“…and g i,ni (x) = g ni with g ni ̸ = 0 being a constant, whereas all the control direction functions g i,j (•), j = 1, 2, • • • , n i are allowed to be unknown in this paper. In addiction, more universalities on given system comparing with [34] and [36]: 1) just constrain |g i,j (•)| to have a lower bound; 2) the unknown nonlinear function f i,j (•) can be any smooth function, it does not require boundaries.…”