JPH0431920B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention suppresses the disturbance torque caused by the wheels that acts when transitioning from a control mode that uses wheels as actuators to a control mode that uses actuators other than wheels such as thrusters. The present invention relates to an attitude control device for an artificial satellite whose purpose is to

[Prior art]

Figure 1 shows a block diagram of a conventional wheel-based attitude control system for an artificial satellite. In the figure, 1 is an attitude sensor, 2 is an attitude control law calculation unit, and 3
is the wheel speed loop and wheel drive circuit, 4
5 is a wheel, 5 is a sensor signal that is the output of the attitude sensor 1, 6 is a compensation element input signal, 7 is a sensor signal on/off switch for controlling the compensation element input signal 6 by turning on/off the sensor signal 5, 8 teeth
Integral element represented by K _I /S, 9 a proportional gain element represented by K _P , 10 a differential element represented by K _D S/(1+T _D S), 11 an integral element output signal,
12 is a proportional gain element output signal, 13 is a differential element output signal, 14 is a wheel speed command signal, 1
5 is an adder which adds the output signals 11, 12, 13 to produce the wheel speed command signal 14;
6 is an integral element output reset section for setting the output of the integral element 8 to zero, 17 is a wheel tachometer signal representing the speed of the wheel 4, and 18 is a wheel drive signal output from the wheel speed loop and wheel drive circuit 3. .

Here, "S" indicates the Laplace operator.

Wheel speed loop and wheel drive circuit 3
Since the wheel speed command signal 14 generates the wheel drive signal 18 so as to match the wheel tachometer signal 17, the speed of the wheel 4 is controlled to follow the wheel speed command signal 14. For this reason, the attitude control law calculation unit 2 receives the sensor signal 5 which is the output of the attitude sensor 1 as input, and generates an appropriate wheel speed command signal 1 using the integral element 8, the proportional gain element 9, the differential element 10, etc.
4, the attitude of the satellite will be controlled stably. If the wheel 4 has a bias speed and is used around that bias speed, the above bias is added in the wheel speed loop and wheel drive circuit 3, and the wheel speed command signal 14 is calculated based on the change from the bias speed. shall represent minutes.

Now, let us consider a case where the control mode using the attitude control system using wheels as described above is shifted to a control mode in which the attitude is controlled using an actuator other than the wheels during orbit control or the like.

In this case, wheel control can be carried out by maintaining the wheel speed at the time of transition to the control mode or returning it to the nominal speed, but usually from the viewpoint of initial conditions etc. when returning to the control mode using wheels. In many cases, a method is adopted in which the speed is returned to the nominal speed.

In the conventional attitude control device shown in FIG. 1, when transitioning to the control mode as described above, the sensor on/off switch 7 is turned off, the compensation element input signal 6 is set to zero, and at the same time, the integral element output reset section 16 is driven. The output signal 11 of the integral element 8 is set to zero. This operation causes the wheel speed command signal 14 to become
It suddenly changes from a certain finite value that depends on the state of the attitude control system before switching to the control mode to zero.

The wheel speed loop and wheel drive circuit 3 will therefore accelerate or decelerate the wheel 4 with maximum torque. In this case, for an attitude control system that uses an actuator other than the wheel, the acceleration/deceleration torque of the wheel acts as a disturbance torque and disturbs the attitude of the satellite. For this reason, the conventional device as described herein has the drawback of generating a large attitude error when transitioning to the control mode.

[Summary of the invention]

This invention has been made to eliminate such drawbacks, and includes an integral element output low speed zero transition control section, which gradually returns the wheel speed command signal to zero, thereby controlling the control mode when transitioning to the control mode. The present invention provides an attitude control device for an artificial satellite that suppresses disturbance torque caused by wheels.

[Embodiments of the invention]

FIG. 2 is a block diagram showing an embodiment of the present invention, and in the figure, numerals 1 to 18 are the same as the conventional control device described above. 19 is an integral element output low speed zero shift control section for gradually shifting the output signal 11 of the integral element 8 to zero; 20 is a feedback gain section; 21 is a speed change rate limiter; 22
is integral element output zero transition on/off switch, 2
3 is an integral element input signal adder. The integral element output low speed zero transition control section 19 is connected to the above-mentioned 20 to 23.
When transitioning from a mode in which the attitude is controlled by wheels to a mode in which the attitude is controlled by actuators other than wheels, such as during orbit control, the sensor signal on/off switch 7 is turned off, and the integral element zero transition is turned on. By turning on the /off switch 22, the integral element output signal 11 gradually shifts to zero. The speed change rate limiter 21 determines the speed change rate, and by appropriately setting the value of this limiter, the maximum value of the disturbance torque due to the wheel can be suppressed to a target value or less.

