3 research outputs found
Fuzzy Logic Approach for Hybrid Position/Force Control On Underwater Manipulator.
A fuzzy logic control method for hybrid position/force control of underwater manipulator is proposed in this paper
Design, Modelling and Fabrication of a Robotic Retractor for Colorectal Surgery
PhDThis research presents the design, fabrication and controller development of a robotic
retractor which driven by a robotic manipulator for laparoscopic colorectal surgery. The
system consists of a dual-head fan retractor and a manipulator. The dual-head fan
retractor comprises two fan devices, retractor wrist, tubular element and handle. The fan
device is facilitated with a fan end-effector, an expansion mechanism and a clutchspring
mechanism. Two fan devices have been used in the system to provide an
anthropoid hand-holding shape which is specifically advanced for surgical purpose
because intestine tends to slip when subject to disturbance and the anthropoid handholding
shape can effectively halt that. One of the two fan devices is rotatable which
makes the anthropoid hand-holding shape achievable. The retractor wrist possesses a
triggering device, based on clutch-spring mechanism, for rotating the rotatable fan
device. The clutch-spring mechanism has an impact on rotating the palms of the fan
devices. In front of the handle, it is the so called front body which includes two fan
devices, retractor wrist and tubular element. The front body can be controlled and is
motorised using two motors fixed to the tubular element. The dual-head fan retractor is
modelled in SolidWorks, and stress analysis of the retractor has been carried out by
SolidWorks Simulation. Then, the mathematical model of the fan blades is developed.
A 3-joint manipulator is modelled and controlled by a computed torque PD control
approach as part of an investigative study to fit such a system to the retractor for robotic
manipulation. Based on this investigation, the retractor is attached to a 2-joint robotic
manipulator which has one rotational joint and a prismatic joint. This manipulator is mathematically modelled, and the dynamic equations are obtained. Control methods
from Azenha and Khatib are simulated and compared. Azenha & Machado’s method has
fewer input parameters and less oscillation when utilising the same control gains. Timeoptimal
control is then successfully developed for the above 2-joint manipulator. This
study clearly indicates that a retractor to be used for laparoscopic surgery can be
effectively controlled using a multi-joints and multi degrees of freedom robotic
manipulator