Control mode switching circuit
AssigneeMTS Systems Corporation
InventorJohn O. Dollerschell
Life of this patent
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Abstract
A "mode switch" is used for smoothly switching a servovalve controlled device such as an SMC press, in particular, from control under one parameter to control by another. The mode switch provides a very smooth transfer of control from displacement control between two relatively movable parts to force control to provide for controlling the force exerted by actuators acting between the two parts. The mode switch electronically tracks the signals so that when the switching is made the signals are precisely equal to prevent abrupt changes in the control signals. This smooth transfer is achieved even under active control, that is when both control signals are changing in value.
Claims7
A circuit for providing a transfer of input parameters between first and second input signals to provide a command output signal at an output terminal without discontinuity in the output signal during the transfer including means for providing the first and second input signals respectively, a first integrator having first and second inputs, a differential amplifier, first and second switch means, the first switch means being coupled for controlling input of said first signal to the first input of the integrator when closed, the first switch means being open in a first position and the second switch means then being closed, said second switch means being coupled for connecting the output of said differential amplifier to the first input of said integrator when closed;
- the second input of the integrator being connected to a reference;
- means connecting the output of the integrator to a first input of said differential amplifier;
- third and fourth switch means, said third switch means being open when the fourth switch means is in a closed position and closed when the fourth switch means is open, said third switch means when closed being coupled for connecting the output of the integrator to the output terminal, and said fourth switch means being operable when closed for connecting the second input signal to the output terminal;
- means connecting the second input of said differential amplifier to receive the second input signal;
- and
- the second and fourth switch means being closed so that the output of the integrator will be driven in a direction to cause the differential amplifier output to equal the reference at the second terminal of the integrator and therefore the integrated output tending to follow the second input signal so that at the time of switching, when the second and fourth switch means are opened and the first and third switch means are closed, the integrator output will be at substantially the same level as the second input signal, the first input signal thereafter acting through the integrator, the output of which is at a level equal to the second input at the time of switching.
A circuit for providing a transfer of input parameters between first and second input signals to arrive at a command output signal without discontinuity in the output signal, including means for providing the first and second input signals respectively, a first integrator having an input, a differential amplifier sensing the difference between two inputs thereof, the first switch means controlling coupling and decoupling of said first signal to the input of the integrator, and in an alternate mode coupling and decoupling the output of said differential amplifier to said integrator;
- means connecting the output of the integrator to a first input of said differential amplifier, means connecting the second input signal to one of the inputs of the differential amplifier, second switch means coupling and decoupling the output of the integrator to a circuit output and in an alternate mode coupling and decoupling the second input signal to the circuit output;
- and means to control the switch means to couple the integrator output to the circuit output only when the integrator output and second input signals are substantially equal, and to couple the second input signal to the circuit output only when the integrator output is substantially equal to the second input signal.
Dependencies are inferred from the claim text.