DE3214378C2 - Device for the flywheel control of a satellite - Google Patents

Abstract

A satellite equipped with one or more spin wheels (17) is to be improved with regard to the regulation of the spin wheel (17) in such a way that inevitable spin losses are compensated. For this purpose, a computationally determined ideal swirl wheel (16) realized on the basis of a model is constantly compared with the real swirl wheel (17), the real swirl wheel (17) tracking the ideal swirl wheel (16).

Description

The invention relates to a device for controlling one or more flywheels Flywheels equipped satellites according to the preamble of the claim.

It is known to use flywheels to control satellites stabilize or regulate their position. In the F i g. 1 and 2 show the flywheel control of a satellite according to the prior art

An attitude angle 1 of the satellite is measured by an attitude angle sensor 2, from which a sensor signal 3 is generated Input signal a position error signal 6, which is the difference between a position angle command signal 5 and the sensor signal 3 and generates a torque control signal 8 as an output signal therefrom. The torque control signal 8 is fed to a flywheel 7, which generates a torque 9 with which the regulation of the satellite 10 is carried out in the desired position.

Due to the satellite dynamics, the position of the satellite 10 is influenced in accordance with the torque 9. The satellite 10 is in its position in this way regulated with a closed control loop

F i g. 2 relates to the torque control signal 8 for the flywheel 7 of the satellite. A motor with feedback is switched by a motor control circuit 11 to generate a torque 12 proportional to the torque control signal 8. In the example, the motor control loop 11 has the transfer function KJ {\ + T _n S). Although the torque 12 of the motor is proportional to the torque control signal 8, a torque loss 13 (e.g. caused by bearing friction, speed fluctuations, temperature changes, etc.) results in a smaller torque than intended.

As a result, the speed 15 of the flywheel is lower than expected because of its dynamics represented by the function block 14, with the result that the accuracy of the position control deteriorates. The wheel dynamics 14 has a transfer function M (Iw ■ s), where I _{w is} the moment of inertia of the flywheel.

In order to compensate for such a torque deviation, a lead is made according to the prior art corresponding to the torque loss 13 to the Torque control signal! 8 added This lead is kept constant. However, since the torque loss 13 is subject to changes e.g. B. as a result of Such a constant lead leads to changes in the speed of the flywheel or temperature fluctuations to an increasing difference between the torque which corresponds to the torque control signal and the torque 9 actually exerted by the flywheel.

ίο A facility of the type mentioned above is off the US-PS 39 68 352 known According to Fig. 3 there, a computer generates a torque control signal Tc which is a quasi-ideal Flywheel is supplied in the form of an integrator, which emits a target angular velocity signal From this and a supplied actual angular velocity signal, an angular velocity error signal is formed which is supplied to a motor for generating torque. That differing from this The given torque T _M is finally caused by a disturbance ^{torque U 1} Sn ^ ef ° wrfgisr * hf er »HaR a speed of the real flywheel deviating from the desired speed speed signal and formation of the angular speed error signal can be remedied. However, this facility can still be improved in terms of its efficiency. The invention is therefore based on the object of a Establish the type mentioned at the beginning which is the difference between the torque represented by the torque control signal and the actual torque can always be kept as small as possible.

This object is achieved according to the invention in that from the angular velocity error signal a feedback signal is generated via a controller, which is added to the torque control signal, and the resulting surf signal the one output signal for controlling the real flywheel is

With the help of this simple device, it is possible to generate the torque that is important for antenna alignment and other position control tasks of the flywheel to the precisely required values. This also creates considerable energy and fuel savings as necessary error corrections are kept to a minimum. An embodiment of the invention is based on the

5J F i g. 3 explained in more detail

An ideal flywheel is represented by the function block and a real flywheel is represented by the function block 17 ideal flywheel is tracked without loss of torque.

The real flywheel 17 corresponds to that shown in FIG. The ideal flywheel 16 includes one ideal motor control circuit 18 and ideal wheel dynamics 19, which simulates the real engine control loop 11 and the wheel dynamics 14 of the real flywheel 17 are. The ideal flywheel 16 has the transfer function

which by means of a computer or analog circuit according to the

Transfer function

K _n , 1

p Under normal conditions, the torque

1 + T _m s I _w s

of the real flywheel 17 is defined.

The ideal flywheel 16 produces a torque which is directly proportional to the torque control applied as an input signal. The real flywheel 17 has a feedback with respect to the torque control signal 8 in such a way that the angular velocity signal 15 of the real flywheel 17 as well as the angular velocity signal 21 of the ideal flywheel 16 is fed to a summing point. A controller 22 detects the angular velocity error signal 23 between the angular velocity signal 21 of the ideal and the angular velocity signal 15 of the real flywheel and from this forms a feedback signal 24. The input signal 25 for the real flywheel 17 is the sum of the torque control signal! S and the feedback signal 24 from controller 22.
p

fö which f by the motor control loop 11 with respect to the rear: l'ührsignal is evidence for the ery Drehmomentkompensierung 24, the same size as the Drehmomentverf ·; iust 13, so that the latter is eliminated, thus the torque}: torque 9 is kept proportional to the torque control signal fs 8. If the torque loss 13 varies, the feedback signal 24 changes accordingly, and the Jj torque loss 13 is eliminated due to the feedback f> of the angular velocity error signal 23
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ti 1 sheet of drawings

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Claims (1)

Claim: Device for the flywheel control of a satellite equipped with one or more flywheels, in which the angular velocity of the real flywheel is constantly monitored by generating an angular velocity error signal that angular velocity is tracked, which results from a replica of the ideal Flywheel results, to which a torque control signal is fed, characterized in that a feedback signal (24) is generated from the angular velocity error signal (23) via a controller (22), which is added to the torque control signal (8), and that as a result resulting sum signal the input signal (25) for the control of the real flywheel (17) is