Voice Controlled Wheelchair

Voice Controlled Wheelchair

CHAPTER 1

INTRODUCTION This topic aims at controlling a wheelchair for handicaps by means of human voice. The speech recognition system is a useful way of implementation and is easy to use programmable speech recognition circuit. Programmable, in the sense that user can train the words (or vocal utterances) utterances) he needs the circuit to recognize. recognize. This board allows the user to experiment with many facets of speech recognition technology. It has 8-bit data out, which can be interfaced with any micro controller for further development. Some of interfacing applications which can be made are controlling home appliances, wheelchair wheelchair movements, movements, Speech Assisted Assisted technologie technologies, s, Speech Speech to text translation, translation, and many more. The wheelchair wheelchair is controlled by voice commands. commands. This can be moved in forward and reverse direction using geared motors of 60RPM. Also this wheelchair is a type of robot which can take sharp turnings towards left and right directions. It uses PIC16F72 MCU as its controller. It uses 6V battery. 1.1 BASIC IDEA :

In this topic, the controlling of a wheelchair by speech will be studied. Commands are spoken into a microphone, followed by an action by the wheelchair. Voice Controlled Wheelchair is a kind of a mobile robot whose motions can be controlled by the user by giving specific voice commands. The speech recognition software running on a PC is capable of identifying the 5 voice commands ‘Run’, ‘Stop’, ‘Left’, ’Right’ and ‘Back’ issued by a particular user. After processing the speech, the necessary motion instructions are given to the mobile platform via a RF link.

Department of Electronic & Communication Engineering K.B.N College of Engineering, Gulbarga

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Voice Controlled Wheelchair The speech recognition recognition software is speaker speaker dependant. dependant. The special feature of the application is the ability of the software to train itself for the voice commands(‘Run’, ‘Stop’, ‘Left’, ’Right’ and ‘Back’) for a particular user. The graphical user interface running along with the software provides a very convenient method for the users to train. It also provides many other facilities in operating the wheelchair.

In this topic we will be using visual basic (VB6.0) as our speech recognition application.

Figure 1.1: Block diagram of Voice Controlled Wheelchair


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CHAPTER 2

COMPONENT 2.1 MAIN COMPONENTS: 

PIC 16f72 Microcontroller



RF 434MHz Tx-Rx



Electro-magnetic Relays



Mike/ Microphone



Geared motors



Serial port- RS232

2.2 OTHER COMPONENTS: 

Diode



Resistors



IC 7805- Voltage regulator



Battery



Crystal oscillator



LED



PCB



IC base


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Voice Controlled Wheelchair 2.3 POWER SUPPLY: Power supply is the basic requirement of any electronics device.we have used a 6V battery to run the 60RPM geared motors. 9V batteries are used to run the relay circuit and RF 434MHz Tx-Rx. 12V power supply will be provided by the PC which would be converted into 5V by Voltage Regulator (7805).

2.3.1 VOLTAGE REGULATOR:

The Digilab board can use any power supply that creates a DC voltage between 6 and 12 volts. A 5V voltage regulator (7805) is used to ensure that no more than 5V is delivered to the Digilab board regardless of the voltage present at the J12 connector (provided that voltage is less than 12VDC). The regulator functions by using a diode to clamp the output voltage at 5VDC regardless of the input voltage - excess voltage is converted to heat and dissipated through the body of the regulator. If a DC supply of greater than 12V is used, excessive heat will be generated, and the board may be damaged. If a DC supply of less than 5V is used, insufficient voltage will be present at the regulators output.

Figure 2.3.1: Voltage Regulator


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Voice Controlled Wheelchair If a power supply provides a voltage higher than 7 or 8 volts, the regulator must dissipate significant heat. The "fin" on the regulator body (the side that protrudes upward beyond the main body of the part) helps to dissipate excess heat more efficiently. If the board requires higher currents (due to the use of peripheral devices or larger breadboard circuits), then the regulator may need to dissipate more heat. In this case, the regulator can be secured to the circuit board by fastening it with a screw and nut (see below). By securing the regulator tightly to the circuit board, excess heat can be passed to the board and then radiated away

Figure 2.3.2: Regulator Implemented on a PCB

We have used a L.E.D as an indicator that indicates the conversion of ac voltage into dc. When the transformation is done the L.E.D glows and it continues to do so till there is supply available for the circuit to work.

