Abstract
Current laparoscopic techniques for achieving a safe hysterectomy rely heavily on manipulating and stabilizing the uterus using a transvaginal uterine elevator. Commercially available uterine manipulators are rigid in design and lack attributes like flexibility for pose control, force sensing or ease of adaptability. The current technique in using uterine elevator is to have an assistant manually reposition the uterus in response to the surgeon's command. Inefficient response to these commands, lack of experience, poor commands by the surgeon or fatigue are some of the issues arising from the use of the current manipulation technique. Furthermore, the manipulation of a rigid and stiff uterine elevator could potentially damage the uterine wall. A flexible uterine manipulator which can be controlled remotely whilst the surgeon is sitting at the operating console would be a big step forward in advancing robotic gynaecological surgery. These issues motivate this research on the development of an innovative flexible uterine elevator. This research was aimed at developing pneumatically controlled, octopus inspired robotic exible uterine manipulator, GENTLER (Gynaecological ENdoscopic uTerine eLEvatoR), based on soft continuum mechanism with integrated force and pose sensors. The use of soft robotics technology for practical applications requires modelling of the shape, movement and dynamics of the robot. Based on the literature, efforts in modelling the behaviour of this manipulator have focused mainly on kinematic modelling, while dynamics of the system is poorly studied which restricts the full potential of the technology. Another aspect that remains open is robust or stiffness control design of this pneumatically driven soft tube. Variable stiffness control is of prime importance to achieve the accuracy required to satisfy the desired position and force commands. Therefore, this research focused on the development of material-based dynamic modelling, a novel approach to embody the inherent nonlinearity exhibited by soft continuum manipulator as well as the design of real-time tunable stiffness control. Semi-empirical approach was used, which combined both theoretical modelling and experimental analysis of data obtained in laboratory to develop the model and the control architecture. Finally, the proposed modelling approach and control architecture were implemented into the prototype of GENTLER. The working prototype was validated in real-time using ex-vivo testing.