Model Predictive Control-Based Attitude Control of Under-Actuated Spacecraft Using Solar Radiation Pressure

Round 1

Reviewer 1 Report

1. Why a heliocentric orbit? The applicability is very narrow. The most common orbits are geocentric.

2. Since you consider heliocentric orbits, for which the period is very long, do you need to consider the orbital angular velocity?

3. Equations (4), (5) and (6) are referenced from [24], which does not contain these equations. Please cite the correct paper.

4. Please provide a reference for the SRP expression in equation (8)

5. How is the assumption that the solar panel inertia can be ignored, reasonable? Don't you need a large surface area to be able to generate enough solar pressure torque to assist the two wheels?

6. to obtain your state equation (19), you already assume small angles and rates to linearize the kinematics and dynamics. The only nonlinearity you retain is in the expression for the SRP torque. Why not linearize the SRP torque also at least with respect to the Euler angles? 

7. The MPC algorithm presented on pages 9 to 11 looks fairly standard. Are there aspects of it that are an original contribution of this paper, or is it taken from another source? If so, cite the source

8. Equation (31) is a continuous-time linear system, while (32) is a discrete Lyapunov equation, using the same A matrix. Shouldn't you use a matrix exponential of AT, with T the sample period, or some approximation of it?

9. What is the practical significance of the disturbance torque in the simulation on page 20? Is it reasonable given the actual disturbance torques present for the given spacecraft in the given orbit?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper proposes an attitude control algorithm based on model predictive control for an under-actuated spacecraft by using the solar radiation pressure. The solar radiation pressure torque is used in favor by rotating the solar panels.

The topic is interesting yet the references are very old. There is no citation from the last 5 years and only 6 references from the last 10 years. The authors need to review the literature thoroughly.

The authors considered a spacecraft in a heliocentric orbit with no close planets in the field of view. Therefore, albedo was not taken into account. However, that would be good to give comments on this issue in the paper e.g. how much would you expect that the albedo affect the results?

In Equation (16), the system state equation is given. Can you please provide information on the measurement model as well?

Are the states directly measured?

The times can be marked at where the switching control happens e.g. on Figure 6.

There is no explanation for Figure 9, Figure 15.

Minor points can be listed as,

- In Equation (1), it should be /omega_o not /omega_0.

- Page 4, Line 126: "... in many literatures." should be like "... in many research papers."

- On Page 15, Line 404, it should be "Figure 5-Figure 8"

- On Page 18, Line 443, an error appeared.

- On Page 18, Line 449, it should be "Figure 16-Figure 17"

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors did all the necessary revisions pointed out by the referee. It can be accepted in this form.