Figure 2.3.3.: Power Supply Circuit


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Voice Controlled Wheelchair 2.4 PIC 16F72 MICROCONTROLLER:

We use microcontroller PIC 16f72, which is at the upper end of the mid-range series of the microcontrollers developed by Microchip Inc. It is characterized by RISC architecture instead of the CISC architecture used, for example, by the Motorola 6809.

The PIC series of microcontrollers are RISC-based processors with an accumulator (also called the working register, W), which use the Harvard3 architecture; therefore the microcontroller has a program memory data bus and a data memory data bus. Separate buses mean that simultaneous access of program and data can be done, which gives a greater bandwidth over the traditional won Neumann architecture. Separating the program and data memory, allows instructions to be sized differently than the 8-bit wide data word. This separation means that the instruction words can be ideally sized for the specific CPU/application. This is necessary since RISC architectures require that instructions have the source and destination operands be encoded within the instruction.

High Performance RISC CPU:



Only 35 single word instructions to learn



All single cycle instructions except for program branches, which are two-cycle



Operating speed: DC - 20 MHz clock input DC - 200 ns instruction cycle



2K x 14 words of Program Memory, 128 x 8 bytes of Data Memory (RAM)



Pinout compatible to PIC16C72/72A and PIC16F872



Interrupt capability



Eight-level deep hardware stack



Direct, Indirect and Relative Addressing modes


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Voice Controlled Wheelchair Special Micro controller Features: 

1,000 erase/write cycle FLASH program memory typical



Power-on Reset (POR), Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)



Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation



Programmable code protection



Power saving SLEEP mode



Selectable oscillator options



In-Circuit Serial Programming™ (ICSP™) via 2 pins



Processor read access to program memory

Figure 2.4.1 : Pin diagram


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2.4.1 DESCRIPTION OF 16f72: The PIC16F72 belongs to the Mid-Range family of the PIC micro devices. The program memory contains 2K words, which translate to 2048 instructions, since each 14-bit program memory word is the same width as each device instruction. The data memory (RAM) contains 128 bytes.

There are 22 I/O pins that are user configurable on a pin-to-pin basis. Some pins are multiplexed with other device functions. These functions include: 

External interrupt



Change on PORTB interrupts



Timer0 clock input



Timer1 clock/oscillator



Capture/Compare/PWM



A/D converter



SPI/I2C


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Voice Controlled Wheelchair 2.4.2 BLOCK DIAGRAM OF PIC 16f72:

Figure 2.4.2 : Block diagram of 16f72


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Voice Controlled Wheelchair 2.4.3 MEMORY ORGANIZATION: There are two memory blocks in the PIC16F72 device. These are the program memory and the data memory. Each block has separate buses so that concurrent access can occur. Program memory and data memory are explained in this section. Program memory can be read internally by the user code. The data memory can further be broken down into the general purpose RAM and the Special Function Registers (SFRs). The operations of the SFRs that control the “core” are described below. The SFRs used to control the peripheral modules are described in the section discussing each individual peripheral module.

2.4.3.1 DATA MEMORY ORGANIZATION: The Data Memory is partitioned into multiple banks that contain the General Purpose Registers and the Special Function Registers. Bits RP1 (STATUS<6>) and RP0 (STATUS<5>) are the bank select bits.

Each bank extends up to 7Fh (128 bytes). The lower locations of each bank are reserved for the Special Function Registers. Above the Special Function Registers are General Purpose Registers, implemented as static RAM. All implemented banks contain SFRs. Some “high use” SFRs from one bank may be mirrored in another bank, for code reduction and quicker access (e.g., the STATUS register is in Banks 0 - 3).


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Voice Controlled Wheelchair 2.4.3.2 GENERAL PURPOSE REGISTER: The register file can be accessed either directly, or indirectly, through the File Select Register FSR.

