Problem of access to the data of /ekf_nav

[mohand150]

Hello,
currently I work with an Ellipse2-A, I use sbg_driver on ROS to retrieve the data
in my project, I need 3 data:
[roll, pitch, yaw] (in rad) -> found on the topic /ekf_euleur
velocity (in m / s ^ 2) -> found on the topic imu_data/accel & imu_data/gero
speed (in m / s) -> /mag
I have a question, I found that according to the name of the topic /ekf_euleur, this data comes out of the kelman filter
but the topicsimu_data/accel & imu_data/gero & /mag are there the output of the kelman filter? or are the raw data of the sensors?
Does the Ellipse2-A model have velocity data coming out of the EKF? the topic /ekf_nav does not receive any data
if yes, how to get them?
thanks for any help :)

[ErwanCL]

Hello,

the topicsimu_data/accel & imu_data/gero & /mag are there the output of the kelman filter? or are the raw data of the sensors?

These data are directly the data measured by the sensors.

the topic /ekf_nav does not receive any data, if yes, how to get them?

You can receive data from the Ellispe. You just have to change the configuration file that you're using, and set the corresponding parameters. By default, it is set to 0 (disabled), you can change it according to the frequency output you want (Frequency is defined in the config file).

# Position and velocities in NED coordinates with the accuracies on each axis
log_ekf_nav: 0

[mohand150]

thank you for your reply

By default, it is set to 0 (disabled), you can change it according to the frequency output you want (Frequency is defined in the config file).

for the parameter log_ekf_nav I already modify it in the parameters to receive the data at 25 Hz before posting this problem but I do not receive any data on this topic

Q1- Does the ellipseA model generate postion and velocities via the EKF? by subscribing to this topic ... I receive no data

1. I need these 3 data:
   1- angular position - vector3- (in radian)
   2- linear speed - vector3- (in m / s)
   3- linear acceleration - vector3- (in m / s ^ 2)
   4- angular velocity - vector3- (rad / s)

2. angular position I get it on the topic /ekf_euleur,I always need the linear speed (m/s), linear acceleration (m/s2) and angular velocity (rad/s).

Q2- Is there a topic that publishes these data coming out of EKF?

Q3- is the data of: imu_data / accel (m / s ^ 2) and imu_data / gero (rad / s)
are enough accurate for use on a drone or it will be necessary to pass them in a kelman filter before?

cordially

[ErwanCL]

Q1- Does the ellipseA model generate postion and velocities via the EKF? by subscribing to this topic ... I receive no data

The EllipseA does NOT generate position and velocities via EKF, navigation is not enabled on this product.
https://www.sbg-systems.com/wp-content/uploads/Ellipse_Series_Leaflet.pdf

Q2- Is there a topic that publishes these data coming out of EKF?

There is one, ekf_nav topic, but you won't be able to use it with your EllipseA.

Q3- is the data of: imu_data / accel (m / s ^ 2) and imu_data / gero (rad / s)
are enough accurate for use on a drone or it will be necessary to pass them in a kelman filter before?

It depends on which data you need and how you use it. But sensors data at high frequency are pretty accurate, so you can use it for data coupling with other sources (like GPS) if you want to have accurate positioning.

[mohand150]

Thank you