PROJECT OUTLINE The main objective is to control the motion of a robot using wrist movements. If we move our arm towards right, then the robot would move towards right, if we move our wrist towards left, then the robot would move left, the same case in moving front or backwards. This is done by using an accelerometer. The device consists of a surface micro machined capacitive sensing cell (g-cell) and a signal conditioning ASIC contained in a single package. The sensing element is sealed hermetically at the wafer level using a bulk micro machined cap wafer. An accelerometer has fixed and movable capacitances in it. When shifted from its initial position, the movable capacitances are displaced which lead to a change in the value of the capacitance. The value of the robot velocity changes in accordance with this changed capacitance as we move the accelerometer attached to a glove on our hand. An Ultrasonic sensor is used for proximity detection. If there is any obstacle within 30cm of the robot’s path, pat h, then the motors would stop, halting all movement. A vibrator attached to the user’s glove would vibrate in this case, thereby telling the user to move backwards. DC motors are used to move the wheels whee ls of the robot. robo t. A DC motor is a mechanically commutated electric motor powered from direct current (DC). The stator is stationary in space by definition and therefore so is its current. The current in the rotor is switched by the commutator the commutator to also be stationary in space. This is how the relative angle between the stator and rotor magnetic flux is maintained near 90 degrees, which generates the maximum torque. A wired camera is placed on top of the robot which sends live footage back to the laptop. Arduino is used to run the t he whole who le project. proj ect. Arduino A rduino is a a single-board single-board microcontroller designed to make the process of using electronics in multidisciplinary in multidisciplinary projects more accessible. The hardware consists of a simple open source hardware board designed around an 8bit Atmel bit Atmel AVR AVR microcontroller, though a new model has been designed around a 32-bit Atmel ARM. Atmel ARM. The software consists of a standard programming language compiler and a boot a boot loader that executes on the microcontroller. the microcontroller.
It is also note worthy that we use an external chip (motor driver) to drive the DC motors because an arduino board can only supply voltage up to 5V while the dc motors used in the robot work at 12 V.
1|Page
COMPONENTS REQUIRED
1 Arduino board 1 Ultrasonic Sensor 1 serial USB cable 1 mobile vibrator 1 accelerometer Chassis 1 adapter 2 DC motors Connecting wires 1 caster wheel
DESCRIPTION OF COMPONENTS USED ARDUINO BOARD Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. The microcontroller on the board is programmed using the Arduino programming language (based on Wiring on Wiring)) and the Arduino development environment (based on Processing) on Processing).. It has an ATmega AT168 microcontroller that has a pre-installed bootloader, so one can download code to the board using only a USB-serial connection. Arduino projects can be stand-alone or they can communicate with software running on a computer .
2|Page
Figure 2(Arduino Board)
Figure 3(Arduino Board)
3|Page
1. 2. 3. 4. 5. 6. 7.
USB Jack Power Jack Voltage Regulator Digital Input Pins Analog Input Pins Power Pins Reset Button
USB CABLE The Arduino Duemilanove connects to a host PC with a simple USB cable. The Duemilanove comes with an FTDI USB-serial converter chip, so the device mounts as a "virtual COM" port from the perspective of the host PC.
Figure 4 (USB cable)
MOTORDRIVER BOARD(L293D) The bot runs on two dc motors these DC motors work on a 12 Volt DC supply. The problem here is evident. The Arduino Board has an output signal of 5V. So to run the motors a Motor Driver Board is used. This board uses the IC L293D.The board is powered by a 12V Adapter which is plugged into an electrical output. Using this board the input to the motors is controlled through inputs from the arduino which itself is being powered by the Motor Driver,by Monitoring the potential difference between the two terminals if the motor the board also enable us to vary the speed of the motors and hence the bot. Therefore the motor Driver is used to operate the motors using an arduino without connecting the two, and simultaneously allows us to control their speeds.
