This is a simple model of a ground vehicle, comprising the mass, the aerodynamic drag, the rolling resistance and the inclination resistance (caused by the road grade). For all particular resistances, significant variables can be either given by a parameter or input by a time-variable signal.
The vehicle can be driven at the rotational flange
flangeR
, e.g. by an electric motor and a gearbox.
It is possible to use the vehicle as a passive trailer,
leaving the rotational flange flangeR
unconnected.
At the translational flange flangeT
the vehicle can
be coupled with another vehicle, e.g. as a trailer or to pull
a trailer. It is possible to leave the translational flange
flangeT
unconnected.
The velocity v
and the driven
distance s
of the vehicle are provided as
variables; the vehicle can be initialized using these
variables.
Both the translational vehicle mass and the rotational inertias
(e.g. the wheels) are accelerated when the vehicle is accelerated.
This nature is usually put into account for fundamental vehicle
analyses done either in the rotational or translational domain,
e.g. when analysing vehicle's driveline. Then, the vehicle
mass m
can be expressed as an additional
equivalent inertia
J_eq = m * R2
or vice
versa rotational inertia J
as an additional
equivalent mass m_eq = J/R2
,
where R
is the wheel radius. Since this model
introduces rolling resistance and inclination resistance as well
where just the vehicle mass plays a role, the approach of
equivalent mass/inertia would lead to incorrect simulation results
and shall therefore not be applied here.
fDrag = Cd*rho*A*(v - vWind)^2/2
Wind velocity is measured in the same direction as velocity of
flangeT
. Wind velocity is either constant or
prescribed by the input vWind
.
fRoll = Cr*m*g*cos(alpha)
Rolling resistance coefficient Cr is either
constant or prescribed by the input cr
. Rolling
resistance has a crossover from positive to negative velocity
within [-vReg, vReg]
.
The inclination angle α is either constant or
prescribed by the input inclination
=
tan(α). This corresponds to the road rise over running
distance of 100 m which, in general, is written as
a percentage. For example for a road rising by 10 m
over 100 m the grade = 10 % and, thus, the
parameter inclinationConstant = 0.1
.
Positive inclination means driving uphill, negative inclination
means driving downhill, in case of positive vehicle velocity.
fGrav = m*g*sin(alpha)
With the inclination angle α described above.