A Frequency-Modulation Command-Shaping Strategy for Multi-Mode Systems

2013 ◽  
Author(s):  
Ziyad N. Masoud ◽  
Khaled A. Alhazza
Keyword(s):  
Frequency Modulation ◽  
Closed Loop ◽  
Single Mode ◽  
Mode Frequency ◽  
Loop System ◽  
Loop Model ◽  
Closed Loop System ◽  
Command Shaping ◽  
Scaled Models ◽  
Multi Mode

Single-mode shaped commands can be implemented for oscillations control of multi-mode systems provided that all frequencies of the system are odd-multiples of the shaped command frequency. This criterion is utilized in this work to develop a command shaping strategy for multi-mode systems. A frequency-modulation command shaper is derived based on the use of a single-mode command-shaping technique. The proposed strategy is based on deriving a closed-loop model of a multi-mode system with its modal frequencies modulated so that higher mode frequencies are odd-multiples of the first mode frequency. A single-mode double-step primary command-shaper with a design frequency equal to the first mode frequency of the closed-loop system is then used. The input command to the plant of the closed-loop system is used as shaped commands for the multi-mode system. Numerical simulations are used to demonstrate the performance of the proposed strategy along with experiments on scaled models of a triple, quadruple, and quintuple-pendulums.

Pseudo-random binary sequence closed-loop system identification error with integration control

2009 ◽  
Vol 223 (6) ◽  
pp. 877-884 ◽  
Author(s):  
Z Ren ◽  
G G Zhu
Keyword(s):  
System Identification ◽  
Closed Loop ◽  
Binary Sequence ◽  
Open Loop ◽  
Loop System ◽  
Loop Model ◽  
Closed Loop System ◽  
Identification Error ◽  
Closed Loop Identification ◽  
Integral Controller

This paper studies the closed-loop system identification (ID) error when a dynamic integral controller is used. Pseudo-random binary sequence (PRBS) q-Markov covariance equivalent realization (Cover) is used to identify the closed-loop model, and the open-loop model is obtained based upon the identified closed-loop model. Accurate open-loop models were obtained using PRBS q-Markov Cover system ID directly. For closed-loop system ID, accurate open-loop identified models were obtained with a proportional controller, but when a dynamic controller was used, low-frequency system ID error was found. This study suggests that extra caution is required when a dynamic integral controller is used for closed-loop system identification. The closed-loop identification framework also has significant effects on closed-loop identification error. Both first- and second-order examples are provided in this paper.

Closed-Loop System Identification Based on Data Correlation

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Hassene Jammoussi ◽  
Matthew Franchek ◽  
Karolos Grigoriadis ◽  
Martin Books
Keyword(s):  
System Identification ◽  
Instrumental Variables ◽  
Closed Loop ◽  
Linear Time ◽  
Open Loop ◽  
Loop System ◽  
Loop Model ◽  
Closed Loop System ◽  
Engine Operation ◽  
Single Input Single Output

A closed-loop system identification method is developed to estimate the parameters of a single input single output (SISO) linear time invariant system (LTI) operating within a feedback loop. The method uses the reference command in addition to the input–output data and establishes a correlation framework to structure the system. The correlation-based method is capable of delivering consistent estimates provided that the specific conditions on the signals are met. The method parallels the instrumental variables four step algorithm (IV4) and is comprised of three steps. First a model is estimated using cross correlation calculations between the reference input signal and the control and measured output signals. In the second step, a prefilter is identified to reduce estimation bias. In the final step, the prefilter, the instrumental variables and the measured signals are employed to estimate the final model. A consistency proof is provided for the proposed estimation process. The method is demonstrated on two examples. The first uses data collected from a diesel engine operation, and an open-loop model relating fueling to engine speed is sought. The identification process is complicated by the presence of nonmeasurable external torque disturbances and stochastic sensor noise. The second example uses data obtained from a time domain simulation of a closed-loop system where high levels of nonmeasured noise and disturbances were considered and a comparison with existing methods is made.

Command-Shaping Control System for Double-Pendulum Gantry Cranes

2011 ◽  
Author(s):  
Ziyad N. Masoud ◽  
Khaled A. Alhazza
Keyword(s):  
Closed Loop ◽  
Single Mode ◽  
Feedback System ◽  
Mode Frequency ◽  
Gantry Crane ◽  
Necessary Condition ◽  
Double Pendulum ◽  
Double Step ◽  
Scaled Model ◽  
Command Shaping

Traditionally, multi-mode command-shaping controllers are tuned to the system frequencies. This work suggests an opposite approach. A frequency-modulation (FM) strategy is developed to tune the system frequencies to match the frequencies eliminated by a single-mode command-shaper. The shaper developed in this work is based on a double-step command-shaping strategy. Using the FM Shaper, a simulated feedback system is used to modulate the closed-loop frequencies of a simulated double-pendulum model to the point where the closed-loop second mode frequency becomes an odd multiple of the closed-loop first mode frequency, which is the necessary condition for a satisfactory performance of a single-mode command-shaper. The double-step command-shaper is based on the closed-loop first mode frequency. The input commands to the plant of the simulated closed-loop system are then used to drive the actual double-pendulum. Performance is validated experimentally on a scaled model of a double-pendulum gantry crane.

