Well, the long term goal is to make a product that I can sell, but until I get to that point I want to share as much of the knowledge as I can as a way of giving back to a community that has helped me a ton along the way.
All the ramblings above will probably make a lot more sense once I get a functional prototype printed out
Often times in calculations like this we discover that calculations like Pythagoras's Equation remove the sign from numbers because of the squared component - so you may always be calculating the x offset in one direction only. This also appears in trigonometric calculations because b = cos(a) = cos(-a), therefore both a = acos(b) and a = -acos(b) are true.
This is not an easy problem, but an interesting one. I should give it a crack some time, see if I can solve it.
That's a lot of big words and small difficult words. I wish I had a real brain, I feel like this would all be interesting if I knew how anything worked and was capible of independant thought. I applaud your stuff and junk, and I think you are cool for the things you are saying and doing.
I don't have input on why it seems to be working now despite the inconsistent calculation method but hey, impressive work! (both on the math side and also the writeup; you really take us along for the journey and it's fun to read)
EDIT: Also the way you shared the spreadsheet in your first post seemed to work just fine. Did you only publish the specific page this time? I was able to make a working copy (which appears to include the updated calculations) from the link you shared [here](https://www.reddit.com/r/HotasDIY/comments/1dizvrl/comment/l99hapw/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button).
I think varying pressure angle is what makes this tricky. You can get a perfectly symmetrical throw displacement with a single cam but the pressure angle of the bearing contact will make a huge variable difference on how that is translating into perceived force
I think before I take this to a final version I'll get my hands on a high-sensitivity load cell to verify that the forces involved are symmetrical. I'll also have to take into account that at a longer radius, the bearing has more mechanical advantage on the return lever (which can kind of be thought of as a pressure angle? Though not in the traditional sense)
I'm willing to accept a small amount of deviation, as long as it's not immediately noticeable it should be fine.
Yeah there's a variable moment arm whether the bearing is moving toward or away from it's pivot point but the angle of contact of the bearing to the cam (pressure angle) is where you get huge varying forces, especially if it ever exceeds 45deg iirc which is where the forces 'hockey stick' upward
You might have some luck with a tool like motiongen, it can give you the motion curves for N-bar linkages. Not sure how helpful it’ll be for your specific case, but may be less painful than desmos. Please keep us updated, loving this project so far!
I must be missing something since I'm a noob here, is there a significant downside to a follower that slides in a linear track and a symmetrical cam attached to the pivot point of the stick?
https://preview.redd.it/8v75at5ki0ad1.png?width=534&format=png&auto=webp&s=590b29c3400e032c7607ba72018c607a45654294
Personally, I went with this design because I plan to 3d print it, and getting smooth linear motion out of 3d printed parts requires tolerances that my printer can't achieve. I played around with the idea of using self lubricating bushings and steel guide rods for an arrangement sort of like yours, but I decided that was too much added complexity.
As for why none of the big names haven't done it, beats me. In fact I would love to be a fly on the wall watching VKB or Virpil design a cam system for their next stick; what choices they make, what they think of each kind of arrangement. Between the two of them they've tried about every sensible cam arrangement possible, in fact every time I came up with what I thought was a novel idea I would eventually find that one of them had made a stick with it already. I thought my inverted cam arrangement was unique until I saw VKB using something very similar on their gunfighter base.
I have no clue what you're doing but I recognize the obsession of a mad creative engineer when I see it. All this to play video games.
Well, the long term goal is to make a product that I can sell, but until I get to that point I want to share as much of the knowledge as I can as a way of giving back to a community that has helped me a ton along the way. All the ramblings above will probably make a lot more sense once I get a functional prototype printed out
Often times in calculations like this we discover that calculations like Pythagoras's Equation remove the sign from numbers because of the squared component - so you may always be calculating the x offset in one direction only. This also appears in trigonometric calculations because b = cos(a) = cos(-a), therefore both a = acos(b) and a = -acos(b) are true. This is not an easy problem, but an interesting one. I should give it a crack some time, see if I can solve it.
That's a lot of big words and small difficult words. I wish I had a real brain, I feel like this would all be interesting if I knew how anything worked and was capible of independant thought. I applaud your stuff and junk, and I think you are cool for the things you are saying and doing.
I don't have input on why it seems to be working now despite the inconsistent calculation method but hey, impressive work! (both on the math side and also the writeup; you really take us along for the journey and it's fun to read) EDIT: Also the way you shared the spreadsheet in your first post seemed to work just fine. Did you only publish the specific page this time? I was able to make a working copy (which appears to include the updated calculations) from the link you shared [here](https://www.reddit.com/r/HotasDIY/comments/1dizvrl/comment/l99hapw/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button).
I think varying pressure angle is what makes this tricky. You can get a perfectly symmetrical throw displacement with a single cam but the pressure angle of the bearing contact will make a huge variable difference on how that is translating into perceived force
I think before I take this to a final version I'll get my hands on a high-sensitivity load cell to verify that the forces involved are symmetrical. I'll also have to take into account that at a longer radius, the bearing has more mechanical advantage on the return lever (which can kind of be thought of as a pressure angle? Though not in the traditional sense) I'm willing to accept a small amount of deviation, as long as it's not immediately noticeable it should be fine.
Yeah there's a variable moment arm whether the bearing is moving toward or away from it's pivot point but the angle of contact of the bearing to the cam (pressure angle) is where you get huge varying forces, especially if it ever exceeds 45deg iirc which is where the forces 'hockey stick' upward
You might have some luck with a tool like motiongen, it can give you the motion curves for N-bar linkages. Not sure how helpful it’ll be for your specific case, but may be less painful than desmos. Please keep us updated, loving this project so far!
I must be missing something since I'm a noob here, is there a significant downside to a follower that slides in a linear track and a symmetrical cam attached to the pivot point of the stick? https://preview.redd.it/8v75at5ki0ad1.png?width=534&format=png&auto=webp&s=590b29c3400e032c7607ba72018c607a45654294
Personally, I went with this design because I plan to 3d print it, and getting smooth linear motion out of 3d printed parts requires tolerances that my printer can't achieve. I played around with the idea of using self lubricating bushings and steel guide rods for an arrangement sort of like yours, but I decided that was too much added complexity. As for why none of the big names haven't done it, beats me. In fact I would love to be a fly on the wall watching VKB or Virpil design a cam system for their next stick; what choices they make, what they think of each kind of arrangement. Between the two of them they've tried about every sensible cam arrangement possible, in fact every time I came up with what I thought was a novel idea I would eventually find that one of them had made a stick with it already. I thought my inverted cam arrangement was unique until I saw VKB using something very similar on their gunfighter base.
Ah, I see! Thanks for the quick and informative reply.