Single Loop Control

  • Wodek Gawronski
Part of the Mechanical Engineering Series book series (MES)

Control systems of most antennas and radiotelescopes consist of two feedback loops: the velocity and position loops. The velocity feedback is an inner loop that controls motor velocity. The position feedback is an outer loop that controls the antenna position. The questions arise: Is the velocity loop necessary, and for what reason? Is the antenna pointing performance degraded when the velocity feedback is removed? This chapter tries to answer these questions. Simplicity is the reason for the proposed removal of the velocity feedback, because removing the velocity feedback simplifies the hardware, lowers the cost of the antennas, and lowers the cost of their maintenance. A trend toward eliminating the velocity feedback loop is observed in spacecraft and robot control. Recent papers (e.g., [1] and [2]) show that spacecraft can be stabilized and controlled without velocity feedback, and that robots can be controlled without velocity measurements; see [3], [4], [6], and [7].

The analysis...


Transfer Function Velocity Feedback Position Loop Closed Loop Transfer Function Hurwitz Criterion 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. 1.
    Akella MR. (2000). Rigid-Body Attitude Tracking without Angular Velocity Feedback. In: Spaceflight Mechanics 2000, American Astronautical Society, San Diego.Google Scholar
  2. 2.
    Caccavale F, Villani L. (1999). Output Feedback Control for Attitude Tracking. System Control Lett., vol. 38.Google Scholar
  3. 3.
    Chang YC, Chen BS, and Lee TC. (1996). Tracking Control of Flexible Joint Manipulators Using Only Position. Int. J. Control, 64(4).Google Scholar
  4. 4.
    Chang YC, Lee CH. (1999). Robust Tracking Control for Constrained Robots Actuated by DC Motors without Velocity Measurements. IEE Proc. Control Theory and Applications,146(2).Google Scholar
  5. 5.
    Gawronski W. (2002). Single loop Antenna Control. IPN Progress Report 42-151. Available at:
  6. 6.
    Lim SL, Dawson DM, Hu J et al. (1997). An Adaptive Link Position Tracking Controller for Rigid-Link Flexible-Joint Robots without Velocity Measurements. IEEE Trans. System, Man, Cybernetics, Part B: Cybernetics, 27(3).Google Scholar
  7. 7.
    Loria A, Panteley E. (1999). Force/Motion Control of Constrained Manipulators without Velocity Measurements. IEEE Trans. Aut. Control, 44(7).Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Wodek Gawronski
    • 1
  1. 1.California Institute of TechnologyJet Propulsion LaboratoryPasedenaUSA

Personalised recommendations