Gear trains and complex gear systems inside Inventor

A gear train is a set of gears arranged to transfer rotational torque from one part of a mechanical system to another.

If these are combined in articulated structures with multiple degrees of freedom (DOF), the resulting composite is a very complex to analyze and simulate physical system.

Inventor physics emulation engine is going to have a module (still under intensive development), to analytically solve and simulate such these complex systems. Moreover, each one of these independent gear systems will have to interact correctly between them, and with the rest of particle based systems (fluids, strings, springs, ...)

If this could be achieved, much more interesting and challenging levels would be available in Inventor. The achievement of this development, also brings the possibility to include engines and dynamos (perhaps adding electric circuits to simulation), hydraulic cylinders, ...


Algorithm


As said before, gear systems will be solved inside Inventor engine analytically. A previous one-week effort was done some months ago to solve this issue. In this first attempt, gears were treated like the rest of the particles in the engine. The system was not analyzed at all, and contiguous gear interactions were solved independently. That was fine for the simplest gear systems, but with gear reductions and articulated structures, the engine became highly unstable (Inventor implements a very low level fixed-point engine).

Gear train in articulated structure

In this new review, the engine will try to "understand" the system, extracting its degrees of freedom and constituting elements relations. This is better understood with an example. Take in mind the system of the game snapshot shown in the right. Note that the eight-teeth brown gears, are integral with the structures they are joined to (that is, they cannot turn independently from their joining structure). That means that the lower 48-teeth brown gear cannot turn, and that the other 48-teeth brown gear will also maintain its angle, and therefore, the pink structure will always be vertical, even when the yellow central structure turns. But what's more, the lower 24/8-teeth blue gear will turn 18 times faster than the yellow structure, increasing the system momentum, and making the whole structure to move slowly. In spite of the apparent complexity of this example, it has a single degree of freedom.

As long as this algorithm is implemented and working, it will be explained here...

Learning with Inventor

The main idea behind Inventor is to learn physics (and other science areas). Knowledge levels will be rewarded progressively when achieving challenge ones. And also, assimilating knowledge subjects will ease the resolution of the challenges.

Last hours of development have been devoted to functional plots. Multi-set y=f(x) and XY-plots are now possible. To test the new sub-system, the following knowledge level has been created to explain the effect of gravitation near planets surface:



Knowledge levels are interactive. This one is rather simple, basically, only time scale and planet/moon can be changed to evaluate the effects of gravitation. The sets of y=f(t, g) are the parabolas that a weight describes in the surfaces of the planets of the Solar System.

Some other knowledge levels I would like to implement are: bounce in elastic objects, collision between objects, string tension analysis, friction, Newton's three laws of motion, inertia, moment of inertia, ...

Stay tuned!

Sample video

Here it is the first Inventor sample video. It shows main menu navigation, in-game tool bar, basic usage and the resolution of a pulley system challenge of medium complexity.

Inventor is designed for touch screen devices (currently implemented and tested under Android and Bada systems). Touch screen effect is shown in the sample video with white rings over the pulsation position that do not appear in real game.

Some actions shown in the video:

• Opening and closing tool bars.
• Long pulsation over scene or tool bar elements, show their physical properties.
• Double tap while in challenge mode, stops/starts simulation.
• Drag and drop from tool bar to scene.
• String/rope arranging.
• Slow motion and challenge tips.

In the following posts, some features of this unique (as long as I know) physics engine will be revealed.

Presentation

Inventor is a brain game / educational application that implements an extensible real-time physics simulation engine. Unlike other physical engines, it's designed to support, not only rigid objects, but elastic interactions, strings, springs, gears, fluids, ...

Unique simulations inside inventor are physically correct in the sense that complex pulley systems, gear chains and the rest of elements, behave exactly like in real life. For instance, measuring string tension, in stationary state of a complex pulley system, will give you the theoretical value.

I'll try to add some sample videos soon!