Mobile Robot

A Mobile Robot That Moves In Response To Sounds

ABSTRACT

A mobile robot that moves in response to sounds means that by using a sound signal as applause sound to control a robot. This project is the combination of machine, electronic, programming and sensor. Robot has the ability to interact with physical objects and to be given electronic programming to function a specific task or a whole range of actions.

We believe that by using simple sound signal to become our communication medium to robot is the first choice so we using applause sound. This robot will move in response with the number of applause sounds that given by the user according to our programming to the PIC.

1) SYSTEM SPECIFICATION

Background Information

First of all, what is a robot? Robot is an electro-mechanical machine which consists of mechanical parts and electrical circuits. In this electro-mechanical machine, it is guided by computer or electronic programming and thus is able to do task on its own after receiving the instruction from the user.

The mainly design about robot can be described by the following properties:

* It is an artificial intelligence agent.

* Have a certain ability and intelligence level, to the automatic control or environment or pre-programmed sequence-based choice

* It can function with one or more servo motor at the robot arm.

* It is programmable and followed the instruction to complete task.

* It can be a flexible movement

* It can manipulate things in its environment.

* It can be mounted a robot arm on the mobile robot to become a function of transportation.

What is a mobile? Mobile can be define as capability of moving or of being moved readily from place to place. It refers to an automatic machine that is capable of moving in a given environment on itself after being program by the user. In general, the mobile robot needs input and output to perform movement. Figure 1.1 shows the data processing from input to output of the robot. Basically the input is from the sensor and programming of the ICs.

System Aim:

The aim is to build a mobile robot moves in response to the sound signal given by the user (applause).

* To design circuits work by using different varieties of sensors.

* To used communication medium to control the robot function.

* To prevent the robot move out of the certain area by using the line follower, the robot that can detect and follow line which is drawn on the floor.

* The robot used four dc motor and four servo motor to action.

* Learn how to troubleshoot errors occurred electrically and mechanically.

Characteristics:

(i) The Robot design in an average size and can use in the factory.

(ii) Robot should respond to the sound to approx within in 1 sec

(iii) When other signal is received at the microphone, the robot will ignore them as the mobile robot is programmed to receive applause signal only. This is because of the low-pass filter used in the project.

(iv) The black line will guide the mobile robot to move to the end of the line, so that the mobile robot won't reach out of the black line.

2) PROPOSED SOLUTION

2.1) Specification of the solution

Top level diagram:

Descriptions of individual modules:

Electret Microphone:

Microphone is a sensor which detects sound signals and produces an electrical image of the sound. Microphone detect the sound by taking the varying pressure waves in the air and then converts them into varying electrical signals. The electret microphone is very sensitive, very durable and extremely compact in size and has low power requirements. It has been used in many applications whereas it is small and inexpensive microphones with good performance characteristics.

Filters:

Filters are electronic circuits which allow electronic signals of certain frequencies to pass through the filter, while blocking or attenuating electronic signals of other frequencies. A low-pass filter is a filter that passes low frequency signals but attenuates signals with frequencies higher than the cutoff frequency. The electrect microphone will only allows the sound created from applause sound to pass through the filters.

Operational Amplifier:

The amplifier is amplifies the signal received by the electret microphone and passed through the Low-pass filter. It is a very important device in this system because the output signal of the microphone is very weak and the PIC microcontroller might not be able to detect the signal if it is not amplified.

IR Sensor:

The figure above shows a pair of IR sensors (transmitter and receiver). When the transmitter (infrared) emitting light into the white field, the light will be reflected almost entirely by the white areas. Conversely, when the transmitter emits light into dark areas or black, the light will be absorbed by the dark areas, so that the light reaching the receiver is low. By applying the sensors at the front and rear bottom of the robot, it sends the signal to the PIC whether it has detected either white or black line on the floor, then the PIC will control the movement of the motor so that it won't reach out of the black line. Therefore, we can make sure that the robot can move to the desired destination.

Control Unit:

The control unit uses 4 input ports and 7 output ports. The input pins are used by the sound input signal and the IR sensors while the output pins are used to control the DC motors (line follower) and servo motors. The programming done by user will be downloaded to the PIC and it will accept the input signal and produce a proper output to control the motors. Inside the control unit has their own ADC function which can receive the signal from operational amplifier and convert it into 1 bits binary code. The amplified analog signal from operational amplifier will be converted by ADC to a digital output. Another receive signal from IR sensors and convert it into 3 bits binary code. This is needed because PIC can only analyze digital input properly.

Line Follower:

In the line follower, Infrared sensors are used to sense the path which is drawn on the floor. Robot should read for identifying his position in some time, after that the control unit will create for robot some orders to respect components in purposes of making correct movements of the robot. The DC motor will move robot forward and backward on the line follower. Gears are used between the motors and wheels to control the movement of the robot. All the DC motors are controlled by the control unit.

Servo Motor:

A servomotor is an electromechanical device in which an electrical input determines the position of the armature of a motor. Most servo motors can rotate about 900 to 1800. Some rotate through a full 3600 or more. The servo motor precision positioning makes them ideal for robot arms, legs, rack and pinion steering. The servo motor will move the robot arms upwards and rotate the body of the robot so that the mobile robot will change its direction. The robot arm is used to catch item and transfer it to another container. The robot arm is a combination of servo motor, three of them are used to joints of the robot arm which from 00 to 900 and the fourth one is used as a base to rotate the body of robot arm from 00 to 1800.

