Editing Tuning torque controller

Torque controller tuning means finding the correct gain values for a torque controller inside the servo drive to achieve a proper response from a torque [[Setpoint signal|setpoint]] change. 

==Direct inductance & resistance setting method==
In [[Granity]], there is no dedicated torque control PI gains as the software supports entering motor coil inductance and resistance where the suitable PI gains are calculated from. 

===Method 1 (preferred)===
If you are using a drive model that supports automatic measurement of inductance and resistance, follow the instructions [[Measure motor resistance and inductance in Granity|here]].

===Method 2===
If the above measurement function is not available, and your motor comes with coil specifications containing [[phase-to-phase]] inductance and resistance values, then the only necessary step is to enter the given values into motor resistance [[MR]] and inductance [[ML]] parameter fields. In case of troubles with this method, proceed with manual tuning method.

==Manual tuning method==
Manual tuning of torque controller is some times done in order to optimize the torque controller response or to find the correct motor resistance [[MR]] and inductance [[ML]] parameters if unknown. Manual tuning also usually yields better torque response than the direct method which may help tuning of velocity or position tuning.
{{tip|If satisfactory performance was achieved by direct inductance & resistance setting method, you may skip the manual tuning method.}}
In order to change torque tuning, one needs to change motor resistance [[MR]] and inductance [[ML]] parameters until the torque response looks satisfactory.
===Preparations===
[[File:Torqgoodwithtestingtab.png|thumb|Correct torque tuning settings on the Testing tab.]]
Steps to do to begin torque tuning:
*Ensure that motor is [[Argon user guide/Drive parameterization|parameterized]] correctly and working 
*Fix the motor shaft so that it cannot rotate under full peak torque of the motor
*Make following parameter changes to Granity and click apply afterwards:
**Set drive in torque control mode [[CM]]
**Set torque bandwidth limit [[TBW]] to maximum 
**Choose ''Serial only'' setpoint input [[CM]]
**Untick Setpoint smoothing [[CIS]]
**Set Goals tab [[DIV]] and [[MUL]] to 50
**Make other necessary adjustments to have drive powered and enabled 
*Set-up the test stimulus and capture settings from Testing tab:
**Set target setpoint 1 [[TSP1]] to 5000-15000
**Set delay 1 [[TSD1]] to 0.05 seconds
**Set target setpoint 2 [[TSP2]] to 0
**Set delay1 [[STD2]] to 0.5 s
**Choose sample rate [[TSR]] of 10000 Hz or more
**Choose ''Capture setpoint change ind positive direction'' from the dropdown
**''Tick Continuously repeating capture''
**Tick ''Torque setpoint'' and ''Torque achieved'' from signals
**Tick ''Start capture'' to begin continous capture. 
**Tick Enable test stimulus [[TSE]] to begin a pulsed torque generation

Once the steps above are done, motor should be generating short torque pulses to a fixed shaft and torque response graphs should appear on the right side of Granity about once in 3-5 seconds.

===Adjusting MR and ML to for optimum torque control===

The task here is to adjust the [[MR]] and [[ML]] parameters to achieve near optimum step response for the torque controller. Observe the images below for guidance.

{{tip|If the drive faults during this testing due to overcurrent, try reducing [[TSP1]] value or increase fault current tolerance [[FOC]] parameter. Or try radically different [[MR]] and [[ML]] values. }}

[[File:TorqlowR.png|800px|]]

In this case the resistance [[MR]] value has been set too low causing slowly rising achieved torque curve. Such slow response would reduce servo responsiveness.

[[File:TorqhighR.png|800px|]]

In the opposite case (too high [[MR]] value) the response shows wavy oscillations and ovesrhoot.

[[File:TorqlowL.png|800px|]]

Same kind of phenomenon will be seen if motor inductance [[ML]] value is too low. Finding oscillation free tuning is finding the correct balance between the MR and ML as both affect each other.

[[File:TorqhigL.png|800px|]]

Too high inductance [[ML]] will cause sharp overshooting and high frequency oscillations. Motor may produce audible noise if oscillations are continuous (occurs with way too high ML).

[[File:Torqgood.png|800px|]]

The above image shows near optimum torque response with fast rising edge combined to minimal overshoot.

[[File:Torqgoodspinning.png|800px|]]

The above image shows what may happen if motor shaft is not fixed properly (allowed to rotate). This is with the same optimum settings like the previous image.

===Steps to do after manual tuning finished===
*Stop test stimulus by unticking [[TSE]]
*Stop scope catpure by unticking ''Continuously repeating capture''
*Undo all temporary changes made to settings (such as [[TBW]], [[CM]], [[DIV]], [[MUL]]) but leave the optimized [[MR]] and [[ML]] values active
*Save settings to drive memory by clicking ''Save settings on drive non-volatile memory'' button
==Using drive in torque mode==
If torque mode is the final desired operating mode, set-up the [[setpoint]] signal source from Granity Goals tab. Also see [[Signal path of motor drive]] for explanation of torque setpoint scale.
{{next|[[Tuning velocity controller]] - follow if drive will be used in velocity control mode|[[Tuning position controller]] - follow if drive will be used in position control mode }}