Investigation of Hysteresis Effect in Torque Performance for a Magnetorheological Brake in Adaptive Knee Orthosis
Round 1
Reviewer 1 Report
The topic is worthy of investigation and the journal is suitable Unfortunately seems to be a scientific report for demonstatrator model with validation for different technology level.
In my opinion the manuscript need revision being not well organized with ten figures and not table with quantified results.
The 22 number of references are not enough to sustain the original character of idea and results taking into account that the recent publication are self citations.
I do recommendmoderate revision taking into account the above comments despite the fact that the format indicates only minor and major
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper deals with an experimental approach of studying hysteresis effect in torque performance for a magnetorheological brake in adaptive knee orthosis. A less energy-consuming PWM actuation signal is proposed to activate the proposed MR brake, which can power the MR brake to maintain steady torque through simulation analysis and experimental verification.
Generally speaking, the paper is well organized with sufficient details of the experiment. However, the following issues need to be improved:
- It is recommended that the format of symbols in the formula and the text be consistent.
- Figure 4 seems to fail to clearly show the structural characteristics of the MR brake. It is suggested to add figure to better show its structure.
- The Ansys simulation result in Figure 7 are slightly larger than the experimental result, with an error of 1.8 Nm. The results are very close. But the frictional torque is not considered in the Ansys simulation process. For the actual situation, I think the experimental results should be greater than that of simulations. The authors are suggested to improve the explanation for this error.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The magnetorheological brake as an alternative to the existing elements of the exoskeleton, in particular, knee orthosis, was investigated in the work. The novelty of the work is in the use of an alternating magnetic field in the operation of the MR brake and in experimental and numerical researches. All experimental results were obtained using modern equipment, so the reliability of the results is beyond doubt.
The Introduction section shows the importance and advantage of using MR brakes over existing ones. The article presents the research of MR brake under a pulse width modulation actuating signal, that is, an alternating magnetic field, compared with DC signal. The aim of investigation is to overcome hysteresis problem and to turn it into an advantage to save the power consumption of MR brake.
However, the work completely lacks the mechanism of magnetization of a magnetorheological fluid in AC magnetic field. The authors focused on the hysteresis properties of the core and describe the mechanism of static hysteresis. It should be noted that the mechanism of dynamic hysteresis, especially in smart systems such as MR fluids, is fundamentally different. The section about explaining the occurrence of hysteresis is an elementary truth and does not show the real device physics mechanism, which includes several types of magnetic susceptible materials. In addition, the mechanism of the appearance of hysteresis in MR fluids can not be related to the displacement of domain walls, since the fluid consists of micro-sized particles. It is worth considering the mechanisms of magnetization of particles in a carrier liqiud, as well as relaxation processes in alternating fields.
Thus, despite the engineering line of the work, where the hysteresis was taken into account and the torque of the MR brake in the dynamic case was calculated, there is practically no scientific physical basis in the work.
There is also a question about the appearance and absence of ripples at high frequencies. "At high frequencies, the current doesn’t have enough time to rise and decay to peak levels." - does this mean that the amplitude of the current and the corresponding field decreases? If so, what kind of comparison can authors talk about?
The work is written in generally satisfactory language, but some parts of it are very difficult to comprehend in terms of language. In addition, there are a lot of repetitions of the same thing in different sentences throughout the work.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
This paper lacks many information and explanations, which include the final concluded results to be raised suspicion. Therefore, it should be resubmitted after well-reconsideration with major revision by referring the pdf attachment.
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Thank you for the answer and the corrections. The new tables are especially meaningful and make the text easier to read. Thank you for the answer about MR fluid, the information is sufficient now.
Reviewer 4 Report
None.
