1. Hexapod Robot

This is a walking robot that has six legs and is controlled by ATmega128 CPU.

This chapter explains the structure, how to make, and walking method.(Note : Let

PCB faced to the floor. The actual product has PCB inside)

[Fig1] Shape of Hexapod robot

1.1 Operating principle of Hexapod Robot

This robot is constructed as shown in above[Fig1], and is designed to be

controlled remotely with the software or with joystick of playstation. User can

design this robot to perceive as well as avoid the obstacles in front.

[Fig2] Overall block diagram of Hexapod Robot

This robot has six legs, and each leg has three servo motors

(Totally 18 servo motors).

[Fig3]Servo Motors and legs

[Fig4] Relation between operating angles of servo motor and signal pulses

[Fig5]Bluetooth module for remote control

1.2 Introduction & description of each part of Hexapod robot.

The following images show the shape of hexapod robot. The PCB at the

bottom is the main board consisted of ATmega128 board.

(a) top view

(b) PCB View

[Fig 6] Overall shape of robot and PCB circuit

Zigbee wireless module is shown at the lower part of right side in above picture,

and this communicates with PC or Joystick remote controller. Turn on power to

operate the robot. A chargeable battery(6.2V) is equipped inside.

[Fig7] Power Switch

[Fig8] Charging Jack

[Fig8] is an input port to charge the battery of robot. The charger is an optional

item.

[Fig9] Control Board (ISP Port – 6 Pin Molex Connector)

[Fig9] is a port to download the program to download through printer port of PC.

Connect printer port cable to PC and then connect 6 pin connector to robot. Then turn

on power and download user’s program with downloading program.

[Fig10] Joystick for remote control

[Fig10] shows the joystick to control the robot remotely.

Refer to the datasheet for manuals.

1.3 Wiring diagram for Hexapod robot

Connect each servo motor to ATmega128 port. Connect PB and PC in turn. Refer

to the following picture. The wiring diagram is the same to round type or

rectangular Hexapod robot

[Fig11] Wiring diagram

2. Control of RC servo motor by port

2.1 Control of servo motor by using ATmega128 Port

[Fig12] shows the circuit diagram of ATmega128 used to the robot. Each servo

motor is connected to PortB, C, E and D.

----------------------------------------------------------------

PB0, PB1, PB2 / PB3, PB4, PB5 / PB6, PB7, PE2

No. 1 leg No. 2 leg No. 3 leg

- Front of Robot Back of Robot -

PC0, PC1, PC2 / PC3, PC4, PC5 / PC6, PC7, PD4

No. 4 leg No. 5 leg No. 6 leg -----------------------------------------------------------------

[Fig12] Basic circuit diagram of ATmega128

[Fig13] Connection of Servo Motor

[Fig14] Shape of Servo Motor

[Fig15] Relation between operation angle of servo motor and signal pulse

[Fig16] Assembly of leg joint with 3 servo motors

Assemble the leg part of robot. Assemble on leg in advance and proceed the

same procedures to the remaining legs. Set the axis of motor centered by

adjusting it to the right or left side. You can easily set the center by using the

control board.

[Fig17] Assembled shape of leg joint(Servo motor should be centered)

[Fig18] Assembly of sole

[Fig19] Assembled leg

[Fig20] Shape of control board used(External power switch connected)

Note: No.4 header pin by power switch connected is power input terminal. 2 pins

in horizon are for battery connection, and other 2 pins are power input(Connect

to electric jack terminal and check the polarity to assemble)

The above pictures show the leg connected with 3 servo motors. Connect the

legs to the body after each leg is completed. The following are programs to

experiment the operations.

[[ EX 1 ]] Program to operate servo motor[Fig 5.2] connected to ATmega128 at an angle

of from +90 to -90 degrees in evry one minute(Using of PORTB)

☞ Program /*********************************************

CodeWizardAVR V1.0.1.5g Standard PBtest.Program by ds2fwz Homepage : www.roboblock.co.kr/www.roboblock.com E-mail : ds2fwz@hotmail.com

Chip type : ATmega128

Clock frequency : 16.000000 MHz

*********************************************/

#include <mega128.h> // mega128.h includes header file #include <delay.h> // includes time delay function

// Declare your global variables here

void main(void)

// Declare your local variables here

unsigned int i, j, k ;

// Input/Output Ports initialization

DDRB=0xFF; // Port B output setting and default value HIGH signal PORTB=0xFF;

PORTB.0 = 0; /* Port default */

PORTB.1 = 0;

PORTB.2 = 0;

while(1)

delay_ms(1000); /* Approx. 1sec time delay */

for(i=0;i<15;i++) /* -90 Degree operation */

PORTB.0 = 1; /* Pulse ON */ PORTB.1 = 1; PORTB.2 = 1; delay_us(700); /* 0.7msec delay */

PORTB.0 = 0; /* Pulse OFF */ PORTB.1 = 0; PORTB.2 = 0; delay_ms(10); /* 10msec delay */

delay_ms(1000); /* Approx. 1sec time delay */

for(i=0;i<15;i++) /* +90 degree operation */

PORTB.0 = 1; /* Pulse ON */ PORTB.1 = 1; PORTB.2 = 1; delay_us(2300) /* 2.3msec delay */

PORTB.0 = 0; /* Pulse OFF */ PORTB.1 = 0; PORTB.2 = 0; delay_ms(10); /* 10msec delay */

} ; // End of while(1) // End of main()

}

[[ Ex 2 ]] [그림5.5]에Set three servo motors[Fig 5.5] connected to ATmega128 centered

and move the leg up and down.

☞ Program

#include <mega128.h>

#include <delay.h>

void initstep()

{

int i;

for(i=0;i<40;i++)

PORTB.0=1;

PORTB.1=1;

PORTB.2=1; //add--leg1

delay_us(1500); // 1.5ms pulse apply

PORTB.0=0;

PORTB.1=0;

PORTB.2=0; //add

delay_ms(10); // 10ms delay

}

void main(void)

// Declare your local variables here

// Port B initialization

// Func7=Out Func6=Out Func5=Out Func4=Out Func3=Out Func2=Out Func1=Out Func0=Out

// State7=0 State6=0 State5=0 State4=0 State3=0 State2=0 State1=0 State0=0

PORTB=0x00;

DDRB=0xFF;

// Port C initialization

// Func7=Out Func6=Out Func5=Out Func4=Out Func3=Out Func2=Out Func1=Out Func0=Out

// State7=0 State6=0 State5=0 State4=0 State3=0 State2=0 State1=0 State0=0

PORTC=0x00;

DDRC=0xFF;

// Port D initialization

// Func7=Out Func6=Out Func5=Out Func4=Out Func3=In Func2=In Func1=In Func0=In

// State7=0 State6=0 State5=0 State4=0 State3=T State2=T State1=T State0=T

PORTD=0x00;

DDRD=0xF0;

// Port E initialization

// Func7=In Func6=In Func5=In Func4=In Func3=Out Func2=Out Func1=In Func0=In

// State7=T State6=T State5=T State4=T State3=0 State2=0 State1=T State0=T

PORTE=0x00;

DDRE=0x0C;

while (1)

{

// Place your code here

initstep(); // Set to the center of motor

};

}

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