Hello!

I want to find the position of objects on my sensor field. I have uploaded the diagram of sensor field attached

In the figure S1-S8 are the laser sensor pointing into the field. While red and yellow are the balls



Case 1:

if there is only one ball, say red, sensor S3 and S5 will buzz. Hence we can locate the ball position on the field.


Case 2:

Now problem comes when there are two balls on the field. In this case they can be at 4 positions in the field and hence solution fails.

Is there any algorithm that can be used to remove the 2 redundant positions and find the actual position

Thanks

Attachments mesh.jpg 16.97 KB

Hello!

I want to find the position of objects on my sensor field. I have uploaded the diagram of sensor field attached

In the figure S1-S8 are the laser sensor pointing into the field. While red and yellow are the balls



Case 1:

if there is only one ball, say red, sensor S3 and S5 will buzz. Hence we can locate the ball position on the field.


Case 2:

Now problem comes when there are two balls on the field. In this case they can be at 4 positions in the field and hence solution fails.

Is there any algorithm that can be used to remove the 2 redundant positions and find the actual position

Thanks

Wow this problem takes me back to my old college days here in the UK, when I was on an electronics and computing course....ahh I remember the old traffic lights model we had to control using a bbc micro and machine code and all of the miniaturised industrial machinery and sensors we used to mess around with....Anyways, enough nostalgia...

Looks like you're in a bit of a catch 22 there. There's no obvious solution that I can see.... As you've said, when there are two balls on there, as far as the system is concerned there could potentially be four balls there.

In fact if you put four balls in the marked positions, the sensor array would be in exactly the same state as with the two balls, so how would you differentiate between those two states?? I don't think you can!

I think this configuration is really only going to be good for picking up a single object in the grid.

I assume you are using some kind of reflectors opposite each laser and then are just detecting if the beam has been broken...

Perhaps if the objects being detected in your field were reflective maybe you could measure the reflected beam intensity and thus calculate the relative distance of the objects from the lasers. That might allow the system to get a better idea of the objects position in the grid..

So using this method, with your two balls at positions s3,s5 and s1,s8:
Readings from s3 would allow the system to deduce that there was an object in front it, roughly in line with s5's position. Likewise, from s5 we'd be able to deduce that there was an object in its line of sight roughly in line with s3.
from s1 we'd deduce that there was an object roughly in line with s8, and from s8 we'd deduce that an object was in line with s1...Which would give you two unique positions.

But then there is the chance that different objects would reflect light in different ways and in differing amounts, so that could put paid to that theory, as the reflectivity of different materials would affect the reflected beam intensity and thus affect the calculation of the distance.....Bugger!

Also if you had 4 balls in your grid at the marked positions:
From s3 we'd be able to work out that something in its line of sight was in front of s5, from s5 we'd see something at s3, s8 would see something at s3 and s1 would see something at s5. But none of the sensors would detect the ball at s1,s8. So only three of the four balls would be detected.....Damn, that's me out of ideas!

One other alternative would be to configure 16 lasers directly above your grid pointing downwards (4X4), they'd be able to more effectively track the objects in your grid, making the original 8 lasers redundant. You could put up to 16 balls in your grid then and they'd all get detected. As soon as one of the beams is broken, you'll know there's something there!

Sorry about that, for all that brainstorming, it looks like I was no help whatsoever!

Jas.

Thanks for your reply and a bunch of ideas. Using 16 lasers pointing upwards is a definate solution but then it needs double the number of sensors. Secondly what if the ball is above none of sensors rather somewhere in middle of 4 sensors.

Hence we will have to stick to this the 8 laser configuration. Any other idea will be welcome :)

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