Default Kp=28.5 generates only ~4 Nm at 8° error, insufficient to
overcome gravity on the upper body. Bump to Kp=100, Kd=5 (matching
hip-level stiffness) so the waist motor actually drives to the
commanded position. Motor effort limit is 25 Nm, so 14 Nm command
at 8° error is well within range.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>