No description available.

No description available.

Industrial robots and automation technology have advanced rapidly in the last several decades. New types of manipulators that uses parallel mechanisms are becoming more popular due to their high speed and high stiffness. This thesis focuses on a sub-class of parallel manipulators that uses cables to replace rigid links for further increase in speed. The design strategies in this study were expanded from research works by Khajepour. Behzadipour, and Edmon Chan. This thesis presents analysis and development of a new cable-based planar parallel manipulator that is based on a previous prototype built by Edmon Chan. The new manipulator design added a new rotational DOF to the end-effector, and the number of cables are doubled in order to increase the stiffness. New methods for kinematics and dynamics analysis are formulated to make the procedure more systematic. A new mathematical formulation for stiffness matrix of the end-effector is presented. The resultant stiffness matrix is equivalent to the stiffness matrix formulated by Behzadipour. Additional stiffness analysis is conducted on valid range of stiffness calculation and comparison of different cable configurations. A multi-objective optimization problem is formulated in order to search for the best set of design parameters for the manipulator, and it is solved with an exhaustive complete search method. A physical prototype of the manipulator is modelled and manufactured with the help of partners from Conestoga college. Experiments with the manipulator show that more powerful motors are needed to run the robot at full speed. Motor torque measurements show that the dynamics analysis of the manipulator is valid. Stiffness of the manipulator is measured by applying external force to the end-effector, and it is shown to be strong. The manipulator is able to demonstrate a sort and pick-and-place operation at 60 cycles per minute while running at 70% of the maximum speed, with an acceleration of 2.8 g and velocity of 4 m/s.

Zugl.: Stuttgart, Universiẗat, Diss. 2007.

Parallel mechanisms are characterized by their kinematic structure presented a closed kinematic chain. The end effector of mechanism is then bound to a base of over one arm. This design provides an advantage especially at high stiffness of mechanism and related properties. The disadvantage of such a structure is then usually very limited working space. In terms of simulation modeling is the construction due to its complexity rather problematic. The aim of work is design comprehensive simulation model chosen parallel mechanism and its analysis in selected working modes. Expected to use Adams simulation environment, if necessary. Matlab - SimMechanics and Ansys.

The development of new techniques for control of magnetic objects by external magnetic fields has been in constant improvement. These advancements range from the design and fabrication of magnetic nanoparticles to design and control of actuators that enable their manipulation. The ability to guide such magnetic objects at a distance without any direct mechanical contact is an attractive feature with great potential in medical applications. Magnetic fields are not distorted by their interaction with nonmagnetic materials, like those in the human body; and pose no harm to living tissues, which make them convenient tools for minimally invasive techniques and treatments. Moreover, several actuator configurations have been proposed to achieve the remote motion of a magnetic particle or magnetic fluids. Arrays of electromagnets have been widely utilized due to their lack of mechanical parts and flexibility to accurately and rapidly change their magnetic field by controlling the current through their coils. However, they are relatively weak for their size and electrical power, making them inefficient for medical applications which need large magnetic forces at relatively long distances. On the other hand, permanent magnets have a much higher strength-to-size ratio than electromagnets and allow for control from larger distances. The disadvantage is that their magnetic fields cannot be turned off and a mechanical actuator is needed to modify their position and orientation to change their field. In this work, a magnetic manipulator used as a testbed to manipulate a magnetic bead is designed. It consists of an array of six diametrically magnetized cylindrical permanent magnets evenly spaced around a petri dish, following the work in [11]. Servomotors are utilized to precisely adjust the direction of the magnets according to a control law developed by other researchers in the past. A monochromatic camera located above the petri dish provides the feedback on the position of the bead and a set of hall-effect sensors provides the location of the poles of the magnets. The dynamics of the system is modeled by a linearized set of state-space equations where the magnetic field is estimated with an analytical expression for the geometry of the magnets. The testbed has been designed with the CAD software SolidWorks and its structure has been completely 3D printed with polylactic acid (PLA) filament. The design is tested under different speeds of the servomotors and initial orientations of the magnets. Some recommendations are presented at the end for improvement and considerations for future designs.

No description available.

