The document proposes a live programming approach for the Robot Operating System (ROS) using PhaROS and LRP. It identifies limitations of ROS for live programming like static launch files and lack of hot code swapping. The approach integrates a domain specific language for hierarchical state machines called LRP with PhaROS, a ROS client for the Pharo programming language. This allows ROS nodes to be developed in Pharo and everything to happen at runtime, enabling live parameter changes, code updates, and connection changes for ROS applications. Examples of using this approach include a robot that stops on obstacles and an obstacle avoider behavior.

1. Towards
Live
Programming
in
ROS
with
PhaROS
and
LRP
Pablo
Estefó1,
Miguel
Campusano2,
Luc
Fabresse1,
Johan
Fabry2,
Jannik
Laval1,
and
Noury
Bouraqadi1
hJp://pleiad.cl
1
2
France
hJp://car.mines-­‐douai.fr

2. RoboOc
ApplicaOon
Lifecycle
1. Develop
/
Borrow
Parts
2. Assemble
Parts
3. Run
+
Analyze
Behavior
4. Stop
5. Fix
bugs
/
Improve
6. Goto
step
2
2

3. ROS
RoboOc
ApplicaOon
Lifecycle
1. Develop
/
Borrow
ROS
Packages
2. Assemble
=
Define
Launch
file
3. Run
+
Analyze
Behavior
4. Stop
5. Fix
bugs
/
Improve
6. Goto
step
2
3

4. ROS
RoboOc
ApplicaOon
Lifecycle
1. Develop
/
Borrow
ROS
Packages
2. Assemble
=
Define
Launch
file
3. Run
+
Analyze
Behavior
4. Stop
5. Fix
bugs
/
Improve
6. Goto
step
2
4
Context
is
lost
ForgoJen
details

5. Live
Programming
5
Edit
program
at
Run-­‐Ome
Immediate
Feedback

6. Programming
with
ROS
6
Parameters
Code
Node
1
Topic
Node
2

7. ROS
Example
7
square_length
Code
draw_
square
velocity
turtle

8. Requirements
for
Live
Programming
with
ROS
1. Stop/Start
=
Replace
individual
nodes
2. Change
parameters
at
run-­‐Ome
3. Change
code
at
run-­‐Ome
Parameters
4. Change
connecOons
=
topics
at
run-­‐Ome
8
Node
Topic
Code

9. Requirement
1
• Start/Stop
Start
=
Replace
individual
nodes
• Problem
in
ROS
:
– ApplicaOon
=
1
.launch
staOc
file
• Command
line
Changes
are
lost
– Bug
when
restarOng
individual
nodes
9
Node

10. Requirement
1
• Start/Stop
Start
=
Replace
individual
nodes
– Problem
in
ROS
:
• ApplicaOon
=
1
.launch
staOc
file
• Bug
when
restarOng
individual
nodes
– Example
restarOng
a
turtle
10
draw_
square
velocity
turtle

11. Requirement
2
• Change
node
parameters
at
run-­‐Ome
• Problem
in
ROS
:
– Parameters
fixed
in
launch
file/rosrun
command
line
– Changing
them
à
restart
the
full
app
11

12. Requirement
2
• Change
node
parameters
at
run-­‐Ome
• Problem
in
ROS
:
– Parameters
fixed
in
launch
file/rosrun
command
line
– Changing
them
à
restart
the
full
app
• Example
:
Change
square_length
12
draw_
square
velocity
turtle
square_length

13. Requirement
3
• Change
node
code
at
run-­‐Ome
• Problem
in
ROS
:
– Use
of
C/C++
mainly
– No
Hot
Code
Swapping
13
Code

14. Requirement
4
• Change
node
connecOons
at
run-­‐Ome
– Change
topics
names
(remape
/
name
space)
• Problem
in
ROS
:
– Topic
names
are
fixed
at
launch
Ome
14
Topic

15. Proposal
• Highly
reflecOve
and
Dynamic
– “Everything
happens
at
run-­‐Ome”
15

16. Proposal
• Highly
reflecOve
and
Dynamic
– “Everything
happens
at
run-­‐Ome”
• DSL
for
hierarchical
state
machines
– Integrated
with
Pharo
16

17. Proposal
• Highly
reflecOve
and
Dynamic
– “Everything
happens
at
run-­‐Ome”
• DSL
for
hierarchical
state
machines
– Integrated
with
Pharo
• PhaROS
:
ROS
Client
for
Pharo
– Nodes
developed
in
Pharo
17

18. LRP
+
PhaROS
in
AcOon
18
Laser
Range
Odometery
DifferenOal
Drive
/pose
LRP
Automata
PhaROS
node
ROS
Graph

19. Example
1:
Stop
on
Obstacle

20. 19
On
User
Command
On
Obstacle

21. Example
2:
Obstacle
Avoider

22. 20
Right
Obstacle
Obstacle
NO
Le2
Obstacle
NO
Obstacle
NO
Right
Obstacle
Le2
Obstacle