What Are the Best Hardware Choices for a Wireless Parking System?

[Valdima]

Hi

I am in my final year of uni and for my project I am looking at doing it on a wireless sensor network for a car park application.

The thing that I am currently stuck on is that I am trying to define my specifications for the project, in particular the hardware specs.

My project is going to be modular and small scale, my design will monitor 6 bays and there will be all most real time updates to a web database.

I am struggling to decide on what kind of sensory will be needed, I mean there are a lot of choices and they all could work. Light, infra-red, ultra sonic. But i am aiming for low power consumption.

Also I am lost in regards to the communications, what type of wireless comms would be best, what device to choose, what speed.

And i will need to justify my choices for each piece of hardware.

I guess I am asking if anyone could help me choose or develop a criterion for hardware selection that would be great.

Has anyone designed a wireless sensor network? What was your reason for choosing the hardware you used?

 

[Valdima]

Any clarification needed let me know

 

[berkeman]

Hi

I am in my final year of uni and for my project I am looking at doing it on a wireless sensor network for a car park application.

The thing that I am currently stuck on is that I am trying to define my specifications for the project, in particular the hardware specs.

My project is going to be modular and small scale, my design will monitor 6 bays and there will be all most real time updates to a web database.

I am struggling to decide on what kind of sensory will be needed, I mean there are a lot of choices and they all could work. Light, infra-red, ultra sonic. But i am aiming for low power consumption.

Also I am lost in regards to the communications, what type of wireless comms would be best, what device to choose, what speed.

And i will need to justify my choices for each piece of hardware.

I guess I am asking if anyone could help me choose or develop a criterion for hardware selection that would be great.

Has anyone designed a wireless sensor network? What was your reason for choosing the hardware you used?

What is "a wireless sensor network for a car park application"? Does that mean something to help a car park itself? Or an RFID system to keep track of cars parked in a parking garage?

On your RF question -- what RF networking technologies have you read about so far? What are their strengths and weaknesses? This is your school project, so you need to show us your work and progress so far.

 

[Valdima]

Yeah i find that when i am searching for information i always get the self parking application.

no what my application is is a parking monitoring system to monitor the occupancy of a number of bays, yes like in a garage.

what i have in mind is a device that has a sensor that monitors a bay and this device also communicates wirelessly to other devices and then i will need some kind or database storage and a user interface to display the occupancy of the bays.

i am aware that this has been done before and i have found a number of IEEE papers about it but there really focussed on the management side of the project. i am interested in the hardware and the hardware selection

i have only just started the project and its taken me a little to really focus on a end product.

here is a quick diagram

[] [] [] [] [M]
| | | | |

[] is the sensor that communicates to the next sensor, i think its called ad hoc and then [M] is database. i am hoping to actually prototype it and test it on a small scale

i have not had any experience with wireless technology, big learning curve.

When you say 'RF networking technologies' do you mean like, wifi, blu tooth, infrared, ultrasonic?

i have never had to design anything like this so i am stuck in making the specifications like what you say the mode of communication.

 

[Valdima]

i have found this which has helped a little in understanding and just increasing my awareness of the options. its a quick relation of RF protocols. i am looking for low cost low power, because i also want to maybe power my module with solar panels

 

[pantaz]

An optical sensor may be the most power-efficient (for a non-contact method). Perhaps something like a LED/photo-transistor combo. Also, the sensors don't need to operate continuously. You can probably limit sensor on-time to once every 10 seconds or so.

Note: If your sensor only looks at the center of the parking space, it may miss a motorcycle parked near the side of the space.

 

[vk6kro]

There is another type you could consider. It is the inductive loop which you lay on the road and cars change the inductance of the loop when they drive over it.
http://www3.telus.net/chemelec/Projects/Loop-Detector/Loop-Detector.htm
See diagram link at the bottom of the article.
This is used to detect vehicles at traffic lights.

There is a lot of information on Google if you enter "inductive loop vehicle detector".

This would use a lot of components, though, if you need to duplicate it for each parking bay.

Another way is to set a counter to zero then count cars into a carpark and out of it. The difference is the number of cars parked.
If you don't care how long cars stay or exactly where they parked, this system works for big car parks.

Also consider the problems of tampering, vandalism and theft.
If evil children find a box with a relay in it and they can make the relay work (make a clicking sound) by waving their hands or a coin in front of it, they could add 100 or so extra cars to a parking spot before they get bored with it.
The inductive loop is fairly immune to this type of tampering.

 

[davenn]

In Sydney, Australia, there has been a number of occupancy parking systems installed in either new or existing multilevel carparks. They are all hard wired back to the monitoring computers and the sensors are all mounted directly of the centre of the parking bay.
As there is no reflector on the ground below the sensor, I suspect that ultrasonics rather than light is used.
These systems have been around for a few years now (5+) so you are kinda reinventing the wheel. ;). It is good being able to drive through the carparks and see displays that tell you how many spaces there are per level and also per any given row of park spaces.

Cheers
Dave

 

[Valdima]

thanks for all the advice,

yeah my application is for an open car park, where there are no boom gates. i imagined my university car park just open environment.

also i don't need to reinvent the wheel i need to show my problem solving skills, and time management skills et cetera.

good point about vandals

i guess i need to refine my question for now

ok the requirements for the Sensor are;

1. Low Power
2. Low Cost
3. Works at night
4. can detect all kinds of cars (not trucks or bikes)
5. safe from vandals
6. small
7. available

so i need to find a sensor that meets these;

so some types are;

• optical
• infrared
• laser
• ultrasonic
• inductive loop
• weight
• pneumatic tube

thanks ill have to research this a lot more, then ill need to do the same for the mode of communication

 

[davenn]

Ok
The extra info helped in what you are trying to achieve

The inductive loop is a good way to go, it's buried in the ground and that makes it vandal proof. I have had considerable experience with inductive loop systems, they are used in all the fast food drive through stores like KFC, maccas, etc etc.
Overall, if installed correctly, they are very reliable. You would bring each set of loop wires back to a central control box in the carpark whe the loop would connect to the oscillator board. The output from the oscillator boards could then be radio linked back to inside the building for monitoring.
The oscillator boards I delt with had several output modes to a LED on the osc board, depending on the loop operating ... eg

1... LED permanently on for vehicle present, permanently off for no vehicle present
2... LED flashing, 1pulse per sec if the loop was open circuit
3... LED doing double pulses if the oscillator was not working or off frequency
4... LED triple flash if the loop was short circuit

These info signals could also be sent back via the radio link to the control room computer
Also remember you will need to supply power to the control box in the carpark. You will need to consider if you supply AC mains voltage or a lower DC voltage depending on how far the control box is from the inside monitoring computer. That is a consideration regardless of the detection system you employ... Loop, IR, ultrasonics. Etc etc
They and the radio linking gear are all going to need power to operate

Cheers
Dave