Optimal Speed Regulation Control of the Hybrid Dual Clutch Transmission Shift Process^†

Round 1

Reviewer 1 Report

The main topic of this paper is to present and provide a speed regulation control method that will achieve a rapid and robust gear shifting performance for a hybrid DCT. In lines [98-99] it clearly written that the target is to reduce speed regulation time and ensure smooth gear engagement.

My comments are:

Minor spelling mistakes should be checked. Editing of figures must be made in order to be readable and understood better, meaning that lines of graphs should be of different type not just different colors. In line [120-121] it is stated that the parameters can be experimentally estimated and are presented in Table 1. Explanation is needed on how these parameters were found. Also, which are the test cases mentioned in Figure 4. In lines [172-173] it is stated that the proposed controller is validated in a simulation platform (which?), with a high fidelity powertrain model. Where was this model found and why is it used? In line [175] it is stated that the acceptable speed difference is according to synchronizer bench test results? What are these results and found where? Equation 29 is used as a hypothetical disturbance, why this? Simulation results are just presented in graphs as a quality criteria of time, but a quantity criteria must be used to validate and compare. This would be a percentage for example. This kind of results cannot be accepted since they do not validate time reduction and smooth gear engagement mentioned as the target of this paper. The same comments, as in (7), exist for the experimental results. Just graphs, no other validation or explanation based on a specific quantity.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This work is about optimal speed regulation control of the Hybrid Dual Clutch Transmission Shift Process

This work deals with an important topic in gear changing mechanism which is speed regulation control of the unloaded motor. Since the motor is disengaged at this time, the speed control can be done based on modelling. This makes model-based controllers like MPC good candidates. Authors tried to add more to it and by using disturbance observer, help MPC in dealing with non-constant disturbances and uncertainties. The presented approach is based on some assumptions in the derivation of the controller that are acceptable. 

The novelty of this work is in the combination of the existing approaches, so in the sense of the type of the work. It is an application-based approach and does not have novelty in the sense of presenting a new idea.

The simulation results are limited and can be extended to include other approaches and show the result in comparison to the other works and known approaches like sliding mode controller, backstepping and adaptive MPC.

The paper language is sound, understandable with minor errors. Equations are clear and numbered correctly. Figures are in good quality and well presented.

These are points that are highly recommended to be addressed by the authors:

The literature review is not comprehensive enough. It needs to be improved with more control approaches in this area.
102: Equation 2, symbols need to be defined.
161: Adding relaxation variable \alpha is not justified. More explanation is required here.
161: Optimisation solutions have been referred to Wright's work however, it needs to be briefly explained in the context of this application. And which solution is used in this work?
167: Disturbance is assumed as slowly time-varying; however in a real application, it can have high-frequency component. Some discussion about the nature of the disturbance and uncertainties needed.
183: In the simulated disturbance does not have components relative to the speed. Simulation needs to be done with a disturbance non-linearly relative to speed as well.
190; Overshoot is still noticeable in the plot Figure 7.a. F what is the main cause of the overshoot and why the presented controller is not able to cope with it?
191: Comparison with other approaches like sliding mode control, adaptive MPC and back-stepping are recommended.
221: MPC+DO shows a good performance; it is encouraged to present the results in a table form.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

There are many changes according to first review suggestions that comply with reviewer comments, as so the paper in this form can sufficiently provide the information needed.

One comment to be examined is: At Figure 6, graphs (c) and (d) have wrong magnified pictures. I believe magnified part of (c) corresponds to (d) and vice versa.

Author Response

According to the reviewer 1’s comment, we have carefully checked the simulation results of Figure 6 and confirmed that the correspondence between graphs (c) and (d) is correct. Due to the large difference in the y-axis value range between original plot and partial enlarged view, the reviewer thought we had made an error. The ranges of the y-axis in graphs (c) and (d) are [-65, 15] and [-15, 65], while the range of the y-axis of the enlarged part are [-0.5, 0.5] and [-3, 1.5]. The reason for choosing different number scales is to see the trend of the curve more clearly. We hope that our explanation will be approved by the reviewer.