Yes, talking a feeling or personal judgement is purely Subjective;
talking a DoF motion theory is Objective however.
talking a DoF motion theory is Objective however.
SimXperience GS-5 Seat
- Thread starter HugoB
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I know Rseat sold the 3250i D-Box system on some of their sims. This is a 3 actuator system with two at the back and one in the front.
On my own rig I get the problem that one foot lifts up with aggressive settings in certain situations.
I have 4 actuators.
I believe one of the claims is that it is more difficult to get lift off with 3 actuators. Taking Joe’s example with the LP player it’s more difficult to level with 4 contact points than 3. Because 4 has a possibility for wobble to occur while 3 even though not perfectly levelled will not wobble. As a sim rig with 4 actuator moves to extremes one foot might lift off even if the feet are perfectly levelled. This I can imagine will have an effect on how the sim is experienced as forces will be blunted as the weight is shifted around and/or the other actuators don’t move far or fast enough to keep the same relative degree of levelling between actuators in the new tilted orientation as it has while being levelled in a standby position (with the sim simulating a car on perfectly flat ground.)
I don’t quite understand Joe’s claim that a 4 actuator setup cannot simulate 3dof while a 3 actuator setup can. I would think they both could do it, but a 4 actuator setup might be less than optimal because in some way the simulator will “fight” with itself for the reasons I discussed above.
I’ve been struggling with my sim feeling to floaty for my taste if that makes sense. I’m going to order 4 brackets so I can attach my actuators to a 80/20 rig. When I get those I mean to experiment with different configurations to see if 2 actuators with a rear pivot or a 3 actuator setup will feel better as it relates to details transmitted and/or feeling of solidity.
On my own rig I get the problem that one foot lifts up with aggressive settings in certain situations.
I have 4 actuators.
I believe one of the claims is that it is more difficult to get lift off with 3 actuators. Taking Joe’s example with the LP player it’s more difficult to level with 4 contact points than 3. Because 4 has a possibility for wobble to occur while 3 even though not perfectly levelled will not wobble. As a sim rig with 4 actuator moves to extremes one foot might lift off even if the feet are perfectly levelled. This I can imagine will have an effect on how the sim is experienced as forces will be blunted as the weight is shifted around and/or the other actuators don’t move far or fast enough to keep the same relative degree of levelling between actuators in the new tilted orientation as it has while being levelled in a standby position (with the sim simulating a car on perfectly flat ground.)
I don’t quite understand Joe’s claim that a 4 actuator setup cannot simulate 3dof while a 3 actuator setup can. I would think they both could do it, but a 4 actuator setup might be less than optimal because in some way the simulator will “fight” with itself for the reasons I discussed above.
I’ve been struggling with my sim feeling to floaty for my taste if that makes sense. I’m going to order 4 brackets so I can attach my actuators to a 80/20 rig. When I get those I mean to experiment with different configurations to see if 2 actuators with a rear pivot or a 3 actuator setup will feel better as it relates to details transmitted and/or feeling of solidity.
metalnwood
Premium
Of course four actuators can produce 3dof, as long as we are agreeing what what degrees are, e.g., pitch, roll and heave. Which of course might be different than another 3dof simulator that uses yaw as one of it's degrees.
Really the deisgn of the system has more to do with it than how many actuators are being used. Dbox can have 4 actuators and produce 3dof, or with a different design 4 actuators can give you 4dof.
I don't understand what Joe is saying in this regard, that 4 can't do 3dof, its the design, not the number of actuators.
Really the deisgn of the system has more to do with it than how many actuators are being used. Dbox can have 4 actuators and produce 3dof, or with a different design 4 actuators can give you 4dof.
I don't understand what Joe is saying in this regard, that 4 can't do 3dof, its the design, not the number of actuators.
Sure they move the rig: roll, pitch, and heave. But dont mean of 3dof.
3dof means 3 Degree of Freedom. In other words, that three axises have to be independently (freely) move without constrain each other.
Say you have 3 actuators, in this case, given signals to the actuators instructing them to move to positions: x1, x2, and x3, respectively. 3dof of 3 actuators will have no problem to reach their positons. 4 actuators d-box conf just cannot get the positions x1, x2, x3, and x4, accurately, if not carefully designed in SW. The LP player 3 legs is a good example. You will never find a 4-leg LP player. If so, then you need SW and computer driven the 4 legs together in order to level the player.
3dof means 3 Degree of Freedom. In other words, that three axises have to be independently (freely) move without constrain each other.
Say you have 3 actuators, in this case, given signals to the actuators instructing them to move to positions: x1, x2, and x3, respectively. 3dof of 3 actuators will have no problem to reach their positons. 4 actuators d-box conf just cannot get the positions x1, x2, x3, and x4, accurately, if not carefully designed in SW. The LP player 3 legs is a good example. You will never find a 4-leg LP player. If so, then you need SW and computer driven the 4 legs together in order to level the player.
