JPH01500308A - How to control the attitude of a rotating body in orbit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] How to control the attitude of a rotating body in orbit The present invention relates to stabilizing the rotation axis of a rotating orbital body, and in particular to an active stabilization mechanism. The present invention relates to a method for stabilizing a rotating body without relying on mechanisms.

2. Explanation of related technology In known methods of attempting to stabilize the orientation of orbiting bodies such as artificial satellites, various Active means are commonly used. The most common of these means is stable figure target body mass to produce the desired precession of the axis of rotation of the body that maintains the direction of rotation. and some form of mass displacement to produce attitude control moments that interact with the geometry. This is the use of thrusters that utilize power.

Another stabilization method found in the prior art is the precession of the rotating axis of the orbital body. a magnetic moment that reacts with the Earth's magnetic field to produce a control torque for movement The use of electrical energy or magnetic fields to produce

Therefore, in order to generate and maintain the desired torque moment, these known followers are The current method is to determine the effective payload and Requires additional complexity, weight and energy consumption which reduces performance and efficiency.

These known prior art methods are useful for relatively short-lived orbital bodies and missions. is sufficient, but with the inevitable trade-off in weight, complexity and energy consumption. This case of establishing a permanent orbital body like a space station in Earth orbit The goal is to reduce payload weight and reduce weight, complexity and energy consumption. New stabilization methods and systems yield greater reliability of operation at reduced levels. All systems that require this system place unique demands on efficiency.

Therefore, each of these known methods has a number of drawbacks, which are This is overcome in the practice of the present invention. In particular, the desired orientation of the body is smooth is generated without the use of fuel or mass evacuation, and therefore the attitude control fuel or eliminates the need to carry propellant. The desired orientation of the body can also be determined by the electrician, generated without the consumption of energy or the development of some kind of magnetic field, and thus the energy of the orbital body. Greatly reduces Rugi requirements. The desired orientation of the body is determined by the control system error signals are generated without the need for attitude sensing equipment, thus reducing costs. reliability is improved. Finally, the system configuration implemented in the method of the present invention As a result of the geometry and configuration, the desired attitude of the rotating body is passively maintained and the rotation The maximum excursion of solar angle from the equatorial plane of the body is appropriate due to the solar array effect. is kept small.

Summary of the invention The present invention satisfies the aforementioned need for reduced weight, complexity and energy consumption. for passively stabilizing a rotating body in a fixed direction set to provide a method.

The invention relates to the mass shape, rotational speed, direction and defined shape of the trajectory of the spacecraft body. Implement a unique method of selecting. This orbit does not need to be on the equator or It is not necessary that the attitude direction be perpendicular to the road surface. Furthermore, the method of the present invention Allows passive persistence of the desired attitude and maximizes the solar angle excursion from the equatorial plane of the rotating body. The scarsion remains appropriately small for solar array effects or antenna gain. held.

Therefore, the present invention uses orbital inclination i5 orbital velocity Ω0 and node as its orbital parameters. To passively stabilize the attitude of a rotating orbital body with a retrograde velocity of the orbit line of mode γ. The rotational axis direction angle φ0 of the body is related to the method of remains essentially fixed and stable with respect to the body's orbital plane even when in motion It is. The axial direction φ0 is the north pole in the plane formed by the north pole and the orbit normal. is the angle of the axis of rotation from .

This method was determined by the ratio of the body's rotational inertia to the body's lateral inertia. Select the mass shape σ for the body and make sure that the rotation direction angle φ0 for the body is It involves choosing the rotational speed Ω for the body to be an equilibrium solution of the relation.

φo = arc tan (Zo / yo) + i-π/2 where xyz The orbital coordinate system has 2 along the orbital vertical axis and X at the ascending node, and the following relationship is keep.

xOkakuO yo = (z□ sin i) / (cos i-k z) zo is forte This is a quartic solution.

ni2z04-2kcos i ZO3 + (1- to 2) zo2 12kcos i Z□-cos” 1-Ok is defined by the following formula. is a constant.

k-1,5 ((cy-1)'/σ) (Ω02/Ωγ) by rotation direction angle φ0 Orient the body in orbit first. Determine the direction angle φ0 jtL　X　Q　s yQ and Z□ are the components in the xyz system of the unit vector along the body rotation axis It is.

