Dynamic simulation of task constrained of a rigid-flexible manipulator

A rigid-flexible manipulator may be assigned tasks in a moving environment where the winds or vibrations affect the position and/or orientation of surface of operation. Consequently, losses of the contact and perhaps degradation of the performance may occur as references are changed. When the environment is moving, knowledge of the angle α between the contact surface and the horizontal is required at every instant. In this paper, different profiles for the time varying angle α are proposed to investigate the effect of this change into the contact force and the joint torques of a rigid-flexible manipulator. The coefficients of the equation of the proposed rotating surface are changing with time to determine the new X and Y coordinates of the moving surface as the surface rotates

The Merits of Teaching Basic Courses in Engineering Curriculum

This paper tries to answer the question frequently asked by engineering students, why we are studying basic subjects such as Mathematics, Mechanics and Physics. Engineering students study these basic subjects in addition to some other courses such as computer programming, production, chemistry and some humanity courses during their first year of study as a preparatory year for all engineering disciplines. Students are expecting to study their major subjects in the first year of study when they enroll in faculty of engineering around the world. It is almost impossible to teach advanced subjects such as fluid mechanics, mechanical vibration, automatic control, modeling and simulation and robotics without prior knowledge of the basic courses. The students could not recognize in their first year of study that understanding basic mathematics and mechanics skills help them a lot in getting the knowledge of advanced courses easily and effectively. For example, all automatic control courses need some modelling techniques which the students can gain by studying engineering mechanics and calculus during their first level of study. Basic knowledge of Newton’s second law of motion and basic rules of calculus are very important in achieving satisfactory understanding of the advanced topics in all disciplines. Some of the advanced topics for example robot Jacobian is based on partial derivatives and the equations of motion of a multi-joints robot manipulator are based on Lagrange’s equation. The students cannot understand subjects such as heat transfer and thermal power stations and fluid mechanics without basic knowledge of physics

Optimal Point-to-Point Trajectory Tracking of Redundant Manipulators using Generalized Pattern Search

Optimal point-to-point trajectory planning for planar redundant manipulator is considered in this study. The main objective is to minimize the sum of the position error of the end-effector at each intermediate point along the trajectory so that the end-effector can track the prescribed trajectory accurately. An algorithm combining Genetic Algorithm and Pattern Search as a Generalized Pattern Search GPS is introduced to design the optimal trajectory. To verify the proposed algorithm, simulations for a 3-D-O-F planar manipulator with different end-effector trajectories have been carried out. A comparison between the Genetic Algorithm and the Generalized Pattern Search shows that The GPS gives excellent tracking performance.Comment: www.ars-journal.co

Optimum joint profile for constrained motion of a planar rigid-flexible manipulator

Dynamic system performance of a constrained rigid-flexible manipulator in contact with a circular surface is considered here. A dynamic model with zero tip deformation constraint is derived using extended Hamilton’s principle. An analytical approach for vibration of the flexible link using the assumed modes technique is presented. The effect the force exerted at the end-effector and the required joint torque is investigated through the solution of the inverse dynamics problem. Optimum system performance is suggested for the circular contact surfaces considered in this study using the minimum energy criteria for three joint motion profiles

Mortality of emergency abdominal surgery in high-, middle- and low-income countries

