is designed, which can complete the required motion for surgery without adding a mobile unit. In this paper, the geometric model of the mechanism is first introduced, and the RCM point of the mechanism is proven during the motion process. Then, based on the establishment of the geometric model of the mechanism, a kinematics analysis of the mechanism is carried out. The singularity, the Jacobian matrix, and the kinematic performance of the mechanism are analyzed, and the working space of the mechanism is verified according to the kinematic equations. Finally, a prototype of the RCM mechanism was built, and its functionality was tested using a master-slave control strategy.

Comparison of the short-term efficacy of two types of robotic total mesorectal excision for rectal cancer

BACKGROUND

The advantages and disadvantages of robotic technology compared with conventional surgery for low rectal cancer have been discussed extensively. However, a few studies on the efficacy of total mesorectal excision (TME) with different robotic technologies have been reported. The aim of this study was to evaluate the efficacy of two types of robot-assisted TME (R-TME) compared with laparoscopic TME (L-TME).

METHODS

A prospective comparative study was conducted comparing da Vinci R-TME, Micro Hand S R-TME, and L-TME for rectal cancer. This study was registered with "Clinicaltrials.gov" (ID: NCT02752698) and approved by the Association for the Accreditation of Human Research Protection Program (AAHRPP) (Project number: T16007). Between January 2017 and May 2019, patients with rectal cancer (cT1-3NxM0) were prospectively registered in the Third Xiangya Hospital. The integrity of the TME sample served as the primary outcome. Secondary outcomes included the involvement of the circumferential and distal resection margins (CRM and DRM), number of lymph nodes retrieved, blood loss, operative time, conversion rate, comprehensive complication index score, the International Prostate Symptom score, the International Index of Erectile Function, and the Female Sexual Function Index.

RESULTS

Of 134 patients with rectal cancer (74 males, mean age [SD] 59.1 ± 8.27 years), 46 patients underwent laparoscopic TME, 45 patients underwent da Vinci R-TME, and 43 patients underwent Micro Hand S R-TME. There were no differences in results between the two types of R-TME. Compared with laparoscopic TME, significant reductions in blood loss (median 65.50 ml da Vinci; median 66.54 ml Micro Hand S vs median 95.04 ml L-TME p = 0.037 and p = 0.041, respectively) and conversion rate (2.2% da Vinci; 2.3% Micro Hand S vs 6.8% L-TME p = 0,040 for the comparison daVinci L-TME and p = 0.038 for the comparison Micro Hand S vs. L-TME) with da Vinci Si and Micro Hand S R-TME were noted, and significant increases in operation time (230.05 min da Vinci; 235.03 min Micro Hand S vs. 205.53 min L-TME p = 0.045 and p = 0.043, respectively) was observed. Additionally, more patients underwent TME with sphincter-preserving methods in the two R-TME groups based on the type of operation (da Vinci 97.7%; Micro Hand S 97.9% vs. L-TME 82% resulting in  p = 0.033 for the comparison daVinci L-TME and p = 0.035 for the comparison Micro Hand S vs. L-TME). In comparison with L-TME, there was a larger number of lymph nodes retrieved (da Vinci mean 17.54; Micro Hand S mean 17.32 vs. L-TME mean 14.96 p = 0.031 for the comparison daVinci L-TME and p = 0.033 for the comparison Micro Hand S vs L-TME) and less blood loss (da Vinci mean 65.50 ml; Micro Hand S mean 66.54 ml vs. L-TME mean 95.04 ml, p = 0.037 for the comparison daVinci L-TME and p = 0.041 for the comparison Micro Hand S vs. L-TME), and incidence of severe postoperative complications was similar among three TME groups except for the earlier recovery of urogenital function (mean IPSS score da Vinci 7.73±1.35; Micro Hand S7.75±1.47 vs L-TME 14.26±1.41 p<0.001 for the comparison da Vinci L-TME and p<0.001 for the comparison Microhand S vs L-TME) in the two R-TME groups.

CONCLUSIONS

In our study, compared with laparoscopic surgery, da Vinci or Micro Hand R-TME exhibited similar superiority in the quality of oncologic resection, postoperative morbidity, and recovery of postoperative function.

Realization of Force Detection and Feedback Control for Slave Manipulator of Master/Slave Surgical Robot

Robot-assisted minimally invasive surgery (MIS) has received increasing attention, both in the academic field and clinical operation. Master/slave control is the most widely adopted manipulation mode for surgical robots. Thus, sensing the force of the surgical instruments located at the end of the slave manipulator through the main manipulator is critical to the operation. This study mainly addressed the force detection of the surgical instrument and force feedback control of the serial surgical robotic arm. A measurement device was developed to record the tool end force from the slave manipulator. An elastic element with an orthogonal beam structure was designed to sense the strain induced by force interactions. The relationship between the acting force and the output voltage was obtained through experiment, and the three-dimensional force output was decomposed using an extreme learning machine algorithm while considering the nonlinearity. The control of the force from the slave manipulator end was achieved. An impedance control strategy was adopted to restrict the force interaction amplitude. Modeling, simulation, and experimental verification were completed on the serial robotic manipulator platform along with virtual control in the MATLAB/Simulink software environment. The experimental results show that the measured force from the slave manipulator can provide feedback for impedance control with a delay of 0.15 s.

