PID controller tuning – With motor and gear example

Understanding the process is the basis for getting a well-designed control node. The sensors must be in the right location and the valves of the correct size and position.

In general, for the best node control, dynamic controller gain must be as high as possible without causing node instability. Controller gain selection is done easily through PID Tuning Software (PID Tuning Software) setup software.

PID control:

PID control (proportional, integral, derivative) is not as complicated as imagined, many control problems can be solved by simple controllers, without using difficult mathematical control theory. The technique used to set the controller is to try and match methods that can be applied to almost all control problems successfully.

The PID controller can be applied with mechanical, pneumatic and electronic equipment. Digital PID controllers use microprocessors and coding. Each PID element is a basic element with each function and effect on the system. The three PID elements are run by a combination of system commands and feedback from controlled objects (commonly called “plants”).

To produce system output. The following figure shows a block diagram of a basic PID controller, whose derivative elements are executed only from the plant feedback. This plant feedback is compared to the command to get an error. This error signal runs proportional and integral elements. The resulting signal is summed together to run the plant. Make replacement connections for proportional elements (dashed lines); can be better, depending on how the system responds to commands.

In order to better understand, several examples of the application system are needed, and see the effect of using various controllers on it:

  • A driving motor a gear train
  • A precision positioning system
  • A thermal system

Each of these systems has different characteristics and requires different control strategies for getting the best performance.

Motor and gear

The motor moves the gear system, the final position of the gear is measured with a potentiometer or other position reader. It is seen, this mechanism drives the printer, or throttle mechanism in the automobile control system, or almost any general precision position controller. The following figure shows a system diagram like that. The motor is run with a voltage controlled by the software. The motor rotation is lowered to drive the actual mechanism. The final position that is driven is measured by a potentiometer.

A DC motor that is run with a fixed voltage will be proportional to the existing voltage. Usually, the motor armature has a resistance that limits the ability to be accelerated so that the motor experiences a delay (delay) between the input voltage changes and the resulting rotation changes.

A series of gear (gear train) utilizes motor rotation and multiplies it by a constant. Finally, the potentiometer measures the position of the output shaft. The figure below shows the combined response stages of teeth and motors, with a time constant of t0 = 0.2 s. The step response of the system is the output behaviour in response to an input that moves from zero to several constant prices at time t = 0. Because it deals with a generic example, here is shown the action response as a fraction of the full scale, so become one. The picture shows the step input and motor response. The motor response starts out slowly according to the time constant, but once the response goes out of its way, the motor position slides at a steady speed.


Instrumentation Engineer

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