Future Design Controls PID Control Tuning Options

The information shown below is for reference only. Refer to the appropriate Users Manual prior to installing or configuring any instrumentation.

Fuzzy modified Auto-Tune provides fast process response while minimizing Process overshoot and undershoot.

                                Fuzzy logic Auto Tune

The auto-tune function allows the user to simplify initial setup for a new system or process. A clever algorithm is provided to obtain an optimal set of control PID parameters for the process and can be applied either as the process is warming up [cold start] or as the process has been in steady state [warm start].

The Fuzzy function adjusts PID parameters during the auto-tune cycle to enable the process to reach a predetermined setpoint in the shortest time with minimum overshoot and undershoot during power-up or load disturbances.

Future Design Controls 90 Series Control Platform offered the first version of our Proprietary Fuzzy modified Auto-Tune technology. With advancements in microprocessor technology and enhancements to our Fuzzy Auto-Tune algorithm the 300 Series offers the highest performance control in its' class with minimal overshoot & stability control to 0.1C.


Regardless of which Future Design Controls control platform, the Fuzzy modified Auto-Tune feature will provide High Performance Control.

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Detail on Fuzzy Assisted Auto-Tune

Fuzzy Logic is an artificial intelligence technique that allows control decisions to make upon approximate or incomplete information. Fuzzy Logic Auto-Tune is a continuous decision making function that will calculate optimum PID values for fast process response while minimizing initial overshoot and setpoint differentials.


The auto-tuning process can be performed at setpoint [warm start] or at some level below setpoint [cold start].


During a Warm Start the process will oscillate around setpoint during the tuning process. If an overshoot beyond current setpoint is likely to cause damage select a lower setpoint.


Cold Start Fuzzy Assisted Auto-Tune:


Warm-Up Cycle: When the auto-tuning begins the unit enters a Warm-Up cycle.

Waiting Cycle: As the process reaches setpoint value the unit enters Waiting cycle.

Learning Cycle: The waiting cycle elapses a double integral time then enters a Learning cycle. The double integral time is used to allow the process to reach a stable state.

Pre-Tune Cycle: Before the Learning cycle the unit performs a pre-tune function with PID control.

Post-Tune Cycle: While in Learning cycle the unit performs a post-tune function with an ON-OFF control. This Learning cycle is used to test the characteristics of the process.


The data are measured and used to determine the optimal PID values. At the end of two successive ON-OFF cycles the PID values are obtained and automatically stored in memory.


During the pre-tune stage the PID values will be modified if any unstable phenomenon, which caused by incorrect PID values are detected.


Without the pre-tune stage the tuning result will be strongly related to the point in time when the auto-tuning is applied. Hence, without pre-tune different values will be obtained every time auto-tune is completed. This is particularly true when auto-tuning are applied by using cold start and warm start.


Warm Start Fuzzy Assisted Auto-Tune

When auto-tuning begins near the setpoint [warm start] the unit passes the warm-up cycle and enters the waiting cycle. After the waiting cycle the auto-tune procedures are the same as described for cold start.


PID fuzzy logic cold start


PID fuzzy logic warm start

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Auto-Tune for 2nd Set of PID Variables and/or Setpoint - 300, P and B42 Series Controls only

The 300, P and B42 Series Controls offer a 2nd Setpoint and PID Variables [SP1 & 2 and PID1 & 2]. The 2nd set of either SP or PID are selected by configuring the 300 Series Event input to change the appropriate values when provided a dry contact closure.


The optimal PID values for a process may vary with its process value and set point. Hence if a process is used for a wide range of set point, dual PID values are necessary to optimize the control performance.


During Fuzzy Assisted Auto-Tune if the first PID set is selected (event input is not applied), the PID values will be stored in PB1, TI1 and TD1. Similarly, if the second PID set is selected (event input is applied while PID2 or SP.P2 is selected for Event Input) during auto-tuning the PID values will be stored in PB2, TI2 and TD2 as soon as auto-tuning is completed.


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Fuzzy Assist Self-Tune PID

Fuzzy Assisted Self-Tune PID [applicable to 300 Series Controls only]

The Self-Tuning feature uses an innovative algorithm providing an alternative to manual or auto-tuning the controller.


