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i. Project Introduction
"The 'AutonomiX Innovators' project showcases a scaled autonomous vehicle utilizing real-time image processing and proportional-derivative control for lane maintenance and traffic cue adherence. The project is based on raja_961's Instructable 'Autonomous Lane-Keeping Car Using Raspberry Pi and OpenCV' (https://www.instructables.com/Autonomous-Lane-Keeping-Car-Using-Raspberry-Pi-and/) and prior ELEC 424 contributions, particularly 'There Are Four of Us' project (https://www.hackster.io/there-are-four-of-us/autonomous-rc-car-d71671).
ii. Tuning PID Controllers
We adjusted the camera to a resolution of 160x120, which achieves the right balance between clear visuals and fast processing. For controlling how sharply the car steers, we set the kp value at 0.095 and the kd value at 0.0095. These settings help the car to steer correctly by responding to the error in its course, which were determined through trial and adjustments.
iii. Handling Stop Boxes
Our approach to stop box detection utilizes hue-based filters within OpenCV, informed by the foundational code from Team 'ReaLly BaD Idea'. The detection mechanism triggers a stop action, with subsequent resumption of movement fine-tuned to avoid premature retriggering.
iv. PD Plot
The PD plot—a graphical representation mapping the vehicle's error, proportional response, and derivative response across sequential frames—provides a visual exposition of the vehicle's real-time path correction dynamics. This plot manifests the vehicle's ability to self-correct its trajectory, minimizing lateral deviation from the demarcated lane, as governed by the control logic codified in our 'main.py'.
vi. Speed and Steering Voltage Plot
The accompanying graph illustrates the vehicle's steering and speed voltage profiles over a trial run. A discernible reduction in speed occurs at stop signals, while steering voltage oscillations reflect the course's geometrical demands. Notably, the steering voltage shows a predominance of lower values toward the end of the track, correlating with the continuous left turn, indicative of the control system's adaptation to sustained d"The vehicle's hardware, detailed in an image within the attachments, includes a Raspberry Pi microcontroller and essential sensor arrays. Our vehicle's stability throughout the course is ensured by the strategic placement of the camera and secure mounting of components."irectional change.
v. Vehicle Hardware
The vehicle's hardware, detailed in an image within the attachments, includes a Raspberry Pi microcontroller and essential sensor arrays.
vi. Vehicle in Action
Below is a video example of how our project works in practice.
import cv2
import numpy as np
import math
import sys
import time
import RPi.GPIO as GPIO
import board
import busio
import adafruit_mcp4728
import matplotlib.pyplot as plt
import csv
i2c = busio.I2C(board.SCL, board.SDA)
mcp4728 = adafruit_mcp4728.MCP4728(i2c, 0x64)
#channel b is steering, channel a is power
#int(65535/4) should be straight for steering
# GPIO.setwarnings(False)
#throttle
# throttlePin = 25 # Physical pin 22
# in3 = 23 # physical Pin 16
# in4 = 24 # physical Pin 18
#additional throttle value??
