drdo student robot competition - iiit hyderabadbasil.george/files/drdo.pdfdrdo student robot...

DRDO Student Robot Competition

International Institute of Information Technology - Hyderabad

Team IIITTeam IIITTeam IIITTeam IIIT----HyderabadHyderabadHyderabadHyderabadDRDO 2010

1

Introduction

2

The TeamNo. Name Course Position Contact details

1 Nikhil Soni Undergraduate Team Leader [email protected]

2 Basil George UndergraduateMember, Electronics

[email protected]

3 Abhishek Bhatia UndergraduateMember, Mechanical

[email protected] Abhishek Bhatia Undergraduate

[email protected]

4 Mrityunjay Bhadauria Post-graduateMember, Vision navigation team

[email protected]

3

Organisation Chart

Team MentorMr. Ravi Prasad

Faculty Advisor

Electronics DesignTeam:

Lead : Nikhil SoniBasil GeorgeFaculty Advisor

Dr. K. Madhava Krishna

Team LeaderNikhil Soni

Alternate Team LeaderMrityunjay Bhadauria

Basil George

Mechanical Structure:Abhishek Bhatia

Vision Navigation Algorithm:Mrityunjay Bhadauria

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Introduction

Systems Overview

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Mission Summary

ØAutonomous All Terrain Vehicle: •Travels on sand, gravel, corrugations, ramp. •Should be able to climb the steps of particular height and width. •Should be able to move on a slope of maximum 15 degrees.

Ø350 m of vision navigation with obstacle avoidance: •Should be able to detect and move between two lines of alternate black and •Should be able to detect and move between two lines of alternate black and yellow stripes. •Should be able to detect and avoid obstacles in-between the path.

Ø150 m of GPS based navigation with obstacle avoidance. •Should be able to traverse between given GPS waypoints. •Should avoid obstacles in-between the path.

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Overview of Changes since PDR

ØMechanical Design:•4 wheel drive changed to 6 wheel, with flexible front portion.•The front portion is fixed to the back using aluminum door hinges, which provides a great flexibility to the structure.•This rocker-bogey-inspired structure is fabricated for efficient stair climbing and flexible all terrain navigation.flexible all terrain navigation.

ØCommand and Data handling subsystem:•Main processing unit changed from Beagle-Board (rev.C3, ARM Processor + DSP Processor) to INTEL ATOM NEBOOK for better real time response characteristics.

ØSensor Subsystem:•Stereo Vision Camera is changed to single VGA USB Camera.

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System Context Diagram

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Physical Layout

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Introduction

Systems Overview

Sensor Systems Design

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Sensor Systems Overview

Sonar1

(LV-MaxSonar –EZ0)

Laptop(Lenovo Ideapad S-10

GPS sensor( SIRF -StarIII GSC3f/LPx-7989)

Microcontroller1 (ATmega16)

Sonar2

(LV-MaxSonar –EZ0)

(Lenovo Ideapad S-10 Netbook)

Digital Compass Module(CMPS03)

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Summary of Sensor Procurement

(a) GPS Procurement Status

Item Description

Component GPS Sensor iWave-GPS Module with PatchAntenna Chip manufaccture:

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Antenna Chip manufaccture: Sirf.

Vendor iWave Systems Technology Pvt. Ltd Bangalore.

Quantity 1

Model Procurement IIIT-H Robotics Lab

Unit Cost 4590 Rs.

Comments -


(b) Sonar

Item Description

Component LV-MaxSonar –EZ0

Vendor Nex Robotics Mumbai.

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Quantity 2

Date of Order September 10, 2010

Date of Delivery September 16, 2010

Unit Cost 1296 Rs.

Total Cost 2592 Rs.

Comments -


c) Compass

Item Description

Component CMPS03


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Quantity 1

Model Procurement IRL

Unit Cost 1400Rs.

Comments -


d) Camera

Item Description

Component Logitech USB VGA Camera

Vendor Croma, Hyderabad

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Vendor Croma, Hyderabad

Quantity 1

Unit Cost 1400Rs.

