Fault diagnosis for processes with feedback control loops by shifted output sampling approach

2018 ◽  
Vol 355 (7) ◽  
pp. 3249-3273
Author(s):  
Kai Wang ◽  
Junghui Chen ◽  
Zhihuan Song
Keyword(s):  
Fault Diagnosis ◽  
Feedback Control ◽  
Control Loops ◽  
Sampling Approach

Dynamics of Nonlinear Feedback Control

2007 ◽  
Vol 19 (5) ◽  
pp. 1179-1214 ◽  
Author(s):  
H. P. Snippe ◽  
J. H. van Hateren
Keyword(s):  
Feedback Control ◽  
Feedback Loop ◽  
Mathematical Form ◽  
Nonlinear Feedback Control ◽  
Nonlinear Feedback ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Control Loops ◽  
Low Pass ◽  
Multiplicative Control

Feedback control in neural systems is ubiquitous. Here we study the mathematics of nonlinear feedback control. We compare models in which the input is multiplied by a dynamic gain (multiplicative control) with models in which the input is divided by a dynamic attenuation (divisive control). The gain signal (resp. the attenuation signal) is obtained through a concatenation of an instantaneous nonlinearity and a linear low-pass filter operating on the output of the feedback loop. For input steps, the dynamics of gain and attenuation can be very different, depending on the mathematical form of the nonlinearity and the ordering of the nonlinearity and the filtering in the feedback loop. Further, the dynamics of feedback control can be strongly asymmetrical for increment versus decrement steps of the input. Nevertheless, for each of the models studied, the nonlinearity in the feedback loop can be chosen such that immediately after an input step, the dynamics of feedback control is symmetric with respect to increments versus decrements. Finally, we study the dynamics of the output of the control loops and find conditions under which overshoots and undershoots of the output relative to the steady-state output occur when the models are stimulated with low-pass filtered steps. For small steps at the input, overshoots and undershoots of the output do not occur when the filtering in the control path is faster than the low-pass filtering at the input. For large steps at the input, however, results depend on the model, and for some of the models, multiple overshoots and undershoots can occur even with a fast control path.

Feedback control of the neuromusculoskeletal system in a forward dynamics simulation of stair locomotion

2009 ◽  
Vol 223 (6) ◽  
pp. 663-675 ◽  
Author(s):  
A Selk Ghafari ◽  
A Meghdari ◽  
G Vossoughi
Keyword(s):  
Feedback Control ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Human Movement ◽  
Stair Climbing ◽  
Dynamics Simulation ◽  
Forward Dynamics ◽  
Control Loops ◽  
The Stability

The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional—integral—derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of pressure during locomotion. The parameters of the proposed controller were determined by employing the iterative feedback tuning approach to minimize tracking errors during forward dynamics simulation. Simultaneously, an inverse-dynamics-based optimization was employed to compute a set of desired musculotendon forces in the closed-loop simulation to resolve muscle redundancy. Quantitative comparisons of the simulation results with the experimental measurements and the reference muscles' activities illustrate the accuracy and efficiency of the proposed method during the stable ascending simulation.

Perfectly Matched Feedback Control and Its Integrated Design for Multiaxis Motion Systems

2004 ◽  
Vol 126 (3) ◽  
pp. 547-557 ◽  
Author(s):  
Syh-Shiuh Yeh ◽  
Pau-Lo Hsu
Keyword(s):  
Feedback Control ◽  
High Speed ◽  
Feedforward Control ◽  
Phase Error ◽  
Integrated Design ◽  
Cnc Machining ◽  
Dynamic Responses ◽  
Tracking Accuracy ◽  
Control Loops ◽  
Contouring Accuracy

