.. _template-articulated:

Template Articulated
********************************************************************************

This template shows how to simulate an articulated vehicle and plot the results.

In this case, the parameters are defined by the user.

First, we define the Pacejka tire model (:ref:`tire-pacejka`).

.. code-block:: matlab
    
    TireModel = TirePacejka();                      % Choosing tire
    
Then, the tire parameters are defined as

.. code-block:: matlab
    
    TireModel.a0 = 1;
    TireModel.a1 = 2;
    TireModel.a2 = 700;
    TireModel.a3 = 5000;
    TireModel.a4 = 80;
    TireModel.a5 = 0;
    TireModel.a6 = 0;
    TireModel.a7 = 0.6;
    
Check all the tire parameters at :mod:`TirePacejka`.

The nonlinear articulated vehicle model (:ref:`vehicle-articulated-4dof`) is defined as

.. code-block:: matlab
    
    VehicleModel = VehicleArticulatedNonlinear();   % Choosing vehicle
    
The vehicle parameters can be changed as

.. code-block:: matlab
    
    VehicleModel.mF0 = 5200;
    VehicleModel.mR0 = 2400;
    VehicleModel.mF = 6000;
    VehicleModel.mR = 10000;
    VehicleModel.mM = 17000;
    VehicleModel.IT = 46000;
    VehicleModel.IS = 450000;
    VehicleModel.lT = 3.5;
    VehicleModel.lS = 7.7;
    VehicleModel.c = -0.3;
    VehicleModel.nF = 2;
    VehicleModel.nR = 4;
    VehicleModel.nM = 8;
    VehicleModel.wT = 2.6;
    VehicleModel.wS = 2.4;
    VehicleModel.muy = 0.3;
    
Check all the vehicle parameters at :mod:`VehicleSimpleNonlinear`.

The input variables can be defined as

.. code-block:: matlab
    
    VehicleModel.deltaf = 0;
    VehicleModel.Fxf = 0;
    VehicleModel.Fxr = 0;
    VehicleModel.Fxm = 0;
    
When the input variables are defined as a scalar quantity, the attributed value remains the same for the entire simulation span.

The System is completely defined once we attribute the chosen tire model to the vehicle object.

.. code-block:: matlab
    
    VehicleModel.tire = TireModel;
    
Choosing simulation time span

.. code-block:: matlab
    
    T = 7;                              % Total simulation time [s]
    resol = 50;                         % Resolution
    TSPAN = 0:T/resol:T;                % Time span [s]
    
To define a simulation object (:mod:`Simulator`) the arguments must be the vehicle object and the time span.

.. code-block:: matlab
    
    simulator = Simulator(VehicleModel, TSPAN);
    
The default parameters of the simulation object can be found in :mod:`Simulator`. However, we are interested in changing the initial conditions of the simulation object. This can be done running

.. code-block:: matlab
    
    simulator.ALPHAT0 = 0.3;            % Initial tractor side slip angle [rad]
    simulator.dPSI0 = 0.25;             % Initial tractor yaw rate [rad/s]
    simulator.dPHI0 = 0.25;             % Initial articulation rate [rad/s]
    
Now, we have everything needed to run the simulation. For this, we use

.. code-block:: matlab
    
    simulator.Simulate();
    
In this example, the plots of the time response of each state are no presented. For that, see :ref:`template-simple`.

Frame and animation can be generated defining a graphic object (:mod:`Graphics`). The only argument of the graphic object is the simulator object after the simulation.

.. code-block:: matlab
    
    g = Graphics(simulator);
    
To change the color of the tractor and the semitrailer run

.. code-block:: matlab
    
    g.TractorColor = 'r';
    g.SemitrailerColor = 'g';
    
After that, just run

.. code-block:: matlab
    
    g.Frame();
    g.Animation();
    
Both graphics feature can be seen below.

.. figure::  ../illustrations/frame/TemplateArticulatedFrame.svg
    :align:   center
    :width: 60%

    Frame of the articulated vehicle model.

.. figure::  ../illustrations/animation/TemplateArticulatedAnimation.gif
    :align:   center

    Animation of the articulated vehicle model.