Build a radar controlled by ESP32

ESP32 19-11-24

35 0

Tutorial plan

1- What is a radar ?

2- Operation of the radar controlled by ESP32:

3- Radar components

4- Radar mounting

5- Python Program

What is a radar ?

A radar (short for Radio Detection and Ranging) is a system that uses electromagnetic waves, specifically radio waves, to detect, locate, and track objects. It operates by transmitting radio waves and analyzing the signals that bounce back (echoes) after hitting an object. Here's a breakdown of its main components and functions:

Key Components

1- Transmitter: Generates radio waves and sends them into space.

2- Antenna:

Transmits the radio waves into a desired direction.

Receives the reflected waves (echoes) from objects.

3- Receiver: Processes the returned echoes to extract information.

4- Processor/Display Unit: Analyzes the data and displays it as images or signals for interpretation.

How Radar Works

1- Transmission: The radar emits a burst of radio waves.

2- Reflection: These waves travel through space, hit objects, and are reflected back toward the radar.

3- Reception: The radar antenna picks up the returning signals.

4- Processing: The time delay between transmission and reception, along with the strength of the reflected signal, helps calculate:

Distance to the object.

Speed of the object (using the Doppler effect).

Direction or bearing of the object.

Applications of Radar

Weather Monitoring: Detecting rain, storms, and other weather phenomena.

Air Traffic Control: Tracking and guiding aircraft.

Military: Detecting and tracking ships, planes, and missiles.

Maritime Navigation: Avoiding obstacles at sea.

Automotive: Advanced driver assistance systems like adaptive cruise control.

Space Exploration: Mapping surfaces of planets and moons.

Operation of the radar controlled by ESP32:

A radar system controlled by an ESP32 microcontroller, a servo motor, and an HC-SR04 ultrasonic sensor operates as a scanning or sweeping radar that maps its surroundings by detecting objects and measuring distances. Here's how it works:

1. Initialization:

The ESP32 initializes the servo motor and ultrasonic sensor.

It connects to the PC via USB or Wi-Fi, depending on the setup.

The PC runs visualization software (e.g., a Python script with libraries like Matplotlib or Processing for graphics).

2. Servo Scanning:

The ESP32 controls the servo motor to rotate the sensor incrementally over a specified range (e.g., 0° to 180°).

At each angle, the ESP32 pauses momentarily to allow the sensor to make an accurate distance measurement.

3. Distance Measurement:

- The HC-SR04 emits an ultrasonic pulse when triggered by the ESP32.

- It measures the time taken for the echo to return after bouncing off an object.

- The ESP32 calculates the object's distance.

4. Data Transmission:

The ESP32 sends the angle and measured distance to the PC in real time using serial communication (via USB or Wi-Fi).

5. Visualization:

- The PC software receives the data and plots it dynamically.

- A polar graph is typically used, where:

Angles represent the servo position.

Radii represent the measured distances.

- The screen updates continuously as the radar sweeps back and forth.

6. Continuous Scanning:

- Once the servo reaches its maximum angle (e.g., 180°), the ESP32 reverses the servo's direction for another sweep.

- The process repeats to create a continuous radar-like display.

Radar components

ESP32:

ESP32 card

Controls the radar system, collects data from the HC-SR04, and sends it to the PC for display.

Servo Motor:

Rotates the HC-SR04 sensor to enable scanning over a range of angles.

HC-SR04 Ultrasonic Sensor:

HC-SR04

Measures distance by emitting ultrasonic waves and calculating the time it takes for the echo to return after bouncing off an object.

PC:

Displays the radar's data as a visual map (e.g., polar plot) via a connected program (like Python or Processing).

Radar mounting

HC-SR04:

Connect the VCC and GND pins to the ESP32’s 3.3V and GND pins, respectively.

Connect the Trigger (TRIG) and Echo (ECHO) pins to GPIO22 et GPIO21 on the ESP32.

Servo Motor:

Connect the servo's power (usually red) to a 5V supply.

Connect the ground (black/brown) to the ESP32’s GND.

Connect the control (signal) wire (yellow/white) to GPIO23 pin on the ESP32.

Python Program

Here’s two programs with Python to control a radar system using an ESP32, a servo motor, an HC-SR04 ultrasonic sensor, and a PC for visualization.

