Navigation Stack performance

[Gonçalo Cabrita]

Hi everyone!

Here at the lab we use Roomba robots with Eee PCs on top. The Eee PCs have a
single core Intel Atom processor, not the quickest thing around! Each Roomba
is also equiped with an Hokuyo laser.

So I've recently been playing around with the ROS nav stack. I've tried to
make it as simple as possible according to the various tutorials and mailing
list msgs I've came across with, however I'm always getting a warning that
it is running below the 20Hz frequency. It is also noticeable the fact that
the robot does not move properly, and eventually crashes.

Previously I experimented the same setup on an Erratic robot with a Celeron,
and although it was taking pretty much all of the processor to run the nav
stack, it was able to move pretty well around the lab according to the
commands I was issuing from rviz.

So my question is, how can I use the nav stack in its simplest form, in
order to have it running smoothly on the Eee PCs?

I'm attaching the .yaml files I'm using for configuring the nav stack.

Thanks in advance!

Gonçalo Cabrita

[Eric Perko]

Gonçalo,

Could you try turning down the loop rates on things until the robot
can move safely? For example, you could reduce the loop rate by
changing the controller_frequency documented here:
http://www.ros.org/wiki/move_base . I've also seen CPU time free up by
turning down the update and publish frequencies of the costmaps. It
may also be useful to set the costmaps to the 2D grid vs. a voxel grid
(which I believe is the default). That parameter is documented here:
http://www.ros.org/wiki/costmap_2d#Map_type_parameters .

Basically, whenever I encountered a loop rate that was regularly
missing it's requested rate, I had to reduce the update frequency or,
in the case of the costmaps, size or resolution. I suggest reducing
loop rates until the warnings go away and checking to see if the
robots can still move safely in the environment with the slower update
rates.

Let us know how it goes - I'm interested in the parameters you end up
with and what performance you see on lower-end hardware.

- Eric

Post by Gonçalo Cabrita
Hi everyone!
Here at the lab we use Roomba robots with Eee PCs on top. The Eee PCs have a
single core Intel Atom processor, not the quickest thing around! Each Roomba
is also equiped with an Hokuyo laser.
So I've recently been playing around with the ROS nav stack. I've tried to
make it as simple as possible according to the various tutorials and mailing
list msgs I've came across with, however I'm always getting a warning that
it is running below the 20Hz frequency. It is also noticeable the fact that
the robot does not move properly, and eventually crashes.
Previously I experimented the same setup on an Erratic robot with a Celeron,
and although it was taking pretty much all of the processor to run the nav
stack, it was able to move pretty well around the lab according to the
commands I was issuing from rviz.
So my question is, how can I use the nav stack in its simplest form, in
order to have it running smoothly on the Eee PCs?
I'm attaching the .yaml files I'm using for configuring the nav stack.
Thanks in advance!
Gonçalo Cabrita
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

[Eitan Marder-Eppstein]

Goncalo,

There are a few basic things that you can do to help with performance:

1) You can increase the resolution of the costmaps. Since a Roomba is so
small, even 10cm resolution should probably be sufficient for navigation.
See the resolution parameter of the costmap:
http://www.ros.org/wiki/costmap_2d#Map_management_parameters

2) You can decrease the update rate of the costmaps from 5Hz to something
lower depending on your tolerance for seeing an obstacle. At 5Hz, it'll take
about 1/5th of a second to react to an obstacle, at 3Hz 1/3rd of a second,
etc. See the update_frequency parameter for the costmap:
http://www.ros.org/wiki/costmap_2d#Rate_parameters.

3) You can control the Roomba at a lower rate... maybe something like 10Hz
instead of 20Hz. For that you can set the controller_frequency parameter on
move_base: http://www.ros.org/wiki/move_base#Parameters.

Hope this helps,

Eitan

Post by Gonçalo Cabrita
Hi everyone!
Here at the lab we use Roomba robots with Eee PCs on top. The Eee PCs have
a single core Intel Atom processor, not the quickest thing around! Each
Roomba is also equiped with an Hokuyo laser.
So I've recently been playing around with the ROS nav stack. I've tried to
make it as simple as possible according to the various tutorials and mailing
list msgs I've came across with, however I'm always getting a warning that
it is running below the 20Hz frequency. It is also noticeable the fact that
the robot does not move properly, and eventually crashes.
Previously I experimented the same setup on an Erratic robot with a
Celeron, and although it was taking pretty much all of the processor to run
the nav stack, it was able to move pretty well around the lab according to
the commands I was issuing from rviz.
So my question is, how can I use the nav stack in its simplest form, in
order to have it running smoothly on the Eee PCs?
I'm attaching the .yaml files I'm using for configuring the nav stack.
Thanks in advance!
Gonçalo Cabrita
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

[Gonçalo Cabrita]

Thanks for your help on this matter Eitan and Eric!

