Maestro A2100-B Manual do Utilizador descarregar pdf (Página 2)

frame.

1) Control Link: The transmission to control driving the

blimp and the camera movements is done by a 2.4Ghz RF

transceiver, this module is the NRF24L01+. The transmission

range of the nRF24L01+ sending out data at 256 kbps has a

range of 1000 meters. These range test are open area range

test, which means that there are no trees or buildings in the

way. Our hopes is for it to at least get 200-300 meters from

this transmitter, but if there are trees or buildings in our way

the range of the transmitter decreases dramatically and we

would still need to put in a failsafe in the blimp if we lose

transmission. The input voltage for the transceiver is 1.9 to

3.6 volts, and we will supply a 3.3 volt power line on the

microcontroller to the nRF24L01+. The current draw for the

transceiver module is 11.3mA at our optimal 0dBm output

power and for the receiver the maximum it will be is 13.3mA.

2) Camera Link: The transmitter and receiver combo for

the Camera System is a 5.8 GHz system in order not to

interfere with the 2.4 GHz frequency of the control trans-

mission. The combo that was purchased was a 5.8 GHz

STB Wireless Sharing Device AV Transmitter / Sender & IR

Remote Extender With 200M Transmitting Distance. The 200

meter distance was originally too short for what was needed

but after some experimenting 200 meters was decided that it

was perfect. The modules are slightly bulky and the antennas

are large and plastic but the overall weight of the transmitter

is very light and will be placed inside a wooden carrier. The

size was a little troubling but the weight of 72 grams with

the antenna included was decided to be good enough to work

with. The camera will be directly connected to the transmitter

via RCA cables. The transmitter then will transmit the picture

to the receiver which had to be connected to an analog to

digital convertor in order to produce a picture on the laptop.

B. Blimp Control System

The Blimp Control System handles all the servo controls

and the input from the sensor and GPS module on the Blimp

while it is in the air. This system uses the NRF24L01+

for long range data communication, for the directions in

movement from the GUI and thus the user.

1) Microcontroller: On the Printed Circuit Board of the

MASS is the Atmel Atmega328p. The Atmega328 has a RISC

architecture and has numerous possibilities when it comes

to controls. The microcontroller is used in the Arduino Uno

an entry level development board that is used by hobbyists

all over the world. The micro controller has a full 32kBytes

of programmable ﬂash memory. Although the amount of

memory needed was a guesstimate in the beginning of the

semester, the amount of memory in the Atmega328p was

more than enough. The package that was used was the PDIP

which has 28 pins. This packaging was used for the sole

purpose of needing to program the microcontroller, if need be,

on a breadboard. Other possible reasons were for the freedom

from surface mounting and easier testing. The ATmega328p

has serial communication capabilities.

The Atmel Atmega328 has ports for I2C, SPI and UART, all of

which will be used in our blimp to make it run fully. The SPI

port will be connected to the wireless transceiver which will

send in string commands from the user which in turn tell the

microcontroller to implement commands such as turning on

or off servo motors. The I2C port will be used for an inertial

measurement unit, or as it is called the IMU. Through the

various addresses, the data from the surface mount modules

will be sent to the master which is the microcontroller

in this case. This data will be used for direction of the

blimp (magnetometer), stability (gyroscope), and motion

(accelerometer). The UART port will be used for reading in

data strings from the on board GPS module. This data will be

used to orient the position of the blimp anywhere in the world.

2) Global Positioning System (GPS): We choose the 927-

A2100-B model by Maestro Wireless. The A2100-B model

is the ﬁrst model made by Maestro using CSR’s SiFRstarIV

chip on GPS modules. It is a fast, highly responsive GPS

that has accuracy down to -163 dBm. The GPS module that

is on the PBC of the MASS is the Time to First Fix GPS

module. It has 20 possible channels meaning, 20 possible

satellites to receive GPS coordinates from. This allows for

the most reliable position with the least amount of noise.

The module is a Surface mount device. The codes that will

be read from it are the GSA and GLL codes. GSA will ﬁnd

active satellites and GLL is for ﬁnding the longitude and

latitude of the module.

3) Inertial Measurement Unit (IMU): The IMU consist

of a Gyroscope, Accelerometer, and the Magnetometer.

The board that we are using is the Atmel AV 4018 which

designed as a daughter board for the Atmel AVR Xplain

line of development boards. Our plans are to incorporate

this board and grab data from it on our Atmel Atmega328p

Microcontroller. The IMU uses the I2C serial output for data

output on all three modules, from the IMU 3000 Gyroscope

we receive the degrees, from the Accelerometer we receive the

g’s of the x, y, and z directions, and from the Magnetometer

we receive the current heading in degrees (the compass for

our routing between GPS coordinates).

C. Camera System

The camera system will be placed just slightly towards

the front of the blimp while the motors will be in the front

and the gondola will be in the middle. The camera system

should have two ways of being moved. When on the autopilot

feature the IMU or more speciﬁcally the gyroscope should

sent data to the Atmega 328 microcontroller and the Atmega

would then account for the tilting in the blimp and move the

system accordingly. When on user controlled interface mode

the camera system can be controlled by using the left trigger

stick to pan up to 180 degrees or tilt180 degrees. The 180

degree limit worked well because too much tilting will just

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