Setting up current and force control for Head Controller (HC) Versions C and D

1. Set up current control

1. Run CurrentPing.spt.
   • If the obtained bandwidth is acceptable, the script will ask whether or not it should save the focus parameters (the look up table with 'foc save lut' and the controller/estimator gains with 'foc save svf'). At the prompt, enter y or n.
   • If the obtained bandwidth is too low, an error window will pop up, and the parameters will not be saved. Contact a production engineer for further assistance.
2. Look at the FocCurVLPosn.ps graph. Ensure that the travel is smooth and the hysteresis is minimal.
3. Look at the LPosVLPos.ps graph. Ensure that there is no ringing in the response and that the travel is smooth.

Note: If you forgot to save the look up table and the SVF parameters, you can do so by entering foc save lut and foc save svf.

2. Set up force control

1. To set the actuator to force control mode, enter foc actmode 1 in the Splot terminal. If you want to change the start up actuator mode, then set the NVS value using set foc actmode.
2. To generate the lookup table for the force controller, enter foc gen fclut in the Splot terminal.
3. To save the lookup table to the NVS, enter foc save fclut in the Splot terminal.
4. Enter in the Splot terminal to set the verbosity level:vbs enable foc 3. Ensure that the verbose setting is never higher than 3 before running the next command, otherwise the wait will be long.
5. To automatically generate the effective gap table for the force controller, enter foc find gap in the Splot terminal. If this command has a hard time finding the gaps, then try changing the tfuture parameter with the foc tfuture or set foc tfuture commands. If the verbosity is 3, then the terminal output should contain a line stating values of ‘zeta’, which should be around 0.03 to 0.06:
   • If zeta is less than 0.02 just before this command failed, try increasing tfuture by 0.05ms.
   • If zeta is greater than 0.08 just before the command failed, try decreasing tfuture by 0.05ms.
   • tfuture tends to be between 0.25ms and 0.40ms. Once you find a value of tfuture that works, please update the NVS copy with set foc tfuture x, where x is the chosen value.
   • In some cases the message "Can't do a quadratic fit for lpos xxxx. Picked gap yyyy." may be displayed. It is acceptable if it appears only a couple of times. If the message appears four or more times, contact a production engineer for assistance.
6. To save the effective gap table to the NVS, enter foc save effgaplut in the Splot terminal.
7. Run ForcePing.spt.
   • If the obtainable bandwidth is high enough, the script will ask whether or not it should save the focus parameters (the controller/estimator gains with 'foc save fcsvf'). At the prompt, enter y or n.
   • If the obtained bandwidth is too low, an error window will pop up, and the parameters will not be saved. Contact a production engineer for further assistance.
8. Look at the FocCurVLPosn.ps graph. Ensure that the travel is smooth and the hysteresis is minimal.
9. Look at the LPosVLPos.ps graph. Ensure that there is no ringing in the response and that the travel is smooth.

Note: If you forgot to save the SVF parameters, you can do so by entering foc save fcsvf.

10. To set the default actuator mode to force control mode, enter set foc actmode 1 in the Splot terminal. This ensures that force control is the default actuator mode upon start up.
11. If required, enter >redirect disable in the Splot terminal.

If any of the scripts or commands fail, contact the Response Centre.