step down distance for floor sticking (default [0, -0.5, 0])
cos angle for forward contact detection (default cos(75°) ≈ 0.259)
minimum forward movement for stair detection (default 0.02)
extra step down after stair walk (default [0, 0, 0])
test distance for floor validation (default 0.15)
step up distance for stair walking (default [0, 0.4, 0])
Settings for update() with stair walking and floor sticking.