For motion systems with multiple axes, the approach of matched direct current gains has been generally adopted to improve contouring accuracy under low-speed operations. To achieve high-speed and high-precision motion in modern manufacturing, a perfectly matched feedback control (PMFBC) design for multiaxis motion systems is proposed in this paper. By applying stable pole-zero cancellation and including complementary zeros for uncancelled zeros for all axes, matched dynamic responses across the whole frequency range for all axes are achieved. Thus, contouring accuracy for multiaxis systems is guaranteed for the basic feedback loops. In real applications, the modeling error is unavoidable and the degradation and limitations of the model-based PMFBC exist. Therefore, a newly designed digital disturbance observer is proposed to be included in the proposed PMFBC structure for each axis to compensate for undesirable nonlinearity and disturbances to maintain the matched dynamics among all axes for the PMFBC design. Furthermore, the feedforward control loops zero phase error tracking controller are employed to reduce tracking errors. Experimental results on a three-axis CNC machining center indicate that both contouring accuracy and tracking accuracy are achieved by applying the present PMFBC design.

scholarly journals TEACHING FEEDBACK CONTROL THEORY USING AN INTEGRATING DESIGN PROJECT

2015 ◽  
Author(s):  
Michel F. Couturier
Keyword(s):  
Feedback Control ◽  
Control Theory ◽  
Chemical Engineering ◽  
Final Report ◽  
Dynamic Simulations ◽  
Control Loops ◽  
Design Project ◽  
Dynamics And Control ◽  
The One ◽  
Feedback Control Theory

Teaching feedback control theory is challenging because it is important to cover theoretical material intended for fundamental understanding as well as material directly related to industrial practice. One approach to reach this dual objective and prevent control theory from becoming abstract to students is to assign a design project that requires integration of all main concepts taught in class. This approach has been successfully used in eight offerings of the course ChE 3601 Process Dynamics and Control in the Chemical Engineering program at the University of New Brunswick. The one-semester course is an introduction to the dynamic behavior of chemical processes and feedback control loops. The project is assigned at the beginning of the course and involves the design of a feedback control system for a realistic chemical process. The design project is divided into five milestones with deliverables due every two weeks. The final report due at the end of the course must include a description of the proposed system using a P&I diagram, specifications for all control equipment, a dynamic model for all components of the feedback loop, settings for the tuning parameters of the PID controller, and dynamic simulations using Polymath to validate the proposed solution. The course is organized around the project in a manner similar to that used in problem-based learning. The active learning approach used in ChE 3601 provides a deeper understanding of control theory and its application.

scholarly journals A Feedback Control Loop Optimisation Methodology for Floating Offshore Wind Turbines

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3490 ◽  
Author(s):  
Joannes Olondriz ◽  
Josu Jugo ◽  
Iker Elorza ◽  
Santiago Alonso-Quesada ◽  
Aron Pujana-Arrese
Keyword(s):  
Feedback Control ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Control Loop ◽  
Control Loops ◽  
Offshore Wind Turbines ◽  
Wind Turbine System ◽  
Floating Offshore Wind Turbines ◽  
The Cost

Wind turbines usually present several feedback control loops to improve or counteract some specific performance or behaviour of the system. It is common to find these multiple feedback control loops in Floating Offshore Wind Turbines where the system perferformance is highly influenced by the platform dynamics. This is the case of the Aerodynamic Platform Stabiliser and Wave Rejection feedback control loops which are complementaries to the conventional generator speed PI control loop when it is working in an above rated wind speed region. The multiple feedback control loops sometimes can be tedious to manually improve the initial tuning. Therefore, this article presents a novel optimisation methodology based on the Monte Carlo method to automatically improve the manually tuned multiple feedback control loops. Damage Equivalent Loads are quantified for minimising the cost function and automatically update the control parameters. The preliminary results presented here show the potential of this novel optimisation methodology to improve the mechanical fatigue loads of the desired components whereas maintaining the overall performance of the wind turbine system. This methodology provides a good balance between the computational complexity and result effectiveness. The study is carried out with the fully coupled non-linear NREL 5-MW wind turbine model mounted on the ITI Energy’s barge and the FASTv8 code.

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