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article - delta engineering

From Phenomena to Chrono - how far away is Chrono now?

Alessandro Tasora kindly allowed us to "interview" him on the 2nd December 2002. This is the full transcript from the conversation:

B: Alessandro, tell us a little about yourself:

A: I work at the university as a researcher, so I have time to develop software about topics I like most (expecially for 3D graphics), either at the university and at home.
I also teach mechanical design, robotics and automation at the local university: that's why I am interested in computer simulation of physical phenomena. In fact I decided that I would have developed my own simulation code
instead of using third party software: that's why I decided to develop Chrono.

B: You wrote a very sucessful plugin for Real 3D v3 - called Phenomena. Do you have any thoughts about releasing it for v4 ?

A: I would like, but I have no time for that project, even if the user were very happy and the feedback was very positive.
Anyway I know that other plugin developers are working on similar plugins, for v4.

B: What is Chrono ?

A: Chrono is a plugin for multibody simulation. In detail, it can simulate the behaviour of mechanical systems of whatever kind.
For example, you can build a car, made of articulated suspensions, springs, engines, etc., then you turn on the engine and you can drive it. Dynamical effects are computed realistically, not mocked-up as in videogames.
You can use it also to simulate automatic devices, robots, walking machines, skeletons for character animation, etc.

B: Chrono has been your development baby now for a number of years - why does it take so long to develop ? Did you set your goals too high to start with ?

A: In fact Chrono was almost complete more than one year ago, but as time passed, the more I had to implement new features (and this continuously postponed the writing of the manual and the last refinements). This month I decided to dive into the manual, because too much people is asking it, so I wrote 90% of the reference manual with a new publishing tool. In fact one of the major causes of delays of Chrono was the fact that I was using word-processing sw for manual & help files (now I use the PdfLatex compiler, which is hard to learn at the beginnning but allow you to keep your documentation updated with less efforts, since it makes Pdf and hypertext at once).
If I had set a simplier goal, of course I would have finished the developement way before. Chrono started as a tool for simple mechanism simulation, but here at the university we are already using it for complex design tasks, so it often happens that some coworker of mine asks new feature for some specific job, etc.
By the way, implementing multibody simulation code maybe one of the hardest tasks for a scientist/programmer!

click to enlarge

B: How is Chrono coming along ? Any ideas on a release date as yet ?

A: Chrono is enough usable for whatever 'average' user of Realsoft, since I made the interface of its tools as intuitive as possible.
There are, anyway, many hi-end features which I would like to document better, and to make them more usable (for example the tool which studies the working area of robots, etc.)

B: Would development of your plugins be easier if the RS community helped ? (eg manuals / testing etc ?)

A: I guess that I could ask some help in manual proofreading, since I'm writing it very fast, without paying too attention
to the syntax...

click to enlarge

B: I understand that you use Chrono yourself for a number of real-world applications - care to tell us about any of those ?

A: Yes, the fact that we used Chrono in many real world applications is the major cause of delay, as I told you before, but this also means that it works very well, since the correctness and the power of its simulation engine has been tested with engineering applications.

Some examples:

  • we designed and built a robot prototype (name: "Sloth") which is one of the fastest pick-and-place robots ever existed. Chrono allowed us to simulate inertial effects, kinematics, working area, optimizations, motor choice, etc., before the robot was built.
  • in the same way, we designed, builted and tested an innovative pneumatic robot (name: "Torx").
  • similarly, we are developing a 6-dof parallel robot for fast milling, with innovative kinematics.
  • we designed a prosthetic shoulder which has two motorized degrees of freedom, using an inverse Cardano joint. Here
    we used Chrono to choose the best solution among many ideas. A prototype has been built.
  • we studied the effect of road unevenness on bicycle ride, for a research on road safety. This was a very complex set of 200+ simulations.
  • we are designing a car-simulator (suspended on actuators like the Jumbo simulators) and we are including the Chrono simulation kernel into the real-time DirectX visualization, for the virtual-reality display.
  • we are simulating a pneumatic hand, and much more...

B: Who is Chrono aimed at ? The casual user or the engineer / designer looking for accurate data / output ?

A: When we started, we had a lower profile in mind, but now we see that it is more targeted to the high-end user. Expecially because we are stressing the features which allow the introduction of digital controls, etc. to simulate PLC, robots, automatic devices, AI.
A low cost version will be available anyway, simply without data plotting features.

B: Do you have any ideas for future plugins ?

A: Yes, of course. Since Chrono become more and more serious, we see that there's the opportunity to push it on the
mechanical-engineering market. To do this, it would be better to have also another plugin, which turns Realsoft into a 3D-CAD modeler (with better support of nurb trimming, variational and parametric dimensioning, vectorial outline output). That's why I am studying how to port OpenCascade to Realsoft with a new plugin (see to see what I mean). This would be useful for architects, not only for engineers and designers... And OpenCascade is open-source.

click to find out more on OpenCascade

B: You know the team at Realsoft fairly well by now - do they look after you in terms of development / support ? Is there anything further you would want from Realsoft ?

A: Realsoft support is great!

B: Why write plugins for Realsoft 3D ? Comments / hints to any would-be Realsoft developers ?

A: Because the architecture of Realsoft is open, flexible and intelligent. (The only problem may be that the API is based on tag-dispatcher OOP methods which are a bit hard to learn at the beginning).

B: Version 4.5 - how has it impacted on your development ? Has Javascript support helped you now ?

A: Chrono was meant to be Javascript-compliant even before v4.5. The RS team works very well because they listen to all requests from plugin developers.

click to enlarge

B: Realsoft 3D is obviously a backbone to your plugins - are you happy with the latest version ?

A: Yes, of course.

B: Looking back in retrospect - how would you have changed things (if anything) when developing Chrono.

A: I would have included less features :-) And I would have not wasted time writing the manual with a famous word processor, which did not prove to be the best way to go... ;-)

B: So what does the future hold for you ? Do you have any long term plans in where you would like to see RS head ?

A: As soon as Chrono is finished, I'll try to port the OpenCascade geometric kernel to RS. This would be useful also
for my own design jobs.

B: And finally, is there anything you wish to say to the RS community ?

A: A great community, really!

Alessandro, many thanks for taking the time out to complete these questions ! We all wish you the best of luck with the plugin and look forward eagerly for its release.


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Page updated on Friday, 28 February, 2003 . For feedback / model submissions or articles - please email us.
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