Comments -

GPS Summary

Manufacturer Model Dimensions Accuracy Mass Power/voltage

SiRF StarIIIGSC3f/LPx-7989

Length:27mm Width: 23mm

5m 10g 75mw/3.3v

SiRF GSC3 GPS Sensor

• It works at 3.3 V , which we already generated for other requirements using buck converter. Hence it reduces our effort in generating any other voltage. •It has a 20 receiver which was giving a resolution upto 3 m, which was sufficient for our requirement.

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GPS Measurement Processing

• Four formats of Data (GGA,GSA,GSV,RMC) being received of NMEA protocol through USART to USB adapter.

Receive Extracted values and use it in

Receive GPS valuesand store in array

Read array and Parse relevant data in our case it in

Data packet buffer

and store in array data in our caseGPRMC

Data Frame Format/StructureRecommended Minimum Data (RMC)

$GPRMC,hhmmss.status,latitude.N,longitude,E.spd,cog,ddmmyy,mv.mvE,mode*cs<CR><LF>

$GPRMC suits our requirement of receiving latitude, longitude, speed, number of satellites tracked and Date-Time.

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Sonar Range Finder Summary

Product Type Operates in region Accuracy

LV-MaxSonar –EZ0(Sonar Range Finder)

Digital 0 – 254 inches(6.54 m)

+-1Inches

Sonar/Range Finder

•This sonar sensor is selected to fulfill the need of obstacle detection and due to its range finding capability along with the obstacle detection we can also find the exact range of the obstacle which could be very useful for the defence purposes.

•Another fact about using this sensor is that it is very simple to Use, is low cost and gives stable and reliable data.

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Sonar Range Finder Measurement and Processing

Accept the Analog values from the Collect Continuous Converting the values from the

ADC and convert it to Centigrade from

Digital values obtained

Collect Continuous analog data from

Sonar Range Finder Sensor into the microcontroller.

Converting the Analog voltage value

into digital calibrated value

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Sonar Range Finder Measurement and Processing(Range shown on 1-foot Grid to various diameter dowels)

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ProcessingProcessingProcessingProcessing

Compass Sensor Summary

Model Accuracy Mass Power/voltage Dimensions A/D

CMPS03(Philips KMZ51 magnetic field sensor)

1 degrees 50g 0.5ma/5v 2*2cm D

CMPS03 Compass Sensor

• I2C Interface.• Less in weight and size.• Works at 5 V , which is generated for other requirements too.• Digital in nature, thus easy to use with Microcontrollers, directly gives digital magnetic reading.

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Camera Sensor Summary

Model Field of View(FOV)

Mass Interface Resolution

Logietch USB Camera (VGA)

58 degrees 100g Universal Serial Bus

(USB)

.3 megaPixels

Logitech USB Camera

• USB Interface.• Less in weight and size.• Low Resolution, easily fulfills our requirements.• Images easily processed/segmented by the processing unit.

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Sensor System Testing Overview

GPS • GPS data was compared with GPS sensing units to compare accuracy.

Sonar

•• Sonar data was compared by keeping the obstacles at various places, checking their distance with a measuring tape and then Sonar

readings.

distance with a measuring tape and then comparing that distance with the sonar

readings.

Compass • Compass data was compared by an original magnetic compass for accuracy.

GPS Test Results

Location Latitude Longitude Satellites

Mobile GPS Our GPS Mobile GPS Our GPS Mobile GPS

Our GPS

1 17°26’43.09” 17°26’73.15” 78°21’1.4” 78°21’02.08” 10 8

2 17°26’47.3” 17°26’78.68” 78°20’58.2” 78°20’97.69” 8 7

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Sonar Range Finder Sensor Test Results

S No. SonarSensor Reading

ActualReading

Error (%) Source of ActualReading

1 21.4 cm 21 cm 1.9 Scale

2 41.8 cm 40 cm 4.5 Measuring Tape

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Compass Sensor Test Results

S No. SonarSensor Reading

ActualReading

Error (%) Source of ActualReading

1 326 degrees 324 degrees

0.8 Iphone 3GS built in compass

2 40 degrees 41 degrees 0.4 Iphone 3GS built in compass

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System overview: Interface level

