An improved sliding mode observer is presented to estimate the rotor position of the permanent magnet synchronous motors (PMSMs). In this observer, the discontinuous control is replaced by using the sigmoid function in order to reduce the chattering problem commonly found in the conventional sliding mode observer. When the chattering is reduced, the back emf can be obtained directly from the sw...

This paper addresses the problems caused by an inappropriate selection of sliding surface parameters in fuzzy sliding mode controllers via an optimization approach. In particular, the proposed method employs the parallel distributed compensator scheme to design the state feedback based control law. The controller gains are determined in offline mode via a linear quadratic regular. The particle ...

This paper presents the effects of fixture dynamics on the control of a variable-reluctance spherical motor (VRSM). The cascaded VRSM dynamics has the appropriate structure for the so-called back-stepping controller design method. Implementation of the back-stepping controller, however, requires the computation of the exact motor dynamics at each sampling time. This computational burden has an ...

This paper proposes a new sliding mode controller using neural networks. Multilayer neural networks with the error back-propagation learning algorithm are used to compensate for the system uncertainty in order to reduce the tracking error and control torque. The stability of the proposed control scheme is proved with the Lyapunov function method. Computer simulation shows that the control perfo...

In recent years, underactuated nonlinear dynamic systems trajectory tracking, such as space robots and manipulators with structural flexibility, has become a major field of interest due to the complexity and high computational load of these systems. Hierarchical sliding mode control has been investigated recently for these systems; however, the instability phenomena will possibly occur, especia...

A robust control approach is developed to control robot in the task space using sliding mode by support of feedback linearization control and backstepping method, in this study. The bounds of uncertainties applied in the sliding mode control are reduced by applying feedback linearization. This provides a robust control system with a less error. The back-stepping method is used to define a linea...

This paper proposes a robust output feedback controller for a class of nonlinear systems to track a desired trajectory. Our main goal is to ensure the global input-to-state stability (ISS) property of the tracking error nonlinear dynamics with respect to the unknown structural system uncertainties and external disturbances. Our approach consists of constructing a nonlinear observer to reconstru...

this paper presents a new control scheme for a class of nonlinear systems. in the proposed method, an adaptive neural network observer with rise feedback controller are applied to realize sensorless control scheme. this observer is tuned online and no exact information of nonlinear term of plant is required. so, this characteristic can compensate mismodeling phenomena. also, a new controller ca...

The semi-active suspension system can instantly change the damping coefficient depending in order to ‘stiffen’ or ‘soften’ the system. It will effectively and timely eliminate road disturbances on the car body. Thus, research on the semi-active suspension system is necessary. According to the performance test of the proposed adjustable damper, the different damping coefficients can be selected ...

This paper presents a new nonlinear backstepping controller for a direct-driven permanent magnet synchronous generator-based wind turbine, which is connected to the power system via back-to-back converters. The proposed controller deals with maximum power point tracking (MPPT) in normal condition and enhances the low-voltage ride-through (LVRT) capability in fault conditions. In this method, to...