I miss driving.

Being away from home is hard and exciting at the same time. There are a few things I miss, and that includes household help, my bed, my friends, and my car. I don't have a car here in San Francisco so I only take the Bart when I need to go somewhere. I always try to look on the bright side though - that I will not be spending expensive gas and contributing pollution to the world.

Reading on ergonomics and automobile features made me remember the most useful tool in my car. When I ride other people's car I always look for this feature, and when I don't find it, I feel a bit unsafe driving it. This feature is the parking sensor (two of them) found in my rear bumper. Below is not my car, by the way.

This for me exemplifies the design principle of Feedback and perhaps, Constraint. Watching your hood area and front bumper while parking is fairly easy considering the fact that you have already gotten used to the size and limitations of your hood and front bumper. Not for me. I have grazed my front bumper a couple of times on walls and parking islands. And it has cost me pretty much in repair and repainting. My rear bumper though is clear and un-dented - because I have built-in sensors on it. This is most useful especially when parking or backing up. It is much harder for me to guess if the rear end of my car is near or far from a wall or another parked car, than guessing from the front end.

How does it work? Well I cannot explain the technical aspects of this sensor system (I apologize). In layman's terms though, as soon as you switch your gear to Reverse, the sensor is automatically activated. It provides immediate feedback and is synchronized with user action. If all is clear at the back, the sensor is quiet. But as soon as an object (wall, car, person, cone, or dog) is within 5 feet (or so) the sensor starts beeping inside the car. You can hear it very well so you know something is back there, even if you cannot see anything obstructive on your rearview or side mirror. Your foot automatically hits the break upon hearing the "feedback" of the sensor. If you were parking, that sound is enough to let you know that you can then park and leave. But if the parking area is a bit too crowded and you want to make the most out of your free space, you can continue to backup cautiously and slowly as the sensor continues to beep. The sensor will suddenly increase the speed of its beeping giving you the feedback that you are about 1 foot away from the object behind you, and that you should stop and not backup anymore. This shouldn't be done often though, since you wouldn't want to be too close to the car behind you - because chances are, he may not have a sensor.

New sensors may come also with displays inside the car (small tv screen or a display on your rearview mirror) so those who cannot hear, can see if the sensor is detecting something nearby. This adds Visibility and Mapping to the design as you see which particular sensor is affected, so you know which area you should avoid the most. It has to be easy to understand though, to avoid further confusion and complexity to the system. I believe I'd get confused trying to interpret the display above because I'd have to think about 4 separate sensors as opposed to just considering them as one whole sensor. I don't have a display in my car, but the beeping works fine for me. I just make sure my music isn't on too loud so I hear the beeping accurately. That's not much effort to do.

This feature definitely provides good constraint as it prevents you from hitting a car behind you (not necessarily have a car hit from you behind). Although it helps to prevent you from making your own mistakes, it cannot prevent other people from making their mistakes. But let's not go into that for now. (Although car manufacturers should try to come up with more ways to prevent cars from hitting each other accidentally - I've always thought about bubble wrappings but that would make a car look funny. Lol.) Moving on... parking sensors indeed provide good constraint factors when parking your car - but not entirely, of course. These sensors don't automatically stop your car from moving and hitting what's behind you. They merely warn you so you can avoid hitting anything. Well, it has kept my rear bumper safe, so I should probably install some on my front bumper too.

Sometimes though something weird happens to my parking sensor. In certain covered parking areas, my car starts beeping wildly on reverse even if there is completely nothing at the back. Sometimes I wonder if there's a ghost standing at the back or some electromagnetic field that is causing the beeping to go off like that. It has happened to my friend too on the same parking spaces. Haven't figured it out yet.

*Photos taken from Sstatee.com