During normal walking motion, our feet absorb the shock of impacting the ground by rolling inwards towards the center of the body distributing weight evenly across the entire foot. Unfortunately, only a quarter of the populations are considered "neutral" footed, without any noticeable problems with their gait. Half the populations suffer from over-pronation, where the feet roll too far inwards causing undue stress to the arch of the foot. The remaining quarter suffer from the opposite problem, supination. Problems associated with incorrect walking form include knee/ankle injuries and foot pain.
We hope our project will help podiatrist analyze the problems associated with over-pronation/supination by providing an affordable data measurement/logging device. Using an integrated SD card, each patient would be able to provide weeks’ worth of data to the podiatrist, capturing the many activities we encounter throughout the day. Treatment and custom orthopedics can then be personalized.
We imagine our project would also have sports applications, as the data can help improve the form of the user.
LIST OF FIGURE
FIG 1 Neutral pronation 14
FIG 2Over pronation 15
FIG 3 Under-pronation 15
FIG 4 Right foot (a) Pronated, (b) Neutral and (c) Supinated 16
FIG 5 Effect of pronation 16
FIG 6 Shoe type 17
FIG 7 Simplified block diagram 19
FIG 8 Sequential state machine 22
FIG 9 Atmel Corporation 24
FIG 10 pin diagram of ATMEGA644 26
FIG 11 Package view of atmega644 27
FIG 12 Pin diagram of quadpack atmega644 28
FIG 13 Quad package view of atmega644 28
FIG 14 Power circuit 30
FIG 15 Power ic 7805 31
FIG 16 Schematic of power ic 7805 32
FIG 17 Crystal circuit 32
FIG 18 Basic reset circuit 33
FIG 19 Reset circuit interface with ATMEGA644 34
FIG 20 Essential hardware interface of ATMEGA644 35
FIG 21 Working principle of accelerometer 36
FIG 22 Gravitation force 37
FIG 23 a) Spring mass system without acceleration 37
FIG 24 Function block diameter of MMA7361L ACCELEROMETER 39
FIG 25 Pin diagram of MMA7361L 39
FIG 26 Accelerometer MMA7361L module 41
FIG 27 Working principle of gyroscope 43
FIG 28 Gyroscope module 44
FIG 29 Schematic of FSR 45
FIG 30 Structure of FSR 46
FIG 31 FSR datasheet characteristic 47
FIG 32 FSR schematic 47
FIG 33 SD card module 48
FIG 34various sizes of SD card 49
FIG 35 Interfacing module with controller 51
FIG 36 Complete circuit diagram 53
FIG 37 Simulating snapshot 54
FIG 38 hardware circuit view 56
FIG 39 Hardware circuit PCB bottom view 57
‘
LIST OF TABLE
TABLE 1 Pin description of MMA7361L 35
TABLE 2 Specification of accelerometer MMA7361L 37
‘
LIST OF ABBREVIATIONS
FSR Force sensitive resistor
LCD Liquid crystal display
SD Secure digital
ADC Analog digital converter
MUX Multiplexer
AVR Advance virtual RISC machine
RISC Reduced instruction set computer
CMOS Complementary metal oxide semiconductor
USART Universal synchronous asynchronous receiver transmitter
MIPS Microprocessor without interlocked pipeline stages
EEPROM Electrically erasable programmable read only memory
SRAM Static random access memory
PWM Pulse width modulation
SPI Serial peripheral interface
DIP Dual in line package
QFT Quad flat package
DC Direct current
PF Power factor
IC Integrated circuit
PTF polymer thick film
MMC Multimedia card
SDA SD card association
DRM Digital right management
TABLE OF CONTENTS
ABSTRACT 7
LIST OF FIGURE 8
LIST OF TABLE 9
LIST OF ABBREVIATIONS 10
CHAPTER 1 INTRODUCTION 14
1.1 Introduction of Pronation 14
1.2 Types of Pronation 14
1.2.1 Neutral Pronation 14
1.2.2 Over-pronation 15
1.2.3 Under-pronation 15
1.3 Effect of Pronation 16
1.3.1 Effect of Over and Under Pronation 16
1.3.2 Prevention of Effects of Pronation 17
1.3.2.1 Orthotics 17
1.3.2.2 Shoe Type 17
1.3.2.3 Taping 17
1.3.2.4 Shoe-lacing Patterns 18
1.4 Objective 18
1.5 Scope 18
CHAPTER 2 IMPLEMENTATION OF PROJECT 19
2.1 Block Diagram 19
2.2 High Level Design 19
2.2.1 Data Measurement 19
2.2.2 Data Processing 20
2.2.3 Data StorageOutput 20
2.3 Software Design 20
2.3.1 Maintains Program and Control Flow 20
2.3.2 Data Collection 21
2.3.2.1 Data Monitoring 21
2.3.2.2 Step Detection Processing 21
2.3.2.3 Pronation Detection 21
2.3.2.4 Writing to SD Card 21
2.4 What is State Machine? 21
2.4.1 Advantages of State Machine 22
2.4.2 Drawback of State Machine 23
2.5 Hardware Design 23
CHAPTER 3 ATMEL ATMEGA644 TARGET BOARD 24
In hardware section main controller target board contain following different block are: 24
3.1 ATMEGA644 controller 24
3.1.1 About ‘ATMEL Corporation’ 24
3.2 Atmega644 Micro-Controller Features 25
3.3 Packaging 26
3.3.1 Pin diagram of DIP-40pin ATMEGA644 controller 26
3.3.2 QFP-44 pin ATMEGA644 controller 28
3.4 Pin Descriptions 29
3.5 Power supply circuit 30
3.5.1 IC 7805 (Voltage Regulator) 31
3.5.1.1 General Description of IC 7805: 31
3.5.1.2 Features of IC 7805: 32
3.6 Crystal oscillator circuit 32
3.7 Reset circuit 33
3.7.1 Description 33
3.7.2 Reset circuit with ATMEGA644 33
3.8 Minimum hardware configuration of ATMEGA644 34
CHAPTER 4 ACCELEROMETER 36
4.1 Working Principle: 36
4.1.1 What is G-force? 37
4.2 Structure of Accelerometer 37
4.3 free-scale MMA7361L accelerometer 38
4.3.1 Features 38
4.3.2 Function block diagram of MMA7361L 39
4.3.3 Pin description 39
4.3.4 Application 40
4.3.5 Accelerometer module 41
4.3.6 Specifications 41
CHAPTER 5Gyroscope 43
5.1 Description 43
5.2 Structure of gyroscope 43
5.3 Gyro + accelerometer sensor, 3 axis based on MPU6050 44
5.3.1 Features 44
CHAPTER 6 Force Sensitive Resistor 45
6.1 What is force sensitive resistor? 45
6.2 Features and Benefits 45
6.3 Typical Schematic 45
6.4 Structure of FSR 46
6.5 Interfacing with ATMEGA644 47
CHAPTER 7 SD Card Module 48
7.1 Description 48
7.2 Secure Digital (SD Card) 49
7.2.1 Features of SD Card 50
7.3 SD Card Module Interface 51
7.4 Serial Peripheral Interface (SPI) 52
CHAPTER 8 HARDWARE CIRCUIT 53
8.1 Circuit diagram 53
8.2 Simulating circuit in PROTEUS 54
8.3 Hardware circuit view 56
8.4 Hardware circuit PCB bottom view 57
CONCLUSION 58
REFERENCE 58
‘?CHAPTER 1 INTRODUCTION
1.1 Introduction of Pronation
Pronation is the inward roll of the foot while running or walking. Another way to look at pronation instead in terms of the degree of the inward roll is in terms of where the foot pushes off at the end of each step or at the end of the gait cycle.
Pronation occurs at the joint below the ankle, the ‘subtalar’ joint. It describes the inward rolling motion of the foot just after it lands on the ground. This moment called initial contact which is part of the stance phase of the gait cycle.
1.2 Types of Pronation
There are three main type of pronation in human gait
‘ Neutral pronation(eversion)
‘ Over-pronation
‘ Under-pronation(supination)
While both over-pronation and under-pronation occur while walking and standing, they are usually more pronounced and the effects amplified while running.
1.2.1 Neutral Pronation
Some pronation also called EVERSION is neutral in the body’s regular movement. Neutral pronation occurs when the foot experiences a normal, healthy amount of pronation instead of over-pronation or under-pronation. In healthy movement more of the toe area will be used when pushing off than in unhealthy movement. In neutral pronation the weight distributes fairly evenly among all of the toes and second toe which are better adapted to handle more of the load.
FIG 1 Neutral pronation
1.2.2 Over-pronation
Those who over-pronate tend to push off almost completely from the big toe and second toe. As a result the shock from the foot’s impact dose not spread evenly throughout the foot and ankle has trouble stabilizing the rest of body. Addition, an unnatural angle form between the foot and ankle and the foot splays out abnormally.
FIG 2Over pronation
It is common even for people who pronate normally to have some angle betweenthe foot and ankle, but not to the extent seen in those who over-pronate. In normal pronation weight distributes evenly throughout the foot.
1.2.3 Under-pronation
It is also called as SUPINATION, occurs when the foot impacts the ground and there is not enough of an ‘inward roll’ in the foot’s motion. The weight of the body is not transferred at all to the big toe forcing the outside of the foot and the smaller toe which cannot handle the stress as well to take the majority of the weight instead.
FIG 3 Under-pronation
Following foot-prints shows the all position of three kind of pronation neutral, over-pronation and under-pronation during the walking or running.
FIG 4 Right foot (a) Pronated, (b) Neutral and (c) Supinated
1.3 Effect of Pronation
Neutral pronation also called as ‘EVERSION’ is natural in the body’s regular movement however over-pronation and under-pronation can be potentially harmful.
1.3.1 Effect of Over and Under Pronation
Over-pronation may have effects on the lower legs such as increased rotation of the tibia, which may result in lower leg or knee problems. Over-pronation is usually associated with many overuse injuries in running including medial tibia stress syndrome, or shin splints and knee pain.
FIG 5 Effect of pronation
1.3.2 Prevention of Effects of Pronation
1.3.2.1 Orthotics
Wearing supportive orthotics in the shoe is a method commonly implemented to treat many common running injuries that are thought to be associated with pronation. 262 out of the 500 runners involved in the study either had great improvement or complete healing of the injury after wearing the orthotics. The most effective treatment of injuries came in treating symptoms that resulted from unusual biomechanics within the body such as over-pronation. An added advantage of orthotics is that they often allow the runner to continue to participate in athletic activity and avoid other treatment options that could be potentially costly and time consuming.
1.3.2.2 Shoe Type
Foot pronation tends to increase in runners as mileage also increases potentially increasing the risk for injury.Motion control shoes are a specific type of running shoe designed to limit these excessive foot motions. They have been shown to significantly reduce the amount of plantar force (a force generated by excess pronation) when compared to normal footwear used in running. Motion control and stability shoes have increased medial support which may increase stability to the foot and leg and lower the amount of pronation in the foot.
FIG 6 Shoe type
1.3.2.3 Taping
Certain methods of taping the foot and leg have also been shown to be effective in preventing over-pronation. A taping procedure known as the Low-Dye taping technique was shown to be effective in controlling pronation during both movement and standing.
1.3.2.4 Shoe-lacing Patterns
Specific patterns of lacing running shoes have also been shown to help reduce pronation. When the highest number of eyelets in the shoe is used for lacing and the shoes are tied as tight as possible pronation is significantly decreased.
Under-pronatordoes best in a neutral-cushioned shoe that encourages a more natural foot motion. ‘Since under-pronators feet do not roll inward like over-pronators, support is not necessarily needed to correct supination as it is to correct over-pronation. Instead extra cushioning in the shoe is the best way to correct under-pronation’.
1.4 Objective
In our project, there must be a reason why it was conducted. Objective defined how successful the project has been. It is very useful to analyzing different types of foot pronation and its causes as we discussed above. So that we can identify the reason of foot ache and It gives the suitable way to treatment the foot ache.
1.5 Scope
We have outlined several scopes for the project. We can also make live application to analyze the patient foot by modifying some hardware like wireless data transmitting. We can use wireless media to transmit collected data by our various sensors instead of storing in SD card.Even our project will might be used in a game that uses the shoe as a controller.
‘
CHAPTER 2 IMPLEMENTATION OF PROJECT
2.1 Block Diagram
Block diagram is shown in figure given below. In this block diagram signal coming from all different types of sensors and goes to main program controller where it is manipulated to make a force map, acceleration rate and angular status of sensed foot and then send it all to SD card module where it is stored in removable memory storage for later interpretation by podiatrist.
FIG 7 Simplified block diagram
In our project block diagram we observe the different main process section which are mention below.
1) High level design
2) Software design
3) Hardware design
We will study about all different kind of design in next topics.
2.2 High Level Design
Our project consists of three main functions are
1. Data Measurement
2. Data Processing
3. Data Storage/Output
2.2.1 Data Measurement
Our data measurement function primarily replicates the abilities of an inertial measurement unit in a more specified manner. We decide to save on costs by sampling accelerometers and gyroscopes separately and implementing signal processing in the microcontroller. Since the ATMega644 has eight channels of analog-to-digital converters, we were able to include force-sensitive-resistors (FSRs) to our project. These resistors greatly decrease in resistance when a force is applied to the surface. By placing the sensors in strategic locations, we are able to figure out relative force distributions across the foot. Initially we sampled a digital output gyroscope from Analog Device.
2.2.2 Data Processing
Data processing conducts multiple functions to sense user steps detect the pronation of a user log their angular movement of the foot as it moves through the stride as well as output curves of the user. By using the network of sensors embedded in the shoe a basic model of how the user moves about can be generated.
2.2.3 Data StorageOutput
We decided that an SD card interface would be the best way to store large amounts of data and easily transport it from the shoe to a desktop computer. Once on the computer, the values can be parsed by MATLAB or some other custom program and the dataset can be easily plotted to reveal patterns in the user’s stride.
We also considered using an LCD screen to view the analog outputs of the project.
If we can achieve wireless function, we may explore the possibility of sending data wirelessly to a receiver point and then displaying it via LCD maybe like a watch.
2.3 Software Design
Our software is divided into three main modules like our high level design.
‘ Maintains program
‘ Control flow
‘ Data collection
o Data Monitoring
o Step Detection Processing
o Pronation Detection
o Writing to SD card
2.3.1 Maintains Program and Control Flow
Our sensor array utilizes three FSRs, two accelerometers and one dual-axis gyroscope. All our sensors utilize analog outputs therefore we utilize seven out of eight ADCs on the ATMega644. To switch between the different channels of the ADC we assign the 3-bit binary value corresponding to that channel to MUX2:0 bits in the ADMUX. It is important to maintain logic high in the REFS0 bit of ADMUX throughout the changing of ADMUX.Collected data should be store for analysis of person’s foot pronation characteristic. So that for we decide to use SD(secure digital) memory card for storing purpose and main program control the data storing action on SD card. SD card module configure with controller and main program control readwrite operation over SD card.
2.3.2 Data Collection
Main program controller collects various data from three different kind of sensor like:
2.3.2.1 Data Monitoring
A debug mode of our device allows the microcontroller to read ADC values from all its devices and store in memory device and also print them out in a pretty format for analysis from stored data. In a medical application, the shoe can then constantly stream data through USART as strings for post processing on another machine.
2.3.2.2 Step Detection Processing
Both the FSRs and the accelerometers output consistent enough data that both the falling and rising acceleration and the impact of the foot pressing into the ground and releasing for the next step could be used to detect a step. In our design, we selected to use the accelerometers to implement a three-state STATE MACHINE to detect and de-bounce a step.
2.3.2.3 Pronation Detection
Pronation detection is also done via a state machine, but in this case, we selected to use the force sensors. Pronation detection triggers when the heel FSR force surpasses a set threshold to signal the heel taking most of the subject’s weight as they roll toward the front of their foot. The STATE MACHINE then waits a short period for the front sensors to surpass their respective thresholds during a certain timeout window. If a forefoot force is detected, the exact force sensor that fired is located and depending on its physical location, pronation or supination can be determined.
We use our gyroscope to detect the exact degree of rolling that a foot undergoes when making a step, but conversions and integration of the ADC values from the gyroscope resulted in degree values that drifted linearly. This drift made most of our programming useless, so in the end, the more simplistic FSRs were used.
2.3.2.4 Writing to SD Card
We chose to use SD cards for our data storage because the interface is accessible via SPI, which is easily implemented with the ATMega644. Other reason for choosing SD card memory device due to their small size, less weight with large storing capacity most importance is that we can mount or un-mount at any time without disturbing rest of the implemented system. SD card is separate device can attached or detached into interfacing module to communicate with desktop.
2.4 What is State Machine?
The short definition of a state machine is a collection of steps (states) selected for execution based on the value in a state variable. Further, manipulation of the value in the state variable allows the state machine to emulate all the conditional statements.
Control systems that manage electrical or mechanical systems must often be able to generate or respond to sequential events in the system. This ability to use time as part of the driver equation is in fact one of the important abilities of a microcontroller that makes it such a good control for electrical and mechanical systems. However, implementing multiple sequences can become long and involved if a linear coding style is used.
State machine simplifies the task of generating a sequence by breaking the sequence into a series of steps and then executing them sequentially. While this sounds like an arbitrary definition of a linear piece of code the difference is that the individual sections or steps in the sequence are encoded within a SWITCH/CASE statement. Figure shows the logic implementation of sequential STATE MACHINE.
FIG 8 Sequential state machine
This breaks the sequence into logical units that can be easily recognized in the software listing and more importantly it allows other functions to be performed between the individual steps. It does this by only executing one step each time it is called. Repeatedly calling the state machine results in the execution of each step in the sequence.
To retain the state machine’s place in the sequence, a storage variable is defined that determines which step in the sequence is to be executed next. This variable is referred to as the state variable and it is used in the SWITCH/CASE statement to determine which step or state in the state machine is to be executed when the state machine is called.
For this system to work, the state variable must be incremented at the completion of each state. However, it is also true that the sequence of states may need to change due to changes in the condition of the system. Given that the state variable determines which state is executed, it follows that to change the sequence of states and one must simply load the state variable with a new value corresponding with the new direction the sequence must go.
2.4.1 Advantages of State Machine
‘ The first advantage is using state machines inherently promotes good design techniques.
‘ Prevent developing bugs in the code.
‘ It allows the easy generation of a sequence of events.
‘ Its ability to recognize a sequence of events. It does this by utilizing the conditional change of the state variable.
2.4.2 Drawback of State Machine
The state variable does not normally change its value, unless a specific event is detected.
2.5 Hardware Design
Our hardware, we integrates three different kinds of sensors to measurements and track a user’s
‘ Movement speed
‘ Regularity of gait
‘ Force on impact
‘ Pronation of foot
As well as other information that may be useful to a podiatrist. We believe there is a need for a cheap metering tool that can be used to log long-term data for later interpretation by a podiatrist. For our project, we used the following hardware functional blocks:
‘ ATMega644 Target Board
‘ MMA7261L Accelerometer
‘ Force Sensitive Resistors
‘ LPR503AL Dual-Axis gyroscope
‘ SD Card Module
‘ 9V to 5V Voltage Converter
We studies about each hardware sections briefly and know about its function, working principle, its physical construction, application and etc in next chapters.
‘
CHAPTER 3 ATMEL ATMEGA644 TARGET BOARD
In hardware section main controller target board contain following different block are:
‘ ATMega644-20PU Atmel microcontroller
‘ Power supply circuit
‘ Oscillator circuit
‘ Reset circuit
3.1 ATMEGA644 controller
‘ATMEGA644’ is as our main program controller which stored control procedures of the all sensors connected to that controller to gather the information about various parameter like movement speed, angle, force etc. It will get the instant values from the all sensor at a particular time interval and proceed on that and also stored in to memory device attached with controller.
In our project we are going to implement ‘ATMEGA644’developed by ‘ATMEL corporation’ controller as main program controller to accomplish the entire sensors and output device like memory card.
3.1.1 About ‘ATMEL Corporation’
Atmel Corporation is a worldwide leader in the design and manufacture of microcontrollers, capacitive touch solutions, advanced logic, mixed signal, nonvolatile memory and radio frequency components. Leveraging one of the industry’s broadest intellectual property technology portfolios, Atmel provides the electronics industry with complete system solutions focused on industrial, consumer, security, communications, computing and automotive markets.
FIG 9 Atmel Corporation
Today microcontrollers are just about everywhere, powering an expansive array of digital devices. Many are calling this the era of The Internet of Things, a highly intelligent, connected world where Internet-enabled devices will outnumber people. Atmel is pleased to be at the heart of this movement developing innovative technologies that fuel machine-to-machine communication and the industrial Internet.
3.2 Atmega644 Micro-Controller Features
The ATmega644 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega644 achieves throughputs approaching 1 MIPS per MHz allowing the system designed to optimize power consumption versus processing speed.
‘ High-performance, Low-power AtmelAVR8-bit Microcontroller
‘ Advanced RISC Architecture
‘ 131 Powerful Instructions ‘ Most Single-clock Cycle Execution
‘ 32 ?? 8 General Purpose Working Registers
‘ Fully Static Operation
‘ Up to 20 MIPS Throughput at 20MHz
‘ High Endurance Non-volatile Memory segments
‘ 64 Kbytes of In-System Self-programmable Flash program memory
‘ 2 Kbytes EEPROM
‘ 4 Kbytes Internal SRAM
‘ Write/Erase cycles: 10,000 Flash/100,000 EEPROM
‘ Data retention: 20 years at 85??C/100 years at 25??C
‘ Optional Boot Code Section with Independent Lock Bits
‘ In-System Programming by On-chip Boot Program
‘ True Read-While-Write Operation
‘ JTAG (IEEE std. 1149.1 Compliant) Interface
‘ Boundary-scan Capabilities According to the JTAG Standard
‘ Extensive On-chip Debug Support
‘ Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface
‘ Peripheral Features
‘ Two 8-bit Timer/Counters with Separate Pre-scalars and Compare Modes
‘ One 16-bit Timer/Counter with Separate Pre-scalar, Compare Mode, and Capture
‘ Mode
‘ Real Time Counter with Separate Oscillator
‘ Six PWM Channels
‘ 8-channel, 10-bit ADC
‘ Differential mode with selectable gain at 1x, 10x or 200x
‘ Byte-oriented Two-wire Serial Interface
‘ One Programmable Serial USART
‘ Master/Slave SPI Serial Interface
‘ Programmable Watchdog Timer with Separate On-chip Oscillator
‘ On-chip Analog Comparator
‘ Interrupt and Wake-up on Pin Change
‘ Special Microcontroller Features
‘ Power-on Reset and Programmable Brown-out Detection
‘ Internal Calibrated RC Oscillator
‘ External and Internal Interrupt Sources
‘ Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standbyand Extended Standby
‘ I/O and Packages
‘ 32 Programmable I/O Lines
‘ 40-pin PDIP, 44-lead TQFP and 44-pad QFN/MLF
3.3 Packaging
ATMEGA644 controller ic available in different types of two packages
1) DIP package in 40 pins(dual in line package)
2) QFP package in 44 pins(quad flat package)
3.3.1 Pin diagram of DIP-40pin ATMEGA644 controller
FIG 10 pin diagram of ATMEGA644
FIG 11 Package view of atmega644
3.3.2 QFP-44 pin ATMEGA644 controller
FIG 12 Pin diagram of quadpack atmega644
FIG 13 Quad package view of atmega644
3.4 Pin Descriptions
Pin no 10: VCC
Digital supply voltage ranging from 1.8 to 5.5V.
Pin no 11 & 32: GND
Ground the power supply.
Pin no 33 to 40: Port A (PA7:PA0)
Port A serves as analog inputs to the Analog-to-digital Converter. Port A also serves as an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port A output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port A pins that are externally pulled low will source current if the pull-up resistors are activated. The Port A pins are tri-stated when a reset condition becomes active even if the clock is not running.
Pin no 1 to 8: Port B (PB7:PB0)
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active even if the clock is not running.
Pin no 22 to 29: Port C (PC7:PC0)
Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port C output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active even if the clock is not running.
Pin no 14 to 21: Port D (PD7:PD0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active even if the clock is not running.
Pin no 9: RESET
Reset input. A low level on this pin for longer than the minimum pulse length will generate a reset even if the clock is not running. The minimum pulse length is given in ‘System and Reset Characteristics’ on page 320. Shorter pulses are not guaranteed to generate a reset.
Pin no 13: XTAL1
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
Pin no 12: XTAL2
Output from the inverting Oscillator amplifier.
Pin no 30: AVCC
AVCC is the supply voltage pin for Port F and the Analog-to-digital Converter. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter.
Pin no 32: AREF
This is the analog reference pin for the Analog-to-digital Converter.
3.5 Power supply circuit
In this block, we use 9v battery to convert DC voltage to 5V DC. Power Supply is the device that transfers electric power from a source to a load using electronic circuits. Power supplies are used in many industrial and aerospace applications and also in consumer products. Some of the requirements of power supplies are small size, lightweight, low cost, and high power conversion efficiency. In addition to these, some power supplies require the following: electrical isolation between the source and load, low harmonic distortion for the input and output waveforms, and high power factor (PF) if the source is ac voltage. Some special power supplies require controlled direction of power flow. Typical application of power supplies is to convert input power to a regulated voltage(s) required for electronic equipment. Depending on the mode of operation of power semiconductors power supply can be linear or switching.
FIG 14 Power circuit
In our power supply circuitry we used LM7805 regulated power integrated circuit(IC) simply inputted from 9V dc battery and IC regulated input voltage to fix 5V DC supply to microcontroller and others sensors.
3.5.1 IC 7805 (Voltage Regulator)
Voltage regulators ICs are available with fixed (typically 5, 12 and 15V) or variable output voltages. They are also rated by the maximum current they can pass. Negative voltage regulators are available, mainly for use in dual supplies. Most regulators include some automatic protection from excessive current (‘overload protection’) and overheating (‘thermal protection’).
FIG 15 Power ic 7805
3.5.1.1 General Description of IC 7805:
The IC7805 is a three-terminal positive voltage regulator employ built-in current limiting, thermal shutdown, and safe-operating area protection which makes them virtually immune to damage from output overloads. With adequate heat sinking, they can deliver in excess of 0.5A output current. Typical applications would include local (on-card) regulators which can eliminate the noise and degraded performance associated with single-point regulation.
FIG 16 Schematic of power ic 7805
3.5.1.2 Features of IC 7805:
‘ Output current in excess of 0.5A.
‘ Internal thermal overload protection.
‘ Internal short circuit current-limiting.
‘ Output voltages of 5V, 12V, and 15V.
3.6 Crystal oscillator circuit
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz. More than two billion crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes.
Atmega644-20PU micro controller operated at 20MHz clock frequency which is generated by crystal. We use 20MHz quartz crystal. Figure shows given below the crystal circuit interface to micro controller pin no 18 and 19.
FIG 17 Crystal circuit
3.7 Reset circuit
3.7.1 Description
The AVR’s RESET pin is an active-low input that forces a reset of the processor and its integrated peripherals. The line can be driven by an external power-on reset generator, a voltage supervisor (which asserts RESET when the power supply voltage drops below a predefined threshold), or another component in a larger system. For example, if the AVR is managing a few sensors and servos as part of a large integrated system, another controller might observe some condition that justifies resetting the AVR. it could do so by asserting the AVR’s RESET line.
AVRs also include a watchdog timer, which can reset the processor when it times out. The watchdog timer must be reset periodically to prevent it from timing out. Failure to reset the watchdog timer is usually an indication that the program code has failed (locked up, entered an infinite loop, or otherwise gone astray), and the processor should be reset. On some AVRs the watchdog can be programmed to issue an interrupt instead of resetting the processor. This functionality can be used to wake up the AVR from a sleep mode.
FIG 18 Basic reset circuit
The RESET pin is used for in-system serial programming, as a GPIO, low pin count debugging, depending on the chip and the programming of the fuse bits. If the reset functionality of that pin is disabled, it cannot be recovered by in-system serial programming, and another method such as high-voltage programming must be used.
3.7.2 Reset circuit with ATMEGA644
Figure shows the basic reset circuit for ATMEGA644.
FIG 19 Reset circuit interface with ATMEGA644
3.8 Minimum hardware configuration of ATMEGA644
For any ATMEGA644 controller application it is essential to required minimum hardware like power supply, appropriate crystal oscillator circuit and reset circuit. Figure shows the essential hardware interfacing In which we applied 5v dc supply to our controller driven by power circuit or fixed voltage regulator connected to pin no 10, and both reset circuit with power on and manually achieved by one push button switch connected to pin no 9 of our micro controller, and one other most importance circuit is oscillator circuit made by using quard crystal to the controller pin no 12and pin no 13.
FIG 20 Essential hardware interface of ATMEGA644
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CHAPTER 4 ACCELEROMETER
An accelerometer is a device that measures proper acceleration. The proper acceleration measured by an accelerometer is not necessarily the coordinate acceleration.in our project we used free-scale accelerometer MMA7361L.before we discuss more about accelerometer MMA7361L, we study ‘what is accelerometer’
4.1 Working Principle:
An accelerometer is the acceleration it experiences relative to free-fall and is the acceleration felt by people and objects. Put another way, at any point in space time the equivalence principle guarantees the existence of a local inertial frame, and an accelerometer measures the acceleration relative to that frame. Such accelerations are popularly measured in terms of g-force.
FIG 21 Working principle of accelerometer
An accelerometer at rest relative to the Earth’s surface will indicate approximately 1 g upwards, because any point on the Earth’s surface is accelerating upwards relative to the local inertial frame. To obtain the acceleration due to motion with respect to the Earth, this "gravity offset" must be subtracted and corrections made for effects caused by the Earth’s rotation relative to the inertial frame.
The reason for the appearance of a gravitational offset is Einstein’s equivalence principle which states that ‘the effects of gravity on an object are indistinguishable from acceleration.’ When held fixed in a gravitational field by for example applying a ground reaction force or an equivalent upward thrust, the reference frame for an accelerometer (its own casing) accelerates upwards with respect to a free-falling reference frame. The effects of this acceleration are indistinguishable from any other acceleration experienced by the instrument, so that an accelerometer cannot detect the difference between sitting in a rocket on the launch pad, and being in the same rocket in deep space while it uses its engines to accelerate at 1 g.
4.1.1 What is G-force?
G-force is pronounced as ‘gravitationalforce’ is a measurement of acceleration felt as weight. It is not a force, but a force per unit mass and can be measured with an accelerometer. Since such a force is perceived as a weight, any g-force can be described as a "weight per unit mass".
FIG 22 Gravitation force
The g-force acceleration acts as a multiplier of weight-like forces for every unit of an object’s mass, and is the cause of an object’s acceleration in relation to free-fall
4.2 Structure of Accelerometer
Conceptually, an accelerometer behaves as a damped mass on a spring. When the accelerometer experiences acceleration, the mass is displaced to the point that the spring is able to accelerate the mass at the same rate as the casing. The displacement is then measured to give the acceleration.
FIG 23 a) Spring mass system without acceleration
b) Spring mass system with acceleration
In commercial devices, piezoelectric, piezo-resistive and capacitive components are commonly or single used to convert the mechanical motion into an electrical signal. Piezoelectric accelerometers rely on piezo-ceramics crystals. They are unmatched in terms of their upper frequency range, low packaged weight and high temperature range. Piezo-resistive accelerometers are preferred in high shock applications. Capacitive accelerometers typically use a silicon micro-machined sensing element. Their performance is superior in the low frequency range and they can be operated in servo mode to achieve high stability and linearity.
Modern accelerometers are often small micro electro-mechanical systems (MEMS), and are indeed the simplest MEMS devices possible, consisting of little more than a cantilever beam with a proof mass. Damping results from the residual gas sealed in the device. As long as the Q-factor is not too low, damping does not result in a lower sensitivity.
4.3 free-scale MMA7361L accelerometer
The MMA7361L is a low power, low profile capacitive micro machined Accelerometer featuring signal conditioning, a 1-pole low pass filter Temperature compensation, self-test, 0g-Detect which detects linear freefall And g-Select which allows for the selection between 2 sensitivities. Zero-g Offset and sensitivity are factory set and require no external devices. The MMA7361L includes a Sleep Mode that makes it ideal for handheld battery Powered electronics.
4.3.1 Features
‘ 3mm x 5mm x 1.0mm LGA-14 Package
‘ Low Current Consumption: 400 ??A
‘ Sleep Mode: 3 ??A
‘ Low Voltage Operation: 2.2 V ‘ 3.6 V
‘ High Sensitivity (800 mV/g @ 1.5g)
‘ Selectable Sensitivity (??1.5g, ??6g)
‘ Fast Turn on Time (0.5 MS Enable Response Time)
‘ Self-Test for Freefall Detect Diagnosis
‘ 0g-Detect for Freefall Protection
‘ Signal Conditioning with Low Pass Filter
‘ Robust Design, High Shocks Survivability
‘ RoHS Compliant
‘ Environmentally Preferred Product
‘ Low Cost
4.3.2 Function block diagram of MMA7361L
FIG 24 Function block diameter of MMA7361L ACCELEROMETER
4.3.3 Pin description
FIG 25 Pin diagram of MMA7361L
TABLE 1 Pin description of MMA7361L
4.3.4 Application
Accelerometers MMA7361L used in many different kind of field like:
‘ 3D Gaming: Tilt and Motion Sensing, Event Recorder
‘ HDD MP3 Player: Freefall Detection
‘ Laptop PC: Freefall Detection, Anti-Theft
‘ Cell Phone: Image Stability, Text Scroll, Motion Dialing, E-Compass
‘ Pedometer: Motion Sensing
‘ PDA: Text Scroll
‘ Navigation and Dead Reckoning: E-Compass Tilt Compensation
‘ Robotics: Motion Sensing
4.3.5 Accelerometer module
Accelerometer sensor can measure static (earth gravity) or dynamic acceleration in all three axis. Application of the sensor is in various fields and many applications can be developed using this sensor.
FIG 26 Accelerometer MMA7361L module
Accelerometer sensor measures level of acceleration where it is mounted this enable us to measure acceleration/deceleration of object like car or robot, or tilt of a platform with respected to earth axis, or vibration produced by machines. Sensor provides 0G output which detect linear free fall. Sensitivity can be adjusted in two ranges.
Acceleration is a vector force which has direction and measured in meters per second. Earth produces gravitational acceleration on all objects on earth. By monitoring the three axis acceleration one can measure the level of tilt of any platform.
4.3.6 Specifications
Board Supply Voltage +5 V DC Board has regulator IC to convert +5V to 3.3V DC since sensor IC operates on 3.3V only
Operation Current 1 ma
Operating Temperature -40 to +85 deg Celsius
Zero G output voltage (X,Y,Z) 1.65V Idle output is VDD/2
So 3.3V/2=1.65V
Output on Sensitivity Range 1.5g
Output on Sensitivity Range 6g
800mV per g
200mV per g
The device can measure both + and ‘ acceleration. With no input acceleration the output is at midsupply.
For positive acceleration the output will increase above 1.65V
For negative acceleration, the output will decrease below 1.65V
0g Detect +3.3V output on detect
+0V output on idle mode
Active High 3V signal on free fall
The sensor offers a 0g-Detect feature that provides a logic high signal when all three axes are at 0g. This feature enables the application of Linear Freefall protection if the signal is connected to an interrupt pin or a poled I/O pin on a microcontroller.
TABLE 2 Specification of accelerometer MMA7361L
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CHAPTER 5Gyroscope
5.1 Description
To measure the angular movement rate of the shoe, we decided to use a gyroscope simplify our data processing. The analog output of the gyroscope was much easier to use. The breakout board already contained all the necessary filtering capacitors and header pins. We provided 5v and connected the 1X output to our ADC and instantly get result. We use full break out board instead of gyroscope IC because there is problem to soldering SMD IC.
5.2 Structure of gyroscope
A gyroscope is a device for measuring or maintaining orientation based on the principles of angular momentum. Mechanically, a gyroscope is a spinning wheel or disc in which the axle is free to assume any orientation. Although this orientation does not remain fixed, it changes in response to an External torquemuch less and in a different direction than it would without the large angular momentum associated with the disc’s high rate of spin and moment of inertia. The device’s orientation remains nearly fixed, regardless of the mounting platform’s motion, because mounting the device in a gimbal minimizes external torque.
FIG 27 Working principle of gyroscope
In our design we used gyro + accelerometer sensor based on MPU6050 discussed in next topic.
5.3 Gyro + accelerometer sensor, 3 axis based on MPU6050
It contains 16-bits ADC for each channel. Outputs x, y, and z channels. The MPU-6050 is a serious little piece of motion processing tech! By combining a MEMS 3-axis gyroscope and a 3-axis accelerometer on the same silicon die together with an onboard Digital Motion Processor capable of processing complex 9-axis Motion Fusion algorithms, the MPU-6050 does away with the cross-axis alignment problems that can creep up on discrete parts.
