## 4 Results and Discussion
### Soft-Tissue Cadaveric Cases  
Subsequently, five soft-tissue cadavers donated for educational research to Srinagarind Hospital, KKU, Thailand, were used in this study, with the Ethical approval #HE641206, waived by the Center for Ethics in Human Research, Khon Kaen University (KKU), on 13 May 2021. The first two cases were used for the requirement gathering process, then later, the proposed robot prototype was applied to a total laparoscopic hysterectomy in three soft-tissue cadavers. Figure 18 illustrates the layout of the operating theater, where the surgical assistant at the vaginal end was replaced by the uterine manipulator robot, which was controlled remotely via a joystick.  
Figure 19 shows the laparoscopic views of the experiments conducted on a cadaver with the help of extra light through a medium-size incision in the abdomen. Figure 19a-c,e depict when the **Roll** angle (\(\mathbf{\theta}\)) = 0\({}^{\circ}\) with varied **Pitch** angles (\(\mathbf{\varphi}\)) (0\({}^{\circ}\), 20\({}^{\circ}\), 40\({}^{\circ}\), and 60\({}^{\circ}\), respectively), while Figure 19d,f depicts when the motion **Pitch** angles (\(\mathbf{\varphi}\)) = 60\({}^{\circ}\) but the **Roll** angles (\(\mathbf{\theta}\)) are 20\({}^{\circ}\) and \(-20^{\circ}\).  
Figure 16: The motion composites of the uterus manikin model; (**a**) side view, and (**b**) front view.  
Figure 17: The uterus manikin model with varied **Pitch** and **Roll** angles.  
In addition to smoothly manipulating the uterus at the angular velocity of 4 degrees/second (0.67 RPM), the uterine manipulator robot also can steadily manipulate the uterus to various **Roll** and **Pitch** angles, exposing the root of the uterus along with other pelvic organs. According to the experimental surgeries in all five soft-tissue cadavers conducted in this work, the motions in the **Pitch** and **Roll** panels, which are required in a real operation, would involve only 30-80\({}^{\circ}\) and \(\pm\)15\({}^{\circ}\), respectively. Although these requirements are well within the capabilities of the proposed uterine manipulator robot involving (0-\(\sim\)90\({}^{\circ}\)) and \(\pm\)150\({}^{\circ}\) in the **Pitch** and **Roll** panels, respectively, if this robot is implemented as a fixed-tip uterine manipulator with RCM mechanism, as is the case for other previous related robots, those angles could cause discomfort around the vulva area where the instrument is inserted. As a result, the proposed robot incorporating the tiltable-tip uterine manipulator could be more beneficial in this respect.  
A design of a non-RCM 2-DoF robotic uterine manipulation system has been described for application in laparoscopic gynecologic surgery. The idea is to work with an existing, reusable and tiltable-tip uterine manipulator. A specific instrument has been chosen as a showcase here. However, the common design can be applied to any other tiltable-tip uterine manipulator, while a fixed-tip uterine manipulator would require an RCM mechanism.  
Figure 19: The results with extra external light during cadaver experiments; (**a–c,e**) showing when the **Roll** angle (\(\theta\)) = 0\({}^{\circ}\) with varied **Pitch** angles (\(\varphi\)) (0\({}^{\circ}\), 20\({}^{\circ}\), 40\({}^{\circ}\), and 60\({}^{\circ}\), respectively), while (**d,f**) showing when the motion **Pitch** angles (\(\varphi\)) = 60\({}^{\circ}\) but the **Roll** angles (\(\theta\)) are 20\({}^{\circ}\) and \(-\)20\({}^{\circ}\).  
Figure 18: Operating theater layout for soft-tissue cadaveric experiments.  
To date, this work has been designed and implemented carefully and tested extensively through simulations, models, and experiments on soft-tissue cadavers. Once ethical approval for research on human subjects is granted, this work could proceed to a clinical trial. The setup could remain the same as in experiments on soft-tissue cadavers, with the whole robotic system covered by a sterilized cover to avoid direct contact with the patient, and the uterine manipulator and the joystick will also be sterilized.