GB2097966A

GB2097966A - Apparatus for positioning and attitude-stabilising an inert mass pivotably mounted on a movable base

Info

Publication number: GB2097966A
Application number: GB8113165A
Authority: GB
Original assignee: PIETZSCH IBP GmbH; IBP Pietzsch GmbH
Current assignee: PIETZSCH IBP GmbH; IBP Pietzsch GmbH
Priority date: 1981-04-28
Filing date: 1981-04-28
Publication date: 1982-11-10
Also published as: GB2097966B; SE449799C; SE8102532L; SE449799B

Abstract

Apparatus for positioning and attitude stabilising an inert mass 9 pivotably mounted on a movable base includes at least two electromagnetic clutches or brakes 7 which are controllable by means of a closed control loop for delivery of opposite controlled positioning moments to the inert mass. The closed loop controller receives as reference inputs desired values of one or more quantities 4 from a main stabilising controller 3. At least one controller characteristic is varied in dependence on at least one measurable quantity of the control system as a whole. <IMAGE>

Description

SPECIFICATION Apparatus for positioning and attitudestabilising an inert mass pivotably mounted on a movable base The invention relates to an apparatus for positioning and attitude-stabilising an inert mass pivotably mounted on a movable base, including at least two electromagnetic clutches or brakes which are controllable by means of a closed control loop for delivery of respectively-opposite controlled positioning moments to the inert mass, wherein the closed loop controller receives as inputs reference signals from a main stabilising controller, as is described in our British Patent Specification No. 8040654 to which reference is made.

An inert mass, e.g. a tubular weapon, mounted on a movable base, e.g. a vehicle hull, can be held in a desired spatial direction or turned out of it if a positioning device is provided which transmits positioning moments to the inert mass. A control device must ensure that the positioning moments are transmitted from the adjusting device to the inert mass independently of the desired spatial position. To improve the control process, generally not only the spatial position of the inert mass is fed to the control device but also various further measured quantities (subsidiary control quantities) which represent the current state of the control circuit.

In the positioning device in accordance with patent application 8040654 each positioning moment is produced by exciting the electromagnetic winding of at least one electromagnetic clutch or brake to produce a frictional moment, varying with the winding current, between two friction surfaces of the clutch or brake one of which friction surfaces is driven by a rotary drive.

According to the size of the electromagnetic clutches or brakes used, the change of the frictional moment is associated with a more or less large time delay. A shortening of the time delay can be achieved by the control of the positioning moment or of a quantity changing with the positioning moment, e.g. the winding current or magnetic field, as is described in patent application 8040654. Thus the magnetic field at the clutch is measured and compared with a reference value predetermined by the main stabilising controller. The difference between the actual field strength and that predetermined by the main controller and called the desired value, is thus determined and amplified in an amplifier.

In accordance with the set amplification factor there will be a higher voltage at the magnetic winding than would be necessary to produce the necessary moment if there is a difference present between the desired and actual values of the field strength. Such a construction of the control would imply that at a given value of the amplification a given magnitude of voltage can be put on the winding, and that thus the delay time between a change of the desired value for the magnetic field and the build-up of the magnetic field can be shortened to a given extent. Since however the supply voltage available can only adopt a limited value the over-excitation of the magnetic winding achievable is limited.At a constant supply voltage and high amplification of the field control loop it follows that the over-excitation factor is dependent on the change of the desired value of the field.

The lowest over-excitation would accordingly result when the greatest change in the magnetic field was desired. The over-excitation of the magnetic winding on the other hand would be greatest for very small changes in the desired value of the magnetic field.

It is an object of the invention to construct an apparatus of the type described above in which the differing periods of time, dependent on the change of moment, for the build-up of the positioning moments by the controlled electromagnetic clutches or brakes, in the sense of achieving a rapid response to a disturbance of the primary control quantity, for example the angle, are taken into account.

To solve this problem it is provided in accordance with the invention that least one controller characteristic is altered in dependence on at least one measurable quantity of the control system as a whole, for example a quantity of the closed control loop in which the electromagnetic clutches or brakes are inserted.

The 'controller characteristic' is in this connection to be understood, in accordance with the type of the controller, as a P-component, Icomponent, a D-component, whereby individual or all components can be varied in accordance with the invention.

Here, the P-component is the component of proportionate control, the I-component is the component of integrated control, and the Dcomponent is the component of lead control.

By means of the invention a so-called adaptive control is thus achieved in which the controller setting is chosen for a small variation range of the control quantities, rather than for large variations, in the sense of providing as rapid as possible a control of disturbances in the primary control quantity.