4|Page
ULTRASONIC DISTANCE SENSOR
Figure 5 (Working of Ultrasonic Sensor)
Figure 7 (Ultrasonic Sensor)
Figure 8 (Connections of Ultrasonic Sensor to A rduino)
5|Page
An Ultrasonic sensor has two transducers: an ultrasonic speaker and a matching microphone. When triggered by a digital signal, the speaker emits a modulated burst (or "ping") of ultrasonic sound. This sound then travels through the air; if it hits a nearby object, it is reflected back to the microphone. The microphone has a circuit to amplify and detect the reflected ping, and the device signals a digital "true" if it receives the reflected sound. By measuring the interval between the transmitted pulse and the received signal, the Arduino can determine distance to the object, by using a simple formula based on the speed of sound (approximately, one foot or 30 cm per millisecond).
MOBILE VIBRATORS
Figure 10 (Mobile Vibrator)
6|Page
Figure 11 (Connections of a buzzer/vibrator with Arduino)
A mobile vibrator is a device used to generate vibrations, generally of high frequency such that the user is able to perceive them. Its connections to the arduino are identical to that of the buzzer, that is, a vibrator is also attached to a digital pin of the arduino.
ACCELEROMETER We are using the pololu 0J2300 which is a capacitive type low current accelerometer. A capacitive accelerometer uses a sensing mechanism, known as a capacitive acceleration sensor, to measure both static acceleration and dynamic acceleration forces. With consideration to all accelerometers, there typically is some sort of electrical circuitry wired to the sensing mechanism in order to portray the output, or voltage, of its measurements.
Static acceleration force is generated by a gravitational pull. When measuring static acceleration with a capacitive accelerometer, the measurements would portray the angle of tilt at which the device is being held or suspended in relation to the Earth's gravitational pull. A common capability of many modern cell phones, smart phones and personal digital 7|Page
assistants (PDAs) is that the orientation of the screen changes in relation to the angle at which the device is being held.
Dynamic acceleration force is generated by vibrations from movement. Measuring vibrations allows a capacitive accelerometer to determine in which direction the device is moving and at what speed. Additionally, dynamic acceleration can be measured to track the impact that an object encounters.
8|Page
9|Page
ARDUINO CODE
#include
const int ping = 12; int vib=13; //int buzz=2;
int lp=4; int ln=5; int rp=8; int rn=9; int speedl=255; int speedr=255; int sensex=A0; int sensey=A1; int debug =1; int handle; int c=0; double theetax,theetay; const double precision = 255; double meanx,meany; void setup(){ 10 | P a g e
Serial.begin(9600); handle=Serial.read(); pinMode(lp,OUTPUT); pinMode(ln,OUTPUT); pinMode(rp,OUTPUT); pinMode(rn,OUTPUT);
pinMode(vib,OUTPUT); // pinMode(buzz,OUTPUT); Serial.begin(9600);
calib(); } void loop(){
if(handle !=1) { int valx = analogRead(sensex); int valy = analogRead(sensey); speedl = theetax*(meanx - valx); speedr = theetay*(meany - valy); Serial.print(meanx); Serial.print("
");
Serial.print(meany); Serial.print("
11 | P a g e
");
Serial.print(valx); Serial.print("
");
Serial.println(valy); if(valxmeany+50){ speedl=speedl*(-10); verify(); left(); } else if(valy
else { verify(); forward();
} } if(valx>meanx+20){ if(valy>meany+50){ speedl=speedl*(-10);
12 | P a g e
verify(); left(); // right(); } else if(valy
else { verify(); back();
} }
//delay(100); } else{ c=Serial.read(); if(c =='f')
13 | P a g e
forward(); if(c == 'b') back(); if(c == 'l') left(); if(c == 'r') right(); }
long duration, cm;
// The PING))) is triggered by a HIGH pulse of 2 or more microseconds. // Give a short LOW pulse beforehand to ensure a clean HIGH pulse: pinMode(ping, OUTPUT); digitalWrite(ping, LOW); delayMicroseconds(2); digitalWrite(ping, HIGH); delayMicroseconds(5); digitalWrite(ping, LOW); pinMode(ping, INPUT); duration = pulseIn(ping, HIGH);
