Hi,
I'm a senior electrical engineer doing my final project. It's basically a smart wireless gate and parking system project. what I'm trying to do with my group mates is that we are trying to make an automated parking lot which opens the gate for authorized members of any kind of buildings whenever he/she is 5 to 10 meters close to the gate without even stopping and whenever the driver passes the gate, a 7-segment display will direct him to the area with the most free parking spots.
My main problem is in the wireless gate design, I've already ordered an arduino Uno and 433Mhz RF Transmitters and Receivers, and my main approach is to place a transmitter on each car and whenever it's in the range of the receiver the microcontroller checks if the driver is authorized through database matching, and if he's authorized the gate should open and show this member's information on the computer screen for security issues.
I have 2 main problems that I need help with :
If I have a transmitter and a receiver for each of the microcontroller's inputs and all of them are working on 433Mhz frequency, will they work normally if 2 or 3 of those are transmitting and receiving at the same time and place ? or should each of them work on a different frequency ?
The cheapest type of 433 MHz transmitters and receivers operate on a single frequency and simultaneous transmissions will interfere with each other.
What do you mean by "control the detection range"? Range depends on transmitter power, receiver sensitivity and antenna orientation and quality as well as distance.
I think you have more than two problems. Is your intention to have the automobile transmitter transmit continuously? In other words will the automobile go down the road and continue to transmit?
The other problem is how to identify a specific automobile. And finally what are you going to do with an unauthorized automobile at the gate and three more vehicles behind that one.
The issues of contention can be sorted out by ensuring that no two devices are transmitting simultaneously. There are plenty of schemes that could be used to implement that. The biggest problem is how you are going to limit the range to exactly the area you're interested in. Or, alternatively detect the location of the "authorised" car.
I'm with Paul on this one... Multiple potential issues.
The way RFID would do this is use a proximity sensor, pulse the ID module, and receive the returned digital code. Code would be "looked up" to authorize entrance. This is essentially combining two already utilized technologies:
proximity loop in street and
a smart card being touched/ swipped in a reader.
To be successful with RF only, you must merge these capabilities. If there is no authorization other than detection of an RF carrier you are at the mercy of propagation of the RF transmitter to RF receiver. Usually, such signals are omnidirectional but antenna design and placement can create a directional beam. Unfortunately, weather conditions may play havoc with your design. Also, vehicle mounting would need to be near identical and this may not be practical.
The cheap 433 transmitter and receiver pairs are natorious for being inconsistent with regard to precise power and antenna loading. Not much more than a cheap garage door opener.
An alternate approach would be a high intensity IR pulse from the gate area focused into the area where you wish to identify the vehicle. An IR receiver (like the 38K TV remote) would decode the request and respond with an ID code unique to that vehicle. Authentication would then be processed.
IR can be directed with simple optics into a conical beam. The receiver IR detector can be optically constructed to create a narrow reception angle. Powerful IR LEDs are easy to obtain. My understanding is that some jurisdictions use this technique for permitting emergency vehicles to circumvent traffic signals.
AdnanAlkhatib:
I have 2 main problems that I need help with :
If I have a transmitter and a receiver for each of the microcontroller's inputs and all of them are working on 433Mhz frequency, will they work normally if 2 or 3 of those are transmitting and receiving at the same time and place ? or should each of them work on a different frequency ?
Can I control the detection range ?
If two devices are sending all the time within the receiving range, the receiver will most likely only detect that device sending the strongest signal.
So you need sender and receiver with the gate and with the cars as well and a sending/receiving logic.
Programming logic for the gate:
Gate sends each second one request "Identify yourself" (let's say it takes 20ms)
Then the gate will try to receive any answers (lets say for 980ms)
If an answer with a valid identification code is received ==> open the gate
Next second, next cycle.
Programming logic for the cars:
The car is receiving all the time.
If the car receives the request "Identify yourself" it sends its ID as the reply code
As a fallback you better provide also RFID opening with an RFID ID chip besides of wireless transmission. Wireless can easily be sabotaged by sending on your frequency. So your system would not open any gate if a sabotage transmitter is sending on the frequency. Before you find out, the cars can be piled up in front of the gate if you have no fallback opening system.
Hi, a good final year project, just that it relies on drivers going to where they are told when they park.
If they don't then the most free areas will not be where you think.
Shade and undercover areas will go first no matter where you tell them to go, then closest to where THEY think they should be.
But I like the approach and open, instead of approach-stop-scan-open.
You will need to sense if someone has a different car for the day (no ID) but still try and enter on the fly, crash.
Tom.......
Have a look at how NASCAR and V8 Supercars and now GoCart electronic timing is carried out.
