Introduction

This package is aimed at controlling the EEZYbotARM MK2 and implementing kinematic control of the robot. Implemented algorithms include forward kinematics, inverse kinematics, and a spline-based trajectory generator. Furthered, a controller node has been implemented to smoothly send commands to the servos using the gpiozero library. All of this has been implemented in ROS for easy usage.

Here's an example of a trajectory generation of a figure 8 (click on image to link to youtube)

This was all built on a raspberry pi running 64-bit Buster. Image can be found here.

Initial Setup

Install ROS

$ sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'
$ curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -
$ sudo apt update
$ sudo apt install ros-noetic-ros-core
$ echo "source /opt/ros/noetic/setup.bash" >> ~/.bashrc

Enable GPIO libraries

$ sudo systemctl enable pigpiod.service

Setup ROS

# Install necessary packages (if not already installed)
$ sudo apt install build-essential ros-noetic-rqt ros-noetic-rqt-graph --yes
# Create and build catkin workspace
$ mkdir -p ~/catkin_ws/src
$ cd catkin_ws/
$ catkin_make
$ source devel/setup.bash
# Clone this repo into the src directory
$ cd src/
$ git clone git@github.com:contagon/eezy_arm_ros.git

Build SciPy from source

# Install necessary libraries/packages
$ sudo apt-get install gcc g++ gfortran python3-dev libopenblas-dev liblapack-dev
$ pip3 install pybind11 cython pythran
# Download and build
$ cd ~/
$ git clone git@github.com:scipy/scipy.git
$ cd scipy/
$ git checkout v1.7.0 # If using Python 3.7
# Need to init submodules (particularly Boost)
$ git submodule update --init --recursive
$ python3 setup.py install --user   # Installs to your home directory
# Hang tight, it will be a while ;)

Usage

After running catkin_make and source devel/setup.bash, to launch all nodes, run

$ roslaunch eezy_arm_ros start.launch

Then, to send a desired position or joint angle, run one of the following commands

$ rostopic pub -1 /arm1/p_des geometry_msgs/Vector3 -- 200 -100 250
$ rostopic pub -1 /arm1/q_des eezy_arm_ros/Joints -- 0 0 0

There's a number of predefined trajectories you can send as well! Try either one of the following scripts

$ rosrun eezy_arm_ros run_axis.py y
$ rosrun eezy_arm_ros run_figure_eight.py

To speed up or slow it down, set the max_accel rosparam either in start.launch or via the command

$ rosparam set /arm1/max_accel 1000.0