Tim J.Did you see any information on the Skyweb Express ( www.skywebexpress.com ) 20 vehicle table top PRT scale model. They might be willing to talk about the challenges of building a PRT scale model.Den
Sent: Thursday, August 01, 2013 8:47 PMSubject: [t-i] Why no decent scale models of PRT using off the shelf robots? (Izmir Institute of Technology PRT Demostration project)
Hello,
I came across the Izmir Institute of Technology PRT Demostration project (https://sites.google.com/site/ceng314prt/). When I search YouTube there are plenty of examples of impressive, simple bots (Pololu 3pi Line Maze Solving Robot, http://youtu.be/mJV-KDqHgDQ which sells for US$100 fully assembled.) There are very simple line follower bots. But if you search for "PRT scale model" in YouTube the results are, politely, less than impressive. (The film of the Aerospace Corp. model, from the 1970s(!!), are better than anything else.)After this I wondered to myself why no one has created a decent PRT scale model with a dozen or so small bots running at high speed in a line drawn network using some of these off the shelf bots? I would have thought some of robot aficionados would take it on as a challenge given they wouldn't have to start from scratch as there are so many algorithms and concepts in the public domain.I found some work on other PRT models (http://www.autoroadvehicles.com/downloads/atra-2013-01-13-control-system-bob-johnson-3.pptx) but it was just one vehicle. The discussion of scale model I have seen in this forum from last year seemed to focus on what scale it should be or on recreating the motion control system for one vehicle (https://groups.google.com/forum/#!topicsearchin/transport-innovators/Skytraxprt/transport-innovators/6DDSL1S6C0M).I would have thought the real challenge is the issue of continuous communication between the vehicles and the line side controllers and a central "dispatch" controller. I realise that this is quite complicated to implement so maybe I am expecting too much.Regards,TimDISCLAIMER: I'm a curious (and sceptical) observer of PRT.--
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That doesn’t sound like PRT scale model I’ve seen. Try:Scroll down to Alpha System (page 6)Where is the on-line post you mention. I don’t believe I’ve ever seen it?Dennis
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From: Tim Joy <tje...@gmail.com>
To: transport-...@googlegroups.com
Sent: Friday, August 2, 2013 11:47:17 PM
Subject: Re: [t-i] Why no decent scale models of PRT using off the shelf robots? (Izmir Institute of Technology PRT Demostration project)
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Ever see the video of that old tape by Aerospace Corp? That is more than a good primer on PRT. That model is one very cool toy…There are still thousands of model railroad enthusiasts out there who get great satisfaction building similar stuff, not to mention robot buffs. Could model “railbots” (not to be confused with the game) ever gain a following? After all, a working model of the SMART PRT platform would certainly be equally fun to watch and vehicle avoidance and routing strategies would offer programmers something truly challenging to chew on.
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From: Tim J. <tje...@gmail.com>
To: "transport-...@googlegroups.com" <transport-...@googlegroups.com>
Sent: Sunday, August 4, 2013 12:22:39 AM
Subject: Re: [t-i] Why no decent scale models of PRT using off the shelf robots? (Izmir Institute of Technology PRT Demostration project)
From: Tim J. <tje...@gmail.com>
To: transport-...@googlegroups.com
Sent: Friday, August 2, 2013 2:27:18 AM
Subject: Re: [t-i] Why no decent scale models of PRT using off the shelf robots? (Izmir Institute of Technology PRT Demostration project)
Hi Dennis,It's on their website (on the link you sent me under "Technology") see: http://www.skywebexpress.com/
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I don't think large scale baggage handling is equivalent to a "widescale network" as it exists in a controlled, sympathetic environment and solve the problem of the speed of disembarking by throwing its "passenger" off down a slide without stopping. It's a limited analogue.I should have added the extra condition of widescale URBAN networks. to justify their capital cost would have to operate at, or near, their theoretical capacity. If the origin/destination load is not balanced, it will need to overcome the speed of loading and unloading (larger stations?) and for a system of 100s of vehicles all will need to operate faultlessly.Back on the issue of airport baggage handling I was surprised to read about the failed Denver Airport system that they were BOTH a.warned at the start that it was impossible to achieve (both in the time frame or at all at the time) AND b. that the tug & trolley system could NOT support the requirements. The first proved to be true and the second to be false.