Discrete-Time Closed-Loop Model Identification of Fixed-Structure Unstable Multivariable Systems

2007 ◽  
Author(s):  
Huzefa Shakir ◽  
Won-Jong Kim
Keyword(s):  
System Identification ◽  
Discrete Time ◽  
Closed Loop ◽  
Model Identification ◽  
Order Reduction ◽  
Loop System ◽  
Loop Model ◽  
Frequency Range ◽  
Closed Loop System ◽  
Closed Loop Identification

This paper presents improved empirical representations of a general class of open-loop unstable systems using closed-loop system identification. A multi-axis magnetic-levitation (maglev) nanopositioning system with an extended translational travel range is used as a test bed to verify the closed-loop system-identification method proposed in this paper. A closed-loop identification technique employing the Box-Jenkins (BJ) method and a known controller structure is developed for model identification and validation. Direct and coupling transfer functions (TFs) are then derived from the experimental input-output time sequences and the knowledge of controller dynamics. A persistently excited signal with a frequency range of [0, 2500] Hz is used as a reference input. An order-reduction algorithm is applied to obtain TFs with predefined orders, which give a close match in the frequency range of interest without missing any significant plant dynamics. The entire analysis is performed in the discrete-time domain in order to avoid any errors due to continuous-to-discrete-time conversion and vice versa. Continuous-time TFs are used only for order-reduction and performance analysis of the identified plant TFs. Experimental results in the time as well as frequency domains verified the accuracy of the plant TFs and demonstrated the effectiveness of the closed-loop identification and order-reduction methods.

Frequency-Modulation Input Shaping Control of Double-Pendulum Overhead Cranes

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Ziyad N. Masoud ◽  
Khaled A. Alhazza
Keyword(s):  
Frequency Modulation ◽  
Closed Loop ◽  
Single Mode ◽  
Mode Frequency ◽  
Input Shaping ◽  
Double Pendulum ◽  
Overhead Crane ◽  
Primary Input ◽  
Shaping Technique ◽  
Input Shaper

Traditionally, multimode input shaping controllers are tuned to systems' frequencies. This work suggests an alternative approach. A frequency-modulation (FM) input shaping technique is developed to tune the resonant frequencies of a system to a set of frequencies that can be eliminated by a single-mode primary input shaper. Most of the current input shaping techniques can be used as primary input shapers for the FM input shaping technique. Virtual feedback is used to modulate the closed-loop frequencies of a simulated double-pendulum model of an overhead crane to the point where the closed-loop second mode frequency becomes an odd-multiple of the closed-loop first mode frequency, which is the necessary condition for a satisfactory performance of most single-mode input shapers. The primary input shaper is based on the first mode frequency of the closed-loop system model. The input commands to the plant of the virtual feedback system are then used to drive the physical double-pendulum. Simulations results, using primary zero-vibration (ZV) and zero-vibration-derivative (ZVD) input shapers, are presented. The performance is validated experimentally on a scaled model of a double-pendulum overhead crane.

Algorithm for Closed Loop System Identification Based on Data Correlation

2008 ◽  
Author(s):  
H. Jammoussi ◽  
M. A. Franchek ◽  
K. Grigoriadis ◽  
M. Books
Keyword(s):  
System Identification ◽  
Instrumental Variables ◽  
Closed Loop ◽  
Open Loop ◽  
Loop System ◽  
Loop Model ◽  
Closed Loop System ◽  
Final Model ◽  
Cross Covariance ◽  
Step Algorithm

A closed loop system identification method is developed in which estimation bias from sensor noise and external disturbances is minimized. The method, based on the instrumental variables four step algorithm (IV4), uses three steps. The first step estimates a model using cross covariance calculations between the reference input signal and the control and measured output signals. The second step employs the prefilter identification process from the IV4 process. The third and final step uses the prefilter, the instrumental variables and the reference, control and output signals to estimate the final model. The method is demonstrated on a diesel engine where an open loop model relating fueling to engine speed is sought. The identification example is complicated by the presence of nonmeasurable external torque disturbances due to vehicle accessories.

Three-Dimensional Simulations of Blood Flow With Systemic Arterial Baroreflex

2009 ◽  
Author(s):  
H. J. Kim ◽  
C. A. Taylor
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Closed Loop ◽  
Three Dimensional ◽  
Element Model ◽  
Loop System ◽  
Loop Model ◽  
Arterial Baroreflex ◽  
Closed Loop System ◽  
Venous Compliance

The systemic arterial baroreflex controls the systemic arterial pressure to maintain homeostasis. The carotid sinus and aortic arch are the major systemic arterial baroreceptors, and they respond to distention of the carotid and aortic walls causing compensatory mechanisms, which regulate heart rate, cardiac contractility, peripheral arterial resistance, venous compliance, and venous unstressed volume [1]. In this study, we connect a feedback control loop, which represents the systemic arterial baroreflex, to the closed loop system we developed in a previous study [2]. The three-dimensional finite element model of the aorta and the closed loop system enable us to obtain not only the physiologic flow rate and pressure fields of the finite element model but also the global characteristics of the cardiovascular system from the closed loop model. We study the autoregulatory mechanisms occurring due to the systemic arterial baroreflex by considering the interactions between the heart and the systemic and pulmonary circulations.

Safety and Performance of the Omnipod®Hybrid Closed-Loop System in Adolescents with Type 1 Diabetes over Five Days Under Free-Living Conditions

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 1376-P
Author(s):  
GREGORY P. FORLENZA ◽  
BRUCE BUCKINGHAM ◽  
JENNIFER SHERR ◽  
THOMAS A. PEYSER ◽  
JOON BOK LEE ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Closed Loop ◽  
Living Conditions ◽  
Loop System ◽  
Closed Loop System ◽  
Free Living ◽  
And Performance ◽  
Free Living Conditions
Sign in / Sign up

Export Citation Format

Share Document