Showing papers by "Paolo Rocco published in 2003"
01 Jan 2003
TL;DR: The initial results of a research aimed at investigating to what extent high resolution encoders, which are getting available for common industrial motion control and robotics applications, can be exploited to compensate for non linear friction terms are presented.
Abstract: The initial results of a research aimed at investigating to what extent high resolution encoders, which are getting available for common industrial motion control and robotics applications, can be exploited to compensate for non linear friction terms are presented in this paper. The 22 bits resolution sensor used allowed a neat analysis of the dynamic behavior of friction forces in the presliding regime, and especially of hysteresis loops. A recently proposed friction model has been validated. However, the influence of the cogging torque on the motor has been found to play a key role.
20 citations
20 Jul 2003
TL;DR: In this paper, a simple procedure for identification of the relevant physical parameters, the performance of PID control closed on the motor position is expressed as the H/sub /spl infin// norm of the transfer function from motor position setpoint to load position.
Abstract: PID control closed on the motor position is the most common solution in commercial servomechanisms. If significant compliance exists between the motor and load, performance limitations emerge if the load position behavior is properly considered. Quantification of the loss of performance at increasing nominal bandwidth of the closed loop system is the main result of this paper. After describing a simple procedure for identification of the relevant physical parameters, the performance is expressed as the H/sub /spl infin// norm of the transfer function from motor position setpoint to load position. A simple expression is given and experimentally assessed for this norm, in terms of inertial, elastic and damping parameters of the system, as well as of the nominal bandwidth of the closed loop system. Explicit formulas are finally given for load behavior concerned tuning of the PID controller.
20 citations
20 Jul 2003
TL;DR: In this paper, the visual servoing of eye-in-hand flexible manipulators is considered in a control solution where the two-time scale nature of the problem is exploited.
Abstract: Visual servoing of eye-in-hand flexible manipulators is considered in this paper. Dynamic effects of both the rigid and the flexible motion of the manipulator are fully taken into account in a control solution where the two-time scale nature of the problem is exploited. The visual information is used in the "slow" subsystem for a task space oriented control law, where computationally expensive operations, such as inverse and time derivative of the Jacobian, are avoided. A rigorous proof of stability of this control scheme, based on the Lyapunov theory, is also presented. Some simulation results finally show the effectiveness of the proposed controller.
14 citations
01 Jan 2003
TL;DR: A remote interface for simulating robots via the Internet is presented, dedicated to simulations of robotic arms whose models are written in some descriptive language like Modelica.
Abstract: A remote interface for simulating robots via the Internet is presented. This environment is dedicated to simulations of robotic arms whose models are written in some descriptive language like Modelica. The actual application runs on robot models compiled by Dymola. This work has been developed within a project whose purpose is the Modelica/Dymola implementation of models of space robots and servomechanisms, and their dissemination to partner firms and to the scientific community. The remote simulation environment has been tested with a model of the Spider robotic arm.
8 citations