1. Interactive Basic Tuning for the SERVOSTAR 300
Welcome to Danaher Motion’s first interactive tuning chart. The first three sheets of this document provide a flow chart to describe tuning the servo gains of a SERVOSTAR The remaining sheets give more detail.
After you start, click on the following icons:
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for extra detail
to return from “more…”
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Now, let’s get started…click here:
Next step

2. Resolver/Sine Encoder
Here is the velocity loop we will tune:
“Speed
Limit”
“Ramp Limit +”
“Ramp Limit -”
P-gain: “KP”
I-gain: “Tn”
BiQuad Filter
“LP Freq, HP Freq”
Limit
Ramp
Limit
PI+ +
Proportional
Integral (PI)
Filter
Current
Loop
Motor
Vel
Cmd _
Resolver/Sine Encoder
Conversion Filter
Filter constant:
(MRESBW)
Next step

3. After we tune the velocity loop, here is the position loop we will tune:
Gain:
“Ff factor” d dt
Feed-
forward
Gain: “KP” + + +
Velocity
Loop
Current
Loop
Motor
Proportional
Position
Generator _ _
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4. SERVOSTAR 300 Tuning STEP 1: Tune Proportional Gain
1a. Set up drive units.
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SERVOSTAR
300
Tuning
STEP 1:
Tune
Proportional
Gain
1b. Put drive in velocity mode.
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1c. Turn off filters and integrator.
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1d. Enable drive.
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1e. Command a square wave velocity.
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1f. Set up scope.
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1g. Tune KP.
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How is
it working?
Works well
Next step:
Tune Tn
Noise
problem
Resonance
Problem
Improve wiring
Increase resolution
Switch to sine encoder
1h. Noise Filters
Stiffen machine
Increase motor inertia
1i. Resonance Filters
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5. SERVOSTAR 300 Tuning STEP 2: Tune Integral Gain Prev step: Tune KP
2a. Raise Integral for 5-15% overshoot.
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Next step:
Tune Position
Loop

6. SERVOSTAR 300 Tuning STEP 3: Tune Position Loop Prev step: Tune Tn
3a. Set mode to position loop.
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3b. Set up Motion Tasks and Home drive.
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3c. Reconfigure Scope.
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3d. Set position loop gains low.
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3e. Set KP to maximum level without overshoot.
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3f. Add feed forward to improve response.
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Done! Click escape to end.

