Recursive and Symbolic Calculation of the Elastodynamic Model of Flexible Parallel Robots

International audienceThis paper presents a symbolic and recursive calculation of the elastodynamic model of flexible parallel robots. In order to reduce the computational time required for simulating the elastodynamic behavior of robots, it is necessary to minimize the number of operators in the symbolic expression of the model. Some algorithms have been proposed for the rigid case, for parallel robots with lumped springs or for serial robots with distributed flexibilities. In this paper, we extend the previous works to parallel robots with distributed flexibilities. The generalized Newton-Euler model is used and combined with the principle of virtual powers to minimize the number of operators and intermediate variables. Recursive calculations are proposed for the computation of the Jacobian matrices defining the kinematic constraints in order to decrease the number of operators. The proposed algorithm is used to compute the elastodynamic model of a prototype of a planar parallel robot developed at IRCCyN: the DualEMPS. The computed model is compared both with simulations done on Adams and with experiments. The validity of the approach in terms of result accuracy and computational time is demonstrated

SYMORO+: A SYSTEM FOR THE SYMBOLIC MODELLING OF ROBOTS

International audienceThis paper presents the software package SYMORO+ for the automatic symbolic modelling of robots. This package permits to generate the direct geometric model, the inverse geometric model, the direct kinematic model, the inverse kinematic model, the dynamic model, and the inertial parameters identification models. The structure of the robots can be serial, tree structure or containing closed loops. The package runs on Sun stations and PC computers, it has been developed under MATHEMATICA and C language. In this paper we give an overview of the algorithms used in the different models, the computational cost of the dynamic models of the PUMA robot are given

GECARO: A system for the GEometric CAlibration of RObots

International audienceThis paper presents a software package for the simulation and the practical calibration of the geometric parameters of robots. This system which is called GECARO, GEometric CAlibration of RObots, contains a large variety of methods to identify the geometric parameters of robots. GECARO is running on PC computers and developed using MATLAB; any general serial robot can be treated directly. The identifiable parameters are determined using a numerical method based on the QR decomposition, while the identification is carried out using linearized model which is solved iteratively using least squares criterion and by updating the observation matrix after each iteration

Robot Manipulators: Modeling, Performance Analysis and Control

International audienceThis book presents the most recent research results about the modeling and control of robot manipulators. - Chapter 1 gives unified tools to derive direct and inverse geometric, kinematic and dynamic models of serial robots and addresses the issue of identification of the geometric and dynamic parameters of these models. - Chapter 2 describes the main features of parallel robots, the different architectures and the methods used to obtain direct and inverse geometric, kinematic and dynamic models paying special attention to singularity analysis. - Chapter 3 introduces global and local tools for performance analysis of serial robots. - Chapter 4 presents an original optimization technique for point-to-point trajectory generation accounting for the robot dynamics. - Chapter 5 presents standard control techniques in the joint space and task space for free motion (PID, computed torque, adaptive dynamic control, and variable structure control), and constrained motion (compliant force-position control). - In chapter 6, the concept of vision-based control is developed and Chapter 7 is devoted to specific issue of robots with flexible links. Efficient recursive Newton-Euler algorithms for both inverse and direct modeling are presented, as well as control methods ensuring position setting and vibration damping

Recursive Symbolic Calculation of the Dynamic Model of Flexible Parallel Robots

International audienceThis paper presents a symbolic and recursive calculation of the dynamic model of flexible parallel robots. In order to reduce the computational time, it is necessary to minimize the number of operators in the symbolic expression of the model. Some algorithms have been proposed for the rigid case, for parallel robots with lumped springs or for serial robots with distributed flexibilities, but to the best of our knowledge, nothing has been developed for parallel robots with distributed flexibilities. This paper aims at filling this gap. In order to minimize the number of operations, the Newton-Euler principle is used and combined with the principle of virtual powers. The Jacobian matrices defining the kinematic constraints are computed using recursive calculations that decrease the number of operators. The proposed algorithm is used to compute the elastodynamic model of a planar parallel robot. The obtained results, compared with those obtained with commercial softwares, show the validity of the proposed algorithm

Macro-continuous computed torque algorithm for a three-dimensional eel-like robot

International audienceThis paper presents the dynamic modeling of a continuous three-dimensional swimming eel-like robot. The modeling approach is based on the "geometrically exact beam theory" and on that of Newton-Euler, as it is well known within the robotics community. The proposed algorithm allows us to compute the robot's Galilean movement and the control torques as a function of the expected internal deformation of the eel's body

Identification of the Dynamic Parameters of the Orthoglide

International audienceThis paper presents the experimental identification of the dynamic parameters of the Orthoglide [1], a 3-DOF parallel. The dynamic identification model is based on the inverse dynamic model, which is linear in the parameters. The model is computed in a closed form in terms of the Cartesian dynamic model elements of the legs and of the Newton-Euler equation of the platform. The base inertial parameters of the robot, which constitute the identifiable parameters, are given

Identification experimentale des paramètres inertiels de la charge d'un robot Stäubli RX90

International audienceDans cet article nous présentons l'identification des paramètres inertiels de la charge d'un robot Stäubli RX 90. La connaissance de ces paramètres peut être utilisée pour mettre à jour le réglage de la commande afin d'améliorer la précision du robot, et pour la vérification de la masse transportée. L'expérimentation a été faite en utilisant le contrôleur Stäubli (version CS8) qui permet d'avoir accès aux positions, vitesses et couples articulaires. Nous présentons quatre modèles d'identification linéaires par rapport aux paramètres dynamiques afin d'identifier les paramètres inertiels de la charge. La solution revient alors à résoudre un système linéaire surdéterminé au sens des moindres carrés

Modelling and Simulation of a Two wheeled vehicle with suspensions by using Robotic Formalism

International audienceModels, simulators and control strategies are required tools for the conception of secure and comfortable vehicles. The aim of this paper is to present an efficient way to develop models for dynamic vehicle, focusing on a two wheeled vehicles whose body involves six degrees of freedom. The resulting model is sufficiently generic to perform simulation of realistic cornering and accelerating behavior in various situations. It may be used in the context of motorcycle modeling, but also in various situations (e.g. for control application) as simplified model for 3 or 4 wheeled (tilting) cars. The approach is based on considering the vehicle as a multi-body poly-articulated system and the modeling is carried out using the robotics formalism based on the modified Denavit-Hartenberg geometric description. In that way, the dynamic model is easy to implement and the system can be used for control applications

Geometric Model of a Narrow Tilting CAR using Robotics formalism

International audienceThe use of an Electrical narrow tilting car instead of a large gasoline car should dramatically decrease traffic congestion, pollution and parking problem. The aim of this paper is to give a unique presentation of the geometric modeling issue of a new narrow tilting car. The modeling is based on the modified Denavit Hartenberg geometric description, which is commonly used in Robotics. Also, we describe the special Kinematic of the vehicle and give a method to analyze the tilting mechanism of it. Primarily experimental results on the validation of the geometrical model of a real tilting car are given