Feeding system for disabled report

Feeding System for Disabled
Submitted by Group 2
Mayank Awasthi 2006033
Md Sadhiq 2006034
Anand Kumar 2006076

Under the supervision of
Mr. Awadesh Kumar Singh
Design Project (MN-302)

Instructors: Prof. Amit Ray
Dr. Puneet Tandon
Dr. M.K. Roy

Pandit Dwaraka Prasad Mishra Indian
Institute of Information Technology Design
and Manufacturing, Jabalpur

i

DEDICATION

To
Our Project Guide,
Faculty members,
Workshop, Lab Assistants
&
Seniors
For Letting Us to Fulfill
Our Dreams

ii

ACKNOWLEDGEMENT

First of all, we would like to express our sincere thanks to our supervisor Mr.
Awadesh Kumar Singh for his intellectual guidance, continuous interest,
generous support, infinite patience, and constant encouragement throughout this
project work. He has devoted his valuable time to discuss this project, his
expertise and broad knowledge in Engineering Design played a major role in the
realization of this work. We appreciate Mr. Awadesh Kumar Singh for his
confidence boosting start up to our project work and encouragement in creative
endeavors.

We especially appreciate the company of our classmates, seniors, workshop &
lab assistants and who have made useful to this work by way of discussions and
suggestions from time to time.

Group II

Mayank Awasthi (2006033)

Md Sadhiq (2006034)

Anand Kumar (2006076)

iii

ABSTRACT

People with disabilities constitute a large percentage of the population, including
those who have difficulty using their hands and arms to control and manipulate
their environment. In order to live their daily lives, they must be under constant
supervision. Often, this requirement is not met because such care is hard to find
due to lack of assistance or for financial reasons. If a feeding system could be
designed and manufactured for these people, the need for constant supervision
could be reduced drastically. The feeding system could assist them in feeding
themselves. It would rebuild confidence and self-esteem lost in the depth of
illness.

iv

CONTENTS

I. Objective ……………….................1

II. Research …………………………...2

III. Technical Details ……………………4

IV. Fabrication Process ………………...8

V. Working …………………………… 12

VI. Costing ……………………………….13

VII. Conclusion …………………………...16

VIII. References …………………………17

IX. Appendix …………………………….

i. Microcontroller Program
ii. Product Photos

v

Objective

The aim of this project is to design a lightweight, easy to use, and low cost
robotic feeding arm, which would act as an extension for the affected people to
regain their independence from disease. The functional requirement of the device
is that it should allow the user to manipulate a feeding utensil and to bring the
liquid to the mouth.

We have divided this project in two phases:

Phase I: In last semester we did the CAD modeling & simulation of our design &
also completed a working prototype of our design.

Phase II: In this semester we have done the fabrication and microcontroller
programming for servo controlled precise movement of the arm.

vi

Research

There are basically two robotic arms out on the market currently, the Helping
Hand and the MANUS. The Helping Hand was produced by Kinetic Rehab
Instruments (KRI), they have since gone out of business. It is controlled by a
joystick interface and has four degrees of freedom not including the gripper. The
MANUS is produced by a company called Exact Dynamics. It is controlled by a
sixteen key, keypad interface and has seven degrees of freedom.

The marketing difficulties are the same for both of these devices. Those who
have heard about robotic devices aren’t convinced about the benefits and the
usability of the devices. Therefore potential users of a robotic arm are finding
alternative solutions. For example: smart homes, environmental control systems
and human assistants. In addition to high cost, another problem is that most
people have never heard of rehabilitation robotics. A better market strategy is
necessary to convince potential users to choose robotics as a solution.

Requirements:

 The manipulator should be robust, light weight, modular, easy-to-operate
and safe.

 It should be cost effective.

 The arm’s workspace should be similar to the arm of an average man
having aesthetic look.

vii

Technical Details:

The basic key elements of the configuration are:

 Degree of freedom
 Linkages
 Transmission
 Actuation HS-322HD servo motors
 ATMEL 89S52 Microcontroller
 User Interface(through Computer)

Servo Motors:

Servo motors are used in closed loop control systems in which work is the control
variable. The digital servo motor controller directs operation of the servo motor by
sending velocity command signals to the amplifier, which drives the servo motor.
An integral feedback device (resolver) or devices (encoder and tachometer) are
either incorporated within the servo motor or are remotely mounted, often on the
load itself. These provide the servo motor's position and velocity feedback that
the controller compares to its programmed motion profile and uses to alter its
velocity signal. Servo motors feature a motion profile, which is a set of
instructions programmed into the controller that defines the servo motor
operation in terms of time, position, and velocity. The ability of the servo motor to
adjust to differences between the motion profile and feedback signals depends
greatly upon the type of controls and servo motors used.

