Learning-Based Nonlinear Model Predictive Controller for Hydraulic Cylinder Control of Ship Steering System

Round 1

Reviewer 1 Report

Figure 1 should be in a separate section. The first sentence of chapter 2 should come before figure 1 because the introduction to figure 1 in the text is missing (first text about figure 1 and next the figure 1).

There are no descriptions of the components used in the construction of the hydraulic system (i.e. type and parameters: pump, bypass valve, actuator (hydraulic cylinder), etc.) and, in particular, no basic information about the directional valve (solenoid valve), i.e. whether it is a proportional valve or a servo valve and what are its technical parameters (nominal flow, control current range, etc.). If it is a proportional valve, what type of spool does it contain? This is important for a system with an actuator (cylinder), as the flow rates to and from the actuator are, after all, different and it is recommended that the pressure drops in the solenoid valve on both flow directions are the same. 

The diagram shown in Figure 1 should include:

1) symbols for the physical quantities, i.e. p1, p2, ps, po - draw at which point in the system they are measured (pressure gauge symbols);

2) symbols for the flow rate in the valve, i.e., qsv1, qsv2, qsv3, qsv4;

3) the damper symbol b (because b is mentioned in the formulas in the text);

4) designation of mass m (load) and spring stiffness k;

5) designations of the piston area in the actuator.

Formulas (1): are indeed Cd and w1 the same in the formulas for qsv1, qsv2 and qsv3 and Cd in qsv4? What is D1 (delta), D2, D3 and D4 in formulae (1)?

Section 2.2:

1)      you would need to show a diagram of the hydraulic system with "Solenoid Valve Working at Left End". It might be worth expanding Figure 1 - add item b) and let what is there be a), and "Solenoid Valve Working at Right End" be item c);

2)      the pressure of the right working chamber p2 is never equal zero when the cylinder is moving!

Section 2.3: similar to section 2.2 the pressure of the left working chamber p1 is never equal zero when the cylinder is moving!

 

Furthermore, in the 'Introduction' it is worth writing in one sentence that proportional valve systems can be powered not only by variable displacement pumps but can also be powered by fixed displacement pumps, such as piston pumps, gear pumps or satellite pumps [for example https://doi.org/10.1016/j.acme.2019.04.003].

Author Response

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Reviewer 2 Report

Please read the attached file. Thank you.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf