Automatic pneumatic pressure control apparatus and method of controlling same
AssigneeSMC Corporation
InventorsKenji Irokawa, Tomohiko Aki
Life of this patent
Estimating the term…
Abstract
When a reference signal is changed stepwise, a switch is open, and a pneumatic device with a dead time starts being actuated in a PD control mode. After elapse of the dead time, when a controlled variable changes and a position detector produces an output signal, a speed signal which is a differential of a feedback signal changes from a value "0". When a speed detector detects when the speed signal is equal to or greater than a predetermined value, a switching signal is applied to close the switch. After the switch is closed, the pneumatic device is actuated in a PID mode. An overshoot or an oscillation in a controlled variable due to the integration of the dead time in an I control mode can be suppressed.
Claims16
A method of controlling an automatic pneumatic pressure control apparatus which detects, with a detector, an output controlled variable from a pneumatic device actuated by a manipulated variable signal, converts the output controlled variable into a feedback quantity, automatically controls the pneumatic device depending on an error based on the feedback quantity and a reference signal, and generates said manipulated variable signal, comprising the steps of:
- changing said reference signal stepwise from a first value to a second value thereby to change the output controlled variable from said pneumatic device from a given value to a desired value;
- supplying said manipulated variable signal in a PD control mode to said pneumatic device at an initial time when said reference signal changes stepwise from the first value to the second value;
- and
- operating a switch configured to activate an integrator circuit, thereby changing from said PD control mode to a PID control mode and supplying said manipulated variable signal in said PID control mode to said pneumatic device, said switch being operated when a differential of said output controlled variable reaches a predetermined value at a time after said initial time.
An automatic pneumatic pressure control apparatus comprising:
- a computer being supplied with a reference signal and a feedback signal and configured to output a manipulated variable signal depending on an error based on the feedback signal and the reference signal;
- a pneumatic device actuatable by the manipulated variable signal;
- a detector configured to detect an output controlled variable produced by the pneumatic device and to convert the detected output controlled variable into a feedback quantity,
- wherein said reference signal is changed stepwise from a first value to a second value thereby to change the output controlled variable from said pneumatic device from a given value to a desired value;
- and
- said computer comprises,
- means for supplying said manipulated variable signal in a PD control mode to said pneumatic device at an initial time when said reference signal changes stepwise from the first value to the second value, and
- means for changing from said PD control mode to a PID control mode and supplying said manipulated variable signal in said PID control mode to said pneumatic device when a differential of said output controlled variable reaches a predetermined value at a time after said initial time.
Dependencies are inferred from the claim text.