Output Zeroing Research Articles

Common Noninteracting Control with Simultaneous Common Partial Zeroing with Application to a Tracked UGV

In several MIMO system applications, the deviations of some output performance variables from their nominal values are required to be controlled independently, while the other performance variables are required to remain at their nominal value. This problem, named noninteracting control with simultaneous partial output zeroing, is important in the case of the common design of multi-model systems. To this end, the problem of a common noninteracting control with simultaneous common partial output zeroing is formulated. The present paper aims to develop a solution to the problem of multi-model normal linear time-invariant systems via regular and static measurement output feedback. The present approach follows the method developed for the solution of the common I/O decoupling problem. The main results of the paper are the introduction and the formulation of the problem at hand, the establishment of the necessary and sufficient conditions for its solvability, and the derivation of the respective general solution of the controller matrices. For the resulting closed-loop system, the additional design requirement of approximate command following a simultaneous I/O stabilizability is studied using a composite norm 2 type cost function and a metaheuristic algorithm for the derivation of the free parameters of the controller. The present results are illustrated through a numerical example of a nonlinear process with two operating points. Moreover, all the above results are successfully applied to the two-model description of a robot-tracked UGV, using a common controller feeding back measurements of the motor currents and the orientation of the vehicle.

Antenna System for Trilateral Drone Precise Vertical Landing

This paper presents a radio frequency system that can be used to perform precise vertical landings of drones. The system is based on the three-way phase shift detection of a signal transmitted from the landing point. The antenna system is designed by taking into account parameters such as landing tracking area, analog to digital converter (ADC) resolution, phase detector output range, antenna polarization and the effect of antenna axial ratio. The fabricated prototype consists of a landing point antenna that transmits a signal at 2.46 GHz, as well as a drone tri-antenna system that includes a phase shift detection circuitry, ADC and a simple control program that provides the correction instructions for landing. The prototype provides an averaged output data rate (ODR) suitable for landing maneuvers (>300 Hz). A simple system calibration procedure (detector output zeroing) is performed by aligning the antenna system. The measurements performed at different altitudes demonstrate both the correct operation of the proposed solution and its viability as an instrument for precision vertical landings.

A Systematic Design of Backstepping-Based State Feedback Controllers for ODE-PDE-ODE Systems

The backstepping design of stabilizing state feedback controllers is addressed for bidirectionally coupled ODE-PDE-ODE systems, that naturally arise for infinite-dimensional systems where actuator or sensor dynamics are taken into account. A common framework for both linear parabolic and hyperbolic partial differential equations with spatially varying coefficients is presented, that solely relies on the strict feedback form of these systems. Without imposing any limitation on the dimension of the ODEs and PDEs involved, a multi-step design algorithm is suggested, that makes use of classical concepts (such as integrator backstepping and output zeroing) known for the control of ODE systems. By that, backstepping is brought back to its ODE origins and a systematic design of backstepping controllers for ODE-PDE-ODE systems is offered, with a unified treatise for parabolic and hyperbolic PDEs.

On the zero dynamics of linear input–output models

Zeros are of extreme importance in linear systems theory, especially unstable zeros, which degrade achievable performance. Furthermore, the presence of a zero in a state-space model implies the existence of an initial condition and a nonzero input signal such that the output is identically zero; this property is called output zeroing. The purpose of this paper is to elucidate the properties of the zero dynamics within the context of input–output models, which, like state-space models, are time-domain models, but, unlike state-space models, have no internal state. In particular, the focus is on the zero dynamics of left polynomial fraction description (LPFD) input–output models whose denominator polynomial is not necessarily monic.

Contact force control of an active pantograph for high speed trains

In this paper, a mathematical model of the pantograph with flexibility is developed based on experiments, and then an optimal controller together with a sliding observer is proposed to regulate the contact force in the presence of variation with respect to the equivalent stiffness of the catenary system. Furthermore, some physical interpretations of the closed-loop dynamics and pole-zero cancelations are given by analysis from a viewpoint of the output zeroing.

Input–output feedback linearization for nonminimum phase nonlinear systems through periodic use of synthetic outputs

Input–output feedback linearization provides a convenient means of extending linear control strategies such as output zeroing or pole placement to the case of nonlinear affine in the input systems, but such extensions cannot be applied in the presence of nonminimum phase characteristics. This paper overcomes this difficulty through the periodic use of a finite number of synthetic outputs which are so constructed as to define embedded dynamics with stable zero dynamics. The efficacy of the method is demonstrated by means of a numerical example.