Programming the ESP32 board with Micropython

Note: you must use these two libraries: hcsr04 and servo.

import machine
from hcsr04 import HCSR04
from machine import UART,Pin
from servo import Servo
import utime
# Initialize a UART objects
uart = UART(2, baudrate=115200)
sensor = HCSR04(trigger_pin=22,echo_pin=21,echo_timeout_us=1000000)
servo_pin = machine.Pin(23)
my_servo = Servo(servo_pin)
delay = 0.01
min = 15
max = 165
count = 1
while True:
    for i in range(min,max):
      my_servo.write_angle(i)
      distance = sensor.distance_cm()
      if distance > 1000 :
        distance=0
      print(i,',',distance)
      utime.sleep_ms(60)
    for i in range(max, min, -1):
      my_servo.write_angle(i)
      utime.sleep_ms(60)
      distance = sensor.distance_cm()
      if distance > 1000 :
        distance=0
      print(i,',',distance)

import machine

from hcsr04 import HCSR04

from machine import UART,Pin

from servo import Servo

import utime

# Initialize a UART objects

uart = UART(2, baudrate=115200)

sensor = HCSR04(trigger_pin=22,echo_pin=21,echo_timeout_us=1000000)

servo_pin = machine.Pin(23)

my_servo = Servo(servo_pin)

delay = 0.01

min = 15

max = 165

count = 1

while True:

for i in range(min,max):

my_servo.write_angle(i)

distance = sensor.distance_cm()

if distance > 1000 :

distance=0

print(i,',',distance)

utime.sleep_ms(60)

for i in range(max, min, -1):

my_servo.write_angle(i)

utime.sleep_ms(60)

distance = sensor.distance_cm()

if distance > 1000 :

distance=0

print(i,',',distance)

Python program executed by the computer

# Python + Arduino-based Radar Plotter
#
# ** Works with any motor that outputs angular rotation
# ** and with any distance sensor (HC-SR04, VL53L0x,LIDAR)
#
import numpy as np
import matplotlib
matplotlib.use('TkAgg')
import matplotlib.pyplot as plt
from matplotlib.widgets import Button
import serial,sys,glob
import serial.tools.list_ports as COMs
#
#
############################################
# Find Arudino ports, select one, then start communication with it
############################################
#
def port_search():
    if sys.platform.startswith('win'): # Windows
        ports = ['COM{0:1.0f}'.format(ii) for ii in range(1,256)]
    elif sys.platform.startswith('linux') or sys.platform.startswith('cygwin'):
        ports = glob.glob('/dev/tty[A-Za-z]*')
    elif sys.platform.startswith('darwin'): # MAC
        ports = glob.glob('/dev/tty.*')
    else:
        raise EnvironmentError('Machine Not pyserial Compatible')

    arduinos = []
    for port in ports: # loop through to determine if accessible
        if len(port.split('Bluetooth'))>1:
            continue
        try:
            ser = serial.Serial(port)
            ser.close()
            arduinos.append(port) # if we can open it, consider it an arduino
        except (OSError, serial.SerialException):
            pass
    return arduinos

arduino_ports = port_search()
#ser = serial.Serial(arduino_ports[0],baudrate=115200) # match baud on Arduino
port1="COM4"
ser = serial.Serial(port1,baudrate=115200)
ser.flush() # clear the port
#
############################################
# Start the interactive plotting tool and
# plot 180 degrees with dummy data to start
############################################
#
fig = plt.figure(facecolor='k')
win = fig.canvas.manager.window # figure window
screen_res = win.wm_maxsize() # used for window formatting later
dpi = 150.0 # figure resolution
fig.set_dpi(dpi) # set figure resolution

# polar plot attributes and initial conditions
ax = fig.add_subplot(111,polar=True,facecolor='#006d70')
ax.set_position([-0.05,-0.05,1.1,1.05])
r_max = 100.0 # can change this based on range of sensor
ax.set_ylim([0.0,r_max]) # range of distances to show
ax.set_xlim([0.0,np.pi]) # limited by the servo span (0-180 deg)
ax.tick_params(axis='both',colors='w')
ax.grid(color='w',alpha=0.5) # grid color
ax.set_rticks(np.linspace(0.0,r_max,5)) # show 5 different distances
ax.set_thetagrids(np.linspace(0.0,180.0,10)) # show 10 angles
angles = np.arange(0,181,1) # 0 - 180 degrees
theta = angles*(np.pi/180.0) # to radians
dists = np.ones((len(angles),)) # dummy distances until real data comes in
pols, = ax.plot([],linestyle='',marker='o',markerfacecolor = 'w',
                 markeredgecolor='#EFEFEF',markeredgewidth=1.0,
                 markersize=10.0,alpha=0.9) # dots for radar points
line1, = ax.plot([],color='w',
                  linewidth=4.0) # sweeping arm plot

