• About

• Usage

• Messages

• Topics

• Service Files

• Services

• Setup

• Development

About

- ROS Package Names:
  - weigher
  - weigher_interfaces
- ROS Distribution: humble
- Description: This repository contains ROS 2 packages that publish weight messages from a digital scale.
- Version: 1.0.0
- Weigher Package: weigher
- Weigher Node Name: weigher
- Weigher Launch File: weigher_launch.py
- Weigher Messages:
  - Weight.msg
  - WeightArray.msg
- Weigher Topics:
  - /weigher/weight
  - /weigher/weight_thresholded
  - /weigher/weight_array
  - /weigher/weight_array_thresholded
- Weigher Service Files:
  - Tare.srv
- Weigher Services:
  - /weigher/tare
- Docker Image Name: weigher:humble
- Release Date: 2023-02-16
- Creation Date: 2022-12-14
- License: BSD-3-Clause
- URL: https://github.com/RatCity-Habitat/weigher_ros
- Author: Peter Polidoro
- Email: [email protected]
- Copyright: 2023 Howard Hughes Medical Institute
- References:
  - https://github.com/janelia-pypi/loadstar_sensors_interface_python
- Python Dependency List: loadstar_sensors_interface

Usage

Publisher

• Connect weigh scale to Raspberry Pi USB port.
• Connect Raspberry Pi to power and Ethernet.

Scale will be tared on power up and automatically begin publishing weight messages.

Subscriber

On a computer connected to the same network as the Raspberry Pi, either use Docker or install ROS 2 to subscribe to weight messages.

Docker

docker run -it --net=host --pid=host weigher:humble ros2 topic list
docker run -it --net=host --pid=host weigher:humble ros2 topic echo /weigher/weight
docker run -it --net=host --pid=host weigher:humble ros2 topic echo /weigher/weight_thresholded
docker run -it --net=host --pid=host weigher:humble ros2 topic echo /weigher/weight_array
docker run -it --net=host --pid=host weigher:humble ros2 topic echo /weigher/weight_array_thresholded

ROS 2 on Ubuntu

source ~/ros2_ws/install/setup.bash
ros2 topic list
ros2 topic echo /weigher/weight
ros2 topic echo /weigher/weight_thresholded
ros2 topic echo /weigher/weight_array
ros2 topic echo /weigher/weight_array_thresholded

Services

On a computer connected to the same network as the Raspberry Pi, either use Docker or install ROS 2 to use weigher services.

Docker

docker run -it --net=host --pid=host weigher:humble ros2 service list
docker run -it --net=host --pid=host weigher:humble ros2 service call /weigher/tare weigher_interfaces/srv/Tare

ROS 2 on Ubuntu

source ~/ros2_ws/install/setup.bash
ros2 service list
ros2 service call /weigher/tare weigher_interfaces/srv/Tare

Connect to Raspberry Pi for development and monitoring

SSH into Raspberry Pi

ssh [email protected]

Web Console

https://weigher.lan:9090/

• username: weigher
• password:

Messages

Weight.msg

# This file is generated automatically from metadata
# File edits may be overwritten!

# Single weight reading.
builtin_interfaces/Time stamp
float64 weight # Measurement of the Weight in grams.

WeightArray.msg

# This file is generated automatically from metadata
# File edits may be overwritten!

# Multiple weight readings.
Weight[] array

Topics

weight

Send all messages from the digital scale one at a time along with a timestamp for that measurement.

$ ros2 topic echo /weigher/weight
---
stamp:
  sec: 1676470173
  nanosec: 765260627
weight: 0.13607771100000002
---
stamp:
  sec: 1676470173
  nanosec: 883177140
weight: 0.0
---
stamp:
  sec: 1676470174
  nanosec: 11527425
weight: 0.04535923700000001
---
stamp:
  sec: 1676470174
  nanosec: 176475007
weight: 0.18143694800000004
---

$ ros2 topic hz /weigher/weight
average rate: 574.719
        min: 0.000s max: 0.038s std dev: 0.00568s window: 2338
average rate: 576.536
        min: 0.000s max: 0.038s std dev: 0.00566s window: 2922

weight_thresholded

Send some messages from the digital scale one at a time along with a timestamp for that measurement, if the weight value exceeds a threshold. The threshold value is set with the threshold parameter.

