CN106915476B - A kind of Split type electric magnetic coupling satellite load direction control method - Google Patents

Abstract

The present invention relates to a kind of Split type electric magnetic coupling satellite loads to be directed toward control method, and satellite load and satellite body are not directly contacted with, and ontology micro-vibration is isolated, guarantees the super quiet super steady of load；Posture is carried out using electromagnetic voice coil actuator and is directed toward control, without consuming working medium, can be used for a long time, broadband is big, response quickly, by adjusting the attitude angle of the controllable satellite load of size of current, attitude angle is made to reach desired value.Super quiet requirement is realized, the stability of direction is improved.

Description

A separate electromagnetic force coupling satellite payload pointing control method

technical field

The invention relates to the field of satellite load pointing and control, in particular to the problem of ultra-static pointing control of a separate electromagnetic force coupling satellite load.

Background technique

Satellite payload pointing technology is an important part of satellite and plays a decisive role in some missions. For the ultra-static pointing requirements of satellite payloads, the servo mechanism needs to provide a small amplitude and high precision control torque. In the traditional U-shaped motor servo pointing control, due to the existence of the friction force of the servo motor, the pointing accuracy of the load is limited. At the same time, the servo motor is a disturbance source, which transmits micro-vibration to the satellite load, which cannot achieve the ultra-static requirement and affects the pointing. of stability. The traditional jet mechanism can provide a large pulse torque to control the attitude of the load, but it is easy to cause micro-vibration, it is difficult to carry out high-precision pointing, and the jet actuator consumes working fluid, which is not suitable for long-term work. In order to meet the high-precision, high-stability and ultra-static requirements of satellite payload pointing at the same time, the present invention proposes a method for super-static pointing manipulation design and control of the payload.

Due to the direct contact with the satellite payload, various traditional technologies are easy to cause micro-vibration of the payload, which greatly limits the stability and accuracy of the satellite payload pointing. Therefore, in terms of pointing control, the present invention adopts a separate electromagnetic coupling method, the satellite load and the satellite body are not in direct contact, and the micro-vibration of the body is isolated to ensure the ultra-quiet and ultra-stable load; electromagnetic voice coil actuator is used to carry out Attitude pointing control, no need to consume working medium, can be used for a long time, wide bandwidth, fast response, can achieve high precision and high stability.

SUMMARY OF THE INVENTION

In order to realize the ultra-quiet pointing control of the satellite load, the present invention utilizes several separate electromagnetic voice coil actuators to precisely control the three-degree-of-freedom attitude of the load, which improves the pointing accuracy and stability of the satellite load and realizes the ultra-quiet requirement.

To achieve the above object, the present invention discloses the following technical solutions:

A separate electromagnetic force coupling satellite load pointing control method, comprising the following steps:

S1 fixedly connect the satellite-load connecting body with the satellite body, several separate electromagnetic voice coil actuator magnet parts are fixed on the satellite load, and the coil part is fixedly connected with the satellite-load connecting body; it is installed on the satellite load for measuring the load The actual attitude angle of the star sensor; the lens barrel is installed on the upper part of the satellite payload, which is a common component in the space optical system and plays the role of shading, fixing and supporting the camera lens;

S2 performs dynamic modeling on the satellite body and the satellite load respectively, and obtains the relationship between the attitude angle of the satellite load and the control torque of the satellite body on the satellite load;

The S3 coil is energized, and by controlling the size of the current, the separate electromagnetic voice coil actuator generates an output force, and the synthetic control torque is used to control the attitude angle movement;

S4 designs a control method according to the working principle of the separate electromagnetic voice coil actuator and its dynamic model, and obtains a block diagram of the control algorithm of the system, so as to realize the ultra-quiet pointing control of the satellite load;

S5 uses the star sensor to measure the attitude angle, compares it with the desired attitude angle reference value, and uses the difference between the reference angular position and the actual angular position as the control input for compensation. When the actual attitude angle reaches the desired attitude angle, the control is completed.

Further, in the step S1, a total of eight separate electromagnetic voice coil actuators are used, of which four electromagnetic voice coil actuators are symmetrically distributed at the four corners of the load bottom along the satellite load axis, and the other four actuates. The device is installed at an angle of 90° along the load axis at the middle position on the side of the satellite load.

Further, the satellite-load connecting body is a U-shaped structure, and the satellite load and the electromagnetic voice coil actuator are placed on the connecting body.

