$controller service is responsible for instantiating controllers.
It's just a simple call to $injector, but extracted into a service, so that one can override this service with BC version.
$controller(constructor, locals);
| Param | Type | Details | 
|---|---|---|
| constructor | function()string | 
         If called with a function then it's considered to be the controller constructor function. Otherwise it's considered to be a string which is used to retrieve the controller constructor using the following steps: 
  | 
    
| locals | Object | 
         Injection locals for Controller.  | 
    
| Object | Instance of given controller.  |