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.

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.

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.

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This thesis presents two unique micro-motion parallel kinematic manipulators (PKM): a three degrees of freedom (3-DOF) micro-motion manipulator and a 3-DOF micro-motion manipulator with actuation redundancy. The 3-DOF micro-motion manipulator has three linear-motion driving units, and the 3-DOF micro-motion manipulator with redundancy has four of these units. For both designs, the linear motion driving units are identical, and both machines have a passive link in the center of the structure. The purpose of this passive link is to restrain the movement of the manipulator and to improve the stiffness of the structure. As a result, both structures support 3-DOF, including one translation on the Z-axis and two rotations around the X and Y axes. The manipulator with redundancy is designed to prevent singularity and to improve stiffness. In this thesis, the inverse kinematic, Jacobian matrix and stiffness analyses have been conducted, followed by the design optimization for structures. Finally, the FEA (Finite Element Analysis) and dynamic analysis have also been performed. There are many practical applications for micro-motion parallel manipulators. The typical applications include micro-machine assembly, biological cell operation, and microsurgery . / UOIT

The thesis acquaints the reader with issues of manipulators based on parallel kinematic structures. It includes also the description of the construction procedure of chosen mechanism. Introductory search part specifies selected terms relating to building elements and describes their requirements. Alternatives of construction and used types of manipulators are shown in the illustrative images with labels. Next chapters deal with projects of selected parallel mechanism and methodologies of constructions. These chapters describe the design of all devised construction nodes. The construction and testing of the produced prototype is properly documented, indicating the resulting knowledge.

No description available.

Redundantly actuated manipulators have only recently aroused significant scientific interest. Their advantages in terms of enlarged workspace, higher payload ratio and better manipulability with respect to non-redundantly actuated systems explain the appearance of numerous applications in various fields: high-precision machining, fault-tolerant manipulators, transport and outer-space applications, surgical operation assistance, etc. The present Ph.D. research proposes a unified approach for modeling and actuation of redundantly actuated parallel manipulators. The approach takes advantage of the actuator redundancy principles and thus allows for following trajectories that contain parallel (force) singularities, and for eliminating the negative effect of the latter. As a first step of the approach, parallel manipulator kinematic and dynamic models are generated and treated in such a way that they do not suffer from kinematic loop closure numeric problems. Using symbolic models based on the multibody formalism and a Newton-Euler recursive computation scheme, faster-than-real-time computer simulations can thus be achieved. Further, an original piecewise actuation strategy is applied to the manipulators in order to eliminate singularity effects during their motion. Depending on the manipulator and the trajectories to be followed, this strategy results in non-redundant or redundant actuation solutions that satisfy actuator performance limits and additional optimality criteria. Finally, a validation of the theoretical results and the redundant actuation benefits is performed on the basis of well-known control algorithms applied on two parallel manipulators of different complexity. This is done both by means of computer simulations and experimental runs on a prototype designed at the Center for Research in Mechatronics of the UCL. The advantages of the actuator redundancy of parallel manipulators with respect to the elimination of singularity effects during motion and the actuator load optimization are thus confirmed (virtually and experimentally) and highlighted thanks to the proposed approach for modeling, simulation and control.