2.4.3.3 SPECIAL FUNCTION REGISTERS: The Special Function Registers are registers used by the CPU and peripheral modules for controlling the desired operation of the device. These registers are implemented as static RAM. The Special Function Registers can be classified into two sets: core (CPU) and peripheral.

2.4.3.4 STATUS REGISTER: The STATUS register contains the arithmetic status of the ALU, the RESET status and the bank select bits for data memory. The STATUS register can be the destination for any instruction, as with any other register. If the STATUS register is the destination for an instruction that affects the Z, DC or C bits, then the write to these three bits is disabled. These bits are set or cleared according to the device logic. Furthermore, the TO and PD bits are not writable. Therefore, the result of an instruction with the STATUS register as destination may be different than intended. STATUS REGISTER (ADDRESS 03h, 83h, 103h, 183h)


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Voice Controlled Wheelchair 2.5 RF 434MHz Tx-Rx:

Figure 2.5.1 : RF 434MHz Tx-Rx

Figure 2.5.2 : RF 434MHz Tx-Rx

2.6 RELAY DRIVER CIRCUIT ULN 2003 The ULN2003 is a monolithic high voltage and high current Darlington transistor arrays. It consists of seven NPN darlington pairs that features high-voltage outputs with common-cathode clamp diode for switching inductive loads. The collector-current rating of a single darlington pair is 500mA. The darlington pairs may be parrlleled for higher current capability. Applications include relay drivers, hammer drivers, lampdrivers, display drivers (LED gas discharge), line drivers, and logic buffers. The ULN2003 has a 2.7kΩ series base resistor for each darlington pair for operation directly with TTL or 5V CMOS devices.

Figure 2.6.1 : Schematic of ULN 2


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Voice Controlled Wheelchair 2.6.1 RELAY:

Relays are remote control electrical switches that are controlled by another switch, such as a horn switch or a computer as in a power train control module. Relays allow a small current flow circuit to control a higher current circuit. Several designs of relays are in use today, 3- pin, 4-pin, 5-pin, and 6-pin, single switch or dual switches.

2.7 MOTORS: An electric motor converts electrical energy into mechanical motion. DC motors drives the wheels of wheel chair.

Figure 2.7 : Working of DC motors

The DC motor has a rotating ligature in the form of an electromagnet. A rotary switch called a commutator reverses the direction of the electric current twice every cycle, to flow through the armature so that the poles of the electromagnet push and pull against the permanent magnets on the outside of the motor. As the poles of the armature electromagnet pass the poles of the permanent magnets, the commutator reverses the polarity of the armature electromagnet. During that instant of switching polarity, inertia keeps the classical motor going in the proper direction.


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Voice Controlled Wheelchair The different direction of motions possible is: 

Forward: Both the motors in forward direction



Reverse: Both the motors in the reverse direction



Left: Left motor stopped/Right motor in the forward direction



Right: Right motor stopped/Left motor in the forward direction



In turn: The motors are in the opposite direction

Figure 2.7.1 : torque in dc motor Department of Electronic & Communication Engineering K.B.N College of Engineering, Gulbarga

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2.8 MICROPHONE: The speech of the user is received by a microphone.This is not a high quality microphone, and in general, the microphone should be a high quality device with noise filters built in. The speech recognition rate is directly related to the quality of the input. The recognition rate will be significantly lower or perhaps even unacceptable with a poor microphone. Therefore it is reason to believe that the performance of this system will increase with a microphone with higher quality.

2.9 CRYSTAL OSCILLATOR: Crystal oscillators are oscillators where the primary frequency determining element is a quartz crystal. Because of the inherent characteristics of the quartz crystal the crystal oscillator may be held to extreme accuracy of frequency stability. Temperature compensation may be applied to crystal oscillator to improve thermal stability of crystal oscillator.

Figure 2.13: Crystal oscillator Crystal oscillators are usually fixed frequency oscillators where stability and accuracy are the primary considerations. For example it is almost impossible to design a stable and accurate LC oscillator for the upper HF and higher frequencies without resorting to some sort of crystal oscillator.


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2.10. FEATURES: •

Glass passivity

•

High maximum operating temperature

•

Low leakage current

•

Excellent stability

•

Available in ammo-pack.

