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Usage of the Hough Circle Transform on a robot to detect yellow balls.

3.0 hardware introduction

This project had a two part goal: 1. Understand the Hough Transform and be able to detect circles using from-scratch code and 2. Implement the Hough Transform on hardware to create a robot that can detect yellow balls. This section will explain that hardware implementation in detail.

The robot

The Robot
An image of our robot with important system parts labeled.

The hardware that we used for this project was largely provided by the Rice Robotics Club which uses tools from Vex Robotics. The robot four-wheeled using Mechanum wheels which allow for strafing if they are rotated in the proper directions. To drive the wheels, the Vex Cortex onboard computer runs code in C to drive each of the four motors at the proper power levels. The cortex also receives information from a Gyroscope in order to determine what angle the robot is facing. Finally, a Raspberry Pi runs code in Python with a PiCamera to run the ball detection algorithm which transmits data to the Cortex using the UART protocol. Below we can see the block diagram for the robot's system.

Overall hardware system

Overall Hardware System
The system in its entirety. The Raspberry Pi system and Vex Cortex system are explained in detail in further sections.

3.1 raspberry pi system

We will now dive into the inner workings of the Raspberry Pi ball detection algorithm. The overall objective of the Raspberry Pi is to use images taken from the PiCamera and determine an angle for the robot to turn to as well as a single bit determining whether or not a ball is seen.

The raspberry pi system

Pi Detection System
Image capture comes in through the PiCamera hardware. The output is always a 5 character string over UART to the Cortex.

The first thing the pi does is capture an image using the PiCamera. This image capture can only be done as fast as the code can run. At 360x240 pixels, the Pi can capture images at roughly 5 frames per second. Increasing that resolution decreases the frames per second and also decreases the speed that it can detect the ball. Howevever, increasing the resolution also increases the size of the ball that can be detected. A greater resolution means that the Raspberry Pi algorithm can detect balls that are either smaller or further away. At the resolution we chose (360x240) the pi can reliably detect a ball that is 2 or 3 feet away.

Once the image is captured, we need to filter out for the color yellow. This is done quite simply in the HSV (hue/saturation/value) colorspace. In good lighting, the color yellow falls in the Hue values of ~30-60, the Saturation values of ~80-255, and the Value values of ~80-255. More precise values for yellow detection can be used for more accurate results, but they depend heavily on lighting conditions on the room. For this reason, the program needs to be re-calibrated every time it enters new lighting condition. In the future we could have an auto-calibration sequence for the robot to determine these values, or simply preset modes for different lighting methods.

Questions & Answers

what does the ideal gas law states
Joy Reply
Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
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Source:  OpenStax, Hough transform object detection. OpenStax CNX. Dec 16, 2015 Download for free at http://legacy.cnx.org/content/col11937/1.1
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