You can autotune your system following these steps:

Ebsp200 Pid Auto Tune Kit

PID Once your kettles and panel are setup, for an effective use of your panel, you need to auto-tune your HLT PID controller. This insures proper calcs resulting in efficient use of the heating element(s). You only need to do this for your HLT PID. To start the auto tune process, bring your kettle to approximately 150 degrees, once close, press the. Jan 29, 2016  Auto-tuning PID capabilities in temperature controllers solve most problems if used properly, but they do not always work as desired. Sometimes, a good old. PITOPS is modern and unique Primary PID Tuning and Advanced Process Control design and optimization software which works entirely in the closed-loop mode without any step-test in the time domain. Unlike competitor PID controller software, Pitops-PID works from fast millisecond scan times to seconds, minutes, and multiples of minutes.

1. Set the folder permission of /home/pi/craftbeerpi to 777 (chmod) (this is to allow a file to be written later)
2. In the kettle setup, select PIDAutotuneLogic as automatic logic
3. Set a temperature setpoint. Usually something between 50°C to 60°C works well.
4. Add the amount of water you usually use
5. If you use a pump, turn it on
6. Enable automatic control (the car symbol)
7. Wait until the autotune-logic disables automatic control itself

This can take up to an hour or more (depending on the individual hardware setup and the setpoint temperature), because the autotune logic tries to oscillate around the setpoint.
The problem is, that after overshooting the setpoint, the autotune-logic waits until the temperature drops below the setpoint which usually takes some time.

During tuning, you can read the autotune log by reading the craftbeerpi logfile and filtering for PIDAutotune:
tail -f craftbeerpi/log/name_of_the_logfile | grep PIDAutotune

After the autotune-process is completed successfully, the results will be saved to a file named pidparams.txt in the craftbeerpi working directory (usually: craftbeerpi/pidparams.txt).
The autotune-process can fail. In this case, the automatic mode will be disabled, but no pidparams.txt file will be created.If autotune runs forever, the problem is usually either the heater being not powerful enough to reach the setpoint or the temperature not dropping below the setpoint fast enough for whatever reason (isolation, ambient temp. etc.).

Hint: If you aren't sure how auto tuning works, you can do a dry run on this brewing kettle simulation.

• output step %: defines the the output of the autotune-algorithm when stepping up/down, e.g. output step = 100; step up (=heating) output = 100; step down (= cooling) output = -100. This setting should stay at 100%
• lookback seconds: determines how far the algorithm will look back when trying to find local (temperature) extrema (minima/maxima). If the algorithm recognizes even short peaks as extrema, you should increase this value. If it doesn't recognize actual extrema, you should decrease it. Usually the default of 30 seconds work fine.
• max. output %: limits the maximum power output. This is useful if your heater is overpowered and would heat up the kettle way too fast. If you don't want to limit your heater, leave this at the default value of 100%

The PID-tuning rules basically are different ways of calculating the PID-parameters, which changes the behavior of the PID-controller (e.g. ziegler-nichols produces quite a lot of overshoot - not that good for brewing). See Ziegler–Nichols method.In most cases, brewing is the best rule for brewing, obviously ;)

Example of pidparams.txt file:

PID tuning refers to the parameters adjustment of a proportional-integral-derivative control algorithm used in most repraps for hot ends and heated beds.

PID needs to have a P, I and D value defined to control the nozzle temperature. If the temperature ramps up quickly and slows as it approaches the target temperature, or if it swings by a few degrees either side of the target temperature, then the values are incorrect.

To run PID Autotune in Marlin and other firmwares, run the following G-code with the nozzle cold:

This will heat the first nozzle (E0), and cycle around the target temperature 8 times (C8) at the given temperature (S200) and return values for P I and D. An example from http://www.soliwiki.com/PID_tuning is:

For Marlin, these values indicate the counts of the soft-PWM power control (0 to PID_MAX) for each element of the control equation. The softPWM value regulates the duty cycle of the f=(FCPU/16/64/256/2) control signal for the associated heater. The proportional (P) constant Kp is in counts/C, representing the change in the softPWM output per each degree of error. The integral (I) constant Ki in counts/(C*s) represents the change per each unit of time-integrated error. The derivative (D) constant Kd in counts/(C/s) represents the change in output expected due to the current rate of change of the temperature. In the above example, the autotune routine has determined that to control for a temperature of 200C, the soft PWM should be biased to 92 + 19.56*error + 0.71 * (sum of errors*time) -134.26 * dError/dT. The 'sum of errors*time' value is limited to the range +/-PID_INTEGRAL_DRIVE_MAX as set in Configuration.h. Commercial PID controllers typically use time-based parameters, Ti=Kp/Ki and Td=Kd/Kp, to specify the integral and derivative parameters. In the example above: Ti=19.56/0.71=27.54s, meaning an adjustment to compensate for integrated error over about 28 seconds; Td=134.26/19.56=6.86s, meaning an adjustment to compensate for the projected temperature about 7 seconds in the future.