2.10.1 DESCRIPTION:

A two-terminal semiconductor (rectifying) device that exhibits a nonlinear current-voltage characteristic. The function of a diode is to allow current in one direction and to block current in the opposite direction. The terminals of a diode are called the anode and cathode. Rugged glass package, using a high temperature alloyed construction. This package is hermetically sealed and fatigues free as coefficients of expansion of all used parts are matched.


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CHAPTER – 3

WORKING 3.1 WORKING: The speech recognition system is a useful and easy to use programmable speech recognition circuit. Programmable, in the sense that user can train the words (or vocal utterances) he needs the circuit to recognize. This board allows the user to experiment with many facets of speech recognition technology. It has 8 bit data out which can be interfaced with any microcontroller for further development. Some of interfacing applications which can be made are controlling home appliances, robotics movements, Speech Assisted technologies, Speech to text translation, and many more. Robotics has been of interest to mankind for over hundred years. However our perception of robots has been influenced by the media and Hollywood. The vast majority of robots do have several qualities in common. First of all, almost all robots have a movable body. Some only have motorized wheels, and others have dozens of movable segments, typically made of metal or plastic. Like the bones in your body, the individual segments are connected together with joints. This robot is controlled by voice commands. This can be moved forward and reverse direction using geared motors of 60RPM. Also this robot can take sharp turnings towards left and right directions. It uses PIC16F72 MCU as its controller. It uses 12V battery., mainly useful for industrial applications, surveillance applications. This topic gives exact concept of controlling a robot by a voice instruction. The speech recognition system is easy to use programmable speech recognition circuit. Programmable, in the sense that the system to be trained the words (or vocal utterances) user wants the circuit to recognize. This board allows us to experiment with many facets of speech recognition technology. It has 8 bit data out which can be interfaced with any microcontroller. Some of interfacing applications which can be made


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Voice Controlled Wheelchair are controlling home appliances, robotics movements, Speech Assisted technologies, Speech to text translation, and many more. Hence this topic uses a speech recognition application installed in a PC. This application is used through a RS232 port which gives access to the micro controller and the other hardware circuit. A mike is connected to the PC, when we speak a specific command whose respective program is stored in the PC through the mike then our hardware (wheelchair) will move according to the given command. The entire working is further explained with the help of circuit diagram. To reduce complexity we have divided the circuit in following parts – 1. Power supply 2. PC ( speech recognition application ) 3. Motor driving circuit 4. RF transmitter and receiver 5. Microcontroller

3.1.1 POWER SUPPLY: A battery of 9V is used as the power supply. We are using LM 7805 (IC) for 5V dc. This is voltage regulator IC. It has 3 pins. One is called input, second pin is common pin & third pin is output. We can feed 8.5V to 35V unregulated dc at input pin. Input should be greater than 8V for correct regulation. Second pin is common & generally connected with ground (- supply). Third pin is output pin & it gives us 5V regulated dc until input pin is greater than 8V dc. We are using LM7805 voltage regulator IC because we have one micro-controller in our circuit. Its voltage range is 2V dc to 6V dc. So we are using 5V dc as international standard because all digital circuits run on 5V DC.


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Figure 4.1 Circuit diagram of power supply using LM7805

3.1.2 PC (Speech recognition application in VB): Voice controlled wheelchair requires a speech recognition IC known as HM2007, but this IC was not available to us. Hence we are using a speech recognition application which is used through VB for recognizing a voice command and performing the required operation. Visual Basic (VB) is a third-generation event driven programming language and

associated development environment from Microsoft for its COM programming model. Visual Basic was derived from BASIC and enables the rapid application development (RAD) of graphical user interface (GUI) applications, access to databases using DAO, RDO or ADO and creation of Active X controls and objects. A programmer can put together an application using the components provided with Visual Basic itself. Programs written in Visual Basic can also use the Windows API, but doing so requires external function declarations the language not only allows programmers to create simple GUI applications, but can also develop complex applications as well. Programming in VB is a combination of visually arranging components or controls on a form, specifying attributes and actions of those components, and writing additional lines of code for more functionality. Since default attributes and actions are defined for the components, a simple program can be created without the programmer having to write many lines of code.

