Hindi PGDT Project Reportsf

MICROCONTROLLER PROJECT

PS2 controlled omni bot

A PROJECT REPORT

submitted by

PRAVEEN(10BEE1058)

SAKSHI MISHRA(10BEE1076)

AKSHAY SINGH(10BEE1012)

SRIRAM PARAVASTU(10BEE1060)

in partial fulfillment for the award of the degree of

BACHELOR OF TECHNOLOGY

in

ELECTRICAL AND ELECTRONICS ENGINEERING

Problem statement: Build a wirelessly controlled OMNI directional bot. The wireless control is using a PS2(sony playstation 2) joystick. The bot should be maneuverable in any given direction according to the commands.

Introduction:

What is an Omni-Wheel Robot?

A robot that uses omni-wheels can move in any direction, at any angle, without rotating beforehand. If you want a robot that can straff, use an omni-wheel robot. If you want a robot that can spin while translating forward at the same heading, then you want this type of robot.

Omni wheels or poly wheels, similar to Mecanum wheels, are wheels with small discs around the circumference which are perpendicular to the rolling direction. The effect is that the wheel will roll with full force, but will also slide laterally with great ease. These wheels are often employed in holonomic drive systems.

Below are a few of the available omni-wheels on the market. The wheel size and diameter are dependent on things like expected robot speed, weight, etc.

Playstation 2 controller with receiver (2.4Ghz)

Theory behind:Holonomic vs Non-Holonomic Robots There are only two types of mobile robots, holonomic robots and non-holonomic robots. Non-holonomic robots are ones that cannot instantaneously move in any direction, such as a car. This type of robot has to perform a set of motions to change heading. For example, if you want your car to move sideways, you must perform a complex 'parallel parking' motion. For the car to turn, you must rotate the wheels and drive forward. This type of robot would have '1.5' degrees of freedom, meaning that it can move in both the X and Y direction, but requires complex motions to achieve the X direction.

A holonomic robot however can instantaneously move in any direction. It does not need to do any complex motions to achieve a particular heading. This type of robot would have 2 degrees of freedom in that it can move in both the X and Y plane freely. A robot arm typically is omni-directly too, with many more degrees of freedom.

Our bot employs three omni wheels in a triangular configuration.

Control of an Omni Wheel Robot

For an omni-wheel robot to translate at a particular angle, each wheel must rotate at a particular rotational velocity and direction. Since the robot is moving

http://www.societyofrobots.com/robot_arm_tutorial.shtml

at angles, it will need to do trigonometric calculations to determine these wheel speeds.

Angle control. For an omni-wheel robot to translate at a certain angle, each motor needs to go at a certain speed with relation to the others. The speed doesnt matter, just the ratios.

Motor speed. The faster the motors go, the faster the robot goes.

Rotational control. For an omni-wheel robot to rotate at some particular speed, it must add or subtract equally from the motor speed of each motor.

Maximum motor speed. Motors can only go so fast, so when you do ratios, and rotational control additions, you must make sure that you are not commanding a motor to go faster than it can.

Methodology (hardware setup):

Block diagram:

SCHEMATIC:

FLOWCHART:

NO

YES

START

Initialize the motor and wireless controller receiver

Check if the connection between the microcontroller

and receiver is established

Read the command from the controller

connector

Check the

Next command

ALGORITHM:

1. Start2. Initialize the pins as output and input according to the motor driver and ps2

receiver connections.3. Initialize connection with the PS2 controller and enable the motors.4. If a link between the ps2 controller and the receiver is established, read

data from the ps2 controller.

connector

Process the command

according to the button

programmed in subroutines

Button X-120 deg rotation

Button -240 deg rotation

STOP

5. Decode The data read from the controller using the datasheet of the controller, which shows the timing diagrams for the data/clock and also the data sent for various button configuration. As shown below:byte enter_config[]={0x01,0x43,0x00,0x01,0x00};byte set_mode[]={0x01,0x44,0x00,0x01,0x03,0x00,0x00,0x00,0x00};byte set_bytes_large[]={0x01,0x4F,0x00,0xFF,0xFF,0x03,0x00,0x00,0x00};byte exit_config[]={0x01,0x43,0x00,0x00,0x5A,0x5A,0x5A,0x5A,0x5A};byte enable_rumble[]={0x01,0x4D,0x00,0x00,0x01};byte type_read[]={0x01,0x45,0x00,0x5A,0x5A,0x5A,0x5A,0x5A,0x5A};

6. Control the bot according to the button pressed on the controller. All the actions for a specific button is configurable. Say, if the up arrow button is pressed , command the bot to move forward and if the down arrow is pressed, command the bot to move backward and so on… based on the picture below:

The drive mechanism is explained in the picture below:

7. On exit,Close the controller connections. Turn of all the motors.

8. stop

CODE:

The Arduino code for the bot is below.

#include <PS2X_lib.h>

//Looking from the back of the omni bot

//P: +ve; N:-ve; Clockwise +ve

#define MFP 1 //motor front +ve terminal

#define MFN 3 //motor front -ve terminal

#define MLP 4 // motor left

#define MLN 5

#define MRP 6 //motor right

#define MRN 7

//EN pins. currently not used but used in case the velocities of the motors have to be varied using PWM

#define MF_EN 9

#define ML_EN 10

#define MR_EN 11

PS2X ps2x; // create PS2 Controller Class

int error = 0; // error b/w the link between the PS2 controller and receiver

byte type = 0; // type of the controller

byte vibrate = 0; // Vibration of rumble motors

void setup(){

Serial.begin(57600); // init serial with 57600 baud rate for debugging info

pinMode(MFP,OUTPUT);

pinMode(MFN,OUTPUT);

pinMode(MLP,OUTPUT);

pinMode(MLN,OUTPUT);

pinMode(MRP,OUTPUT);

pinMode(MRN,OUTPUT);

pinMode(MF_EN,OUTPUT);

pinMode(ML_EN,OUTPUT);

pinMode(MR_EN,OUTPUT);

error = ps2x.config_gamepad(2,12,8,13); //setup GamePad(clock, command, attention, data) pins, check for error

if(error == 0){

Serial.println("LInk established successfully");

}

else if(error == 1)

Serial.println("No controller found, ");

else if(error == 2)

Serial.println("Controller found but not accepting commands");

//Serial.print(ps2x.Analog(1), HEX);

type = ps2x.readType();

switch(type) {

case 0:

Serial.println("Unknown Controller type");

break;

case 1:

Serial.println("DualShock Controller Found");

break;

}

//ps2x.enableRumble(); //enable rumble vibration motors

if(!ps2x.enablePressures()) //enable reading the pressure values from the buttons.

Serial.println("Controller refusing Pressures mode, may not support it.");

}

void loop(){

if(error != 0) //skip loop if no controller found

return;

{ //DualShock Controller

// ps2x.read_gamepad(false, vibrate); //read controller and set large motor to spin at 'vibrate' speed

ps2x.read_gamepad();

if(ps2x.Button(PSB_START)) //will be TRUE as long as button is pressed

Serial.println("Start is being held");

if(ps2x.Button(PSB_SELECT))

Serial.println("Select is being held");

if(ps2x.Button(PSB_PAD_UP)) { //will be TRUE as long as button is pressed

forward();

}

if(ps2x.Button(PSB_PAD_RIGHT)){

clockwise();

}

if(ps2x.Button(PSB_PAD_LEFT)){

anticlockwise();

}

if(ps2x.Button(PSB_PAD_DOWN)){

backward();

}

if(ps2x.ButtonPressed(PSB_PINK))

{ twofortydegrees();

clockwise();

twofortydegrees();

clockwise();

twofortydegrees();

}

if(ps2x.ButtonPressed(PSB_BLUE))

{

anticlockwise();

onetwentydegrees();

anticlockwise();

onetwentydegrees();

anticlockwise();

onetwentydegrees();

}

vibrate = ps2x.Analog(PSAB_BLUE); //this will set the large motor vibrate speed based on

//how hard you press the blue (X) button

if (ps2x.NewButtonState()) //will be TRUE if any button changes state (on to off, or off to on)

{

if(ps2x.Button(PSB_L3))

Serial.println("L3 pressed");

if(ps2x.Button(PSB_R3))

Serial.println("R3 pressed");

if(ps2x.Button(PSB_L2))

Serial.println("L2 pressed");

if(ps2x.Button(PSB_R2))

Serial.println("R2 pressed");

if(ps2x.Button(PSB_GREEN))

twofortydegrees();

//Serial.println("Triangle pressed");

}

if(ps2x.ButtonPressed(PSB_RED)) //will be TRUE if button was JUST pressed

onetwentydegrees();

//if(ps2x.ButtonReleased(PSB_PINK)) //will be TRUE if button was JUST released

//Serial.println("Square just released");

// Serial.println("X just changed");

if(ps2x.Button(PSB_L1) || ps2x.Button(PSB_R1)) // print stick values if either is TRUE

{

Serial.print("Stick Values:");

Serial.print(ps2x.Analog(PSS_LY), DEC); //Left stick, Y axis. Other options: LX, RY, RX

Serial.print(",");

Serial.print(ps2x.Analog(PSS_LX), DEC);

Serial.print(",");

Serial.print(ps2x.Analog(PSS_RY), DEC);

Serial.print(",");

Serial.println(ps2x.Analog(PSS_RX), DEC);

}

}

//delay(50);

//

}

// function to command the omni bot to move forward

void forward()

{Serial.println("going forward");

digitalWrite(MR_EN,1);

digitalWrite(ML_EN,1);

digitalWrite(MRP,1);

digitalWrite(MRN,0);

digitalWrite(MLP,0);

digitalWrite(MLN,1);

delay(200);



}

//function to command the omni bot to move backward

void backward()

{Serial.println("going backward");







delay(200);



}

// function to command the omni bot to rotate clockwise

void clockwise()

{







delay(200);



}

//function to command the omni bot to rotate anti-clockwise

void anticlockwise()

{







delay(200);



}

//function to command the omni bot to move right

void rightturn()

{

digitalWrite(MFP,0);

digitalWrite(MFN,1);

digitalWrite(MF_EN,1);







delay(200);



delay(20);


}

//function to command the omni bot to move left

void leftturn()

{










delay(200);



delay(20);


}

//functionn to command the bot to move at 240degrees

void twofortydegrees()

{







delay(200);



}

//function to move the bot at 120degrees

void onetwentydegrees()

{







delay(200);



}

Future Enhancements:

• 1.Precise direction control.

2.Mixed Linear and Angular Movement

Should the robot need to rotate its body while moving

towards the ball, linear and angular velocity can be combined

by calculating the sum of both contributions

DATA SHEETS (PIN OUT DIAGRAMS ) OF ICs USED:

Overview

The Arduino Uno is a microcontroller board based on the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter.

Summary

Microcontroller ATmega328Operating Voltage 5VInput Voltage (recommended) 7-12VInput Voltage (limits) 6-20VDigital I/O Pins 14 (of which 6 provide PWM output)Analog Input Pins 6DC Current per I/O Pin 40 mADC Current for 3.3V Pin 50 mAFlash Memory 32 KB (ATmega328) of which 0.5 KB used by bootloaderSRAM 2 KB (ATmega328)EEPROM 1 KB (ATmega328)Clock Speed 16 MHz

REFERENCES:

http://en.wikipedia.org/wiki/Omni_wheel

http://www.billporter.info/2011/03/27/arduino-playstation-2-controller-library-troubleshooting-guide/

http://store.curiousinventor.com/guides/PS2/

http://nex-robotics.com

http://store.curiousinventor.com/guides/PS2/



http://en.wikipedia.org/wiki/Omni_wheel

Documents

Hindi PGDT Project Reportsf