
Opening the ‘‘cart model’’ subsystem reveals the blocks shown in Figure 5.68. Note that the
‘‘Display option’’ of the ‘‘Mux’’ parameter blocks is set to ‘‘signals’’ in order to identify its
inputs. The parameters of the two ‘‘Fcn ’’ blocks are expressions relating the accelerations ‘‘xdd’’
and ‘‘thetadd’’ to the inputs ‘‘x,’’ ‘‘xd,’’ ‘‘u,’’ ‘‘thetad,’’ and ‘‘theta’’ (from the ‘‘mux’’
block). The ‘‘Fcn’’ block input notation is u[1], u[2], ...,u[5] where u[1] is the first input
‘‘x,’’ u[2] is ‘‘xd,’’ and so forth.
From Equ ation 5.65, the ‘‘Fcn’’ block parameter expression for ‘‘xdd’’ is
(m*l*u[4]
^
2*sin(u[5])–m*g*cos(u[5])*sin(u[5])þu[3])=
(Mþm*sin(u[5]) ...