Control Strategies for a Highly Loaded Biological Ammonia Elimination Process

1993 ◽  
Vol 28 (11-12) ◽  
pp. 531-538 ◽  
Author(s):  
B. Teichgräber
Keyword(s):  
Closed Loop ◽  
Control Strategies ◽  
Level Control ◽  
Sludge Dewatering ◽  
Loop Control ◽  
Reject Water ◽  
Line Measurement ◽  
Control Pattern ◽  
On Line ◽  
Treatment Facilities

A nitrification/denitrification process was applied to reject water treatment from sludge dewatering at Bottrop central sludge treatment facilities of the Emschergenossenschaft. On-line monitoring of influent and effluent turbidity, closed loop control of DO and pH, and on-line monitoring of nitrogen compounds were combined to a three level control pattern. Though on-line measurement of substrate and product showed substantial response time it could be used to operate nitrification/denitrification within process boundaries.

On-Line Thermal Balancing Technique for a Large Turbo-Generator

1992 ◽  
Vol 114 (1) ◽  
pp. 60-66 ◽  
Author(s):  
M. Zumbach ◽  
G. Schweitzer ◽  
K. Schoellhorn
Keyword(s):  
Closed Loop ◽  
Control Strategies ◽  
Operating Conditions ◽  
Loop Control ◽  
Turbo Generator ◽  
Closed Loop Control System ◽  
Input Signals ◽  
Loop Control System ◽  
On Line ◽  
A New Technique

In this paper a new technique is proposed to rebalance automatically a large turbo-generator during operation. The sensitivity of the rotor unbalances to thermal asymmetries in the rotor is exploited by mounting some heating elements and using them as actively controlled actuators. The shaft vibrations are measured and used as input signals of the feedback controller. Unbalances thus can be compensated during rotor operation. A theoretical model of the thermo-elastic rotor has been developed and an appropriate closed-loop control system has been designed. The simulation results are verified on a special test rig with digital control allowing for varioius control strategies and various operating conditions.

pH-controlled reject-water-treatment

1998 ◽  
Vol 37 (12) ◽  
pp. 165-172 ◽  
Author(s):  
B. Wett ◽  
R. Rostek ◽  
W. Rauch ◽  
K. Ingerle
Keyword(s):  
Ph Value ◽  
Batch Reactor ◽  
Treatment Plant ◽  
Nitrogen Loading ◽  
High Concentration ◽  
Loop Control ◽  
Reject Water ◽  
Line Measurement ◽  
Initial Ph ◽  
On Line

Dewatering of digested sludge causes significant internal nitrogen loading to a wastewater treatment plant. Due to the high concentration of nitrogen it is more effective to treat the reject-water not directly in the main purification process but to apply a separate biological treatment procedure. The intermittent operation of sludge-press facilities, the high initial pH-value of reject-water and the quick loss of alkalinity during nitrification makes a reliable control of the process necessary. A sequencing batch reactor (SBR) with an operational control based on on-line measurement of the pH-value is well suited to meet this requirement. Such a control system for discontinuous treatment of reject-water has been extensively tested and optimised in full-scale experiments since 1995. The closed loop control of the pH-value was developed to keep the bicarbonate concentration within an optimum range. At the WWTP Strass in western Austria stable nitrification rates of 50 to 60 mg NH4-N/l/h have been achieved (elimination of 200 kg nitrogen per day).

scholarly journals Modeling and Reconstruction of State Variables for Low-Level Control of Soft Pneumatic Actuators

2021 ◽  
Vol 8 ◽  
Author(s):  
Serhat Ibrahim ◽  
Jan Christoph Krause ◽  
Alexander Olbrich ◽  
Annika Raatz
Keyword(s):  
Inertial Measurement Unit ◽  
Closed Loop ◽  
Measurement Unit ◽  
Closed Loop Control ◽  
State Variables ◽  
Level Control ◽  
Pneumatic Actuators ◽  
Loop Control ◽  
Inertial Measurement ◽  
Low Level

To further advance closed-loop control for soft robotics, suitable sensor and modeling strategies have to be investigated. Although there are many flexible and soft sensors available, the integration into the actuator and the use in a control loop is still challenging. Therefore, a state-space model for closed-loop low-level control of a fiber-reinforced actuator using pressure and orientation measurement is investigated. To do so, the integration of an inertial measurement unit and geometric modeling of actuator is presented. The piecewise constant curvature approach is used to describe the actuator’s shape and deformation variables. For low-level control, the chamber’s lengths are reconstructed from bending angles with a geometrical model and the identified material characteristics. For parameter identification and model validation, data from a camera tracking system is analyzed. Then, a closed-loop control of pressure and chambers’ length of the actuator is investigated. It will be shown, that the reconstruction model is suitable for estimating the state variables of the actuator. In addition, the use of the inertial measurement unit will demonstrate a cost-effective and compact sensor for soft pneumatic actuators.

scholarly journals Local flow sensing on helical microrobots for semi-automatic motion adaptation

2019 ◽  
Vol 39 (4) ◽  
pp. 476-489 ◽  
Author(s):  
Antoine Barbot ◽  
Dominique Decanini ◽  
Gilgueng Hwang
Keyword(s):  
Closed Loop ◽  
Flow Speed ◽  
Closed Loop Control ◽  
Flow Profile ◽  
Microfluidic Chips ◽  
Level Control ◽  
Local Flow ◽  
Loop Control ◽  
Flow Sensing ◽  
Swimming Motion

