1

MASTER SHIFU

STUDENT NAME: Vikramadityan. M

ROBOT NAME: Master Shifu

COURSE NAME: Intelligent Machine

Design Lab

COURSE NUMBER: EEL 5666C

TA: Andy Gray,

Nick Cox

INSTRUCTORS: Dr. A. Antonio Arroyo,

Dr. Eric M. Schwartz

2

TABLE OF CONTENTS

1. Abstract…………………………………………………………….3

2. Introduction………………………………………………………4

3. Integrated System……………………………………………..5

4. Mobile Platform…………………………………………………8

5. Actuation …………………………………………………………..9

6. Sensors ……………………………………………………………..12

7. Behavior ……………………………………………………………14

8. Documentation …………………………………………………15

3

ABSTRACT Master Shifu.

The King of Kung Fu.

He looks small (yes he is a mouse in the movie!) but do not underestimate his powers. His petite

limbs and flexible body make him the Master of the art. He demonstrates his prowess using

chopsticks and leaves us all spellbound. Small and stunning, that’s what it’s all about!

4

INTRODUCTION

I liked the character of Master Shifu from the movie Kung Fu Panda. I had always wanted to make

a robot that walks on legs and not move on wheels. When I realized I could build one using

chopsticks, I could not resist. The design and construction of this robot is relatively simple and

cheap as well. The overall mass of the robot is also low. Micro servos will be used for movement

of the robot and IR sensors for obstacle detection. The system will be run on an Arduino Due

processor.

5

3. INTEGRATED SYSTEM

The robot is powered by Arduino Due processor. It will run 8 micro servo motors and 2 IR sensors.

The board will be powered by a 7.4V LiPo Battery which will be regulated down to 5V by a

regulator. At a given time, one micro servo will be run (temporarily) followed by sequential delays

to make the robot walk.

I soldered a regulator on a perf board to bring down the voltage to 5V from 7.4V, and got out the

output wires. This will power the servos.

Arduino

Due

µServo µServo µServo µServo

µServo µServo µServo µServo LiPo

Battery

IR IR

6

7

Fig 3.2

8

4. Mobile Platform

A rectangular frame will be the platform of the robot. This will accommodate the battery and the

board, owing to supports given at the bottom. At each of the joints of these supports and frames,

legs will be screwed in, and micro servos attached.

This kind of construction made by wooden slabs or chopsticks will reduce the overall weight of

the robot. Since only micro servos are used, it will hence be easier for movement. Also I realized

that, framed platform would look better than boxed ones for my robot!

Fig 4.1

9

5. ACTUATION

Servos are controlled by sending them a pulse of variable width. The control wire is used to send

this pulse. The parameters for this pulse are that it has a minimum pulse, a maximum pulse, and a

repetition rate. Given the rotation constraints of the servo, neutral is defined to be the position

where the servo has exactly the same amount of potential rotation in the clockwise direction as it

does in the counter clockwise direction. It is important to note that different servos will have

different constraints on their rotation but they all have a neutral position, and that position is always

around 1.5 milliseconds (ms).

Fig. 5.1

The angle is determined by the duration of a pulse that is applied to the control wire. This is called

Pulse width Modulation. The servo expects to see a pulse every 20 ms. The length of the pulse will

determine how far the motor turns.

When a pulse is sent to a servo that is less than 1.5 ms the servo rotates to a position and holds its

output shaft some number of degrees counterclockwise from the neutral point. When the pulse is

wider than 1.5 ms the opposite occurs. The minimal width and the maximum width of pulse that

will command the servo to turn to a valid position are functions of each servo. Different brands,

and even different servos of the same brand, will have different maximum and minimums.

Generally the minimum pulse will be about 1 ms wide and the maximum pulse will be 2 ms

wide.

10

Fig. 5.2

My robot will involve a total of 8 micro servos. Each of these are:

Size : 23x11x29 mm

Voltage : 3V to 6V DC

Weight: 9g / 0.32oz

Speed : 0.12 sec/60 (at 4.8V)

Torque : 1.6 kg-cm

Fig 5.3

Since only one micro servo will be in action at one given time and given that the Arduino Due can

function at 3.3V, minimum voltage can be fed in.

11

The robot consists of four legs. Each leg is made of two parts – the shoulder and the arm. Two

micro servos will be attached to each leg, one at the joint of the frame and the shoulder and the

other at that of shoulder and the arm. Thus the servo at the shoulder is first rotated followed by the

respective arm and this movement is repeated by the diagonally opposite leg. The same set is

performed by the remaining two legs. The rotation of the shoulder will help cover the height

required for the arm to lift and cover the horizontal distance.

12

6. SENSORS

Sharp IR sensors will be used for detecting obstacles. If the robot detects an obstacle, it will move

back walk away from it. The demo was done on the obstacle detection demo day. Here I used just

the shoulders of the robot and I had not attached the arms yet.

Fig 6.1

13

The coding used to control 4 motors is shown in the following screenshot.

14

7. BEHAVIOUR

The robot will be able to move forward when the micro servos in the front leg are activated,

followed by those on the diagonally opposite hind leg. The robot will have covered a certain

distance in one cycle, which is called gait.

For sideways movement, the micro servos on the forward leg is activated followed by the other

forward leg, after which the hind leg servos are activated.

The robot will have two PIR sensors mounted on both the forward legs which will detect obstacles

in its range and command the robot accordingly to avoid them.

The special sensor of my robot system will be the walking mechanism and the different movements

that are possible.

15

8. DOCUMENTATION

I used the following websites.

www.letsmakerobots.com

www.adafruit.com

www.arduino.cc

www.hobbyking.com