7. Step 1a
This section will give a simplified approach to setting units. The SERVOSTAR 300 has many variations of units; a few will be discussed.
Disable drive
Click on Basic Setup
Main “Tree”
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8. Select position units, normally deg, mm or “counts”
Step 1a
Select position units, normally deg, mm or “counts”
Tip: This selection only affects the display of parameters on screen. It has no effect on the operation of the drive.
Tip: Scale units so you will have necessary precision understanding that position entries do not support a decimal point.
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9. Step 1a
Select velocity units, normally RPM, or position units per minute or per second.
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10. Step 1a
Select accel units, normally ms -> VLIM, which means the time from 0 to VLIM.
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11. Enter the number of position units per rev
Step 1a
Click “Position Data”
Enter the number of position units per rev
Example: for degrees, enter 360.
Set system limits on accel, velocity, etc.
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12. Set OPMODE = “0: Digital Speed” Click Velocity loop from the Tree.
Step 1b
Set OPMODE = “0: Digital Speed”
Click Velocity loop from the Tree.
Start by tuning the velocity loop.
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13. Minimize filters: LP Freq = HP Freq = 1000 Zero integral (Tn = 0)
Step 1c
Minimize filters: LP Freq = HP Freq = 1000
Zero integral (Tn = 0)
Set KP very low (KP  0.01)
Check top speed.
Set accel times to 1ms
Tip: Turn off the filters for now…they will be used later if necessary.
Tip: Setting Tn=0 makes the system proportional control to simplify tuning. Vertical axes may drift if you zero the integral. If your load will fall when the integral is zeroed, do not zero Tn.
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14. Click Feedback from the Tree Set Feedback Bandwidth = 300 Hz
Step 1c
Click Feedback from the Tree
Set Feedback Bandwidth = 300 Hz
Set Acceleration Feedforward = 1
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15. Step 1d Enable drive Return...
Tip: The system has very low gain. Expect it to be soft. If the system oscillates or produces any unexpected movement, remove power.
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16. Set up Reversing Function for Square Wave
Step 1e
Set up Reversing Function for Square Wave
Click Oscilloscope on tree, then Motion Service tab
Click “Parameters…” button
Set up Reversing mode from 100 to 0 RPM
For high-friction systems, avoid zero speed
Set time for 500 msec at both speeds
Click OK to return to the scope screen
Tip: High inertia systems often often should be given just 25 or 50 RPM step commands. If you aren’t sure, just proceed and this will be corrected later.
Tip: For linear motion, make sure V1 = -V2.
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17. Start Motion Step 1f Click Motion Tab Select Reversing mode
Click Start
If no motion is apparent, the velocity (KP) gain is probably too low. Continue to the next step.
Step 1f
Tip: In high friction systems, the system may not move at all because of the low gain. If that’s the case, raise KP (on the Tuning screen) in increments of 50% until you see movement.
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18. Set up Scope Trigger Step 1f Click Trigger Tab
Trigger Position 25%, Trigger Level 1
Trigger Signal V_CMD
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19. Set up Scope Channels Step 1f Click Channels Tab
Select v_cmd, v_act, and I_act as shown.
Set Time/Div. To 20 ms
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20. Tune KP Step 1g Click the Tuning Tab; Click Record button.
Raise Velocity Loop KP to maximum value without overshoot
Ensure that the current does not saturate
Step 1g
Tip: When the integral is turned off, the speed will often not reach top speed because of friction. In the scope shot at right, this can be seen where velocity (green) is less than command (red).
Tips: A well tuned SERVOSTAR 300 driving a motor with a rigid load can respond to speed changes as fast as 2 ms without overshoot!
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21. Resolution noise (for Resolver/Sine Encoder only)
Step 1h
Resolution noise (for Resolver/Sine Encoder only)
If there is too much resolution noise, decrease feedback bandwidth (click “Feedback” on Tree to access).
Acceleration Feedforward (on Feedback screen) may have to be adjusted from the terminal screen, especially if bandwidth is below 200 Hz.
Tip: Resolution noise sounds much like static on the radio. It has no defined pitch.
Tip: Resolution noise is best solved by getting a more highly resolved feedback sensor. Consider switching to a sine encoder for the best resolution available.
Resolution noise produces noisy current and noisy velocity feedback
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22. Resolution noise Step 1h Adjusting Feedback Acceleration Feedforward
See Feedback Screen
Acceleration
Feedback
too large
Acceleration
Feedback
right
Tip: Feedback
Acceleration adjusts the S300 observer. Normally it is set to 1 and only changes when resolver bandwidth is lowered below 400 Hz.
Acceleration
Feedback
too small
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23. Two Types of Resonance Step 1i
Inertial-Reduction Instability emits an unpleasant, grinding, distorted tone. The Bode plot shows a broader frequency peak.
Tuned Resonance emits a pure tone, something like a tuning fork. The Bode plot shows a narrower frequency peak.
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Tuned Resonance
can be narrow
Bode plot of tuned resonance
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Bode plot of inertial-reduction instability