I'll run a few experiments with various settings and report back the results soon.

Also on this subject, some of our Roombas are equipped with sonar arrays of 5 sonars arranged in

-PI/2 -PI/4 0 PI/4 PI/2

Do you think it would be a viable option to feed the sonar data into the nav stack in the form of a point cloud? Or is it not even worth trying as the amount of data produced is extremely small when compared to that of a laser range finder?

Thanks,

Gonçalo Cabrita
ISR - University of Coimbra
Portugal

Post by Eitan Marder-Eppstein
Goncalo,
1) You can increase the resolution of the costmaps. Since a Roomba is so small, even 10cm resolution should probably be sufficient for navigation. See the resolution parameter of the costmap: http://www.ros.org/wiki/costmap_2d#Map_management_parameters
2) You can decrease the update rate of the costmaps from 5Hz to something lower depending on your tolerance for seeing an obstacle. At 5Hz, it'll take about 1/5th of a second to react to an obstacle, at 3Hz 1/3rd of a second, etc. See the update_frequency parameter for the costmap: http://www.ros.org/wiki/costmap_2d#Rate_parameters.
3) You can control the Roomba at a lower rate... maybe something like 10Hz instead of 20Hz. For that you can set the controller_frequency parameter on move_base: http://www.ros.org/wiki/move_base#Parameters.
Hope this helps,
Eitan
Hi everyone!
Here at the lab we use Roomba robots with Eee PCs on top. The Eee PCs have a single core Intel Atom processor, not the quickest thing around! Each Roomba is also equiped with an Hokuyo laser.
So I've recently been playing around with the ROS nav stack. I've tried to make it as simple as possible according to the various tutorials and mailing list msgs I've came across with, however I'm always getting a warning that it is running below the 20Hz frequency. It is also noticeable the fact that the robot does not move properly, and eventually crashes.
Previously I experimented the same setup on an Erratic robot with a Celeron, and although it was taking pretty much all of the processor to run the nav stack, it was able to move pretty well around the lab according to the commands I was issuing from rviz.
So my question is, how can I use the nav stack in its simplest form, in order to have it running smoothly on the Eee PCs?
I'm attaching the .yaml files I'm using for configuring the nav stack.
Thanks in advance!
Gonçalo Cabrita
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

[Eric Perko]

Gonçalo,

I've done some work with sonars. The answer to your question is going to
depend on what exactly you want the sonars to do and their characteristics.
If you want precise navigation around obstacles in the world, sonars may be
a bit too fuzzy without some sort of probabilistic fusion in order to
pinpoint obstacles. If you just want close range obstacle detectors, they
definitely can help there.

The largest challenge we (mobilerobots.case.edu) had with sonars was
twofold:

1. They can mark a lot of the space we want to traverse at longer ranges
(3-4 meters) with a 20-30 degree beam angle
2. LIDAR and SONAR may not agree and so marking and clearing got
complicated.

The first was improved by switching to sonars with narrower beam widths
and/or not using the sonar out to its max distance. The second is actually
the main reason we cared about sonar - while they aren't as precise as a
laser, they can detect glass, black objects and objects outside the
horizontal plane of our laser scanner. This makes them ideal close range
obstacle detectors to prevent the robot damaging anything or injuring
someone.

In order to overcome the marking/clearing thing, I ended up feeding in both
the LIDAR and sonar as LaserScan messages (quicker than doing PointClouds
myself) at different z heights. By setting the min and max heights for each
sensor, I was able to get the voxel grid costmap to essentially maintain a
LIDAR layer and a sonar layer. Because it does a 2D projection for the
planner, this worked nicely for my use case. Definitely a bit hacky
though...