I read some of the Aerospace Corp. review of San Jose and it seemed obvious that the headway of 6 seconds was excessively conservative but I assume this was the best the vendors who replied to the RFI reported to them. Even at half that (still conservative) a network should be able to handle the projected 2030 demand. In that kind of application I would imagine it might be superior. I haven't analysed the alternatives but I think PRT would have to prove itself in just such an installation.Perhaps the Amritsar project will put all of this to the test but I have read that to overcome capacity constraints they plan to have extra guideways.
I suppose part of my reason for posing the question on scale models in this forum in the first place there seemed to be an obvious gap between the (hyperbolic?) claims and the `facts on the ground'.More broadly I always bear in mind that there are significant social and political problems in all forms of transportation for which there are no technological solutions.
I'm sorry if I have gone on so long but I've tried to give a complete answer. I look forward to any replies.Regards,Tim
From: Eric Johnson <itse...@gmail.com>
To: transport-...@googlegroups.com
Sent: Sunday, August 4, 2013 5:22:57 PM
Subject: Re: [t-i] Why no decent scale models of PRT using off the shelf robots? (Izmir Institute of Technology PRT Demostration project)
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Hi Eric,
Is it right to say “Amritsar has steady heavy traffic all day long for some 20 hours a day”? Surely that would be a unique situation, unprecedented in fact. (I don’t know much about the Golden Temple or Sikh rituals so I am willing to concede that it may be the case).
Also you say “Station capacity & design seems to be the main issue to handle that many people.“ Isn’t that the million dollar question for PRT? The real constraint is in the stations. (Not a unique problem to PRT). I think I read somewhere that the Amritsar plan is to duplicate the guideways in some areas to add capacity.
If you say “The only thing needed to make a new PRT functional is a test track program to verify integration & operations“ does that mean CabinTaxi, ULTra and Vectus have NOT shown PRT is functional? (Excuse my ignorance but I am guessing you have a different design).
You said:
Amritsar has steady heavy traffic all day long for some 20 hours a day. There system can handle 50,000 people per day per direction since they are looking to pack each pod with 6 people. If we assume they average 5 people per pod and 6 second headways that's 3000 people per hour per direction or some 60,000 people per day. Station capacity & design seems to be the main issue to handle that many people.
We base our claims on what PRT can do on simple math (headway * pax per pod, station throughput, speeds, etc) and that we've had several PRT test systems that have separately proven the concepts with different software & hardware. Guideway construction, vehicle design & construction, station construction, vehicle communications, etc are well known. We can use existing software or write new programs to meet our needs. The only thing needed to make a new PRT functional is a test track program to verify integration & operations.
From: transport-...@googlegroups.com [mailto:transport-...@googlegroups.com] On Behalf Of Eric Johnson
Sent: Monday, August 05, 2013 12:57 AM
To: transport-...@googlegroups.com
Subject: Re: [t-i] Why no decent scale models of PRT using off the shelf robots? (Izmir Institute of Technology PRT Demostration project)
Tim,
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Hi Eric,
I’ll have to study your spreadsheet to get a better feel for it. It’s impressive with a lot of information.
After an initial view the first thing that comes to mind is I would have thought elevated stations would cost more than your calculations would indicate. Have you compared these costs with any similar structures?
Tim
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From: transport-...@googlegroups.com [mailto:transport-...@googlegroups.com] On Behalf Of Eric Johnson
Sent: Monday, August 05, 2013 12:57 AM
To: transport-...@googlegroups.com
Subject: Re: [t-i] Why no decent scale models of PRT using off the shelf robots? (Izmir Institute of Technology PRT Demostration project)
Tim,
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