Hello Everyone,

We recently moved and the new place has a bigger garage than before.  My wife now parks in the garage, something she’s never done before.  Her main problem is not knowing how far forward to pull the car in.  Instead of the traditional Tennis Ball hanging from a string I decided to take a Parallax approach to the problem at the risk of hurting Tennis Ball sales.

The Garage Parking Assistant makes it easy to pull in the garage by signaling you with a traffic-light style display of when to pull in (GREEN), slow down (YELLOW) and stop (RED).  If you pull too far in the Red LED blinks to let you know.  Although this type of project has been done before I wanted to take my own approach and simplify the code and hardware while making it easy to adjust/personalize for your own use.  By default all measurements are in inches, although you could easily use centimeters since that value is available as well.  The range of the PING))) sensor is split up into four zones labeled Zone1 through Zone4.  Please see the first attachment for a map of the zones.  The values for each zone are inches from the sensor/wall.

Zone1 is closest to the sensor/wall and indicates the area you don’t want to occupy.  When you are in this zone the Red LED will flash on/off to indicate you are too close.  In our garage this area is big since we want to be able to come around the front of the car with plenty of room.  The default setting for Zone1 is 36 inches (3 feet).

Zone2 is the area where you want the front of the car to stop in.  This will be between the Zone1 and Zone2 settings.  When you are in this zone the Red LED will be on solid telling you to stop since you are in the desired zone.  You don’t want to make this zone too small since you will need to stop within it without having to keep adjusting.  You also don’t want to make it too big.  The default setting is 46 inches.  When you set this you want to make sure this is as far back away from the wall as you want to be as well.  In our garage if we’re closer to the Zone2 mark the back of our car still has about 12 inches of clearance from the overhead door.

Zone3 is the area you set where you want to be prepared to stop.  When you are in this zone the Yellow LED will be on letting you know you are approaching the Red zone.  The default setting for this zone is 80 inches and works well for our garage and the speed that my wife enters it.  You will of course want to tune all of these values.

Zone4 is the area from where the PING))) sensor first detects the car until where you enter the Yellow zone.  When you are in this zone the Green LED will be on.  By default this value should be the maximum range detected by your PING))) when no car is in the garage.  This is the zone where you can pull in normally.

While not required, a laptop is a great help in getting everything where you want because while the code is running it is displaying the values it sees on the DEBUG screen and you can note these positions when setting your Zone constants.  You will definitely want to know what the maximum value your PING))) sensor reports when no car is in the garage and you’ll want to make sure that value is stable and set the Zone4 value to this number.

As in many previous projects this one was built on a Super Carrier Board.  This inexpensive project board is ideal for finished projects because it contains most of what the Board Of Education does, except that it is intended for soldering and runs the BASIC Stamp Module from the on-board regulator allowing a wider range of supply voltages.  The cases that the PING))) and Super Carrier Board were mounted in were just plastic prototyping enclosures I had in my parts cabinets.  You can refer to the Bill Of Materials for the sources of the ones I used although any enclosure which will fit these boards in will work.  Optionally you can mount both the Super Carrier Board and the PING))) right to the wall, although you may want to cut the Power LED trace to prevent it from giving you a false GO signal.

As you can see by the pictures attached I used 10 mm LEDs in this project since they’re much easier to see.  The schematic shows that there are 220 ohm current limiting resistors for the Green/Yellow LEDs while the Red has a 470 ohm resistor.  This is because the Red LED requires less current at the same light intensity.  So to make the LEDs uniform I used these values.  Different LEDs have different forward voltages and currents so you may need to adjust these values depending on the LEDs you use.  Often 220 ohm through 470 ohm resistors will work for most LEDs.  You may also notice I used 1/4 inch plastic spacers to keep the LEDs at the same height from the PCB.

If you have any questions on this project please feel free to post in this thread, PM or e-mail me.  Parallax can not provide phone support for this project.  Comments and suggestions are welcome.  Thanks everyone.

[Edit: Small Fix to code made for DEBUG messages]

Post Edited (Chris Savage (Parallax)) : 3/10/2007 12:38:25 AM GMT

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Post Edited (pwillard) : 6/23/2007 12:52:57 PM GMT

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