Layout Design and Verification of a Space Payload Distributed Capture and Lock System

Round 1

Reviewer 1 Report

The paper is interesting and worth to publish after minor corrections.

 

11.      Please check the language especially in Abstract. There are some grammar errors. Please analyze also the language to have more scientific soundness.

22.      Please check the names used in the books related to space robot or space stations and use them when referring your subsystems. For example “active end capture” defined in abstract is the name completely unknown for me.

33.      Please check the content of the abstract with Introduction. In Introduction there is a sentence “This paper aims to improve the tolerance capability of the capture system to obtain high-reliability capture, the positioning and layout of the capture system are designed, and the configuration of the capture system is designed and parameter optimized” which well describe the content of the paper. The abstract is much less clear in this context.

44.      Please provide explanation why the Cardan Angle are used in the paper. In Aerospace much more often the Euler angles or quaternions are used.

55.      The structure of the paper should be corrected. In my opinion the section 2 is too large and very detailed (19 pages over 28 of whole paper)– maybe it is worth to divide section 2 for two separate ones. At the end of Introduction there should be a section where the content of the paper is shortly described. This would allow reader to go smoothly through the paper.

66.      The major point is lack of clear information about the novelty of this paper. To do this clearly first the maneuver assumptions should be clearly stated. For example it is not fully clear if the payload is connected to platform through the manipulator arm or it is free floating. It seems that it is a first case – it is so called fixed base approach in space robotics. If this is a case the difference between your system and many solutions well known from terrestrial/industrial conditions must be highlighted. If the space manipulator is a main source of error (due to its lightweight, low stiffness, low free frequency) and these error are different than in terrestrial case – there should be provide a reference proving such situation.

77.      In eq. 9 there is provided algorithm to plan trajectory of the capture system on position level –  the manipulator arm quite often are controlled on velocity or torque level – please discuss the singularities of this trajectory as well as if the curve is smooth in mathematical sense.

88.       Please check if tests described in section 3 is somehow comparable to simulation described in section 2.  Eventually please discuss comparison of them.

Author Response

请参阅附件。

Author Response File: Author Response.pdf

Reviewer 2 Report

This article describes the parametric design of a mechanism for the capture and lock of space payloads. A mathematical model was developed, and some experimental activity was carried out to verify the tolerance capability of the system.

The article starts with a good review of the state of the art, mentioning veracious academic publications, however systems for capture and lock, although slightly different, have already been implemented for example for the docking mechanisms for the capsules arriving at the international space station. So, I would like to see the literature review extended beyond the academic publication to briefly cover what is already in use.

Overall, the article is well written, but some words appeared to be mistranslated.

In the introduction line 35 & 36, the craft carrying the payload is called “aircraft” which seems inappropriate because when these manoeuvres will happen the craft will be in space, so maybe “spacecraft” (as they call it in section 2 line 114) line or just “craft” is more appropriate. Or perhaps “shuttle” as in figure 1 the craft looks very similar to the US’ “space shuttle”. Here the label for the craft says “Aerocraft” which different from aircraft, but still inappropriate for the same reason. So, the authors should decide an appropriate name for their craft and stick with it throughout the article.

In section 2, from line 111 onwards, referring to figure 1 the authors correctly call Payload a “container” (green square in the picture) which is transferred from the “craft” to the “space station”. Payload 2 (red square), which is retrieved from the space station at line 119 is called “abandoned” payload 2, to be released in orbit to crash into the atmosphere. However, in figure 1, Payload 2 is shown inside the craft, which contradicts the statement that payload 2 is abandoned to deorbit itself. If this is the case, in figure 2 there should be a final picture showing payload 2 offloaded from the craft and released in orbit, because as it is it looks that Payload 2 will return to the ground onboard the craft/shuttle.

On line 136 and for the rest of the article, the authors call the “payload”, just “load”, and this is quite confusing, as the term load is most often used also to mean forces or moments, whereas payload refers to the physical object, or item/container that is captured and moved by the robotic arm and then constrained. So, overall, the authors should stick with the term payload when they mean this physical object.

At line 225 the authors mention a “vertical” relationship… etc.. “Vertical” here does not mean much, and perhaps what the authors mean is perpendicular to the surface which contains the 4 other points?

From line 216 the authors mention “over-constraints” and “over-positioning”. I understand what they mean, but I wonder if it would be appropriate use terms like “hyperstatic” constraint to mean an over-constrained system (with the case of C=0 called isostatic constraint), when introducing this terminology, as the terms hyperstatic or isostatic constraint are well established and well understood.

The core or the article is well developed, and I appreciated the techical content, but in my opinion it is far too long, and the authors should try to be more concise in their explanations.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf