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The M30x/MCCC/Lumberbar

Started by Chris_Beeves, May 06, 2019, 09:07:40 PM

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Chris_Beeves

I'd go with hall sensors if I was going to try doing it again. They're cheap and quite easy to work with, but the whole concept works better in the imagination than irl I think.

If (when) I start working with motion I think I'll just rather move the whole rig. Seat and all. Combined with VR I don't think the movements need to be very large. But that will have to wait.

Next on my list is finishing the wireless knee sliders and trying to borrow a VR headset. That will pretty much finish the first stage of this project.
I had to try..

Vini

Quote from: Chris_Beeves on May 13, 2020, 08:45:39 PMIf (when) I start working with motion I think I'll just rather move the whole rig. Seat and all. Combined with VR I don't think the movements need to be very large. But that will have to wait.
I think a full motion rig with moving seat would actually feel less real because of the lack of G-forces. You would constantly be fighting gravity when hanging off because it cannot be countered by cornering forces.

Chris_Beeves

Quote from: Vini on May 13, 2020, 09:19:31 PMI think a full motion rig with moving seat would actually feel less real because of the lack of G-forces. You would constantly be fighting gravity when hanging off because it cannot be countered by cornering forces.

We can always play with the g-force that we DO have. The 9,82m/s^2 straight down. If you keep that straight under you when hanging off it should in theory fool the mind if you're using VR.  So if you tilt the bike left when going right, the force vector of gravity should be in the same(ish) direction as the cornering force would be.. I don't know if this is possible to implement yet, but I look forward to trying in the future. :)
I had to try..

Vini

May 13, 2020, 09:56:53 PM #78 Last Edit: May 13, 2020, 10:33:52 PM by Vini
You don't feel lateral forces when riding a real bike, though. The leaning always makes the resulting force vector acting on your body (gravity + cornering force) point straight into the seat.

This means that any leaning of the seat without the corresponding cornering force will result in an incorrect force vector that's not pointing straight into the seat anymore.

The way you are currently sitting on your chair is already simulating the appropriate (lateral) forces required to trick your brain.
All that is missing is the relative movement between the bars and you, which would be achieved by the having the handlebar swivel around/under you.

Chris_Beeves

May 14, 2020, 04:24:00 AM #79 Last Edit: May 14, 2020, 05:45:06 AM by Chris_Beeves
Quote from: Vini on May 13, 2020, 09:56:53 PMYou don't feel lateral forces when riding a real bike, though. The leaning always makes the resulting force vector acting on your body (gravity + cornering force) point straight into the seat.

This means that any leaning of the seat without the corresponding cornering force will result in an incorrect force vector that's not pointing straight into the seat anymore.

The way you are currently sitting on your chair is already simulating the appropriate (lateral) forces required to trick your brain.
All that is missing is the relative movement between the bars and you, which would be achieved by the having the handlebar swivel around/under you.

That would be true when you're sitting perfectly still an upright on your seat.
When I drive on track, I don't do that. So when I drive a simulator, I don't want to do that. I want to hang off!  :P
I also need to hang off in order to control the rider with trackIR, and in the future VR.

Riding a right corner and hanging off, the resulting force of gravity, acceleration and centripetal acceleration would not point straight down through the bike. Rather at an angle pointing from the right side of the bike somewhere through it's center (depending on how much you hang off and your weight). To replicate that force when standing still (in a simulator for example), you would need to lean the whole bike to the left, not just the handlebars. Am I making sense?

If I didn't draw like a two-year-old, a sketch would probably help..
Buuuut, this is probably a discussion for another thread, another time. :)
I had to try..

maggikk22

I agree with Vini: you have to fight against gravity all the time.
Even when you look at professional simulators such as the moto trainer (even if you don't control the rider), the overall feeling seems to be that the bike is too heavy.
If i want to be bad, it is more a gym machine than a bike simulator. Have you seen these videos showing the MotoGP riders trying to lean the bike left-right as many times as possible?

I tried to make a similar full motion simulator, using a big DC motor and springs to help with gravity issues.
It worked not bad, but it required better electronics skills and different (more expensive) hardware to improve the feeling.


