Hi-Tech Robotics Team 1

HEXAPOD

Hi-Tech Robotics Team 2

Hexapod:

A hexapod  is a robot that walks on six legs. Locomotion: hexapods are controlled by gaits, some of

which are,• Alternating tripod: 3 legs on the ground at a time• Quadruped• Crawl: move just one leg at a time

A-Pod Ziggy

Introduction

Hi-Tech Robotics Team 3

Hexapod: Hardware Components

Servo: Futaba S3003

Hi-Tech Robotics Team 4

Hexapod: Hardware Components

Microcontroller: ATMega32

Hi-Tech Robotics Team 5

Development Board: from Robokits.com

Hexapod: Hardware Components

Hi-Tech Robotics Team 6

Hexapod:

Compiler/Debugger: AVR Studio 5.0 Programming Language: Embedded C Simulation Software: Proteus (ISIS 7 Professional) Terminal Program: XCTU

Programming

Hi-Tech Robotics Team 7

Servo PWM code:

Using predefined PWMs of ATMega32• Timer 1, fast PWM mode• Clock freq. of 1MHz• PWM period set to 20ms by setting timer TOP(ICR1)

value at 20000

Shortcomings: Predefined PWM outputs available: 4 PWM channels required: 12

Version 1

Hi-Tech Robotics Team 8

Servo PWM code:

Using Bit-Bang technique:  manually implement PWM on any pin by repeatedly turning the pin on and off for the desired times.• Advantage: any digital output pin can be used. • Timer 1, CTC mode

All PWMs start at 0 count, duty cycles end in decreasing order of their pulse width.

Shortcomings: Results not satisfactory: lack of precision, unsuitable for hexapod gait programming

Version 2

Time(ms)Duty cycle 1 ends

All PWMs start 0

Duty cycle 2 ends

Duty cycle 3 ends

End of PWM cycle

Hi-Tech Robotics Team 9

Servo PWM code:

Using Bit-Banging• Timer 1, CTC mode

The next PWMs duty cycle starts at the end of first one’s Satisfactory results: good precision, suitable for hexapod gait programming

Version 3

Time(ms)Duty cycle 1 endsDuty cycle 2 starts

Duty cycle 1 starts start

0Duty cycle 2 endsDuty cycle 3 starts

Duty cycle 3 ends

End of PWM cycle

Hi-Tech Robotics Team 10

Hexapod: The complete code

Gait mechanism: Alternating tripod

12 PWM channels available on pins B0-7, D4-7 Motion commands transmitted from Laptop to Hexapod through serial cable

• Using USART feature of AtMega 32• Using XCTU terminal program installed in the laptop

Motion controls:• Standby• Push-up• Move Forward• Move Left• Move Right• Move Backward

Hi-Tech Robotics Team 11

Hexapod: A Glimpse

Hi-Tech Robotics Team 12

Presentation by: Himanshu Rao

THANK YOU