maths question
-
Your question is really unclear, are you trying to calculate d1? Regardless, if you have neither the positions nor the angles of the devices then you can't get an accurate calculation. Your best option would be to use which ever device gives you the shortest distance, as that will be the most accurate - but certainly cannot guarantee a correct result. Essentially to get the correct result you need a device pointed directly at the centre point. If they are not pointing directly at the centre point then you could probably compensate for this offset is your calculations, but you would need the angles and positions to be able to do so.
I need to calculate XY position in which the sensor finds the part. The problem is that the sensor is at an unknown position and angle (which will be very similar to the desired one but I need a really high precision (3 micrometers)). I only get from the sensor the distance from the sensor to the part.
-
I need to calculate XY position in which the sensor finds the part. The problem is that the sensor is at an unknown position and angle (which will be very similar to the desired one but I need a really high precision (3 micrometers)). I only get from the sensor the distance from the sensor to the part.
-
Like a beam that hits the surface of the circle and you have the distance without the angle?
"The only place where Success comes before Work is in the dictionary." Vidal Sassoon, 1928 - 2012
-
Hi all, I need help in a math issue: Let's say I have 3 measuring devices which give me a distance. Mechanically those 3 sensors are mounted more or less in the right position, but we can't be sure of the angle neither position the measuring devices are mounted. I have 3 Mastering parts (3 circumferences of a known radius) that I can mount into the machine at any moment and that I want to use to calibrate the system. The measuring error of the 3 measuring devices can be dismissed. this is a small diagram to represent the problem: https://i.stack.imgur.com/a2AyG.png[^] 2 known master circumferences give me a distance [d1] between circumferences (d1 = radius 1 - radius 2). For each circumference the sensor will give me a different measure m1 and m2. Given the difference between r1-r2 and m2-m1 could I find the angle in which the measuring device is mounted? Summarizing: 2 master circumferences mounted in the same center. 3 external measuring devices mounted completely unaligned with the center. I don't know the measuring devices position. The red lines in the drawing are the vector lines the measuring device measures would be placed into. The real measures (in this drawing) would be the distance from the sensor to the position where the red line crosses a circle. Any help will be welcome... Thank you all...
We have the distances m1 (between the measuring device and the outer circle), m2 (between the measuring device and the inner circle), r1, and r2 (the radii of the two circles). If the measuring device were pointed exactly at the common centre of the circles, then m1 - m2 == r1 - r2. If it is not pointing at the centre, the direction vector traces a chord on each of the circles. One chord is the intersections of the direction vector with the outer circle, and one chord is the intersections of the direction vector with the inner circle. The difference between the two chords is 2*(m1 - m2). If the measuring device is at a distance R and angle alpha from the centre of the circles, you should be able to calculate the lengths of the chords in terms of R, alpha, r1, and r2. Working backwards, you should get a formula for R and alpha in terms of m1, m2, r1, and r2.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.
-
Like a beam that hits the surface of the circle and you have the distance without the angle?
"The only place where Success comes before Work is in the dictionary." Vidal Sassoon, 1928 - 2012
Yes, in that case is a mechanical measuring device, but yes, the red line would represent a beam that measure the distance, but I don't know the incidence angle. Thank you for spending time on that, I'm sure my super explanations are not making it easy to understand it.
-
Joan M wrote:
I only get from the sensor the distance from the sensor to the part.
So just to be clear. Do you just get a single value (distance) from the sensor to the outer circle? Or do you get 2 values, one for outer circle and one for inner circle?
-
One for each circle. Thank you for spending time on this. And sorry for my bad explanations, it's difficult for me to describe this clearly in English...
Joan M wrote:
One for each circle.
Ok, that is a good start. We definitely need both. The other vital piece is: do you know the value of d1? (i.e do you know the radius/circumference of both the inner and outer circles?) It looks like Daniel is already suggesting what I am trying to get at too, however I just wanted to be sure you have all the information that he is trying to make use of.
-
Joan M wrote:
One for each circle.
Ok, that is a good start. We definitely need both. The other vital piece is: do you know the value of d1? (i.e do you know the radius/circumference of both the inner and outer circles?) It looks like Daniel is already suggesting what I am trying to get at too, however I just wanted to be sure you have all the information that he is trying to make use of.
-
Ok, so my trig is rusty so I will need to take some time to try and process the information. But from what I can see I think it should be possible to do with that data - but don't hold me to that just yet, this is not a specialist area for me by far! :-D
-
Ok, so my trig is rusty so I will need to take some time to try and process the information. But from what I can see I think it should be possible to do with that data - but don't hold me to that just yet, this is not a specialist area for me by far! :-D
-
Yes, in that case is a mechanical measuring device, but yes, the red line would represent a beam that measure the distance, but I don't know the incidence angle. Thank you for spending time on that, I'm sure my super explanations are not making it easy to understand it.
Some observations: 1. Replacing the circle (disk) with an other one will not change the distance the devices measure as long as the circles are on the same plain... 2. There is an option when one or more of the devices will not hit the circle's surface (infinite or error)... 3. There is a whole sphere for each point on the circle's surface that will return the same measurement...
"The only place where Success comes before Work is in the dictionary." Vidal Sassoon, 1928 - 2012
-
Some observations: 1. Replacing the circle (disk) with an other one will not change the distance the devices measure as long as the circles are on the same plain... 2. There is an option when one or more of the devices will not hit the circle's surface (infinite or error)... 3. There is a whole sphere for each point on the circle's surface that will return the same measurement...