- Eric

Post by Gonçalo Cabrita
Thanks for your help on this matter Eitan and Eric!
I'll run a few experiments with various settings and report back the

results

Post by Gonçalo Cabrita
soon.
Also on this subject, some of our Roombas are equipped with sonar arrays

of

Post by Gonçalo Cabrita
5 sonars arranged in
-PI/2 -PI/4 0 PI/4 PI/2
Do you think it would be a viable option to feed the sonar data into the

nav

Post by Gonçalo Cabrita
stack in the form of a point cloud? Or is it not even worth trying as the
amount of data produced is extremely small when compared to that of a

laser

Post by Gonçalo Cabrita
range finder?
Thanks,
Gonçalo Cabrita
ISR - University of Coimbra
Portugal
Goncalo,
1) You can increase the resolution of the costmaps. Since a Roomba is so
small, even 10cm resolution should probably be sufficient for navigation.
http://www.ros.org/wiki/costmap_2d#Map_management_parameters
2) You can decrease the update rate of the costmaps from 5Hz to something
lower depending on your tolerance for seeing an obstacle. At 5Hz, it'll take
about 1/5th of a second to react to an obstacle, at 3Hz 1/3rd of a second,
http://www.ros.org/wiki/costmap_2d#Rate_parameters.
3) You can control the Roomba at a lower rate... maybe something like 10Hz
instead of 20Hz. For that you can set the controller_frequency parameter on
move_base: http://www.ros.org/wiki/move_base#Parameters.
Hope this helps,
Eitan

Post by Gonçalo Cabrita
Hi everyone!
Here at the lab we use Roomba robots with Eee PCs on top. The Eee PCs have
a single core Intel Atom processor, not the quickest thing around! Each
Roomba is also equiped with an Hokuyo laser.
So I've recently been playing around with the ROS nav stack. I've tried to
make it as simple as possible according to the various tutorials and mailing
list msgs I've came across with, however I'm always getting a warning that
it is running below the 20Hz frequency. It is also noticeable the fact that
the robot does not move properly, and eventually crashes.
Previously I experimented the same setup on an Erratic robot with a
Celeron, and although it was taking pretty much all of the processor to run
the nav stack, it was able to move pretty well around the lab according to
the commands I was issuing from rviz.
So my question is, how can I use the nav stack in its simplest form, in
order to have it running smoothly on the Eee PCs?
I'm attaching the .yaml files I'm using for configuring the nav stack.
Thanks in advance!
Gonçalo Cabrita
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

[Gonçalo Cabrita]

Hi guys!

I've been experimenting with the nav stack on the Roomba and this is what
I've come up with:

I found out that the controller_frequency parameter was the one that had the
bigger impact on processor time when made smaller. I experimented with 10Hz
and then 5Hz and everything works fine.

I also reduced the update frequency of both the local and global costmaps to
3Hz, but ended up bringing them back to 5Hz has I did not notice much
difference.

I also played around with the maps sizes and resolution, however with a
resolution of 0.1 the robot is not able to go through tighter spaces, so I'm
back at 0.05 resolution.

To sum up the nav stack was not running at 20Hz controller_frequency,
however now that it is at 10Hz or 5Hz it always works, even when I push it
on the rest of the parameters.

There is only one issue. Sometimes the robot goes into a wall, and when it
is too close, it backs up, and then it tries to go against the wall again,
only to back up once more, and it just stays there going back and forth.
Could that be related to the low controller_frequency?

Next I will turn the laser off and connect the sonars (outputting data as
point cloud) to see what happens.

Gonçalo Cabrita
ISR - University of Coimbra
Portugal

Post by Eric Perko
Gonçalo,
I've done some work with sonars. The answer to your question is going to
depend on what exactly you want the sonars to do and their characteristics.
If you want precise navigation around obstacles in the world, sonars may be
a bit too fuzzy without some sort of probabilistic fusion in order to
pinpoint obstacles. If you just want close range obstacle detectors, they
definitely can help there.
The largest challenge we (mobilerobots.case.edu) had with sonars was
1. They can mark a lot of the space we want to traverse at longer
ranges (3-4 meters) with a 20-30 degree beam angle
2. LIDAR and SONAR may not agree and so marking and clearing got
complicated.
The first was improved by switching to sonars with narrower beam widths
and/or not using the sonar out to its max distance. The second is actually
the main reason we cared about sonar - while they aren't as precise as a
laser, they can detect glass, black objects and objects outside the
horizontal plane of our laser scanner. This makes them ideal close range
obstacle detectors to prevent the robot damaging anything or injuring
someone.
In order to overcome the marking/clearing thing, I ended up feeding in both
the LIDAR and sonar as LaserScan messages (quicker than doing PointClouds
myself) at different z heights. By setting the min and max heights for each
sensor, I was able to get the voxel grid costmap to essentially maintain a
LIDAR layer and a sonar layer. Because it does a 2D projection for the
planner, this worked nicely for my use case. Definitely a bit hacky
though...
- Eric

