YOLOV2 slow when Arduino serial comm inserted

Question

I have been working on object detection and tracking system for a while now. I have tried lighting up LEDs when a person is detected determining the coordinate of the bounding box based on the width of resolution range. As of now, the FPS was around 30 when I did not inserted serial comm functions. But when I have inserted the serial comms, then fps goes down way too low around 7-10. What could be causing the problem here?

OS = Windows

GPU = GTX 1070

CPU = i7

Model = Darkflow, yolov2

Code for object detection.

import cv2
from darkflow.net.build import TFNet
import numpy as np
import time
from collections import namedtuple
import luggage_arduino

"""
Main system for running the whole script for object detection and tracking
"""
class NeuralNetwork:
def __init__(self):
    """Define model configuration and weight"""
    options = {
        'model': 'cfg/yolov2.cfg',
        'load': 'bin/yolov2.weights',
        'threshold': 0.8,  # Sets the confidence level of detecting box, range from 0 to 1
        'gpu': 0.8  # If do not want to use gpu, set to 0
    }

    """Define OpenCV configuration"""
    tfnet = TFNet(options)
    colors = [tuple(255 * np.random.rand(3)) for _ in range(10)]  # Set colors for different boxes
    capture = cv2.VideoCapture(0, cv2.CAP_DSHOW)
    capture.set(cv2.CAP_PROP_FRAME_WIDTH, 1280)
    capture.set(cv2.CAP_PROP_FRAME_HEIGHT, 720)

    while True:  # Main loop for object detection and tracking
        stime = time.time()
        ret, frame = capture.read()
        box = cv2.rectangle(frame, (0, 0), (426, 720), (0, 0, 255), 2)  # Parameter of first segment (LEFT)
        box2 = cv2.rectangle(frame, (426, 0), (852, 720), (0, 0, 255), 2)  # Parameter of second segment (CENTER)
        box3 = cv2.rectangle(frame, (852, 0), (1280, 720), (0, 0, 255), 2)  # Parameter of third segment (RIGHT)
        if ret:
            results = tfnet.return_predict(frame)
            for color, result in zip(colors, results):
                tl = (result['topleft']['x'], result['topleft']['y'])
                br = (result['bottomright']['x'], result['bottomright']['y'])
                label = result['label']
                confidence = result['confidence']
                text = '{}: {:.0f}%'.format(label, confidence * 100)
                frame = cv2.rectangle(frame, tl, br, color, 5)
                frame = cv2.putText(frame, text, tl, cv2.FONT_HERSHEY_COMPLEX, 1, (0, 0, 0), 2)
                self.center_of_box(tl, br)  # Calls the function for coordinate calculation
            cv2.imshow('frame', frame)
            print('FPS {:.1f}'.format(1 / (time.time() - stime)))
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break

    capture.release()
    cv2.destroyAllWindows()

def center_of_box(self, tl, br):
    self.tl = tl
    self.br = br
    center_coord = namedtuple("center_coord", ['x', 'y'])  # List of calculated center coord for each FPS
    center_x = ((tl[0] + br[0]) / 2)
    center_y = ((tl[1] + br[1]) / 2)
    center_box = center_coord(center_x, center_y)  # Save center coord of detected box in list
    print(center_box)
    self.box_tracking(center_x)  # Call function for tracking the box coord

def box_tracking(self, center_x):
    self.center_x = center_x
    while True:
        if 0 <= center_x <= 426:
            center = -1
        elif 426 < center_x <= 852:
            center = 0
        elif 852 < center_x <= 1280:
            center = 1
        else:
            center = 2
        break
    luggage_arduino.Arduino(center)  # Calls function for serial comm

Code for pyserial comms:

import serial
import time

arduino = serial.Serial("com3", 9600)


def serial_comm():  # Pass the function
    pass


"""Main class for serial comm"""


class Arduino:
    def __init__(self, center):
        self.serial_comm(center)  # Calls function of serial comm

    def serial_comm(self, center):
        if center == -1:
            time.sleep(1)
            arduino.write(b'L')  # b can be replaced with str.encode("Your string here")
            serial_comm()
        elif center == 0:
            time.sleep(1)
            arduino.write(b'C')
            serial_comm()
        elif center == 1:
            time.sleep(1)
            arduino.write(b'R')
            serial_comm()
        else:
            center = 2
            time.sleep(1)
            arduino.write(b'N')
            serial_comm()
        time.sleep(2)

Answer 1

The calls to time.sleep() are probably the reason if your function is not running in a thread.

Is class Arduino used in a Thread? If not, it probably should.

When you are using Serial.readline(), these calls are blocking and waiting for data.

See section Speed Improvement in this answer and the code posted here.