PF Manual Tuning

How to perform manual tunning on the PowerFoot

• Commands are case sensitive! Shift indicates an upper case command

1. Have user hold foot up in the air (level) before turning on PowerFoot
2. Initialize Telemetry
3. From wifi_fast.py command window, enter F4 to unlock screens
4. Check nominal (pyramid) torque setting:
   1. Have user hold foot up in the air (level)
   2. Go to sensors screen (enter 3)
   3. Enter Shift C to zero torque
   4. Note may need to zero torque after tuning due to drift.
5. Change virtual spring setpoint/offset
   1. Have user hold foot up in the air (level)
   2. s moves backwards (increases angle)
   3. x moves fwd (decreases angle)
   4. Check Matlab qIq screen to insure motor current is still near zero
   5. Have user lift heel and press toe, then hold foot in the air.
   6. Check Matlab qIq screen to insure motor current is still near zero
   7. Enter Shift Z to set the zero position
6. Go to std screen (enter "0")
7. Early stance adjustment (ES: in command window. Early_stance_impedance_k,b in exported parameters)
   1. Stiffness (Heel Strike)
      1. s increases stiffness, x decreases stiffness
   2. Damping
      1. Default setting works for most users
      2. d increases damping, c decreases damping
      3. Note If foot comes down too slow, increase damping ("foot flop")
8. Late Stance adjustment (LS: in command window. Late_stance_imp_k in exported parameters)
   1. Stiffness
      1. f increases, v decreases
      2. Note This is the K3 or "virtual spring". During dorsiflexion, loading spring. If "too light", or falling, make stiffer.
      3. Note Slow walking K needs to be more stiff, fast walking K needs to be less stiff
9. Set Peak Pyramid Torque Threshold (PCI: or power_curve_intercep in exported parameters)
   1. Shift R increases, Shift F decreases
   2. Have the user make some typical steps
   3. Set the PCI value equal or just below users typical torque value (on Matlab plots torque)
10. PFF Power Plantar Flexion (PFF: or pff_torque_gain in exported parameters)
    1. Shift I increases, Shift K decreases
    2. Watch Matlab tau pff screen
    3. Note Increases very quickly! Make small increases while walking
    4. Note Start at ~70, listen for regular motor activation
11. Turn on and adjust Spring Tail Setpoint (ENB:, TS_SP: )
    1. ? toggles on/off
    2. Adjust using > (more negative, more effect) or < (more positive, less effect)
    3. At slow speeds adjust till subject feels comfortable