Applied Mechanics and Materials Vol. 162

Abstract: The purpose of this paper is to observe the ergonomic advantages of different car seats and how the driver is constrained to them during the drive. The study was conducted by taking in to consideration the dynamical characteristics of a standard vehicle and subjecting the human body model provided by the AnyBody Modelling System, to inertia and centrifugal forces, in three different driving posture cases. The model proved to be viable and offered an image of different car seats advantages from ergonomic point of view.

Abstract: The paper presents a complex study on hip joint endoprosthesis. The model for the femur was obtained by CT scanner and Mimics, the endoprosthesis was designed in proEngineer. This study has two stages: obtaining the 3D model for the bone and endoprosthesis, analysing the model in Ansys to obtain stress and strain state information. The paper also presents some interesting aspects of the contact between the bone and the implant in case of different types of endoprosthesis (two standardized types and one personalized). A good contact between the bone and the stem indicates a long life solution for an endoprosthesis. A personalized stem is very useful for persons with disabilities is designed taking in consideration the particularities of the patient. The contact results from Ansys illustrate the aspects from the bone stem interface. With this information the orthopaedist can take better decisions for a proper hip joint endoprosthesis used for a named patient.

Abstract: The paper presents a fatigue analysis of low level links of a parallel topology robot guiding device mechanism. This mechanism has a FP₃+3·RRS+MP₃ structure. The 3D model of the guiding device is presented. In a SolidWorks Motion study, motion laws for motors are defined and a force is applied on the mobile platform MP₃. The loads on low level links are imported in SolidWorks Simulation module. Then, von Mises stresses are determined by finite element method and, based on these results, fatigue analysis is performed. Two variants of low level links are analized: first, with no fillet between the base cylinder and the body and second, with fillet.

Abstract: The paper presents the design of a driving kinematical joint driven by a shape memory alloy actuator, which has the capacity to ensure a control of displacements and of forces in both directions. There are presented some aspects regarding the main designing elements of the driving kinematical joint and of the actuator. The constructive solution, an original conception, presents a series of advantages. Thus, the use of electric, hydraulic or pneumatic engines or machines was eliminated, decreasing the weight and size of the driving kinematical joint, decreasing the energetic consumption, having a simple and viable construction. In order to verify the presented device functionality the numerical simulation method of specialized SolidWorks software was used.

Abstract: In this paper an algebraic formulation is proposed for designing telescopic manipulators when workspace is prescribed in a suitable form. An algorithm has been outlined by using an algebraic formulation for the workspace boundary.

Abstract: The main purpose of the paper is to develop a neural network application destined to the workspace generation of a parallel mechanism, as an performant alternative to the workspace representation based on inverse kinematic model. The paper describes both algorithms. The initial testing was made for a parallel mechanism with two degrees of freedom that could be applied for the orientation of different systems like a TV satellite dish antennas, sun trackers, telescopes, cameras, radars etc.

Abstract: This paper presents a set of techniques based on the use of CAD geometric approaches for singularity surfaces and total operational workspace and joint space determination. The main emphasis is given to the use of CAD tools used to characterize and analyze the performance of planar parallel robot manipulators. The CAD environment provides powerful tools for the graphical programming and geometric feature handling. This paper points out the effectiveness of such a method in the robot design process. These developments are illustrated by the 3-RPR planar parallel manipulator case study. All of the proposed geometric algorithms are implemented in the CATIA CAD environment.

Abstract: This paper deals with the constraint and the singularity analysis of the Exechon. Using the screw theory, the constraint and actuation wrenches acting on the moving platform are analyzed. The motion pattern of the Exechon is characterized based on a representation of the constraint wrenches in the projective space. A wrench graph representing the constraint and actuation wrench systems in the projective space is obtained. Based on this wrench graph, a superbracket of the Exechon is formulated. Finally, this superbracket is explored to provide the geometric conditions for the parallel singularities of the Exechon.

Abstract: In this paper we give a detailed review on Stewart Gough (SG) platforms with self-motions and the related Borel Bricard problem. Moreover, we report about recent results achieved by the author on this topic (SG platforms with type II DM self-motions). In context of these results, we also present two new theorems, which open the way for addressed future work. Finally, we give some remarks on planar SG platforms with type I DM self-motions and formulate a central conjecture.

Abstract: The paper focuses on the calibration of elastostatic parameters of spatial anthropomorphic robots. It proposes a new strategy for optimal selection of the measurement configurations that essentially increases the efficiency of robot calibration. This strategy is based on the concept of the robot test-pose and ensures the best compliance error compensation for the test configuration. The advantages of the proposed approach and its suitability for practical applications are illustrated by numerical examples, which deal with calibration of elastostatic parameters of a 3 degrees of freedom anthropomorphic manipulator with rigid links and compliant actuated joints.