$ ros2 topic echo /weigher/weight_thresholded
---
stamp:
  sec: 1676470255
  nanosec: 932870887
weight: 520.8601184710001
---
stamp:
  sec: 1676470256
  nanosec: 19947998
weight: 504.39471544000014
---
stamp:
  sec: 1676470256
  nanosec: 161346684
weight: 499.8134325030001
---
stamp:
  sec: 1676470256
  nanosec: 301352968
weight: 498.5887331040001
---

$ ros2 topic hz /weigher/weight_thresholded
average rate: 503.230
        min: 0.000s max: 0.054s std dev: 0.00695s window: 5102
average rate: 503.906
        min: 0.000s max: 0.054s std dev: 0.00697s window: 5613

weight_array

Send an array of Weight messages to increase the size and decrease the frequency of messages published on this topic. The maximum array length is set by the weight_array_length_max parameter.

$ ros2 topic echo /weigher/weight_array
---
array:
- stamp:
    sec: 1676473446
    nanosec: 920160731
  weight: 2.0411656650000003
- stamp:
    sec: 1676473446
    nanosec: 921633371
  weight: 2.0411656650000003
- stamp:
    sec: 1676473446
    nanosec: 922349652
  weight: 2.0865249020000003
- stamp:
    sec: 1676473446
    nanosec: 922925743
  weight: 2.0865249020000003
- '...'
---

$ ros2 topic hz /weigher/weight_array
average rate: 0.287
        min: 3.460s max: 3.495s std dev: 0.01312s window: 4
average rate: 0.288
        min: 3.454s max: 3.495s std dev: 0.01571s window: 5

weight_array_thresholded

Send an array of Weight messages to increase the size and decrease the frequency of messages published on this topic. The maximum array length is set by the weight_array_length_max parameter.

Only include weight messages in the array if the weight value exceeds a threshold. The threshold value is set with the threshold parameter.

Do not send empty arrays.

$ ros2 topic echo /weigher/weight_array_thresholded
---
array:
- stamp:
    sec: 1676473988
    nanosec: 201336549
  weight: 491.467332895
- stamp:
    sec: 1676473988
    nanosec: 202358047
  weight: 491.467332895
- stamp:
    sec: 1676473988
    nanosec: 203483274
  weight: 491.467332895
- stamp:
    sec: 1676473988
    nanosec: 204520182
  weight: 491.467332895
- '...'
---

$ ros2 topic hz /weigher/weight_array_thresholded
average rate: 0.251
        min: 3.933s max: 4.048s std dev: 0.04806s window: 4
average rate: 0.251
        min: 3.933s max: 4.048s std dev: 0.04406s window: 5

Service Files

Tare.srv

# This file is generated automatically from metadata
# File edits may be overwritten!

---
builtin_interfaces/Time stamp
bool success

Services

tare

$ ros2 service call /weigher/tare weigher_interfaces/srv/Tare
requester: making request: weigher_interfaces.srv.Tare_Request()

response:
weigher_interfaces.srv.Tare_Response(stamp=builtin_interfaces.msg.Time(sec=1676492636, nanosec=617772030), success=True)

Setup

Subscriber

Docker

1. Install Docker

   https://docs.docker.com/engine/install/ubuntu/#install-using-the-repository

2. Clone this repository

   git clone https://github.com/RatCity-Habitat/weigher_ros.git

3. Make Docker image

   cd weigher_ros
   docker build -f .metadata/docker/Dockerfile -t weigher:humble .
   # or
   make -f .metadata/Makefile docker-image