Output zeroing of MIMO plants in the presence of actuator and sensor uncertain hysteresis nonlinearities

This note tackles the output zeroing problem of a square multiple-input-multiple-output plant containing uncertain nonsmooth hysteresis-like nonlinearities in actuator and sensor devices simultaneously. To this purpose, a robust sliding mode controller, based on the output of a reduced order observer, has been designed using it, such control law ensuring both the asymptotical zeroing of the sensing nonlinearities output and the boundedness of the unavailable states. Theoretical results have been validated by simulation.

Dynamic Output Feedback Variable Structure Control for the Output Stabilization of MIMO Uncertain Plants with Actuator and Sensor Hysteresis Nonlinearities

This paper addresses the measured output zeroing problem of a square plant containing non-smooth nonlinearities in actuator and sensor devices. An “extended” hysteresis model has been proposed, and a robust sliding mode controller, based on the output of a reduced order observer, has been synthesized; such control law ensures both the measured output zeroing and the boundedness of the unavailable states. Theoretical results have been validated by simulation.

Output zeroing with internal stability by learning

We formulate a novel learning algorithm for output zeroing of linear finite-dimensional, control systems. As in classical control systems theory, we start from the knowledge of a nominal plant to develop a feedback algorithm that achieves the control objective by means of successive trials on the plant. Algorithm convergence in the face of linear plant perturbations is proved, and performance in the face of small nonlinear perturbations is discussed. The proposed algorithm does not require output differentiation, and is based upon the learning of the initial conditions that allow the output to remain identically zero, while the state of the system, dynamically extended, freely evolves complying with an internal stability constraint. Implementation of this algorithm requires state initialization at an arbitrary point of the state space. Therefore, for those systems for which direct state initialization is not feasible, we develop a learning procedure that automatically accomplishes this task. By means of a control input generated by the algorithm, the state of the system is steered, during an initial phase, from a point where it is easily initialized to the point from which the output zeroing task starts. An illustrative example is included.

Disturbance Cancellation Control for Vibration of Multi-Degree-of-Freedom Systems : Case of Using Active Vibration Absorber and Active Dynamic Vibration Absorber

This paper describes a control system design method concerning feedback and feedforward control to cancel disturbance forces, for two kinds of active vibration control devices. One is the active vibration absorber (AVA) utilizing a fixed point for a civil structure such as a bridge, and the other is the active dynamic vibration absorber (ADVA) utilizing an auxiliary mass for a buildinglike structure. We have built two test rigs to simulate large structures with an AVA or an ADVA. In order to carry out fast computation, including the estimation of disturbances, we have used a digital signal processor (DSP). In conclusion, we found that the disturbance forces are perfectly cancelled and the output zeroing is actually realized when the disturbance frequency is exactly equivalent to the design frequency of the observer. We have confirmed that the proposed disturbance cancellation control is very useful for active vibration control.

Disturbance Cancellation Control for Vibration of Multi-Degree-of Freedom Systems. Case of Using Active Vibration Absorber and Active Dynamic Vibration Absorber.

This paper describes a control system design method concerning feedback and feedforward control to cancel disturbance forces, for two kinds of active vibration control devices. One is the active vibration absorber (AVA) utilizing a fixed point for a civil structure such as a bridge, and the other is the active dynamic vibration absorber (ADVA) utilizing an auxiliary mass for a buildinglike structure. We have built two test rigs to simulate large structures with an AVA or an ADVA. In order to carry out fast computation, including the estimation of disturbances, we have used a digital signal processor (DSP). In conclusion, we found that the disturbance forces are perfectly cancelled and the output zeroing is actually realized when the disturbance frequency is exactly equivalent to the design frequency of the observer. We have confirmed that the proposed disturbance cancellation control is very useful for active vibration control.

Output function control in general state space systems containing the first derivative of the input vector

Abstract In this paper, linear control systems are considered whose state equation is of the form Edx/ dt = AX+ Bo u + B1 where A, B,o and and B1 constant matrices, while E is a square matrix that may be singular and time-varying. The problem to be solved is if the output of the system is a prescribed function of find inputs that generate the desired output. The results are readily applicable to ‘ output zeroing problems ’ for example to the calculation of the finite and infinite zeros and the corresponding Zero-directions of regular and singular time-invariant systems. The assumption that E may have time-varying elements makes the method developed in tho paper applicable to certain perturbation problems.

Dead-beat output zeroing by input and output feedback in multivariable delay-differential systems

A procedure is presented for the design of feedback controllers for zeroing the output, in finite time, of multivariable delay-differential systems. An algebraic approach is used, where distributions (generalized functions) and module theory are introduced. The computations needed to obtain the controllers can be carried out within a purely algebraic framework. The resulting feedback controllers can be realized by interconnections of integrators and delay elements.