auto tuning is a function that automatically calculates and sets the PID constant used for PID control.

In PID control, the operation variable (MV) is determined from the deviation between the setpoint (SV) and the measured value (PV). The response of control system changes depending on how much the PID (Particle, Indicator, and Display) functions are controlled.

For example, even when control the same temperature of 200°C, a small heating tank and a large heating furnace will have different rates of temperature increase and different timeframes for temperature changes to appear after operation.

Therefore, the same PID constant cannot be used for all equipment. auto tuning uses the response of control system to determine the PID constant.

Determining PID constant requires understanding how control system responds to operation.

auto tuning calculates PID constant using the response of control system when it is actually operating.

The important point is that the PID constant are not determined solely within the controller; the response of the connected control object also influences the calculation of the PID constant.

auto tuning is one method for setting and reviewing PID constant.

When setting up new equipment

With new equipment, it can be difficult to determine the appropriate PID constant for the control system. In such cases, AT (Automatic Transmission) can be used to determine the PID constant.

When control object or equipment conditions change

If the equipment configuration, heaters, or control systems change significantly, the previously used PID constant may no longer be suitable.

In such cases, AT (Automatic Trigger) is one way to revise the PID constant.

When is it necessary to review the PID constant?

If you determine that the current PID constant are not suitable for control system, you can use AT to recalculate the PID constant.

Automatic transmissions (ATs) utilize the response of the control object. Therefore, it is assumed that control loop itself is functioning correctly.

Is the sensor measuring correctly?

If the PV (Psychological Volume) is incorrect, it's impossible to use its response to determine the appropriate PID constant. Check the sensor status, mounting location, wiring, etc.

Are the heaters and operation devices working properly?

Even if the controller outputs MV, the correct response from control object cannot be obtained unless that operation is reflected in the actual equipment.

We will also check the operation equipment used in the facility, such as heaters, thyristor regulators, SSRs, and valves.

Is control object in a state where it can actually operate?

Since AT utilizes the response of control object, it must be performed while the equipment is actually operational.

Are there any problems with temperature changes during automatic transmission?

In automatic transmissions (ATs), temperature changes may differ from normal stable control in order to verify characteristic of control object.

Before implementation, we check to ensure that no unacceptable temperature changes occur in products, materials, equipment, etc.

When automatic transmission (AT) is started, the controller determines the PID constant while monitoring the response of control system.

The automatic transmission (AT) is currently in the stage of verifying characteristic of control system in order to determine the PID constant.

Therefore, instead of simply looking at the temperature waveform during automatic transmission (AT) operation and concluding that "control is poor," we check control response after the AT has finished.

The specific actions performed during automatic transmission (AT) operation vary depending on the controller and AT system.

Starting an automatic transmission (AT) does not necessarily mean that the PID constant can be determined for any control system.

The response of control object is too slow.

In equipment with very large heat capacity, it can take a long time for the PV to change after operation is performed.

In control systems with extremely slow response times, the automatic timing (AT) may take a long time, or the PID constant may not be determined correctly.

control object's response is too fast.

Conversely, even with control systems where the PV changes very rapidly in response to operation, the controller's AT may not be able to calculate the PID constant correctly.

The calculation result does not fall within the range that can be handled by the controller.

Depending on characteristic of control system, the PID constant calculated by the automatic transmission (AT) may not fall within the range that can be set by the controller.

Once the automatic transmission (AT) test is complete, we will actually operate the vehicle with those PID constant and check control response.

The completion of the automatic transmission (AT) process does not mean that the desired control has been achieved. It is important to verify the actual control response.

The PID constant obtained by AT are values calculated using the response of the control system.

However, the PID constant determined by the automatic transmission (AT) may not be optimal for all driving conditions.

control response may change if the SV (stress coefficient), materials, load, ambient temperature, equipment conditions, etc., change.

Therefore, after the automatic transmission (AT) is completed, the PV and MV values are checked under actual driving conditions. If the control response is not as intended, the PID constant may be further adjusted.

Neither option is a choice between the two.

You can use this by performing an automatic transmission (AT) to calculate the PID constant, then actually driving the vehicle to check the PV and MV values, and finally adjusting the PID settings as needed.

What is PID tuning? The basics of tuning from the perspective of temperature control waveforms.

AT is a function for determining PID constant. It cannot solve problems caused by factors other than PID constant using AT alone.

Most CHINO controllers come standard with auto tuning function.

On the other hand, auto tuning method, execution conditions, operation method, method for registration calculated PID constant, and judgement condition when PID constant cannot be calculated correctly vary depending on the model.

This article explains the general concepts of automatic transmissions (AT). For specific operation instructions and setting conditions for individual models, please refer to the instruction manual or FAQ for each controller.