Development of a semi-automated model identification and calibration tool for conceptual modelling of sewer systems

2013 ◽  
Vol 68 (1) ◽  
pp. 167-175 ◽  
Author(s):  
Vincent Wolfs ◽  
Mauricio Florencio Villazon ◽  
Patrick Willems
Keyword(s):  
Model Identification ◽  
Computation Time ◽  
Conceptual Modelling ◽  
Storm Events ◽  
Real Time Control ◽  
Design Storm ◽  
Time Control ◽  
Long Time ◽  
Modelling Methodology ◽  
Time Required

Applications such as real-time control, uncertainty analysis and optimization require an extensive number of model iterations. Full hydrodynamic sewer models are not sufficient for these applications due to the excessive computation time. Simplifications are consequently required. A lumped conceptual modelling approach results in a much faster calculation. The process of identifying and calibrating the conceptual model structure could, however, be time-consuming. Moreover, many conceptual models lack accuracy, or do not account for backwater effects. To overcome these problems, a modelling methodology was developed which is suited for semi-automatic calibration. The methodology is tested for the sewer system of the city of Geel in the Grote Nete river basin in Belgium, using both synthetic design storm events and long time series of rainfall input. A MATLAB/Simulink® tool was developed to guide the modeller through the step-wise model construction, reducing significantly the time required for the conceptual modelling process.

Modifications of rainfall runoff and decision finding models for on-line simulation in real time control

1999 ◽  
Vol 39 (9) ◽  
pp. 201-207
Author(s):  
Andreas Cassar ◽  
Hans-Reinhard Verworn
Keyword(s):  
Real Time ◽  
Urban Drainage ◽  
Rain Event ◽  
Rainfall Runoff ◽  
Real Time Control ◽  
Design Storm ◽  
Time Control ◽  
Timing Data ◽  
On Line ◽  
Rainfall Runoff Model

Most of the existing rainfall runoff models for urban drainage systems have been designed for off-line calculations. With a design storm or a historical rain event and the model system the rainfall runoff processes are simulated, the faster the better. Since very recently, hydrodynamic models have been considered to be much too slow for real time applications. However, with the computing power of today - and even more so of tomorrow - very complex and detailed models may be run on-line and in real time. While the algorithms basically remain the same as for off-line simulations, problems concerning timing, data management and inter process communication have to be identified and solved. This paper describes the upgrading of the existing hydrodynamic rainfall runoff model HYSTEM/EXTRAN and the decision finding model INTL for real time performance, their implementation on a network of UNIX stations and the experiences from running them within an urban drainage real time control project. The main focus is not on what the models do but how they are put into action and made to run smoothly embedded in all the processes necessary in operational real time control.

Determination of the Minimum Distance Between Moving Objects Including Velocity Information

1993 ◽  
Author(s):  
Meyer Nahon
Keyword(s):  
Minimum Distance ◽  
Moving Objects ◽  
Rapid Determination ◽  
Computation Time ◽  
Optimization Techniques ◽  
Real Time Control ◽  
Time Step ◽  
Time Control ◽  
Velocity Information

Abstract The rapid determination of the minimum distance between objects is of importance in collision avoidance for a robot maneuvering among obstacles. Currently, the fastest algorithms for the solution of this problem are based on the use of optimization techniques to minimize a distance function. Furthermore, to date this problem has been approached purely through the position kinematics of the two objects. However, although the minimum distance between two objects can be found quickly on state-of-the-art hardware, the modelling of realistic scenes entails the determination of the minimum distances between large numbers of pairs of objects, and the computation time to calculate the overall minimum distance between any two objects is significant, and introduces a delay which has serious repercussions on the real-time control of the robot. This paper presents a technique to modify the original optimization problem in order to include velocity information. In effect, the minimum distance calculation is performed at a future time step by projecting the effect of present velocity. This method has proven to give good results on a 6-dof robot maneuvering among obstacles, and has allowed a complete compensation of the lags incurred due to computational delays.

