The code in this repository refers to the robot published by I-M-Robotics-Lab as 3-D model at makerworld for which code can be found at Ball-Balancing-Robot at GitHub
Since the Web UI in the original code included just the layout but no functionality, I developed a fully functional Web UI with client-server architecture.
Both, server (bb_robot_server.py) and client (bb_robot_client.py) can be run as services.
The solution is essentially based on the original code Ball-Balancing-Robot, where code from controller.py, robotKinematics.py, camera.py and PID.py were all integrated into the new bb_robot_server.py with a few architecture-related modifications.
See Demo Video.
Some parts of the original model have been modified.
See Modified Parts.
There, you will also find an updated parts- and shopping list
Before fixing the robot arms on the servos, it is necessary to bring these into a definite position.
After wiring the servos and setting up the Raspberry Pi, install the software.
Then connect to the server from a browser (See Usage).
With θ and φ set to 0, move the height (h) to the left which corresponds to the minimum height of the robot.
Then mount the robot arms so that the lower arms point slightly upwards with the screws connecting lower and upper arm being slightly below the plate holding the servos (base).
As camera, a Raspberry Pi Camera Module 3 Wide is recommended because this covers the entire top ring.
It is essential that servos and camera are correctly aligned
You can verify correctnes of servo numbers by using the calibration function.
See Installation of Ball-Balancing-Robot_CS
Connect to the client from any browser within the same network with
http://<server_name>:5000
The server initializes the robot from a configuration file bb_robot_config.json.
This file will be located in a config subdirectory of the active work directory, if this exists.
If not, a ~/bb_robot_home directory with a config subdirectory will be created at server start.
If a configuration file exists, contained data will be used for robot initialization.
If a configuration file does not exist at server start, it will be created with default values.
Example:
If the structural parameters ("configuration") for your robot differ from the defaults, you need to update these directly in the configuration file.
Especially, the length l1 of the upper arm should be verified.
Calibration parameters ("calibration") and some of the camera parameters (center, target, detection_radius) will be updated in the file when calibration is saved.
Modified PID parameters will be updated in the file when "Save & Reset" is pressed.
This function will also reset the PID controller.
By default, the server will start in "Manual" mode.
You can manually set "mode": "auto" in the configuration file to start in automatic mode.
When changing Mode in the dialog, the setting in the configuration file will not be changed.
Choose Mode "Calibration".
Udjust offsets (θ offs.) of the individual servos until the top panel is exactly horizontal.
The Detection Radius (D-rad) is the maximum radius within which the ball can be detected.
If the ball approches the top ring, contours of ball and top ring can no longer be destinguished.
You can activate Contours to see the effect.
In this case the ball position cannot be determined and the system assumes the last detected position.
In order to calibrate the Detection Radius, increase D-rad until the green circle tuches the top ring. You may need to udjust Center to center the circle.
Afterwards, reduce D-rad until the distance between the top ring and the green circle is at least the ball radius.
The Target is initially identical with Center.
You can modify it to choose a different target.
You can simulate the effect of different PID parameters on the resulting orientation of the top panel (θ, φ)
As input for training a Neural Network, PID results can be recorded by activating Rec when in Mode "Auto".
The number of records recorded so far is updated when the browser window is refreshed.
The resulting file is stored in the config folder.
Logging is initially set to ERROR logging.
A file handler is specified with the log file being located in the config folder.