Vini

May 14, 2020, 01:18:48 PM #81 Last Edit: May 14, 2020, 03:36:01 PM by Vini
Quote from: Chris_Beeves on May 14, 2020, 04:24:00 AMThat would be true when you're sitting perfectly still an upright on your seat.
The extra forces you generate by hanging off are the same whether you hang off your stationary chair or hang off a real bike while riding, it's just gravity. Therefore these forces don't have to be considered in the design of the simulator/controller. Note that we are talking about the forces acting on you, not the forces acting on the bike, which would be influenced by the overall shift in center of gravity produced by hanging off.

Quote from: Chris_Beeves on May 14, 2020, 04:24:00 AMRiding a right corner and hanging off, the resulting force of gravity, acceleration and centripetal acceleration would not point straight down through the bike. Rather at an angle pointing from the right side of the bike somewhere through it's center (depending on how much you hang off and your weight).
This slight change in angle is exactly what you get when you hang off your chair: A bit of "extra" gravity pulling you slightly away from (the center of) your seat instead of merely pointing straight into it.

Your idea of tilting the bike in the opposite direction would result in a very strange feeling because even though the relative position to the bike might be correct, your sense of balance would know that something is wrong. Your inner ear could tell that your body is leaning. On a real bike, this is not the case because the cornering force counteracts the gravity acting on your inner ear, resulting in your sense of balance always staying aligned to the bike.
If you closed your eyes while riding piggyback you would not be able to tell how far the bike is leaning.
This means that for your simulator, your body cannot be leaning at all because any sense of tilt would be wrong.


I will stop with the off-topic now but you are actually way closer to the "perfect simulation" than you might think.

h106frp

I wonder if one of these gyroscopic wheels would assist with a full size simulator?

Chris_Beeves

May 15, 2020, 09:50:53 AM #83 Last Edit: May 15, 2020, 10:12:00 AM by Chris_Beeves
Quote from: maggikk22 on May 14, 2020, 12:53:39 PMI agree with Vini: you have to fight against gravity all the time.
Even when you look at professional simulators such as the moto trainer (even if you don't control the rider), the overall feeling seems to be that the bike is too heavy.

That's exactly my point. The likes of moto trainer just ignores the lack of external forces. It's like a mechanical bull, nothing like racing a bike.

Love your rig! Must weigh half a ton?

Quote from: Vini on May 14, 2020, 01:18:48 PMThe extra forces you generate by hanging off are the same whether you hang off your stationary chair or hang off a real bike while riding, it's just gravity. Therefore these forces don't have to be considered in the design of the simulator/controller. Note that we are talking about the forces acting on you, not the forces acting on the bike, which would be influenced by the overall shift in center of gravity produced by hanging off.
I disagree with you here. When racing a real bike (not just riding) it's not "just gravity". It is the resulting force I'm talking about. I had my inner three-year-old sketch it up for me:

You cannot see attachments on this board.

The important thing to keep in mind here is that in real life we have L+g. That makes the percieved resulting force = R
In my seat by the computer, sadly I don't have access to an L. However, I can't just remove it from the equation (like you can see it the fatal second row incident). We need to replicate R, like in the third row.
Again, all this is only applicable if you want to lean off your seat/chair/rig.

Quote from: Vini on May 14, 2020, 01:18:48 PMThis slight change in angle is exactly what you get when you hang off your chair: A bit of "extra" gravity pulling you slightly away from (the center of) your seat instead of merely pointing straight into it.

Your idea of tilting the bike in the opposite direction would result in a very strange feeling because even though the relative position to the bike might be correct, your sense of balance would know that something is wrong. Your inner ear could tell that your body is leaning. On a real bike, this is not the case because the cornering force counteracts the gravity acting on your inner ear, resulting in your sense of balance always staying aligned to the bike.

What you are explaining here is exactly what leaning the bike the "wrong way" would remedy (Only applicable when hanging off your chair). Again, we have to replicate the resulting force "R" by only using the availible force "g", which needs to be pointing the same way "R" would. To do this, we rotate whatever you are sitting on the -(angle) of R.

