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Creating a Speed Detection Limiter!!!

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jackr99

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Hi Everybody,

I am studying at Liverpool John Moores University and on my 3rd and final year. I am currently in need of help regarding my final year project.

I have decided to create a speed detection limiter that would allow speed to be controlled. the theory behind this is to use an emitter and reciever, the reciever in the car and the emitter placed at the start of every different speed zone eg 20mph, 30mph etc. each different speed zone will have a different frequency. when the car travels past/through that zone the emitter will send out there frequency to the reciever, which will cause the car to adjust to the specific speed within that speed zone.

i have to create a prototype of this theory!!!!!


I HAVE NO REAL IDEA WHERE TO START, dont no what circuit could be used etc


COULD ANYBODY PLEASE HELP ME!!!!!

THANKS JACKR99
 
I am not sure where you are going with this "emitter / receiver) terminology, however, you would likely start along these lines.

Use some form of sensor to detect speed. Rotational speed or whatever. This could result in a pulse train where the frequency is proportional to the speed. The frequency could be passed along to a Frequency to Voltage converter where now a voltage is proportional to speed. The voltage could be passed along to to a series of Window Comparator circuits. Something along those lines using discreet components. If you have experience using PICs and can program them, that opens more options.

As to starting somewhere you are either going to start with a sensor to pickup a signal proportional to speed or use an existing signal in the system proportional to speed.

Ron
 
this sounds alot more complicated. But I could use this for the theory part of the project, However how could i show this a a prototype ie not actually palcing it into a car. Could i create a circuit that would support this theory.

thanks for advice

jackr99
 
What I provided was merely an idea of one way to go about it. You use a speed sensor to get started. I don't care if you are monitoring automotive speed or shaft rotational speed. You mention zones as in for example 20 to 30 MPH (KmPH) which could be shaft speeds of for example 1,000 to 2,000 RPM (matters not). Then you mention once in a zone speed control which is where you lose me? Speed control, any speed control is generally a closed loop system.

Ron
 
Yes I understand the theory behind the rotational speed etc. What I ment (where I lost you) is when the car travels from one speed zone to another ( from a 30mph road to a 20mph road) an emitter will be place at the beginning of the changing zones, when the car passes through the zone the car (receiver) is then contacted by this emitter through frequency to Lower or higher the speed (in this Case lower).

All I want to know is how I could prove this theory using a prototype eg creating a circuit etc as i have no access to actually try my theory out in an actual car.

Jack
 
This is something i have pondered for years now and still have not found a feasible solution for.
I dubbed it "intelligent road signs"

What the OP means is to have a transmitter on each speed sign, on the road side and a receiver in the car, as the car passes the road sign, the zone speed is transmitted to the car.
With a method of then limiting the car speed to a max of the speed zone.

I personally would not go down the car speed limiting route, but would use a spoken warning follower by a over speed alarm, more so like current GPS systems use for direction instructions.

As i said i have pondered this idea for years and keep finding bugs in every method i ventured into.

Like how do you keep the transmission narrow and still cover 4 lanes of traffic, what happens when a truck passes between you and the transmitter, often there is 2 different speeds on opposite sides of the road so how do you stop data collisions, in the case of a transmitter failure who is responsible.

The simple answer is better logging of speed zones for use with GPS systems (as many people and new cars have them) then no need for all the extra junk.

This wont happen as it will reduce revenue, and the police wont have a drum to beat over road safety verses revenue. (why fix a problem if it is going to cost billions a year in lost revenue)

My current GPS has a form of speed warning but find the data is often so wrong it drives you insane and can not be trusted.

Pete.
 
Thank you SABorn, I finally understand. I kept having everything together or simply put, didn't get it. :)

I agree, it won't be simple for the reasons you mentioned. There are other reasons I would think also like accident avoidance maybe?

Ron
 
So from understanding, do you think think that I should forget the limiter and just try to create a speed warning voice eg "slow down risk of accident" or something etc. How would I use the gps for this.

