Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
IMPEDANCE CONTROL FOR ASSISTANCE IN CARGO HANDLING
Submission Author:
Fabrizio Leonardi , SP , Brazil
Co-Authors:
Samuel Monteiro , Sergio Delijaicov, Marko Ackermann, Fabrizio Leonardi
Presenter: Fabrizio Leonardi
doi://10.26678/ABCM.COBEM2017.COB17-0645
Abstract
Power assisted systems can be used to overcome problems associated with manual cargo handling, such as injuries and muscle fatigue. This paper proposes the design of an impedance control system applied to a human-driven cargo cart by means of an electric motor to assist the operator. The control system aims at establishing the dynamic relationship between the applied force and the cart velocity, i.e. imposing a desired apparent mechanical impedance. The proposed methodology was inspired by the feedback linearization technique to promote an apparent change in mass and viscous friction coefficient of the system. It is shown that, with this technique, one can obtain an impedance control without the use of force sensors. For the experiments, a lab scale set of motor and tach generator is adopted. The controller requires information on angular velocity and acceleration, but only the velocity is measured directly, with a numerically estimated acceleration. The proposed control law generates additional terms in the differential equation to change system dynamics, also allowing compensation of Coulomb friction. To validate the results, a load cell was used which served to compare the prescribed impedance with the actual impedance of the system. In this validation process, it was observed that in all imposed impedance conditions whose control effort was below the actuator’s saturation limit, the experimental impedance were very close to the prescribed impedance.
Keywords
Impedance Control, DC Motor, Robotics, Power assisted wheelchair