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metalnwood
Premium
I agree here, they should be able to freely move without constraint - You are saying that the only way you could properly achieve that is with a system of bodies but is that the only way to have axis move independently?
For example, a dbox style system sits flat and then pitches forward 20 degrees. Can the platform move up and down without changing the pitch? Yes. Can it roll 20 degrees left or right without changing the pitch? Yes it can. So it has 3 degrees of freedom that are independent.
Degrees of freedom is a concept, it's not tied to any mechanical implementation
Let's put this way, simple, we all know there are many ways to configure nDoF motion platforms. But the n has to be equal to the number of actuators (motors) to use. For an example, if you use 4 actuators (motors) trying to configure a rigid body in 3DoF motion, then you know right away it cannot, because the rigid body cannot move in 3 Degree Of Freedom driven by 4 actuators (motors). Similarly, you cannot use 7 actuators (motor) to achieve 6DoF rigid body motion. When you use an extra actuator (motor), you constrain the motion freedoms.
metalnwood
Premium
Sorry, dont know where to go from here. Degrees of freedom has a meaning outside of sim's and mechanics. To apply something specific as actuators to the meaning of degree of freedom is just not correct.
If you were to tell me that pitch cannot be changed without also changing roll or one of the other degrees then I would agree with you that the implementation doesn't fully support independent degrees. As we can change the roll while not changing the pitch then they are independent and it is irrelevant how that is achieved.
If we were to take your definition then we would have a very small number of designs and hexapod simulator would not count as its actuators are used in multiple degrees.
An airplane is considered something that has six degrees of freedom but mechanically it achieves its yaw, roll, pitch with elevators, ailerons and rudders. These are not independent of each other, I.e. you need to coordinate all to achieve the flight you want. The rudder doesnt just impact yaw, it will impact pitch and roll as all have some impact on each other.
So does that mean that an airplane doesn't do 6dof because mechanically it doesnt have controls that only change one thing? That seems to be the premise of your argument?
Edit, there is always the chance this is just semantics or not understanding each other. Maybe I should just ask in a 4 actuator dbox system, what is the 4th degree assuming 3 are roll, pitch, heave?
If you were to tell me that pitch cannot be changed without also changing roll or one of the other degrees then I would agree with you that the implementation doesn't fully support independent degrees. As we can change the roll while not changing the pitch then they are independent and it is irrelevant how that is achieved.
If we were to take your definition then we would have a very small number of designs and hexapod simulator would not count as its actuators are used in multiple degrees.
An airplane is considered something that has six degrees of freedom but mechanically it achieves its yaw, roll, pitch with elevators, ailerons and rudders. These are not independent of each other, I.e. you need to coordinate all to achieve the flight you want. The rudder doesnt just impact yaw, it will impact pitch and roll as all have some impact on each other.
So does that mean that an airplane doesn't do 6dof because mechanically it doesnt have controls that only change one thing? That seems to be the premise of your argument?
Edit, there is always the chance this is just semantics or not understanding each other. Maybe I should just ask in a 4 actuator dbox system, what is the 4th degree assuming 3 are roll, pitch, heave?
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That's just it. There is no 4th degree of freedom. 3DOF is a term to describe the axis that a motion platform is able to simulate. Joe seems to want to put a different meaning to DOF. That's fine. It doesn't apply to the term we use in sim racing to differentiate the capabilities of motion platform solutions.
Whether or not a 3 actuator build is more effective than a 4 actuator build I have no idea. I cannot understand how. Personally with 100mm of travel in my actuators for the SFX-100, I'd be very concerned having only a single actuator on the rear of my chassis. Especially with a V3 unit mounted in it.
Whether or not a 3 actuator build is more effective than a 4 actuator build I have no idea. I cannot understand how. Personally with 100mm of travel in my actuators for the SFX-100, I'd be very concerned having only a single actuator on the rear of my chassis. Especially with a V3 unit mounted in it.
metalnwood
Premium
I agree, I dont think there is a 4th degree on a 4 actuator dbox system but if he thinks 4 actuators means 4 degrees then it might shed light on where he is coming from if he says what that 4th degree might be 
I think he is saying that you don't get as good a feeling with 4 actuators compared to using 3. One in the middle on the rear and two like we have at the front with the SFX-100. To which I would say, have you tried both? Not read a post, I mean properly tried both?
If I believed everything I read in a Youtube video comment section I'd assume that every seat mover in existence is complete garbage and the only way anyone would consider using motion is if they were basically driving a real car. Oh and that of course everyone could also pay for this top of the line gear while typing said comments calling 'affordable' motion systems trash.
If I believed everything I read in a Youtube video comment section I'd assume that every seat mover in existence is complete garbage and the only way anyone would consider using motion is if they were basically driving a real car. Oh and that of course everyone could also pay for this top of the line gear while typing said comments calling 'affordable' motion systems trash.
