Autobalancing DCAL controller for a rotating unbalanced disk q B.T. Costic a, * , S.P. Nagarkatti c , D.M. Dawson a , M.S. de Queiroz b a Department of Electrical and Computer Engineering, Clemson University, Clemson, SC 29634-0915, USA b Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA 70803-6413, USA c Lucent Technologies, Optical Fiber Solutions, Sturbridge, MA 01566, USA Received 28 February 2000; accepted 6 February 2001 Abstract In this paper, we design a control strategy for a rotating, unbalanced disk. The control strategy, which is composed of a control torque and two control forces, regulates the disk displacement and ensures angular velocity tracking. The controller uses a desired compen- sation adaptation law and a gain adjusted forgetting factor to achieve exponential stability despite the lack of knowledge of the imbalance-related parameters, provided a mild persis- tency of excitation condition is satisfied. Ó 2002 Elsevier Science Ltd. All rights reserved. 1. Introduction A perfectly balanced rotating object (i.e., the center of geometry and center of mass are coincident) will usually not undergo any vibration; however, due to the errors associated with geometric dimensions and the non-homogeneity of the raw material, the construction of a perfectly balanced object is difficult to achieve using a standard manufacturing process. Since it is difficult or expensive to construct a perfectly balanced object, one can expect some amount of vibration as the object rotates. This vibration can lead to performance degradation and/or failure of the Mechatronics 12 (2002) 685–712 q This work is supported in part by the US National Science Foundation Grants DMI-9457967, CMS- 9634796, ECS-9619785, NASA Grant NGT-1052611, DOE Grant DE-FG07-96ER14728, the Square D Corporation, and the Union Camp Corporation. * Corresponding author. Fax: +1-864-656-7218. E-mail addresses: bcostic@ces.clemson.edu (B.T. Costic), snagark@lucent.com (S.P. Nagarkatti), ddawson@ces.clemson.edu (D.M. Dawson), dequeiroz@me.lsu.edu (M.S. de Queiroz). 0957-4158/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0957-4158(01)00021-6