# figure presentation adjustments
fig.set_size_inches(0.96*(screen_res[0]/dpi),0.96*(screen_res[1]/dpi))
plot_res = fig.get_window_extent().bounds # window extent for centering
win.wm_geometry('+{0:1.0f}+{1:1.0f}'.\
                format((screen_res[0]/2.0)-(plot_res[2]/2.0),
                       (screen_res[1]/2.0)-(plot_res[3]/2.0))) # centering plot
fig.canvas.toolbar.pack_forget() # remove toolbar for clean presentation
fig.canvas.set_window_title('Arduino Radar')

fig.canvas.draw() # draw before loop
axbackground = fig.canvas.copy_from_bbox(ax.bbox) # background to keep during loop

############################################
# button event to stop program
############################################

def stop_event(event):
    global stop_bool
    stop_bool = 1
prog_stop_ax = fig.add_axes([0.85,0.025,0.125,0.05])
pstop = Button(prog_stop_ax,'Stop Program',color='#FCFCFC',hovercolor='w')
pstop.on_clicked(stop_event)
# button to close window
def close_event(event):
    global stop_bool,close_bool
    if stop_bool:
        plt.close('all')
    stop_bool = 1
    close_bool = 1
close_ax = fig.add_axes([0.025,0.025,0.125,0.05])
close_but = Button(close_ax,'Close Plot',color='#FCFCFC',hovercolor='w')
close_but.on_clicked(close_event)

fig.show()

############################################
# inifinite loop, constantly updating the
# 180deg radar with incoming Arduino data
############################################
#
start_word,stop_bool,close_bool = True,False,False
while True:
    try:
        if stop_bool: # stops program
            fig.canvas.toolbar.pack_configure() # show toolbar
            if close_bool: # closes radar window
                plt.close('all')
            break
        ser_bytes = ser.readline() # read Arduino serial data
        decoded_bytes = ser_bytes.decode('utf-8') # decode data to utf-8
        #data =ser_bytes.decode('utf-8')
        print(decoded_bytes)
        data = (decoded_bytes.replace('\r','')).replace('\n','').replace(' ','')
        #print(data.split(','))
        if start_word:
            vals = [float(ii) for ii in data.split(',')]
            print(vals)
            if len(vals)<2:
                continue
            angle,dist = vals # separate into angle and distance
            if dist>r_max:
                dist = 0.0 # measuring more than r_max, it's likely inaccurate
            dists[int(angle)] = dist
            if angle % 5 ==0: # update every 5 degrees
                pols.set_data(theta,dists)
                fig.canvas.restore_region(axbackground)
                ax.draw_artist(pols)

                line1.set_data(np.repeat((angle*(np.pi/180.0)),2),
                   np.linspace(0.0,r_max,2))
                ax.draw_artist(line1)

                fig.canvas.blit(ax.bbox) # replot only data
                fig.canvas.flush_events() # flush for next plot
        else:
            if data=='Radar Start': # stard word on Arduno
                start_word = True # wait for Arduino to output start word
                print('Radar Starting...')
            else:
                continue

    except KeyboardInterrupt:
        plt.close('all')
        print('Keyboard Interrupt')
        break

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# Python + Arduino-based Radar Plotter

# ** Works with any motor that outputs angular rotation

# ** and with any distance sensor (HC-SR04, VL53L0x,LIDAR)

import numpy as np

import matplotlib

matplotlib.use('TkAgg')

import matplotlib.pyplot as plt

from matplotlib.widgets import Button

import serial,sys,glob

import serial.tools.list_ports as COMs

############################################

# Find Arudino ports, select one, then start communication with it

############################################

def port_search():

if sys.platform.startswith('win'): # Windows

ports = ['COM{0:1.0f}'.format(ii) for ii in range(1,256)]

elif sys.platform.startswith('linux') or sys.platform.startswith('cygwin'):

ports = glob.glob('/dev/tty[A-Za-z]*')

elif sys.platform.startswith('darwin'): # MAC

ports = glob.glob('/dev/tty.*')

else:

raise EnvironmentError('Machine Not pyserial Compatible')

arduinos = []

for port in ports: # loop through to determine if accessible

if len(port.split('Bluetooth'))>1:

continue

try:

ser = serial.Serial(port)

ser.close()

arduinos.append(port) # if we can open it, consider it an arduino

except (OSError, serial.SerialException):

pass

return arduinos

arduino_ports = port_search()

