Solution detection position autonomous car

Hi,
I'm new on this forum..
I would like to have somes helps.
I'm working on project to autonomous car in the University of Technology of Sydney.
I'm working on the part of detection and measure of position of the car.

The car is a Ford Courier Utility 4.0 V6 Crew GL.

I have somes ideas like reflective sensors with a disk black and white...
But there is several kind of sensors..( capacitance, eddy current, fiber optic, inductive, linear encoder, potentiometer, LVDT, photoelectric, magnetic, optical,...)
I hesitate about the choice of the sensors (magnetic, inductif, optical,...) and also about the target ( disk black/white, disk metalic with teeths,...)

I would like to have help or website which could to help me...

Thank you very much

Regards

What are the requirements for resolution? Can you go with GPS and use piezoelectric or radar as a backup system to prevent driving into something if you lose GPS lock?

If all you're looking for is distance moved forward, go with ferrous toothed ring and hall effect sensor. If the vehicle you're using has ABS, the ring and sensors are already installed.

-Rod

Thank you

Why not the possibility of effect hall...
In fact, we want to have a information of the position of the car.
So for you, the best possibilty is the a ring with teeth on metal with a effect Hall sensor??

Do you have other possibilties?? I would like find a lesson or a website showing the advantages and inconvenients of each sensor...
Can someboby help me??

regards

Again, knowing the requirements of your system will help suggest position sensors for your application.

Can you provide a scenario or "Concept of Operations" discussion? Will this vehicle need to perform an obstacle course autonomously? Will it be expected to perform collision avoidance? What type of speeds are you talking?

There are lots of possibilities, each with their own pros and cons depending on application.

Wikipedia actually has some pretty good write ups on Hall Effect sensors, optical encoders, rotary encoders, etc. That might be a good place to start. Your school's library probably has a plethora of information as well, and without a doubt you have access to professors that could help with suggestions.

-Rod

Yes that's sure
In fact I deal with just to design and establish a system which provide the position of the vehicle. It's just to have an information.
I don't deal with of detection of obsatcle.
The speed will not exceed 60 km/h.

I rode some article on wikipedia but I would like really all advantages and inconvenients but I will look for again...
Thank you

So do you just need to know position as far as how far the vehicle has traveled (relative position) or do you need to know precisely where the vehicle is at (absolute position)?

I don't want to keep asking for minute tidbits of information. Is there a specification somewhere on the Internet that explains what the competition is you are looking to compete in, or the requirements of what the autonomous vehicle must be capable of that we can review?

-Rod

There is an ABS system on this car, Ford courier utility.

So, We have thought maybe use the information of the BS system to have the position of the car.

But I would like to know the resolution of this system.
Do every ABS system have the same resolution?

I have an other questions
I would like to do a table about the hall effect sensor and eddy current sensor with the range in function the price.
Does website exist to find this kind of comparaison?

Thank you

Regards

Since you attend a technology school, sounds like measuring or calculating the resolution would be a better learning experience than getting the answer from a website. You probably have access to a handheld oscilloscope. Make a breakout box for the ABS system and connect the scope in parallel to one of the wheel speed sensors. Find a straight section of pavement and cound how many square wave pulses you get in some number of revolutions of the wheel, say 10 revolutions. Before starting, make sure all tires are inflated to the same pressure and record this pressure. It will be important to keep the pressure the same to maintain the same distance ratio during competition.

It's going to be hard to retrofit a different type of sensor for less money than free, which is what the already installed ABS system would cost you. You could argue in your white paper or report that you were looking for a system that would cost the least amount for a consumer to retrofit their vehicle with which is why you went the route of utilizing the common ABS system which already exists in many of the cars on the roads today.

-Rod

Thank you shorod

Can you give me more information about the test..
this kind of sensor doesn't require to an alimentation to work?
If not I can plug the scope directly on the sensor..

Since you attend a technology school, sounds like measuring or calculating the resolution would be a better learning experience than getting the answer from a website. You probably have access to a handheld oscilloscope. Make a breakout box for the ABS system and connect the scope in parallel to one of the wheel speed sensors. Find a straight section of pavement and cound how many square wave pulses you get in some number of revolutions of the wheel, say 10 revolutions. Before starting, make sure all tires are inflated to the same pressure and record this pressure. It will be important to keep the pressure the same to maintain the same distance ratio during competition.

It's going to be hard to retrofit a different type of sensor for less money than free, which is what the already installed ABS system would cost you. You could argue in your white paper or report that you were looking for a system that would cost the least amount for a consumer to retrofit their vehicle with which is why you went the route of utilizing the common ABS system which already exists in many of the cars on the roads today.

-Rod

I would suggest back probing the sensor with the scope to get the square wave rather than just unplugging the wheel speed sensor and measuring. This way the ABS will still work (even though at autonomous vehicle speeds ABS should not be a factor) and you'll have proper bias for the sensor.

As for the details on the test, somewhere you need to do some of the homework. I'm not getting a grade for designing an autonomous vehicle, and I'm not the one that's supposed to be learning as part of this project. There are lots of books and probably even websites in the "How it works" of ABS brakes. Calculating wheel/tire circumference and using it to determine distance travelled, then counting the number of pulses of the ABS sensor over that distance to determine what distance each pulse of the tone ring equates too is not a difficult calculation, especially for a student of a Technology school. You should also consider counting the number of teeth on the tone ring to verify what you see on the scope matches what the ring has for teeth. This is assuming there is no gear reduction between the tone ring and the wheel.

-Rod