Papers by Keyword: Non-Minimum Phase

Abstract: The pitch channel output tracking of a kind of ummanned aerial vehicle over-load control system was designed based on second order sliding mode control theory. Output-redefinition approach was adopted to resolve the non-minimum phase problem between rudder angle and overload output of ummanned aerial vehicle system, second order sliding mode control was used to eliminate chatter, and guaranteed the tracing of original system output. The observer was designed to deal with the not complete state measurable system. The stability and robustness were verified by the simulations results.

Abstract: This paper presents the effect of an integral feedback controller for minimizing the pointing error at the tip of a very flexible and slender cantilever beam to follow a command signal. A piezoeletric PZT actuator patch isbonded on near the clamped end of the cantilever beam. Also it is considered that a position sensor is located near the tip of the beam but it is not attached on the beam. The beam is designed to be lightly damped and its step response withoutcontrol is quite long. But because of the non-collocation of the sensor and actuator, the plant response is non-minimum phase. After an intensive computer simulation, it is noted that the integral controller can reduce the settling time with proper stability and control gains. Also an analysis and comparison of the integral controller with a proportional-integral controller for the pointing error minimization of the very flexible and slender beam is described in detail.

Abstract: There exist an infinite number of right-half plane zeros in the transfer function relating the joint torque input to the tip contact force output for a constrained single-link flexible arm. Since the non-minimum phase nature is the cause of instability or stability but caused the smaller control bandwidth. In order to overcome the inherent limitations caused by the non-minimum phase nature, a new input induced by the measurement of joint angular acceleration and a output generated using the measurements of contact force and root shear force are defined. A necessary and sufficient condition is derived such that all poles and zeros of the new transfer function lie on the imaginary axis. The passive integral control is designed to accomplish the regulation of the contact force. The excellent performance of the passive integral controller is verified through numerical simulations.

Abstract: In this paper, active control of periodic transient vibration based on repetitive control (RC) algorithm is studied. According to the stability condition of an active vibration control (AVC) system, a novel non-causal stable inversion approach combined with an optimal criterion is used to design the RC controller for an AVC system with a non-minimum phase secondary path. Computer simulations have been carried out to validate the effectiveness of the proposed algorithm. The plant model used in the computer simulations is obtained from a practical AVC system in our laboratory. Simulation results show that the proposed scheme can significantly reduce periodic transient vibration and the convergence rate is acceptable for a non-minimum phase plant.

Abstract: This paper presents experimental results of source identification for a non-minimum phase system. Generally, a causal linear system may be described by matrix form. The inverse problem is considered as a matrix inversion. Direct inverse method cannot be applied for a non-minimum phase system, because the system has ill-conditioning. Therefore, in this study the SVD inverse technique is introduced to execute an effective inversion. In a non-minimum phase system, its system matrix may be singular or near-singular and has very small singular values. These very small singular values have information about a phase of the system and ill-conditioning. Using this property we could solve the ill-conditioned problem of the system and then verify it for the practical system (cantilever beam). The experimental results show that the SVD inverse technique works well for a non-minimum phase system. This inverse technique can be applied to the estimation of the magnitude of impact force, which becomes often a cause of damage to a mechanical system.