Stroke Kinematics Analysis and Hydrodynamic Modeling of a Buoyancy-Supported Water Strider Robot^†

Round 1

Reviewer 1 Report

This paper presents the development and experiment of a water strider robot with floats and paddles. The authors analyzed the speed, power and moving efficiency of the robot based on Newton’s second law and hydrodynamics. They also estimated several parameters in the hydrodynamic model through a CFD method and an experiment. The authors investigated the forward speed and turning performance of the robot in a water tank. This paper is interesting from an engineering point of view. However, since the propulsion and float principles in this paper are different from those of real water striders, it is doubtful whether it is suitable for Applied Sciences Journal from a scientific viewpoint. The authors should discuss the advantages of the developed robot from a scientific viewpoint.

 

This reviewer has several questions.

 

Why did the authors select the paddle motion (spatial trajectory) with a certain speed pattern (Fig. 5)? Do the spatial trajectory and its speed pattern have a great influence on the motion performance of the robot? Did the authors select the paddle motion based on Eqs.(14) and (15)?

 

The authors only compared an ellipse-like spatial stroke trajectory and a rectangle-like spatial stroke trajectory. How did the authors select the spatial trajectories? This reviewer thinks that the motion performance of the robot will change depending on the size of the ellipse (the lengths of the principal axes of the ellipse)(spatial trajectory) and its speed pattern.

 

Does the size of the floats (the lengths of the principal axes of the ellipsoid) affect the propulsion and resistance? Is all the driving force generated by the paddles?

 

In these regards, this reviewer thinks there are few scientific findings from the obtained results.

 

In Eq.(9)

What is the work point of the robot U_0? Is U_0 a speed of something?

 

In Eq.(16)

What does “h” stand for?

 

In Eqs (24) and (25),

b1 -> b_1 (subsript)?

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The paper is aimed at the design and analysis of water strider like robot. It contains state-of-art review, description of the robot design, kinematic analysis of paddle motion, description of the hydrodynamic modelling approach and certain experimental verification. In my opinion the paper is quite well written with suitable structure and correctly chosen analysis approaches. The significance of the paper could be in the complex description of various hydrodynamic forces acting on a paddle and in certain kind of experimental verification. I recommend to publish the paper after these minor improvements:

1) The research in the paper suppose that both linear stepper and stepper motors will generate their motion exactly and will not be affected by paddle dynamics etc. Is this correct also in reality and is the control of the motors robust enough?

2) The equation of motion is formulated only for one degree of freedom (translational motion of the robot). Is this simplification correct? I would expect that the robot will move also in vertical direction.

3) Please, add more computed results to section 5.2 concerning the verification of the whole robot motion. There are not any theoretical results.

4) What is further usage of the proposed computational model? There are very few results in the paper coming from the model.

Author Response

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Author Response File: Author Response.pdf