Note that the actual wheel speed command signal 14 is:
It is the sum of the integral element output signal 11, the proportional gain element output signal 12, and the differential element output signal 13, but when the attitude control system using wheels reaches steady state, the compensation element input signal 6 becomes almost zero. Therefore, the output signals 12 and 13 hardly change depending on whether the sensor signal on/off switch 7 is turned on or off. Therefore, when looking at the change in the wheel speed command signal 14 at the time of transition to the control mode, it is practically necessary to focus only on the change in the output signal 11 of the integral element 8.

When using this wheel control system for normal attitude control, the integral element output can be reduced by turning off the integral element output zero transition on/off switch 22 and turning on the sensor signal on/off switch 7 at the same time. The feedback loop of the speed zero transition control section 19 is terminated, and the integral element 8 comes to work as a normal integral element. Although the integral element output reset section 16 is not essential to the present invention, it may be used when changing control modes where control accuracy is not required.

By the way, in the above explanation, the attitude control system around one axis was described as an example, but the present invention can also be applied to the attitude control system around three axes by providing three control systems similar to the one explained in FIG. 2. Needless to say, it is applicable.

〔Effect of the invention〕

As described above, the present invention has the effect that by adding the integral element output low speed zero transition control section, the disturbance torque caused by the wheels at the time of transition to the control mode is reduced, and the attitude error can be suppressed to a small level.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating a conventional attitude control system using wheels of an artificial satellite, and FIG. 2 is a diagram illustrating an embodiment of the present invention. In the figure, 1 is an attitude sensor, 2 is an attitude control law calculation unit, 3 is a wheel speed loop and wheel drive circuit, 4 is a wheel, 5 is a sensor signal, 6 is a compensation element input signal, 7 is a sensor signal on/off switch, 8 is an integral element, 9 is a proportional gain element, 10 is a differential element, 11 is an integral element output signal, 12 is a proportional gain element output signal, 13 is a differential element output signal,
14 is a wheel speed command signal, 15 is an adder, 16 is an integral element output reset section, 17 is a wheel tachometer signal, 18 is a wheel drive signal,
19 is an integral element output low speed zero transition control section; 20
21 is a speed change rate limiter, 22 is an integral element output zero shift on/off switch, and 23 is an integral element input signal adder. It should be noted that the same or corresponding parts in the drawings are designated by the same reference numerals.

Claims (1)

[Scope of Claims] 1. An attitude sensor, a sensor signal on/off switch provided at the output end of the attitude sensor, an integral element, a proportional gain element, and a differential element to which the output signal of the attitude sensor is respectively input by the switch; an attitude control law calculation section having an adder that adds the output signals of the integral element, the proportional gain element, and the differential element and outputs a wheel speed command signal; and a wheel speed is generated from the attitude control law calculation section. In an attitude control system for an artificial satellite equipped with a wheel speed loop and a wheel drive circuit for following a wheel speed command signal, the attitude is controlled from a mode in which the attitude is controlled by the wheels to an actuator other than the wheels during orbit control, etc. An attitude control device for an artificial satellite, comprising: an integral element output low speed zero transition control unit that gradually transitions the output of the integral element of the attitude control law calculation unit to zero when transitioning to a control mode. 2. A feedback gain section that inputs the output of the integral element, a speed change rate limiter that inputs the output of this feedback gain section, and an integral element output zero transition ON connected to the output end of this speed change rate limiter. Claim 1, characterized in that an integral element output low speed zero shift control section is constituted by a /off switch and an adder for applying the output of the limiter to the integral element via the switch.
Attitude control device for an artificial satellite as described in . 3. The artificial intelligence according to claim 1 or 2, characterized in that the sensor signal on/off switch is turned off at the time of transition to the control mode, and the integral element output zero shift on/off switch is turned on. Satellite attitude control device.