Clover Core Libraries support for ROS2

This is a ROS2 port of the libraries written by CopterExpress for use with the Clover Drone Platform. In particular the following:

• The clover library from their clover project
• The ros_led project ros_led.
• The vl53l1x project vl53l1x_ros2

Installation

Local Development

Download the repository into your ros2 development workspace:

cd ~/dev_ws/src
git clone --recurse-submodules https://github.com/UoBFlightLab/clover_ros2_pkgs

Then build using colcon

cd ~/dev_ws/
colcon build
# Or specific packages using `colcon build --packages-select clover_ros2`

Docker

This project is also available as the starling-clover docker container for both amd64 and arm64 as part of Project Starling.

docker pull uobflightlabstarling/starling-clover:latest
docker run -it --rm --name clover --network=host uobflightlabstarling/starling-clover

This container also include mavros and will run starling-clover.launch.xml. It is recommended that you run with network=host to enable ROS2 communication.

See Project Starling for more details.

Running

Make sure the local setup is sourced: source install/setup.bash

Everything can be run with the following:

ros2 launch clover_ros2 clover.launch.xml

Packages

• clover_ros2: a selection of the core clover libraries ported to ROS2
• led_msgs: the led_msgs from ros_led ported to ROS2
• led_msgs_test: Python ROS2 testing for led_msgs from ros_led ported to ROS2
• ws281x: led drivers ros2 nodes from ros_led ported to ROS2
• ws281x_test test package for ws281x drivers
• vl53l1x_ros2 rangefinder driver ros2 nodes from vl53l1x_ros2. Note that this is a git submodule. See the README in the module itself for further details.

Clover ROS2

This is a port of some of the core source files of the clover packages. We only port the files which are relevant to the sensor. We do not need the control node as that is handled by mavros for us.

clover_led Node

This node controls higher level and more complex functionality of the led lights. It exposes the set_effect service which takes a clover setLEDEffect request message.

string effect
uint8 r
uint8 g
uint8 b
uint8 brightness
float32 duration
uint8 priority
bool base 
---
bool success
string message

where the effect parameter can be one of the following:

• fill: block fill colours
• blink: blink colour at a blink_rate parameter
• blink_fast: blink colour at a blink_fast_rate parameter
• fade: performs a fade from current colour to next colour at a fade_period parameter
• wipe: performs a wipe from current colour to next colour at a wipe_period parameter
• flash: flashes the colour flash_number amount of times with flash_period time inbetween. Then returns to previous effect if fill, fade or wipe
• rainbow_fill: fills the leds with rainbow
• rainbow: fills the led with rainbow
• reset: A special parameter which resets the base effect to the default.

The brightness parameter (0 - 255) details the overall brightness of the effect. Defaults to 255 if not specified.

The priority is an integer, by default, from 0 to 9 (set by parameter num_priority_levels). The controller implements a unique-priority priority queue like structure. That looks a bit like the following (truncated to 5 levels rather than the actual 9):

Priority:	0	1	2	3	4	5
Effect:	fill(100,100,100)				blink(255,0,0)

For each priority level, there is only one saved effect. Sending a second effect of the same priority level as previous will overwrite the previous effect. Each loop the controller will select and play the highest priority effect. If an effect has exceeded its duration it will be removed and the next highest selected.

The base parameter defines an effect as the base effect to be played if the queue is empty. This is useful for conveying a healthy connection or something similar. By default it is set as the rainbow effect. It can be reset by sending a SetLEDEffect request with effect=reset. Note if base is received the entire queue will be cleared.

The duration parameter is in seconds and details the length of time an effect should last. Not specifying this parameter, or setting to 0.0 gives indefinite duration to the effect. e

mavros_led node

This node is intended to be the drone watchdog node, monitoring the connection with mavros as well as other connections and conveying these states to the user through the LEDs.

It automatically attempts to subscribe to the mavros/state topic and sends LEDEffect requests based on the current state of the connection. The specific effects are given in the parameter file notify_params.yaml. The following are the key effects:

• no_mavros: The watchdog continuously monitors the connectiong with mavros. If there has been no message from mavros/state within a timeout period, the no_mavros effect is played. By default this is a blue quick blink with a short duration with priority 9.
• base: If a connection is found, the base effect is set as the base LED effect. By default this is set in the code to be a blue fill.
• emergency_stop_topic: If the emergency stop is triggered on /emergency_stop, this effect is triggered. By default is a red quick blink with a short duration with priority 9.
• armed: Plays when the vehicle changes from disarmed to arm for 2 seconds
• disarmed: Plays when vehicle changes from armed to disarm for 2 seconds
• manual
• posctl: Plays on position control mode
• offboard: Plays on offboard control mode

LED Control

Custom LED ROS messages (led_msgs package)

This is a port of the led_msgs ros1 package written by CopterExpress. See the original files here.

This is organised as an ament_cpp project so the python test file had to be moved to a separate ROS package.

Note: custom msg/srv/actions cannot currently be included in ament_python build project (13/05/2021)

WS281x LED Strip Support for ROS2 (ws281x package)

This is a port of the WS281x ROS1 package written by CopterExpress. See the original ros1 here

This is the LED strip used on the Clover Drone platform

This package contains the WS281x LED strip driver for ROS (on a rapsberry pi). Based on the rpi_ws281x library

Rangefinder

vl53l1x Rangefinder support for ROS2

This is STM VL53L1X time-of-flight rangefinder driver for ROS2. Tested on a Raspberry Pi 3 and 4 with CJMCU-531 board.

See the project here for more details. This is a ROS2 port of the original project here.

License

As per the original Clover source code, this ROS2 port is also covered under the MIT License.