[SalesForce] How to call a controller method from AngularJS

I'm loading the tree-view structure as shown below when the user clicks on the parent/child it spit on the console.log but i'm not sure how to pass the clicked parent/child node to apex controller

       $scope.my_tree_handler = function (branch) {
            console.log('you clicked on', branch);
            //how to pass the branch to controller ?????? 
        }

Screen shot:

This is the code:

<script>
    var myApp = angular.module('myApp', ['treeGrid']);

    // controller
    myApp.controller('treeGridController', function ($scope, $timeout) {
        var tree;
        var rawTreeData = {!JSONData};
        var myTreeData = getTree(rawTreeData, 'Id', '{!relationshipFieldName}');

        $scope.tree_data = myTreeData;
        $scope.my_tree = tree = {};
        $scope.expanding_property = {
            field: "Name",
            displayName: "Name",
            sortable : true,
            filterable: true
        };
        $scope.col_defs = {!FieldsJSON};
        $scope.my_tree_handler = function (branch) {
            console.log('you clicked on', branch);
            //how to pass the branch to controller ?????? 
        }
        //..........
</script>

I have read that you can use apex:actionFunction but in my situation I need to set the values user have clicked.

EDIT:
I have tried using javascript remoting function but getting the following error:

Visualforce Remoting Exception: Method 'mymethod' not found on
controller RN_sObjectHierarchy. Check spelling, method exists, and/or
method is RemoteAction annotated.

$scope.my_tree_handler = function (branch,scope) { 
                  Visualforce.remoting.Manager.invokeAction(
                   "RN_sObjectHierarchy.mymethod", branch.param,
                        function(result, event) {
                            if(result) {
                                scope.$apply(function(){
                                scope.result = result;

                                });
                                // something more to do?
                            } else {
                                console.log("There was an error");
                            } 
                        },
                   {escape: false} // No escaping, please
              );
        }

Controller:

@RemoteAction
public static void mymethod(String name){
    system.debug('///' +  name);
}