#Steering
# steeringPin = 22 # Physical Pin 15
# in1 = 17 # Physical Pin 11
# in2 = 27 # Physical Pin 13
# GPIO.setmode(GPIO.BCM)
# GPIO.setup(in1,GPIO.OUT)
# GPIO.setup(in2,GPIO.OUT)
# GPIO.setup(in3,GPIO.OUT)
# GPIO.setup(in4,GPIO.OUT)
# GPIO.setup(throttlePin,GPIO.OUT)
# GPIO.setup(steeringPin,GPIO.OUT)
go_faster_tick_delay = 80
go_faster_tick = 0
current_speed = int(65535/2)
# Steering
# in1 = 1 and in2 = 0 -> Left
# GPIO.output(in1,GPIO.LOW)
# GPIO.output(in2,GPIO.LOW)
# steering = GPIO.PWM(steeringPin,1000)
# steering.stop()
# Throttle
# in3 = 1 and in4 = 0 -> Forward
# GPIO.output(in3,GPIO.HIGH)
# GPIO.output(in4,GPIO.LOW)
# throttle = GPIO.PWM(throttlePin,1000)
# throttle.stop()
#the value to speed up/ slow down
def getRedFloorBoundaries():
"""
Gets the hsv boundaries and success boundaries indicating if the floor is red
:return: [[lower color and success boundaries for red floor], [upper color and success boundaries for red floor]]
"""
return getBoundaries("redboundaries.txt")
def getBoundaries(filename):
"""
Reads the boundaries from the file filename
Format:
[0] lower: [H, S, V, lower percentage for classification of success]
[1] upper: [H, S, V, upper percentage for classification of success]
:param filename: file containing boundary information as above
:return: [[lower color and success boundaries], [upper color and success boundaries]]
"""
default_lower_percent = 50
default_upper_percent = 100
with open(filename, "r") as f:
boundaries = f.readlines()
lower_data = [val for val in boundaries[0].split(",")]
upper_data = [val for val in boundaries[1].split(",")]
if len(lower_data) >= 4:
lower_percent = float(lower_data[3])
else:
lower_percent = default_lower_percent
if len(upper_data) >= 4:
upper_percent = float(upper_data[3])
else:
upper_percent = default_upper_percent
lower = [int(x) for x in lower_data[:3]]
upper = [int(x) for x in upper_data[:3]]
boundaries = [lower, upper]
percentages = [lower_percent, upper_percent]
return boundaries, percentages
def isMostlyColor(image, boundaries):
"""
Detects whether or not the majority of a color on the screen is a particular color
:param image:
:param boundaries: [[color boundaries], [success boundaries]]
:return: boolean if image satisfies provided boundaries, and an image used for debugging
"""
#Convert to HSV color space
hsv_img = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)
#parse out the color boundaries and the success boundaries
color_boundaries = boundaries[0]
percentage = boundaries[1]
lower = np.array(color_boundaries[0])
upper = np.array(color_boundaries[1])
mask = cv2.inRange(hsv_img, lower, upper)
output = cv2.bitwise_and(hsv_img, hsv_img, mask=mask)
#Calculate what percentage of image falls between color boundaries
percentage_detected = np.count_nonzero(mask) * 100 / np.size(mask)
# print("percentage_detected " + str(percentage_detected) + " lower " + str(lower) + " upper " + str(upper))
# If the percentage percentage_detected is betweeen the success boundaries, we return true, otherwise false for result
result = percentage[0] < percentage_detected <= percentage[1]
if result:
# print(percentage_detected)
pass
return result, output
def stop():
"""_summary_
Returns:
_type_: _description_
"""
mcp4728.channel_a.value = 0 # start going forward
mcp4728.channel_b.value = 0 #go straight
return
def go():
mcp4728.channel_a.value = int(65535/1.6) #start going forward
mcp4728.channel_b.value = int(65535/2.7) #go straight
return
def speed_up():
#update the channel a value by a small amount
# Increase speed by updating channel A and B values
current_value = mcp4728.channel_a.value
if current_value < 65535:
new_value = min(65535, current_value + 1000) # Increase speed by 1000 units
mcp4728.channel_a.value = int(new_value)
print(f"Speed increased. New value: {new_value}")
else:
print("Maximum speed reached.")
def slow_down():
# Decrease speed by updating channel A and B values
current_value = mcp4728.channel_a.value
if current_value > 0:
new_value = max(0, current_value - 1000) # Decrease speed by 1000 units
mcp4728.channel_a.value = int(new_value)
print(f"Speed decreased. New value: {new_value}")
else:
print("Car stopped.")
