ROS-Adapter

Connecting the ROS of the Panda robot with the Panta Rhei Messaging System. This component subscribes to ROS topics and forwards selected metrics to the Panta Rhei messaging system which is based on Apache Kafka.

The metrics involve:

• Coordinates of the robot's working point
• Gripper finger width
• vertical force on the end effector

Therefore both services must be running:

• ROS
• panta-rhei stack

The ROS Adapter is based on the components:

• A ROS setup connected to the panda robot.
• Kafka Client librdkafka version 2.1
• Python Kafka module confluent-kafka-python version 0.11.6

Contents

1. Requirements
2. Basic Configuration
3. Quickstart

Requirements

1. Make sure the Panta Rhei stack is running. This ROS-Adaper requires Apache Kafka, as well as the SensorThings server GOST.

2. Make sure ROS runs and is accessable from the host machine:

   # cd /home/panda/franka_apps_ws/src/state_export/scripts/
   # ln -sf /home/panda/dtz_panda/ros_kafka_adapter/src/ros_kafka_adapter.py ros_kafka_adapter.py
   
   # cd /home/panda/franka_apps_ws
   # . devel/setup.bash
   roslaunch franka_control franka_control.launch robot_ip:=192.168.13.1
   rostopic list

   If connected with ssh ther will be shown an error message including pyqt, because there is not GUI. This message can be ignored. The command rostopic list should return multiple topics including /franka_state_controller/franka_states and /joint_states.

3. Install the Kafka libraries and clone the Panta Rhei client into the src-directory:

   sudo apt-get update && sudo apt-get install make
   # Installing librdkafka which is an C client library for Kafka
   mkdir /kafka  > /dev/null 2>&1 || true
   cd /kafka
   git clone https://github.com/edenhill/librdkafka
   cd librdkafka
   git checkout v0.11.1
   ./configure && make && sudo make install && sudo ldconfig
   
   # Installing official python client which is based on librdkafka
   pip install confluent-kafka

Basic Configuration

Now, the client can be imported and used in ros_kafka_adapter.py with:

```python
import os, sys
from client.digital_twin_client import DigitalTwinClient

# Set the configs, create a new Digital Twin Instance and register file structure
config = {"client_name": "ros-adapter",
          "system": "at.srfg.iot.dtz",
          "gost_servers": "192.168.48.71:8082",
          "kafka_bootstrap_servers": "192.168.48.71:9092,192.168.48.71:9093,192.168.48.71:9094"}
client = DigitalTwinClient(**config)
client.register(instance_file=INSTANCES)
```

Quickstart

The ROS-Adapter uses SensorThings to semantically augment the forwarded data. Data that is later on consumed by the suggested DB-Adapter decodes the generic data format using the same SensorThings server.

Starting franka control

Run in a separate console:

cd /home/panda/franka_apps_ws
roslaunch franka_control franka_control.launch robot_ip:=192.168.13.1

For information how to start the ROS demo, follow the internal link here.

Make sure rostopic echo /franka_state_controller/joint_states yields the joint states.

Setup of the ROS-Kafka-Adapter

This project is based on this repository. ROS-messages can only be forwarded into the Panta Rhei project if they are received as described above.

1. Clone the repository into /src/

   git clone --recurse-submodules https://github.com/iot-salzburg/ros_adapter.git

2. Create and activate virtualenv:

virtualenv --python=/usr/bin/python3.7 .venv
source .venv/bin/activate 
pip install -r requirements.txt

3. Run the script with:

/src/ros_adapter/.venv/bin/python3.7 /src/ros_adapter/src/ros_kafka_adapter.py

4. The auto-start script is in ~/.bashrc

/src/ros_adapter/.venv/bin/python3.7 /src/ros_adapter/src/ros_kafka_adapter.py $> /src/ros_adapter/ros_kafka_adapter.log &

It should start automatically.

5. Check if messages are received:

• In the Dashboard: http://192.168.48.71:3000/d/dtz-lab/dtz-dashboard?orgId=1&refresh=10s

• In Kafka (check for valid iot.ids:

  /kafka/bin/kafka-console-consumer.sh --bootstrap-server 192.168.48.71:9092 --topic at.srfg.iot.dtz.int
  

Deployment

4. The auto-start script is in ~/.bashrc

/src/ros_adapter/.venv/bin/python3.7 /src/ros_adapter/src/ros_kafka_adapter.py $> /src/ros_adapter/ros_kafka_adapter.log &

This launches the ROS-Adapter while booting, check using ps -ef |grep ros_kafka_adapter