Quote from: Vini on May 14, 2020, 01:18:48 PMIf you closed your eyes while riding piggyback you would not be able to tell how far the bike is leaning.
This means that for your simulator, your body cannot be leaning at all because any sense of tilt would be wrong.

This also only applies if your'e sitting perfectly straight on the bike. In that case, no lean movement is necessary, I agree to that.

Quote from: Vini on May 14, 2020, 01:18:48 PMI will stop with the off-topic now but you are actually way closer to the "perfect simulation" than you might think.

Me too, soon, but first my inner child couldn't help sketching what he thinks is strange with Swivel:

You cannot see attachments on this board.

(Maybe a paralell movement would be closer to real life, but harder to make)
I had to try..

Chris_Beeves

This shows the feel of the controller and the head tracking a bit better I think.

I had to try..

Vini

Good video, really shows the realism much better!


Regarding our physics discussion, the differentiation between hanging off and not hanging off is fundamentally wrong. Just think it a step further: It would mean that there is a special distance to the bike you need to achieve at all times in order to hit the sweet spot where the force simulation is accurate. Any deviation from that would result in an incorrect feeling. The extra forces created by hanging off are purely created by your own positioning while the external forces acting on the bike-rider (or simulator-player) system as a whole remain the same.
You are also not hanging off everytime the bike is leaning, for example when swerving around on a straight you are fully tucked in.
Lastly, your differentiation would mean that the physics are not continuous which cannot be true: The force calculation at the transition away from exactly 0° lean angle would change instantaneously in order to reflect your theory on the influence of hanging off.

The swivel design is a compromise in order to replicate some of the relative movements hanging off and leaning produces on a real bike. The mounting height and the bike-lean-angle-to-controller-swivel-angle-scaling need to be finetuned, which is not being properly reflected in your sketches.
If they are correctly adjusted, the movements between your head (which is where most of your senses come from) and the handlebar would be quite close to reality:

Chris_Beeves

Quote from: Vini on May 17, 2020, 06:32:25 PMGood video, really shows the realism much better!

Thank you!

Quote from: Vini on May 17, 2020, 06:32:25 PMRegarding our physics discussion, the differentiation between hanging off and not hanging off is fundamentally wrong. Just think it a step further: It would mean that there is a special distance to the bike you need to achieve at all times in order to hit the sweet spot where the force simulation is accurate. Any deviation from that would result in an incorrect feeling.

I can see that I'm failing to communicate what it is that I mean. I'm not saying there is a "correct" hang off amount. I agree with you that as it is now, any hanging off messes up the sense of balance. Leaning the simulator rig in the direction you are turning would make that even worse. Leaning it too much in the other direction would mess it up equally. I'm enjoying this discussion a lot, you make good points!
Do you agree with me that, if you were to lean a motion rig in any direction, it would be the opposite way of the turn?

Quote from: Vini on May 17, 2020, 06:32:25 PMThe extra forces created by hanging off are purely created by your own positioning while the external forces acting on the bike-rider (or simulator-player) system as a whole remain the same.

The shift in the rider's center of gravity affects the lean angle of the bike you need to make a given turn at a given speed. So even if the external forces are the same, the relation between the internal forces are different (lean angle/hang off = constant, or something like that)

Quote from: Vini on May 17, 2020, 06:32:25 PMYou are also not hanging off everytime the bike is leaning, for example when swerving around on a straight you are fully tucked in.
Lastly, your differentiation would mean that the physics are not continuous which cannot be true: The force calculation at the transition away from exactly 0° lean angle would change instantaneously in order to reflect your theory on the influence of hanging off.

Yeah, that is a good point too. A depth mapping sensor would be required to get a somewhat correct assuption of rig lean.. Maybe that could keep the lean/hang ratio constant (or just tap into the trackIR data..). I'd like to go hang out at Cruden for a year or so to try stuff out..