Further, the magnet part of the separate electromagnetic voice coil actuator is mounted on the satellite load with bolts, the coil part is connected with the satellite-load connecting body with bolts; the lens barrel on the satellite load is connected by bolts.

Further, in the step S2, before the dynamic modeling of the satellite body and the satellite load, the reference coordinate system of the satellite load is first established. For controlling the orientation of the optical axis, the eight actuators are divided into two groups. The four actuators mounted on the bottom control the rotation of the load around the x- and y-axes, and the four actuators mounted on the side control the rotation of the load. Rotation of the z-axis.

Further, in the step S2, when the dynamic modeling of the satellite body is performed, it is regarded as a rigid body, and the reference coordinate system is Ox _r y _r z _r , regardless of the influence of environmental factors, the model is as follows:

in, is the control torque generated by the actuator of the satellite body, is the reaction moment of the load on the satellite body, I _x , I _y , I _z are the inertia moment of the satellite body, ψ, θ, are the yaw, pitch and roll angles of the satellite, respectively, and ω _x , ω _y , and ω _z are the rotational angular velocity of the satellite around the reference coordinate system;

In order to keep the satellite body stable, that is, ω _x , ω _y , ω _z =0, The actuator of the satellite body is used to compensate the influence of the load on the body, and the control law shown in formula (2) is used to stably control the satellite body:

Then the dynamic equation of the satellite body is:

It can be seen from this equation that the three-channel attitude control of the satellite body is completely decoupled, and appropriate differential parameters are selected. and scale parameters The satellite body can be kept stable.

Further, in the step S2, when modeling the satellite load, it is regarded as a rigid body, and its reference coordinate system is Build the model as follows:

in, is the control torque of the satellite body on the load, and is the moment of inertia of the load, ψ _p , θ _p , are the yaw, pitch and roll angles of the load, respectively, is the rotational angular velocity of the load around its reference coordinate system;

Assuming that the satellite payload is a cube, then Then the coupling term in the dynamic equation (4) is eliminated, and the small-angle maneuvering assumption is adopted, assuming , θ _p , ψ _p are all small quantities, ignoring the second-order small terms, so the model is simplified as:

Since the load needs to achieve high-precision pointing, its reference rotational angular velocity is zero, and the reference attitude angle is a constant value, that is, The attitude angle is controlled by the control law shown in formula (6), and the difference between the reference angular position and the actual angular position is used as the input of the control system, so the control torque of the satellite body on the load is:

Then the dynamic equation of the load is:

in, In order to control the differential parameters and proportional parameters of the system, it can be seen from this formula that each channel is decoupled from each other and is a second-order system. According to the selection of parameters k _d and k _p , the motion law of the attitude angle can be determined.

Further, when the control attitude angular movement is compensated, the actual angular position of the satellite load is measured by the star sensor and fed back to the control system to obtain the difference between the reference value and the actual value for compensation; the voice coil model assumes that is known, as shown in formula (8):

F=BIL (8)

Among them, B and L are the inherent properties of the voice coil actuator. As known quantities, I is the current through the coil, which is a control variable. After the coil is energized, an output force is generated. Let the vertical distance between the force and the axis direction be d. , to form a moment along the load axis, which is used to control the deviation of the attitude angle for compensation.

A separate electromagnetic force coupling satellite load pointing control method disclosed in the present invention has the following beneficial effects:

The separate electromagnetic voice coil actuator proposed in the patent of the present invention carries out the pointing control method for the satellite load, and the attitude angle of the satellite load can be controlled by adjusting the current size, so that the attitude angle can reach the desired value. In the present invention, the satellite payload and the satellite body are not in direct contact, so micro-vibration will not be transmitted, the ultra-static requirement is achieved, and the pointing stability is improved.

Description of drawings

Fig. 1 is a flow chart of the method of the present invention;

Fig. 2 Front view of installation of eight electromagnetic voice coil actuators;

Figure 3 is a top view of the installation of eight electromagnetic voice coil actuators;

Figure 4 is a block diagram of the control algorithm, in which, are the proportional and differential parameters of the load, respectively.

in:

1. Lens barrel, 2. Satellite payload, 3. Satellite-load connecting body, 4. Satellite body, 5. Voice coil actuator, 51-coil part, 52-magnet part.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The core of the invention is to provide a separate electromagnetic force coupling satellite load pointing control method, which realizes the ultra-quiet pointing control of the satellite load, uses a number of separate electromagnetic voice coil actuators to perform three-degree-of-freedom attitude precise control of the load, and improves the performance of the satellite load. The pointing accuracy and stability of the satellite payload are achieved, and the ultra-static requirement is achieved.

