Electrical PPT

Report
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• CanSat Is a Simulation of a Real Satellite
• It Performs a Mission and Collects Data
• Typical Missions Can Be Atmospheric Measurements, Video
• Capture, Picture Taking, Communications, or Navigation
• The Missions Can Be Simple or Complex
• The Only Requirement Is that the Mission Must Fit in a Twelve Ounce Soda Can
• This Program will introduce you to
How CanSat is Built
• It Includes most subsystems found in Satellites
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• CanSat Shall Be Built to Fit in a Standard Soda Can–
• Diameter Is 130+/- 2 mm
• Weight is usually less than 700 gms.
• No Parts of the CanSat Shall Extend Beyond the Surface of the Soda Can Until
Deployed
• CanSat Shall Operate off of Battery or Solar Power
• CanSat Can Use Communications(usually RF communications)
– Antennas Should Be Flexible.
• A Parachute Shall Be Properly Secured to One End of the CanSat.
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• CanSat Is Launched on a HighPowered Model Rocket
– The Rocket Is 4” in Diameter and
About 7’ Tall
– Capable of Reaching Over a Mile in
Altitude
– CanSat Is Stowed in the Upper
Airframe Below the Nose Cone
• The Rocket Is Launched and When It
Reaches Apogee, the Rocket Breaks
Apart to Eject the Main Parachute
– This Causes the Upper Portion of
the Rocket to Point Down
• The Nose Cone Will Fall Out and the
CanSat Will Fall Afterwards
• The Parachute Brings the CanSat
Gently Back to Earth
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• “Satellite is an object which has been placed into orbit by human endeavor” Wikipedia
• “An artificial body placed in orbit round the earth or another planet in order to
collect information or for communication” – Oxford Dictionary
• Various Definitions for satellites have been given.
• Main concepts for the satellite –
• Orbit around the planet.
• Collects information for sending back to ground station.
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• A Satellite Is Made Up of Six Major Subsystems:
• Power Subsystem
• Data Handling Unit/Ground Control Systems
• Communications Subsystem
• Sensor Payload or Subsystems
• Structure
• Attitude Control Subsystem
• Following slides will explain each subsystem in larger detail and will use <satellite
name> as reference
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• The Power Subsystem Provides Electrical Power to the Satellite. Usually,
this is provided using solar panels.
• Solar Panels Are Comprised of Solar Cells, i.e., Semiconductor Devices
Called Photovoltaic.
• Designers Select the Types of Solar Cells to Meet Their Power Requirements,
Budget, Mass and Size.
• Various types of Batteries used in the power system are –
• Ni-Cd.
• NiH2
• Li-Ion.
• The main precautions required in the design of the power system is the fault
detection unit.
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• The Data Handling Unit (DHU) Is a Computer That Controls the Flow of Data
and Instructions.
– It Controls Payloads and Collects Data From the Payloads
– It Accepts Commands Received by the Communications System and Sends
Data to the Communications System for Transmission to the Ground Station
– It Is the Brains of the Satellite.
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• The satellite usually contains a radio receiver for transmitting data to the ground
system and receiving commands from the ground station.
• The Spacecraft Has a Transmitter Used to Send Telemetry (i.e.,
the Name for Data Sent or “Down-Linked” From the Spacecraft).
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• Payloads on a Satellite Are Generally Some Type of Sensor
• It Can Be a Radio Receiver Designed to Detect Certain types of
Signals
• It Can Be a Camera Used to Take Pictures of the Earth in Various
Light Spectrums.
• It Can Be Radiation Detectors, or Any Type of Sensor to Detect
Something.
• The sensors are responsible for the navigation and control system.
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• The structure of satellite is generally made of Al or other light-weight
material.
• Attitude Control Systems Allow the Orientation of the Spacecraft to Be
Controlled.
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•Time Limit: 45 minutes
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Electrical
Subsystem
Mechanical
Design
Software
Analysis
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Kill
switch/signal
Buzzer(5V)
GPS(3.3V)
Motor
Driver(3.3V)
5V
CanSat
Batteries
9V
Voltage
Measurement
Hardware(9V)
9V
Arduino
(9V)
5V
9V
on/off
Motor(9V)
Motor Driver(5V)
3.3 V
SD card(3.3V)
P&T
Sensor(3.3V)
Radio
Transceiver(3.3V
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• The power budget is the allocation of power to be consumed by the components
of the system.
• This requires the analysis of the power requirement of each of the components
and is an integral part of the design of the power system.
• This is required to determine the distribution of power and total power required in
the system.
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• The Antenna selection is done on the basis on Link Budget.
• Link Budget equation –
PRX = PTX + GTX + GRX – LTX – LRX – 20log(4πd/λ)
•
•
•
•
P: Power
G: Gain
L: loss in transmission or receiver
The last term accounts for channel loss
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BMP 085 (T&P
sensor)
Sampling rate: 50 KHz
Buzzer
Gather
Data
Transmit Data
to Ground
Read GPS Data
GPS Data
(Sampling Rate: 1
Hz)
Impact
Measurement
MMA 7361
(Accelerometer)
(Sampling rate: 100
Hz)
after payload
has landed
SD Card
FSW written
on
Arduino Nano
(Payload)
Xbee Radio
‘START’ to activate
telemetry
Data Read
Battery Voltage
Electromechanical
Deployment
Mechanism + Aerobraking structure
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• The Communications Subsystem Is a Transmitter Radio Used to transmit
telemetry Which Is the Data Collected in the CanSat.
• This system allow the CanSat to send the data back to the Ground Station that
can process the data to get relevant information.
• This is one of the most critical parts of the CanSat design that requires the
knowledge of the CanSat, the Ground System as well as the channel.
• The following are the selection criterion:
• Gain
• Range
• Frequency
• Price
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• The micro-controller is the main data handling unit for the CanSat.
• We are using an Arduino as the microcontroller unit for the CanSat.
• The selection is done considering the following outlined requirements:
Arduino Uno
Arduino Mega 2560
Arduino Nano
Processor Speed(MHz)
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Operating Voltage
5
5
5
Data Interface (D/A)
14/6
54/16
14/8
Size(cm x cm)
6.5x5.2
10.1x5.2
4.3x1.85
Flash Memory(kB)
32
128
32
Price(in USD)
25
65
50
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Factors affecting sensor selection for a CanSat system: (in priority order)
1)
2)
3)
4)
5)
According to the desired operation
Operating Frequency, accuracy, sensitivity, range of operation
Data interface required
Power Consumption
Weight, cost and dimensions
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