When Self-Tuning is on the controller will change the working PID values and compares the process behavior with previous cycles. If the new PID values achieve better control the next cycle changes the PID values in the same direction or if worse control changes PID in the reverse direction. When an optimal condition is obtained the PID values will be stored in memory. When Self-Tuning is completed the value SELF will be changed from YES to NONE to disable Self-Tuning function.


When the Self-Tuning is enabled the PID variables are tunes slowly so that the disturbance to the process is less than auto-tuning. When in Self-Tune mode the Fuzzy Auto-Tune may be run with the Auto-Tune PID results being used as the initial Self-Tune parameters.


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Limit Percentage Output


Limit Percentage Output for Proportional Output #1 and/or #2 [applicable to 200, 300 & P Series]


In some applications the heater [or cooler] has excessive capacity. To avoid excessive overshoot and/or undershoot you can use the Power Limit function. Power Limit is configurable to limit the maximum percent of output from 0-100%. Note: P Series Profile Controls can limit BOTH minimum & maximum percent output.



Out2=Cool, PB1=10C, CPB=50, PL2=80

Output 1 & output 2 will act as following graph:

PID limit output settingPID percentage output limit

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Manual PID Tuning & Proportional Band Offset [manual reset]

Manual PID Tuning: [applicable to C, 90, 100, 200, 300 & P Series Controls]

Manual Adjustment of Proportional Band, Integral [auto reset] and Derivative [Rate] is easily accomplished in these controls.


Proportional Band Offset -Manual Reset: [applicable to C, 90, 100, 200, 300 & P Series Controls]

Control loops with Proportional only [no Integral or Rate] or applications where there is a known control droop a manual Proportional Band Offset may be entered by the operator.


Although commonly known as Manual Reset we refer to this adjustment as "Offset".

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Heat/Cool PID Proportional Bands & Heat/Cool Dead Band [DB]

Heat/Cool PID Proportional Bands

Heating Proportional Band: The proportional band of output #1 may be set manually or by Fuzzy assisted auto-tune or self-tune. The proportional band is set in engineering units and for heat cool would be degrees F or C.


Cooling Proportional Band: CPB

The CPB is configured differently dependent upon control series.

The older 90 & 200 Series use proportional band set in the same manner as the Heat proportional band, degrees F or C.


The B, B42, C, P, 100 & 300 Series utilize a more recent technology with optimized algorithms with the CPB measured by % of Heating proportional band with ranges from 50-300 or 0-255 dependent upon control series.


The default CPB value is 100%; if more cooling required decrease CPB, if more cooling increase CPB. The value of CPB remains unchanged throughout auto-tuning.


Typically the CPB is related to the cooling media used.

CPB for Air typically 100%

CPB for Oil typically 125%

CPB for Water typically 250%


Heat/Cool Dead Band: DB

Manual Set Heat/Cool DB: [applicable to C, 90 [8130 only], 100, 200, 300 & P Series Controls]

Adjustment of DB is dependent upon system requirements and set in conjunction with PID values can provide excellent control. However, tighter control results in an overlap area over which both outputs may be active. A wider DB will avoid having both outputs active but may have significant overshoot and undershoot of SP.


Adaptive Heat/Cool DB: [applicable to 300 Series only]

The 300 Series contains a clever algorithm to optimize DB value to minimize energy consumption and provide tight control performance. The DB is implicitly contained in a program such that if the process value increases (not necessarily exceeds SP), the cooling control will provide an optimal amount of cooling to the process. If the process value decreases, the control will adjust its adaptive DB to increase the heating action and decreases the cooling action immediately. While the PV is steady the heating and cooling will not operate simultaneously to minimize energy consumption.


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Configure Relay Proportional Control Output #1 to On-Off ControlTo change Output #1 Relay output [if so equipped] from Proportional to On-Off Control set Output #1 Proportional Band [PB1] to 0.0. Hysteresis configuration will now be available for this on-off output.

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Return to:

Process & Temperature Control Page.htm

90 Series.htm

300 Series.htm

100/C Series.htm

B Series.htm (board level control)

Limit Controls.htm

P Series Profile Controls.htm

Future Design Controls   888.751.5444 csr@futuredesigncontrols.com