Ali Faraz

A Robotic Case Study: Optimal Design for Laparoscopic Positioning Stands

A positioning stand can help a surgeon with positioning and locking endoscopic tools, thereby avoiding the need foran assistant surgeon. The kinematic configuration of the positioning stand is comprised of two main parts: the arm (forpositioning), and the wrist (for orienting the tool). The main requirement of the wrist is to perform spherical movements around the incision point. A concentric multilink spher ical joint design has been developed for the wrist mechanism. The size synthesis is performed to minimize the overall size of the wrist, and also to maximize its range of angular movements. The type synthesis of the positioning arm has led to the use of a SCARA con figuration as a balanced and easily moved arm configuration. The size synthesis of the arm is carried out with the goal of minimizing its overall dimensions, based on the arms reachable workspace and manipulability. The integration of the wrist and arm is performed by optimizing the orientation of the wrist in such a way that the in terference between the wrist and the workspace of the surgeon is minimized.

Issues and Design Concepts in Endoscopic Extenders

Abstract Endoscopic surgery as a less invasive method of surgery, is more difficult to perform. The associated problems are visual issues, hand/tool’s movement, and force/tactile sensing. To overcome some of these difficulties, in this paper new design concepts are reviewed and proposed such as tools with flexible stem, suturing device, positioning stand, and robotic endeflectors for master-slave systems.

Towards approximate models of Coulomb frictional moments in : (I) revolute pin joints and (II) spherical-socket ball joints

In general, the rigid-contact assumption has been used to estimate the frictional moment between two bodies in contact. In a multi-body connection, two types of passive interconnection are considered in this paper, namely pin joint and spherical-ball joint. The joints are assumed to be passive at the localized configuration space of the multi-body systems and are assumed to be actuated remotely. The traditional approach for modelling such frictional contact does not consider the elastic deformation of joints. Two approximate models are presented for both revolute pin joints and spherical-socket ball joints. The proposed models offer a more accurate estimation of the Coulomb frictional moment. The new models offer a compact solution which can be easily extended to other geometrical multi-body contact configurations with various degrees of clearance. The proposed models can be used in the dynamic modelling and control of multi-body systems in frictional contact.

A robotic case study: optimal design for laparoscopic positioning stands

The positioning stand could help the surgeon to position and lock endoscopic tools without the need for an assistant surgeon. The kinematic configuration of the positioning stand comprises two main parts, the arm (for positioning) and the wrist (for orienting the tool). The main requirement of the wrist is to perform spherical movements around the incision point. A concentric multi-link spherical joint design has been developed for the wrist mechanism. The size synthesis is performed to minimize the overall size of wrist and also to maximize its range of angular movements. The type synthesis of the positioning arm has led to SCARA configuration, as a balanced and easy to move arm configuration. The size synthesis of the arm is carried out with the goal of minimizing its overall dimensions, based on reachable workspace and manipulability of the arm. The integration of the wrist and arm is performed by optimizing the orientation of wrist in such a way that the interference between the wrist and the workspace of surgeon is minimized.

Design of haptic interface through stiffness modulation for endosurgery: theory and experiments

In endosurgery, tissue manipulation is performed by long graspers which have poor force-reflection property, i.e. they do not reflect the grasping force to the hand of the surgeon. In the paper, a novel design of an electromechanical system is considered which can enhance the force-reflecting capability of endosurgical graspers. The type synthesis of such a haptic interface leads to the application of a tunable spring. The design of the tunable spring is optimized based on the haptic and surgical requirements. Moreover, by using suitable control laws, it is shown that the primary requirements of the design application can be met. Simulation and experimental results are presented using a prototype model of such a haptic interface to demonstrate the practicality of such a design concept.

On inverse kinematics and trajectory planning for tele-laparoscopic manipulation

Addresses the kinematic modelling, solutions and trajectory planning of a tele-laparoscopic manipulator. This type of manipulator can be used in remote positioning of laparoscopic tools through a tele-operating system. Specifically the paper models kinematics of a typical manipulating system which can be used in such tele-surgery. Inverse kinematics solutions are also obtained for two kinematically constrained motions which are part of a typical trajectory of the laparoscopic tools. These are fixed axis rotation of the tool and its straight line motion. Simulation results are presented to demonstrate the validity of such models and solutions.

Kinematic modelling and trajectory planning for a tele-laparoscopic manipulating system

This paper addresses the kinematic modelling, solutions and trajectory planning of a tele-laparoscopic manipulator. This type of manipulator can be used in remote positioning of laparoscopic tools through tele-operating system. Specifically the paper models kinematics of a typical manipulating system which can be used in such tele-surgery. Inverse kinematics solutions are also obtained for two kinematically constraint motions which are part of a typical trajectory of the laparoscopic tools. These are fixed axis rotation of the tool and its straight line motion. Simulation results are presented to demonstrate the validity of such models and solutions.

Design of a force control grasper through stiffness modulation for endosurgery: theory and experiments

Abstract In endosurgery, tissue manipulation is performed by long graspers which have a poor force-reflection property, i.e. they do not reflect the grasping force to the hand of the surgeon. In this paper, a novel design of an electro-mechanical system is considered which can enhance the force–reflecting capability of endosurgical graspers. The type of synthesis of such a haptic interface leads to the application of a tunable spring . The design of a tunable spring is optimized based on the haptic and surgical requirements. Moreover, by using suitable control laws, it is shown that the primary requirements of the design application can be met. Simulation and experimental results are presented using a prototype model of such a haptic interface to demonstrate the practicality of such a design concept.

Flexible Stem Graspers

Since the earliest times, humans have used tools to extend their ability to reach and move objects. One main application of tools has been to move objects for the purpose of a) positioning with three degrees of freedom (DOF), and b) orienting with an additional three DOF. The six DOF of the movement is defined as manipulation of the object [92].

Passive Robotics: Laparoscopic Stand

In laparoscopic surgery, the reverse hand movements and the limited force sensing of the remote surgical site, in conjunction with the indirect vision and the straining body posture of the surgeon, decrease his/her dexterity dramatically compared to open surgery. One possible method of enhancing dexterity is by external mechanisms which provides support for surgical tools outside the body.