See Figure 1.

A separate electromagnetic force coupling satellite load pointing control method, comprising the following steps:

S1 fixedly connect the satellite-load connecting body 3 with the satellite body 4, a plurality of separate electromagnetic voice coil actuators 5 and the magnet parts 52 are fixed on the satellite load 2, and the coil part 51 is fixedly connected with the satellite-load connecting body 3; A star sensor for measuring the actual attitude angle of the payload is installed on the payload 2; the lens barrel 1 is installed on the upper part of the satellite payload 2. The lens barrel 1 is a common component in the space optical system, which plays the role of shading, fixing and supporting the camera. the role of the lens;

S2 performs dynamic modeling on the satellite body 4 (excluding the load part) and the satellite load 2 respectively, and obtains the relationship between the attitude angle of the satellite load 2 and the control torque of the satellite body 4 on the satellite load 2;

The S3 coil is energized, and by controlling the magnitude of the current, the separate electromagnetic voice coil actuator 5 generates an output force to synthesize the control torque, which is used to control the attitude angle movement;

S4 designs a control method according to the working principle of the separate electromagnetic voice coil actuator 5 and its dynamic model, obtains a block diagram of the control algorithm of the system, and realizes the ultra-quiet pointing control of the satellite load;

S5 uses the star sensor to measure the attitude angle, compares it with the desired attitude angle reference value, and uses the difference between the reference angular position and the actual angular position as the control input for compensation. When the actual attitude angle reaches the desired attitude angle, the control is completed.

In an embodiment of the present invention, in the step S1, a total of eight separate electromagnetic voice coil actuators 5 are used, of which four electromagnetic voice coil actuators 5 are located at the bottom of the load along the axis of the satellite load 2. The corners are symmetrically distributed, and the other four actuators are installed at an angle of 90° along the load axis at the middle position of the side of the satellite load 2.

In an embodiment of the present invention, the satellite-load connecting body 2 is a U-shaped structure, and the satellite load 2 and the electromagnetic voice coil actuator 5 are placed on the connecting body.

In an embodiment of the present invention, the magnet part 52 of the separate electromagnetic voice coil actuator 5 is mounted on the satellite load 2 with bolts, and the coil part 51 is connected with the satellite-load connecting body 3 by bolts; the satellite load 2 The upper lens barrel 1 is connected by bolts.

During the movement of the satellite, vibration will inevitably occur, which will affect the pointing accuracy of the satellite payload 2. Therefore, it is necessary to control the pointing of the optical axis. In an embodiment of the present invention, before the dynamic modeling of the satellite body 4 and the satellite payload 2 is performed in step S2, the reference coordinate system of the satellite payload 2 is first established For controlling the orientation of the optical axis, the eight actuators are divided into two groups. The four actuators mounted on the bottom control the rotation of the load around the x- and y-axes, and the four actuators mounted on the side control the rotation of the load. Rotation of the z-axis.

In an embodiment of the present invention, when the satellite body 4 is dynamically modeled in step S2, it is regarded as a rigid body, and the reference coordinate system is Ox _r y _r z _r , as shown in FIG. The influence of environmental factors, the model is as follows:

in, is the control torque generated by the actuator of the satellite body, is the reaction moment of the load on the satellite body 2, I _x , I _y , I _z are the inertia moments of the satellite body 4, ψ, θ, are the yaw, pitch and roll angles of the satellite, respectively, and ω _x , ω _y , and ω _z are the rotational angular velocity of the satellite around the reference coordinate system;

In order to keep the satellite body 2 stable, that is, ω _x , ω _y , ω _z =0, The actuator of the satellite body 4 is used to compensate the influence of the load on the body, and the control law shown in formula (2) is used to stably control the satellite body 2:

Then the dynamic equation of the satellite body 4 (excluding the load part) is:

It can be seen from this equation that the three-channel attitude control of the satellite body 4 (excluding the payload part) is completely decoupled, and appropriate differential parameters are selected. and scale parameters The satellite body can be kept stable.