Brief description of the drawing A better understanding of the invention may be obtained from consideration of the detailed description in conjunction with the accompanying drawings below. Ru.

FIG. 1A shows a satellite-like satellite whose axis of rotation attitude is passively maintained in accordance with the present invention. Shows the relationship between orbital bodies.

Figure 1B shows the top view with respect to the axis of rotation and the position of the trajectory normal at different times. Figure 1A is a view similar to that of Figure 1A, viewed from above.

Figure 2A shows the orbital method generated by the oblateness of the Earth. FIG. 3 is a diagram illustrating changes in satellite orientation resulting from retrograde motion of a line;

Figure 2B is a view similar to that of Figure 2A from the top.

FIG. 3A is a diagram illustrating retrograde motion of the rotation axis of the artificial satellite.

Figure 3B is a view similar to that of Figure 3A from the top.

FIG. 4 is a diagram illustrating the coordinate system definition used in this explanation.

Figure 5 shows the space station configuration with an orbit altitude of 500 km and an inclination of 28.5°. FIG. 2 is a graph of the average axis of rotation angle φ0 as a function of rotational speed for use; FIG.

Description of the preferred embodiment The essence of the invention is that the orbital body mass properties (body inertia and shape), generation, and the subsequent inertial motion of the axis of rotation is the total radiation of the sun's rays from the equatorial plane of the rotating body. The precession is continuously passively followed by the motion of the orbital plane when we also limit the excursion. lies in the unique initial orientation setting of the body in such a trajectory. System This unique device from Lement is shown in the basic system diagrams in Figures 1A and 1B. explain.

As illustrated in Figures 1A and 1B, the axis of rotation is the Earth's polar axis and orbital axis. It is fixed at a constant angle φ0 with respect to the north pole on the plane defined by the road plane standard. . If the axis of rotation is initially placed in this position, then if the angle φ0 is chosen exactly , remains vaguely intact, even if the orbit itself is precessing. Furthermore, times The axis of rotation is set so that small errors in the initial alignment remain vaguely small. It is established. Therefore, if the axis of rotation is placed at the correct initial angle φ0 in the first place, , a fixed position in the Earth axis/orbital plane without dependence on fuel or energy consumption. passively maintained in place. This angle φ0 is 2 as defined by the following relational expression. is a function of two parameters i and k.

i-orbital inclination k −1,5 ((cy-1) / cy) (Ωo2 / Ωte) in the formula σ - (rotational inertia of spacecraft) / (lateral inertia of spacecraft) Ω〇 - orbital speed Ω rotation speed Retrograde velocity of the Chi Node orbit line In carrying out the method of the invention, the angle φ0 has a suitable thickness over the mission life. The desired orbital parameters of the reference above are made small enough to generate solar cell power. Mass shape and rotational speed of the body consistent with the meter (i + Ω0゜ and Te) (σ and Ω, respectively) and at the start of the mission It is important to position the spacecraft's axis of rotation in the correct direction.

In a preferred embodiment of the method of the invention, the rotational axis angle φ0 is defined as follows: I can't stand it. Due to the spacecraft in an orbit tilted with respect to the equatorial plane, the oblateness of the Earth is reversed. Precession about the north/south pole axis in the row direction produces an orbital normal.

This retrograde motion is shown in Figures 2A and 2B. In addition, there is cotton on the body. If the body is rod-shaped, i.e., the gravitational gradient torque is less than 1. in the positive direction if it has a pitch-to-lecture ratio, and if the body is disc-shaped Precession is caused in the opposite direction around the orbital normal. For disc type The method is shown in Figures 3A and 3B.