Power Supply:

The power supply is use to turn on the mobile robot. The supply is taken directly from automobile battery. The voltage supplied into the logic circuit is stepped down using a 9V regulator.

The base of the robot arm will rotate 180 degree and the robot arm will put down the item on the other side of platform

2.2) Method for testing and system verification

1) Testing individual block

a) Electret Microphone: The sensitivity of the electrets microphone must be high enough to response to the applause sound

b) Filters: Use a low-pass filter. Other type of sounds with high frequencies will be filtered by the filters.

c) Op-Amp: Use a higher gain amplifier. This is because high amplifier can used to amplify the signal received by the microphone so that it can detect weaker applause sound from a further range

d) Control Unit: Test sound detection part and IR sensor part individually. Apply different level of voltage to it and monitor its output in the form of 1 bit binary code.

e) Line Follower: Using three IR sensors, then the robot will stay middle in the line.

f) Servo Motor: Adjust the turn on time of the motor properly to get a desired angle of movement.

2) The complete system is installed on an automobile and all possible input is tested for required output.

3) Dynamic testing of the mobile robot on a large and flat surface with no noises around. Once the mobile robot detects the first sound, it started to move forward on line follower until the robot stop moving when the end of the line is detected. Then, when it detects the second sound, the robot arm will start to move down and catch item. When the robot detects the third sounds the robot arm will rise up and reverse back to original position. When the fourth sound is received the base of the robot arm will rotate 1800 and the robot arm will put down the item on the other side of platform.

4) Supply automobiles with the system fitted to selected commercial users for their evaluation and comments.

3) RESOURCE REQUIRED

3.1) Major components with prices and sources

No.

Description

Quantity

Price(Unit)

Price(Total)

Supplier

1

PIC16F877

1

24.00

24.00

Farnell

2

Resistors

30

0.05

1.50

Farnell

3

Variable resistors

1

1.00

1.00

Farnell

4

Capacitors

20

0.20

4.00

Farnell

5

Diodes

4

0.20

0.80

Farnell

6

5V Relay

4

2.00

8.00

Farnell

7

LM741

2

5.00

10.00

Farnell

8

LM7805

1

2.00

2.00

Farnell

9

LM7809

1

2.00

2.00

Farnell

10

Electret Microphone

1

3.00

3.00

Farnell

11

LEDs

10

0.50

5.00

Farnell

12

Transistor

4

0.50

2.00

Farnell

13

Servo Motor

4

70

280

Cytron

14

9V DC Motor

2

5.00

10.00

Cytron

15

Rubber Tires

4

2

8

nixie

16

Robot Arm

1

100.00

100.00

Cytron

17

9V Battery

3

8.90

26.70

Farnell

18

SPST switch

1

1.00

1.00

Farnell

19

SPDT switch

1

1.00

1.00

Farnell

20

Gears

20

0.20

4.00

nixie

21

Crystal Oscillator

2

4.00

8.00

Farnell

22

Infrared SENSOR

16

1.00

16.00

nixie

21

Miscellaneous

--

--

20.00

Total cost

RM

538.00

3.2) Design and implementation tools

1) Microcontroller code development tools:-

a) PIC Compiler

b) PIC Programmer

c) PIC Development Board

2) PCB design tools and manufacturing facilities

a) Eagle

b) Multisim

3) Testing tools

Multimeter

4) GANTT CHART

Task

W1

W2

W3

W4

W5

W6

W7

W8

W9

W10

W11

W12

Preliminary Design

Detailed Hardware Design

Detailed Software Design

Complete Sensors Part

Complete Actuators Part

Complete Control Unit Part

Build System

Test System

User Trials

Preliminary Design: Brainstorm the design and rough out the top level design.

Detailed hardware design: Obtain the components and complete the detailed design of the hardware.

Detailed software design: Complete the detailed design of the software.

Complete Sensors Part: Complete building and testing of all required sensors.

Complete Actuators Part: Complete building and testing of actuators part including actuator interface.

Complete Control Unit Part: Complete coding and testing of the microcontroller.

Build System: Combine all sub-parts into a complete system.

Test System: Test the completed system.

User Trials: Supply automobiles with the system fitted to selected commercial users for their evaluation and comments.

5) CONCLUSION:

This group project design is proposed to design a mobile robot that responses to sound. The mobile robot reacts accordingly to the sound output from the applause. Initially, the mobile robot remains idle when the power is on. When the mobile robot receives the first sound, the microphone will detect the signal and it will pass through the filter and then be amplified by the operational amplifier. The amplified signal will be sent to the control unit to be processed.

The communication medium that used to control the robot function is applause sound. The robot will ignore other sound signal excepted the applause signal that we programmed in the mobile robot. While an applause sound is received, the robot will start to perform task. As a conclusion, this mobile robot is an interesting robot and can be use in any industrial side.

6) REFERENCES

· http://www.alldatasheet.com/datasheet-pdf/pdf/75016/MICROCHIP/PIC16F877.html

· http://kids.britannica.com/comptons/art-53254/In-a-DC-motor-electrons-from-the-DC-power-supply

· http://www.kmitl.ac.th/~kswichit/ROBOT/Follower.pdf

· http://www.robotgames.net/robotgames/Event_Rules/2002_line_follower.htm

· http://www.dw-world.de/staticfiles/pdf/dwfz/Operational_Amplifiers.pdf

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