In this lesson, we will show you how to connect 4 DOF robot arm to Raspberry Pi  and Use web browser to control the 4 servo joint of the arm.

No. Picture Device Qty. Accessories Link
1 Raspberry Pi board 1
2 MG995 or SG90 Servo Motor 4 M2.2*8 Self Tapping Screw x 2
M2*4 Self Tapping Screw x 1
Click here to buy
3 PCA9685 1

PCA9685 Raspberry Pi Physical Pin#
SCL SCL
SDA SDA
GND GND
VCC 5V
V+ Vin

PCA9685 Servo
PWM 15 Finger servo
PWM 14 Wrist servo
PWM 11 Arm servo
PWM 10 Base servo

Step 1: Please run following command to download  Linux script file:

wget http://osoyoo.com/driver/wifi-robot-arm/osoyoo-pi-arm.sh

then type the following command to install python program:

bash osoyoo-pi-arm.sh

Step 2: type following command to enter the folder osoyooarm

cd osoyooarm

Step 3:  Find your Raspberry Pi IP address by typing following command:

hostname -I

You will see the IP board IP address like this:

192.168.0.28 fd00:bc4d:fba4:fea2:8bea:ed3f:cfbd:ba1e

In above example, 192.168.0.28 is the IP address of our Pi. You need to use this IP address to update the python code in Step 4.

Step 4:  Type the following command to edit the file webcar.py

nano webarm.py

Change the default ip address 192.168.0.26 in line 15 to the raspberry pi IP address from Step 3, and cick “Ctrl”+”X” then “Y” to save the file and then click “enter” to exit

Step 5: Run the code by typing command

sudo python3 ~/osoyooarm/webarm.py

Step 6: In your PC or cell phone which is the same wifi network of your Raspberry Pi, open the browser and visit http://your_RaspberryPi_ip_address, you will see following UI

In the page, there are 4 Sliders which can control for servo joint, you can move the slider in order to rotate the servo and change arm and finger positions.

Reference:
Marcelo Rovai : Python WebServer With Flask and Raspberry Pi
https://towardsdatascience.com/python-webserver-with-flask-and-raspberry-pi-398423cc6f5d