Dual Core Intel Atom

@1.86GHzMCU 1 : Sensor collection

ATmega16 @ 12 MHz

MCU 2 : Motor control

ATmega16 @ 8 MHz

iWave

USB-UARTUSB-UART

USB-UART

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MHz MHziWaveGPS

CompassLeft

SonarRight Sonar

LeftMotors

Right Motors

Set PWM and rotation logic

Motor driversADC ADCIIC

Introduction

Systems Overview


Mechanical Systems Design

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Mechanical Systems Overview

Ø The mechanical subsystem consists of the chassis along with the motors and motor drivers. The mechanical design is inspired from the rocker-bogie suspension system used in Mars rovers.

Ø The design is of a six-wheel drive. The chassis consists of 2 parts: a

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Ø The design is of a six-wheel drive. The chassis consists of 2 parts: a flexible front portion with 2 wheel’s which Is hinged on a back portion to which 4 wheel’s are attached as shown in the figure:

Mechanical Structure

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Dimensions:

Ø Wheel diameter: 8inches keeping in mind the maximum step height.

Ø Length of front portion: 30cms. Ø Length of back portion: 50cms.Ø Length between front and middle

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Ø Length between front and middle wheel = 30cms.

Ø Length between back and middle wheel = 32cms.

Ø Width: 38cms.Ø Weight: 15kg, along with motors and

Wheel’s.

Chassis negotiating a slope

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Introduction

Systems Overview



Command and Data Handling

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CDH Overview

This subsystem deals with the processors used in the system, data rate estimation, communication configuration and various protocols employed for inter-processor as well as

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processor-peripheral device communication.

CDH Overview

• Should implement image processing algorithms in real-time.

• Should handle sensor-data fusion in real-time.

• Require an ADC interface with at • Require an ADC interface with at least 2 ADC ports for SONAR interface.

• Require an I2C interface for digital compass interface.

• Require 1 UART port for GPS interface.

• Should handle power estimated by power budget.

Criterion for microcontroller

selection

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Processor SelectionAtmega16• On-chip flash memory: 16 kbytes

• EEPROM: 512 bytes

• Internal SRAM: 1 kbyte

• 8 channel 10 bit ADC

• I2C, programmable USART interfaces

• 4 PWM channels, 2 8 bit timer/counter, 1 16 bit timer/counter

• 32 programmable I/O pinsOther Processor Considered:

• Atmega 16 : Only one USART ; Less number of I/O ports• 8051 family : Maximum Clock frequency up to 12 MHZ ; Less Memory

Reasons for choosing Atmega 16:

• Meet all the requirements for our purpose • Can Handle Power requirements• Familiar with the Atmel microcontrollers as AVR programming are included in our syllabus

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Processor Selection

Intel Atom processor is very suitable for mobile robotics applications because its small foam factor and high battery life. The Lenovo Ideapad S10 chosen by us has the following features which makes it suitable for real-time processing include:1.86GHz processor1.86GHz processorRAM: 1GB, DDR3RAM frequency: 1.33GHz3 USB portsOther Processor Considered:

• Though TI Beagleboad's dual core of ARM and DSP was initially considered as the main

processing unit, we discarded it due to its low real-time computation power and higher

delays involved in implementing image processing algorithms. Another reason was its low

community support which made our progress very sluggish.

Other options considered TI Beagle Board:

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DATA RATE Estimation

Ø GPS sampled every 1 second and a frequency of 1 HZ.Ø ADC interfacing(Battery Voltage, Temperature and Pressure)

sampled each at 50 kHz ( necessary for proper functioning of sampled each at 50 kHz ( necessary for proper functioning of ADC interface in ATMega128) .

Ø Accelerometer interfacing at 100Hz.Ø Data sent at every 5 seconds or 0.2 Hz with baud rate of

57600 bps.

