José M. Jiménez

A simple and general method for kinematic synthesis of spatial mechanisms

In this paper a simple and efficient method for optimum kinematic synthesis of multibody systems is presented. The proposed formulation is based on the use of a set of fully Cartesian coordinates. Using the coordinates, the system is described by a set of geometric constraints and the design requirements are introduced by a set of functional constraints. An objective function is defined and minimized to obtain the values for design parameters. Finally, some planar and three-dimensional examples are presented that illustrate the application of the method.

Dynamic performance of CaPaMan by numerical simulations

In this paper dynamic performance of Cassino parallel manipulator (CaPaMan) has been investigated through numerical simulations by using COMPAMM software. A suitable model has been developed by describing the multi-body system through natural coordinates of suitable points and vectors. A simulation program has been elaborated and several simulations have been carried out for several different movements and feasible applications of CaPaMan. Moreover, a parametric simulation has been carried out in order to investigate the effects of manufacturing tolerance on CaPaMan dynamic behaviour. In particular, frame reactions and actuating torques have been calculated when geometrical dimensions differ from the design values, due to errors in fabrication and assembly of CaPaMan.

Kinematic and Dynamic Simulation of Rigid and Flexible Systems with Fully Cartesian Coordinates

Multibody systems are quite often a complex combination or assembly of mechanical elements with very different mechanical behavior: rigid or flexible, linear or non-linear, etc. Sometimes it can be very difficult to carry out an efficient dynamic simulation with a single software package.

Penalty based Hamiltonian equations for the dynamic analysis of constrained mechanical systems

Abstract We propose in this paper a new penalty based Hamiltonian description of the equations of motion of mechanical systems subject ot both holonomic and non-holonomic constraints. This method shows a clear advantage over the previously proposed acceleration based formulation, in terms of numerical efficiency and constraint stabilization. We also show that the new approach is more efficient and robust than both the Lagranges multiplier method with Baumgarte stabilization, and the use of a minimum set of coordinates. In addition, this new method is robust under singular positions and in the presence of redundant constraints.

Kinematics and Dynamics of a 6-RUS Hunt-Type Parallel Manipulator by Using Natural Coordinates

In this paper the kinematics, (position, velocities and accelerations) and the dynamics of a 6-RUS parallel manipulator by using the natural coordinates are analysed. One numerical example of kinematics and inverse dynamics is presented.

High Performance Computing in Multibody System Design

This paper presents recent developments of high performance computing and networking techniques in the field of computer-aided multibody analysis and design. The authors describe the main achievements obtained in the development of a tool to aid in the design of new industrial mechanical systems by performing parallel parametric multibody simulations. The parallel software is composed of four main modules: two user-friendly interfaces to input the data and visualize the results, a simulation module, and a parallel manager module that is the main focus of this paper. The authors show that the implementation, using PVM, of simple and well-known ideas leads to efficient and flexible parallel software targeted for heterogeneous networks of nondedicated workstations, which is the parallel platform available in most mechanical design departments. The authors also describe the main features of this module that implements, for the sake of efficiency and robustness, a load-balancing strategy and fault tolerance capabilities. One of the main results of this development has been to demonstrate that high performance computing can sometimes be easily and efficiently introduced into industrial companies without requiring major investments. Pictures of the user interfaces are depicted to illustrate the usability of the parallel software. Performance observed on single and multiprocessor workstation networks is given to assess the relevance of using high performance computing techniques in an industrial environment for the design of mechanical systems.

High Performance Computing for Optimum Design of Multi-body Systems

This paper presents the most relevant results of ODESIM project, a High Performance Computing and Networking project funded by the European Commission within ESPRIT programme. The project acronym stands for Optimum DESIgn of Multi-body systems. The project main objective has been the development of a set of software tools for the kinematic and dynamic optimum design of multi-body systems. Several types of design procedures are targeted: interactive design, designer-driven optimization and fully automatic optimization. ODESIM has been implemented using high performance computing and networking techniques (HPCN) to perform parallel computations in the most CPU-intensive optimization problems. Results on the solution of practical problems are presented.

Parametric Simulation of Multi-body Systems on Networks of Heterogeneous Computers

This paper presents an overview of the software tools developed in the framework of HIPERCOMBATS and MYSHANET projects. These are High Performance Computing and Networking (HPCN) projects funded by the European Commission in the frame of the CAPRI initiative and the Technology Transfer Nodes (TTN) initiative, respectively. These tools are aimed at helping the engineers in the complex task of designing new multi-body systems. The main objective of both projects has been the development of software tools that allow the designer performing parametric simulations on a nondedicated network of heterogeneous computers. The simulations are performed concurrently by the parallel task manager module. Finally, an interactive post-processor allows the users to have an easy access to the computed results.

HIPERCOMBATS: A Parallel Industrial Tool for Two-Wheeler Suspensions Design

In this paper we present an overview of the HPCN tool developed in the framework of the CAPRIs subproject HIPERCOMBATS (Esprit — HPCN contract no EP-9602 CAPRI). The acronym HIPERCOMBATS states for HIgh PERformance COmputing in Multi-Body Analyis for Two-wheeler Suspension design. This tool aims at helping the design of new suspensions for two wheeler vehicles by performing parametric simulations on a non dedicated network of heterogeneous computers, that is the parallel platforms available at PIAGGIO V.E. The user interacts with the code through a pre-processor and a post-processor. The user friendly pre-processor has been designed to allow the user to input each of the physical quantities characterizing the vehicle dynamics and to define the set of computers he intends to use for the parametric study. The Multi-Body System (MBS) simulations, using a general purpose MBS package called COMPAMM [2], are performed concurrently and are driven by a Parallel Manager module. The post-processor permits the users to have an easy access to the results by plotting the quantities meaningful for the study. Pictures of these user interfaces will be given in this paper as well as parallel performance.