These two precessions generally occur if mass and/or energy This would cause the spacecraft's axis of rotation to wander over a wide range of space if not spent on blocking. wake up

Another approach, and the basic principle of the method of the present invention, is that the precession is and allow passive maintenance of the rotational axis attitude in a valid known direction as shown in FIG. 1B. Therefore, it is advantageous to define the spacecraft and orbit parameters to combine.

This preferred coupling ensures that the gravitational gradient offset motion of the axis of rotation is shown in Figures 1A and 1B. To produce a planar equilibrium form such as achieved by placing the axis of rotation between the north pole axis and the orbital normal in such a position that the will be accomplished.

2 and ascending nodes along the trajectory normal axis to obtain the method of the invention mathematically. Consider a rotating xyz orbital coordinate system as shown in FIG. Celestial body x The angular velocity of this system with respect to the yz system is as follows.

The equation of motion for the angular moment vector h of the spacecraft satisfies the following relational expression: do.

(dlH/dt)+Hx%-Engine G (2) Equation (2) Intermediate G-Gravity Gradient Torque.

The gravitational disturbance torque is small and it takes a long time to move the h vector considerably. To give the governing equation of motion for this system, replace by its average value on the orbit (In the equation, C is the rotational inertia of the spacecraft and A is the gravitational force about the center of the spacecraft.) This is lateral inertia.

U indicates a unit vector.

The above equation can be rewritten as follows.

x' = (kz-cos i) y+z sin iy' = (cos i -kz) x' -d/dψ, ψ-tet k-1,5 ((cr-1)/a) (Ω2/Ωte) and σ-C/A These equations (5) consist of two first integrals, namely x2+y2+22-1 y-(kz2/2stn　1)-zcot　i+c1 and the equilibrium solution, i.e. x□　−0 It has yo − (zOsin i) / (cos i-k z). z□ is below Quartic relational formula % formula % below The average rotation angle φ0 is determined from the following average equation.

φ0-arc tan (zo/yo) 10i-π/2φ. parameters of The dependence on i and k is the form of the equilibrium solution to equations (7), (8) and (9). It is clear that The solution is that the rotational axis motion is the intersection of the unit sphere and the parabolic cylinder. It is stably derived from the first integral expression of equation (6) above, which shows that equilibrium Because of the solution, this intersection is a single point. This closed contour property is defined by this set of equations represents the stability of the equilibrium motion shown by .

To illustrate this concept, a 500 kilometer orbit tilted at an angle of 28.5° Think of a large space station placed on a planet. Because of such a trajectory, the node inverse The line speed is 6.72@ per day, with an orbital period of 94.13 minutes. The spaceship is It has double rotating device structure including large rotor, gyroscope solidity and It is rotated to provide both a rotating gravity environment, and a despanning zero gravity section.

Figure 5 shows spacecraft inertia ranging from 1.2 to 1.8 at rotational speeds of 1 to 6 revolutions per minute. The critical angle φ0 is shown for the value of the rate σ. Because of the double rotation application, σ is the spacecraft's lateral habitus. is the ratio of rotor rotational inertia to rotational inertia. A small value of φ0 is due to the power effect. High rotational speeds and low σ values are desired and preferred for this application. Because of this, the spaceship Designers must reduce the rotor mass to produce a satisfactory rotational axis angle φ0 for such a goal. Determine characteristics and rotation speed.

The method of the invention is compatible with both rotating and dual rotating spacecraft. In the latter case, only However, the spacecraft rotational inertia is determined by the rotor in determining the rotational axis angle φ0. must be replaced by rotational inertia.

Four orientation angles φ for each orbit and spacecraft. The equation ( This is shown from the equilibrium states of 7), (8) and (9). In general, the smallest φO value is of most interest for power research. However, other angular solutions maintain the rotation axis can be used to do the same.

