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Designing Quadcopter andUsing camera output forcrowdestimation/behaviour.
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Designing Quadcopter and Using camera output for
crowd estimation/behaviour.
Students Project Guide
Devesh (136/10) Mrs Farida Khurshid
Nikhilesh Sharma (185/10) Associate Professor
Shubham Pandey (457/10) Deptt. of Electronics and Communication
Akhilesh Koul (334/10) NIT Srinagar
Deptt. of Electronics and Communication
NIT Srinagar
Abstract:
Our project will be in two stages. First stage will be: building a quadcopter that
has manoeuvring capability that can move up, down, left, right, forward and
backward. The control of the quadcopter will be done using RF module i.e.
Receiver and Transmitter Module. Further the stabilization will be done using
sensors like gyro, accelerometer mounted on the board. The second stage will be:
using camera output for crowd estimation. This can be done in two ways, first
recording the data during the in-flight and processing it post flight and the second,
video transmission using live feed from the camera and processing it in real time
mode.
Quadcopter:
Quadcopter is a quad rotor based helicopter that is lifted and propelled by four
rotors. Unlike helicopters they use symmetrically pitched blades. Control of
vehicle is achieved by altering the pitch and/or rotation of one or more rotor
discs, thereby changing its torque load and thrust.
The quadcopter design was chosen for this project due to its high degree of
stability and lifting power. The design consists of a symmetrical array of four
motors commonly attached with an ‘X’ shaped frame. The rotation direction of
the motors is alternated, so opposite motors spin in the same direction, to
counteract the reaction torques produced by the rotors. This design eliminates
the need for a yaw stabilizing rotor commonly used on helicopters.
The use of multiple rotors allows the vehicle to have a large lift capacity. For our
design we will aim to build a quadcopter with a lifting force that is double its own
weight.
Applications of quadcopter:
Research platform
Quadcopters are a useful tool for university researchers to test and evaluate new ideas in a number of different fields, including flight control theory, navigation, real time systems, and robotics. In recent years many universities
have shown quadcopters performing increasingly complex aerial maneuvers. Swarms of quadcopters can hover in mid-air, in formation, autonomously perform complex flying routines such as flips, darting through hula-hoops and organise themselves to fly through windows as a group.
Military and law enforcement
Quadcopter unmanned aerial vehicles are used for surveillance and reconnaissance by military and law enforcement agencies, as well as search and rescue missions in urban environments.[22]
Commercial
The largest use of quadcopters has been in the field of aerial imagery although, in the USA, it is currently illegal to use remote controlled vehicles for commercial purposes. Quadcopter UAVs are suitable for this job because of their autonomous nature and huge cost savings. Capturing aerial imagery with a quadcopter is as simple as programming GPS coordinates and hitting the go button. Using on-board cameras, users have the option of being streamed live to the ground.
Figure 1. Prototype
Figure 2. Reaction Torque
COMPONENTS DESCRIPTION:
Brushless DC Motor: It will be used to rotate propellers which will subsequently
provide thrust, needed to lift the system. Brushless motors are used because they
provide maximum RPM.
Specifications :
Weight : 49gms
Get 700 gms Thrust
Prop. : 9x4.7E
LIPO : 2cell 7.4v
Operating voltage : 7.1v
Current Drawn at load : 15A
ESC : 20 amp
Electronic Speed Controller (ESC): They will be used to control the RPM of motor,
needed in proper manoeuvring. They are driver cum controller circuit which
consist of an on-board processor, firmware and FET’s (for switching, to provide
Pulse Width Modulated signal).
Specifications:
Weight:18g
Size:32x47x4mm
Cells:2-3S(AutoDetect)
MaxCurrent:18A
Burst:20A
Sensor: once the system is airborne it will need auto stabilization which will be
provided by gyro. Gyro gives output in the form of pitch, yaw and roll. These three
parameter will be processed in MCU and the motors will be controlled
accordingly.
Propellers: These are blades, connected to motor to provide thrust.
Battery: We shall need Lithium polymer battery to power all the four motors
since this battery provides optimum amps and power to drive the motor for a
longer flight time as compared to other batteries.
Figure 3. Quadcopter System Overview
Figure 4. Motor Control using ESC
Transmitter and receiver:
RF Module: As the quadcopter need signal for its manoeuvring, it needs RF to
transmit data(control). We shall need Rx-Tx module to send control signals
(wirelessly) to the quadcopter for its movement.
Specifications:
Receiver Transmitter
Product Model: XY-MK-5V Product Model: MX-FS-03V
Operating voltage: DC5V Operating Voltage: 3.5-12V
Receiving frequency: 433.92MHZ Transmitting frequency: 433M
MCU: The data from RF module, Sensor module are to be processed and output
signal is to be fed into ESC for motor control. All these processes and data
manipulation will be done in microcontroller unit.
Video Recording:
The choice of video system is one of the most crucial decisions for the project.
The camera needs to be light enough so that the UAV can fly unabated and
compact enough so that it does not interfere with the landing gear and rotors.
The height for our project is 50-100m.
Video Camera:
There are many different options for the camera. One of the first solutions is to
mount a camera to the fuselage of the quadcopter which would be able to
produce a high resolution image.
We will be using a CMOS camera for image acquisition which uses a CMOS
imaging chip . A CMOS imaging chip is a type of active pixel sensor which is
an image sensor consisting of an integrated circuit containing an array of pixel
sensors, each pixel containing a photo detector and an active amplifier made
using the CMOS semiconductor process. Extra circuitry next to each photo sensor
converts the light energy to a voltage. Additional circuitry on the chip may be
included to convert the voltage to digital data.
Figure 5. CMOS Camera
VIDEO ANALYSIS:
The video analysis process consists of processing the acquired video frames to
achieve the desired result which in this case is crowd estimation. Firstly, we need
to stitch the various images acquired to form a mosaic and then further
processing it assess the crowd density in a particular area. The reason behind
creating a mosaic is to increase the area under consideration.
The algorithm used in the crowd estimation is our project is canny edge detection
employing which we can detect and differentiate members of the crowd. Then
further creating the contour around the detected edges we can easily count the
number of people.
Canny Edge Detection:
In the canny edge detection algorithm, it tries to assemble the individual edge
candidate pixels into contours. These contours are formed by applying upper and
Figure 6. a) and b) Two different Images with some overlap region, c) Feature Matching using SIFT, d) Stiched Image
lower threshold to the pixel. If a pixel has a gradient larger than the upper
threshold, then it is accepted as an edge pixel; if a pixel is below the lower
threshold, it is rejected. If the pixel’s gradient is between the thresholds, then it
will be accepted only if it is connected to a pixel that is above the high threshold.
Limitations:
Though this method helps in differentiating the people in a crowd but this
increases the contour area of each individual by adding the area covered by the
shadow of the individual as well. This leads to miscalculations which is not
tolerable.
To overcome this issue, we can use crowd density estimation techniques.
Figure 7. Canny Edge Detection, selecting high and low threshold
Figure 8. In both these examples above, succesfully able to draw contours, but because of the shadows, it is giving wrong results.
Estimated Cost:
Components Price(INR)
Frame 700
Brushless Motor(4 No’s) 4x1000
Electronics Speed Controller(4 No’s) 4X700 Sensor(Gyro) 1200
Propellers(4 No’s) 4x100 Battery (LiPo) 600
RF Module 350
MCU + PCB + Other IC’s - Camera and Other Accessories -
Miscellaneous 3000
Total 13050