I.Objective
II.Parts and Devices
III.Hardware Installation
IV.Circuit Connection
V.Software Installation

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In this lesson, our Raspberry Pi robot car will use Ultrasonic sensor to detect obstacles and make automatic driving and avoid collision.



No. Picture Device Qty. Accessories Link
1 Ultrosonic Sensor 1 M1.4*8 Screw x 4
M1.4 Nut x 4		 Click here to buy
2 Servo Motor 1 M2.2*8 Self Tapping Screw x 2
M2*4 Self Tapping Screw x 1		 Click here to buy
3 Mount Holder for Ultrasonic Sensor 1 M1.4*8 Screw x 4
M1.4 Nut x 4
M2*4 Self Tapping Screw x 1		 Click here to buy
4 20Pin jumper wire female to female 20cm some
5 Philips screwdriver 1 Click here to buy


Step 1: You must complete Lesson 1 basic frame work

Step 2: Install servo motor at the front of upper car chassis with 2pcs M2.2*8 Self Tapping Screws

Step 3: Install Ultrasonic Module to mount holder with 4pcs M1.4*8 screw and M1.4 nuts

Step 4: Install mount holder for Ultrasonic Module on servo motor with M2*4 Self Tapping screw



Connect SG90 servo motor to PWM 15 of PCA9685 compatible module, and connect GND and VCC of ultrasonic module to GND and V+ of PCA9685 compatible module, then connect TRIG and ECHO of ultrasonic module to GPIO20 and GPIO21 of raspberry pi as following graph (Remember : DO NOT remove any existing wires installed in Lesson 1 ):



Make sure you have installed rpi.gpio and adafruit-pca9685 library in lesson 1 .

Download the python code by typing following command in your Raspberry Pi terminal:

wget http://osoyoo.com/driver/picar/picar-obstacle-avoid.py

Turn on the battery of your car and  your servo and run the program,

If you are using Python 2 in Raspberry Pi 3, type:

python picar-obstacle-avoid.py

or if you are using Python 3 in Pi 4, type :

python3 picar-obstacle-avoid.py

Your servo will rotate the ultrasonic sensor to front position for 3 seconds. If your sensor is not facing front direction, please turn off the battery or press Ctrl-C key to stop the program. Then remove the sensor from servo and re-install it, make sure it faces front and fix the position with screw, now your can type same command  python picar-obstacle-avoid.py  and run the program again.

Now the car will automatically make obstacle avoidance auto driving.