#adapt this to the correct color scheme
# def detect_orange(frame, threshold=1000):
# '''
# Detect orange color within a given threshold.
# '''
# hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
# lower_orange = np.array([5, 100, 100], dtype="uint8") # Define lower orange range
# upper_orange = np.array([15, 255, 255], dtype="uint8") # Define upper orange range
# mask = cv2.inRange(hsv, lower_orange, upper_orange)
# # cv2.imshow("Orange_color", mask)
# return mask.sum() > threshold
def isRedFloorVisible(frame):
"""
Detects whether or not the floor is red
:param frame: Image
:return: [(True is the camera sees a red on the floor, false otherwise), video output]
"""
print("Checking for floor stop")
boundaries = getRedFloorBoundaries()
return isMostlyColor(frame, boundaries)
def detect_edges(frame):
# filter for blue lane lines
hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
#cv2.imshow("HSV",hsv)
lower_blue = np.array([90, 120, 0], dtype = "uint8")
upper_blue = np.array([150, 255, 255], dtype="uint8")
mask = cv2.inRange(hsv,lower_blue,upper_blue)
#cv2.imshow("mask",mask)
# detect edges
edges = cv2.Canny(mask, 50, 100)
#cv2.imshow("edges",edges)
return edges
def region_of_interest(edges):
height, width = edges.shape
mask = np.zeros_like(edges)
# only focus lower half of the screen
polygon = np.array([[
(0, height),
(0, height/2),
(width , height/2),
(width , height),
]], np.int32)
cv2.fillPoly(mask, polygon, 255)
cropped_edges = cv2.bitwise_and(edges, mask)
cv2.imshow("roi",cropped_edges)
return cropped_edges
def detect_line_segments(cropped_edges):
rho = 1
theta = np.pi / 180
min_threshold = 10
line_segments = cv2.HoughLinesP(cropped_edges, rho, theta, min_threshold,
np.array([]), minLineLength=5, maxLineGap=150)
return line_segments
def average_slope_intercept(frame, line_segments):
lane_lines = []
if line_segments is None:
print("no line segments detected")
return lane_lines
height, width,_ = frame.shape
left_fit = []
right_fit = []
boundary = 1/3
left_region_boundary = width * (1 - boundary)
right_region_boundary = width * boundary
for line_segment in line_segments:
for x1, y1, x2, y2 in line_segment:
if x1 == x2:
print("skipping vertical lines (slope = infinity")
continue
fit = np.polyfit((x1, x2), (y1, y2), 1)
slope = (y2 - y1) / (x2 - x1)
intercept = y1 - (slope * x1)
if slope < 0:
if x1 < left_region_boundary and x2 < left_region_boundary:
left_fit.append((slope, intercept))
else:
if x1 > right_region_boundary and x2 > right_region_boundary:
right_fit.append((slope, intercept))
left_fit_average = np.average(left_fit, axis=0)
if len(left_fit) > 0:
lane_lines.append(make_points(frame, left_fit_average))
right_fit_average = np.average(right_fit, axis=0)
if len(right_fit) > 0:
lane_lines.append(make_points(frame, right_fit_average))
return lane_lines
def make_points(frame, line):
height, width, _ = frame.shape
slope, intercept = line
y1 = height # bottom of the frame
y2 = int(y1 / 2) # make points from middle of the frame down
if slope == 0:
slope = 0.1
x1 = int((y1 - intercept) / slope)
x2 = int((y2 - intercept) / slope)
return [[x1, y1, x2, y2]]
def display_lines(frame, lines, line_color=(0, 255, 0), line_width=6):
line_image = np.zeros_like(frame)
if lines is not None:
for line in lines:
for x1, y1, x2, y2 in line:
cv2.line(line_image, (x1, y1), (x2, y2), line_color, line_width)
