Coupling of Activate - MotionSolve - EDEM software for an accurate simulation of a Tractor on soil.
Problem Setting:
For an accurate simulation of complex real world systems, the use of a single simulation tool is often not enough. In this example we combine Activate - MotionSolve and EDEM in order to produce a realistic behavior of a tractor harrowing soil.
We can split this problem into 3 distinct tasks:
1) The creation of a realistic soil model.
2) The creation of a multibody model which contains the tractor and it's equipment.
3) The creation of appropriate controllers for the traction and the steering of the vehicle.
It becomes clear that we have to solve a multiphysics problem. To address that we can use Altair's specialized tools for each of the tasks.
EDEM:
Starting on Altair EDEM, discrete element method (DEM) software, we can make use of it's library of predefined soil starter packs, which are models based and validated by measurements. For the final granular material simulation, over 200.000 distinct particles, accurately interacted with each other and with the tractor's tires and equipment.
MotionSolve :
Moving on to the multibody system simulation model for the tractor, we can import our CAD and create appropriate Joints and motions, to connect the different bodies and lower the equipment of the tractor using Altair MotionSolve.
Activate :
Lastly, we need a traction controller for the driving wheels of the vehicle, to quickly and smoothly reach the desired vehicle velocity and maintain it, as well as a steering controller, to keep the vehicle on a straight path due to disturbances. For this we need to use multi-disciplinary system simulation software - Altair Activate.
Coupling :
We now have to connect all three, different simulation tools we used, in order to produce a single coupled simulation of the multiphysics model. There are 2 paths we can take to achieve this.
1. Activate - MotionSolve - EDEM coupling :
The first path, is to use Activate as the leading (main) solver. The multibody model alongside the soil model will be imported as Co-Simulation FMU's inside Activate.
2. MotionSolve - Activate - EDEM coupling :
The second path, is to use MotionSolve as the leading (main) solver. The activate model for the controllers can be imported as a Model Exchange or Co-Simulation FMU inside MotionSolve. MotionSolve will also co-simulate with EDEM in order to produce the final coupled simulation.
How to choose between the 2 options?
Both options are valid and will produce very similar results. The use of one option in favor of another boils down to the main focus of the simulation.
When we are trying to optimize the controllers, working from Activate is easier as we can make changes and run the simulation from the same environment.
If the interest of the simulation is not on the controllers, but on analyzing the multibody result, then using MotionSolve and MotionView's environment will enable us to quickly analyze those results and run subsequent simulations.
Conclusions :
Altair provides specialized tools for different simulations, but it also provides an easy and user-friendly way to combine those tools in order to model and simulate complex systems.
Below, you can watch a quick video detailing the above case.