// convert the time into a distance cm = microsecondsToCentimeters(duration); 14 | P a g e
if(cm<30) { digitalWrite(vib,HIGH); //
digitalWrite(buzz,HIGH);
stop();
}
else { digitalWrite(vib,LOW); //
digitalWrite(buzz,LOW);
}
}
long microsecondsToCentimeters(long microseconds) { // The speed of sound is 340 m/s or 29 microseconds per centimeter. // The ping travels out and back, so to find the distance of the // object we take half of the distance travelled. 15 | P a g e
return microseconds / 29 / 2; }
void verify(){ if(speedl<0) speedl=0; if(speedr<0) speedr=0; if(speedr>255) speedr=255; if(speedl>255) speedl=255; } void calib(){ int i=0; int valx,valy,minx=1023,miny=1023,maxx=0,maxy=0; while(i<1000){ valx=analogRead(sensex); valy=analogRead(sensey); maxx=fmax(maxx,valx); maxy=fmax(maxy,valy); minx=fmin(minx,valx); miny=fmin(miny,valy); i++;
16 | P a g e
delay(10); } theetax = (maxx-minx)/precision; theetay = (maxy-miny)/precision; meanx = 0.5*(maxx + minx); meany = 0.5*(maxy + miny); if(debug == 1){ Serial.print(maxx); Serial.print("
");
Serial.println(maxy); Serial.print("
");
Serial.print(minx); Serial.print("
");
Serial.println(miny); Serial.print("
");
Serial.print(theetax); Serial.print("
");
Serial.println(theetay); Serial.print(meanx); Serial.print("
");
Serial.println(meany); }
} void back(){
17 | P a g e
digitalWrite(lp,LOW); analogWrite(ln,(255)); digitalWrite(rp,LOW); analogWrite(rn,(255)); } void forward(){ digitalWrite(lp,HIGH); analogWrite(ln,0); digitalWrite(rp,HIGH); analogWrite(rn,0); } void right(){ digitalWrite(lp,LOW); analogWrite(ln,255); digitalWrite(rp,HIGH); analogWrite(rn,0); } void left(){ digitalWrite(lp,HIGH); analogWrite(ln,0); digitalWrite(rp,LOW); analogWrite(rn,255); } void stop(){ digitalWrite(lp,LOW);
18 | P a g e
analogWrite(ln,0); digitalWrite(rp,LOW); analogWrite(rn,0); }
19 | P a g e
RESULT
The walking stick is equipped with 4 ultrasonic sensors to tell the user if there are any obstructions on his right, left, front or if there is a potholes or stair in front. It was observed that 1 Arduino board drawing power through the USB cable from a laptop is not enough to power 4 ultrasonic sensors, 2 buzzers and 2 mobile vibrators. An adaptor should be used in such a case to power the arduino board. Due to unavailability of an adapter at the present moment 2 Arduino boards have been used to power the cane properly. The water sensor made using IC NE555 is working successfully.
APPLICATIONS This walking stick can bring a new lease of life for blind and old people. It is a means of independence for them. It will prove to be a useful tool to millions of blind people in navigating their environment with confidence and safety. It will allow then to travel where and when they want, and as such leads to self sufficiency. Independence and freedom to travel are so important to the quality of life of blind people that every blind person should have this cane.
20 | P a g e
PRECAUTIONS 1. Connections should be tight. 2. Make sure that all the components are getting the required amount of voltage so that they function properly. 3. The ultrasonic sensors must face the obstructions head on and not at an angle or they would not give correct values of distance.
LEARNING OUTCOME
I learnt how to use the Arduino board and program sensors, buzzers and vibrators using it. I also learnt the mechanism as to how the ultrasonic sensor works. It was also observed that 1 arduino board cannot power multiple ultrasonic sensors as one ultrasonic sensor requires 15mA when active, and Arduino can supply a maximum of 40mA current through each pin and a total of 200mA through all pins. Even then the sensor shows the correct value of distance in the serial monitor, but could not power the buzzer or vibrator properly, defeating the purpose for which it is being used. It was learnt how to make a simple water sensor using household components.
21 | P a g e
BIBLIOGRAPHY
1.
Getting Started with Arduino by Massimo Banzi
2.
Introduction to Arduino by Alan G. Smith
3.
www.arduino.com
4.
www.google.com
5.
www.wikipedia.org
22 | P a g e