Manipuladores paralelos são aqueles que possuem mais de uma cadeia cinemática que liga a base ao efetuador final. Esta característica proporciona vantagens sobre os manipuladores em série, como maior robustez, maior carga útil e maior velocidade. Por outro lado, as singularidades presentes nos manipuladores paralelos diminuem a área de trabalho prejudicando o desempenho dos mesmos. Uma técnica para evitar as singularidades é a redundância cinemática, que consiste em adicionar atuadores às cadeias cinemáticas possibilitando a reconfiguração do manipulador. Além disso, a redundância cinemática pode melhorar também a rigidez, a robustez, a precisão do sistema, entre outras características, provando ser uma boa alternativa para melhorar o desempenho de manipuladores. Entretanto, alguns dos problemas encontrados em manipuladores paralelos com níveis de redundância altos são os modelos com dinâmica acoplada, que dificultam a implementação de simulações, e o controle ainda mais complexo do que manipuladores paralelos não redundantes. Portanto, esta tese apresenta um estudo sobre o controle de um manipulador paralelo versátil redundante e o impacto dos níveis de redundância cinemática sobre seu desempenho dinâmico. O protótipo consiste de um manipulador paralelo planar atuado por três motores rotacionais e três guias lineares acionadas por motores rotacionais. O acionamento ou não do movimento da guia linear define a redundância do sistema garantindo a versatilidade do protótipo, que pode apresentar de nenhum a três níveis de redundância cinemática. Essa variação permite a avaliação do impacto de diferentes níveis de redundância cinemática no manipulador. Além disso, dois controles baseados no modelo do manipulador, o controle torque calculado e o controle com linearização por retroalimentação, foram implementados para minimizar o impacto da dinâmica acoplada e não linearidades. Estes controles foram comparados com um controle tradicional como referência de comparação. Os resultados demonstraram que o desempenho do manipulador é melhorado utilizando três níveis de redundância e o controle torque calculado em termos de erro de posição e torques executados. / Parallel manipulators are those that have more than one kinematic chain linking the base to the end-effector. This feature provides advantages over serial manipulators, such as greater robustness, higher payload and higher speed. On the other hand, the singularities present in the parallel manipulators decrease the workspace and impair their performance. One technique to avoid the singularities is the kinematic redundancy, which consists of adding actuators to the kinematic chains allowing the reconfiguration of the manipulator. In addition, kinematic redundancy can also improve stiffness, robustness, accuracy, and other features proving to be a good alternative to improve the performance of manipulators. However, some of the problems encountered in parallel manipulators with high levels of redundancy are models with coupled dynamics, that hamper simulations, and even more complex control than non-redundant parallel manipulators. Therefore, this thesis presents a study on the control of a versatile redundant parallel manipulator and the impact of kinematic redundancy levels on its dynamic performance. The prototype consists of a parallel planar manipulator actuated by three rotational motors and three linear guides driven by rotational motors. Whether or not linear motion is triggered defines the redundancy of the robotic system, ensuring the versatility of the prototype, which can vary from no to three levels of kinematic redundancy. This variation allows the impact evaluation of different levels of kinematic redundancy in the manipulator. In addition, two controls based on the manipulator model, the computed torque control and the feedback linearization control were implemented to minimize the impact of coupled dynamics and nonlinearities. These controls were compared with a traditional control as reference. The results demonstrated that the manipulator performance is improved by using three levels of redundancy and the computed torque control in terms of position error and executed torques.

Parallel manipulators have been the subject of study of much robotic research during the past three decades. A parallel manipulator typically consists of a moving platform that is connected to a fixed base by at least two kinematic chains in parallel. Parallel manipulators can provide several attractive advantages over their serial counterpart in terms of high stiffness, high accuracy, and low inertia, which enable them to become viable alternatives for wide applications. But parallel manipulators also have some disadvantages, such as complex forward kinematics, small workspace, complicated structures, and a high cost. To overcome the above shortcomings, progress on the development of parallel manipulators with less than 6-DOF has been accelerated. However, most of presented parallel manipulators have coupled motion between the position and orientation of the end-effector. Therefore, the kinematic model is complex and the manipulator is difficult to control. Only recently, research on parallel manipulators with less than six degrees of freedom has been leaning toward the decoupling of the position and orientation of the end-effector, and this has really interested scientists in the area of parallel robotics. Kinematic decoupling for a parallel manipulator is that one motion of the up-platform only corresponds to input of one leg or one group of legs. And the input cannot produce other motions. Nevertheless, to date, the number of real applications of decoupled motion actuated parallel manipulators is still quite limited. This is partially because effective development strategies of such types of closed-loop structures are not so obvious. In addition, it is very difficult to design mechanisms with complete decoupling, but it is possible for fewer DOF parallel manipulators. To realize kinematic decoupling, the parallel manipulators are needed to possess special structures; therefore, investigating a parallel manipulator with decoupling motion remains a challenging task. This thesis deals with lower mobility parallel manipulator with decoupled motions. A novel parallel manipulator is proposed in this thesis. The manipulator consists of a moving platform that is connecting to a fixed base by three legs. Each leg is made of one C (cylinder), one R (revolute) and one U (universal) joints. The mobility of the manipulator and structure of the inactive joint are analyzed. Kinematics of the manipulator including inverse and forward kinematics, velocity equation, kinematic singularities, and stiffness are studied. The workspace of the parallel manipulator is examined. A design optimization is conducted with the prescribed workspace. It has been found that due to the special arrangement of the legs and joints, this parallel manipulator performs three translational degrees of freedom with decoupled motions, and is fully isotropic. This advantage has great potential for machine tools and Coordinate Measuring Machine (CMM). / UOIT