For using speech recognition application we have used visual basic which provides an important Microsoft speech to text converting tool. This tool plays the most important role in converting a user’s speech command into text and send respective signal to the microcontroller to perform the required operation. Fig. 3.9 shows the window of VB using Microsoft Speech Recognition tool.


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Voice Controlled Wheelchair 3.1.3 MOTOR DRIVING CIRCUIT: A motor driver is a device or group of devices that serves to govern in some predetermined manner the performance of an electric motor. A motor controller might include a manual or automatic means for starting and stopping the motor, selecting forward or reverse rotation, selecting and regulating the speed, regulating or limiting the torque, and protecting against overloads and faults.

All types of engine-driven vehicles from automobiles, airplanes, aircraft carriers and agricultural equipment to ambones may have electric motors to perform a variety of functions. In electric vehicles, diesel-electric vehicles, and hybrid vehicles, electric motors are used to propel the vehicle. The motor controllers in vehicle applications are integrated into the vehicle.

An electric motor controller can be classified by the type of motor it is to drive such as permanent magnet, servo, series, separately excited, and alternating current. A motor controller is connected to a power source such as a battery pack or power supply, and control circuitry in the form of analog or digital input signals.

DC motors are typically controlled by using a transistor configuration called an "H-bridge". This consists of a minimum of four mechanical or solid-state switches, such as two NPN and two PNP transistors. One NPN and one PNP transistor are activated at a time. Both NPN and PNP transistors can be activated to cause a short across the motor terminals, which can be useful for slowing down the motor from the resistance it creates. There are two motors in our wheelchair which drive the two wheels in forward, reverse, left and right directions. The motors are controlled through two identical circuits known as H-bridge. An H-bridge is an electronic circuit which enables DC electric motors to be run forwards or backwards. These circuits are often used in robotics. H-bridges are available as integrated circuits, or can be built from separate components. The term "H-bridge" is derived from the typical graphical representation of such a circuit. An H-bridge is built with four switches (solid-state or mechanical). The first switch is connected from the high voltage bus to the first terminal of the DC motor.


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The second switch connects the second terminal of the DC motor to the low voltage bus. The third switch is connected between the high voltage bus and the second terminal of the DC motor. The fourth and final switch links the first terminal of the DC motor to the low voltage bus. When the first and second switches are closed (and the third and fourth are open) a positive voltage will be applied across the motor between the first and second terminals. By opening the first and second switches and closing the third and fourth switches, this voltage is reversed, allowing reverse operation of the motor. Figure 3.9 shows the circuitdiagram of an H-bridge operating a dc motor.

Figure 3.1.3 Circuit diagram of H-bridge

3.1.4 RF TRANSMITTER AND RECEIVER: A 434 MHz RF transmitter and receiver are used for making the wheelchair wireless. The transmitter is connected to the computer which transmits the signal equivalent to the given command by the user. The RF transmitter is set with the software part using MAX232 while the RF receiver is set on the hardware part of topic. The function of RF receiver is to receive the signals from transmitter and provide serial data to microcontroller to perform the required operation.


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Voice Controlled Wheelchair 3.1.5 MICROCONTROLLER (PIC16F72):

A microcontroller is an important part of any robot, it receives input signal and performs the desired operation. The microcontroller we are using is PIC16F72 for taking the serial data from PC and control the movement of the wheelchair.

This microcontroller is based on RISC (Reduced Instruction Set Computing), it also uses CMOS technology. It has basically 35 instruction sets, also provides direct, indirect and relative addressing modes. The clock input is of 20 MHz frequency and instruction cycle time is 200 ns. It has 28 pins and 3 input and output ports namely port A, port B and port C. The entire working of the circuit is further explained with the help of circuit diagram. In our circuit pin number 8 and 19 are grounded, while pin 1 is connected to a 4.7K resistance and a switch. Pin number 9 and 10 are used to connect the crystal oscillator of 4MHz to give the clock signals. Pin number 20 is connected to high voltage supply Vdc (5V). The pins of port C are used to receive i/p and provide o/p to the H bridge. Pin number 15 is connected to RF receiver to receive i/p data from the transmitter, while pin number 11 and 12 are connected to first H-bridge and so do pin number 13 and 14 to second H-bridge.