Principle strengths of Servo Motor:
1. High performance
2. Small size
3. Wide variety of components
4. High speeds available with specialized controls

Principle weaknesses:
1. Slightly higher cost
2. High performance limited by controls
3. High speed torque limited by commutator or electronics

viii

Functioning of servo Motor:

Block Diagram of servo control

HS-322HD Servo Motors Specifications:

This servo comes with mounting hardware, mounting grommets, and 4 servo
horns. The HS-322HD servo has heavy duty gears for smoother operation and
longer life when compared to normal servos. This servo has a Hitech/JR
connector which mates directly with a 0.1" 3-pin header. The servo spline has 24
teeth and mates with Hitec compatible accessories.

Specifications
Voltage
Operating Speed Output Torque Weight
Range
0.19sec/60 degrees at 3kg.cm (41.6oz.in) at 43.0g
4.8V - 6V
4.8V 4.8V (1.51oz)

Wire Color Meaning

On all Hitec servos the Black wire is 'ground', the Red wire (center wire) is
'power', and the yellow (third) wire is 'signal'.

ix

How to communicate the angle at which the servo should turn

The control wire is used to communicate the angle. The angle is determined by
the duration of a pulse that is applied to the control wire. This is called Pulse
Coded Modulation. The servo expects to see a pulse every 20 milliseconds (.02
seconds). The length of the pulse will determine how far the motor turns. A 1.5
millisecond pulse, for example, will make the motor turn to the 90 degree position
(often called the neutral position). If the pulse is shorter than 1.5 ms, then the
motor will turn the shaft to closer to 0 degress. If the pulse is longer than 1.5ms,
the shaft turns closer to 180 degress.

As seen in the picture, the duration of the pulse dictates the angle of the output
shaft (shown as the green circle with the arrow).

ATMEL 89S52 8-bit Microcontroller:
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with
8K
bytes of in-system programmable Flash memory. The on-chip Flash allows the
program memory to be reprogrammed in-system or by a conventional nonvolatile
memory programmer.

By combining a versatile 8-bit CPU with in-system programmable Flash on
a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which
provides a
highly-flexible and cost-effective solution to many embedded control applications.

x

The AT89S52 provides the following standard features: 8K bytes of Flash, 256
bytes
of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit
timer/counters, a
six-vector two-level interrupt architecture, a full duplex serial port, on-chip
oscillator,
and clock circuitry.

PIN Configuration

Pin configuration of ATMEL 89S52

xi

Dimension:
Base board 18’’*12’’*2’’

Base arm 2.5’’*2.5’’*6’’

Shoulder Link 11’’

Spoon Length 5’’

Fabrication Process
Fabrication process involved two modules
 Mechanical design
 Circuit design
 User Interface

Mechanical Design:

Base:

 The base is a key point in our design of feeding system. In the base we
have used a HS-322HD servo motor which is used to rotate the whole
system.
 The whole arm is connected to the spindle of the base motor using ball
bearings to minimize the load on the spindle and for the smooth
rotation of the arm. Moreover it would minimize the vibrations of the
system during rotation.

xii

Shoulder Link:

 The shoulder assembly consists of a link which is controlled by a HS-
322HD Servo Motor.
 This shoulder link has another servo motor connected to one of the ends
to control the spoon motion. Due the weight of the servo motor shoulder is
unable to with stand in its position. So a counter balancing mechanism is
used to minimize the gravity effect.

Feeding Spoon:

 The feeding spoon is controlled by a HS-322HD servo motor which is
fixed at the end of the shoulder link.
 This spoon is used to lift the food items (mainly liquids) from the bowl
which is placed on the table at a fixed location.

xiii

Circuit Design:
In our circuit design we have used two ATMEL 89S52 microcontrollers to control
the three servo motors. One microcontroller acts as a master and other one as
the slave.
The master is used to control the motion of base and the spoon. And the slave is
used to control the shoulder link. These two microcontrollers are working on the
principle of parallel processing. It use of more than one CPU or processor or
microcontrollers to execute a program or multiple programs. Ideally, parallel
processing makes programs run faster because there are more engines (CPUs
or cores) running it.

Circuit Description/Diagram:

 The upper 4 bits of the master is connected to the lower 4 bits of the slave
as shown in the circuit diagram.
 The base motor gets the signal from the first bit of the port 1(master) and
the motor which is fixed at the spoon gets signal from second bit of the
port1.
 The shoulder link motor gets the signal from the first bit of port 1(slave) as
shown.
 Bits no. 10,11,12,13 are connected to the bits of RS-232 port to get the
input from the Computer.

xiv

Microcontroller Programming: We have done the microcontroller program to
move the servo motors at the required angle. For code see appendix.

User Interface:
We have provided a computerized user interface where a certain number code
represents the certain motion.