In an embodiment of the present invention, when the satellite payload 2 is modeled in step S2, it is regarded as a rigid body, and its reference coordinate system is As shown in Figure 2, the model is established as follows:

in, is the control torque of the satellite body 4 to the load, and is the moment of inertia of the load, ψ _p , θ _p , are the yaw, pitch and roll angles of the load, respectively, is the rotational angular velocity of the load around its reference coordinate system;

Assuming that the satellite payload 2 is a cube, then Then the coupling term in the dynamic equation (4) is eliminated, and the small-angle maneuvering assumption is adopted, assuming θ _p , ψ _p are both small quantities, ignoring the second-order minor terms, so the model is simplified as:

Since the load needs to achieve high-precision pointing, its reference rotational angular velocity is zero, and the reference attitude angle is a constant value, that is, The attitude angle is controlled by the control law shown in formula (6), and the difference between the reference angular position and the actual angular position is used as the input of the control system, so the control torque of the satellite body on the load is:

Then the dynamic equation of the load is:

in, In order to control the differential parameters and proportional parameters of the system, it can be seen from this formula that each channel is decoupled from each other and is a second-order system. According to the selection of parameters k _d and k _p , the motion law of the attitude angle can be determined.

Since the load is required to have high pointing accuracy, the attitude angle of the load deviates from the reference value under the action of interference. The coil of the voice coil actuator 5 is energized to form a control torque, which is used to adjust the deviation of the attitude angle. In an embodiment of the present invention, when the control attitude angular movement is compensated, the actual angular position of the satellite payload 2 is measured by the star sensor and fed back to the control system to obtain the difference between the reference value and the actual value , to compensate; the voice coil model is assumed to be known, as shown in formula (8):

F=BIL (8)

Among them, B and L are the inherent properties of the voice coil actuator (the magnetic field strength of B, and the total length of L), which are regarded as known quantities, and I is the magnitude of the current passing through the coil, which is the control variable. After the coil is energized, the output force is generated. The vertical distance between the force and the axis direction is d, which forms a moment along the load axis direction, which is used to control the deviation of the attitude angle and compensate.

Parameter setting: This link needs to determine the relationship between the current size and the output force. Using the above linear model, the required parameters such as B, I, and d are measured. The parameters that need to be set are the differential parameters of the three channels in formula (3). and the scale parameters of the three channels and the differential parameters of the three channels in equation (7) and the scaling parameters of the three channels Use the trial and error method to tune these parameters, first adjust the proportional parameter, and then adjust the differential parameter. These two steps are repeated until the performance required by the system is met.

Compared with the content introduced in the background art, the separate electromagnetic voice coil actuator 5 proposed by the present invention carries out a method for directing and controlling the satellite load 2, and the attitude angle of the satellite load 2 can be controlled by adjusting the magnitude of the current, so that the attitude angle reaches the desired value. . In the present invention, the satellite payload 2 and the satellite body 4 are not in direct contact, so micro-vibration is not transmitted, the ultra-quiet requirement is achieved, and the pointing stability is improved.

The above descriptions are only preferred embodiments of the present invention, rather than limitations thereof; it should be noted that although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the above embodiments can still be used for The technical solutions described in the examples are modified, or some or all of the technical features thereof are equivalently replaced; and these modifications and replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (8)

1. A separated electromagnetic force coupling satellite load pointing control method is characterized by comprising the following steps:

s1, the satellite-load connector is fixedly connected with the satellite body, a plurality of separated electromagnetic voice coil actuator magnet parts are fixed on the satellite load, and the coil parts are fixedly connected with the satellite-load connector; a star sensor for measuring the actual attitude angle of the load is arranged on the satellite load; a lens cone is arranged on the upper part of the satellite load and is used for shading, fixing and supporting a camera lens;

s2, respectively carrying out dynamic modeling on the satellite body and the satellite load to obtain the relationship between the attitude angle of the satellite load and the control moment of the satellite body on the satellite load;

s3, electrifying the coil, and controlling the magnitude of current to generate output force by the separated electromagnetic voice coil actuator to synthesize control torque for controlling attitude angle motion;

s4, according to the working principle of the separated electromagnetic voice coil actuator and the dynamic model design control method thereof, a control algorithm block diagram of the system is obtained, and hyperstatic directional control of satellite loads is realized;

s5, the star sensor is used for measuring the attitude angle, the attitude angle is compared with the expected attitude angle reference value, the difference value of the reference angular position and the actual angular position is used as the control input for compensation, and when the actual attitude angle reaches the expected attitude angle, the control is finished.

