PF Manual Tuning

How to perform manual tunning on the PowerFoot

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

1. Initialize Telemetry
2. From wifi_fast.py command window, enter F4 to unlock screens
3. 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.
4. If foot is not level, 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. Enter Shift Z to set the zero position
5. Go to std screen (enter "0")
6. 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. d increases damping, c decreases damping
      2. Note If foot comes down too slow, increase damping ("foot flop")
7. 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
8. 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 to the users typical torque value (on Matlab plots torque)
9. 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