Could not visualize the battery state topic using battery widget in Noetic

[amjack0]

Hi,

I am using the ROS Mobile to display the battery data on the android tablet. I am publishing the battery data on the battery topic /battery and I can see the topic is getting published. I can select my /battery topic from the battery widget as well.

But I am unable to see any data on battery GUI. And I get the following error.

[ERROR] [1655207807.911237185]: Client [/battery] wants topic /battery to have datatype/md5sum [sensor_msgs/BatteryState/476f837fa6771f6e16e3bf4ef96f8770], but our version has [sensor_msgs/BatteryState/4ddae7f048e32fda22cac764685e3974]. Dropping connection.

This is the code for publishing the battery data:

          ros::Publisher battery_pub = nh.advertise<sensor_msgs::BatteryState>("battery", 10);

          batt_msgs.header.stamp = ros::Time::now();
          batt_msgs.present = true;
          batt_msgs.percentage = percentage_cap;
          batt_msgs.voltage = voltage; 
          batt_msgs.current = current;
          batt_msgs.temperature = temperature;

          battery_pub.publish(batt_msgs);

Can anyone please tell me what can be missing here.

System: ROS Noetic + 20.04

@nicostudt

Danke ;)

[nicostudt]

Hey,
it might be possible that the message definitions of our app and your compiled ROS version are different. I'll take a close look and test it again.

[nicostudt]

We are eagerly waiting for an update of ROSjava to fix most of the problems here ... but unfortunately nothing happens for years.

[amjack0]

I tried to change the BatteryState.h message to fix the error (Although, not recommended but just for testing). The error got fixed, but ROS Mobile app got crashed.

[nicostudt]

Okay, I took a closer look on it.
We're currently depend on the message definitions of Melodic. In the BatteryState msg (Noetic) there is an additional field "temperature".

So there are several possibilities now:

1. We have to include a new feature, where you could choose the ROS version in the app. This would be a huge pain thinking about the current implementation of ROSjava.
2. You could change the message definition of BatteryState in Noetic to exclude "temperature".

[amjack0]

Yes, Thank you for your support.

I think, It's much better to go with 2nd option.
with second option do you mean, change the BatteryState.msg in /opt/ros/noetic or use a Custom msg based on BatteryState.msg without the temperature field.

[amjack0]

Hi,

So, I defined BatteryState.msg as a custom msg in my_package without the temperature field (as you recommended). All the errors are gone and the app is also running fine.

But I am again unable to see any data on battery GUI.

This is the code for publishing the battery data:

          #include <my_package/BatteryState.h>

          ros::Publisher battery_pub = nh.advertise<my_package::BatteryState>("battery", 10);
          my_package::BatteryState batt_msgs;


          batt_msgs.header.stamp = ros::Time::now();
          batt_msgs.present = true;
          batt_msgs.percentage = percentage_cap;
          batt_msgs.voltage = voltage; 
          batt_msgs.current = current;

          battery_pub.publish(batt_msgs);

This is the msg definition: msg file

@nicostudt

[nicostudt]

Mhh, do you use the Play Store version of the app or the custom build from this repo? My question would be if you have access to the logs and if there is an error issued.

[amjack0]

I'm using the play Store version of the app.

[amjack0]

So I tried to change the message definition of BatteryState in noetic to exclude the temperature field.
I used the rqt_graph to see the node communication. This is what I found,

1. When I use sensor_msgs/BatteryState to publish the /battery topic. The battery node created by ROS Mobile is communicating with the battery topic. But I don't see the data on GUI.

2. When I use my_package/BatteryState to publish the /battery topic. The battery node created by ROS Mobile is NOT communicating with the battery topic. And of course, I don't see the data on GUI.

have you tried the app with removing the temperature field withnoetic ?

[nicostudt]

I've found a discussion about the changed BatteryState Msg. Apparently it seems that you can republish the BatteryState in the old format, but I'll have to take another look at it.

[amjack0]

So, I tried the solution suggested in above discussion.
I wrote a node in between the GUI and BatteryState publisher, Which converts noetic msgs to melodic. It did not help either !
can you provide some help. I am out of options now ;(

[Chick92]

Having the same issue, any update on this?