Adapt or Perish? Exploring the Effectiveness of Adaptive DoF Control Interaction Methods for Assistive Robot Arms

Round 1

Reviewer 1 Report

The manuscript describes a user study of different user control strategies for assistive robot arms.  The study was performed using VR, which allowed for testing of augmented visualization of anticipated robot motions.

The paper is very well written. The study results include objective measured (timing of the tasks) and subjective reports, including the thematic analysis of subjects' voice messages. Although the study did not confirm all of the hypotheses, the report is valuable for the area of HCI for assistive robotics.

There are no major complaints. The authors comment on the differences/limitations of performing the study in VR as opposed to real world that would require use of AR (which is still limited). Could you comment on how such transition would apply to the input device? Users in the study used the VR handheld controller. It is assumed that subjects were likely quite familiar with the controller. Do you have any intuition whether the input device itself would have any effect on the ease of use in different control modes?

Author Response

Dear Reviewer 1,

We thank you for your thoughtful feedback. We are glad that you had “no major complaints” and are happy to answer your question about different input devices.

We designed our control types with simple input devices in mind. Specifically, we designed for features that should be achievable with most input devices, namely two Degrees of Freedom and a button. Since we did not use any special features of the Oculus Quest Motion Controller (like 6-DoF positional tracking), we assume that the control types should work just as well with different input devices. It is still possible that our assumptions are wrong, so we have added a short passage in the limitations section of our paper:

“Additionally, our study involved the use of the Oculus Quest system and the Oculus Quest Motion Controller as the only input device. In the real world, however, assistive robot arms can be controlled with a wide range of input devices, depending on the abilities and preferences of the person using them. We specifically only used the most basic functionality of the Motion Controller (the control stick and one button) to ensure that the results are also applicable when using a different input device with two input axes. It is still possible that the use of different input devices might add more complexity to the overall usage of such a system.”

In addition to the changes above, we corrected English language and style issues with the help of native speakers. We have also made it more clear that our paper can be read and understood independently of our previous work, even if it is an extension of it.

We appreciate the valuable feedback.

Reviewer 2 Report

Review

(technologies-1564689)

The main contribution of this paper is to extend an already existing research on assistive robot arms from 2D to a 3D environment as well as the understanding of the benefits and challenges of the examined three control types. However, I did not find a clear description of the study objectives in the manuscript, which would give a more straight forward focus of the study. The topic presented in the study is very interesting considering current developments in the areas of demographic change and digital transformation, and promising insights can be drawn for assistive environments for individuals with motor impairments and/or those with a frail health condition. Yet, in my opinion this manuscript needs editing before it can be published.

This paper is quite lengthy and at some points tedious to follow. It would benefit from being shortened in places that are repetitive or describe procedures from previous work, referring only to the current study. On the other hand, I miss some information that should be complemented for a better comprehension. In the following, I mention my comments/suggestions after respective sections.

Introduction sections: The procedure is very much based on the previous work of the authors and yet the processes and constructions are explained in very much detail. Many references to the earlier work of Goldau and Frese (2021) in the manuscript let arise the impression that without having read the previous article(s), there is little chance of success in dwelling on the current one (and the referencing of the previous work also needs improvement in this paper). As a reader, I would prefer an independent work in which concrete information about the current study is given, and I can decide by myself whether I read the previous work or not. On the other hand, the (international) research in this field and the possible applications of the technology are described only very sparsely. Embedding the study in the assistive context is also missing in order to better understand the added value of the use of the assistive robot. Thus, I suggest that the authors anchor their work more clearly in this context.

Method: According to the described specific recruitment procedure, the study is carried out with participants who are probably very technology-savvy and can handle such technically ambitious devices very well. This is probably not representative for users who really would need such technology. But this fact is also reflected accordingly in the Limitations. In addition, the authors should mention in this Section that besides quantitative methods they also use qualitative methods and describe these appropriately. Other small remarks refer to the following:

• In my opinion, the authors shouldn’t describe the tasks used by the previous research of Goldau and Frese. Instead, they should inform how -- based on this previous work -- the tasks were concepted in their own study.
• For the hypotheses and also later for the results it would make sense to enter the time units.

Results:  Basically, the results are appropriately described and clear. I very much like the fact that both a qualitative and a quantitative analysis of results has taken place here.

It is important to refer to each table and each figure in the text while describing the content to be found there. In addition, whenever possible the tables and figures should be described first and then appear in text.

Discussion: In this Section, results are only discussed in relation to the formulated hypotheses. This is in my opinion not enough. On the one hand, I would expect more references to the findings resulting from the qualitative data. On the other hand, I also miss the broader reference of the presented study to the research conducted in this area as well as the reference to the real life with all the practical fields of application that could be enabled by this technology.

