A novel Shape Memory Alloy (SMA) actuator consisting of several thin NiTi bers woven in a counter rotating helical pattern around supporting disks is rst described. This structure accomplishes a highly e cient transformation between force and displacement overcoming the main mechanical drawback of shape memory alloys, that being limited strain. Time domain open loop experiments were then conduc...

This brief paper proposes a method for tuning the parameters of a variable structure controller. The approach presented extracts the error at the output of the controller and applies a nonlinear tuning law using this error measure. The adaptation mechanism drives the state tracking error vector to the sliding hypersurface and maintains the sliding mode. In the simulations, the approach presente...

A new approach to control system design for systems containing uncertain, nonsmooth friction is proposed. The method is based on a multi-state backstepping approach to variable structure control design. Stability and robustness properties are investigated and an example is given.

An adaptive fuzzy sliding mode control scheme is presented in this article. Despite the advantages of sliding mode control design for uncertain dynamic systems, classical sliding mode control has a major problem in the form of chattering, produced by the rapid switching used to conduct the state trajectories toward the sliding surfaces. A variety of methods are used to achieve chattering-free m...

A variable-structure control system designed to enable a fuselage-heavy airplane to recover from spin has been demonstrated in a hand-launched, instrumented model glider airplane (see figure). It has long been known that the most effective spin recovery technique for fuselage-heavy aircraft involves the use of ailerons to roll the airplane into the spin. This technique might be considered count...

In this article, regulation of a distributed-parameter flexible beam is considered using variable structure control techniques. The proposed controller can stabilize the system exponentially and the converging speed can be set by the designer as desired. Different from existing variable structure controllers for flexible robots in the literature, the controller presented here is designed direct...

Torque and speed sensorless induction motor control is presented in this paper. The idea is realized using a sliding mode closed loop rotor flux observer for estimation of electromotive force of machine. This signal is then used in nonlinear stator flux and torque control of induction motor and in rotor flux observer for speed and flux estimation. The analysis of the proposed method is included...

An adaptive variable structure position control for induction motors using field oriented control theory is presented. The proposed sliding-mode control law incorporates an adaptive switching gain to avoid calculating an upper limit of the system uncertainties. The design incorporates a flux estimator that operates on the principle of flux and current observer. The proposed observer is basicall...