This project is the design for an autoclave control using Machinekit and a BeagleBone. It controls a heat element and a pressure relief valve using thermistors for input.
This repo is a rework of the Goldibox project repo.
The autoclave controller is a BeagleBone computer running Debian. It
senses temperatures through a pair of thermistors attachd to its
analog inputs, and it switches the heat element and pressure relief
valve through two solid-state relays (SSRs) connected through GPIO
digital output pins. See electronics/autoclave.fzz for connecting
them.
The Machinekit software runs the configuration in this
repository: some python user-space components in the bin/
directory, and HAL configuration in the hal/ directory. The
autoclave-control component decides whether to switch the relief
valve and burner on or off, depending on the program cycle and the
measured temperature. The autoclave-logger component logs to a RRD
database, from which time series charts are generated.
The autoclave-control component exposes a remote UI, used by the
MachinekitClient software, which can be downloaded for Android from
the Google Play store, and for Linux, Mac OS X and Windows directly
from the QtQuickVCP project. See the below screenshot. The
idle, boil, steam and heat stages in green are done. The current
stage is 15+ minutes into a 30 minute sterilization. That and the
blue-colored cool stage are not yet done. The button controls on the
left are enable/disable, start/stop, and a link to the graphs. The
indicators on the upper right are process elapsed time, burner duty
cycle, pressure and temperature.
The autoclave-logger component captures process data with
rrdtool and generates graphs like the one below, which
shows an entire cycle on a real machine. The autoclave was already
warmed up to 29.4 deg. from a previous run when the start button was
pressed shortly after 03:00. The water was heated to 100 degrees in
the boil stage, and the valve was opened (thick blue curve) for ten
minutes with the burner at 100% (yellow curve; 0% at 100, 100% at
110). Then the valve closed and the autoclave was heated to the 121
degree sterilization temperature. Pressure was also measured at 15
PSIG (solid orange curve). After 30 minutes, the burner was turned
off and the autoclave cooled to 32 degrees (not shown), and the cycle
was finished. After that, the autoclave switch back to idle mode at
20 degrees.
FIXME: configuration?
Follow the instructions at machinekit.io to download and install a mini-SD card image with Machinekit. Log into the BeagleBone.
On the BeagleBone, install the python-yaml package.
sudo apt-get install -y python-yaml
Clone this repository, and cd into the repository directory.
git clone https://github.com/zultron/autoclave_control
cd autoclave_control
On the BeagleBone, start the Autoclave control from the command line (load the overlay file for non-system installs):
# Install minimal apache and other config
sudo make install MININSTALL=1
# Start control
bin/autoclave -o
The Autoclave should now be ready for control. Start the MachinekitClient and open the Autoclave app.
Alternatively, run an Autoclave simulated control and GUI in a Docker container from the command line:
# Start the container
docker/qqvcp.sh
# Install minimal apache and other config
sudo make install MININSTALL=1
# Start control
bin/autoclave &
# Start GUI
MachinekitClient &
The Autoclave may be installed to the system so that it is run at every boot:
sudo make install
sudo systemctl daemon-reload
sudo systemctl enable autoclave
sudo systemctl start autoclave
The apache2 package must be installed and the web server running for
the time-series chart to work.
FIXME