The model has three segments:

Segment $1$: The leg $($from knee to ankle$)$

Segment $2$: The thigh $($from hip to knee$)$

Segment $3$ : The trunk $($from hip to head$)$

Each segment is connected through frictionless revolute joints, and you may assume that the foot is rigidly connected to the ground.

For each of the segments $($leg$,$ thigh, and trunk$),$ the following information is given:

$m_1,m_2,m_3$ : Mass of each segment in kilograms

$J_1,J_2,J_3$ : Moment of inertia of each segment with respect to its center of mass in $kg*m^2$

$l_1,l_2,l_3$ : Distance from the connection point to the center of mass of each segment

$g=9\mathrm{.}81\frac{m}{s^2}$ : Gravitational acceleration.

Tasks:

A$.$ Draw the free$-$body diagram.

B$.$ Formulate the Newton$-$Euler equations for each of the segments.