Ebsp200 Pid Auto Tune Download

The Kp, Ki, and Kd values can be entered with:

In the case of multiple extruders (E0, E1, E2) these PID values are shared between the extruders, although the extruders may be controlled separately. If the EEPROM is enabled, save with M500. If it is not enabled, save these settings in Configuration.h.

For the bed, use:

and save bed settings with:

For manual adjustments:

• if it overshoots a lot and oscillates, either the integral gain needs to be increased or all gains should be reduced
• Too much overshoot? Increase D, decrease P.
• Response too damped? Increase P.
• Ramps up quickly to a value below target temperature (0-160 fast) and then slows down as it approaches target (160-170 slow, 170-180 really slow, etc) temperature? Try increasing the I constant.

See also Wikipedia's PID_controller and Zeigler-Nichols tuning method. Marlin autotuning (2014-01-20, https://github.com/ErikZalm/Marlin/blob/Marlin_v1/Marlin/temperature.cpp#L250 ) uses the Ziegler-Nichols 'Classic' method, which first finds a gain which maximizes the oscillations around the setpoint, and uses the amplitude and period of these oscillations to set the proportional, integral, and derivative terms.

Saving PID settings

You will need to commit your changes to EEPROM or your configuration.h file for them to be permanent.

To save to EEPROM use:M500

Modifying Marlin Autotune parameters

The default Marlin M303 calculates a set of Ziegler-Nichols 'Classic' parameters based on the Ku (Ultimate Gain) and the Pu (Ultimate Period), where the Ku and Pu are determined by searching for a biased BANG-BANG oscillation around an average power level that produces oscillations centered on the setpoint. (See https://github.com/ErikZalm/Marlin/blob/Marlin_v1/Marlin/temperature.cpp#L238 )

You can transform these 'Classic' parameters into the Zeigler-Nichols 'Some Overshoot' set with:

Ebsp200 Pid Auto Tune Free

Or the Z-N 'No Overshoot' set:

Note that the multipliers for the autotuning parameters each have only one significant digit (implying 10% maximum precision), and that the other schemes differ by factors of 2 or 3. PID autotuning and tuning isn't terribly precise, and changes in the parameters by factors of 5 to 50% are perfectly reasonable.

In Marlin, the parameters that control and limit the PID controller can have more significant effects than the popular PID parameters. For example, PID_MAX and PID_FUNCTIONAL_RANGE, and PID_INTEGRAL_DRIVE_MAX can each have dramatic, unexpected effects on PID behavior. For instance, a too-large PID_MAX on a high-power heater can make autotuning impossible; a too-small PID_FUNCTIONAL_RANGE can cause odd reset behavior; a too large PID_FUNCTIONAL_RANGE can guarantee overshoot; and a too-small PID_INTEGRAL_DRIVE_MAX can cause droop.

PID Tuning by Commercial PID

If you have access to a PID controller unit and a compatible thermal probe that fits down into your hotend, you can use them to tune your PID and calibrate your thermistor.

Ebsp200 Pid Auto Tune Reviews

Connection of the output of the PID to your heater varies depending on your electronics. (I used a 1K2:4K7 voltage divider to drop the 22V output of the PID to 5V for my bread-boarded VNP4904)

After the PID is connected you can use it to measure the nozzle temperature and correlate it with the thermistor readings and resistances.

Conversion from the commercial PID values of kP in %fullscale, Ti in seconds, and Td in seconds is as follows:

As an example, a $30 MYPIN TD4-SNR 1/16 DIN PID temperature controller and $10 type-K probe can hold a particular Wildseyed hotend with a 6.8ohm resistor at 185.0C+/-0.1C using 12V with about a 43.7% duty cycle, or 0.437*12*12/6.8=9.25W. Invoking the autotuning on the controller produces these parameters: P=0.8%/C, I=27s, D=6.7s. Converting these to Marlin PID values:

Differences between the results can be caused by physical differences in the systems, (e.g: the thermocouple is closer to the heater than the thermistor,) or by different choices of autotuning parameters (e.g.: the MYPIN TD4 autotuning process is a proprietary black box, while Marlin uses Zeigler-Nichols 'Classic' method.)

The Temperature/resistance table below was developed by using the PID+thermocouple system to set temperatures on a sample hotend by controlling the heater while measuring the thermistor resistance. These values can be used with Nophead's http://hydraraptor.blogspot.com/2012/11/more-accurate-thermistor-tables.html or Marlin's https://github.com/ErikZalm/Marlin/blob/Marlin_v1/Marlin/createTemperatureLookupMarlin.py to create calibrated thermistor tables. The PID column collects the autotuning values produced by the PID controller for the indicated temperature. The kP,Ki,Kd lists the converted parameters.