wireless sensor network for school project

My partner and I are trying to develop a wireless sensor network inside a vehicle. We have been looking at various kinds of sensors and right now we are considering having an accelerometer and a temperature sensor. From looking around at various boards, we have decided that it would be best to use xbee modules and arduino, but we are far from experts. If anyone has suggestions for products to consider or some insight into wireless sensor networks we would love to hear from you. Thanks

How many devices do you want to connect?

Arduino is easy to use and software development is easy. But most applications use one Arduino board and connect different sensors and LEDs to it. And most projects only communicate with a PC. So for reading sensor values, the Arduino is a great choice.

For connecting multiple Arduinos (and this is what you will do in a wireless sensor network) you need a network communication protocol. You could use I2C or SPI or use Ethernet shields... But I don't know a wireless sensor network that uses Arduinos.

If you want to concentrate on reading out sensor values then the Arduino is a great choice. If the distributed computing aspect is more important you will choose a system that runs tinyOS.

For a school project, the wireless part would be the second step I guess. A wired (yes, using wires) sensor network is a good start and then the wires can be replaced by "virtual wires" like bluetooth or xbee. Wireless adds a lot of complexity to the sensor network, especially if you want to use wireless lan.

A wired sensor network would work too I think, but the sensors will be in different parts of the car so I’m not sure if the wires would interfere with any other parts of the car (other people in our class are working on different parts of the car too) We sent a request to our teacher to buy these items, but I don’t know if we can use them:

SEN-09072 Waterproof Potentiometer
SEN-00245 One Wire Digital Temperature Sensor
COM-00853 Accelerometer - 2 Axis - ADXL202 +/-2g
COM-08128 Barometric Pressure Sensor MEMs
SEN-08925 SCP1000 Gasket

from sparkfun.com
I think for our project we need the sensor values and data more than the wireless, so if wired works that would be great.

What steps should we take to get started on a wired sensor network? Thanks

I would start with 2 Arduino boards.
Connect some sensors to one board and other sensors to the other board, just in the way you need them in your car.
Then you can use the Serial.print() function to send data from one Arduino to the other. This means you don’t have a real network but two directly connected devices (point-to-point). But it is a good start, because

  • it is a lot of work to read and interpret the sensor data
  • communication between to devices is the easiest use case. More devices increase complexity
  • many radio units can “emulate” a serial connection, so instead of the serial cable you connect a radio device.

instead of the serial communication you could also consider the EthernetShield: http://arduino.cc/en/Main/ArduinoEthernetShield
and connecting this to a wlan router makes your Arduinos wireless without any change in the code.

-I think your 2 Arduino board idea would work, we will probably start with that but how easy would it be if we decided to add another Arduino? -How hard would it be to interpret/read the sensor data with the two Arduinos, and how would we actually do that? -Is there any tutorial or guide you could refer us to so we can learn how to actually assemble everything? -How would the data on the 2 Arduino boards get back to the computer, where we want to receive the data?

I think for now we'll go with the wired sensor network, our teacher was actually recommending that to us.

Sorry if the questions are very elementary, we are pretty much lost...

First you have to understand the Arduino I guess. Start here

Start with the Blink example, then don’t miss the Analog Input example because many sensors give you analog values. And then in your case the ADXL3xx can be helpful.

and then look here for more inspiration:
http://www.arduino.cc/playground/

Try these examples with the Arduino board before you think about a sensor network. Once you know how to read your different sensors and how to interpret the values you should take the next step.

The next step would be: think about the overall structure. How many sensors should be where?
And to your question about the PC communication: this is the easiest part because you can connect one Arduino to the PC.

The XBees have a uC, A/D and digital IO. Some wireless networking and simple
control can be done using just the XBees. Check the XBee datasheet.
If you are going to want to log data or do a control system you will want a uC.

I have been making a board called the ZB1 that combines an Atmega168 (with
the Arduino bootloader) and an XBee. (see http://tinyurl.com/5rfmrz).
I will be adding a sensor interface board and a signal conditioning tutorial very
soon.

(* jcl *)

bohne: Would we need three Arduinos if we want two in the car and one connected to the computer? Or would we not be able to have streaming information going to the computer?

jluciani:I think this is what we first were thinking of trying but we didn’t really understand any of it…

Check out O'Reilly's "Making Things Talk" book.

If you can find an example in the book that is close to what you want to you will be up and running very quickly.

(* jcl *)

yes, You can use three Arduinos if you want. But there are many possibilities. If you can master two Arduinos then it will be easy to handle three Arduinos and four...

I also recommend this book, you will find many answers to your questions there. It will also introduce the Xbee and USB communication...

According this thread, wifi shield will be availalbe next month, not sure about the price though (50-70usd?) -

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1235716581

it will work in both infrastructure and adhoc mode...

If we wanted 2 sensors in the car to communicate wirelessly to the computer, would we need 2 Xbees and 3 Arduinos?

This could be done with just the XBees. One XBee connected to the sensors. The other to the PC with a USB cable.

(* jcl *)

You can connect simple sensors to the XBee. If you don't need to pre-process the sensor readings then this might be sufficient.

But I would start with an Arduino, learn how this physical computing stuff works and then take the next step and have a look at the XBee modules. Did you get an Arduino yet?

We just recently recieved the Arduino, and we've been trying out some of the examples in the tutorial. Where would we be able to buy some simple sensors, and how would they work with the Xbee?

Sorry for double posting, but is there anyone who could offer a little more information about the simple sensors and Xbees? Right now we're still confused if we are just using Arduinos, just using Xbees and simple sensors, or using both Arduino and Xbee. We have an Arduino and just ordered a DS1620 Digital Thermeter and Thermostat. We are about to submit a second order form to our teacher, but again, we're not sure what direction we're headed.

hello I am a a computer student at university.I want to work on Wsn for my engineering Project.can anyone suggest me a good subject on it. thx.

You can use it for a heck of a lot of things, what are you interested in? If the project is something you are interested in then you will find it much more fun to do.

Mowcius

thx for your reply I am interested in network and communication,but not in very low layer,like physical.I found Data Fusion interesting too, but I want to be more detail in the topic.I know just some generals and its not suitable for the title of a project.can you help me with a topic that is interesting and practical.maybe I could Paper it.

check www.adafruit.com www.sparkfun.com www.nkcelectronics.com you can get a sensor kit for the arduino tutorial handbook