This thesis investigates the strengths and weaknesses of omnidirectional drive and differential drive systems on mobile manipulator robots. Based on a literature study, a hypothetical use case, and identified Key Performace Indicators the drive system’s effects on the performance of the mobile manipulator are evaluated. A qualitative approach was used for evaluation. The research methodology involved analyzing the wheel characteristics of each drive system, identifying parameters affecting the performance, and assessing the two drive system characteristics within the context of the hypothetical use case. Six Key Performance Indicators such as pose accuracy, space utilization, and manipulability were formulated and examined to determine the comparative strengths and weaknesses of the drive systems. The results confirmed that omnidirectional drive systems exhibit greater maneuverability and agility while differential drive systems are less complex and often more durable in rough conditions. However, the results also show that in many cases the answer on what drive system to use will depend on many factors and that these factors can affect the overall performance of the mobile manipulator. This study provides insights into performance-affecting parameters and relevant performance aspects by examining the strengths and weaknesses of omnidirectional and differential drive systems. While acknowledging the need for caution in generalizing the findings and assuming validity in real-world applications, the results obtained serve as a starting point for further investigations. / Detta examensarbete undersöker styrkor och svagheter hos omnidirektionella drivsystem och differentialdrivsystem på mobila manipulatorer. En kvalitativ metod, baserat på en litteraturstudie, ett hypotetiskt användningsscenario och identifierade prestationsindikatorer, användes för att utvärdera drivsystemets effekter på den mobila manipulatorns prestanda. Forskningsmetodiken innebar att analysera hjulegenskaperna för varje drivsystem, identifiera parametrar som påverkar prestandan och bedöma de två drivsystemens egenskaper inom ramen för det hypotetiska användningsfallet. Viktiga prestationsindikatorer som poserings noggrannhet, utrymmesutnyttjande och manipulerbarhet undersöktes för att fastställa och jämförande styrkorna och svagheterna hos drivsystemen. Resultaten bekräftade att omnidirektionella drivsystem uppvisar större manövrerbarhet och smidighet medan differentialdrivsystem ofta är mindre komplexa och mer hållbara under tuffa förhållanden. Dock visar resultaten även att svaret på vilket drivsystem som ska användas i många fall beror på flertalet faktorer och att dessa faktorer kan påverka den mobila manipulatorns totala prestanda. Denna studie ger insikter i prestandapåverkande parametrar och relevanta prestandaaspekter genom att undersöka styrkorna och svagheterna hos omnidirektionella och differentiella drivsystem. Samtidigt som man erkänner behovet av försiktighet med att generalisera resultaten och anta giltighet i verkliga tillämpningar, tjänar de erhållna resultaten som en utgångspunkt för ytterligare undersökningar.

No description available.

Redundant manipulators are widely used because they have a greater dexterity andversatility than nonredundant manipulators. In the redundant manipulators, thenumber of degrees of freedom are more than the required to manipulate objects atthe task space, which leads to a possibility to generate infinite number of solutions.For this reasons it has been a hot research topic to exploit the redundancy. Thisthesis work is focus on modeling and controlling redundant robot manipulator withseven degree of freedom (LWA 10 kg payload by Schunk). A literature review hasbeen prepared on the existing methods of exploiting the redundancy in the 7-DOFmanipulators at the velocity and position levels. The forward kinematic equationsare derived using the Denavit-Hartenberg method. The inverse kinematic problem issolved and the redundancy is exploited at the position level to avoid the computationalcomplexity and inaccuracy associated with exploiting the redundancy at the velocitylevel. The joint angles of the manipulator are computed in term of a redundancyparameter defining the self-motion in the manipulator. The relation between the jointangles and the redundancy parameter is exploited to avoid selecting the arm anglesthat violate the joint limits. The singularity configurations and robot workspace arealso studied in this thesis. An example is presented on how the self-motion of thearm appears when the end-effector is stationary. The methods are applied to followstraight line trajectories while preventing the joints to exceed the limits. The resultsfound showed how exploiting the redundancy at the position level is being exact withlow computational cost. The validity of the methods is verified by Robotics Toolboxsimulations.