Help: Solution for Detecting the No of persons sitting on a seat

250 is the initial weight of motor cycle

Yes that wasn't the figure I was referring to.

Its very hard for the scooter to measure itself, but the initial scooter weight is not a factor anyway...

This shows how this won't work.

Scenario1       Person A weighs 40kg, person B weighs 40kg, luggage weighs 10kg. Luggage is picked up and carried after A and B are seated.

Scenario 2      Person A weighs 40kg, person B weighs 40kg, person C weighs 10kg. They get on last.

Scenario 3      Person A weighs 50kg, person B weighs 30kg, person C is being carried by person B and weighs 20kg. and gets on at the same time.

Placing a load sensor in the seat only works if they sit on the seat, and the spring rates are non linear, so unless you modify the spring mounts (front and rear) you're likely to have to calibrate the sensor.

Once you do that you have a way to 'bypass' it.

The reality with any of these methods is there is a way to overcome them and humans tend to find the way.

Now the other question.

What do you do in an emergency when it would be desirable to be able to load the scooter with 4 (or more) people as the roads are damaged so other vehicles can't get through, and you need to get them to emergency care.?

Mark

     "The reality with any of these methods is there is a way to overcome them and humans tend to find the way."

Mark, if you think this way you will never find a solution. You are also making the problem bigger than it is. Scenario 1, two people and luggage should also be too much for a motorcycle. Scenario 2 works fine.

It is possible to limit the speed instead of a blocking situation. Or any other annoying adjustment.

Finally It seems that you have a ride on a cycle of some kind that you don't want more than one person on. Could you put a row of temp,  pressure, light, etc. on the seat or frame to get a gradient or peak value of the sensors. There should be a peak for each of the passengers.

Bill

First things First:: Please dont worry about you  doing my homework i have came to this forum only after getting stalled. Moreover iam a Research Student, School times have passed things arent proving that lucky now.

1, I tried to use Weight Sensors But no relief the human weights vary largely from 40kg to 130 kg/person so i cant have a reference weight. Moreover if i set a maximum limit of 150 kg for average for 2 persons the same gets violated by  a single person carrying 2 kids.

2.I thought of using sensors on Foot rest pedals there to some times while riding off limits the 3rd person leaves his legs hanging as there is no Foot rest pedal to rest on as the bike is designed for 2 only.

3. I tried using bubble switched but got limited as each switch took a i/o pin. Then i tried to use the matrix type press detection as we use in Keyboard in that the problem encountered was when a switch gets pressed the port becomes High and remains high making the entire row and column in high state while as in keyboard the key bounces back.<<New Ideas&techniques are Welcomed on this>>

4. Now trying to use the principle of transformer(emf). I will put a layer of conductive solid surface which will be having a definite charge as base  and on top  i will put strips of another conductive element they will be separated by a dielectric between them. As the person sits the strip will be sandwiched resulting in more emf on the wire.. so i will put many wires and detect the change in the seat load and by that i can get pressure points too and detect the persons seated..<suggestions welcomed>

5. The aim of the project is to be a cheap yet effective solution, i could use a dozen high tech sensors and controllers but lets not forget it to see it from market perspective.

APPRECIATED!!

I think you should have disclosed your work thus far initially, but that's just my opinion; take it as such.

I think I have to agree with Victor, the camera and image processing will be the best result. You might even need two cameras, but the hard part will be where to mount the cameras. I don't have experience in this area, but I've seen what cameras and image processing can do. That's my two cents.

Eeschan from what I've seen when the Bikes are over loaded they have the whole family and often some livestock attached.

As you can imagine not all are on the seat so maybe that's not the place for the sensor have you considered on the rear/Front suspension.

In fact use the deformation of the suspension as the sensor! Also measure the number of times the weight goes up by a reasonable amount not the actual amount

BTW So far around Delhi the record I found was 7 people  and shopping on a 50cc Motorbike!

Michel this was my first post in Element14 i didnt even know that i would get a response.  I know that Image Processing would do but in Two wheeler i don't have a definite place to mount making it unsuitable.

Sensing the suspensions may not be a good idea because this idea is the same as the weight sensors. I mean to say the same limitations.

I think the weight one could still work. It's not the maximum you need to worry about. If you place one long strip of strain gauges down the center of the seat you could look at the strain distribution along the seat. Two strain peaks for two people, three peaks for three people, etc...