October 11 - 13, 2013 , Sinaia â Palace Hotel, ROMANIA. 1. Steering ... S - OK for first loop disturbances, problems for the second one!!! 17th International ...
Politehnica University of Bucharest
Department of Automatics and Computer Science
Steering control for multiple propulsion systems
Ciprian Lupu, Catalin Petrescu, Gabriel Florea, Mircea Lupu 17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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OUTLINE
... Sometimes the answer to questions is right next to us, closer than we think ...
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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OUTLINE
Introduction
Proposed idea
Experimental results
Conclusions
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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INTRODUCTION
Ratio control (RC) consists in keeping a constant ratio between two (or more) process variables, irrespective of possible set-point changes, and load disturbances that might occur on the plant.
RC is “present” in a variety of industrial applications such as chemical dosing, water treatment, mixing vessels, combustion systems .... But may be steering “process”…
x
y z
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
z=x+y x/y=ct. !!! 4
INTRODUCTION
The typical ratio control scheme (parallel (P) & series (S) control) :
P – problems in case of disturbances for the all loops!!!
S - OK for first loop disturbances, problems for the second one!!!
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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INTRODUCTION
Visioli’s proposed ratio control structures:
OK for all loops!!!
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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INTRODUCTION
Control structures: BS1, BS2 are “Blend Station” (BS), F1 and F2 coupling factors are dynamic systems F1(s) and F2(s), associated here to filtering components. For this approach F1 and F2 are considered constant included in (1.0 – 0.0) range. These two factors represent dependence of each system’ set point to neighborhood’s output. A lower value means important coupling (dependence). In the same time, for particular values F1 = 1 and F2 = 0 system presented becomes a classic series connection. 17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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INTRODUCTION
the same time, in in modern transportation case there are classes of
structures with multiple engines
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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INTRODUCTION
The problem to which there is trying to find an answer is in the case
that one of the engine of group A or B defects. The normal solution is to increase the reference of adjustment systems of the deficient group with a value depending to their numbers and
structural limitations.
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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PROPOSED IDEA
Using Visioli’s proposed control structure, with variable parameters:
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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PROPOSED IDEA
Using Visioli’s proposed control structure, with variable parameters: (variant)
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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PROPOSED IDEA
The operation of the structure in case of intervention has as a two step strategy: a) the general set point (r) change, b) the (a) ratio change.
=>maintain the same output for the unaffected group and correct the affected engines group situation (! If is possible!) 17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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PROPOSED IDEA a) general set point (r) change,
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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PROPOSED IDEA b) the (a) ratio change
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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PROPOSED IDEA 2x2 system exemple:
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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EXPERIMENTAL RESULTS
The comparative developed tests: a) a system with 4 engines (2x2) equipped with (only) control loops on each engine vs. a system equipped with two extra fixed BS; b) a system equipped with two extra fixed BS vs. a system equipped with two extra adaptive BS. !!! Even though the (2x2) option is less favorable from the practical implementation point of view, it was chosen because of the increased difficulty – losing a engine equaling a 50% perturbation. 17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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EXPERIMENTAL RESULTS
Experimental platform (Matlab simulators)
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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EXPERIMENTAL RESULTS
a) a system with 4 engines (2x2) equipped with (only) control loops on each engine vs. a system equipped with two extra fixed BS;
Signed ratio error integral evolution
The initial ratio – a - is considered equal to 2 and the set point is set to 1. After the systems stabilization, it is considered that reservoir E11 fail (sample 70). As balancing strategy, the a ratio is reset to 1 and the set point Absolut ratio error integral evolution value increased to 2. 17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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EXPERIMENTAL RESULTS
b) a system equipped with two extra fixed BS vs. a system equipped with two extra adaptive BS.
Signed ratio error integral evolution
The initial ratio – a - is considered equal to 2 and the set point is set to 1. After the systems stabilization, it is considered that reservoir E11 fail (sample 70). As balancing strategy, the a ratio is reset to 1 and the set point Absolut ratio error integral evolution value increased to 2. 17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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EXPERIMENTAL RESULTS
Experimental platform (2 software applications) •General set point •Set point mixing •Connection with controllers
Interface of real-time controller component
Group A:
Group B:
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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EXPERIMENTAL RESULTS
Experimental platform (real time evolutions)
set point change
Fault rejection
Ratio change (a) – from 0.8 to 1.2 17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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CONCLUSIONS
As a general conclusion the proposed structures ensures superior performance versus the simple multiple parallel controls.
In structural disturbances as engines fail, the value which modifies the ratio factor is 1/N, where N is the number of engines / wheels / propellers of the same side. If N is bigger the bump is smaller and the precision better.
In practically exploitation there are identified two distinct cases: the first one, where products A and B are used directly, without mixing; and second one, where A and B are intermediary mixed in an auxiliary tunell. For the second situation the integration of the signed value of ratio error is the most adequate criterion and for the first one, the integration of the absolute (modulo) value of ratio error criterion is better.
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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CONCLUSIONS
In the a) tests using an adaptive ratio -> provides an improvement of the ratio error of about 7-10% on both criteria.
In the b) tests using an adaptive ratio and F1, F2 parameters -> provides an improvement of the ratio error only for the signed error criteria. This fact recommends it on the supplementary mixing tunnel.
Real time tests complete the conclusions with some interesting results:
So, during laboratory tests there was identified a special situation, when wanting to turn off the system by imposing a general reference to a null value, one of the engine did not stop completely (a situation which is impossible in simulation). The implemented mixing system kept the appropriate reference flow parallel group so that the error report to be as close to 0. As a result, the global system does not stop. This observation could be included in the corresponding standard exploitation (ISO etc.) to be solved on the Safety hierarchical level. 17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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Thank you! Steering control for multiple propulsion systems
17th International Conference on System Theory, Control and Computing – ICSTCC 2013 October 11 - 13, 2013 , Sinaia – Palace Hotel, ROMANIA
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