Seen from here: to enhance professional education, motivate students and open your eyes.dirk pitt wrote:what are the [...] last comments of this post for?
Well said ;)dirk pitt wrote:refrain from relaunching the controversy without stopping
electric horse-drawn tow !!!
Obamot wrote:Seen from here: to enhance professional education, motivate students and open your eyes.dirk pitt wrote:what are the [...] last comments of this post for?Well said ;)dirk pitt wrote:refrain from relaunching the controversy without stopping
He still edited his message which said this:
Well seen.
dirk pitt wrote:
what are the [...] last comments of this post for?
Mine is very clear, to open your eyes and not to demotivate the students.
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Stepping behind sometimes can strengthen friendship.
Criticism is good if added to some compliments.
Alain
Criticism is good if added to some compliments.
Alain
Alain G wrote:In short, what you used is what we use in an electronic scale and it is a high precision sensor which requires complicated electronics to convert a simple charge!
load cells = force sensor
It’s probably a strain gauge, it is neither complicated nor expensive, it is what we find in scales and electronic scales. The trick is not worth more than a euro, but the difficulty (which makes the price of the complete sensor) is in the mechanical assembly on a part which must deform "just as it should" according to the applied force. There is no need for precision to 0.2 grams here as in a scale.
The electronics are a wheatstone bridge, an op-amp, a microcontroller and a few sensors (brakes, etc.), very complicated indeed, there's at least 10 € ... lol.
All the intelligence is in the mechanical assembly and especially the servo algorithm, on which I would like to have details, because it must be very interesting. Is the gadzar report online?
It could be transposed to an electrically powered bicycle trailer, by the way!
Personally, I would like a trailer like that, which mounts on its own on the hills. It should be the width of a supermarket cart a 3rd wheel for stability when you take it off the bike (to do the shopping and bring it all home).
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Alain G wrote:
There is nothing revolutionary in a simple variable resistance and a damped spring provided with an acceleration and deceleration adjustment which is done electronically by a simple capacitor.
Yeah well it's still a "force sensor" as you say. it therefore remains a resistance which varies according to the force that is applied to it.
Since you've been in the "load-cell" industry for 20 years (say you've worked 20 years in lots of areas it's crazy ...) you will explain to me the fundamental difference between a potentiometer that measures the deformation of a spring and a strain gauge (and yes if in French we use the term "strain gauge" rather than "force sensor" it is well to precisely name a very precise system)
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Be wary of word-for-word translationsAlain G wrote:I didn't look for the French term because we have always called this gadget a load cell which word for word translates as "load cell"
As much "load cell" is understandable for someone who knows a little about the subject, as much "load cell" is not at all the appropriate term for a French (not to mention the "that of load")
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absolutely
the exact translation of "load cell" is "strain gauge" point. In either case (or rather in one language as in the other) these terms designate a very specific force measurement technology.
a strain gauge is a force sensor, but a force sensor is not necessarily a strain gauge. (just like a convertible is a type of automobile, but an automobile is not necessarily a convertible)
In my opinion in English the distinction is there. I am not an English speaker and therefore I do not know exactly how they say for force sensor, but in my opinion it is closer to "force sensor" than "load cell": a load cell is a force sensor, but a force sensor isn't necessarily a load cell
Anyway, and from the start, the main problem was not to measure the horse's pulling force, we had already toured the different solutions, but the enslavement. And there again I think we had quite a bit of debate on what was applicable. Part of the technological choices had been made, all that remained was to assemble all of this.
The engineer who developed the machine did not use a different solution than what we had mentioned. He was simply determined to go all the way, motivated by the project, and gave himself the means to succeed.
An engineer, a fortiori an engineer in the arts and crafts, does not have specific training in traction control, he simply inquired, documented, he learned on the job and probably experienced a lot. (this is the basis of the engineering profession)
the exact translation of "load cell" is "strain gauge" point. In either case (or rather in one language as in the other) these terms designate a very specific force measurement technology.
a strain gauge is a force sensor, but a force sensor is not necessarily a strain gauge. (just like a convertible is a type of automobile, but an automobile is not necessarily a convertible)
In my opinion in English the distinction is there. I am not an English speaker and therefore I do not know exactly how they say for force sensor, but in my opinion it is closer to "force sensor" than "load cell": a load cell is a force sensor, but a force sensor isn't necessarily a load cell
Anyway, and from the start, the main problem was not to measure the horse's pulling force, we had already toured the different solutions, but the enslavement. And there again I think we had quite a bit of debate on what was applicable. Part of the technological choices had been made, all that remained was to assemble all of this.
The engineer who developed the machine did not use a different solution than what we had mentioned. He was simply determined to go all the way, motivated by the project, and gave himself the means to succeed.
An engineer, a fortiori an engineer in the arts and crafts, does not have specific training in traction control, he simply inquired, documented, he learned on the job and probably experienced a lot. (this is the basis of the engineering profession)
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Grelinette
- Econologue expert
- posts: 2007
- Registration: 27/08/08, 15:42
- Location: Provence
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Well, let's move on to this beginning of the beginning of an emerging controversy on the semantics of technical terms ...
A small clarification on a project entrusted to students: they are not alone. Students are supervised by teachers specializing in the disciplines covered and these teachers often also have a professional cap because some work for private companies.
Admittedly there are sometimes ways of work where the students get lost at the beginning, and letting them wade allows them to become aware of the errors. It is also true that the objective is above all educational to acquire knowledge, and economic research and simplicity is not necessarily the priority ... but hey, it's part of the game.
