FI91198B - Method for mechanical stabilization - Google Patents

Description

91198

Method for mechanical stabilization

The invention relates to a method according to the preamble of claim 1 for stabilizing a mechanical body 5 independently of the movements of the support base. Using the method according to the invention, the body remains and is able to be held in the desired position with respect to the ground's gravitational field, even if the support base supporting the body tilts and / or moves in different directions. One application 10 in which the application of the method is very necessary is a satellite dish of a ship.

In practice, mechanical stabilization is now most often carried out in such a way that the moments of inertia caused by the body on its support base 15 and the movements of the support base are compensated by various active actuators so that the body remains in the desired position. The current position of the body is measured in relation to the gravitational field of the ground and the deviation from the desired position is corrected by controlling the actuators to eliminate the deviation.

The problem with this method is the limited stabilization rate that can be achieved. As the accelerations and the movement speeds of the support base exceed the maximum response speed of the actuator and the equipment controlling it, the body deviates from the desired position. In addition, the high cost of actuators and measuring sensors limits the range of application for stabilization.

30 Another method of stabilization currently in use is based on the use of a vortex force to maintain the position of the axis of rotation of the flywheel. The piece is then supported above its center of gravity, whereby the gravity of the ground tends to pull the piece to the desired position.

35 The problem with this method is the change in position caused by large lateral accelerations and the rotation of the vortex axis caused by the accelerations applied to the vortex.

The object of the present invention is to eliminate the above-mentioned drawbacks as much as possible and thus to increase the state of the art in the art. To achieve this object, the method 5 according to the invention is mainly characterized in that - the body is supported substantially at its center of gravity so that the moments of inertia caused by the attachments to the body are canceled, and 10 - to maintain the position of the body with respect to the gravitational field of the body. to remove the movement space of the body and / or the support frame, and that 15 - on the basis of the measurement results, maintain the position of the body with forces acting on a substantially non-contact principle, generated, if necessary, on the basis of the measurement results.

Thus, the method according to the invention is based, firstly, on the fact that the functional body to be stabilized, such as a satellite antenna, is supported with low friction from its center of gravity or close to its center of gravity. In practice, this is often not possible, especially in satellite antenna applications, so the focus can be shifted to the point required by the application of the method and in particular the functions of the functional body by attaching at least one counterweight to the functional body. Em. the whole body can then be supported 30 on a support frame associated with the support base, by means of which the center of gravity of the whole body is raised from the surface of the support base. When the whole body is thus supported, the moments of inertia caused by the accelerations in all directions in the total body are canceled out. Thus, in this context, a total body 35 means a combination of a functional body, such as a satellite dish, the orientation of which must be maintained with an accuracy of less than 3 91198 degrees in the satellite direction despite the movements of the support base, and one or more counterweights structurally required. 5 to achieve functions.

Furthermore, the method according to the invention is based on the fact that although the body is supported with low friction from or close to the center of gravity, forces due to friction, Coriolis force and the like are generated, which tend to change the position of the body, i.e. the method corrects creep. This is done by applying the forces provided by the non-contact principle.

This is particularly advantageous because, after the effect of the forces tending to change the position of the body has been eliminated, in particular by correcting the position of the body, e.g. the body is no longer subjected to support reactions caused by the above-mentioned actuators used for repair, which would affect the position of the body, e.g. with the support reaction forces between the body and the support base. The non-contact principle, which eliminates the effect of forces tending to change the position of a body or corrects minor changes in position due to body creep, can be applied by fluidized motion, force due to electric magnetic field change, relative position and / or kinetic energy, with a rotating member connected to it, such as a flywheel. At least the above-mentioned forces, applied on a non-contact principle, if necessary, do not cause support reaction forces between the body and the support frame when the it is not necessary to use the forces to change the position of the part e.g.

to eliminate the effect of friction (forces caused by the support bearing of the fulcrum) and the Coriolis force.

4

By fluidized medium in particular is meant in this context liquids, gases and / or particles which have been brought into motion by means of at least one actuator connected to the body, in which said correction of the position of the body is effected by forces caused by changes in the motion of the fluidized medium. In this case, the body is subjected to the reaction force and / or the impact force caused by the motion space of the fluidized medium. One particularly preferred medium is air.

The method according to the invention thus enables the so-called the use of a slow control system, which makes the stabilizing equipment implementing the method considerably cheaper to manufacture than current systems based on the use of different types of active actuators. The slow control system corrects the creep in the position of the part by controlling the operation of the actuators so that a position correction is achieved. 20 In this context, a slow control system means a system whose response speed is at least a decade lower than the maximum speed of movement of the support frame. That is, if, for example, the hull of a ship oscillates around its longitudinal axis (engl. Max) max. 2e / s the response speed of such a slow control system is less than or equal to 0,2 ° / s.

