A Class of Transfer Functions With Non-Negative Impulse Response

1991 ◽  
Vol 113 (2) ◽  
pp. 313-315 ◽  
Author(s):  
S. Jayasuriya ◽  
M. A. Franchek

Presented in this note is a class of stable, minimum phase transfer functions whose impulse response is non-negative. A simple sufficiency criterion based on the relative locations of the poles and zeros characterizes the class. When the transfer function is in a factored form the sign of its impulse response may either be obtained by inspection or is inconclusive. A need for identifying such transfer functions was recently established by Jayasuriya (1989) who showed that a controller designed on the basis of maximizing a step input disturbance will reject a persistent disturbance bounded by the size of the maximized step if and only if the closed-loop system’s impulse response is of one sign.

1952 ◽  
Vol 40 (12) ◽  
pp. 1717-1723 ◽  
Author(s):  
P. Ordijng ◽  
F. Hopkins ◽  
H. Krauss ◽  
E. Sparrow

1995 ◽  
Vol 12 (6) ◽  
pp. 1191-1210 ◽  
Author(s):  
Duane G. Albrecht

AbstractThe responses of simple cells (recorded from within the striate visual cortex) were measured as a function of the contrast and the frequency of sine-wave grating patterns in order to explore the effect of contrast on the spatial and temporal phase transfer functions and on the spatiotemporal receptive field. In general, as the contrast increased, the phase of the response advanced by approximately 45 ms (approximately one-quarter of a cycle for frequencies near 5 Hz), although the exact value varied from cell to cell. The dynamics of this phase-advance were similar to the dynamics of the amplitude: the amplitude and the phase increased in an accelerating fashion at lower contrasts and then saturated at higher contrasts. Further, the gain for both the amplitude and the phase appeared to be governed by the magnitude of the contrast rather than the magnitude of the response. For the spatial phase transfer function, variations in contrast had little or no systematic effect; all of the phase responses clustered around a single straight line, with a common slope and intercept. This implies that the phase-advance was not due to a change in the spatial properties of the neuron; it also implies that the phase-advance was not systematically related to the magnitude of the response amplitude. On the other hand, for the temporal phase transfer function, the phase responses fell on five straight lines, related to the five steps in contrast. As the contrast increased, the phase responses advanced such that both the slope and the intercept were affected. This implies that the phase-advance was a result of contrast-induced changes in both the response latency and the shape/symmetry of the temporal receptive field.


2013 ◽  
Vol 284-287 ◽  
pp. 2199-2204
Author(s):  
Liang Yih Liu ◽  
Hsiung Cheng Lin

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.


Author(s):  
Meng-Sang Chew ◽  
Theeraphong Wongratanaphisan

Abstract This paper presents the analysis of the kinematics, dynamics and controls of tendon-driven mechanism under the framework of signal flow graphs. For decades, the signal flow graphs have been applied in many areas, particularly in controls, for determining the closed-loop transfer function of a control system. The tendon-driven mechanism considered here consists of several subsystems including actuator-controller dynamics, mechanism kinematics and mechanism dynamics. Each subsystem will be derived and represented by signal flow graphs. The representation of the whole system can be carried out by connecting the graphs of subsystems at the corresponding nodes. Transfer functions can then be obtained by using Mason’s rules. A 3-DOF robot finger utilizing tendon-driven mechanism is used as an illustrative example.


Author(s):  
Tarunraj Singh

This paper presents the development of an input-shaper/time-delay filter, which exploits knowledge of the zeros of a minimum-phase transfer function to reduce the output-transition time for a rest-to-rest maneuver problem, compared to the traditional zero vibration (ZV) input shaper. The maneuver time of the robust input shaper presented in this work will correspondingly have a smaller maneuver time compared to the zero vibration derivative (ZVD) input-shaper. The shaped profile is changing with time even after the completion of the maneuver similar to postactuation controllers. All the traditional technique for addressing multiple modes and desensitizing the filter over a specified domain of uncertainties are applicable to the technique presented in this paper.


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