To return to the last more technical remarks:
Perhaps a simpler and more economical solution with a piezoelectric sensor http://fr.wikipedia.org/wiki/Pi%C3%A9zo%C3%A9lectricit%C3%A9
Indeed, the control loop was a determining point for the project, a simple trick helped to improve the principle.
http://fr.wikipedia.org/wiki/Asservisse ... matique%29
For the other interesting applications that can use this principle, I think it would be applicable from the bicycle trailer to the baby stroller, via the rolling suitcase
The student engineer presents his thesis in the coming days. I will no doubt have a copy of his brief.
A small clarification on a project entrusted to students: they are not alone. Students are supervised by teachers specializing in the disciplines covered and these teachers often also have a professional cap because some work for private companies.
Admittedly there are sometimes ways of work where the students get lost at the beginning, and letting them wade allows them to become aware of the errors. It is also true that the objective is above all educational to acquire knowledge, and economic research and simplicity is not necessarily the priority ... but hey, it's part of the game.
To return to the last more technical remarks:
Alain G wrote:... you kept the charging one which makes it very complicated and expensive to make your cart, what scares me is that someone else copies your idea but making it much simpler.
Perhaps a simpler and more economical solution with a piezoelectric sensor http://fr.wikipedia.org/wiki/Pi%C3%A9zo%C3%A9lectricit%C3%A9
BobFuck wrote:Alain G wrote:...
All the intelligence is in the mechanical assembly and especially the servo algorithm, on which I would like to have details, because it must be very interesting. Is the gadzar report online?
It could be transposed to an electrically powered bicycle trailer, by the way! ...
Indeed, the control loop was a determining point for the project, a simple trick helped to improve the principle.
http://fr.wikipedia.org/wiki/Asservisse ... matique%29
For the other interesting applications that can use this principle, I think it would be applicable from the bicycle trailer to the baby stroller, via the rolling suitcase
The student engineer presents his thesis in the coming days. I will no doubt have a copy of his brief.
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Project of the horse-drawn-hybrid - The project econology
"The search for progress does not exclude the love of tradition"
"The search for progress does not exclude the love of tradition"
-
Grelinette
- Econologue expert
- posts: 2007
- Registration: 27/08/08, 15:42
- Location: Provence
- x 272
I add a small remark to my previous comment about the algorithm used. We have made several calculation tests to control the wheel motors according to the force delivered by the horse.
In certain cases, the motor response is constant and regular, but the quality of assistance is lost when the horse provides a "collar stroke" ie when there is a peak in the traction (starting, acceleration like the passage of the not too much, ...).
Conversely, managing peaks deteriorates the quality of the engine response when the horse is installed at a constant pace.
A simple solution could be to have the possibility to select from among a few pre-established algorithms corresponding to specific traction situations (uphill, flat, sport course, walk, agricultural work, etc.), and the ideal would be an algorithm that s adapts "intelligently" to the situation and which is automatically enriched by measurements from past traction situations.
For example, an algorithm that analyzes peaks and attempts to remove them. A kind of artificial intelligence.
This would be all the more interesting as it would allow the system to also adapt to the type of harnessed horse (strong and slow draft horse, lively and fast thoroughbred, pony, ... even stubborn bum, lazy horse, etc. .
In short, there is still a lot of grain to grind with this project. We have already mentioned the possibility of improving the concept for version 2.0 of the hybrid carriage! If you have any ideas ...
In certain cases, the motor response is constant and regular, but the quality of assistance is lost when the horse provides a "collar stroke" ie when there is a peak in the traction (starting, acceleration like the passage of the not too much, ...).
Conversely, managing peaks deteriorates the quality of the engine response when the horse is installed at a constant pace.
A simple solution could be to have the possibility to select from among a few pre-established algorithms corresponding to specific traction situations (uphill, flat, sport course, walk, agricultural work, etc.), and the ideal would be an algorithm that s adapts "intelligently" to the situation and which is automatically enriched by measurements from past traction situations.
For example, an algorithm that analyzes peaks and attempts to remove them. A kind of artificial intelligence.
This would be all the more interesting as it would allow the system to also adapt to the type of harnessed horse (strong and slow draft horse, lively and fast thoroughbred, pony, ... even stubborn bum, lazy horse, etc. .
In short, there is still a lot of grain to grind with this project. We have already mentioned the possibility of improving the concept for version 2.0 of the hybrid carriage! If you have any ideas ...
0 x
Project of the horse-drawn-hybrid - The project econology
"The search for progress does not exclude the love of tradition"
"The search for progress does not exclude the love of tradition"
-
Grelinette
- Econologue expert
- posts: 2007
- Registration: 27/08/08, 15:42
- Location: Provence
- x 272
Forhorse wrote:Frankly, how much did the strain gauge cost?
What is its share in the overall cost of the project?
I have a vague idea but I prefer to let the author of the subject answer. From there, everyone has to judge ...
Well, without wanting to maintain the secret, I don't know it yet!
Quite simply because most of the materials used come from recovery (this is also the advantage of going through a school: we first look in the stock of materials recovered before buying).
On the other hand, I know that the previous students of electronic Bts who had worked on the project used an identical gauge with a capacity of 500 kg which was worth around 200 € each. (A special national education prize: another advantage of going through students!)
I just did a search on the internet: there is a very large choice of sensors of very different models and prices.
In addition, I think it may be interesting to undersize the capacities of the sensor for economic reasons and to insert it into a mechanical device (lever arm) which reduces the force applied to it? ... system that I tinkered with cheaply could work perfectly with a low capacity sensor:
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Project of the horse-drawn-hybrid - The project econology
"The search for progress does not exclude the love of tradition"
"The search for progress does not exclude the love of tradition"
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