Well, I don’t think you guys understand the DOF meaning in this regard.
Let’s try last example, say 4x D-box config, let’s fix 3 actuators’ positions at zero. In other words, send zero to them. Now, try to move the 4th actuator in any of amount x while keeping other three at zero. You will fail on this trial.
Now, for 3x case, you would not have this problem, because it is 3DOF config. You can freely move any one of thee actuators and independently regardless others. You can send arbitrary values x1,x2, and x3 to the actuators, they will accurately reach there, because of 3DOF.
Same as 2DOF, 4DOF.....,6DOF
——-
Say, you send data trying to move the rig in:
Roll 5 degree
Pitch 4 degree
Heave 1 inch.
The 3x config 3DoF will accurately produce that position. You will not be able to do that for 4x d-box config. Your rig will move but by no means of accuracy or a correct position if calculations are not specially taken care of such config. The 4 actuators will struggle. For racing sim, then you may yield false movement, unpredictable feel. The wrong heave would be especially sensitive, may feel like floating, etc.(although they are not visible to you), unless you have special SW taking into account this type of 4x configuration (x1, x2, x3, and x4) mapping to 3 dof: roll, pitch, heave correctly. I guess the D-box SW might have been specially designed for such 4x configuration, unlike the SimTool SW, which its calculations work for n drivers map to n DoF config (will not work with a case of n+1 drivers map to n DoF for a rigid body, such as 4x map to 3 DoF in this case).
Downside of the 4x D-Box type for 3DoF is that one just cannot add any arbitrary telemetry data to drivers, x1, x2, x3, and x4 since they are constrained each other per calculation map to 3DoF. Adding some vibration data with very small amplitude maybe OK. For 3x 3DoF config, one will not have such problem since all x1,x,2 and x3 are totally independent. This is why SimTool works 3 x but will not work for 4x 3Dof.
The video shown below demonstrated a problem as expected from using SimTool SW. This is same problem as described by PetroVitallini with his PRS200 in SimTool SW that one leg lift up:
Here is another one, you cannot see, but you can hear at 0:25 and 0:44 one leg lift up:
The 3 legs LP (record) player is good example I gave. You can freely independently adjust each leg to move the player in 3dof in order to level the player. Now, if 4 legs, then you cannot do that. You have to move all legs together in according with calculation in order to level the player. This is because all 4 legs are constrained each other in order to move the player in 3dof. If you move one or two or three legs only at same time, then you get other leg(s) lift up. This is why a LP player has only 3 legs.
Let’s try last example, say 4x D-box config, let’s fix 3 actuators’ positions at zero. In other words, send zero to them. Now, try to move the 4th actuator in any of amount x while keeping other three at zero. You will fail on this trial.
Now, for 3x case, you would not have this problem, because it is 3DOF config. You can freely move any one of thee actuators and independently regardless others. You can send arbitrary values x1,x2, and x3 to the actuators, they will accurately reach there, because of 3DOF.
Same as 2DOF, 4DOF.....,6DOF
——-
Say, you send data trying to move the rig in:
Roll 5 degree
Pitch 4 degree
Heave 1 inch.
The 3x config 3DoF will accurately produce that position. You will not be able to do that for 4x d-box config. Your rig will move but by no means of accuracy or a correct position if calculations are not specially taken care of such config. The 4 actuators will struggle. For racing sim, then you may yield false movement, unpredictable feel. The wrong heave would be especially sensitive, may feel like floating, etc.(although they are not visible to you), unless you have special SW taking into account this type of 4x configuration (x1, x2, x3, and x4) mapping to 3 dof: roll, pitch, heave correctly. I guess the D-box SW might have been specially designed for such 4x configuration, unlike the SimTool SW, which its calculations work for n drivers map to n DoF config (will not work with a case of n+1 drivers map to n DoF for a rigid body, such as 4x map to 3 DoF in this case).
Downside of the 4x D-Box type for 3DoF is that one just cannot add any arbitrary telemetry data to drivers, x1, x2, x3, and x4 since they are constrained each other per calculation map to 3DoF. Adding some vibration data with very small amplitude maybe OK. For 3x 3DoF config, one will not have such problem since all x1,x,2 and x3 are totally independent. This is why SimTool works 3 x but will not work for 4x 3Dof.
The video shown below demonstrated a problem as expected from using SimTool SW. This is same problem as described by PetroVitallini with his PRS200 in SimTool SW that one leg lift up:
Here is another one, you cannot see, but you can hear at 0:25 and 0:44 one leg lift up:
The 3 legs LP (record) player is good example I gave. You can freely independently adjust each leg to move the player in 3dof in order to level the player. Now, if 4 legs, then you cannot do that. You have to move all legs together in according with calculation in order to level the player. This is because all 4 legs are constrained each other in order to move the player in 3dof. If you move one or two or three legs only at same time, then you get other leg(s) lift up. This is why a LP player has only 3 legs.