2. The separated electromagnetic force coupling satellite load direction control method as claimed in claim 1, wherein in step S1, a total of eight separated electromagnetic voice coil actuators are used, wherein four electromagnetic voice coil actuators are symmetrically distributed along the satellite load axis at four corners of the bottom of the load, and the other four actuators are installed at an included angle of 90 ° along the load axis at the middle position of the satellite load side.

3. The separated electromagnetic force coupling satellite load direction control method as claimed in claim 1, wherein the satellite-load connecting body is a U-shaped structure, and the satellite load and the electromagnetic voice coil actuator are disposed on the satellite-load connecting body.

4. The split electromagnetic force coupling satellite load direction control method as claimed in claim 1, wherein the split electromagnetic voice coil actuator magnet part is mounted on the satellite load by bolts, and the coil part is connected with the satellite-load connector by bolts; the lens cone on the satellite load is connected by a bolt.

5. The separated electromagnetic force coupled satellite load direction control method as claimed in claim 2, wherein in step S2, before performing dynamic modeling on the satellite body and the satellite load respectively, a reference coordinate system of the satellite load is first establishedA rotation around the z axle for being directed to the optical axis is controlled, and eight actuators divide into two sets ofly, and four actuator control load of bottom installation are around the rotation of x axle and y axle, and four actuator control load of side-mounting are around the rotation of z axle.

6. The separated electromagnetic force coupled satellite load direction control method as claimed in claim 5, wherein in step S2, the satellite body is considered as a rigid body when being dynamically modeled, and the reference coordinate system Ox is set as_ry_rz_rRegardless of the influence of environmental factors, the model is as follows:

wherein,the control moment generated by the actuating mechanism of the satellite body,is the reaction moment of the load on the satellite body, I_x,I_y,I_zThe moment of inertia of the satellite body, psi, theta,yaw, pitch and roll angles, omega, of the satellite, respectively_x,ω_y,ω_zThe angular velocity of the satellite around the reference coordinate system;

for stabilising the body of the satellite, i.e. omega_x,ω_y,ω_z＝0,ψ,θ,The executing mechanism of the satellite body compensates the influence of the load on the body, and the control law shown in the formula (2) is adopted to stably control the satellite body:

the kinetic equation of the satellite body is:

as can be seen from the equation, the three-channel attitude control of the satellite body is completely decoupled, and proper differential parameters are selectedAnd the ratio parameterThe satellite body can be kept stable.

7. The separated electromagnetic force coupled satellite load direction control method as claimed in claim 6, wherein in step S2, the satellite load is considered as a rigid body when being modeled, and the reference coordinate system thereof is a rigid bodyThe model is established as follows:

wherein,is the control moment of the satellite body to the load, and moment of inertia, psi, of the load_p,θ_p,Respectively yaw, pitch and roll angles of the load,is the angular velocity of rotation of the load about its reference coordinate system;

assuming the satellite load is square, thenThe coupling terms in equation (4) of the dynamics cancel and the small angle maneuver assumption is used, assumingθ_p,ψ_pAll are small quantities, neglecting second order small terms, so its model simplification is:

since the load is pointed with high precision, the reference rotation angular speed is zero and the reference attitude angle is constant, i.e. the load is pointed atThe attitude angle is controlled by adopting a control law shown in formula (6), and the difference value between the reference angular position and the actual angular position is used as the input of a control system, so that the control moment of the satellite body on the load is as follows:

the kinetic equation for the load is then:

wherein,for controlling the differential and proportional parameters of the system, it can be seen from this equation that each channel is decoupled from each other, being a second order system, according to the parameter k_d,k_pThe law of motion of the attitude angle can be determined.

8. The separated electromagnetic force coupled satellite load direction control method as claimed in claim 7, wherein when the control attitude angular motion is compensated, an actual angular position of the satellite load is measured by a star sensor and fed back to the control system, and a difference between a reference value and an actual value is obtained for compensation; the voice coil model is assumed to be known, as shown in equation (8):

F＝BIL (8)

and B, L is the inherent property of the voice coil actuator and is a known quantity, I is the current passing through the coil and is a control variable, after the coil is electrified, an output force is generated, and the perpendicular distance between the force and the axial direction is set as d, so that a moment along the axial direction of the load is formed and is used for controlling the deviation of the attitude angle to compensate.