Vamos Automotive Simulator git

//  Drivetrain.cc - manages the engine, clutch, transmission and differential.
//
//  Copyright (C) 2001--2002 Sam Varner
//
//  This file is part of Vamos Automotive Simulator.
//
//  Vamos is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  Vamos is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with Vamos.  If not, see <http://www.gnu.org/licenses/>.

#include "Drivetrain.hpp"

#include <cassert>

using namespace Vamos_Body;

Drivetrain::Drivetrain(Engine *engine, Clutch *clutch, Transmission *transmission,
                       Differential *differential)
    : mp_engine(engine),
      mp_clutch(clutch),
      mp_transmission(transmission),
      mp_differential(differential)
{
    assert(mp_engine && mp_clutch && mp_transmission && mp_differential);
}

void Drivetrain::input(double gas, double clutch, double left_wheel_speed, double right_wheel_speed)
{
    m_gas = gas;
    mp_clutch->position(clutch);

    double shaft_speed = mp_differential->get_driveshaft_speed(left_wheel_speed, right_wheel_speed);
    mp_transmission->set_driveshaft_speed(shaft_speed);
    if (m_auto_neutral && mp_engine->rotational_speed() == 0.0 && !mp_engine->is_out_of_gas())
    {
        mp_transmission->shift(0);
        mp_engine->start();
    }
}

void Drivetrain::propagate(double time)
{
    // Find the drag due to friction in the clutch if the clutch is not fully engaged, and
    // the torque on the driveshaft.
    double drag = 0.0;
    double torque = 0.0;
    double clutch_speed = 0.0;
    bool engaged = mp_transmission->get_gear() != 0 && mp_clutch->engaged();

    if (engaged)
    {
        // If the clutch is fully engaged, the engine speed is forced to match the
        // transmission speed.  There is no clutch drag.
        clutch_speed = mp_transmission->get_clutch_speed();
        torque = mp_transmission->get_torque(mp_engine->drive_torque());
    }
    else if (mp_transmission->get_gear() != 0)
    {
        // Find the drag due to friction in the clutch.  As a side-effect, the value
        // of Clutch::engaged() is set.
        drag = mp_clutch->drag(mp_engine->rotational_speed(), mp_transmission->get_clutch_speed());
        // Find out how much torque we get from the drivetrain.
        torque = mp_transmission->get_torque(drag);
    }

    mp_engine->input(m_gas, drag, clutch_speed, engaged);
    // Apply the torque to the differential.
    mp_differential->find_wheel_torques(torque);
    mp_engine->propagate(time);
}

void Drivetrain::reset()
{
    mp_clutch->position(0.0);
    mp_transmission->shift(0);
}

double Drivetrain::torque(Vamos_Geometry::Direction side) const
{
    switch (side)
    {
    case Vamos_Geometry::LEFT:
        return mp_differential->left_wheel_torque();
    case Vamos_Geometry::RIGHT:
        return mp_differential->right_wheel_torque();
    default:
        assert(false);
        break;
    }
    return 0.0;
}