Post by Gonçalo Cabrita
Thanks for your help on this matter Eitan and Eric!
I'll run a few experiments with various settings and report back the

results

Post by Gonçalo Cabrita
soon.
Also on this subject, some of our Roombas are equipped with sonar arrays

of

Post by Gonçalo Cabrita
5 sonars arranged in
-PI/2 -PI/4 0 PI/4 PI/2
Do you think it would be a viable option to feed the sonar data into the

nav

Post by Gonçalo Cabrita
stack in the form of a point cloud? Or is it not even worth trying as the
amount of data produced is extremely small when compared to that of a

laser

Post by Gonçalo Cabrita
range finder?
Thanks,
Gonçalo Cabrita
ISR - University of Coimbra
Portugal
Goncalo,
1) You can increase the resolution of the costmaps. Since a Roomba is so
small, even 10cm resolution should probably be sufficient for navigation.
http://www.ros.org/wiki/costmap_2d#Map_management_parameters
2) You can decrease the update rate of the costmaps from 5Hz to something
lower depending on your tolerance for seeing an obstacle. At 5Hz, it'll

take

Post by Gonçalo Cabrita
about 1/5th of a second to react to an obstacle, at 3Hz 1/3rd of a

second,

Post by Gonçalo Cabrita
http://www.ros.org/wiki/costmap_2d#Rate_parameters.
3) You can control the Roomba at a lower rate... maybe something like

10Hz

Post by Gonçalo Cabrita
instead of 20Hz. For that you can set the controller_frequency parameter

on

Post by Gonçalo Cabrita
move_base: http://www.ros.org/wiki/move_base#Parameters.
Hope this helps,
Eitan

Post by Gonçalo Cabrita
Hi everyone!
Here at the lab we use Roomba robots with Eee PCs on top. The Eee PCs

have

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
a single core Intel Atom processor, not the quickest thing around! Each
Roomba is also equiped with an Hokuyo laser.
So I've recently been playing around with the ROS nav stack. I've tried

to

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
make it as simple as possible according to the various tutorials and

mailing

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
list msgs I've came across with, however I'm always getting a warning

that

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
it is running below the 20Hz frequency. It is also noticeable the fact

that

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
the robot does not move properly, and eventually crashes.
Previously I experimented the same setup on an Erratic robot with a
Celeron, and although it was taking pretty much all of the processor to

run

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
the nav stack, it was able to move pretty well around the lab according

to

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
the commands I was issuing from rviz.
So my question is, how can I use the nav stack in its simplest form, in
order to have it running smoothly on the Eee PCs?
I'm attaching the .yaml files I'm using for configuring the nav stack.
Thanks in advance!
Gonçalo Cabrita
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

[Eric Perko]

Gonçalo,

Glad you were able to get the nav stack functioning on the EEE PCs.

For the problem backing into a wall, can you display the paths in RVIZ along
with the costmaps? Some details here:
http://www.ros.org/wiki/navigation/Tutorials/Using%20rviz%20with%20the%20Navigation%20Stack

I'm wondering if, for some reason, the global planner is just not planning
around the wall - that could cause the sort of repetitive behavior you are
seeing. If the plan output by the global planner is actually good looking,
then there are other problems to deal with.

- Eric

Post by Gonçalo Cabrita
Hi guys!
I've been experimenting with the nav stack on the Roomba and this is what
I found out that the controller_frequency parameter was the one that had
the bigger impact on processor time when made smaller. I experimented with
10Hz and then 5Hz and everything works fine.
I also reduced the update frequency of both the local and global costmaps
to 3Hz, but ended up bringing them back to 5Hz has I did not notice much
difference.
I also played around with the maps sizes and resolution, however with a
resolution of 0.1 the robot is not able to go through tighter spaces, so I'm
back at 0.05 resolution.
To sum up the nav stack was not running at 20Hz controller_frequency,
however now that it is at 10Hz or 5Hz it always works, even when I push it
on the rest of the parameters.
There is only one issue. Sometimes the robot goes into a wall, and when it
is too close, it backs up, and then it tries to go against the wall again,
only to back up once more, and it just stays there going back and forth.
Could that be related to the low controller_frequency?
Next I will turn the laser off and connect the sonars (outputting data as
point cloud) to see what happens.
Gonçalo Cabrita
ISR - University of Coimbra
Portugal

