M S Ramaiah Institute of Technology, INDIA presents
“Moksha”Unmanned Ground Vehicle
Planning Design Implementation Integration Testing
Fig: Stages of Development of Moksha – UGV
• Better stability and drive control in terrain conditions.• Ramp climbing ability.• Can take load of 150 kg.
Split Frame Chassis
• Laser cut mild steel frame withwelded joints.
• Steel platform for laptop &compartment for payload.
• CPVC mounts for camera andGPS.
• Slide out battery box under theframe.
• Hood for solar panels.
Fabrication
Power Supply Board and Solar Panels
• Connectors that can handle power surge.• Voltage regulator IC 7805 for providing constant 5v DC supply.• Use of solar cells for recharging the batteries and promoting renewable
energy sources.
Material Mild steel
Length 3 feet 10 inches
Width 2 feet
Height 3 feet
Wheels 4
Motors 2(24 VDC,1.8 Amax,120 W)
Weight 62 Kg
Sensors Used: 1. Camera – 5 MP Webcam
2. SONAR
3. Garmin 18x GPS
Motor Controller: RS160D
Motors (24VDC 120W)
Power Supply System
Battery
Chassis
Safety:
Mechanical stop, Wireless E-Stop, Manual Brake
Hardware Specifications
LV-MaxSonar-EZ1
The LV-MaxSonar®-EZ1™ is The EZ1™ is an excellent choice for use were sensitivity is needed along with side object rejection.
The sensor offers three standard outputs (analog voltage, serial data, and pulse width)
The LV-MaxSonar®-EZ products also operate with very low voltage from 2.5V to 5V with less then 3mA nominal current draw.
Garmin 18x USB
The GPS 18x is a, high-sensitivity GPS sensor for use in automotive, fleet vehicle, and electronics applications that require a small, highly accurate GPS receiver.
Supports non-volatile memory for storage of configuration information, a real-time clock and raw measurement output data in NMEA 0183 format.
RS 160D
The motor control used is the RS160D by Robot-Solutions, LLC.The RS160D servo uses custom software to implement a 2.5 channel high-powered servo system.
The RS160D operates in the PWM mode communicating serially with the processor through a RS232 cable.
1. The different devices on the UGV are controlled by a C++program which includes an algorithm which uses thedata from the sensors.
2. The different devices are connected to the processorusing the USB ports which are interfaced to the devicesusing USB to RS232 converters.
3. This is done since the data is exchanged between theprocessor and the sensors and motor controller serially.
4. From the motor controller, output is sent to theactuators to move the robot.
The camera is placed at an angle facing the ground in front of the vehicle at about 3 feet height
The processing of image is done as shown below:
• First the RGB image is converted to a gray scale image.
• The gray scaled image is processed using Canny algorithm to detect the edges in the image.
• Then the resulting image is processed using Hough (Probabilistic) transform to detect only line segments in the image.
Black & White Image
After Canny Edge detection
Line Detected using Hough Transform
1. The data from the GPS isextracted using serial data transferfunctions.
2. The destination point is taken bythe program and the area aroundthe GPS is divided into 4quadrants.
3. The current location of the GPSlies in one of the 4 quadrants andbased on the quadrant the UGV islocated at, the direction and theturning angle is calculated anddata is sent to motor controller.
1. The co-ordinates are obtained from the Garmin 18x USB, and then we manually input the destination co-ordinates into a sub-controlling program, which then continuously calculates the relative angle between the destination point and the present direction of the vehicle.
2. It decides, first, which point is closest to its present location, selects that point, and then makes its angle calculations as follows using “Haversine Formula”.
3. This data is returned continuously to the main controlling program, where decisions are made.
R = Earth’s radius (mean radius = 6,371km)
Δlat = lat2− lat1
Δlong = long2− long1
a = sin²(Δlat/2) + cos(lat1).cos(lat2).sin²(Δlong/2)
c = 2.atan2(√a, √(1−a))
d = R.c
C++ is used to send data serially instead of HYPERTERMINAL. Data is sent in ASCII format from the processor. The RS160D is a 2 channel controller. Each channel controls 2 different motors(right and left).Data is sent as : “@0sm1” sent as "(right and channel controls one motor. One of
the channels is used to control the left motor and the other motor selects mode 1 i.e., PWM mode
“@0sj0” selects serial communication mode“@0st255” torque control
LEFT MOTOR RIGHT MOTOR UPSHOT
@0st120 @0st120 BOTH MOTORS OFF
@0st130 @0st130 LOW VOLTAGE,VEHICLE MOVES
WITH JITTER MOTION,NOT
STABLE
@0st170 @0st170 VEHICLE MOVES STRAIGHT
SMOOTHELY AT AVERAGE SPEED
OF 2 MPH
@0st170 @0st140 VEHICLE MOVES RIGHT
@0st140 @0st170 VEHICLE MOVES LEFT
1. The implementation of the GPS is based on C++ code to provide high level functions.
2. We are using a Brute force algorithm. This algorithm evaluate the safest, shortest path to a given location based on cost calculations.
3. Sub-controlling program, continuously calculates the relative angle between the destination point and the present direction of the vehicle.
PRN 12
PRN 2
PRN 8
PRN 18
Roaming
GPSReference
Station
Differential Correction
Pathway
Split frame chassis for better stability and drive control.
Strong steel frame that can take a weight of 150kg.
Rear wheel drive powered by powerful 24V 180W motors controlled by RS 160D Motor Controller.
Very small turning radius.
Max Speed of 5MPH.
Compact size: Length 3ft Width 2 ft Height 4ft.
Sensors Used: LV Max Sonar EZ1
Garmin 18x USB
USB PC Camera
Simple and efficient code using Visual C++ and Open Computer Vision library.
Image Processing based on Hough Transform.
GPS based navigation code capable of driving to specified locations.
Hardware Specifications: Software Specifications:
Safety Features: Mechanical stop, wireless E-Stop
and Manual Brakes for enhanced safety.
REFERENCES
Real-Time, Multi-Perspective Perception for Unmanned Ground Vehicles- Anthony Stentz, Alonzo Kelly, Peter Rander, Herman Herman, Omead Amidi, Carnegie Mellon University
The Intelligent Ground Vehicle Competition, Rules and Regulations -igvc.org/IGVCRules2011V5updatedflagpartnumbers.pdf
IGVC Design Reports- igvc.org/reports.htm
The Open CV 2.1 C++ approach -opencv.willowgarage.com/documentation/cpp/index.html
RD 160D by Robot Solutions- robot-solutions.com/RS2/RS160D-Manual.pdf
Distance betwwen latitude/ longitude points using Haversine Formula-movable-type.co.uk/scripts/latlong.html
Garmin 18x OEM Manual- delcom-eng.com/downloads/ USBPRGMNL.pdf
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