Background: Surgical mortality data are collected routinely in high-income countries, yet virtually no low- or middle-income countries have outcome surveillance in place. The aim was prospectively to collect worldwide mortality data following emergency abdominal surgery, comparing findings across countries with a low, middle or high Human Development Index (HDI). Methods: This was a prospective, multicentre, cohort study. Self-selected hospitals performing emergency surgery submitted prespecified data for consecutive patients from at least one 2-week interval during July to December 2014. Postoperative mortality was analysed by hierarchical multivariable logistic regression. Results: Data were obtained for 10 745 patients from 357 centres in 58 countries; 6538 were from high-, 2889 from middle- and 1318 from low-HDI settings. The overall mortality rate was 1⋅6 per cent at 24 h (high 1⋅1 per cent, middle 1⋅9 per cent, low 3⋅4 per cent; P < 0⋅001), increasing to 5⋅4 per cent by 30 days (high 4⋅5 per cent, middle 6⋅0 per cent, low 8⋅6 per cent; P < 0⋅001). Of the 578 patients who died, 404 (69⋅9 per cent) did so between 24 h and 30 days following surgery (high 74⋅2 per cent, middle 68⋅8 per cent, low 60⋅5 per cent). After adjustment, 30-day mortality remained higher in middle-income (odds ratio (OR) 2⋅78, 95 per cent c.i. 1⋅84 to 4⋅20) and low-income (OR 2⋅97, 1⋅84 to 4⋅81) countries. Surgical safety checklist use was less frequent in low- and middle-income countries, but when used was associated with reduced mortality at 30 days. Conclusion: Mortality is three times higher in low- compared with high-HDI countries even when adjusted for prognostic factors. Patient safety factors may have an important role. Registration number: NCT02179112 (http://www.clinicaltrials.gov)

OPTIMAL TRAJECTORY PLANNING OF MANIPULATORS: A REVIEW

Optimal motion planning is very important to the operation of robot manipulators. Its main target is the generation of a trajectory from start to goal that satisfies objectives, such as minimizing path traveling distance or time interval, lowest energy consumption or obstacle avoidance and satisfying the robot’s kinematics and dynamics. Review, discussion and analysis of optimization techniques to find the optimal trajectory either in Cartesian space or joint space are presented and investigated. Optimal trajectory selection approaches such as kinematics and dynamics techniques with various constraints are presented and explained. Although the kinematics approach is simple and straight forward, it will experience some problems in implementation because of lack of Inertia and torque constraints. The application of Genetic Algorithms to find the optimal trajectory of manipulators especially in the obstacle avoidance is also highlighted. Combining the Genetic Algorithms with other classical optimization methods proves to have better performance as a hybrid optimization technique

Dynamic force/motion simulation of a rigid-flexible manipulator during task constrained

Constrained motion of a rigid-flexible manipulator in contact with a rotating environment is considered. A rigid-flexible manipulator may be assigned tasks in a moving environment where the winds or vibrations affect the position and/or orientation of surface of operation. When the environment is moving, knowledge of the angle a between the contact surface and the horizontal is required at every instant to evaluate the contact force and the rqured torques for a specific atsk. In this paper, different profiles for the time varying angle a are proposed to investigate the interaction between the joints profile and the angular motion of the constrained surface and the effect of this change into the contact force and the joint torques of a rigid-flexible manipulator

Dynamic simulation of task constrained of a rigid-flexible manipulator

A rigid-flexible manipulator may be assigned tasks in a moving environment where the winds or vibrations affect the position and/or orientation of surface of operation. Consequently, losses of the contact and perhaps degradation of the performance may occur as references are changed. When the environment is moving, knowledge of the angle ? between the contact surface and the horizontal is required at every instant. In this paper, different profiles for the time varying angle ? are proposed to investigate the effect of this change into the contact force and the joint torques of a rigid-flexible manipulator. The coefficients of the equation of the proposed rotating surface are changing with time to determine the new X and Y coordinates of the moving surface as the surface rotates

Sensory-based colour sorting automated robotic cell

Robotics application in colour recognition using fiber optic cabled sensors interfaced with robot controller and Programmable Logic Controller (PLC) is discussed in this paper. The sensors send input signals to the robot controller and the specified program will be executed with respect to the triggered input. The aim of this research work is to recognize colour by pin point detection and sorting of object specimens with respect to their colour attributes, which includes hue, saturation and luminance level. The controller programs were designed to control the robot and the conveyor belt independently parallel to each other via relays, to be synchronized during operation. Finally, the calculative results were verified experimentally and the real time implementation was carried out. It can be observed how controllers are integrated and synchronized in a system to perform a desired operation without conflict using real time applications such as chemical, pharmaceutical, agricultural, food industries and even recycling