Adaptive variable structure control and applications to friction compensation

FPGA-Based Adaptive Backstepping Sliding-Mode Control for Linear Induction Motor Drive

“…It follows that: (6) Using (6), the desired secondary flux linkage in terms of can be found from (4) as (7) where is the Laplace operator. Moreover, using (3), the feedforward slip velocity signal can be estimated using as shown in (7) and as follows:…”

“…Considering Coulomb friction, viscous friction, and Stribeck effect, the friction force can be formulated as follows [6], [7]: (16) where is the Coulomb friction; is the static friction; is the Stribeck velocity parameter; is the coefficient of viscous friction; and is a sign function. Reformulate (14), then (17) where is called the lumped uncertainty and defined by (18) The lumped uncertainty will be observed by an adaptive uncertainty estimator and assumed to be a constant during the observation.…”

“…In addition, this friction characteristic may be easily varied due to a change in normal forces in contact, and the temperature and humidity. In a closed-loop control system, the friction force results in a steady-state error, a limit cycle, and a low bandwidth [6], [7]. Unfortunately, friction is a natural phenomenon that is quite difficult to model, and it is not completely understood.…”

A genetic algorithm based recurrent fuzzy neural network for linear induction motor servo drive

“…Moreover, uncertainties exist, which are usually composed of unpredictable plant parameter variations, external load disturbance, unmodelled and nonlinear dynamics, in practical applications of the LIM (Takahashi and Ide, 1993;Boldea and Nasar, 1997;Zhang et al, 1995;Bucci et al, 1994;Lin and Lee, 2000;Lin and Wai, 2002a). Furthermore, since the operation of LIM involves two contacting bodies, friction force is inevitably among the forces of motion and results in steady-state error, limit cycle and low bandwidth (Sankaranarayanan and Khorrami, 1997;Maulana et al, 1999). In addition, the friction characteristic may be easily varied due to the change of normal forces in contact, temperature and humidity.…”

Handling stiction with variable structure control

“…The proposed friction model is modular and can be readily used in any application that involves a friction by identifying a few plant dependent parameters. In [21], an adaptive variable structure control methodology is proposed for friction compensation. The friction model as given in [4] is utilized to synthesize a controller around it while the proposed switching controller is designed for a more general class of nonlinear systems of the so-called special strict feedback form which combines the VSC scheme with back-stepping procedure.…”