Omar W. Maaroof

A Comparative Study on Application of Decomposition Method in Function Generation Synthesis of Over-Constrained Mechanisms

Double-spherical six-bar linkage is one of the Bennett over-constrained 6R linkages. Kinematic synthesis of such linkages can be tedious and impossible to solve for analytically. In order to cope with higher number of unknowns in these types of linkages, decomposition method is a valuable tool. This paper focuses on the function generation synthesis of double-spherical six-bar linkage. Two procedures for applying decomposition method are explained. Two numerical studies are conducted for both procedures to evaluate the performance of each procedure.

Alternating error effects on decomposition method in function generation synthesis

In approximate function generation synthesis methods, error between the desired function’s output and designed mechanism’s output oscillate about zero error while crossing the zero error margin at precision points. The common goal of these methods is to minimize the error within the selected working region of the mechanism. For mechanisms like Bennett overconstrained six-revolute jointed linkages that have relatively large number of construction parameters, it is a difficult task to solve for them at once. Decomposition method enables to divide such linkages into two loops and independently solve for each loop with less construction parameters. Although some approximation methods are proven to produce smaller errors than others for a single-loop synthesis, in this work, it is shown that smaller errors are not guaranteed for a certain method when used along with decomposition method. Numerical examples indicate that in decomposition method, more attention should be given to the alternation of the error of each decomposed mechanism, rather than the approximation method used.

Physical Human-Robot Interaction: Increasing Safety by Robot Arm’s Posture Optimization

To have robot manipulators working alongside with humans is a necessity in service robots. Obviously, in these robotics applications, human safety has precedence over precision and repeatability, which are the most important qualification of the conventional industrial manipulators. The safety measures can be taken either in the hardware or in the software or in both. This work by using a redundant manipulator aims at providing a safety measure through controlling the self-motion of the manipulator. The self-motion of the manipulator is controlled to change the posture of the manipulator to minimize or maximize the forces it can exert along a given direction. In this way, by knowing the location of the human or a delicate piece that it should not harm, manipulator’s posture is optimized to exert the minimum amount of forces during an unexpected collision. The control algorithm for this objective is described in this paper and it is evaluated through simulation tests on a redundant lightweight robot manipulator.

Unilateral Teleoperation Design for a Robotic Endoscopic Pituitary Surgery System

The aim of this study is to develop a teleoperation system which will be used to support the endoscopic pituitary surgery procedures. The proposed system aims to enable the surgeon to operate with three different operation tools (one of them is the endoscope) simultaneously. By this way, it is expected that the productivity of the surgical operation will be improved and the duration of the operation will be shortened. In the proposed system, a main control unit that can be attached to any of the surgical tools that are used in the operation (other than the endoscope) will be developed to capture the motion of the surgeon’s hand motion as demanded by the surgeon, to process the captured motion and to send it to the robot that handles the endoscope. In this way, the endoscope will be directed simultaneously by the surgeon throughout the operation while he/she is using the other surgical tools with his/her two hands. In this paper, the study to determine the type and processing of information that is sent from the surgeon’s side to the endoscope robot is presented.

A New Objective Function for Obstacle Avoidance by Redundant Service Robot Arms

The performance of task-space tracking control of kinematically redundant robots regulating self-motion to ensure obstacle avoidance is studied and discussed. As the sub-task objective, the links of the kinematically redundant assistive robot should avoid any collisions with the patient that is being assisted. The shortcomings of the obstacle avoidance algorithms are discussed and a new obstacle avoidance algorithm is proposed. The performance of the proposed algorithm is validated with tests that were carried out using the virtual model of a seven degrees-of-freedom robot arm. The test results indicate that the developed controller for the robot manipulator is successful in both accomplishing the main-task and the sub-task objectives.