IoT based �Mobile Dexterous Manipulator

B-Tech Final Year Project�Department of Instrument Technology�Andhra University College of Engineering 

Introduction

• Aim : To develop a working model of a mobile dexterous robotic system. 
• Salient Features :  
• Vertical Mobility 
• Dexterity of Robot Arm
• IoT network for wireless control
• Smartphone App as the Control House
• Web live streaming
• Specialty : Amalgamation of Robotics and IoT is the key element of this functioning model. 
• All components selected and designed meticulously to meet the requirements and compatibility of the robotic system.

• Electronics of Mobile Dexterous Manipulator :
• Microcontroller – ESP32 WROOM 
• Motors - 
• SG90
• MG996R
• RKI-1147
• Power Unit (SMPS)
• DPDT Switch
• ESP32 CAM
• Mechanics of Mobile Dexterous Manipulator :
• 3D printing of Robot Arm
• Design of Mobile Base Module with tin and iron
• Structure and assembly of the whole system

Key Elements

Development

• The Mobile Dexterous Manipulator is designed to achieve the functional goals and consists of two main modules : 

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• Robotic Arm Module
• Mobile Base Module

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• The Robotic arm module is essentially a manipulator with an end-effector capable of performing tasks like pick-n-place and the end-effector can be changed based on the application.
• The mobile base module is responsible for the vertical mobility of the robotic system.

IoT :

• Human to Machine Interaction has been made easier.
• Cloud IoT has given the capability to monitor and control systems remotely over a wide geographical region. 
• Aggregation of Data and easy access to computational systems is the key factor for the use of cloud network in this project.
• Blynk IoT cloud and app dashboard is used to develop control interface.
• Cloud API (Application Programming Interfaces) is a software interface that allows one computer program to make its data available for other programs to use. 

Circuit�Diagram of�Robot Arm

Circuit�Diagram of�Mobile Base

Robotic Arm Module

• The Robotic Arm is fabricated by using 3D printing process.
• ABS (acrylonitrile butadiene styrene) is used for the fabrication process.
• This Robotic arm has five degrees of freedom and it is determined by using Grubler's Criterion.
• The functionality of this Manipulator includes three important components, They are :
• ESP 32 WROOM 
• Blynk IoT Cloud 
• Application Development.

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ESP32 WROOM DevKit

• ESP32 WROOM is a Low cost, Low powered system on chip microcontroller with integrated Wi-Fi and dual-mode Bluetooth.
• Features of ESP32 WROOM :
• Xtensa® single-/dual-core 32-bit LX6 microprocessor(s)
• 448KB ROM
• 520KB SRAM
• Wi-Fi: 802.11 b/g/n
• Bluetooth: v4.2 BR/EDR and BLE (shares the radio with Wi-Fi)

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• This Microcontroller has a total of 39 multipurpose pins
• In those 39 pins 32 pins are GPIO pins
• 5V/3.3V power I/O pins
• I2C SCL and SDA
• 2 x 8-bit DAC
• 16 x 12-bit ADC
• 3 x GND pins, etc.
• As shown in the figure each pin will have multiple functionality.
• We have used SDA and SCL pins i.e. pin 21 and pin 22 to communicate with the PWM servo driver (PCA9685) in order to control the servo motors by varying the PWM signals.
• In this way by using this PWM servo driver we could be able to control 6 servo motors i.e. 3 x SG90 and 3 x MG996R.

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Blynk IoT Cloud

• Blynk IoT Cloud is a cloud-based platform that allows users to easily build and deploy IoT applications and projects. It provides a user-friendly interface for designing and programming custom dashboards, mobile apps, and web interfaces to control and monitor IoT devices and sensors in real-time.
• With Blynk IoT Cloud, you can quickly connect your hardware devices to the cloud and access them from anywhere in the world via the internet. The platform supports a wide range of popular IoT development boards, such as Arduino, Raspberry Pi, ESP32, and more.
• We have created 6 data streams of integer type and gave the pin names as V0,V1,...etc.
• These data streams will enable us to communicate with the ESP 32 by changing the input values in the web dashboard or app dashboard
• To make this communication possible first we need to install Blynk library in ArduinoIDE.

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• First picture is the app dashboard and second picture is the web dashboard.
• As shown in the figure we can use both laptop and mobile phone to control the servo motors.
• Here we have assigned each slider with respective data stream.
• Each slider will have their own range.
• Grip (V0) ranges from 0 to 90 degrees.
• Wrist-pitch (V1) ranges from 0 to 140 degrees.
• Wrist-roll (V2) ranges from 0 to 180 degrees.
• Elbow (V3) ranges from 0 to 130 degrees
• Shoulder (V4) ranges from 0 to 125 degrees 
• Waist (V5) will send three different values ( 81(CW), 90(STOP), 108(CCW)) as it is a continuous control servo motor. 

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Cloud API :

• API – Application Programming Interface
• API is a software intermediary that allows two applications communicate with each other. 
• APIs are essentially access pathways that enable extraction and sharing of data across organizations.

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• In this project, we have created cloud API for the communication of Blynk control with the robotic system over an URL based interface.

