Logic controlled integrator

#The present invention relates to an integrator, the input signal of which is arranged to be controlled by certain logic conditions.

#In control system, it is previously known to utilize linear integrator, which are then usually included in a so-called PID filter. In control systems of the kind in which changes of speed occur, said linear integrators give satisfactory results, while in control systems of the third order, disturbances that occur in the form of changes of acceleration give rise to tracking errors in the system. Particularly in control systems of the kind where an operator is to keep an observation device in the form of a sight, a telescope, radar, IR equipment etc. continuously directed against an object which moves in relation to the observation device, it is usual that such disturbances occur. These disturbances then occur primarily when flying targets pass on a straight course in relation to the observation device.

#The purpose of the present invention is therefore to achieve an integrator with the aid of which it is possible to reduce the tracking error that occurs in control systems of the above-mentioned kind. The input signal to the integrator is then controlled by certain logic conditions, and the device has been given the characteristics indicated in the claims.

#The invention will be described in more detail with reference to the accompanying figures, in which

#FIG. 1 shows a block diagram of the invention,

#FIG. 2 shows a block diagram for switching between two different amplification factors,

#FIG. 1 shows an integrator 1, the input of which is connected to a switch 2. When the switch is closed, an input signal e.sub.in is fed to the integrator, and when the switch is open there is no input signal on the input of the integrator. The input signal e.sub.in is also fed to a logic circuit 3 which controls the switch 2. With the aid of the logic circuit 3 it is possible to control the time of operation of the integrator. When the input signal consists of a periodic signal, it is thus possible to allow the input signal to be connected to the integrator only during a certain part of the period. As the integrator is not connected during the whole of the period, however, the amplitude of the output signal e.sub.ut will be lower than in the case at linear integration. However, the amplitude can easily be adjusted by raising the amplification factor K.sub.I.

#Further, the logic controlled integrator gives less phase shifting compared with a linear integrator, which usually is an advantage in control systems.

#FIG. 2 shows a variant of the device according to FIG. 1. In this case, the input of the integrator is connected to two amplifiers 4, 5, with different amplification factors (K.sub.I1 and K.sub.I2). As in FIG. 1, the switch 2' is controlled by a logic circuit 3' for connecting the different amplifiers. The device according to FIG. 1 constitutes a special case of FIG. 2, in which one of the amplification factors is zero.