#ser = serial.Serial(arduino_ports[0],baudrate=115200) # match baud on Arduino

port1="COM4"

ser = serial.Serial(port1,baudrate=115200)

ser.flush() # clear the port

############################################

# Start the interactive plotting tool and

# plot 180 degrees with dummy data to start

############################################

fig = plt.figure(facecolor='k')

win = fig.canvas.manager.window # figure window

screen_res = win.wm_maxsize() # used for window formatting later

dpi = 150.0 # figure resolution

fig.set_dpi(dpi) # set figure resolution

# polar plot attributes and initial conditions

ax = fig.add_subplot(111,polar=True,facecolor='#006d70')

ax.set_position([-0.05,-0.05,1.1,1.05])

r_max = 100.0 # can change this based on range of sensor

ax.set_ylim([0.0,r_max]) # range of distances to show

ax.set_xlim([0.0,np.pi]) # limited by the servo span (0-180 deg)

ax.tick_params(axis='both',colors='w')

ax.grid(color='w',alpha=0.5) # grid color

ax.set_rticks(np.linspace(0.0,r_max,5)) # show 5 different distances

ax.set_thetagrids(np.linspace(0.0,180.0,10)) # show 10 angles

angles = np.arange(0,181,1) # 0 - 180 degrees

theta = angles*(np.pi/180.0) # to radians

dists = np.ones((len(angles),)) # dummy distances until real data comes in

pols, = ax.plot([],linestyle='',marker='o',markerfacecolor = 'w',

markeredgecolor='#EFEFEF',markeredgewidth=1.0,

markersize=10.0,alpha=0.9) # dots for radar points

line1, = ax.plot([],color='w',

linewidth=4.0) # sweeping arm plot

# figure presentation adjustments

fig.set_size_inches(0.96*(screen_res[0]/dpi),0.96*(screen_res[1]/dpi))

plot_res = fig.get_window_extent().bounds # window extent for centering

win.wm_geometry('+{0:1.0f}+{1:1.0f}'.\

format((screen_res[0]/2.0)-(plot_res[2]/2.0),

(screen_res[1]/2.0)-(plot_res[3]/2.0))) # centering plot

fig.canvas.toolbar.pack_forget() # remove toolbar for clean presentation

fig.canvas.set_window_title('Arduino Radar')

fig.canvas.draw() # draw before loop

axbackground = fig.canvas.copy_from_bbox(ax.bbox) # background to keep during loop

############################################

# button event to stop program

############################################

def stop_event(event):

global stop_bool

stop_bool = 1

prog_stop_ax = fig.add_axes([0.85,0.025,0.125,0.05])

pstop = Button(prog_stop_ax,'Stop Program',color='#FCFCFC',hovercolor='w')

pstop.on_clicked(stop_event)

# button to close window

def close_event(event):

global stop_bool,close_bool

if stop_bool:

plt.close('all')

stop_bool = 1

close_bool = 1

close_ax = fig.add_axes([0.025,0.025,0.125,0.05])

close_but = Button(close_ax,'Close Plot',color='#FCFCFC',hovercolor='w')

close_but.on_clicked(close_event)

fig.show()

############################################

# inifinite loop, constantly updating the

# 180deg radar with incoming Arduino data

############################################

start_word,stop_bool,close_bool = True,False,False

while True:

try:

if stop_bool: # stops program

fig.canvas.toolbar.pack_configure() # show toolbar

if close_bool: # closes radar window

plt.close('all')

break

ser_bytes = ser.readline() # read Arduino serial data

decoded_bytes = ser_bytes.decode('utf-8') # decode data to utf-8

#data =ser_bytes.decode('utf-8')

print(decoded_bytes)

data = (decoded_bytes.replace('\r','')).replace('\n','').replace(' ','')

#print(data.split(','))

if start_word:

vals = [float(ii) for ii in data.split(',')]

print(vals)

if len(vals)<2:

continue

angle,dist = vals # separate into angle and distance

if dist>r_max:

dist = 0.0 # measuring more than r_max, it's likely inaccurate

dists[int(angle)] = dist

if angle % 5 ==0: # update every 5 degrees

pols.set_data(theta,dists)

fig.canvas.restore_region(axbackground)

ax.draw_artist(pols)

line1.set_data(np.repeat((angle*(np.pi/180.0)),2),

np.linspace(0.0,r_max,2))

ax.draw_artist(line1)

fig.canvas.blit(ax.bbox) # replot only data

fig.canvas.flush_events() # flush for next plot

else:

if data=='Radar Start': # stard word on Arduno

start_word = True # wait for Arduino to output start word

print('Radar Starting...')

else:

continue

except KeyboardInterrupt:

plt.close('all')

print('Keyboard Interrupt')

break

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Build a radar controlled by ESP32

Tutorial plan

1- What is a radar ?

2- Operation of the radar controlled by ESP32:

3- Radar components

4- Radar mounting

5- Python Program

What is a radar ?

Key Components

How Radar Works

Applications of Radar

Operation of the radar controlled by ESP32:

Radar components

Radar mounting

Python Program

Programming the ESP32 board with Micropython

Python program executed by the computer

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Passion for robotics

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