Papers by Keyword: Parallel Kinematics

Abstract: The increasing use of multi-material constructions lead to a continuous increase in the use of mechanical joining techniques due to the wide range of joining possibilities as well as the high load-bearing capacities of the joints. Nevertheless, the currently rigid tool systems are not able to react to changing boundary conditions, like changing the material-geometry-combination. Therefore research work is crucial with regard to versatile joining systems. In this paper, a new approach for a versatile self-piercing riveting process considering the joining system as well as the auxiliary joining part is presented.

Abstract: This paper covers the kinematics and dynamics modelling of the mechatronic model for a 6 DOF cable-driven parallel robot and derives a real-time capable simulation model for such robots. The governing equations of motion for the platform are derived using Newton-Euler formalism, furthermore, the pulley kinematics of the winches and a linear spring-damper based cable model is introduced. Once the equations of motion are derived, closed-form force distribution is implemented and simulation results of the real-time capable model for the cable-driven parallel robot IPAnema3 are presented. Given the real-time capability, the presented model can be used for hardware-in-the-loop simulation or controller design, but also for case studies of highly dynamic or large-scale robots.

Abstract: The paper presents the structure of a precise parallel tri-axle manipulator with the functionality of progressing-tilting table. The end effector of the device is a platform, for which three coordinates of position are defined. The manipulator has three degrees of freedom: movement perpendicular to the base and rotation in two mutually perpendicular axes contained in the surface parallel to the base.The concept of the positioning mechanism is based on parallel tripod kinematics where the end effector – the platform – is seated on three active limbs – actuators. The use of parallel kinematics allowed modular construction of the positioning mechanism. The developed modular functional mechanism with minimal number of elements in kinematic chain ensures high positioning resolution. The concept of application of eccentric mechanism for platform positioning is an original idea in this solution. The compact construction allows applying the manipulator in medical devices that require meeting of the hygienic conditions in the medical test and research laboratories. The possibility of the utilisation of the precise manipulator covers wide areas of science and technology where precise positioning of the object is required, e.g. sample positioning for microscopes, scanning systems.

Abstract: This paper presents parallel kinematic manipulator design. A manipulator with three axis and parallelogram mechanism was made using aluminium profile rods. This mechanism was controlled by PC with the use of stepper motors. Kinematics analysis was conducted and its findings were used to make a special software to generate G-code control file. X and y mouse cursor indications with given z value were used as data showing the position of the effector to establish the movement of the arms of the presented manipulator. Step2CNC software was used to control the manipulator. Tests have confirmed the correctness of the study.

Abstract: Single point incremental forming has attracted the interest of researchers in the last decade for the production of prototypes and small batch production of sheet-based parts [1, 2]. This technique allows the manufacture of parts without using expensive die sets. The SPIF (Single point incremental forming) process can be performed on different equipments such as adapted CNC milling machines, serial robots and built proposed machines [3]. Every solution has advantages and disadvantages. This work presents the CAD/CAM strategies for a parallel kinematics SPIF machine, designed and built at the University of Aveiro [3]. This machine brings a new approach to the SPIF industry. The machinery used to perform SPIF operations has limitations in their work volume with limited movements and in the magnitude of applicable forces. With that in mind, this machine was projected to overcome that obstacle, and was provided with a system with 6 degrees of freedom, while maintaining the ability to apply high loads. The disadvantage is the increase in volume occupied by the kinematic system. The manufacture of new parts could be reached out with more flexibility on the chosen tool path. The first step is the product design in the commercial CAD system. Next step is generating the tool path of the forming tool. This step is very important to achieve the desired part shape. It is used a commercial CAM system (EdgeCAM 2012®), which has resources from three up to five axis strategies. The last step is to send the information to the machine’s control system, based on real-time software. This paper will describe each step with more details.

Abstract: Though computer technology has brought about virtual manufacturing to expedite design and analysis through simulation and visualization, machines remain essential, as ultimately products need to be made. This paper presents a new type of 5-axis parallel machine tool based on a 3 degrees of freedom parallel platform manipulator with base mounted prismatic actuators. This machine tool is different from the Stewart platform type parallel machine tool in that its feed motion in X-direction is realized by the worktable on which work-piece is fixed and the parallel manipulator sliding on the gantry structure of the machine tool is responsible for the translation along Y-direction instead of the movable platform of the manipulator. Due to this special architecture, the workspace in X-direction and Y-direction of the new machine tool is enlarged greatly. And its rigidity is higher because of the adaptation of gantry structure. This machine tool is controlled by a PC based NC system in simultaneous 5 axes control mode.

Abstract: Single Point Incremental Forming (SPIF) given its easy implementation and absence of dedicated tooling is a promising manufacturing technology concerning the production of customized products, low batches or prototyping of ready-to-use parts. The range of application is wide, covering many materials and virtually unlimited geometries. Indeed, current process boundaries are more related to machine limitations than to the procedure itself. In this paper, research is carried out on the state-of-the-art of existing SPIF machine technology, in order to determine an appropriate configuration for an incremental forming equipment that overcomes such limitations. A comparative analysis is carried out to evaluate the different types of currently used equipment: adapted milling machines, serial robots and purpose built machines. Comparison parameters include among many others the maximum payload, tool path flexibility, stiffness and overall cost of the machine, based on information gathered on publications mainly from the last decade. Alternatively, other solutions used for different technological processes and assembly operations, such as precision positioning, are also taken into account. Based on the comparison of all solutions, and on the objectives of the current project carried out at the University of Aveiro, it is concluded that an equipment with parallel kinematics, driven by hydraulic servo-cylinders, could be the best choice to achieve the established goals.