Expose deep learning models on a Coral usb accelerator via a Flask app. To run the app and expose over a network:
$ python3 coral-app.py
Then use curl to query:
curl -X POST -F image=@images/test-image3.jpg 'http://localhost:5000/v1/vision/detection'
{'predictions': [{'confidence': 0.953125,
'label': 'person',
'x_max': 918,
'x_min': 838,
'y_max': 407,
'y_min': 135},
{'confidence': 0.58203125,
'label': 'person',
'x_max': 350,
'x_min': 226,
'y_max': 374,
'y_min': 143}]
'success': True}
To see the help run:
$ python3 coral-app.py -h
See the coral-app-usage.ipynb Jupyter notebook for usage from python.
Install one of the disk images from edgetpu-platforms. In the /home/pi directory git clone this repository. You wil now have a file stucture like (pi3 &pi4 only, pi-zero differs):
$ ls
all_models coral-pi-rest-server edgetpu_api examples-camera project-posenet project-teachable simple-demo
Use the cd command to enter ~/simple-demo and test you installation:
pi@pi:~/simple-demo $ python3 classify_image.py --model /home/pi/all_models/mobilenet_v2_1.0_224_inat_bird_quant_edgetpu.tflite --label /home/pi/all_models/inat_bird_labels.txt --image parrot.jpg
INFO: Initialized TensorFlow Lite runtime.
---------------------------
Ara macao (Scarlet Macaw)
Score : 0.76171875
Assuming you saw the result above, use the cd command to enter ~/coral-pi-rest-server and (system wide, no viretual environment) install the required dependencies:
~/coral-pi-rest-server $ pip3 install -r requirements.txt
Now run the app:
~/coral-pi-rest-server $ python3 coral-app.py
You can run the app as a service. Edit coral.service file to fit your needs and copy into /etc/systemd/system as root using sudo cp coral.service /etc/systemd/system/coral.service. Once this has been copied, you can attempt to start the service using sudo systemctl start coral.service. See the status and logs with sudo systemctl status coral.service. Stop the service with sudo systemctl stop coral.service. You can have it start automatically on reboot by using sudo systemctl enable coral.service.
I am running a pi3 with the raspi camera below. FYI the camera is mounted on a pan-tilt stage.
Using the pi3 (which has only usb2) processing a single request from another machine via this server takes ~ 300 to 500 ms. Therefore this is certainly fast enough to process images at 1 FPS which in my experience is suitable for tasks such as counting people in a room.
The pi4 has USB3 so we would expect better speeds. However I get inference time consistently ~ 500 ms when querying from another machine. Therefore it appears the coral library does not yet take advantage of the USB3.
Pi zero disk image differs from the pi3 and pi4 images. To check your pi-zero disk image run:
~/simple-demo $ python3 classify_image.py \
--model models/mobilenet_v2_1.0_224_inat_bird_quant_edgetpu.tflite \
--label models/inat_bird_labels.txt \
--image parrot.jpg
---------------------------
Ara macao (Scarlet Macaw)
Score : 0.761719
To install flask I had to sudo pip3 install flask as attempts using requirements.txt kept timing out. Also since the directory structure is different on the pi-zero, in coral-app.py you need to edit:
MODELS_DIR = "/home/pi/simple-demo/models/"
I found that I get inference time in the range 2.5 to 5s when querying from another machine, so significantly slower than the pi3/pi4.
I recommend using a power supply which can supply 3 Amps, I use this one. Note that the official RPI supply delivers only 2.5 Amp and I found this was causing an issue where the stick would 'go to sleep' after a day of continual use.
If you have installed the raspberry pi disk images from edgetpu-platforms then you already have all the models in home/pi/all_models. If you are using a linux desktop you will need to download the models.
- The official pre-compiled models are at -> https://coral.withgoogle.com/models/
- It is also possible to train your own models -> try using Google Colaboratory as the free environment for training or -> https://cloud-annotations.github.io/training/object-detection/cli/index.html
The data returned by the app is as close as possible in format to that returned by Deepstack object detection endpoint, allowing you to use this app as the backend for HASS-Deepstack-object
Q: I get the error: HandleQueuedBulkIn transfer in failed. Not found: USB transfer error 5 [LibUsbDataInCallback]
A: I reflashed the SD card and tried again with success
- https://github.com/google-coral
- Using the official pi camera with Coral
- https://github.com/snmsung716/Following-camera-with-Coral-Accelerator-on-Raspberry-Pi
- https://github.com/lemariva/raspbian-EdgeTPU
- Pyimagesearch article on Coral
- Hands on with coral + docker
- Official Raspicam example
I forked the code in this excellent article -> https://blog.keras.io/building-a-simple-keras-deep-learning-rest-api.html code