Nonlinear Control Input Research Articles

Design and implementation of force and position control with anti-windup conditioned transfer compensation

This paper investigates the design and implementation of a force and position servo control system where non-linearities are encountered due to constraint on the torque signal to the motor drive, and switching between position and force controllers. The so-called two-step design paradigm is employed, whereby the velocity, position and force controllers are designed first ignoring control input non-linearities, and then anti-windup and conditioned transfer compensators are added using the Hanus conditioning technique. Both linear position and force controllers are designed using the H∞ loop shaping design procedure, and the H∞ controllers are found such that the Hanus conditioning technique for anti-windup conditioned transfer compensation can be applied. The overall controller is derived and presented in the state space framework, and its performance is evaluated in real time on an experimental set-up using a commercial digital signal processor.

123 MRダンパーを用いたセミアクティブサスペンションのインテグラルスライディングモード制御(非線形制御理論応用I)(OS 非線形制御理論応用)

In the design of sliding mode controllers for semi-active suspensions it is difficult to guarantee the existence of the sliding mode completely, which provides robust properties to the systems, because of the passivity constraints. This paper presents a new strategy for the design methods to hold the sliding mode as long as possible, using the Integral Sliding Mode theory, which was proposed by V.Utkin and J.Shi. The straregy is roughly described as follows: when the value of the switiching funct ion is almost equal to zero, the nonlinear control input used to reject undesired disturbances is better when it is as small as possible. This straregy leads to a dead zone algorithm. Numerical simulations and experimental results show the validity of the effectiveness of the controller.

Output Feedback Sliding Mode Control for Bending and Torsional Vibration Control of 6-Stories Flexible Structure.

We discuss bending and torsional vibration control of the 6-stories flexible structure. In the case where they consider structural control like high rise building, it is required to design a controller to have good control performance and simple designing for cutting down on personnel. So, we apply sliding mode control that is nonlinear robust control theory. Adopting this theory, control system design becomes very easy, and it takes too short time to design. However this controller is done by state feedback in general way, and it is difScult to do. Because it's few cases that sensors are placed in all stories. For this, sliding mode controller should be designed with output feedback, so we designed two output feedback sliding mode controller by using minimum error excitation method. The first is constructed by only nonlinear control inputs, and the second is done linear and nonlinear input. And, we investigated their performance using such controllers with numerical simulations and experiments. Consequently, we explain design methods and control system design constraints, and characteristics for flexible structural control.

A unified framework for the study of anti-windup designs

We present a unified framework for the study of linear time-invariant (LTI) systems subject to control input nonlinearities. The framework is based on the following two-step design paradigm: ‘design the linear controller ignoring control input nonlinearities and then add anti-windup bumpless transfer (AWBT) compensation to minimize the adverse effects of any control input nonlinearities on closed loop performance’. The resulting AWBT compensation is applicable to multivariable controllers of arbitrary structure and order. All known LTI anti-windup and/or bumpless transfer compensation schemes are shown to be special cases of this framework. This unification of existing schemes for AWBT compensation under a general framework is the main result of the paper.

Lyapunov redesign for structural convergence improvement in adaptive control

The relative improvement of the convergence rate in adaptive error models is discussed. It is shown how to improve convergence, positive realness, and robustness by modifying the structure of the error model. The proposed approaches to designing adaptive control algorithms using the Lyapunov method not only improve the rate of convergence but also provide flexibility in choosing nonlinear control inputs. Boundedness of the nonlinear functions of the modified schemes is shown. >