Control system for doser actuator

A control system for a doser actuator having a supply solenoid administering doses of fluid to a control chamber to move an actuator member in one direction and a return solenoid withdrawing doses of fluid from the control chamber to move the actuator member in the other direction, said control system comprising:

• means for generating an error signal proportional to the difference between an actual position signal and a requested position signal;
• means for generating a base pulse width signal as a function of said error signal;
• means for generating a correction signal whenever said error signal is within a predetermined band;
• and
• means for generating a total pulse width control signal at periodic intervals from the combination of said base pulse width signal and said correction signal wherein said total control signal regulates the opening and closing times of said solenoids to move the actuator member in a direction to null said error signal.

A control system for an actuator member comprising:

• means for generating a position request signal proportional to a desired position of the actuator member;
• means for generating an actual position signal of the opposite polarity of said position request signal and proportional to the actual position of the actuator member;
• a first summing junction for combining said actual position signal and said position request signal and for generating an error signal proportional to the difference therebetween;
• a polarity sensor for determining the polarity of the error signal, for generating a unity multiplier factor if the error signal is of one polarity and for generating a negative unity multiplier factor if the error signal is of the other polarity;
• first multiplier means, receiving the outputs from the polarity sensor and summing junction, for generating an absolute error signal proportional to the product of said outputs;
• a function generator for generating a base pulse signal as a function of said absolute error signal;
• a selector circuit responsive to said error signal and a periodic timing signal, for generating a reset signal synchronously with said timing signal if said error signal is not within a predetermined band;
• a counter, being cleared by said reset signal, incrementing in response to said periodic timing signal;
• means for generating a correction signal proportional to the count of said counter;
• a second summing junction for combining said correction signal and said base pulse signal to form a total pulse signal;
• pulse generator means for generating pulses at the periodic rate of said timing signal and proportional to said total pulse signal;
• second multiplier means, receiving outputs from polarity sensor and pulse generator means, for generating pulses of different polarities depending upon which unity multiplier factor is output from said polarity sensor;
• and
• means for gating said polarized pulses, depending on their polarity, to either a first control means moving the actuator member in one direction or to a second control means moving the actuator member in the opposite direction.