ROS 2 on Ubuntu

1. Install ROS 2

   https://docs.ros.org/en/humble/Installation/Ubuntu-Install-Debians.html
   

2. Create ROS 2 Workspace and clone this repository

   mkdir -p ~/ros2_ws/src && \
   cd ~/ros2_ws/src && \
   git clone https://github.com/RatCity-Habitat/weigher_ros.git

3. Setup Python virtualenv

   sudo apt install python3-venv
   cd ~/ros2_ws
   make -f src/weigher_ros/.metadata/Makefile virtualenv

4. Build ROS packages

   1. Source the ROS underlay and activate the Python virtualenv and build ROS packages

      # build may finish with stderr warnings about deprecated setup.py install
      # if using Python 3.10 or higher
      cd ~/ros2_ws && \
      make -f src/weigher_ros/.metadata/Makefile ros-build

Publisher

Raspberry Pi

1. Setup Raspberry Pi

   https://github.com/janelia-experimental-technology/raspberrypi_setup

   • username: weigher
   • hostname: weigher

2. SSH into Raspberry Pi

   ssh [email protected]

3. Web Console

   https://weigher.lan:9090/

4. Clone Repository

   cd ~ && \
   git clone [email protected]:RatCity-Habitat/weigher_ros.git

5. Add deploy ssh key to Github Repository

   cat .ssh/id_ed25519.pub

6. Install make for metadata commands

   sudo apt install make

7. Docker image

   cd ~/weigher_ros && \
   make -f .metadata/Makefile docker-image

8. Pi Setup

   cd ~/weigher_ros && \
   make -f .metadata/Makefile pi-setup
   sudo reboot

9. Check docker and systemd service

   systemctl status docker
   systemctl status [email protected]
   systemd-analyze plot > boot_analysis.svg
   docker container list

Development

Docker

Run Docker container

make -f .metadata/Makefile docker-container

Run Docker container with serial port access

make -f .metadata/Makefile docker-container-port

Run Docker container and start publishing weight messages

make -f .metadata/Makefile docker-publish-weight

Run Docker container and echo weight messages

make -f .metadata/Makefile docker-echo-weight-array
make -f .metadata/Makefile docker-echo-weight-array-thresholded

Run Docker container and tare scale

make -f .metadata/Makefile docker-tare

Stop all Docker containers

docker stop $(docker ps -aq)

Find running container Name

docker ps

Run bash commands in running container

docker exec -it container-name bash

Ubuntu

Build

1. Source the ROS underlay and activate the Python virtualenv and build ROS packages

   # build may finish with stderr warnings about deprecated setup.py install
   # if using Python 3.10 or higher
   cd ~/ros2_ws && \
   make -f src/weigher_ros/.metadata/Makefile ros-build

Run

1. Source the ROS underlay and overlay and activate Python virtualenv and run the weigher node

   1. Launch file

      source ~/ros2_ws/src/weigher_ros/.metadata/setup.bash && \
      source ~/ros2_ws/install/setup.bash && \
      ros2 launch weigher weigher_launch.py

   2. ROS Run

      source ~/ros2_ws/src/weigher_ros/.metadata/setup.bash && \
      source ~/ros2_ws/install/setup.bash && \
      ros2 run weigher weigher

2. Echo the weigher topics

   # Open a new termial
   source ~/ros2_ws/install/setup.bash
   ros2 topic echo /weigher/weight
   ros2 topic echo /weigher/weight_thresholded
   ros2 topic echo /weigher/weight_array
   ros2 topic echo /weigher/weight_array_thresholded

Raspberry Pi

Update

cd ~/weigher_ros
git pull
make -f .metadata/Makefile docker-image
make -f .metadata/Makefile pi-setup
sudo reboot

Metadata

Install Guix

Install Guix

Clone Repository

git clone [email protected]:RatCity-Habitat/weigher_ros.git

Edit metadata.org

make -f .metadata/Makefile metadata-edits

Tangle metadata.org

make -f .metadata/Makefile metadata