Servo Speed Control & Arduino ROS driver

This package contains a ROS-based firmware for microcontrollers and mulitple servo-motor open-loop speed control. The microcontroller script publishes the analog feedback (mV), subscribes to the goal angle topic and writes the PWM pulse to the servos. In the following video the goal is for each servo to achieve the same position but with different speeds.

servo_speed_control.mp4

Installation

Tested on:

1. Ubuntu 20.04 with ROS Noetic
2. Teensy 4.0

Install ROS serial for Noetic

$ sudo apt-get install ros-noetic-rosserial
$ sudo apt-get install ros-noetic-rosserial-arduino

Update System

$ sudo apt-get update

For teensy download the rules

Run:

$ wget https://www.pjrc.com/teensy/00-teensy.rules 
$ sudo cp 00-teensy.rules /etc/udev/rules.d/ 

Install Arduino IDE + Teensyrduino

Go to the folder scripts/shell_scripts that contains install_ros_arduino.sh

$ chmod +x install_ros_arduino.sh
$ ./install_ros_arduino.sh

Install rosserial using the arduino IDE

1. Open arduino IDE
2. Tools -> Manage Libraries
3. search rosserial and install

Test rosserial & teensyrduino installation

Open the "Blink" example from rosserial and upload the sketch example. Then:

$ roscore
$ rosrun rosserial_python serial_node.py /dev/ttyACM0
$ rostopic list 
$ rostopic pub /toggle_led std_msgs/Empty "{}"

If the state of the led changes, that means that you have successfully installed the rosserial package.

Make a workspace and get a copy of the repo

$ mkdir -p arduino_ws/src
$ cd ~/<your_workspace>/src
$ git clone https://github.com/MichaelMarav/ardui_ros.git
$ cd ../ && catkin_make

Build the custom rosmsgs

Source your ROS workspace:

$ source <workspace_name>/devel/setup.bash

Go to scripts/shell_scripts/ and run:

./build_rosmsgs.sh

If you don't want to do it automatically follow the tutorial below:

$ cd ~/Arduino/libraries
$ rosrun rosserial_client make_libraries .

This should create a "ros_lib/" folder

Now move to:

$ cd ~/Arduino/libraries/Rosserial_Arduino_Library/src
$ cp -r ~/Arduino/libraries/ros_lib/ardui_ros/ ./
$ rm -rf ~/Arduino/libraries/ros_lib/

In case any problems occurs, run this too and repeat the process:

$ rosrun rosserial_client make_library.py ~/Arduino/libraries <package_with_msgs>

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Usage

To initialize rosserial and the ardui-ros framework, run:

$ roslaunch ardui_driver ardui_driver.launch

This will initialize the servos at the angles specified at config/initial_state.yaml with the desired velocity.

You should see the /servo/JointStates topic with all the angles of the servos.

In order to command the servos to go anywhere you want with a specific velocity, modify servo_command.py and then run it:

$ rosrun ardui_driver servo_command.py