line_image = cv2.addWeighted(frame, 0.8, line_image, 1, 1)
return line_image
def display_heading_line(frame, steering_angle, line_color=(0, 0, 255), line_width=5 ):
heading_image = np.zeros_like(frame)
height, width, _ = frame.shape
steering_angle_radian = steering_angle / 180.0 * math.pi
x1 = int(width / 2)
y1 = height
x2 = int(x1 - height / 2 / math.tan(steering_angle_radian))
y2 = int(height / 2)
cv2.line(heading_image, (x1, y1), (x2, y2), line_color, line_width)
heading_image = cv2.addWeighted(frame, 0.8, heading_image, 1, 1)
return heading_image
def get_steering_angle(frame, lane_lines):
height,width,_ = frame.shape
if len(lane_lines) == 2:
_, _, left_x2, _ = lane_lines[0][0]
_, _, right_x2, _ = lane_lines[1][0]
mid = int(width / 2)
x_offset = (left_x2 + right_x2) / 2 - mid
y_offset = int(height / 2)
elif len(lane_lines) == 1:
x1, _, x2, _ = lane_lines[0][0]
x_offset = x2 - x1
y_offset = int(height / 2)
elif len(lane_lines) == 0:
x_offset = 0
y_offset = int(height / 2)
angle_to_mid_radian = math.atan(x_offset / y_offset)
angle_to_mid_deg = int(angle_to_mid_radian * 180.0 / math.pi)
steering_angle = angle_to_mid_deg + 90
return steering_angle
def plot_pd(p_vals, d_vals, error, show_img=False):
fig, ax1 = plt.subplots()
t_ax = np.arange(len(p_vals))
ax1.plot(t_ax, p_vals, '-', label="P values")
ax1.plot(t_ax, d_vals, '-', label="D values")
ax2 = ax1.twinx()
ax2.plot(t_ax, error, '--r', label="Error")
ax1.set_xlabel("Frames")
ax1.set_ylabel("PD Value")
ax2.set_ylim(-90, 90)
ax2.set_ylabel("Error Value")
plt.title("PD Values over time")
fig.legend()
fig.tight_layout()
plt.savefig("pd_plot.png")
if show_img:
plt.show()
plt.clf()
def plot_pwm(speed_pwms, turn_pwms, error, show_img=False):
fig, ax1 = plt.subplots()
t_ax = np.arange(len(speed_pwms))
ax1.plot(t_ax, speed_pwms, '-', label="Speed PWM")
ax1.plot(t_ax, turn_pwms, '-', label="Steering PWM")
ax2 = ax1.twinx()
ax2.plot(t_ax, error, '--r', label="Error")
ax1.set_xlabel("Frames")
ax1.set_ylabel("PWM Values")
ax2.set_ylabel("Error Value")
plt.title("PWM Values over time")
fig.legend()
plt.savefig("pwm_plot.png")
if show_img:
plt.show()
plt.clf()
video = cv2.VideoCapture(0)
video.set(cv2.CAP_PROP_FRAME_WIDTH,320)
video.set(cv2.CAP_PROP_FRAME_HEIGHT,240)
#wait for vid to load
time.sleep(1)
##fourcc = cv2.VideoWriter_fourcc(*'XVID')
##out = cv2.VideoWriter('Original15.avi',fourcc,10,(320,240))
##out2 = cv2.VideoWriter('Direction15.avi',fourcc,10,(320,240))
# speed = 8
# lastTime = 0
# lastError = 0
# kp = 0.4
# kd = kp * 0.65
# PD variables
#kp = 0.095
kp = 0.2
kd = kp * 0.1
lastTime = 0
lastError = 0
# counter for number of ticks
counter = 0
MAX_ITERATIONS = 2000 # Define the maximum number of loop iterations
# start the engines
go()
# arrays for making the final graphs
p_vals = []
d_vals = []
err_vals = []
speed_pwm = []
steer_pwm = []
stopSignCheck = 1
sightDebug = False
isStopSignBool = False
passedFirstStopSign = False
atStopLight = False
atStopLight = False
secondStopLightTick = 0
counter = 0
while counter < 3000:
print(counter)
print("SPEED", mcp4728.channel_a.value)
print("STEER", mcp4728.channel_b.value)
speed_value = mcp4728.channel_a.value
steer_value = mcp4728.channel_b.value
ret,original_frame = video.read()
# frame = cv2.flip(frame,-1)
frame = cv2.resize(original_frame, (160, 120))