A Quasi-Dimensional Fuel Distribution Model for a Radially Stratified Engine

2021 ◽  
Author(s):  
Dennis Robertson ◽  
Patrick O'Donnell ◽  
Benjamin Lawler ◽  
Robert Prucka
Keyword(s):  
Reference Model ◽  
Computation Time ◽  
Distribution Model ◽  
Strategy Development ◽  
Real Time Control ◽  
Spray Penetration ◽  
Fuel Distribution ◽  
Time Control ◽  
Fuel Stratification ◽  
Execution Speed

Abstract Several combustion strategies leverage radial fuel stratification to adapt combustion performance between the center of the chamber and the outer regions independently. Spark-assisted compression ignition (SACI) relies on careful tuning of this radial stratification to maximize the combined performance of flame propagation and autoignition. Established techniques for determining in-cylinder fuel stratification are computationally intensive, limiting their feasibility for control strategy development and real-time control. A simplified model for radial fuel stratification is developed for control-oriented objectives. The model consists of three submodels: spray penetration, fuel distribution along the spray axis, and post-injection mixing. The spray penetration model is adapted from fuel spray models presented in the literature. The fuel distribution and mixing submodels are validated against injection spray results from an LES 3-D computational fluid dynamics (CFD) reference model for three test points as a function of crank angle. The quasi-one-dimensional model matches the CFD results with a root mean square error (RMSE) for equivalence ratio of 0.08?0.11. This is a 50% reduction from the 0.16?0.20 RMSE for a model that assumes a uniform fuel distribution immediately after injection. The computation time is 230 ms on an Intel Xeon E5-1620 v3 to solve each case without significant optimization for code execution speed.

Identifying useful real-time control parameters in ozonation process

2000 ◽  
Vol 42 (3-4) ◽  
pp. 435-440 ◽  
Author(s):  
C.-P. Yu ◽  
Y.-H. Yu
Keyword(s):  
Real Time ◽  
Ozone Concentration ◽  
Control Parameters ◽  
Real Time Control ◽  
Reactor Outlet ◽  
Time Control ◽  
Long Time ◽  
Three Stages ◽  
The Mean ◽  
State Curve

Industrial wastewaters that contain phenolic compounds are resistant to biodegradation and need preoxidation to improve their biodegradabilities. Preoxidation of these wastewaters by using ozone as the chemical oxidant has been found previously to be quite effective in promoting their biodegradability. In combined ozonation and biological processes, if we want to stop ozonation at the optimum condition (i.e. the maximum biodegradability), a biodegradation test is required. Since biodegradation tests such as BOD/TOC and oxygen uptake would take a long time, we could not know the time to stop ozonation immediately. This study was undertaken to identify process parameters (pH, ORP, ozone concentration in water, ozone gas concentration at the reactor outlet) that could be useful for monitoring and real-time control purposes in ozonation processes. We want to correlate these parameters with biodegradability and intermediates formed in ozonation processes. Results showed that the rapid increase of dissolved ozone and the first plateau termination of off-gas ozone concentrations are good indicators for the depletion of p-nitrophenol, the maximum of biodegradability and the elimination of toxicity. From the mean oxidation state curve, ozonation of p-nitrophenol could be divided into three stages, and a similar pattern could also be observed in ORP profiles. From the results of this research, the application of ozone concentration and ORP profiles as real-time control parameters seems promising.

Control Design for Automated Vehicle Emergency Safe Stop System Based on Differential Dynamic Programming

2020 ◽  
Author(s):  
Lisheng Yang ◽  
Tomonari Furukawa ◽  
Lei Zuo ◽  
Zachary Doerzaph
Keyword(s):  
Dynamic Programming ◽  
Real Time ◽  
Control Algorithm ◽  
Computation Time ◽  
Grid Cell ◽  
System Control ◽  
Real Time Control ◽  
Differential Dynamic Programming ◽  
Time Control ◽  
Emergency Stop

Abstract This paper presents the control algorithm and system design for a newly proposed automated emergency stop system, which aims to navigate the vehicle out of its travel lane to a safe road-side location when an emergency (e.g. driver fails to take control during fallback of the Dynamic Driving Task) occurs. To address the unique requirements of such a system, control techniques based on differential dynamic programming are developed. Optimal control sequence computation is broken down into step-by-step quadratic optimization and solved iteratively. Control constraints are addressed efficiently by a tailored Projected-Newton algorithm. The iterative control algorithm is then integrated into a real-time control system which considers both computation delay and modeling errors. The system employs a novel grid-based storage structure for recording all acceptable control commands computed within the iteration and uses a high frequency estimator for self-localization. During operation, the real-time control thread will extract commands from the grid cell corresponding to current states. Simulation results show strong potential of the proposed system for addressing the engineering challenges of the automated emergency stop function. The robustness of the system in presence of computation time delay and modelling errors is also demonstrated.