Therefore, the orbital inclination, orbital velocity and retrograde velocity of the orbital line of a node are defined as its orbital parameters. A method for passively maintaining the attitude of a rotating orbital body having as a data is described, Therefore, the direction angle of the body's rotation axis is the same as when the body's orbit is precessing. In order to provide optimal antenna gain and optimal solar irradiation, the body has a flat orbit. It remains essentially fixed and stable with respect to the plane. to orient the satellite By using the method of the present invention for passive stabilization of in weight, complexity, and energy consumption present in active stabilization systems of Disadvantages were minimized.

In order to show how the present invention can be effectively used, the attitude of a rotating body on an orbit according to the present invention is described below. Although the specific apparatus of the method for controlling the It is clear that this is not the case. Therefore, it is possible for a person skilled in the art to and all modifications, changes or equivalent devices as defined in the appended claims. It should be considered that the invention falls within the technical scope of the present invention as described above.

1) Momentum Tribunal Report Cow

Claims (6)

[Claims] (1) Orbital parameters: orbital inclination i, orbital velocity Ωo, and orbit line of node γ Therefore, the rotational axis direction angle φo of the body is such that the trajectory of the body is essentially fixed and stabilized with respect to the body's orbital plane even when in motion How to passively stabilize the attitude of a body in rotating Earth orbit such that In, before defined by the ratio of the rotational inertia of said body to the lateral inertia of said body Select the mass shape σ for the body, and select the rotational axis direction angle φ for the body. Choose the rotational speed Ω such that o is an equilibrium solution to the following relation, φo=ar c yan (zo/yo) + i-π/2 In the formula, the orbit standard axis is the xyz orbital coordinate system. with z along and x at the ascending node, Xo=0 yo=(zosini)/(cosi-kz)i=orbit inclination k=1.5 ((σ-1)/σ) (Ωo2/Ω■) and zo is the following wattage k2zo4−2kcosizo3 +(1-k2)zo2+2kcosizo-cos2i=0 initially orienting the body on the orbit by the rotational axis direction angle; Law. (2) The axis of rotation of the body is determined by the polar axis of the earth and the normal to the orbital surface of the body. 2. The method of claim 1, wherein the method is placed in a flat plane. (3) The axis of rotation of the body is oriented between the north pole and the normal to the orbit. Method. (4) Passively stabilize the posture of a rotating body in orbit of the Earth that is undergoing precession In the method, if the trajectory of the body also precesses, Even if the body is essentially fixed and stable with respect to the raceway of the body, maintain the rotational axis direction of the orbital inclination such that the precessions of said body and said orbit are equal and directionally opposite; , the body mass shape and orbital parameters, including the orbital velocity and the retrograde velocity of the orbital line of the node. the plane defined by the Earth's polar axis and the body's orbit normal. and positioning the rotation axis of the body between the polar axis and the orbit normal, The gravitational gradient precession of the rotational axis produces an axial equilibrium form, so it is a retrograde movement of the orbital normal. A method involving selecting the rotation axis angles to be equal. (5) A claim including a step of initially orienting the body on the orbit at the rotation axis angle. The method described in 4. (6) In an earth orbit system in which a rotating artificial satellite is placed in the earth's orbit. hand, A rotating orbital body is determined by the ratio of the rotational inertia of the body to the lateral inertia of the body. with a selected rotational speed that matches the desired orbital parameters. satisfies the following definition, i = orbital inclination k=1.5((σ-1)/σ)(Ωo2/Ω■) In the formula, σ = (rotational inertia of spacecraft) / (lateral inertia of spacecraft) Ωo = orbital velocity Ω=rotation speed γ = retrograde velocity of the node's orbit line Then, the axis of rotation of the orbital body is the angle φo defined below, and φo=arc t an(zo/yo)+i-π/2 In the formula, because of the xyz orbital coordinate system, along the orbital normal axis has z at the ascending node, holds the following relational expression, and xo=0 yo=(zosini)/(cosi-kz) and zo is the next watch. nine k2zo4-2kcosizo3 +(1-k2)zo2+2kcosizo-cos2i=0 A method involving being a solution to .