# The resolution of the camera needed to be chosen so that
# the blue lines of the lane could be seen and the slope of each
# line could be determined by the OpenCV modules in our main Python code.
# Thus, we chose the maximum resolution supported by the camera that was also
# small enough to not hinder the performance of the program by making the processing
# very time and computation intensive; this resolution ended up being 160x120.
# cv2.imshow("original",frame)
if sightDebug:
cv2.imshow("Resized Frame", frame)
# reading the encoder data and changing the speed
time_diff = 7
with open("/sys/module/gpiod_driver/parameters/elapsed_ms", "r") as filetoread:
time_diff = int(filetoread.read())
print("Time diff", time_diff)
# Encoder time me when I check the encoder
if time_diff >= 120:
speed_up()
elif time_diff <= 110 and time_diff > 7:
slow_down()
# check for stop sign/traffic light every couple ticks
if ((counter + 1) % stopSignCheck) == 0:
# check for the first stop sign
if not passedFirstStopSign:
isStopSignBool, floorSight = isRedFloorVisible(frame)
if sightDebug:
cv2.imshow("floorSight", floorSight)
if isStopSignBool:
print("detected first stop sign, stopping")
stop()
time.sleep(2)
passedFirstStopSign = True
# this is used to not check for the second stop sign until many frames later
secondStopSignTick = counter + 200
# now check for stop sign less frequently
stopSignCheck = 3
# add a delay to calling go faster
go_faster_tick = counter + go_faster_tick_delay
print("first stop finished!")
mcp4728.channel_a.value = int(65535/1.6)
#speed_up()
#speed_up()
# check for the second stop sign
elif passedFirstStopSign and counter > secondStopSignTick:
isStop2SignBool, _ = isRedFloorVisible(frame)
if isStop2SignBool:
# last stop sign detected, exits while loop
print("detected second stop sign, stopping")
stop()
break
# makes car go faster, helps it have enough speed to get to the end of the course
# if isStopSignBool and counter == go_faster_tick:
# print("Going FASTER")
# speed_up()
# current_speed += .01
edges = detect_edges(frame)
roi = region_of_interest(edges)
line_segments = detect_line_segments(roi)
lane_lines = average_slope_intercept(frame,line_segments)
lane_lines_image = display_lines(frame,lane_lines)
steering_angle = get_steering_angle(frame, lane_lines)
#heading_image = display_heading_line(lane_lines_image,steering_angle)
#cv2.imshow("heading line",heading_image)
now = time.time()
dt = now - lastTime
if sightDebug:
cv2.imshow("Cropped sight", roi)
deviation = steering_angle - 90
# error = abs(deviation)
print("steering angle", steering_angle)
#constants for steering range
left_range = int(65535/4)
right_range = int(65535/1.2)
left = 8.8
right = 6.2
# PD code
error = -deviation
base_turn = 7.75
proportional = kp * error
derivative = kd * (error - lastError) / dt
# take values for graphs
p_vals.append(proportional)
d_vals.append(derivative)
err_vals.append(error)
# determine actual turn to do
turn_amt = base_turn + proportional + derivative
print("TURN AMNT", turn_amt)
# caps turns to make PWM values
# Map turn_amt to the steering range
# caps turns to make PWM values
if 7.2 < turn_amt < 7.8:
turn_amt = 7.75
mcp4728.channel_b.value = int(65535/2.7)
elif turn_amt > left:
turn_amt = left
print("TURN LEFT")
mcp4728.channel_b.value = int(65535/15)
elif turn_amt < right:
turn_amt = right
print("TURN RIGHT")
mcp4728.channel_b.value = int(65535/1.5)
else:
turn_amt = turn_amt
# take values for graphs
steer_pwm.append(turn_amt)
speed_pwm.append(current_speed)
# update PD values for next loop
lastError = error
lastTime = time.time()
# derivative = kd * (error - lastError) / dt
# proportional = kp * error
# PD = int(speed + derivative + proportional)
# spd = abs(PD)
# if spd > 25:
# spd = 25
# throttle.start(spd)
# lastError = error
# lastTime = time.time()
## out.write(frame)
## out2.write(heading_image)
key = cv2.waitKey(1)
if key == 27:
plot_pd(p_vals, d_vals, err_vals, True)
break
# update PD values for next loop
lastError = error
lastTime = time.time()
counter += 1
video.release()
##out.release()
##out2.release()
cv2.destroyAllWindows()
stop()
plot_pd(p_vals, d_vals, err_vals, True)
#plot_pwm(speed_pwm, steer_pwm, err_vals, True)
# GPIO.output(in1,GPIO.LOW)
# GPIO.output(in2,GPIO.LOW)
# GPIO.output(in3,GPIO.LOW)
# GPIO.output(in4,GPIO.LOW)
# throttle.stop()
# steering.stop()
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/kernel.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <asm/div64.h>
#define DEVICE_NAME "carencoder"
#define CLASS_NAME "carclass"
unsigned int irq_number;
struct gpio_desc *led_gpio;
struct gpio_desc *encoder_gpio;
static int elapsed_ms = 0;
ktime_t start_time, old_time, elapsed;
// Adds elapsed_ms to a parameters file under sys/modules/parameters
module_param(elapsed_ms, int, S_IRUGO);
static irq_handler_t encoder_irq_handler(unsigned int irq, void *dev_id, struct pt_regs *regs) {
// Calculates the elapsed time by getting the current time and subtracting the
// old time from it
ktime_t new_time = ktime_get();
elapsed = ktime_sub(new_time, old_time);
old_time = new_time;
elapsed_ms = ktime_divns(ktime_to_ns(elapsed),100000);
printk("Elapsed: %i\n", elapsed);
return (irq_handler_t) IRQ_HANDLED;
}
static int led_probe(struct platform_device *pdev) {
printk("Setting up encoder IRQ.\n");
old_time = ktime_get();
encoder_gpio = devm_gpiod_get(&pdev->dev, "userbutton", GPIOD_IN);
gpiod_set_debounce(encoder_gpio, 1000000);
irq_number = gpiod_to_irq(encoder_gpio);
//Checks if the irq request was successful
if (request_irq(irq_number, (irq_handler_t)encoder_irq_handler, IRQF_TRIGGER_FALLING, "button_irq", NULL) !=0) {
printk(KERN_INFO "Failed to request\n");
return -1;
}
printk("Successfully requested IRQ.\n");
return 0;
}
static int led_remove(struct platform_device *pdev) {
struct device *temp_dev;
// Frees the IRQ woah neat
temp_dev = &pdev->dev;
free_irq(irq_number, &temp_dev->id);
printk("IRQ Freed!\n");
return 0;
}
static struct of_device_id encoder_gpio_match[] = {
{
.compatible = "encoder-gpio",
},
{/* leave alone - keep this here (end node) */},
};
// Encoder GPIO driver
static struct platform_driver encoder_gpio_driver = {
.probe = led_probe,
.remove = led_remove,
.driver = {
.name = "this doesnt even matter",
.owner = THIS_MODULE,
.of_match_table = encoder_gpio_match,
},
};
// Module stuff and things
module_platform_driver(encoder_gpio_driver);
MODULE_DESCRIPTION("Use of the accursed gpiod library to do some blinking LED stuff");
MODULE_AUTHOR("Maaz Zuberi");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:encoder_gpio_driver");
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