The appended dependent claims further disclose some preferred embodiments of the method according to the invention.

In the following description, the method according to the invention is illustrated in more detail by reference to the application examples shown in the accompanying drawings. In the drawings li.

5 91198 Fig. 1 shows an application of a method according to the invention for stabilizing a satellite receiving antenna on a ship in a schematic side view, Fig. 2 schematically shows different operating modes of a ship, especially in the satellite receiving antenna placement-10 according to Fig. 1, for determining the forces applied to a satellite receiving antenna Fig. 4 is a block diagram of a control system for actuators operating on the principle of a satellite-15 receiving antenna, Fig. 4 shows an example of a fan arrangement in connection with the counterbalance of the satellite antenna 20 of Fig. 1 generating a fluidized medium, in this case without a change of motion to eliminate the effect of the forces acting, the figure 5 shows the use of the position m of the part in favor of the electric magnetic field. Fig. 6 shows the utilization of kinetic energy by means of a flywheel arrangement 35 to remove the effect of the forces tending to change the position of the body by means of a flywheel arrangement, and Fig. 6 shows another embodiment which is modified. from the representation in Figure 1.

Figure 1 schematically shows an antenna arrangement 1, in particular a TV satellite receiving antenna, to be installed on a ship 5 serving as a support frame. A rotating mechanism 2 is connected to it for turning and tilting the antenna arrangement 1. Furthermore, a counterweight 7 is connected to the antenna arrangement 1 so that the center of gravity of the whole body does not change as a result of the rotation or tilt required by the operation of the antenna arrangement 1. A counterweight 3 is rigidly attached to the stabilizable functional body consisting of parts 1, 2 and 7. The whole body 1, 2, 7, 3 thus formed is supported by a low-friction support 4 from its center of gravity to a support frame 5a attached to the deck of the ship 5 so that the center of gravity and support point above the deck of the ship 5 so that the counterweight 3 is detached from the deck of the ship 5 at its lower part. The support is made in such a way that the functional body, i.e. in particular the antenna arrangement 1, maintains its orientation with the horizontal bow direction of the ship 5. Otherwise, the support 25 allows the body to rotate freely relative to the support frame 5a and thus to the support frame, i.e. the ship 5.

Creep due to friction, Coriolis force or other reasons, such as the moment of inertia due to the change in position of the functional body 1, 2 and 7 with respect to the whole body, is corrected by actuators 6 connected to the slow control system (Fig. 3), i.e. in this application (Fig. 1) 3 in particular to its lower part as shown in FIG.

91198 7

The complete piece 1, 2, 7, 3 and its support frame 5a are mounted on a wind shield belonging to and / or attached to the support frame, i.e. a so-called inside radom 8 to eliminate the effects of wind loads. The arrangement of the above-mentioned entity, i.e. the arrangement according to Fig. 1, on the ship 5 is shown in Fig. 2 with reference p2, whereby Fig. 2 also explains the forces 10 acting on the overall body 1, 2, 7, 3 due to the movement of the ship 5.

As is known, the ship 5 is simultaneously in many different modes of motion. The ship swings in the transverse direction at a certain characteristic frequency f ^. This motion causes transverse-15 accelerations that are repeated at the above-mentioned eigenfrequency.

The ship also swings longitudinally at the characteristic frequency f2. This movement causes repetitive accelerations at frequency f2.

As the ship turns stationary around the point p1 at an angular velocity Wi, at the location of the antenna 1 at the point p2, a centrifugal acceleration w12r1 with a distance between the points p1 and p2 occurs.

25 When a ship 5 is traveling at a constant speed on a curved line, the instantaneous normal acceleration with respect to the line is w2v, where w2 is the angular speed of the ship and v is the speed of the ship.

30 When the speed of ship 5 changes, the acceleration / deceleration ay is obtained, which is parallel to the direction of travel of the ship.

The block diagram of the control system is shown in Figure 3. The position of the body to be stabilized (in this case the whole body 1, 2, 7, 3 in connection with the ship 35 5) is measured with respect to two horizontal different axes. The measurement takes place with two inclinometers 8, 9, which measure the instantaneous total acceleration 8 with respect to its measuring axis. The measuring signals Xi and y] _ are obtained from the inclinometer acting as sensors. The ship's gyrocompass 10 provides the ship's bow direction information h. The ship's log sensor or 5 positioning device 11 (e.g. GPS) provides the ship's speed.

The measurement signal along the transverse axis of the ship 5 is x ^ (inclinometer 8). If the antenna is not on the longitudinal axis of the ship 10 5, the signal is corrected for errors caused by accelerations due to changes in the bow direction by summing (member 14) the second power 12 of the angular velocity information w derived from the direction information h multiplied by the transverse component of distance rx (Fig. 15 2).

