Car Monitoring project

[Haidy]

Hello all

im an Egyptian engineering student
my project is monitoring every thing in car:
speed,distance to surrounding obstacles,temperature,oil leve& pressure,battery stautus, door & light status,......

well, i searched alot for sensors ,measuring speed&distance to surrounding obstacles specialy ,but i found nothing except ultrasonic sensors

now, i mentioned that im Egyptian coz these kinds of sensors are expensive here
too expensive for a student to buy

i dont know what to do
can any one tell me what sensors to use or what way to measure speed and distance to surroundings but without paying much money?????
even i the accuracy is not too good

by the way, i found sth called "purpose built potentiometer" for measuring large scale distance
but this is the only piece of information i found about it, nothing more!!!!

i wish u help me plz, or i'll have to change the whole project, and im running out of time!!!!!!!!

thanx alot

waiting ur replies
byeeee

 

[Sceadwian]

You can retrieve a huge amount of information interfacing to the cars on board diagnostics. Ultrasonics are going to be the only practical method that I can think of to detect nearby objects but an array to do that in 360 degrees is going to be a real challenge to design.

 

[Haidy]

Re:

Thanx alot sir

well,
ithought of something else
to directly measure the speed of the car
infact it's the speed that's required
so i thought of calculating distance and dividing it by time

now i changed my mind, im thinking of measuring speed directly

can u help me in measuring speed?
i'll measure N(of the wheel) in rpm, then omega then linear velocity V.
i have some ideas like:
-encoder, but it will be difficult for my car model
-tachogenerator, infact im not familiar with it

plz give me any ideas,

but still, distance to surroundings will need necessarily ultrasonic?

plz tell me
thanx alot

bye

 

[ClydeCrashKop]

I have been working on a tachometer lately. For low frequencies, someone recommended reading time between pulses. I tried that and found that as the frequency increases, the time between pulses shortens EXPONENTIALLY. I didn’t EVEN want to sort that out in PIC asm with RISC.
Anyway, you gave me an idea. A hall effect sensor close to the differential ring gear should give you 20 or more pulses per axle revolution. Has anyone done that?

 

[Nigel Goodwin]

I have been working on a tachometer lately. For low frequencies, someone recommended reading time between pulses. I tried that and found that as the frequency increases, the time between pulses shortens EXPONENTIALLY. I didn’t EVEN want to sort that out in PIC asm with RISC.

I suggest you try again, the relationship between frequency and wavelength is a simple linear one.

 

[ClydeCrashKop]

That is what I expected but not what I got. I will scan a graph of it.

 

[Nigel Goodwin]

That is what I expected but not what I got. I will scan a graph of it.

"Ye canna change the laws of physics, Jim!"

 

[ClydeCrashKop]

Nigel, this is from your joystick tutorial but using timer1 and no cap discharge.

ReadX ;clrf Timer_H ;clear timer hi byte
bsf STATUS, RP0 ;select bank 1
bsf JOY_TRIS, PotX ;make PotX an input
bcf STATUS, RP0 ;select bank 0
clrf TMR1H
clrf TMR1L
btfss JOY_PORT, PotX ;These two to make sure it starts at a full cycle
goto $-1 ;loop until input high
btfsc JOY_PORT, PotX
goto $-1 ;loop until input low
bsf T1CON ,TMR1ON ;start timer
btfss JOY_PORT, PotX
goto $-1 ;loop until input high
btfsc JOY_PORT, PotX
goto $-1 ;loop until input low
bcf T1CON ,TMR1ON ;stop timer
movf TMR1L, W
movwf LoX ;and read immediately
movf TMR1H, W
movwf HiX
retlw 0x00

 

[ClydeCrashKop]

Sorry, we kind of hijacked Haidy’s topic.
Back to car monitoring.