24. Inertial-Reduction Instability
Step 1i
Inertial-Reduction Instability
On Scope Screen, Tuning Tab
Set HP Freq >= 1000 Hz
Raise Velocity Loop KP as much as resonance allows
For more performance, try bi-quad filter
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Tip: Inertial-Reduction Instability is a problem best solved mechanically by stiffening the load, increasing the motor inertia, or reducing load inertia. Filtering techniques work, but they make it harder to get a responsive system.
Small amount of ringing is okay
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25. Inertial-Reduction Instability: Bi-Quad Filters
Step 1i
Inertial-Reduction Instability: Bi-Quad Filters
On Scope Screen, Tuning Tab
Reduce LP Freq from 1000 Freq in steps of 20%
Raise Velocity Loop KP as much as resonance allows
Continue process until little overshoot is present
Tip: With Inertial Reduction Instability, when you first reduce LP Freq, resonance normally worsens! Expect to reduce Kp. Below some frequency, LP Freq. will usually improve performance. However, in this example, the end performance is not clearly better than it was at the start.
Small amount of ringing is okay
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26. Tuned Resonance: Focused Bode
Step 1i
Tuned Resonance: Focused Bode
Click “Parameters…”
Narrow frequency band to 50 Hz and increase points to 50
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Open Loop: 10 dB in <25 Hz.
Tip: Tuned resonance often occurs above 500 Hz, the maximum frequency of the S600 Bode plot.
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27. Tuned Resonance: Resolver Bandwidth
Step 1i
Tuned Resonance: Resolver Bandwidth
From Feedback Screen, Feedback Bandwidth=200 Hz
Raise Velocity Loop KP as much as resonance allows
Use BiQuad Filters for more improvement.
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Tip: Tuned Resonance is a problem best solved mechanically by increasing the motor inertia, or reducing load inertia. Filtering techniques work, but they make it harder to get a responsive system.
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28. Tuned Resonance: Bi-Quad Filters
Step 1i
Tuned Resonance: Bi-Quad Filters
Set HP Freq well above resonant freq.
Reduce LP Freq while maximizing Kp.
Before Bi-Quad
After Bi-Quad
Reducing ringing
and faster response!
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29. Tune Tn Step 2a Start with Tn ~ 3 times the settling time of Step 1
Set Tn in “Speed” screen. Example, if settling time from Step one is 10 ms, start with Tn=30.
Lower Tn for 5% overshoot
Tip: Some systems don’t need any integral gain. Integral gain provides total elimination of error at when the system comes to rest. If you don’t need this, you may want to set Tn = 0 to simplify tuning.
Tip: The S300 auto scales so that velocity command and feedback may not be scaled the same.
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30. Set up for Position Loop
Step 3a
Set up for Position Loop
Disable drive
Set OPMODE = “8: Position Motion Tasks”
Click Motion Task Table button.
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31. Set up Motion Tasks Double click on “1” on left of Motion Task Table
Step 3b
Set up Motion Tasks
Double click on “1” on left of Motion Task Table
View Motion Task Table from main screen (see Step 3a)
Set up short move as shown below.
Rapid accel, but within ability of system
500 RPM top speed
Use REL ACT for simple moves.
Rapid decel
Next =1, repeats indefinitely
This move is short, just 35 degrees.
½ second between moves
Tip: Set up most aggressive move in application. If this works, the less aggressive moves should also work.
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32. Home system (required for tuning)
Select Home Screen
Enable drive
Select 0 “Set Reference Point immediately”
Click Start to home.
Step 3b
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33. Set up Scope Trigger Step 3c Set Trigger Edge Negative
Trigger Signal PSPEED
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34. Set up Scope Channels for Position Loop
Step 3c
Set up Scope Channels for Position Loop
Click Channels Tab
Select PSPEED, v_act, and I_act as shown.
Adjust Time/Div. as necessary (here 10 msec)
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35. Set Position Loop gain low
Start with Ff factor = 0
Set Position Loop KP = 0.01.
Step 3d
Gains are so low, peak speed is 62 RPM (500 RPM move)
Tips: When in positioning mode, V_CMD is an internal signal, so it’s best to turn it off as shown here. Use PSEPEED; ignore PSPEED units.
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Position loop gains active in OPMODE 8

36. Tune Position Loop gain
Start with Ff factor = 0
Raise KV in steps of 20% to maximum level without overshoot (from Position screen).
Step 3e
This bump is caused by Tn being too small.
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37. Tune Position Loop gain
Step 3e
Tune Position Loop gain
Continued…Eliminating the bump
To eliminate the bump, Increase Tn or Tn=0
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38. Adding Velocity Feed-forward
Step 3f
Adding Velocity Feed-forward
Set Ff factor = 0.5 or 0.6
If overshoot, reduce Position loop KP (typical 30%)
Tip: A mechanically rigid system can respond quickly. This unit responds in about 15 ms with conservative margins of stability.
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39. Adding Acceleration Feed-forward
Step 3e
Adding Acceleration Feed-forward
Restore Position KP to maximum value.
Set Ff factor to 0.8
Set Resolver Bandwidth to > 600 Hz.
Increase GPFFT to maximize performance.
Use terminal screen and start at GPFFT = 0.2

40. Saturation
Saturation occurs when the current command exceeds the peak capability of the drive. This distorts data and makes tuning more difficult. If your system saturates with a square wave command, reduce command amplitude. Watch for saturation at every step of tuning!
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