Design of Feedback Systems With Plant Input Rate Saturation via QFT Approach

2005 ◽  
Vol 128 (3) ◽  
pp. 701-705 ◽  
Author(s):  
Wei Wu ◽  
Suhada Jayasuriya
Keyword(s):  
Input Rate ◽  
Response Behavior ◽  
Feedback Systems ◽  
Describing Function ◽  
Robust Performance ◽  
Original Design ◽  
Design Constraints ◽  
Input Amplitude ◽  
Output Stability ◽  
Synthesis Approach

In this paper, a synthesis approach for input rate saturation compensation of feedback systems is presented. Uncertain, stable plants of type greater than or equal to 1 are considered. Based on Horowitz’s original design for input amplitude saturation (Horowitz, I., 1983) and extensions developed in (Wu, W., and Jayasuriya, S., 1999; Wu, W., and Jayasuriya, S., 2001; Wu, W., 2000) an independent loop around the rate saturating element is introduced for saturation compensation by means of the third DOF (degree of freedom) saturation compensator, H(s). First, the structure of the additional loop transmission is constructed to generate the desired response behavior on a systems recovery from saturation. Second, robust stability and robust performance under the addition of H(s) are investigated. The circle criterion, describing function, and nonovershooting conditions are utilized to generate design constraints. In the end, all design constraints involving saturation compensation are expressed as frequency domain bounds, and the synthesis of saturation compensator H(s) follows from loop shaping methods such as QFT. The proposed approach guarantees input/output stability under saturation for the plant class considered.

Design for Feedback Systems With Plant Input Amplitude and Rate Saturation

2005 ◽  
Vol 128 (3) ◽  
pp. 706-711 ◽  
Author(s):  
Wei Wu ◽  
Suhada Jayasuriya
Keyword(s):  
Frequency Domain ◽  
San Diego ◽  
Degrees Of Freedom ◽  
Synthesis Method ◽  
Feedback System ◽  
Input Output ◽  
Feedback Systems ◽  
Design Constraints ◽  
Input Amplitude ◽  
Output Stability

In this paper, a method of compensation for feedback systems subject to simultaneous plant input amplitude and rate saturation is presented. It applies to uncertain, stable plants of a type greater than or equal to 1. Founded on Horowitz’s original idea for amplitude saturation compensation (Horowitz, I., 1983, Int. J. Control, 38(1), pp. 169–197) and extensions developed in (Wu, W., and Jayasuriya, S., 1999, Proceedings of American Control Conference, San Diego, CA, pp. 3046–3050; Wu, W., and Jayasuriya, S., 2001, ASME J. Dyn. Syst., Meas., Control, 123(2), pp. 225–232; Wu, W., 2000, Ph.D. dissertation, Texas A&M University), a synthesis method that explicitly takes into account input amplitude and rate saturation is further developed. In the case of simultaneous amplitude and rate saturation, approaches developed separately for amplitude alone, and rate alone saturation (Wu, W., 2000, Ph.D. dissertation, Texas A&M University), respectively, are integrated into one method, and results in a 4DOF(degrees of freedom) feedback system with two extra compensators to deal with two saturation nonlinearities. Design constraints for saturation compensation are developed and expressed as frequency domain bounds. Synthesis of the two additional compensators follows from loop shaping methods, such as QFT. This approach guarantees input/output stability for the class of plants considered. Examples are given to illustrate the application of this approach.

Robust Non-Linear H∞/Adaptive Control of Robot Manipulator Motion

1994 ◽  
Vol 208 (4) ◽  
pp. 221-230 ◽  
Author(s):  
W Feng ◽  
I Postlethwaite
Keyword(s):  
Disturbance Rejection ◽  
Robot Manipulator ◽  
Control Design ◽  
System Modelling ◽  
Robust Performance ◽  
Original Design ◽  
Considerable Effort ◽  
Plant Model ◽  
Model Mismatch ◽  
Bounded Disturbances

In robotics, despite considerable effort to minimize system modelling errors, uncertainties are always present and sometimes significant. In this paper, modelling errors are first represented by a class of bounded disturbances in the input channels (torques) of the robot. A measure of the robot system's ability to reject these disturbances is formulated in an L2 gain sense and a control design is subsequently proposed to achieve optimal disturbance rejection. If more detailed information is available on the plant-model mismatch, then the control design can be modified to incorporate an adaptive scheme (with explicit parameter updating laws) in order to reduce the conservativeness of the original design and to improve robust performance of the overall system.

Some Analytically Determined Critical Jump-Resonance Curves

1970 ◽  
Vol 3 (2) ◽  
pp. T17-T19
Author(s):  
N. Ream
Keyword(s):  
Function Approximation ◽  
Dead Zone ◽  
Feedback Systems ◽  
Describing Function ◽  
Algebraic Expressions ◽  
Resonance Curves

Algebraic expressions are given for some critical jump-resonance curves in feedback systems containing one nonlinearity. The usual describing-function approximation is employed, and the following nonlinearities are considered: a) linear plus (2n + 1)th power, b) saturation with hysteresis, c) dead zone, d) backlash.

Stability of a Nonlinear Feedback System in the Presence of Gaussian Noise

1962 ◽  
Vol 84 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Rangasami Sridhar ◽  
Rufus Oldenburger
Keyword(s):  
Gaussian Noise ◽  
Natural Extension ◽  
Feedback System ◽  
Frequency Component ◽  
Analog Computer ◽  
Nonlinear Feedback ◽  
Feedback Systems ◽  
Describing Function ◽  
Power Spectral ◽  
Describing Function Method

A stability criterion for certain types of nonlinear feedback systems in the presence of Gaussian noise is established here. This criterion may be considered as a natural extension of the describing function method. It is assumed that the lowest frequency component in the power spectral density of the noise is at least ten times higher than the highest significant frequency of the system. The method developed here is applicable to feedback systems with just one instantaneous, nonmemory type nonlinearity in the loop. The results mentioned in this paper have been experimentally verified on an analog computer. The theory explained here may be used by the designer to predict the manner in which noise will affect the performance of a system.

Sign in / Sign up

Export Citation Format

Share Document