Patent Application
20180195837
The present invention r AIMING elates to motor-driven aiming or steering of an element in a predetermined direction, and in particular to aligning a weapon on a line of sight.
It is known to mount an aiming device comprising a stationary structure and a steerable support on a weapon system that is steerable relative to a reference frame such as that of the vehicle carrying the weapon system if it is a motor-driven weapon system. The support of the aiming device is mounted on the structure of the weapon to be steerable about two axes of rotation, namely an elevation axis and a bearing axis, by means of two electric motors.
The motors are controlled so as to bring the steerable support into alignment on a direction corresponding to the line of sight determined by the sight setter of the weapon and so as to maintain the alignment.
When firing, the recoil of the weapon produces an impact that causes the support to turn suddenly. The motors are controlled to oppose this sudden turning until the control of the motors becomes saturated, thereby limiting the risk of damaging the electronics of the device, but making it impossible to maintain the alignment of the support on the line of sight. There then arises an offset between the real angular position of the support and the line of sight. The control of the motors does not enable the motors to take up this offset quickly, such that in the event of a burst of fire, there is a risk that the second shot and the subsequent shots will be further and further away from the target.
An object of the invention is to provide means making it possible to improve the accuracy with which a motorized support is aligned in the event of an impact or any other physical phenomenon that leads to the motor becoming saturated.
To this end, the invention provides a method of controlling an aiming device comprising a stationary structure having mounted thereon a support so as to be steerable about at least one axis of rotation by means of at least one motor, the support being provided with at least one inertial sensor of angular speed about that axis, the method comprising the steps of:
In the event of the motor saturating, the reference inertial position is the position in which the support was to be found immediately prior to the motor saturating. This position is measured by the inertial sensor of angular speed. With the invention, the nominal speed setpoint is increased so as to bring the support quickly towards the reference inertial position.
The invention also provides an aiming device comprising a stationary structure having mounted thereon a support to be steerable about at least one axis of rotation by means of at least one motor connected to a control unit. The support is provided with at least one inertial sensor of angular speed about that axis, the control unit being arranged:
Other characteristics and advantages of the invention appear on reading the following description of particular, non-limiting embodiments of the invention.
Reference is made to the accompanying drawing, in which:
With reference to
The angular position of the support 2 is adjustable about the axis 3 by means of an electric motor 4 having an outlet shaft connected via motion transmission means to a ring that is coaxial about the axis 3 and that is secured to the support 2. The motion transmission means may for example be gears, a belt, cables, . . . . The motor may also be mounted to be directly engaged with the element that is to be driven, thereby connecting the structure 1 to the support 2.
The support 2 is also fitted with an inertial sensor for sensing angular speeds about the axis 3, namely a gyro 5. The electric motor 4 and the gyro 5 are connected to a computer control unit 6 arranged to run a control program and including an interface enabling an operator of the aiming device to input data into the control program. The computer control unit 6 continuously stores the angular speed measured by the gyro 5.
The operation of the control program is illustrated in
The control system comprises a main control loop 20 and a correction loop 30 that intervenes in the event of the electric motor 4 becoming saturated.
The main control loop 20 comprises a control element 21 for controlling motors that determines the control parameters for the electric motor 4 as a function of a difference between a speed setpoint {dot over (θ)}l and a speed of the support 2, written {dot over (θ)}M. The speed {dot over (θ)}M is measured by the gyro 5.
The correction loop 30 comprises an estimator 31 for estimating the difference between a reference inertial position prior to saturation and a current inertial position, and a corrector 32 that is arranged to correct the nominal speed setpoint {dot over (θ)} as a function of the difference. This correction is a correction of the proportional integral type that supplies a corrected speed setpoint {dot over (θ)}c. The correction loop 30 also has a detector 33 for detecting saturation of the electric motor 4 on the basis of saturation information coming from the control element 21. The detector 33 serves to monitor the occurrence of saturation of the electric motor 4 and it is arranged to activate the correction loop 30 in the event of the electric motor 4 saturating. A summing circuit 34 adds the nominal speed setpoint {dot over (θ)} and the corrected speed setpoint {dot over (θ)}c in order to obtain the speed setpoint {dot over (θ)}l.
Thus, in normal operation, when saturation does not occur, the speed setpoint {dot over (θ)}l is equal to the nominal speed setpoint {dot over (θ)}.
In contrast, in the event of said saturation, the correction loop 30 is activated by the detector 33 so that the nominal speed setpoint {dot over (θ)} is corrected by the corrector 32, which supplies the corrected speed setpoint {dot over (θ)}c.
Naturally, the invention is not limited to the embodiments described but encompasses any variant coming within the ambit of the invention as defined by the claims.
In particular, the support 2 may be mounted in the structure 1 so as to be adjustable in position about two mutually perpendicular axes, for example. The support 2 may be mounted in the structure 1 to be adjustable in elevation and in bearing relative to the structure 1 by means of two motors using either an inertial angle sensor having two sensing axes or else two inertial angle sensors each having one sensing axis.
The invention is applicable to any aiming device that is arranged to steer any element in a predetermined direction.
The support may be fitted with a plurality of inertial sensors: a first sensor used for the conventional stabilization control loop, and a gyro for the correction loop.
It is possible either to use an absolute reference position value, as mentioned above, or else to use the current absolute position error as calculated at each iteration of the control.
The method may be implemented continuously by adding an outer absolute (or inertial) position loop. The device for implementing the method then does not have elements for triggering and stopping the function 33; there is no reference measurement made by the estimator and the speed setpoint supplied by the operator is always corrected by the speed setpoint from the corrector 32. This implementation serves to reduce considerably the impact of friction and also to increase performance in terms of stabilizing oscillations of the servo-controlled system. The method can thus also be used as a friction compensator.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1556304 | Jul 2015 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/065586 | 7/1/2016 | WO | 00 |
