Estimacíon de la Fuerza de Contacto para el Control de Robots Manipuladores con Movimientos Restringuidos (Contact Force Estimation for Compliant Motion Control)

It is well known that for a robotic manipulator without sensors on the end-effector, the end-effector has to follow a path in its workspace without regard to any feedback other than its joints shaft encoder or resolvers. This fact imposes severe limitations on certain tasks where an interaction between the robot and the environment is needed. However, with the help of sensors, a robot can exhibit an "adaptive behavior", the robot being able to deal flexibly with changes in its environment and to execute complicated skilled tasks. In this paper, we firstly propose a new control strategy based on multisensor fusion with three different sensors-that is, encoders mounted at each joint of the robot with six degrees of freedom, a wrist force sensor and an accelerometer-whose goal is to obtain a suitable contact force estimator for the three Cartesian axes. Secondly, the corresponding self-calibration method developed for the commented contact force observer is also proposed. This procedure aims at offering a `plug-and-play' solution for the integration of different kind of accelerometers with the final goal of obtaining an observer capable of estimating the contact force exerted by an industrial robotic manipulator. To validate both the behaviour of the contact force observer and the performance of the self-calibrating procedure, different experiments were carried out on an ABB industrial robot with open control system architecture. Copyright (C) 2007 CEA-IFAC