The new signal, X2, is corrected for lateral accelerations due to changes in the ship's trajectory by summing (member 15) the ship's forward angular velocity w multiplied by the ship's velocity v. multiple times, minimizing the effect of this swing on the measurement result. The length 25 of the period is obtained, for example, from the measurement signal of an acceleration sensor (member 18) measuring transverse acceleration or is set constant on the basis of the characteristics of the ship. The low-pass filtered signal X4 is fed to a controller 19 which controls at least one actuator 20 20 operating in the X direction (Figures 4-6).

The measurement signal along the bow axis of the ship is y ^ (inclinometer 9). If the antenna is not on the transverse axis of the ship, the errors caused by the accelerations due to changes in the bow direction 35 of the ship are corrected from the signal y ^ by summing (member 21) the angular velocity information w 91198 9 derived from the direction information h by the second power multiplied by the distance r1 (Fig. 2) The corrected signal y2 is corrected (member 23) for errors caused by accelerations 5 due to changes in the speed of the ship by summing the acceleration information ay (member 24) derived from the speed information v.

The signal y3 thus obtained is low-pass filtered (member 25) with a long time constant set to a multiple of the period-10 length of the frequency f2 of the longitudinal rocking motion of the vessel, whereby the effect of this rocking on the measurement result is minimized. The length of the period is obtained, for example, from the measurement signal of an acceleration sensor measuring the longitudinal acceleration (member 26) or is set constant on the basis of the characteristics of the vessel.

The low-pass filtered signal y4 is fed to a controller 27 which controls at least one actuator 28 operating in the Y direction (Figures 4-6).

As actuators 20, 28, for example, four fans 20a, 20b of device-20 are used; 28a, 28b (two in both directions X and Y), which are mounted according to Fig. 4 in connection with the counterweight 3 at its lower part. The control system explained in connection with Figure 3 controls the fans 20a, 20b; 28a, 28b so that the repair movement is started by controlling the fans for a certain time, at which time the repair movement begins. When the desired position is approached, the fans are guided in the opposite direction for a certain time until the corrective movement stops. The ratio of these acceleration and deceleration times is adjusted according to the D-term 30 of the PD controller, i.e. the movement of the part is stopped and the time between the acceleration and deceleration according to the P-term (not shown to the person as obvious). The control system takes into account the low-pass filtering of the measurement signal by setting the dead time. The fans 35 thus produce forces acting on the body 1, 2, 7, 3 on the basis of reaction and / or collision principles.

10

The measurement signals X4 and Y4 obtained from the control system described above, in particular from its measuring system, give the position information of the whole body corrected for the lateral accelerations. The control system can be implemented with analog elements, using digital signal processing with a microprocessor or a combination thereof. Component selection is within the skill of the art, so it will not be explained in more detail in this context.

It can be seen in Figure 4 that the fans 20a, 20b act as actuators 6; 28a, 28b are arranged as the outer wall lie of the counterweight 3 so that both pairs 15 are on the same line or in the direction X or Y with respect to the direction of movement of the air flowing through the fans. The directions X and Y are arranged perpendicular to each other in the embodiment of Fig. 4 as well as in Figs. 5 and 6. It is clear that other angles between the 20 directions may also be considered and are mandatory if there are more than two directions. The fans are housed in a kind of frame 29, the central opening 30 of which acts as an air flow path through the fans either towards the radom 8 25 and / or from the direction of the radome 8 towards the opening 30 and out of the counterweight 3 connection (see arrow 31, fan 20a).

It will be apparent to one skilled in the art that only two fans can be used, one in each of the X and Y directions. It will further be appreciated that the direction of flow of the fluidized medium through the fans may be reversed.

Fig. 5 shows an embodiment of the invention in which a principle analogous to Fig. 4 is applied, applying the forces caused by the change in the state of motion of the fluidized medium (air, etc.).

II

91198 instead of 11 actuators 6 electromagnetic pairs (four) 32a, 32b; 33a, 33b in the X and Y directions (in pairs acting in both directions X and Y). Elinparien 32a, 32b; 33a, 33b 5 each member consists (e.g. a pair of members 32a, direction X in Fig. 5) of a permanent magnet 34 (first member) and, in cooperation with it, an electromagnet 35 (second member) arranged to provide a non-contact force. It is particularly advantageous from the point of view of simple control of the electronic messages coming from the control system (Fig. 3) that the electromagnets 35 are fixedly connected to the support frame 5a and / or the radome 8 and the permanent magnets 34 at a corresponding position in the counterweight 3.

15

It will be apparent to one skilled in the art that only one pair of members 34, 35 may be acting in the X and Y directions.

The pairs of members can be arranged in the lower part of the counterweight 3 as shown in Fig. 4.

