Specifications

33
AnyRevoluteJoint &Jnt = ..Jnts.Shoulder;
and
AnyRevoluteJoint &Jnt = ..Jnts.Elbow;
are the ones that affiliate the two drivers with the shoulder and elbow joints respectively. They are
constructed the same way as the joint definition in Lesson 3
in the sense that a local variable, Jnt, is
declared and can be used instead of the longer global name if we need to reference the joint somewhere
else inside the driver. Notice also the use of the reference operator '&' that causes the local variable to be a
pointer to the global one rather than a copy. It means that if some property of the globally defined joint
changes, then the local version changes with it.
The specifications of DriverPos and DriverVel are the starting value of the driver and the constant velocity,
respectively. Since these drivers drive angles, the units are radians and radians/sec.
Try loading the model again by hitting F7. If you did not mistype anything, you should get the message
"Loaded successfully" and no complaints about lacking kinematic constraints this time.
This is good news, because you are now actually ready to see the model move. If you look closer at the
pane in the bottom of the main frame, you will notice that it now contains the root of a tree in its upper left
cell. This is the place where the AnyBody system places your studies, and from this window you can execute
them, i.e., start analyses and calculations.