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Data Package Definition

Characters Definition

hhmmss Data time tag in hours , minutes and seconds

AAAA.aaaa Cansat latitude

N END of latitude data

BBBB.bbbb Cansat Longitude

W END of longitude dataW END of longitude data

hh.hh.. Cansat GPS altitude

Ab Number of satellites tracked in decimal

hh.hh.. Altitude via non GPS sensor(meters)

tt Air temperature ( 1 degree resolution)

vv.v Battery voltage

Total estimated character data including comma delimiters and headers: 60 bytes

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Inter processor Communication Overview

The data flow between the various subsystems is as follows:

1. MCU1(ATmega16) collects data from compass and sonar’s.

2. Netbook sends get_sensor_data flag “aaa” to MCU1 using USB-USART link, requesting the latter to send the sensor data, raising the get_sensor_flag.

3. MCU1 acknowledges the get_sensor_data flag by sending “bbb” to the netbook, again through USB-USART link.

4. MCU1 sends 5 data packets containing sonar and compass data. Netbook stores this data in arrays.

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4. MCU1 sends 5 data packets containing sonar and compass data. Netbook stores this data in arrays.

5. MCU1 sends the transmission_complete flag “eee” indicating the completion of data transfer.

6. Netbook receives “eee” and stops reading from the serial port(USB).

7. Netbook takes data from GPS through USB-USART link and from camera through USB.

8. Sensor data fusion and algorithm implementation happens in the netbook. Algorithm is also implemented.

9. The desired locomotion information is passed on to MCU2 (Atmega16) which generates 2 PWM signals, one for motors of each side, which is passed to the motor driving circuitry, thus moving the robot.

Introduction

Systems Overview




Electrical Power System Design

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EPS Overview

Laptop Battery

MCU 1 : Sensor collection

ATmega16 @ 12 MHz

MCU 2 : Motor control

ATmega16 @ 8 MHz

iWave GPS

Compass

Motor driving

USART to USB

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iWave GPS ModuleLeft

Sonar

Right Sonar

Motor driving unitLinear

Regulator 5V

7.4V Lithium Polymer (Li-Po)

Battery

12V Lead Acid Battery

Powered from the Laptop

Battery (Through USB)

EPS Summary/Budget

Type Voltage/Power Qty Purpose

Lithium Polymer(LiPo) 7.4V/2.2Ah 1 Power logic circuitry

Lead Acid 12V/7Ah 2 Power motors

Summary:

Budget:

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Component Voltage (V) Current (mA)

Power (mW) Qty Time of usage (%)

SONAR 5 3 15 2 100

Compass 5 25 125 1 100

GPS 3.3 22.7 72.6 1 100

MCU1(12MHz) 5 16 80 1 100

MCU2(8MHz) 5 12 60 1 100

Motor driver 12 1200 14400 6 100

Budget:

EPS Requirements

Ø Logic circuitry:• Power required P1 = 295mW• Time before battery drains out > 37

hours

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hours Ø Motor driving unit:

• Power required for each lead acid battery P2 = 43.2W

• Time before the batteries drain out = 2 hours

Get LAT and LONG from

GPS

Calculate distance and Bearing (w.r.t. N) to destination

GPS waypoint

Haversine Formula

If(bearing-heading)>threshold

Turn left(till sonar shows no obstacle),

move

Turn right(till sonar shows no obstacle),

move

STOP(Destination

achieved)

If(distance)<threshold

Orient robot towards bearing

If(bearing-heading)>threshold

Move straightstate

else

else

move straight(short

period)

move straight(short

period)

If(Right sonar detects obstacle)

If(Left sonar detects obstacle)

else

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Introduction

Systems Overview


Descent Control Design



Electrical Power System Design

Conclusions

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Conclusion

• Though we were lacking in the mechanical front (since our college does not have mechanical branch), we managed to build a robust robot which could navigate sandy and gravel terrains and uneven surfaces with ease.

• We developed and implemented the complete algorithm • We developed and implemented the complete algorithm within the short time-limit given.

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