Comparison of the short-term operative, Oncological, and Functional Outcomes between two types of robot-assisted total mesorectal excision for rectal cancer: Da Vinci versus Micro Hand S surgical robot

OBJECTIVE

This study aimed to evaluate the difference of two various robotic technology applied in R- Total mesorectal excision (TME).

METHODS

From May 2017 to December 2018, consecutive patients with rectal cancer who underwent da Vinci R-TME or Micro Hand S R-TME were enrolled. The comparative study was conducted on Short-term Operative, Oncological, and Functional Outcomes between two type of R-TME.

RESULTS

47 patients underwent da Vinci R-TME, and 43 patients underwent Micro Hand S R-TME. No difference occured between two groups in TME completeness, CRM, DRM, CRM involvement and DRM involvement, operative time, blood loss, protective ileostomy, conversion rate, number of retrieved lymph nodes, Comprehensive Complication Index (CCI), International Prostate Symptom Score (IPSS) or Wexner scores. However, the setup time in the Micro Hand S group was longer.

CONCLUSIONS

In the present study, both da Vinci R-TME and Micro Hand S R-TME achieve excellent TME quality with acceptable morbidity and postoperative function.

Full-Dimensional Intuitive Motion Mapping Strategy for Minimally Invasive Surgical Robot With Redundant Passive Joints

Adding redundant passive joints to a robotic arm is an effective way to make the robot overcome the inherent incision constraint of minimally invasive surgery (MIS). However, due to the limited motion accuracy, it is difficult to realize full-dimensional intuitive motion based on traditional multi-axis coordinated control technology in this kind of MIS robots. To solve this problem, a separated position and orientation mapping strategy for MIS robot with redundant passive joints is proposed in the paper. The position and orientation mapping of the strategy are realized by coordinate motion control and joint direct control technique, respectively. To realize the intuitive motion under this condition, an inverse motion mapping method is further proposed. Compared with the existing mapping strategy, the proposed strategy is much more compact as the orientation mapping is greatly simplified. A large number of in vivo trials based on the newly developed prototype have been conducted and results fully verify the effectiveness of the proposed strategy.

Design and experimental study of a novel 7-DOF manipulator for transrectal ultrasound probe

Traditional hand-held ultrasound probe has some limitations in prostate biopsy. Improving the localization and accuracy of ultrasound probe will increase the detection rate of prostate cancer while biopsy techniques remain unchanged. This paper designs a manipulator for transrectal ultrasound probe, which assists doctors in performing prostate biopsy and improves the efficiency and accuracy of biopsy procedure. The ultrasound probe manipulator includes a position adjustment module that can lock four joints at the same time. It reduces operating time and improves the stability of the mechanism. We use the attitude adjustment module designed by double parallelogram RCM mechanism, the ultrasound probe can realize centering and prevent its radial motion. The self-weight balance design helps doctors operate ultrasound probe without weight. Using MATLAB to analyze the manipulator, the results show that the workspace of the mechanism can meet the biopsy requirements. And simulate the centering effect of the ultrasound probe when the attitude is adjusted at different feeding distances, the results show that the ultrasound probe is centering stability. Finally, the centering and joint interlocking tests of the physical prototype are completed. In this paper, a 7-DOF manipulator for transrectal ultrasound probe is designed. The mechanism is analyzed for kinematics, workspace analysis, simulation of centering effects, development of a physical prototype and related experimental research. The results show that the surgical demand workspace is located inside the reachable workspace of the mechanism and the joint locking of the manipulator is reliable.

Dimensional synthesis and concept design of a novel minimally invasive surgical robot

A new minimally invasive surgical (MIS) robot consisting of a spherical remote center motion (RCM) mechanism with modular design is proposed. A multi-objective dimensional synthesis model is presented to obtain the excellent performance indices. There are four objectives: a global kinematic index, a compactness index, a global comprehensive stiffness index, and a global dynamic index. Other indices characterizing the design requirement, such as workspace, mechanical parameter, and mass, are chosen as constraints. A new decoupled mechanism is raised to solve the coupled motion between the linear platform and the four degrees of freedom (DoF) of surgical instrument as a result of post-driving motors. Another new mechanical decoupled method is proposed to eliminate the coupled motion between the wrist and the forceps, enhance the dexterity of surgical instrument, and improve the independence of each motor. Then, a 7-DoF MIS robotic prototype based on optimization results has been built up. Experiment results validate the effectiveness of the two mechanical decoupled methods. The position change of the RCM point, accuracy, and repeatability of the MIS robot meet the requirements of MIS. Successful animal experiments validate the effectiveness of the novel MIS robot.