Orbit does not work like in Inventor.
In Inventor there is an arc-ball that if clicked outside of exits the Orbit command.
or
In Inventor right click to Escape from Orbit command.
in Simulation I must have left hand free to hit the Esc key. This is inconvenient and doesn't follow convention of other programs.
Are you limited to a laptop with a touchpad? If you have a proper mouse with a middle mouse button, you can use the middle mouse button to rotate your model.
take a look at the following video: http://wikihelp.autodesk.com/Simulation_Mechanical/enu/2013/Help/0000-Essentia0/0001-General_1/0002-...
Alternatively, If you own a "3D connexion" 3D mouse you can use that to control your model.
Another option you have is to completely customize how your mouse behaves which is also highlighted in the above video.