The activity manager is the successor to smach_executer. Currently, it has rudimentary ability to run activities, and a query system which will be used to determine transitions in a state machine of activities. This README explains the basics of the query system.

Installation

The activity manager uses the PLY package to parse queries. First, install ply:

sudo apt-get install python-ply

Next build the activity manager:

rosmake activity_manager

Running

Launch the acitivity manager server:

roslaunch pr2_activities_launch activity_manager.launch

A simple query

Try asking the acitivity manager to evaluate a simple query about whether a given point is within a bounding box:

rosrun activity_manager query_client simple_within_bbox

The script outputs a JSON representation of the actionlib goal sent to the activity manager, and then the result of the query. As you can see, the query goal consists of 2 things:

• query - the query string. this looks like lisp.
• args - a list of argument bindings for the query string.

To keep things simple, there are only variable names in the query string itself; no literals. For this case, the query string looks like:

(point_within_bbox point bbox_origin bbox_size)

Each element of the args array specifies the name of one of the variables in the query string, and the value to assign to that variable as a JSON string.

More complex queries

Try running a slightly more complex query:

rosrun activity_manager query_client conjunction

This query returns true if the robot is currently charging and if a given point is within a bounding box. The query string is:

(and (is_charging) (point_within_bbox point bbox_origin bbox_size))

Here the function "and" is used with arguments which themselves are query functions. This ability to nest queries makes it possible to construct complex queries which can be stored as strings.

The "(is_charging)" function queries the current state of the robot. It returns a boolean. There are other queries which query the robot's state. For example, to find out the transform between two TF frames:

rosrun activity_manager query_client simple_get_transform

This runs the query:

(get_transform frame_a frame_b)

With frame_a set to "r_wrist_roll_link" and frame_b set to "base_link". The idea is that people can combine queries about transforms with queries about bounding boxes to find out if a certain part of the robot is in a specified area.

To see a list of the currently implemented functions and their argument types, run:

rosrun activity_manager list_query_functions