Quote from: Vini on May 17, 2020, 06:32:25 PMThe swivel design is a compromise in order to replicate some of the relative movements hanging off and leaning produces on a real bike. The mounting height and the bike-lean-angle-to-controller-swivel-angle-scaling need to be finetuned, which is not being properly reflected in your sketches.
If they are correctly adjusted, the movements between your head (which is where most of your senses come from) and the handlebar would be quite close to reality:


Your sketch is a lot better than mine! ;)
I feel that the radius required to make the swivel work for my riding style would make it very difficult to fabricate. This is just my stuborn mind though, I haven't tried it, so I can't really say.
I had to try..

Vini

May 17, 2020, 11:30:43 PM #87 Last Edit: May 17, 2020, 11:37:16 PM by Vini
Quote from: Chris_Beeves on May 17, 2020, 08:37:47 PMDo you agree with me that, if you were to lean a motion rig in any direction, it would be the opposite way of the turn?
Yes, definitely.
By your logic, you'd have to move the simulator in such a way that it precisely counteracts your own movements so that your body stays vertical. But then hanging off and not hanging off would feel the same way which is not accurate either since hanging off in reality requires effort against gravity (which you feel quite clearly in your inside knee). So I come to the conclusion that there shouldn't be any tilting at all, except the one you produce yourself by moving away from your chair, meaning the seat stays stationary.

Quote from: Chris_Beeves on May 17, 2020, 08:37:47 PMThe shift in the rider's center of gravity affects the lean angle of the bike you need to make a given turn at a given speed. So even if the external forces are the same, the relation between the internal forces are different (lean angle/hang off = constant, or something like that)
This is what I was talking about earlier and which confused me as well: For the design of your simulator, you need to stay in the reference frame of the rider, which is the opposite of all those motorcycle vector sketches you find in literature. The fact that hanging off allows the bike-rider system as a whole to turn faster or the fact that it reduces the bike's lean angle is not relevant to the forces the rider experiences (or at least it's negligible).

The only forces you consciously experience are the ones you have to actively resist.
When staying stationary in the seat, the combination of gravity and cornering force pushes your straight in the seat, requiring no resisting on your part.
As soon as you hang off (your lower body), gravity pulls you away from the bike requiring effort to stay seated. The cornering force on the other hand still pushes you into the bike, meaning the only force you have to resist is the gravity pointing straight down, which is exactly the same you currently have to resist when moving out of your stationary chair.

Quote from: Chris_Beeves on May 17, 2020, 08:37:47 PMI feel that the radius required to make the swivel work for my riding style would make it very difficult to fabricate.
Still a lot easier to build than a full motion bike rig, though ;D

Chris_Beeves

Quote from: Vini on May 17, 2020, 11:30:43 PMBy your logic, you'd have to move the simulator in such a way that it precisely counteracts your own movements so that your body stays vertical. But then hanging off and not hanging off would feel the same way which is not accurate either since hanging off in reality requires effort against gravity

I think this is where our opinions (enterpretations of reality) differ.
If I'm going in a straight line and hanging off, all I'm doing is moving my g-vector from pointing straight down through the bike to the side of it paralell to the bike's g-vector. Moving requires effort ,being a large mammal like myself, and staying there without cornering requires strength to hang on.
Then when I start to lean the bike, the lateral forces, or rather centripetal acceleration, comes into play. The body can't tell the difference or separate these forces, so if I were to close my eyes at this moment (scary thought), I wouldn't be able to accurately point out the direction of gravitation. We agree on that too?

Quote from: Vini on May 17, 2020, 11:30:43 PMThis is what I was talking about earlier and which confused me as well: For the design of your simulator, you need to stay in the reference frame of the rider, which is the opposite of all those motorcycle vector sketches you find in literature. The fact that hanging off allows the bike-rider system as a whole to turn faster or the fact that it reduces the bike's lean angle is not relevant to the forces the rider experiences (or at least it's negligible).

I say it's highly relevant. The difference in hanging off a bike going in a straight line and one cornering is indeed noticable.

Quote from: Vini on May 17, 2020, 11:30:43 PMThe only forces you consciously experience are the ones you have to actively resist.
When staying stationary in the seat, the combination of gravity and cornering force pushes your straight in the seat, requiring no resisting on your part.
As soon as you hang off (your lower body), gravity pulls you away from the bike requiring effort to stay seated.
Up until here we are pretty much on the same page.
I still think that hanging off going straight and hanging off in a corner makes a difference in experience though. 

