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Cable Robot Simulator [video]

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Re: Cable Robot Simulator [video]

#11

Post by darkmighty »

udev wrote: post #7
jameshart wrote: post #5

This seems like a poor fit for VR motion simulation - actual movement through space is generally unnecessary, you just need to gimbal the platform to simulate accelerations. Actual linear acceleration is of limited value in simulation because you can't maintain that acceleration indefinitely - you run out of room and have to apply an opposite acceleration, which can conflict with the simulation needs. On the other ha…

I agree that rotation should be enough for VR purposes, and linear translation of the subject is not strictly necessary. Any acceleration up to g = 9.81 m / s^2 can be easily simulated, and it can be maintained indefinitely. All you need to do is to rotate the subject so that the perceived acceleration is aligned with g, or keep it at an angle, to get a fraction of g. Interestingly, for VR you don't need to simulate…

Not up to 1g acceleration, exactly 1g aceleration only (if the platform only rotates), with varying direction.

Re: Cable Robot Simulator [video]

#13

Post by jessriedel »

udev wrote: post #7
jameshart wrote: post #5

This seems like a poor fit for VR motion simulation - actual movement through space is generally unnecessary, you just need to gimbal the platform to simulate accelerations. Actual linear acceleration is of limited value in simulation because you can't maintain that acceleration indefinitely - you run out of room and have to apply an opposite acceleration, which can conflict with the simulation needs. On the other ha…

I agree that rotation should be enough for VR purposes, and linear translation of the subject is not strictly necessary. Any acceleration up to g = 9.81 m / s^2 can be easily simulated, and it can be maintained indefinitely. All you need to do is to rotate the subject so that the perceived acceleration is aligned with g, or keep it at an angle, to get a fraction of g. Interestingly, for VR you don't need to simulate…

You can't do brief periods of weightlessness with rotations on a gimbal, or periods of larger than 1 g.

Re: Cable Robot Simulator [video]

#15

Post by vpribish »

eatonphil wrote: post #12

Hopefully not a completely ridiculous question, is there any chance cable technology like this could be used as public transportation in the future similar to in Pixar's Robots?

Come visit beautiful San Francisco! https://en.wikipedia.org/wiki/San_Francisco_cable_car_system

I think the wires would get in each other's way if you had pods in the same volume.

Re: Cable Robot Simulator [video]

#16

Post by ghgr »

jameshart wrote: post #5

This seems like a poor fit for VR motion simulation - actual movement through space is generally unnecessary, you just need to gimbal the platform to simulate accelerations. Actual linear acceleration is of limited value in simulation because you can't maintain that acceleration indefinitely - you run out of room and have to apply an opposite acceleration, which can conflict with the simulation needs. On the other ha…

I've been working with full motion simulators for the past two years (I even rode that simulator last week at MPI) and I must say that this is plain wrong. This is actually a great fit for VR simulation (see below):

> Actual linear acceleration is of limited value in simulation because...

Linear acceleration is immensely useful for sudden accelerations. Image a sudden linear acceleration (e.g. a racing car accelerating). You cannot recreate this acceleration by suddenly rotating. The angular accelerations would ruin the experience. Rather, you make a linear movement, and THEN you rotate the simulator (if you need to sustain the acceleration).

> you run out of room and have to apply an opposite acceleration, which can conflict with the simulation needs.

wrong again. If you move the simulator at slow speed, you can actually come back to the optimal position and the subject does not notice it (washout filter [1])

[1] https://en.wikipedia.org/wiki/Motion_simulator#Implementatio...

Re: Cable Robot Simulator [video]

#17

Post by eatonphil »

vpribish wrote: post #15
eatonphil wrote: post #12

Hopefully not a completely ridiculous question, is there any chance cable technology like this could be used as public transportation in the future similar to in Pixar's Robots?

Come visit beautiful San Francisco! https://en.wikipedia.org/wiki/San_Francisco_cable_car_system I think the wires would get in each other's way if you had pods in the same volume.

Ah of course, that was silly of me. I guess I meant suspended cable travel.

Re: Cable Robot Simulator [video]

#18

Post by nbadg »

eatonphil wrote: post #12

Hopefully not a completely ridiculous question, is there any chance cable technology like this could be used as public transportation in the future similar to in Pixar's Robots?

Two quick answers:

1. Could it?

Depends what you mean by "cable technology like this". I haven't seen Robots, but this kind of constrained, multiple-degree-of-freedom movement would not be possible in an "open world" -- you have to have existing infrastructure, and for something like cables (which "operate" in tension only), that infrastructure has to surround the entire "vehicle". And cables have an effective practical length limit before you run into a number of physics barriers. Now, you could have something that operates by a cable pulling a car along a predefined route, but it would be a simple linear movement. Not only can you, we already do this: most ski lifts work this way. So do, for example, the SF cable cars.

2. Even if you could, should you?

The tl;dr here is that in the vast majority of modern cases, other technology is better. If you're going to expend a whole bunch of money on infrastructure, which is necessary for public transportation in general, why not make it something higher capacity? Lightrail, or high-speed bus, or really almost any other form of public transportation is more effective. Where the ski lift approach shines is in low-volume, low-speed transport across terrain that would be very, very difficult (read: expensive) to lay tracks or road across, like mountains. Similarly, the cable car approach shines in situations where rails offer questionable traction in adverse conditions, and a positive connection with something is hugely beneficial (like a very steep hill). There are always niche applications, but I wouldn't hold my breath for widespread use.

Re: Cable Robot Simulator [video]

#20

Post by Retric »

eatonphil wrote: post #17
vpribish wrote: post #15

Earlier quoted context omitted.

Come visit beautiful San Francisco! https://en.wikipedia.org/wiki/San_Francisco_cable_car_system I think the wires would get in each other's way if you had pods in the same volume.

Ah of course, that was silly of me. I guess I meant suspended cable travel.

Sure: https://en.wikipedia.org/wiki/Ski_lift or https://en.wikipedia.org/wiki/Gondola_lift
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