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...