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