"The only place where Success comes before Work is in the dictionary." Vidal Sassoon, 1928 - 2012
-
I need to calculate XY position in which the sensor finds the part. The problem is that the sensor is at an unknown position and angle (which will be very similar to the desired one but I need a really high precision (3 micrometers)). I only get from the sensor the distance from the sensor to the part.
-
Yes, yes and yes, but (and I'll write this in the OP) we consider all to be in the same plane. If it is not... I simply abandon all hope and start crying now...
Even the circle is on a fixed plain and the beams are always hit the surface, you can not know the position of the device as any of the devices can be at any point of a sphere and still return the same distance... If you would know the distance between the devices it would cut down the possible position to a circle (still a lot but less the a sphere)...
"The only place where Success comes before Work is in the dictionary." Vidal Sassoon, 1928 - 2012
-
We have the distances m1 (between the measuring device and the outer circle), m2 (between the measuring device and the inner circle), r1, and r2 (the radii of the two circles). If the measuring device were pointed exactly at the common centre of the circles, then m1 - m2 == r1 - r2. If it is not pointing at the centre, the direction vector traces a chord on each of the circles. One chord is the intersections of the direction vector with the outer circle, and one chord is the intersections of the direction vector with the inner circle. The difference between the two chords is 2*(m1 - m2). If the measuring device is at a distance R and angle alpha from the centre of the circles, you should be able to calculate the lengths of the chords in terms of R, alpha, r1, and r2. Working backwards, you should get a formula for R and alpha in terms of m1, m2, r1, and r2.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.
Which will place the device on a circle in best case... It still will not give you a XYZ position...
"The only place where Success comes before Work is in the dictionary." Vidal Sassoon, 1928 - 2012
-
XY I think you will never find. Assume you position the measurement unit exactly at 0° watching exactly the center. Do the same at any other angle (I mean adjust it exactly to the center).
It does not solve my Problem, but it answers my question
-
Sorry, having had some further time to think I don't see a solution. You need to have either the position of the sensor, or the angle of it (relative to the centre point). Without one of those you can't get the position where it intersects. Easiest way to see why: Take your diagram and rotate the whole thing 45 degrees. You will see that the expect output is clearly different, however you will still have the exact same input values. And logic states that the same input cannot produces different outputs - therefore the input data just isn't enough. Hope that makes sense. If you still don't want to give up, post a question on math.se[^], at least then you will get a much better technical explanation of why it can't be done that you can forward to the boss :) And if they somehow suss it out, please report back with the solution!
-
Hi all, I need help in a math issue: Let's say I have 3 measuring devices which give me a distance. Mechanically those 3 sensors are mounted more or less in the right position, but we can't be sure of the angle neither position the measuring devices are mounted. I have 3 Mastering parts (3 circumferences of a known radius) that I can mount into the machine at any moment and that I want to use to calibrate the system. The measuring error of the 3 measuring devices can be dismissed. this is a small diagram to represent the problem: https://i.stack.imgur.com/a2AyG.png[^] 2 known master circumferences give me a distance [d1] between circumferences (d1 = radius 1 - radius 2). For each circumference the sensor will give me a different measure m1 and m2. Given the difference between r1-r2 and m2-m1 could I find the angle in which the measuring device is mounted? Summarizing: 2 master circumferences mounted in the same center. 3 external measuring devices mounted completely unaligned with the center. I don't know the measuring devices position. The red lines in the drawing are the vector lines the measuring device measures would be placed into. The real measures (in this drawing) would be the distance from the sensor to the position where the red line crosses a circle. Any help will be welcome... Thank you all...
Consider a coordinate system with origin in the center of the mastering circle and one measuring device positioned at X0, Y0 (unknowns) sending a beam with a slope S (also unknown). The equation of the beam is: (1) y-Y0 = S*(x-X0) The intersection of this line with the mastering circle x2 + y2 = R12 can be found by solving (2) x2 + (s*(x-X0) + Y0)2 = R12 And then finding y from equation [1]. This will give you a formula with 3 unknowns (X0, Y0 and S) for the intersection point (Xi, Yi) Distance between the intersection point (Xi, Yi) and (X0, Y0) is given by: d12 = (Xi-X0)2 + (Yi-Y0)2 You need 3 such equations, from 3 mastering circles to solve the 3 unknowns. Note that solution for each sensor is independent of the other sensors. It's a bit early in the morning for me but the basic outline should work.
-
Hi all, I need help in a math issue: Let's say I have 3 measuring devices which give me a distance. Mechanically those 3 sensors are mounted more or less in the right position, but we can't be sure of the angle neither position the measuring devices are mounted. I have 3 Mastering parts (3 circumferences of a known radius) that I can mount into the machine at any moment and that I want to use to calibrate the system. The measuring error of the 3 measuring devices can be dismissed. this is a small diagram to represent the problem: https://i.stack.imgur.com/a2AyG.png[^] 2 known master circumferences give me a distance [d1] between circumferences (d1 = radius 1 - radius 2). For each circumference the sensor will give me a different measure m1 and m2. Given the difference between r1-r2 and m2-m1 could I find the angle in which the measuring device is mounted? Summarizing: 2 master circumferences mounted in the same center. 3 external measuring devices mounted completely unaligned with the center. I don't know the measuring devices position. The red lines in the drawing are the vector lines the measuring device measures would be placed into. The real measures (in this drawing) would be the distance from the sensor to the position where the red line crosses a circle. Any help will be welcome... Thank you all...
-