API Control :

• HTTPs REST API has been created to access blynk cloud through any computer with internet access. 
• https://blr1.blynk.cloud/external/api/get?token=XQUByLaUC2myhBOXSqzFTuaw3q1_7NSx&v3
• Here, "token=xxxx" is the authorization code for the blynk cloud
• &vx is the pin name (v0,v1,v2,v3)
• vx=value gives a value to the selected pin 

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App Development MIT App Inventor

• MIT App Inventor is an online platform with features to enable fluid designs for smartphone app development .
• It has 2 main editors : 
• Design editor
• Blocks editor
• The design editor is a space where the user interface can be designed with various tools available.
• Blocks editor is the brain of the inventor which follows a drag and drop approach to develop meaningful algorithmic logics for the working of the buttons in the Design.
• We have used this platform to design a functioning android app which controls the Arm over WiFi.

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• The illustrated is the code blocks for the Increase Button (+) of the app.
• The logic in MIT App Inventor is a universal algorithmic language.
• This code block here has a logic for increment of 5 degrees angle of the motor (vX) when pressed once.
• The if_then ladder ensures that the initial Zero position of the grip angle is at 90^o .
• When the ladder is satisfied, the input is given to the Blynk Cloud API which relays the  control data.

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Drag-n-drop ladder logic

Web Streaming 

• To enable this feature in our project we have installed ESP32 CAM unit onto the robot arm.
• This enables live video feed of the robot arm point-of-view.
• Remote monitoring of the robot environment is possible. 
• Camera view can be changed with the robot arm manipulator. 

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• ESP32 CAM is a competitive small size camera module that can operate independently as a micro system.

Live feed interface :

• The data from ESP32 CAM relays to the Blynk cloud which is then linked to the App developed for the control of the arm.
• The app is designed in such a way that the control blocks and the live feed feature are simultaneously accessible to the operator. 
• Start/Stop buttons are also added to allow the option to turn the camera ON/OFF. 
• Since the ESP32 CAM module is an independent controller, its code is directly linked with the cloud network.
• The cloud IoT system combines the camera with the ESP32 WROOM microcontroller, which enables control over the same Wi-Fi connection.

Selection and placement of motors

• Servo Motor : it is a motor consisting the servo closed loop system where the feedback signal drives the motor.
• In this project, the following motors are selected for different purposes : 
• SG90 – For Gripper, wrist pitch, and wrist roll (3)

              Wt. 9g, Torque 1.8kgcm, Op. Voltage 5V

• MG996R – For elbow, shoulder, and waist (3)

              Wt. 55g, Torque 9.4kgcm, Op. Voltage ~7V

• RKI-1147 – For base wheels

              Wt. 200g, Torque 5kgcm, Op. Voltage 12V

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SG90 Servo Motor

MG996R Servo Motor

RKI-1147 Johnson High Torque DC Motor

Placement of motors on the arm: 

RKI-1147 high torque motor installed with the wheels of the mobile base module.

SG90 Installed and calibrated on the robot arm .

DPDT Switch : 

• DPDT – Double-Pole Double-Throw Switch is electromechanical switch consisting of 2 inputs and 4 outputs. 
• Each input has 2 equivalent outputs.
• The switch has 3 states ON, OFF, ON where the main difference between the two ON states is the polarity which is quite opposite to each other.
• POLE refers to the number of circuits controlled by the switch.
• THROW refers to the extreme position of the actuator.
• In DPDT ON-OFF-ON switch, two separate SPDT switches are operated by the same actuator.

Mobile Base Module

• The Mobile Base is designed uniquely to exhibit vertical mobility over a cylindrical surface such as poles or trees.
• Specialty : Extends work envelope of the robot arm.

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• Components :
• Platform for robot arm
• Wheels (6)
• Mechanical structure

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• A 3D model was designed with a circular ring and hexagonal ring as 2 faces of the body.
• The circular ring is made of Iron.
• The hexagonal face and the supporting rods are made of Tin.
• Structure was built together with Tin smithy and welding.

Structure of Base

• Circular ring (top face)
• Inner Diameter – 30cm
• Thickness - 3cm
• Hexagonal Ring (bottom face)
• Side Length – 15cm
• Inner Diameter – 30cm
• Side Width – 1.5cm
• Side height - 3cm
• Connecting Bars (x4)
• Length – 1.5cm
• Width – 1.5cm
• Height – 12cm
• 6 wheels are installed out of which 3 are powered with RKI1147 motors. 
• The other 3 wheels are supporting wheels for the vertical movement.

Powering of the system

• To ensure the power supply to the whole robotic system, we have chosen to install 2 different power units for the robot arm module and base module respectively.
• Selection - SMPS (Switching Mode Power Supplies) are highly efficient compact power supply units. 
• The 2 power units are : 
1. SMPS 1 – ATX  - used to power 
• ESP32
• ESP32 CAM
• PCA 9685 (Servo Driver)
• SG90 Servo (x3)
• MG99x (x3) 
2. SMPS 2 – 12V Power Supply is installed to power the Base Module supported by 3 RKI1147 high-torque DC Motors. 

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Power supply of Mobile Dexterous Manipulator :

Thank You!

Project done by :

K. Eswara Chandra   319106816024

G. Naman Sreyas      319506810007

N. Kamalesh              319106816038

T. Prasad                     319106816053