FIG 28 Gyroscope module
5.3.1 Features
The triple-axis MEMS gyroscope in the MPU-60X0 includes a wide range of features:
‘ Digital-output X-, Y-, and Z-Axis angular rate sensors (gyroscopes) with a user-programmable full-scale range of ??250, ??500, ??1000, and ??2000??/sec
‘ External sync signal connected to the FSYNC pin supports image, video and GPS synchronization
‘ Integrated 16-bit ADCs enable simultaneous sampling of gyros
‘ Enhanced bias and sensitivity temperature stability reduces the need for user calibration
‘ Improved low-frequency noise performance
‘ Digitally-programmable low-pass filter
‘ Gyroscope operating current: 3.6mA
‘ Standby current: 5??A
‘ Factory calibrated sensitivity scale factor’
CHAPTER 6 Force Sensitive Resistor
In this chapter we will study about force sensitive resistor which is used in project to sense the force impact on foot from ground. During walking or running condition various amount of force impact at various point in our foot-print.
6.1 What is force sensitive resistor?
A force-sensing resistor is a material whose resistance changes when a force or pressure is applied. They are also known as "force-sensitive resistor" and are sometimes referred to by the initials "FSR".Force Sensing Resistors (FSR) are a polymer thick film (PTF) device which exhibits a decrease in resistance with an increase in the force applied to the active surface. Its force sensitivity is optimized for use in human touch control of electronic devices. FSRs are not a load cell or strain gauge, though they have similar properties. FSRs are not suitable for precision measurements.
6.2 Features and Benefits
‘ Actuation Force as low as 0.1N and sensitivity range to 10N.
‘ Easily customizable to a wide range of sizes
‘ Highly Repeatable Force Reading As low as 2% of initial reading with repeatable actuation system
‘ Cost effective
‘ Ultra-thin 0.45mm
‘ Robust up to 10M actuations
‘ Simple and easy to integrate
6.3 Typical Schematic
FIG 29 Schematic of FSR
6.4 Structure of FSR
Force-sensing resistors consist of a conductive polymer, which changes resistance in a predictable manner following application of force to its surface. They are normally supplied as a polymer sheet or ink that can be applied by screen printing. The sensing film consists of both electrically conducting and non-conducting particles suspended in matrix. The particles are sub-micrometer sizes, and are formulated to reduce the temperature dependence, improve mechanical properties and increase surface durability.
FIG 30 Structure of FSR
Active Area: 38.1mm x 38.1mm’
Nominal thickness: 0.54 mm
Applying a force to the surface of a sensing film causes particles to touch the conducting electrodes, changing the resistance of the film. As with all resistive based sensors, force-sensing resistors require a relatively simple interface and can operate satisfactorily in moderately hostile environments. Compared to other force sensors, the advantages of FSRs are their size (thickness typically less than 0.5 mm), low cost and good shock resistance. However, FSRs will be damaged if pressure is applied for a longer time period (hours). A disadvantage is their low precision: measurement results may differ 10% and more.
FIG 31 FSR datasheet characteristic
6.5 Interfacing with ATMEGA644
We used three FSRs underneath the insole of our shoe to supplement our pronation/supination detection by analyzing the force on both the inside and outside edge of the shoe. The FSRs vary in resistance greatly as force is applied to them. Although the decrease is not linear, we can get a rough idea of relative force. We used the FSR as the resistor tied to Vcc in a voltage divider. Through trial and error, we determined that a 1K resistor tied to ground provided the best resolution throughout the range of forces applied during normal human gait for the sensors at the ball and outer edge. Since less force is on the heel, we used a 330 ohm resistor for that sensor only. As more force is placed on the FSRs, the resistance drops and a greater voltage is dropped across the series resistor leading to a higher ADC value.
FIG 32 FSR schematic
CHAPTER 7 SD Card Module
We will use SD card module to stored capturing data into memory device like SDcard.Using an integrated SD card, each patient would be able to provide weeks’ worth of data to the podiatrist, capturing the many activities we encounter throughout the day.
7.1 Description
SDcard abbreviated of Secure Digital (SD) is flash memory technologies are quickly becoming the preferred solution for portable, consumer and industrial electronic devices around the world for storing a large amount of information in a small, durable, portable form factor. The SD Card user module’s ability to quickly and easily write to &read from and seamlessly integrate an SD card module into an embedded design.
FIG 33 SD card module
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7.2 Secure Digital (SD Card)
Secure Digital (SD) is a non-volatile memory card format for use in portable devices such as mobile phones, cameras, GPS, and tablet computers.
The Secure Digital standard was introduced in 1999 as an evolutionary improvement over Multimedia Cards (MMC). The Secure Digital standard is maintained by the SD Card Association (SDA). SD technologies have been implemented in more than 400 brands across dozens of product categories and more than 8,000 models.
The Secure Digital format includes four card families available in three different form factors. The four families are
‘ SD Standard-Capacity (SDSC)
‘ High-Capacity (SDHC)
‘ Extended-Capacity (SDXC)
‘ SD input-output(SDIO)
The three form factors are
‘ Original size(32.0??24.0??2.1 mm )
‘ Mini size( 21.5??20.0??1.4 mm )
‘ Micro size(15.0??11.0??1.0 mm )
No table of figures entries found.
FIG 34various sizes of SD card
Electrically passive adapters allow the use of a smaller card in a host device built to hold a larger card.
7.2.1 Features of SD Card
‘ Card Security
Cards can protect their contents from erasure or modification, prevent access by non-authorized users, and protect copyrighted content using digital rights management (DRM).
‘ Commands to Disable Writes
The host device can command the SD card to become read-only (to reject subsequent commands to write information to it). There are both reversible and irreversible host commands that achieve this.
‘ Write-Protect Notch
The user can designate most full-size SD cards as read-only by use of a sliding tab that covers a notch in the card. The presence of a notch, and the presence and position of a tab, have no effect on the SD card’s operation. A host device that supports write protection should refuse to write to an SD card that is designated read-only in this way. Some host devices do not support write protection, which is an optional feature of the SD specification. Drivers and devices that do obey a read-only indication may give the user a way to override it.
‘ Card Password
A host device can lock an SD card using a password of up to 16 bytes, typically supplied by the user. A locked card interacts normally with the host device except that it rejects commands to read and write data. A locked card can be unlocked only by providing the same password. The host device can, after supplying the old password, specify a new password or disable locking. Without the password, the host device can command the card to erase all the data on the card for future re-use, but there is no way to gain access to the existing data.