Quote from: Vini on May 17, 2020, 11:30:43 PMThe cornering force on the other hand still pushes you into the bike, meaning the only force you have to resist is the gravity pointing straight down, which is exactly the same you currently have to resist when moving out of your stationary chair.

If your perception could separate those forces, yes! What I'm saying is you can't just pull the cornering force out of the equation and not replace it with anything if you want to maintain (quasi-) equilibrium. I'll make a sketch of it and try to calculate. Maybe I'll find that I'm wrong! :D

Quote from: Vini on May 17, 2020, 11:30:43 PMStill a lot easier to build than a full motion bike rig, though ;D

Indeed, but it solves a problem I don't have ;D
I had to try..

Vini

May 18, 2020, 05:38:54 PM #89 Last Edit: May 18, 2020, 05:43:00 PM by Vini
Quote from: Chris_Beeves on May 18, 2020, 08:43:53 AMIf I'm going in a straight line and hanging off [...]
Then when I start to lean the bike, the lateral forces, or rather centripetal acceleration, comes into play. The body can't tell the difference or separate these forces, so if I were to close my eyes at this moment (scary thought), I wouldn't be able to accurately point out the direction of gravitation. We agree on that too?
No, this is exactly where we disagree. The centripetal force only "cancels out" (your perception of) gravity when you are staying seated (hence my example of riding piggyback with eyes closed). Only in this case, do the sum of all forces acting on you require no active effort to resist. Even when leaning 40° or more, hanging off requires effort, specifically in your inside leg/knee to support your body against (vertical) gravity. This is pretty easy to test.

Quote from: Chris_Beeves on May 18, 2020, 08:43:53 AM
Quote from: Vini on May 17, 2020, 11:30:43 PMThe only forces you consciously experience are the ones you have to actively resist.
When staying stationary in the seat, the combination of gravity and cornering force pushes your straight in the seat, requiring no resisting on your part.
As soon as you hang off (your lower body), gravity pulls you away from the bike requiring effort to stay seated.
Up until here we are pretty much on the same page.
I still think that hanging off going straight and hanging off in a corner makes a difference in experience though.
Not because the underlying forces change, though. The force you have to resist in both cases is exactly the same: gravity pulling you straight down and away from the bike. The difference when the bike is leant over is that your outside leg is automatically anchoring you to the bike and resisting the pull of gravity, so it does not require as much conscious effort from your inside leg.

Quote from: Chris_Beeves on May 18, 2020, 08:43:53 AM
Quote from: Vini on May 17, 2020, 11:30:43 PMThe cornering force on the other hand still pushes you into the bike, meaning the only force you have to resist is the gravity pointing straight down, which is exactly the same you currently have to resist when moving out of your stationary chair.
If your perception could separate those forces, yes! What I'm saying is you can't just pull the cornering force out of the equation and not replace it with anything if you want to maintain (quasi-) equilibrium.
Your perception does not have to separate the forces, physics does that. I am not pulling the cornering force out of the equation, it is simply being counteracted by the presence of the bike and its traction force.
Hanging off means that you no longer are in equilibrium, that is the whole point of it: You add "extra gravity" to the bike-rider system, which allows the bike to stay at a smaller lean angle (or higher velocity) in order to maintain the new equilibrium. The bike-rider system as a whole always stays in equilibrium but as soon as you start hanging off, you separate your body from this equilibrium.
Another way to look at it is this: The force with which you push yourself up to resist gravity when hanging off is equal to the force that pushes the bike down and therefore allows it to corner faster while keeping the same lean angle (Newton's third law). The further you move out of the equilibrium (where gravity + cornering force aligns with the bike), the more you have to "push the bike into the corner" and the faster it can turn.

This, again, is similar to the physics you experience when hanging off your stationary chair: The further you move your CoG away from the support of the chair, the more you have to push with your inside leg to resist falling down.
The only difference is that you cannot anchor yourself with the other leg (as described earlier), which makes it harder than it would be in reality.
So you need a seat which you can grip well with your legs no matter how far you hang off.