As I said in another post, this project could really mean the difference between surviving (economically) or not, so IN ADVANCE, a really BIG THANK YOU for any and all input to assist. My previous trials with various Picaxe circuits had to lead here inevitably.....
The Chook-House controller is nearing final completion and will be tested under real bad (HOSTILE) conditions soon. I will report on that to this forum.
Now for this distance meaurement project:
The idea is to measure vehicle wheel alignment through a "drive over" platform mechanism. Slow speed drive over a "floating" platform with the wheel/s on one side. The other side's wheels will act as the "anchor" thus forcing any displacement onto the floating plate. The movement/displacement could therefore be either positive(outward) or negative(inward). With the right sensor, even very small displacement can be measured and interpreted, possibly as degrees or as x_mm over 3 meter distance etc. One would want to measure sub-millimeter movement to be as precise as possible and also be able to repeat these readings and hence be accurate to within tolerances of measurement.
I have asked already in the thread regarding the sonic measurement and that developed into BB's light/shadow measurement. That has a LOT of promise and I will one day look at that in earnest again. Since then, "logic" (possible ?? ) has led me down the path of good quality digital Vernier caliper devices such as those from Starret/Mitutoyo and Fowler_Sylvac as well as HeidenHain. Almost all of these are capable (claimed) of repeat accuracy of 20 micron and resolutions of 10 micron. For this project, 10 micron resolution is excellent and repeatability to within 20 micron is really good. So I thought to use these devices as most of them already have the built-in communications output, either via RS232 (Fowler 7bit data-2 stop bits) or Mitutoyo's proprietory type "SPC". In addition there are stand-alone Inductive sensors capable of similar resolution and accuracy with Analogue output (this I understand well and therefore like....) BUT, they seem to be virtually unobtainable in South Africa..... (any volunteer prospective suppliers on the forum ????)
Some specifications:
1. It seems one will have to allow for a minimum displacement of 20mm from center_Zero_point = 40mm total distance.
2. This displacement will occur with the wheel running over a +-300mm long floating plate.
3. Slow drive over, 3Km/H = 0.8m/sec = +- 0.25sec measuring period
4. Get as many readings as possible during the drive over in order to form a "graph" of Rate of Displacement = severity of mis-alignment.
5. Floating plate mounted on 4 x commercial Load Cells (also floating and already mechanically sorted out), to also get weight on wheel reading.
Why do this:
1. To provide an Auditing device of alignment done (sometimes not done correctly but paid for...)
2. To keep an eye on alignment and predict suspension etc. wear rates....(S.A. roads are getting notorious...)
3. To keep me economically alive.......... My previous sponsorship has now ended, but this is viable here for me...
4. This will result in the sale of a few more Picaxe 28x1's or 28x2's to "make up" for effort from Rev-Ed and this forum.
I will post some datasheets from various Verniers or Displacement sensors etc as I get them....
Thanks for reading, hopefully I can complete this within a reasonably short time.
The Chook-House controller is nearing final completion and will be tested under real bad (HOSTILE) conditions soon. I will report on that to this forum.
Now for this distance meaurement project:
The idea is to measure vehicle wheel alignment through a "drive over" platform mechanism. Slow speed drive over a "floating" platform with the wheel/s on one side. The other side's wheels will act as the "anchor" thus forcing any displacement onto the floating plate. The movement/displacement could therefore be either positive(outward) or negative(inward). With the right sensor, even very small displacement can be measured and interpreted, possibly as degrees or as x_mm over 3 meter distance etc. One would want to measure sub-millimeter movement to be as precise as possible and also be able to repeat these readings and hence be accurate to within tolerances of measurement.
I have asked already in the thread regarding the sonic measurement and that developed into BB's light/shadow measurement. That has a LOT of promise and I will one day look at that in earnest again. Since then, "logic" (possible ?? ) has led me down the path of good quality digital Vernier caliper devices such as those from Starret/Mitutoyo and Fowler_Sylvac as well as HeidenHain. Almost all of these are capable (claimed) of repeat accuracy of 20 micron and resolutions of 10 micron. For this project, 10 micron resolution is excellent and repeatability to within 20 micron is really good. So I thought to use these devices as most of them already have the built-in communications output, either via RS232 (Fowler 7bit data-2 stop bits) or Mitutoyo's proprietory type "SPC". In addition there are stand-alone Inductive sensors capable of similar resolution and accuracy with Analogue output (this I understand well and therefore like....) BUT, they seem to be virtually unobtainable in South Africa..... (any volunteer prospective suppliers on the forum ????)
Some specifications:
1. It seems one will have to allow for a minimum displacement of 20mm from center_Zero_point = 40mm total distance.
2. This displacement will occur with the wheel running over a +-300mm long floating plate.
3. Slow drive over, 3Km/H = 0.8m/sec = +- 0.25sec measuring period
4. Get as many readings as possible during the drive over in order to form a "graph" of Rate of Displacement = severity of mis-alignment.
5. Floating plate mounted on 4 x commercial Load Cells (also floating and already mechanically sorted out), to also get weight on wheel reading.
Why do this:
1. To provide an Auditing device of alignment done (sometimes not done correctly but paid for...)
2. To keep an eye on alignment and predict suspension etc. wear rates....(S.A. roads are getting notorious...)
3. To keep me economically alive.......... My previous sponsorship has now ended, but this is viable here for me...
4. This will result in the sale of a few more Picaxe 28x1's or 28x2's to "make up" for effort from Rev-Ed and this forum.
I will post some datasheets from various Verniers or Displacement sensors etc as I get them....
Thanks for reading, hopefully I can complete this within a reasonably short time.