Within the Simulink® environment, you follow best practice if you model driveline systems by representing as much of the physical system as possible with Simscape™ Driveline™ and Simscape components. Major advantages include these features that make it easier to create accurate simulations of physical systems:
Physical ports and connection lines supporting physical units
Consistent treatment of differential and algebraic constraint equations
Customization with Simscape Foundation blocks and Simscape language
For custom block modeling with Simscape language, see Custom Components (Simscape).
Reserve Simulink blocks and signals for nonphysical aspects of modeling, such as nonphysical signals, algorithmic control, and model-level input/output tasks.
Simscape Driveline and Simscape physical connections help you create model architectures with clear physical component boundaries. You can then increase the fidelity of the model overall, or make only certain components more accurate representations of the system.
In driveline modeling, there are several reasons for making a model more complex and accurate.
Driveline models abstract the motion of three-dimensional mechanical systems constrained to move in one dimension. Some driveline components require extra specification to capture underlying two- and three-dimensional geometry. An example in the Simscape Driveline library is the Differential gear.
Many standard Simscape Driveline components allow you to enable or disable modeling of internal dynamics. For example, Generic Engine allows you to represent an engine with instantaneous response for a simple, idealized model. To access a more complex and accurate representation, enable the internal time lag for the Generic Engine block. You can also create your own custom components (with internal compliance dynamics, for example), to whatever degree of fidelity and complexity that you want.
Much of complex internal dynamic Simscape Driveline modeling comes from representing the effect of both viscous and Coulomb friction.
Viscous friction is proportional to the relative velocity of two surfaces in contact.
Coulomb, or “sliding-sticky,” friction is proportional to the force normal to surfaces in contact. For low relative velocities, Coulomb friction causes surfaces to lock and cease relative motion.
Thus, friction models involve specification of relative geometry and motion, friction coefficients, and normal forces, of surfaces in contact.
Components with internal friction models include gears, clutches, tires, and other couplings, at different levels of optional complexity.
Typically, greater fidelity of model components results in reduced simulation performance and changes the tradeoff between simulation accuracy and speed. You can adapt your simulation methods to handle greater fidelity, or reduce model fidelity to enhance performance.