20

Figure 6 is a perspective view of an application of the invention based on the utilization of kinetic energy.

It consists of two pairs (analogously according to Figures 4 and 5) of flywheels 25 36a, 36b acting as actuators 6; 37a, 37b, whose changes in relative position and / or kinetic energy (rotational speed) provide the desired change in the position of the body.

In the embodiment shown in Fig. 7, the Radom 8 is arranged in connection with an intermediate plane 5b belonging to the raised support frame 5a. In this case, the counterweight 3 communicates freely with the outside air between the deck of the ship 5 and the intermediate plane 5b. In this case, e.g. the application according to Fig. 4 can be modified so that, for example, water which is removed along the deck of the ship 5 can be used as the fluidizing agent 35.

12

It is clear from the above that the invention is very complex, including for the person skilled in the art several applications within the basic idea of the invention. In particular, it should be noted that although the invention has been illustrated in the above description by means of a satellite antenna application, the method can be applied in all applications where stabilization of the mechanical body is necessary. The forces provided by the non-contact principle can also be used to change the position of the part with respect to the support frame and further in question. after the change to maintain the position in accordance with the basic idea of the invention.

li

Claims (10)

Method for stabilizing the position at a piece (1, 2, 7, 3) supported xnot a relative field of attraction with respect to the support frame (5) of the earth, characterized in that the piece (1, 2, 7, 3) is substantially supported. at its center of gravity, say that the moment of inertia caused by the accelerations directed to the pieces is thrown, that in order to maintain the position of the piece (1, 2, 7, 3) relative to the field of attraction and to eliminate the influence of forces which tend to change the position , in particular friction, the movement of the piece (1, 2, 7, 3) and / or the supporting body (5) is measured, and that - on the basis of the measurement results, the position of the piece (1, 2, 7, 3) is maintained with forces that work substantially on the contact-free principle and if necessary based on the measurement results. Method according to claim 1, characterized in that said substantially contactless force is achieved by bringing a fluidizable medium, such as a gas, liquid and / or particles into a movable position. 3. A method according to claim 1, characterized in that said substantially contactless force is produced by an electric magnetic field. 4. A method according to claim 1, characterized in that said substantially contactless force is effected by a change in the relative position and / or the movement energy of a member (1, 2, 7, 3) placed in connection with the piece (1, 2, 7, 3). 36a, 26b; 27a, 37b). 91198 17 5. A method according to claim 2, characterized in that said substantially contactless force is applied to the reaction and / or collision principle, whereby two or more blasts or corresponding means are placed in connection with pieces (1, 2, 7, 3). , whereby directions of action (X, Y) in at least some of them are deflected from each other. 10 6. A method according to claim 3, characterized in that said substantially contactless force is effected by two or more pairs of members operating on the electromagnetic principle, of which the first member (34) is placed in connection with the piece (1,2). 7, 3) and the second member (35) are placed in connection with the support body (5) or a member (5a) attached thereto, and that the directions of action (X, Y) of at least some pairs of organs are deflected from the direction of action of another pair of members. 20 7. A method according to claim 4, characterized in that said substantially contactless force is effected by at least two rotating members located in conjunction with the piece (1, 2, 7, 3), such as balance wheels, wherein the directions of action (X, Y) of at least some of them are disconnected from each other. 8. A method according to claim 1, characterized in that the piece (1, 2, 7, 3) is constituted as a whole piece having a functional support body (5) for functional piece (1, 2, 7), as a satellite antenna and at least one counterweight (3) attached to the functional piece or the like, that the whole piece is supported (4) against a support frame (5a) fixed in connection with the support body (5a), substantially to the unit piece (1, 2, 7, 3). ) center of gravity, that the functional piece (1, 2, 7) is at least provided with a means (7) for holding the center of gravity of the functional piece (1, 2, 7) in its 18 position as it moves relative to the counterweight (3) or such as to incline the center of gravity of the whole piece (1, 2, 7, 3) at the support point (4) and that means (6) for providing the contact-free force are placed at least partially in connection with the counterweight (3) or the like. Method according to claim 1, characterized in that 10. in connection with the piece (1, 2, 7, 3) and / or the support body (5), one or more measuring sensors (8, 9, 10, 11) are placed so that measured from the stop of movement of the piece (1, 2, 7, 3) and / or the support body (5), that a motion stop corresponding to the measurement signal (x ^, y1 (h, v)) is transmitted to the control system and at least one control signal proportional to the movement end (x4, y4) constitute, and that with the control signal, the function of the at least partially connected with the drive (1, 2, 7, 20) is regulated, the control system being a so-called delayed control system whose operating speed is at least a decade less than the maximum operating speed corresponding to the corresponding movement end of the support body (5) Method according to claim 1, characterized in that the position of the piece (1, 2, 7) is changed with said substantially contactless force.