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I knew there was a voice of reason just waiting to pop up somewhere.....
Oh hi, Hoi
Oh hi, Hoi
Guys, you are destroying the GS-5 topic. The whole 3 vs 4 actuators has nothing to do with the G-seat.
My option on what's better: The last time i checked a race car still has 4 wheels
Gotcha! But what else am I going to do while I wait for my G’s-5 to make its way across the Atlantic?
saxxon66
Micha
Ok guys, one last thing, at least from me, regarding the 3 vs 4 actuator setup.
You can do 3DOF with 3 actuators, and in theory it is the perfekt model.
But there are other factors that needs to be considered for a race car simulator.
I had a Simukit 3DOF Trimotion setup and built a Trimotion using the SFX-100 by the time only 3 of the 4 actuators were already built and I had to wait for the 4th.
It worked but it was not quite as good as the 4 actuator setup.
Here is my Simukit 3DOF Trimotion
3 Actuator Concerns:
- In a perfect 3 motor system you need a isosceles triangle setup. This is hard to implement. You can put a platform above it, but it will bring the center of gravity much higher as we like. So you need to build your system to be much more rigid -> heavier -> slower
- The load of the motors will be uneven. Typical Setup will have one motor in front or back.
For pitch/surge effects this one motor will have the load that the other two can share. And we have a lot of these effects in sim racing. So at the end the load was much higher for this one motor.
- Higher motor load on one motor will make it slower in acceleration and speed than the other two, leading to an unsynchronized experience or an overall slower system.
- You can feel the position of the motors, for example I had a better feeling having 2 on the back and one in front. And having 4 of them you can feel it also, for small, fast movements, you can detect their origin pretty good.
3 Actuator Pro:
- It is 1/4 cheaper than 4 actuators
- Feeling with the SFX-100 was quite good
4 Actuators = 4DOF
You can do it by implementing a TriMotion System with Rear Traction loss. Heave, Surge, Sway, Yaw.
But in the end a 4 actuator setup is the real deal, like Hoi said, look at the real car ...
You can do 3DOF with 3 actuators, and in theory it is the perfekt model.
But there are other factors that needs to be considered for a race car simulator.
I had a Simukit 3DOF Trimotion setup and built a Trimotion using the SFX-100 by the time only 3 of the 4 actuators were already built and I had to wait for the 4th.
It worked but it was not quite as good as the 4 actuator setup.
Here is my Simukit 3DOF Trimotion
3 Actuator Concerns:
- In a perfect 3 motor system you need a isosceles triangle setup. This is hard to implement. You can put a platform above it, but it will bring the center of gravity much higher as we like. So you need to build your system to be much more rigid -> heavier -> slower
- The load of the motors will be uneven. Typical Setup will have one motor in front or back.
For pitch/surge effects this one motor will have the load that the other two can share. And we have a lot of these effects in sim racing. So at the end the load was much higher for this one motor.
- Higher motor load on one motor will make it slower in acceleration and speed than the other two, leading to an unsynchronized experience or an overall slower system.
- You can feel the position of the motors, for example I had a better feeling having 2 on the back and one in front. And having 4 of them you can feel it also, for small, fast movements, you can detect their origin pretty good.
3 Actuator Pro:
- It is 1/4 cheaper than 4 actuators
- Feeling with the SFX-100 was quite good
4 Actuators = 4DOF
You can do it by implementing a TriMotion System with Rear Traction loss. Heave, Surge, Sway, Yaw.
But in the end a 4 actuator setup is the real deal, like Hoi said, look at the real car ...
When i see a video like that i always wonder why would someone invest in high-end motion rig and still use a G27 and TV that is miles away from the rig
( hope i'm not offending anyone )Motion does look great though
Backup on topic:
@Magiashkii, how's the travel of the panels of the GS-5 compared to your old GS-4. Is it less because of the cam mechanism?
Also how's the noise level?
I read this quote today:
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saxxon66
Micha
When i see a video like that i always wonder why would someone invest in high-end motion rig and still use a G27 and TV that is miles away from the rig
Motion does look great though
Backup on topic:
@Magiashkii, how's the travel of the panels of the GS-5 compared to your old GS-4. Is it less because of the cam mechanism?
Also how's the noise level?
I read this quote today:
Sounds like the typical stepper motor high frequency pitching sound.
Swapping them against servo Motors will solve this problem, but will cost much more (~$100/motor).
Just checked my shipping details for the G’s-5. It says package is 38 kg. Don’t know how much of that is packaging. I would guess anywhere between 30 to 38 then
Max weight limit on a NLR V3 is 130kg so I'd be well under that with the GS-5 included. Interesting.
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