This repo provides code to stream IMU and GPS data over a websocket from the Sensor Server android app. It can be used in combination with our MinIO CSI server implementation to create a testbed for building-scale WiFi sensing applications.
This project directory consists of two nodes:
- gps_publisher.py: A ROS node that connects to a WebSocket server to receive GPS data and publish it as a ROS topic. It establishes a WebSocket connection to a specified URL (ws://localhost:8090/gps) and listens for incoming GPS data in JSON format, extracting latitude and longitude values. These values are then packaged into a NavSatFix message and published to the /gps ROS topic. The script also handles connection events, errors, and graceful shutdown on receiving a termination signal (Ctrl+C). Additionally, it periodically sends a "getLastKnownLocation" request to the WebSocket server to fetch the latest GPS coordinates.
- imu_publisher: A ROS node designed to collect and publish IMU (Inertial Measurement Unit) data from an Android device to a ROS topic. The script connects to a WebSocket server using a specified URL(ws://localhost:8090/sensors/connect?types={self.encoded_types}), retrieving accelerometer and gyroscope data. This data is buffered, synchronized based on timestamps, and then published as an Imu message to the /imu ROS topic. The node also handles errors, reconnection attempts, and shuts down gracefully when interrupted (Ctrl+C). The data synchronization ensures that the IMU data is aligned in time before being published.
In order to collect the accelerometer, gyroscope and GPS readings, we use an application called Sensor Server.
- There are various ways to retrieve the Inertial Measurement(IMU) and GPS readings and from the phone. However, the imu_publisher package achieves it by connecting the Android phone to the device via hotspot.
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To install this package, clone this repository in the catkin_ws directory and in the repository's root folder run catkin build:
cd /home/user/catkin_ws/src git clone https://github.com/WS-UB/imu_publisher.git cd imu_publisher catkin build -
Source the packages and confirm the paths are included:
source ./devel/setup.bash echo $ROS_PACKAGE_PATH -
Install the SensorServer application from Installation
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Once the application is downloaded, open it and click on the menu bar in the top left corner.
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Choose settings and enable the Use Hotspot Option.
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Go back to the Server in the bottom left corner and click on start.
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Set the
target_socketparameter ingps_publisher.launchandimu_publisher.launchto the websocket displayed by the app. -
If the connection is established, you will see a pop up notification on the application in the middle bottom at the Connections icon. Since we are retrieving the IMU data and GPS readings, we should be able to see two connections.
SensorServer Application: https://github.com/umer0586/SensorServer/blob/main/README.md