The paper presents a new parallel micromanipulator that is composed of three piezohydraulic actuation systems. The basic elements of the actuation system are a piezoelectric actuator, a bellows and hydraulic oil. The use of the flexible bellows results in a new type of parallel structure, where the joints are integrated into actuator links. The joint-free tripod-like micromanipulator is control...

This paper presents an adaptive iterative learning control scheme that is applicable to a class of nonlinear systems. The control scheme guarantees system stability and boundedness by using the feedback controller coupled with the fuzzy compensator and achieves precise tracking by using the iterative learning rules. In the feedback plus fuzzy compensator unit, the feedback control part stabiliz...

Definition Nonlinear control systems are those control systems where nonlinearity plays a significant role, either in the controlled process (plant) or in the controller itself. Nonlinear plants arise naturally in numerous engineering and natural systems, including mechanical and biological systems, aerospace and automotive control, industrial process control, and many others. Nonlinear control...

Activated sludge wastewater treatment processes are difficult to be controlled because of their complex and nonlinear behavior; however, the control of the dissolved oxygen and nitrogen levels in the reactors plays an important role in the operation of the facility. For this reason a new approach is proposed in this work. The paper describes the theory and applications of a nonlinear control te...

In this paper, sufficient criteria for the existence of multiple positive periodic solutions of a certain nonlinear dynamic system with feedback control are established. This is done by the Avery–Henderson fixed point theorem and the Leggett– Williams fixed point theorem. By using the method of coincidence degree, sufficient conditions are derived ensuring the existence of at least one periodic...

The paper studies the problem of nonlinear feedback control design of non-isothermal Continuously Stirred Tank Reactors (CSTR). The objective is to construct a feedback controller such that a desired equilibrium of the closed-loop dynamic is asymptotically stable and such that the closed-loop vector field is a conservative vector field of a particular type, i.e., a gradient system. Properties o...

In this paper, an adaptive fuzzy control scheme is proposed for a class of perturbed strict-feedback nonlinear systems with unknown discrete and distributed time-varying delays, and the proposed design method does not require a priori knowledge of the signs of the control gains.Based on the backstepping technique, the adaptive fuzzy controller is constructed. The main contributions of the paper...

This paper presents a brief study on the design and performance comparison of conventional first-order and super-twisting second-order sliding mode observers for some nonlinear control systems. Estimation accuracy, fast response, chattering effect, peaking phenomenon and robustness are considered for nonlinear systems under observer-based output feedback control and state feedback control.

Nonlinear Model Predictive Control (NMPC), generally based on nonlinear state space models, needs knowledge of the full state for feedback. However, in practice knowledge of the full state is usually not available. Therefore, an asymptotically stabilizing MPC scheme for a class of nonlinear discrete-time systems is proposed, which only requires knowledge of the output of the system for feedback...

In the last decade, switched systems have gained much attention since a large class of practical systems can be modeled as switched systems (see e.g., (Dayawansa & Martin, 1999)) and there exist systems that cannot be asymptotically stabilized by a single continuous feedback control law (see e.g., (Brockett, 1983)). For stability analysis of switched systems, many interesting results have been ...