‘ DRM Copy-Protection
All cards incorporate DRM copy-protection. Roughly 10% of the storage capacity of an SD card is a "Protected Area" not available to the user, but is used by the on-card processor to verify the identity of an application program that it then allows to read protected content. The card prohibits other accesses, such as users trying to make copies of protected files.
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7.3 SD Card Module Interface
The Micro SD Card breakout Interface module is designed for dual I/O voltages. The interface module can be used with 3.3V or 5V logic level. The SD Card interface board can be used with any microcontroller. Figure shows the interfacing MMC-SD card module in protues circuit simulater.
FIG 35 Interfacing module with controller
7.4 Serial Peripheral Interface (SPI)
SPI, the Serial Peripheral Interface Bus, is a master-slave synchronous serial protocol. This means that there is a clock line which determines where the pulses are to be sampled, and that one of the parties is always in charge of initiating communication. It uses at least four lines, which are called:
MISO(Master in Slave Out)
MOSI (Master Out Slave In)
SCK(Serial Clock)
CS(Chip select)
Conceptually, SPI is a bidirectional shift register; as bits are shifted out on either MISO or MOSI, bits are shifted in on the other line. The master always controls the clock. An SPI slave has a Slave Select (SS) signal, which signals to the slave that it should respond to messages from the master. SS is almost always active-low. If there is only one master and one slave, the slave’s SS line could be tied low, and the master would not need to drive it. If there are two or more slaves, then the master must use a separate slave select signal to each slave. The downside of this approach is that the master can only address as many slaves as it has extra outputs (without the use of a separate decoder).
Hardware Implementation
The larger AVR microcontrollers have built-in SPI transceivers. The serial clock is derived from the processor clock, with several divisors available. The data length is always 8 bits. The clock polarity and phase may be configured, leading to four possible combinations of when the data is clocked in and out of the chip. This interface is very popular, and is widely available on a variety of other processors and peripherals. The pins used for the SPI bus are also used as a way of programming the chip via ISP.
Universal Serial Interface
Some AVRs, particularly in the tiny family, provide a Universal Serial Interface (USI) instead of an SPI. The USI is capable of operating as an SPI, but also as an I2C controller, and with a little extra effort, a USART. The bit length of the transfer is configurable, as is the clock driver. The clock can be driven by software, by the timer 0 overflow, or by an external source.
Software Implementation
SPI can be implemented using bit-banging of the I/O lines. An efficient implementation of a slave can be done by connecting SCLK to an external interrupt source.The datasheet for a particular AVR provides a block diagram of the SPI or USI controller on that chip.
CHAPTER 8 HARDWARE CIRCUIT
8.1 Circuit diagram
FIG 36 Complete circuit diagram
8.2 Simulating circuit in PROTEUS
FIG 37 Simulating snapshot
8.3 Hardware circuit view
FIG 38 hardware circuit view
8.4 Hardware circuit PCB bottom view
FIG 39 Hardware circuit PCB bottom view
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CONCLUSION
This inexpensive foot monitoring device can be used in various ways by the public. Podiatrists can use this devicefor simple examinations to determine if a patient is standing or walking in an unusual way. Casual runners can findhow they are pronated and by how much to determine an ideal running shoe for them. If they’d rather not decidefor themselves, they can also bring in their SD card of running data in to a professional to be analysed. Moreprofessional runners and/or hobbyists can use the shoe to monitor their running form and patterns. They canmonitor their force curves to see if their legs are smoothly transferring weight from foot to foot.
REFERENCE
Papers:
1. KseniaKozak, ZviLadin, John M. Giurini, BIOMECHANICAL ASSESSMENT OF ORTHOTICS PRESCRIBED FOR EXCESSIVE PRONATION
2. Xiaoping Yun, Fellow, IEEE, James Calusdian, Eric R. Bachmann, Member, IEEE, and Robert B. McGhee, Life Fellow, Estimation of Human Foot Motion During Normal Walking Using Inertial and Magnetic Sensor Measurements
3. KeijiIramina, Member, IEEE, Yuuichiro Kamei, Yoshinori Katayama, Evaluation System for Minor Nervous Dysfunction by Pronation and Supination of Forearm using Wireless Acceleration and Angular Velocity Sensors
4. Pedobarographic Gait Analysis on Male Subjects J. Ray Department of Mechanical Engineering University of Memphis Memphis, Tennessee 38 152 D. Snyder Schering Plough Corporation 3030 Jackson Avenue Memphis, Tennessee 3 8 15 1
5. The comparison with the function of children’s pronation and supination using acceleration and angular velocity sensors, Miki Kaneko Kyushu University Graduate School of Systems Life Sciences Fukuoka, Japan
6. Engineering in Medicine and Biology Society, 1990., Proceedings of the Twelfth Annual International, Conference of the IEEE, Date of Conference: 1-4 Nov 1990
7. Instrumentation and Measurement, IEEE Transactions on (Volume:61 , Issue: 7 ), Date of Publication: July 2012
8. Engineering in Medicine and Biology Society,EMBC, 2011 Annual International Conference of the IEEE, Date of Conference: Aug. 30 2011-Sept. 3 2011
9. Biomedical Engineering International Conference (BMEiCON), 2012, Date of Conference: 5-7 Dec. 2012
10. Prognostics and System Health Management Conference (PHM-Shenzhen), 2011, Date of Conference: 24-25 May 2011
Books
11.Muhammad Ali Mazidi – AVR Microcontroller and Embedded Systems: Using Assembly and C , Pearson Education.
12.Richard H. Barnett, Sarah A. Cox, Larry D. O’Cull – Embedded C Programming and the Atmel AVR , Thomson Delmar Learning, 2002.
Web Link
11. http://people.ece.cornell.edu/land/courses/ece4760/FinalProjects/s2011/ylw3/webpage/
12. http://science.howstuffworks.com/gyroscope1.htm
13. http://learn.adafruit.com/force-sensitive-resistor-fsr
14. http://en.wikipedia.org/w/index.php?title=Laser_accelerometer&oldid=475536736
15. http://en.wikipedia.org/w/index.php?title=Piezoelectric_accelerometer&oldid=532546632