For base motion:
2_1: Represent initial position.
2_2: Rotate 20 deg rotation from initial.
2_3: Again 20 deg rotation.
.
.
So on till
2_9.

xv

For Shoulder link motion:
.
.
So on till
1_9.

For spoon motion:
.
.
.
So on till
3_9.

Working:
 Initially, the arm is at its fixed position as in fig.1
 The base is rotated to move the arm near the bowl according to user
input, then the shoulder joint comes into action which places the spoon
like structure inside the bowl (fig.2) according to user input.
 The spoon is rotated to lift the liquid food (fig.3)
 Then, base is rotated to move the arm towards the user; then again
shoulder joint comes into action which moves the spoon towards the
user’s mouth (fig.4)

xvi

Fig.1 Fig.2

Fig.3 Fig.4

ADAMS Simulation

xvii

Costing:
Manufacturing Cost (excluding Labour cost + R&D )
S.NO Parts name Price(Rs.)/unit Quantity Price(Rs.)
1 Servomotor 1500 3 4500
Hitec HS-322
HD
2 Microcontroller kit 2000 2 4000
ATMEL 89S52
3 Transformer 100 2 200
4 RS232 Cable 200 1 200
5. Acrylic sheet 300/Sq ft. 1 sq. ft. 300
6 Ball Bearing 10 4 40
7. Spoon 10 1 10
8 Base Board 100 1 100
9. Miscellaneous 250 --- 250
(Glue,Nuts,alumi
num strip ,cables,
etc)
TOTAL Rs. 9600/-

 The prices stated are approximate depending upon market and quantity
purchased.

 On large scale production, the price of the final product can be reduced
further. The cost of the product can come up to Rs.6000-7000.

xviii

Conclusion:

 The vibration occurring due to the servomotor limitation is a hurdle in
smooth rotation of the arm which need to be addressed carefully.

 Mechanical structure proposed and the capabilities of servomotors are not
in full coordination, so some changes in structure is required.

 More advanced microcontroller for better impulse sending and retrieving.

 Use of sensors for detecting the food level and position of user.

 Separate user interface in place of current interface for better ergonomics.

 The angle rotation is 20 degree per pulse which should be further
minimized up to 5 degree for better controlled movement of arm.

 Aesthetic look have great scope to work upon and position of the circuit
and bowl need to be adjusted more precisely.

 For picking food objects as well as liquid, grippers/other mechanism can
be proposed to handle different types of food.

xix

References:
http://www.robokits.com

http://www.thinkindialab.com

http://www.asel.udel.edu/robotics


http://www.google.com


http://www.asel.udel.edu/resna-sig13

http://www.esnips.com

xx

APPENDIX:

i. Microcontroller Program:
#include<at89x52.h>
#define servo1 P1_1
#define servo2 P1_2
#define servo3 P1_3

unsigned char select,angle,ptr=0;

void timer1_ovf(void) interrupt 3
{
TH1=0xB7; //20msec //0xCA; //15 msec interrupt
TL1=0xFD; //0x00;
switch(select)
{
case '1': servo1=1;break; //servo on pulse

}
TR0=1;
P0_4=~P0_4;
}
void timer0_ovf(void) interrupt 1
{
switch(angle)
{
case '1':TH0=0xFD;TL0=0xD8;break;
case '2':TH0=0xFD;TL0=0x1D;break;
case '3':TH0=0xFC;TL0=0x62;break;
case '4':TH0=0xFB;TL0=0xA7;break;
case '5':TH0=0xFA;TL0=0xEC;break;
case '6':TH0=0xFA;TL0=0x31;break;
case '7':TH0=0xF9;TL0=0x76;break;
case '8':TH0=0xF8;TL0=0xBB;break;
case '9':TH0=0xF7;TL0=0xFA;break;

}

switch(select)
{

}

xxi

TR0=0;
}
void UARTInit(void)
{
SCON=0X50;
T2CON=0X30;
RCAP2H=0XFF;
RCAP2L=0XFA; //57600 instruction per second
TH2=0XFF;
TL2=0XFA;
ES = 1;
TR2 = 1;
}
void IRQ_UartGet(void) interrupt 4
{
unsigned char i;

if(RI==1)
{
RI = 0;
i = SBUF;
if(ptr==0)
{select=i;
ptr++; ET1=0;
ET0=0;
}
else
{
angle=i;
ptr=0;
ET1=1;
ET0=1;
}
}
}

void main()
{
TMOD=0x11;
ET1=1;
ET0=1;
TH1=0xB7;
TL1=0xFE;
TR1=1;
TH0=0xFA; //shaft position to 0 1500 usec
TL0=0x9A;
UARTInit();
EA=1;
P1=0xF0;
//Led=0;
P3=0xFF;
while(1){
}
}

xxii

ii. Product Photos:

Circuit Connection

Full View of the Product

xxiii

Feeding system for disabled report

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