The manuscript is basically well written, but it will significantly benefit from a proof-reading of a native English speaker. There are many (very) long sentences in the paper, and some passages are quite bumpy to read (especially the use of tenses) and unnecessary complicated. In addition, the manuscript contains a lot of a redundant content, which should be cut off. The punctuation should be improved in the whole document. In the following are some examples for my personal issues with reading the document:

• Here is an example of a sentence, which I not fully understand: “The explanation of each control type was followed by a series of trials of our task the participants had to execute in order to progress through the study.”
• Example of a long sentence (without the necessary interpunction), which is difficult to read: “Participants were informed that during the study certain metrics and usage data such as task completion times will be recorded and sent to our servers, that they need to fill out a short questionnaire after each condition of the study, that they would be able to record a short audio message after each condition and that cookies were used on our website.”
• I found also some orthographic mistakes (e.g., “human-computer-interface “, “counter intuitive”, “2D-study”, etc.) and syntax issues (e.g., “interaction effect… suggest…”)
• Many abbreviations are not explained bevor using them.

My advice is: Simplify the language, shorten the sentences, and let a native speaker proof-read the manuscript.

Comments for author File: Comments.docx

Author Response

Dear Reviewer 2,

We thank you for your thoughtful feedback. You have raised valid issues and we already included the following improvements to the paper to alleviate these concerns.

1 - A clear description of the study objectives

In line with your suggestion to more clearly state the objectives of the study, we have included the following statement in the Introduction section:
“The goal of this paper is to explore the proposed novel control method, as well as possible visual cues for the DoF-mappings. In particular, we want to explore how the novel adaptive control method performs in a 3D environment compared to the standard mode switch approach with cardinal DoF-mappings, and whether changes in the visual cues have an impact on the performance of the adaptive control method.”

2 - More independence from the original study

We have significantly reduced the descriptions of the original study, including the description of the task used in our previous work. However, we have left any information we deemed necessary to understand both our proposed control types and to compare our results against the results of the original study. Since these changes are substantial and are positioned at various points in the paper, we have marked them within the text. 

3 - Improving the Related Work section

We have described previous research about assistive robots in the Related Work section to give more context about the field in general. We focused on the possible applications of assistive robots, specifically assistive robot arms.

“To assist people with physical or cognitive impairments, prior research often suggests possible solutions that use robots that automate specific tasks [7-10]. Assistive robots are found in a variety of designs. There are stationary robots specifically designed for meal-assistance [11], socially assistive robots for elderly people and people with cognitive impairments [12], navigational robots for blind people [13], and many more examples, both in research and commercially. Besides stationary robots (e. g. fixed to a table) [14], there are also moving robots attached to mobile platforms [15, 16], or mounted to the user's wheelchair [9].

To help people with motor impairments, assistive robot arms are widely used, both within the workspace and in performing ADLs [17]. Their flexibility allows for many different applications, such as feeding assistance [18], fetch and pick-up tasks [15], and cataloging of books [7].

Robotic assistance is generally well received by people with motor impairments. Drolshagen et\,al. found that people with disabilities quickly accept working with robots, even if the robots are in close proximity [19].”

4 - Clearer description for recording of qualitative data in the Method section

We have added a short passage describing what methods we used to analyze the qualitative data provided by the participants via voice messages in section 4.5. Study Design:

“In addition, the participants could record a short description of their experiences in the form of a voice message, although this was not mandatory. The recorded voice messages were transcribed and analyzed by multiple researchers to identify underlying themes and common impressions the participants had while using the virtual robot arm (see Section 5.2).”

5 - Improving the Discussion section

We have added to the Discussion section by discussing themes discovered during the thematic analysis of qualitative data, providing possible improvements to our control methods, and describing future applications of our control methods.

“According to some participants, using visual cues in a 3D environment caused problems with perspective. This made it difficult for them to predict how the robot would move, even with the visual cues provided by the arrows. To mitigate this problem, our concept might be combined with a “digital twin” of the robot arm, which demonstrates the movement virtually before the real robot performs it physically [31].

To improve the overall predictability of the system, both regarding the suggested modes and the movements of the robot, a training mode could be implemented. In this mode, the users would be able to teach the system the way they want specific tasks to be performed [32]. This should increase predictability, as the participants would know the proposed movements will be (partially) based on their own instructions. In addition, Spatial Augmented Reality can help the user's understanding of the robot's perception, e. g. which object the robot assumes the user wants to interact with [33]. In combination with the already implemented visual cues, this can help the users predict the robot’s movement more accurately.

After further research and refinement of our proposed control methods, they might allow assistive robot arms to help with ADLs that currently require the help of caregivers or more complex robots, such as dressing [34] or bathing [35]. The fact that the users always stay in control of the robot, while the robot performs more fluent, natural movements could also allow people with motor impairments to use the robot in social situations, e. g. at the workplace [36].”

6 - Style and Language

1. Tables and Figures: All tables and figures are now referenced before their appearance in the paper. 
2. Repeated Content: We have reduced repeated content as much as possible. However, in some instances, a short description of content that will follow is necessary to understand a certain section of the text. In these instances, we have reduced the amount of information to only that which we deemed necessary for understanding.
3. Language: We have corrected many issues with the help of two native speakers. These changes are not explicitly marked in the text as most of these were quick fixes, e.g. adding a comma or splitting a sentence into two.
   
   

We appreciate the valuable feedback.