Consider the inverted pendulum dynamics

m $$ $$ tanh

$$

$$ g

l sin $($$)+$ w $($t$)=$ u

where m in R$>0$ is the known pendulum inertia, in R$>0$ is the unknown constant coecient of

friction, g in R$>0$ is the known gravitational constant, l in R$>0$ is the known length of the pendulum,

and w : R $$ R is an unknown function that models the wind torque applied to the pendulum; the

function w can be bounded from above such tha