Helical microrobots with dimensions below 100 µm could serve many applications for manipulation and sensing in small, closed environments such as blood vessels or inside microfluidic chips. However, environmental conditions such as surface stiction from the channel wall or local flow can quickly result in the loss of control of the microrobot, especially for untrained users. Therefore, to automatically adapt to changing conditions, we propose an algorithm that switches between a surface-based motion of the microrobot and a 3D swimming motion depending on the local flow value. Indeed swimming is better for avoiding obstacles and difficult surface stiction areas but it is more sensitive to the flow than surface motion such as rolling or spintop motion. First, we prove the flow sensing ability of helical microrobots based on the difference between the tracked and theoretical speed. For this, a 50 µm long and 5 µm diameter helical microrobot measures the flow profile shape in two different microchannels. These measurements are then compared with simulation results. Then, we demonstrate both swimming and surface-based motion using closed-loop control. Finally, we test our algorithm by following a 2D path using closed-loop control, and adapting the type of motion depending on the flow speed measured by the microrobot. Such results could enable simple high-level control that could expand the development of microrobots toward applications in complex microfluidic environments.

scholarly journals PID Controller Implemented in Festo CDPX

2019 ◽  
Vol 260 ◽  
pp. 02008
Author(s):  
Primož Podržaj
Keyword(s):  
Control Systems ◽  
Pid Controller ◽  
Control Algorithm ◽  
Closed Loop ◽  
Pi Control ◽  
Programmable Logic ◽  
Educational Tool ◽  
Level Control ◽  
Loop Control ◽  
Machine Interface

In this paper, we describe the procedure for the implementation of the PID controller in the Festo CDPX operator unit. These units enable the execution of the control algorithm and human machine interface in a single unit. In our laboratory the unit is used to teach the students about the basics of control systems. For this purpose, one of the most common closed loop control systems for the education purposes was selected. It is a water level control system. In this paper the design of the whole system is presented. The need for a PI control algorithm is also explained. The programming of the operator unit CDPX, both in Festo CoDeSys and Designer Studio is explained. Such a simple system has turned out to be a great educational tool for Control Theory and Programmable Logic Controller related subjects.

EVALUATION OF CLOSED-LOOP CONTROL SYSTEM FOR RESTORING STANDING AND SITTING FUNCTIONS BY FUNCTIONAL ELECTRICAL STIMULATION

2005 ◽  
Vol 17 (01) ◽  
pp. 19-26 ◽  
Author(s):  
CHENG-LIANG LIU ◽  
CHUNG-HUANG YU ◽  
SHIH-CHING CHEN ◽  
CHANG-HUNG CHEN
Keyword(s):  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Closed Loop ◽  
Spinal Cord Injuries ◽  
Control Method ◽  
Control Strategies ◽  
Evaluation Process ◽  
Closed Loop Control ◽  
Loop Control ◽  
Loop Control System

Functional electrical stimulation (FES) is a method for restoring the functional movements of paraplegic or patients with spinal cord injuries. However, the selection of parameters that control the restoration of standing up and sitting functions has not been extensively investigated. This work provides a method for choosing the four main items involved in evaluating the strategies for sit-stand-sit movements with the aid of a modified walker. The control method uses the arm-supported force and the angles of the legs as feedback signals to change the intensity of the electrical stimulation of the leg muscles. The control parameters, Ki and Kp, are vary for different control strategies. Four items are collected through questionnaires and used for evaluation. They are the maximum reactions of the two hands, the average reaction of the two hands, largest absolute angular velocity of the knee joints, and the sit-stand-sit duration time. The experimental data are normalized to facilitate comparison. Weighting factors are obtained and analyzed from questionnaires answered by experts and are added to evaluation process for manipulation. The results show that the best strategy is the closed-loop control with parameters Ki=0.5 and Kp=0.

scholarly journals Neural Network-Based State Estimation for a Closed-Loop Control Strategy Applied to a Fed-Batch Bioreactor

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Santiago Rómoli ◽  
Mario Serrano ◽  
Francisco Rossomando ◽  
Jorge Vega ◽  
Oscar Ortiz ◽  
...  
Keyword(s):  
Neural Network ◽  
Closed Loop ◽  
Rbf Neural Network ◽  
Control Strategies ◽  
Tracking Error ◽  
Closed Loop Control ◽  
Online Information ◽  
Fed Batch ◽  
Loop Control ◽  
Batch Bioreactor

The lack of online information on some bioprocess variables and the presence of model and parametric uncertainties pose significant challenges to the design of efficient closed-loop control strategies. To address this issue, this work proposes an online state estimator based on a Radial Basis Function (RBF) neural network that operates in closed loop together with a control law derived on a linear algebra-based design strategy. The proposed methodology is applied to a class of nonlinear systems with three types of uncertainties: (i) time-varying parameters, (ii) uncertain nonlinearities, and (iii) unmodeled dynamics. To reduce the effect of uncertainties on the bioreactor, some integrators of the tracking error are introduced, which in turn allow the derivation of the proper control actions. This new control scheme guarantees that all signals are uniformly and ultimately bounded, and the tracking error converges to small values. The effectiveness of the proposed approach is illustrated on the basis of simulated experiments on a fed-batch bioreactor, and its performance is compared with two controllers available in the literature.

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