3D-printed robotic arm using Raspberry Pi, ROS, and Python. Based on Open Sourced LiteArm i2 Design.
The hardware for this robot consists of a 3D printed frame as well as a RaspberryPi with a custom "hat". The link to the frame design as well as details on the circuitry and bill of materials are below.
Based on Open Sourced LiteArm i2 Design. 3D printed.
Controller circuit to power/control the arm was built as a RaspberryPi Shield/Hat to consolidate hardware.
The table below contains the parts used to create the controller circuit. Additionally, red (5V), green (ground), and yellow (signals) solid core wire was used to make the connections.
| Part | Quantity | Link |
|---|---|---|
| Raspberry Pi | 1 | |
| Servos | 3 | |
| Perfboard (14x20) | 1 | |
| 11x1 Pin Male Headers | 1 | |
| 20x2 Pin Female Headers | 1 | |
| DC barrel jack | 1 | |
| Electrolytic Capacitor | 1 | |
| Capacitor | 1 | |
| Red LED | 1 | |
| 91ohm resistor | 1 | |
| Power Cable | 1 | |
| Ethernet Cable | 1 |
The controller circuit serves two main functions: 1) Power the motors and RaspberryPi off of a single 5V DC power supply (DC barrel jack + decoupling capacitors) and 2) breakout signals, power, and ground to header pins for the motors.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
|---|---|---|---|---|---|---|---|---|---|---|
| NC | NC | Ground | 5V | Signal-Wrist | Ground | 5V | Signal-Extension | Ground | 5V | Signal-Base |
- Servo Wrist: Connect to pins 3-5
- Servo Extension: Connect to pins 6-8
- Servo Base: Connect to pins 9-11
NOTE: Pins 1 and 2 are "Not Connected" and were added for future use to power/control an end effector such as an electromagnet.
| Column 1 | Column 2 |
|---|---|
| NC | 5V |
| NC | 5V |
| NC | NC |
| NC | NC |
| NC | Signal-Base (GPIO18) |
| NC | NC |
| NC | NC |
| NC | NC |
| NC | NC |
| NC | NC |
| NC | NC |
| Ground | NC |
| NC | NC |
| NC | NC |
| NC | NC |
| NC | Signal-Extension (GPIO13) |
| Signal-Wrist (GPIO12) | NC |
| NC | NC |
| Signal-LED | NC |
| Ground | NC |
The 20x2-pin female headers were placed on the underside of the perfoard to connect directly to the 20x2 set of male Raspberry Pi GPIO Pins.
NOTE: Position decoupling capacitors as close to 5V GPIO pins as possible.
The software for this robot was written in python for both the PC "command center" and the robot itself. All code is included in this single repository.
The following pin assignment was used for each servo (ensure the appropriate servo is connected to the right location on the 11x1 Male Header Connector.
| Device | GPIO Pin |
|---|---|
| Base | GPIO18 |
| Extension | GPIO13 |
| Wrist | GPIO12 |
| LED | GPIO26 |
This Robotic Arm uses Robotic Operating System (ROS) to transmit commands to the robot and also recieve live feedback on robot status and position.
A URDF file was constructed to visualize the geometry of the robot and create a simulated view for data replay and live visualization.
RQT with an RVIZ plugin can be used for data replay and live visualization. The runCC.sh script is configured to launch the RQT interface below with the perspective loaded.
To run this robot, you will need 4 terminals open on your PC. You will also need to connect your robot to power (5V) and ethernet to your PC.
Configure network settings on your PC so that you can communicate with your robot. You should be able to ping the IP address of your robot from your PC as well as SSH. Once SSH is open, you should be able to ping your PC from your robot SSH terminal.
Clone this repo on both the robot and host PC in a catkin workspace. run catkin_build to make this project on both the robot and PC.
Make sure devel/setup.bash is sourced in your terminals. This is typically done by adding this to your ~/.bashrc.
Configure ROS IPs and ROS MASTER URI on the Host PC and Raspberry Pi. The ROS MASTER URI should be set to the Host PC. For help, see this tutorial.
You will need 4 terminals open: 1) roscore, 2) SSH to robot + ./runRobot.sh, 3) ./runCC.sh 4) RQT
roscore
This project is setup such that the robot will attempt to connect to a rosserver running on the host PC. This can take some debugging. For help, see this tutorial.
ssh user@raspberrypi
cd path/to/this/repo
./runRobot.sh
This command will launch the robot software on the target hardware (raspberry pi). Note: this command may require root (sudo) privileges.
cd path/to/this/repo
./runCC.sh
This command will launch the Command Center Interface on the Host PC.
rqt --perspective-file RobotArmRQT.perspective
This command will launch a live visualization view to see ROS signals and a visualization of the robot in real time.