Analysis of a Multibody Elastodynamic Model for Closed-Loop Kinematic Mechanisms

2019 ◽  
Author(s):  
Luca Carbonari ◽  
Stefano Brillarelli ◽  
Matteo-Claudio Palpacelli ◽  
Massimo Callegari
Keyword(s):  
Closed Loop ◽  
Control Algorithms ◽  
Real Time Control ◽  
Kinematic Chains ◽  
Time Control ◽  
Single Link ◽  
Parallel Kinematic ◽  
Kinematic Mechanisms ◽  
Time Required ◽  
The Relationship

Abstract This paper is focused on the analysis of an elastodynamic model, typically referred to single-link flexible manipulators, when it is extended to multibody systems with closed-loop kinematic chains subject to vibrations, caused by the slenderness of their mechanical structure together with severe dynamic working conditions. The work is aimed at analyzing the relationship between the degree of accuracy of the proposed elastodynamic model, compared with more complete but time consuming models developed with software, and the time required for its computation, with the final aim of guiding its implementation in real-time control algorithms. Notwithstanding the study is proposed for parallel kinematic machines, the results are also valid for serial kinematic chains.

scholarly journals Comparing methods to place adaptive local RTC actuators for spill volume reduction from multiple CSOs

2021 ◽  
Author(s):  
M. Eulogi ◽  
S. Ostojin ◽  
P. Skipworth ◽  
S. Kroll ◽  
J. D. Shucksmith ◽  
...  
Keyword(s):  
Time Series ◽  
Control Device ◽  
Volume Reduction ◽  
Rainfall Time Series ◽  
Storm Events ◽  
Real Time Control ◽  
Location Selection ◽  
Time Control ◽  
Computational Resources

Abstract The selection of flow control device (FCD) location is an essential step for designing real-time control (RTC) systems in sewer networks. In this paper, existing storage volume-based approaches for location selection are compared with hydraulic optimisation-based methods using genetic algorithm (GA). A new site pre-screening methodology is introduced, enabling the deployment of optimisation-based techniques in large systems using standard computational resources. Methods are evaluated for combined sewer overflow (CSO) volume reduction using the CENTAUR autonomous local RTC system in a case study catchment, considering overflows under both design and selected historic rainfall events as well as a continuous 3-year rainfall time series. The performance of the RTC system was sensitive to the placement methodology, with CSO volume reductions ranging between −6 and 100% for design and lower intensity storm events, and between 15 and 36% under continuous time series. The new methodology provides considerable improvement relative to storage-based design methods, with hydraulic optimisation proving essential in relatively flat systems. In the case study, deploying additional FCDs did not change the optimum locations of earlier FCDs, suggesting that FCDs can be added in stages. Thus, this new method may be useful for the design of adaptive solutions to mitigate consequences of climate change and/or urbanisation.

scholarly journals A geometric approach for follow-the-leader motion of serpentine manipulator

2019 ◽  
Vol 16 (5) ◽  
pp. 172988141987463 ◽  
Author(s):  
Haibo Xie ◽  
Cheng Wang ◽  
Shusen Li ◽  
Liang Hu ◽  
Huayong Yang
Keyword(s):  
Path Planning ◽  
Real Time ◽  
Obstacle Avoidance ◽  
Degrees Of Freedom ◽  
Mechanical Design ◽  
Computation Time ◽  
Geometric Approach ◽  
Real Time Control ◽  
Time Control ◽  
The Ideal

This article presents a geometric approach for path planning of serpentine manipulator for real-time control in confined spaces. Firstly, the mechanical design of a serpentine manipulator is introduced, and its kinematics is analyzed. As the serpentine manipulator usually has more than 10 degrees of freedom, the motion control and obstacle avoidance are difficult considering its inverse kinematics. Follow-the-leader is an ideal path planning method for serpentine manipulator, as the manipulator moves forward, all the sections follow the path that the tip of manipulator has passed, which simplifies the obstacle avoidance. The realization of follow-the-leader method is to find the new configurations of the manipulator that can fit the ideal path with small errors. In this article, a novel geometric approach for follow-the-leader motion is proposed to solve new configurations with high precision of location and less computation time. The method is validated through simulation and the deviation from the ideal path is analyzed, simulation results show that calculation time for per step is less than 0.5 ms for a serpentine manipulator with 10 sections. To verify the follow-the-leader method, a 13-degree-of-freedom serpentine manipulator system with 6 sections was built, and 12 magnetic rotary encoders were embedded into the universal joints to collect data of rotation angles of each section. Experimental results show that the manipulator can carry out follow-the-leader motion as expected in real time.

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