Thanks pete

Jack
 
Most new cars here have a speed alert built in and you set the speed manually and it chimes when you exceed the pre set speed.

What i had considered building for myself was a speed alert that worked off GPS so i could take it from vehicle to vehicle without the need for sensor wiring.

I have not built this but will share my thoughts.
GPS pre built modules are rather cheap (look on ebay)
Interface the GPS with a micro controller (not too hard) and check each coordinate reading against the next over time to determine the speed of travel.
Either use a digital voice chip or a simple piezo to indicate a breach of speed.

Allow the user to enter a speed limit, also allow a set button to permit the user to log a set of coordinates and the set speed to eeprom at any point, so if you were travelling the same route on different occasions the system would detect the location and automatically adjust the speed limit to suit.
You would also need to add a warning for loss of GPS signal so you knew there was no speed monitoring in place.

The easy way would be to use a system similar to cruise control, where you accelerate or decelerate to a given speed and press a set button recording that speed and location. it cant get much simpler than that.
Given 12 months of regular use you would have logged almost every regular route you travel.

I have not seen this system in current GPS navigation systems and feel it could be easy done to allow user set information to be retained.

We often breach the speed limits unknowingly on regular travelled roads, that a simple user entry could solve.

Pete.
 
Hi SABorn,

I have decided to take up your idea and try to get it to work. As I stated previous this is for my Final Year project in University, so obviously i cannot implement and change a REAL ECU within an EMS. Therefore to show the theoury behind the ECU's job i will create a flow chart. However I am going to buy a pre biult GPS to try and implement it to allow roads to be recognised with the lawful speed limit (on that road). I have searched for prebuilt GPS but cannot find it, i have looked on ebay etc.

Have you any idea as to where i can get my hands on one.
Can you get back to me ASAP thanks

Jackr99
 
I have often thought of the same idea only using the same technology that is used for GPS units. A GPS knows what street or highway you are on, it knows which direction you are traveling, it knows how fast your are traveling. All you have to do is to make a program that knows the speed limit of each street and highway and combine it with data that is already available then make and sell GPS speed controllers. The unit will tell the driver the speed limit even if it is not posted on signs. If the driver goes over the speed limit the unit can be set to BEEP or FLASH etc. The hard part will be to update the GPS units when a cities all over the USA change the speed limit. That information could be sent to the GPS unit the same way Satellite TV companies send information to every receiver box on TVs all over the country so it updates automatically. Now days every thing revolves around $$$ so I can see people having to subscribe to a yearly update service for $20 per year. If you don't pay $20 fee for the yearly updates then you run the risk of driving the wrong speed and getting a traffic ticket. How much is a traffic ticket? In South Carolina a traffic ticket on the interstate will cost you about $780 this includes all sorts of crap, traffic school, tests, and I don't remember what else. I use my cruise control every place I drive including in town it keeps me from accidently driving too fast.
 
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Hi jackr99,

today's cars are normally equipped with ABS (anti blocking system) which monitor individual wheel rotation to apply brakes according to road conditions.

The ABS sensors could be used to determine car speed.

I do not suggest to adapt speed automatically since the traffic situation is unknown and might be fatal if emergency braking is necessary while the automatic throttle control dictates 20mph.

Driving through Denmark you'll find lots of speed indicators based on radar. They tell you the exact speed you're driving. If you miss slowing down you'll get a new photo of yourself sitting in the car - very expensive. :)

Every car driver is responsible for his actions and a speeding ticket here and there will be good for the community cash. :D

Just an over speed warning should suffice.

I once was asked to develop a system which I called "AGDS" (Anti Ghost Driver System) to be used for highways to prevent entry on the wrong lane.

My first suggestion was using IR detectors along the entries and exits with automatic engine shutdown if a highway was entered or left the wrong way.

The suggestion was appreciated but much too expensive to build and maintain - including car modifications.

My second suggestion was accepted. It was nothing but a mechanical solution puncturing all tires going the wrong way. :D

Boncuk
 
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