Post by Eric Perko
Gonçalo,
I've done some work with sonars. The answer to your question is going to
depend on what exactly you want the sonars to do and their characteristics.
If you want precise navigation around obstacles in the world, sonars may be
a bit too fuzzy without some sort of probabilistic fusion in order to
pinpoint obstacles. If you just want close range obstacle detectors, they
definitely can help there.
The largest challenge we (mobilerobots.case.edu) had with sonars was
1. They can mark a lot of the space we want to traverse at longer
ranges (3-4 meters) with a 20-30 degree beam angle
2. LIDAR and SONAR may not agree and so marking and clearing got
complicated.
The first was improved by switching to sonars with narrower beam widths
and/or not using the sonar out to its max distance. The second is actually
the main reason we cared about sonar - while they aren't as precise as a
laser, they can detect glass, black objects and objects outside the
horizontal plane of our laser scanner. This makes them ideal close range
obstacle detectors to prevent the robot damaging anything or injuring
someone.
In order to overcome the marking/clearing thing, I ended up feeding in
both the LIDAR and sonar as LaserScan messages (quicker than doing
PointClouds myself) at different z heights. By setting the min and max
heights for each sensor, I was able to get the voxel grid costmap to
essentially maintain a LIDAR layer and a sonar layer. Because it does a 2D
projection for the planner, this worked nicely for my use case. Definitely a
bit hacky though...
- Eric

Post by Gonçalo Cabrita
Thanks for your help on this matter Eitan and Eric!
I'll run a few experiments with various settings and report back the

results

Post by Gonçalo Cabrita
soon.
Also on this subject, some of our Roombas are equipped with sonar arrays

of

Post by Gonçalo Cabrita
5 sonars arranged in
-PI/2 -PI/4 0 PI/4 PI/2
Do you think it would be a viable option to feed the sonar data into the

nav

Post by Gonçalo Cabrita
stack in the form of a point cloud? Or is it not even worth trying as

the

Post by Gonçalo Cabrita
amount of data produced is extremely small when compared to that of a

laser

Post by Gonçalo Cabrita
range finder?
Thanks,
Gonçalo Cabrita
ISR - University of Coimbra
Portugal
Goncalo,
1) You can increase the resolution of the costmaps. Since a Roomba is so
small, even 10cm resolution should probably be sufficient for

navigation.

Post by Gonçalo Cabrita
http://www.ros.org/wiki/costmap_2d#Map_management_parameters
2) You can decrease the update rate of the costmaps from 5Hz to

something

Post by Gonçalo Cabrita
lower depending on your tolerance for seeing an obstacle. At 5Hz, it'll

take

Post by Gonçalo Cabrita
about 1/5th of a second to react to an obstacle, at 3Hz 1/3rd of a

second,

Post by Gonçalo Cabrita
http://www.ros.org/wiki/costmap_2d#Rate_parameters.
3) You can control the Roomba at a lower rate... maybe something like

10Hz

Post by Gonçalo Cabrita
instead of 20Hz. For that you can set the controller_frequency parameter

on

Post by Gonçalo Cabrita
move_base: http://www.ros.org/wiki/move_base#Parameters.
Hope this helps,
Eitan

Post by Gonçalo Cabrita
Hi everyone!
Here at the lab we use Roomba robots with Eee PCs on top. The Eee PCs

have

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
a single core Intel Atom processor, not the quickest thing around! Each
Roomba is also equiped with an Hokuyo laser.
So I've recently been playing around with the ROS nav stack. I've tried

to

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
make it as simple as possible according to the various tutorials and

mailing

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
list msgs I've came across with, however I'm always getting a warning

that

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
it is running below the 20Hz frequency. It is also noticeable the fact

that

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
the robot does not move properly, and eventually crashes.
Previously I experimented the same setup on an Erratic robot with a
Celeron, and although it was taking pretty much all of the processor to

run

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
the nav stack, it was able to move pretty well around the lab according

to

Post by Gonçalo Cabrita

Post by Gonçalo Cabrita
the commands I was issuing from rviz.
So my question is, how can I use the nav stack in its simplest form, in
order to have it running smoothly on the Eee PCs?
I'm attaching the .yaml files I'm using for configuring the nav stack.
Thanks in advance!
Gonçalo Cabrita
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users
_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users

_______________________________________________
ros-users mailing list
https://code.ros.org/mailman/listinfo/ros-users