Orbit control device and satellite

Patent metadata

Field	Value
Publication number	US-2017369192-A1
Application number	US-201615540726-A
Country	US
Kind code	A1
Filing date	Jan 6, 2016
Priority date	Jan 9, 2015
Publication date	Dec 28, 2017
Grant date	—

Abstract

A satellite comprises thrusters disposed with the firing directions each facing away from the mass center of satellite and different from each other. A control amount calculator calculates control amounts of the mean orbital elements from the mean orbital elements and the temporal change rates of the mean orbital elements set by an orbit determiner, and the target values. A distributor calculates firing timings and firing amounts of the thrusters for realizing the control amounts of the mean orbital elements by expressing a motion of satellite with orbital elements, solving an equation taking into account coupling of an out-of-plane motion and an in-plane motion due to thruster disposition angles and thruster firing amounts at multiple times, and combining one or more thruster firings controlling mainly an out-of-the-orbit-plane direction and one or more thruster firings controlling mainly an in-the-orbit-plane direction.

First claim

1 : An orbit control device for a satellite provided with four thrusters disposed on the satellite with firing directions each facing away from a mass center of the satellite and different from each other, the orbit control device comprising:
an orbit determiner to determine mean orbital elements of the satellite and temporal change rates of the mean orbital elements; a target value setter to set target values of the mean orbital elements; a control amount calculator to calculate control amounts of the mean orbital elements from the mean orbital elements, the temporal change rates of the mean orbital elements, and the target values; a distributor to calculate firing timings and firing amounts of the thrusters for realizing the control amounts of the mean orbital elements calculated by the control amount calculator by expressing a motion of the satellite with orbital elements, solving an equation taking into account coupling of an out-of-the-orbit-plane motion and an in-the-orbit-plane motion due to thruster disposition angles and thruster firing amounts at multiple times, and combining one or more thruster firings controlling mainly an out-of-the-orbit-plane direction and one or more thruster firings controlling mainly an in-the-orbit-plane direction; and a thruster controller to control the thrusters based on the firing timings and the firing amounts calculated by the distributor.

2 : The orbit control device according to claim 1 , wherein
the control amount calculator comprises: a feedback control amount calculator to calculate feedback control amounts of the mean orbital elements based on the mean orbital elements calculated by the orbit determiner and the target values of the mean orbital elements set by the target value setter; and a feedforward control amount calculator to calculate feedforward control amounts of the mean orbital elements based on the temporal change rates of the mean orbital elements.

3 : The orbit control device according to claim 1 , wherein
the distributor calculates the firing timings and the firing amounts of the thrusters so that the number of thrusters simultaneously used is two or less.

4 : The orbit control device according to claim 1 , wherein
the control amount calculator calculates a control amount of a mean inclination vector, and the distributor calculates an argument of the control amount of the mean inclination vector, determines a south-north control firing timing from the argument of the control amount of the mean inclination vector, and calculates the firing timings and the firing amounts of the thrusters so as to implement a second south-north control a ½ orbit period after a first one of the south-north control firing timing, and control a mean eccentricity vector a ¼ orbit period or a ¾ orbit period after the first one of the south-north control firing timing.

5 : The orbit control device according to claim 1 , wherein
the distributor calculates the firing timings and the firing amounts of the thrusters so as to perform south-north control one time in one orbit period using a combination of two of the thrusters and perform east-west control two times in one orbit period using a combination of two of the thrusters.

6 : The orbit control device according to claim 5 , wherein
the distributor executes numeric search using the firing timings and the firing amounts of the thrusters calculated by the distributor as an initial solution, and calculates the firing timings and the firing amounts of the thrusters that eliminate use of one of the thrusters in at least one of the two east-west thruster firings.

7 : The orbit control device according to claim 1 , wherein
the control amount calculator calculates control amounts of a mean eccentric vector and a mean inclination vector, and the distributor presets a feasible timing of firing the thrusters in one orbit period, and determines the firing amounts of the thrusters for second to fourth times and whether the firing is possible based on the control amounts of the mean eccentricity vector and the mean inclination vector calculated for each timing by the control amount calculator.

8 : A satellite, comprising:
four thrusters disposed on the satellite with firing directions each facing away from a mass center of the satellite and different from each other; and the orbit control device according to claim 1 .

9 : An orbit control method for a satellite comprising four thrusters disposed on the satellite with firing directions each facing away from a mass center of the satellite and different from each other, the orbit control method comprising:
an orbit determination step of determining mean orbital elements of the satellite and temporal change rates of the mean orbital elements; a target value setting step of setting target values of the mean orbital elements; a control amount calculation step of calculating control amounts of the mean orbital elements from the mean orbital elements, the temporal change rates of the mean orbital elements, and the target values; a distribution step of calculating firing timings and firing amounts of the thrusters for realizing the control amounts of the mean orbital elements calculated in the control amount calculation step by expressing a motion of the satellite with orbital elements, solving an equation taking into account coupling of an out-of-the-orbit-plane motion and an in-the-orbit-plane motion due to thruster disposition angles and thruster firing amounts at multiple times, and combining one or more thruster firings controlling mainly an out-of-the-orbit-plane direction and one or more thruster firings controlling mainly an in-the-orbit-plane direction; and a thruster control step of controlling the thrusters according to the firing timings and the firing amounts calculated in the distribution step.

10 : An orbit control device for a satellite provided with a plurality of thrusters disposed on the satellite with firing directions each facing away from a mass center of the satellite and different from each other, the orbit control device comprising:
an orbit determiner to determine mean orbital elements of the satellite and temporal change rates of the mean orbital elements; a target value setter to set target values of the mean orbital elements; a control amount calculator to calculate control amounts of the mean orbital elements from the mean orbital elements, the temporal change rates of the mean orbital elements, and the target values; a distributor to calculate firing timings and firing amounts of the thrusters for realizing the control amounts of the mean orbital elements calculated by the control amount calculator by expressing a motion of the satellite with orbital elements, solving an equation taking into account coupling of an out-of-the-orbit-plane motion and an in-the-orbit-plane motion due to thruster disposition angles and thruster firing amounts at multiple times, and combining one or more thruster firings controlling mainly an out-of-the-orbit-plane direction and one or more thruster firings controlling mainly an in-the-orbit-plane direction; and a thruster controller to control the thrusters based on the firing timings and the firing amounts calculated by the distributor.

11 : The orbit control device according to claim 10 , wherein
the control amount calculator comprises: a feedback control amount calculator to calculate feedback control amounts of the mean orbital elements based on the mean orbital elements calculated by the orbit determiner and the target values of the mean orbital elements set by the target value setter; and a feedforward control amount calculator to calculate feedforward control amounts of the mean

Assignees

• Mitsubishi Electric Corp

Inventors

• Kitamura Kenji
• Yamada Katsuhiko
• Shima Takeya
• Suenobu Hiroshi

Classifications

• B64G1/242 Primary

  Orbits and trajectories · CPC title

• B64G2001/245

  Operations & Transport · mapped topic

• G05D1/0883

  Physics · mapped topic

• B64G1/26 Primary

  using jets · CPC title

• B64G1/244

  Spacecraft control systems · CPC title