The aim of this project is to develop a 3D indoor
real-time positioning system used on fast moving objects like MAVs(micro air
vehicles). The positioning information can be demonstrated on an upper computer
in real time in an easy-to-read way. All the communication and data
transferring are accomplished wirelessly.
It’s part of our indoor quadrotor program. The whole
program was inspired by the MAV researches carried by MIT and UPenn.
Technologies
and tools involved in this project
Msp430, Altium Designer, Labview, Zigbee, Ultrasonic
generator and detector, CCS, GPS, 433 communication module.
My positioning method is to deploy a group of reference
nodes inside a certain space, and measure its distance to the moving node. Each
of them contains a microcontroller, a Zigbee wireless communication module and
sensors for distance measuring. With the extension of space, the number of node
increases, so each node sshould carry the traits of low cost, low power
consumption, and fast speed.
Each reference node grasps the signal from the moving
node, measures the distance between them, and transfers the distance
information to a central PC. I put the 3D position calculation work on the
central PC to utilize its advantage in speed over microcontrollers.
The reference and the moving node
Reference Node
MSP430 G2433 microcontroller. MSP430 serial, with its
reputation on ultralow power consumption and cost of less than 2 bucks.
Zigbee module. Long distance, capable of self-organizing,
with maximum of 65530 nodes in a wireless network.
Ultrasonic detector.
433 receiver. An off-the-shelf module, to compose the
distance measuring part. In pair with the transmitter.
Moving Node
MSP430 G2433.
Zigbee module.
Ultrasonic transmitter(top). Emit a 60 degree ultrasound sphere
so that detectors on different directions can receive the signal.
433 transmitter.
The moving node is designed to be light-weight. I
designed a PCB with Altium Designer to enclose all the components, make the
little node looks neat and compact, easy to be mounted on MAVs as well as other
moving robots and objects.
The PC controller
PC Interface
Zigbee with a serial to
USB board, the PC just need a USB port to communicate with the network.
User Interface
I wrote this User interface with Labview, and G-Language
provided by NI. It can stop and run the positioning process. The 3D coordinates
will be displayed in number. I kept the raw data from nodes on display for
inspect.
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