Automotive Application - Opinion

[pmat]

Hi,
we are building an automotive project and i want your opinion in some issues:
1. GPS Module: We are interested in a module capable of generating output
not only for low speed environments (city traffic) but also for highway velocities.
We are specifically interested in having the position updated as often as
possible. Is a 10Hz update module sufficient?
2. Change direction lights: Is it possible to use some kind of sensor to detect
which one (light or left) of the change direction lights is active? We dont want
to interface with any of the car's equipment. We want our device to be autonomous.
Would an acoustic sensor be adequate?

Thnx,
Pavlos

 

[bkelly]

Hi,
...We are interested in a module capable of generating output
not only for low speed environments (city traffic) but also for highway velocities.
We are specifically interested in having the position updated as often as
possible. Is a 10Hz update module sufficient?
Pavlos

Are you not familiar with Garmin and other such products that are commonly available. Maybe you are not in a country where they are common. Highway speed is no trouble at all to GPS. I took my laptop GPS on a flight and it corrrectly showed the airplane speed and location. That was cool.

... Is it possible to use some kind of sensor to detect which one (light or left) of the change direction lights is active?

That is easy, provided you know some electronics and can make a voltage divider circuit. And know how to get to the car's wiring. Or maybe you can tap into a CAN circuit depending on the car model (I think, not positive). But do you really want to do that? It will be specific for each model of car. I have never had a need for that.

 

[jpanhalt]

2. Change direction lights: Is it possible to use some kind of sensor to detect
which one (light or left) of the change direction lights is active? We dont want
to interface with any of the car's equipment. We want our device to be autonomous.
Would an acoustic sensor be adequate?

It may vary by car, but it is very common to have only one flasher that serves both signal lights. Therefore the click would not help localize which light was flashing. Here is a link to a typical wiring circuit: HowStuffWorks "How Turn Signals Work"

You might consider an inductive sensor or Hall detector around the wiring to each light light to determine which one is flashing.

John

 

[pmat]

Thnx for the response,
I went through some sites and i saw that GPS modules targetting relatively slow moving objects like pedestrians or whatever go with a 1-2Hz update
devices. Now, GPS devices which are more suitable for high speed environment like racing etc. usually go with 10Hs update devices. The info about
your GPS operating correctly in the airplane is irrelevant, as we dont care whether the speed is calculated correctly (planes usually move with stable velocities), we care about the consistency
of the GPS module speed with respect to the actual speed of the object at a specific point in time. I have done some calculations and even the UART communication between
our microcontroller and the GPS module increases significantly the error, so we are thinking about making some assumptions about the speed
acceleration and time and somewhat correct the *current actual* speed as we see it. In any case, does anyone know whether for high speeds (up
to 300km/h) a 10Hz update module is sufficient? Could you propose a device which would be more suitable for our conditions??

With respect to the turn lights we would be interested in a device which preferably does not interface with car's parts. Our device is
a separate *independent* from the car box. Is there any way to figure out whether any of the two (at best case which one) is flashing?
Could we use an acoustic sensor??

 

[pk_volt]

Hmmm...

A little crazy of an idea, but I was thinking of sticking a photo sensor directly on the signal light on the car dash board But this wouldn't allow you to see the signal lights turn on and off anymore, unless you re-produce the light signal on top of the photo sensor with an LED

 

[pmat]

Crazy idea indeed!

So any ideas about the GPS issue i mentioned above???

 

[pk_volt]

Although I have used GPS in the past, but I'm no expert... BUT... I know that the GPS gives you a time stamp along with your velocity, and the time stamp should be VERY accurate.