Remote controller for controlling apparatus by diverting feedback signal from native controller to the remote controller and methods for same
A remote controller can be provided on any apparatus that employs feedback control from a native controller to add functionality to the apparatus where the native controller is not capable of providing such functionality independently.
1. A method of controlling a controlled variable of an injection molding apparatus via a remote controller configured via a retrofitting to a native controller of the injection molding apparatus, the injection molding apparatus comprising a heated barrel, an injection shaft, and an actuation unit, the actuation unit being operably coupled with the injection shaft and configured to facilitate an operation of the injection shaft with respect to the heated barrel, the native controller prior to the retrofitting being configured to control the operation of the actuation unit via a first control algorithm based upon a feedback signal, and the method comprising:
sensing the controlled variable of a molding process at a sensor;
generating the feedback signal by the sensor based upon the controlled variable;
at the remote controller:
receiving the feedback signal;
comparing the controlled variable of the molding process to a desired controlled variable setpoint;
generating a control signal via a second control algorithm based upon the controlled variable and the desired controlled variable setpoint;
combining the control signal and the feedback signal into a modified feedback signal; and
transmitting the modified feedback signal to the native controller in lieu of the feedback signal; and
at the native controller, controlling the operation of the actuation unit via the first control algorithm based at least in part upon the modified feedback signal, to thereby modify the control of the operation of the actuation unit performed at the native controller.
2. The method of claim 1 wherein:
sensing a controlled variable of the molding process comprises sensing a melt pressure of the injection molding apparatus;
comparing the controlled variable of the molding process to the desired controlled variable setpoint comprises comparing the melt pressure of the injection molding apparatus to a desired melt pressure setpoint; and
generating the control signal comprises generating the control signal based upon the melt pressure and the desired melt pressure setpoint.
3. The method of claim 2 wherein:
sensing the controlled variable of the molding process comprises receiving a signal from the sensor;
sensing the melt pressure comprises:
receiving a melt pressure signal from the sensor; and
determining a value for the melt pressure based upon the melt pressure signal; and
generating a control signal based upon the melt pressure and the desired melt pressure setpoint comprises:
defining the desired melt pressure setpoint for the melt pressure; and
comparing the desired melt pressure setpoint to the value of the melt pressure.
4. The method of claim 1 , wherein the controlled variable of the molding process comprises one or more of a melt pressure and a cavity pressure.
5. The method of claim 1 wherein the injection shaft comprises a reciprocating screw.
6. The method of claim 5 wherein controlling the operation of the actuation unit based upon the modified feedback signal comprises controlling a reciprocation of the reciprocating screw.