Control Theory and Technology

, Volume 13, Issue 3, pp 266–285 | Cite as

On the use of positive feedback for improved torque control

  • Houman DallaliEmail author
  • Gustavo A. Medrano-Cerda
  • Michele Focchi
  • Thiago Boaventura
  • Marco Frigerio
  • Claudio Semini
  • Jonas Buchli
  • Darwin G. Caldwell


This paper considers the torque control problem for robots with flexible joints driven by electrical actuators. It is shown that the achievable closed-loop tracking bandwidth using PI torque controllers may be limited due to transmission zeros introduced by the load dynamics. This limitation is overcome by using positive feedback from the load motion in unison with PI torque controllers. The positive feedback is given in terms of load velocity, acceleration and jerk. Stability conditions for designing decentralized PI torque controllers are derived in terms of Routh-Hurwitz criteria. Disturbance rejection properties of the closed system are characterized and an analysis is carried out investigating the use of approximate positive feedback by omitting acceleration and/or jerk signals. The results of this paper are illustrated for a two DoF (degrees of freedom) system. Experimental results for a one DoF system are also included.


Force-torque control load motion compensation decentralized control 


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Copyright information

© South China University of Technology, Academy of Mathematics and Systems Science, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Houman Dallali
    • 1
    Email author
  • Gustavo A. Medrano-Cerda
    • 1
  • Michele Focchi
    • 1
  • Thiago Boaventura
    • 2
  • Marco Frigerio
    • 1
  • Claudio Semini
    • 1
  • Jonas Buchli
    • 2
  • Darwin G. Caldwell
    • 1
  1. 1.Department of Advanced RoboticsIstituto Italiano di Tecnologia (IIT)GenovaItaly
  2. 2.Agile and Dexterous Robotics LabInstitute of Robotics and Intelligent SystemsETH ZürichSwitzerland

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