The measurable quantity can be a desired value from the main or a subsidiary control loop.

Preferably however the measurable quantity chosen is the control deviation, or the output of the main stabilising controller.

In one form of the invention, the control amplification factor of the said controller characteristic is switched from one value to another value in response to the said measurable quantity exceeding or falling below a threshold value.

Alternatively, however, the control amplification factor of the said controller characteristic is continuously varied in dependence upon the said measurable quantity.

For the adjustment of the control of the main stabilising controller the time delay of the final positioning element is of absolutely critical significance. In accordance with a further feature of the invention, for small delay times of the final control member an adjustment with high amplification factors is chosen whereby smaller control deviations result on the inert mass on the occurrence of disturbance effects. For larger time delays the control amplifications are conveniently chosen weaker with the consequence of a slower equalisation of disturbances in order avoid surging of the control loop.

The disturbance moments necessary to control disturbances are, for stabilising installations, far below the maximum control moments which can be exerted by the final control member. The control loop can accordingly be set more favourably for the normal operating state, i.e. with larger control amplification, than it must be set for the cases where larger control moments are necessary, e.g. in the case of aligning processes or extremely high disturbances.

The invention may be carried into practice in various ways, but one specific embodiment thereof will now be described by way of example only and with reference to the accompanying drawing, whose single figure shows a block circuit diagram of a control system incorporating a closed control loop, which may advantageously be used to control electromagnetic clutches or brakes in an apparatus for positioning and attitude-stabilising an inert mass, in example a tubular weapon, pivotably mounted on a movable base, for example, a vehicle hull, as described in our aforesaid British Specification No. 8040654.

In the diagram, 1 designates the desired value of the primary control quantity, in the present case conveniently a spatially fixed angle at which the inert mass is required to remain aligned independently of movement of the base. 2 is the control deviation between the desired value 1 and the actual value 10 of the primary control quantity, which deviation 2 is supplied to a main stabilising controller 3. The controller output voltage 4 is fed as a reference value to a comparison point 1 5 to which is also fed an actual value of a subsidiary control quantity 11, in the present case the magnetic field strength of an electromagnetic brake or clutch 7 for applying positioning toques to the inert mass 9. From the comparison of these values by a device at 1 5 a subsidiary control deivation signal 15A is derived which is fed to a subsidiary controller 5.The output 6 of this subsidiary controller 5 is for instance the winding voltage of the electromagnetic clutch or brake 7. The clutch or brake 7 delivers a control positioning moment 8 which is applied to the inert mass 9 to be pivoted.

10 designates the actual value of the primary control quantity, in the present case the stabilising angle. As well as the control deviation input 2, the main stabilising controller 3 receives as an additional input 12, the value of a measurable quantity of the control system, which has an influence on the effective time delay of the controlled clutch or brake 7. In dependence on the input signal 12 derived from this measurable quantity, the amplification characteristic of the main stabilising controller 3 is varied. For instance the measurable quantity which provides the input 12 may be the control deviation 2 of the main stabilising controller 3, or its output 4.

Claims

1. Apparatus for positioning and attitudestabilising an inert mass pivotably mounted on a movable base, including at least two electromagnetic clutches or brakes which are controllable by means of a closed control loop for delivery of respectively-opposite controlled positioning moments to the inert mass, wherein the closed loop controller receives as reference inputs desired values of one or more quantities from a main stabilising controller, and in which at least one controller characteristic is varied in dependence on at teast one measurable quantity of the control system as a whole.

2. Apparatus as claimed in Claim 1, including means for switching the control amplification factor of the said controller characteristic from one value to another when the said measurable quantity of the control loop exceeds or falls below a threshold value.

3. Apparatus as claimed in Claim 1, in which the control amplification factor of the said controller characteristic is continuously altered in dependence on one or more measurable quantities of the control loop.

4. Apparatus as claimed in any one of Claims 1 to 3, in which the said measurable quantity is the control deviation of the main stabilising controller.

5. Apparatus as claimed in Claim 1, in which the said measurable quantity is a quantity of the closed control loop in which the electromagnetic brakes or clutches are inserted.

6. Apparatus as claimed in Claim 5, in which the said measurable value is the output delivered by the main stabilising controller to the closed control loop.

7. Apparatus as claimed in any one of Claims 1 to 6, in which at small delay times an adjustment with large amplification factors is effected and at large delay times an adjustment with smaller amplification factors is effected.

8. Apparatus for positioning and attitudestabilising an inert mass, substantially or specifically described herein with reference to the accompanying drawing.