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Voice Controlled Wheelchair 3.1.6 CIRCUIT DIAGRAM:

V C C 5V

U 1 2 3 4 5 6 7 9 1 0

Crystal Ocs 4Mhz

1 2 0

R A 0 / A N 0 R A 1 / A N 1 R A 2 / A N 2

R B 0 / IN T R B 1 R B 2

R A 3 / A N 3 / V R E F R A 4 / T O C K I R A 5 / S S / A N 4

R B 3 R B 4 R B 5

O S C 1 / C L K I N

R B 6 R B 7

O S C 2 / C L K O U T R C 0 / T 1 O S O / T 1 C K I M C L R / V P P V D D

S W 1

R C 1 / T1 O S I R C 2 / C C P 1 R C 3 / S C K / S C L R C 4 /S D I / S D A R C 5 / S D O R C 6

5 V

R C 7

R 1 4.7K

5 V

2 1

Motor1

2 2 2 3 2 4 2 5 2 6 2 7 2 8 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8

PIC16F72

RF Receiver

Motor2

Figure 4.4 Circuit diagrams of micro controller and motor driver.

The working of voice-operated wheelchair can be explained in the following stepsStep 1- The very first step requires installing the software used for voice recognition i.e.

VB 6.0 along with the additional Microsoft direct text-speech tool on a computer.

Step 2- After installing the software we check the working of our software part by

speaking through mike, if the front end of VB recognizes the command then it shows a message box in which the spoken command is written. Step 3- Once the speech recognition part is installed and checked then comes the

connecting of RF transmitter to the serial port of PC using MAX232 and a 9V battery is also connected to the transmitter for running it. The transmitter receives serial data from the PC and transmits it. Step 4- Now we connect the 9V batteries to RF receiver, two H-bridge circuits and the

voltage regulator. Now our hardware is ready to receive command and move according to the user.


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Voice Controlled Wheelchair Step 5- Now when the user speaks a command in to mike then a transmitted signal is

received is then it is send to the i/p pin of port C (C4 i.e. 15) and the microcontroller reads the command and compares the values of port C according to the following table.

Operation Forward Backward Right Left

C0 High Low Low High

C1 C2 Low High High Low High High Low Low Table 4-1: Direction of wheelchair

C3 Low High Low High

As the above table describes the various movements of wheelchair due to the high and low values set by the microcontroller to the o/p pins of port C i.e pin number from 11-14 (C0, C1, C2, C3). The pin C0 and C1 of port C are connected to the H-bridge which operates motor1 while pin C2 and C3 are connected to the other H-bridge which controls movement of motor2. Thus the two motors move according to the data on o/p pins of port C and our wheelchair moves in the required direction.


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CHAPTER – 4

CONCLUSION The goal of this topic to develop a speech controlled wheelchair application for the handicapped and physically paralyzed patients. The goals were fulfilled with quite good results. In this case Visual Basic was used, a programming language that is easy to learn and use but yet powerful enough to make wheelchair control systems. With fairly limited code it is possible to reach high wheelchair control performance. The bottleneck of the performance lies on the speech recognition part of the system. For users with a strong accent the performance will not be very high. For people with a good accent, and even for native speakers, it takes a while to learn how to speak to achieve good results.

When this is learned, the speech recognition performance will be quite high, although not perfect. The performance can be increased by training the system to a specific voice and defining a strict grammar were the developer also have in mind what words can be confused. But the security of the system can be increased, for instance by implementing a confirm mechanism. Still much of the performance results depend on the speech recognition programming, which hopefully will improve further.


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REFERENCES

1. Electronic Devices - Robert L. Boylstead and Louis Nashelsky - Pearson Education Publication - 8 th Edition 2. http://www.electronics4u.com/ 3. http://www.projectsabtracts.com/ 4. http://www.techtriks.wordpress.com/ 5. http://www.ideaprojects.com/ 6. http://www.datasheetcatalogue.com 7. http://www.alldatasheets.com


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Voice Controlled Wheelchair

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