VehicleBase.cpp

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/*+-------------------------------------------------------------------------+
  |                       MultiVehicle simulator (libmvsim)                 |
  |                                                                         |
  | Copyright (C) 2014  Jose Luis Blanco Claraco (University of Almeria)    |
  | Copyright (C) 2017  Borys Tymchenko (Odessa Polytechnic University)     |
  | Distributed under GNU General Public License version 3                  |
  |   See <http://www.gnu.org/licenses/>                                    |
  +-------------------------------------------------------------------------+ */

#include <mvsim/World.h>
#include <mvsim/VehicleBase.h>
#include <mvsim/VehicleDynamics/VehicleAckermann.h>
#include <mvsim/VehicleDynamics/VehicleAckermann_Drivetrain.h>
#include <mvsim/VehicleDynamics/VehicleDifferential.h>
#include <mvsim/FrictionModels/FrictionBase.h>
#include <mvsim/FrictionModels/DefaultFriction.h>  // For use as default model

#include "JointXMLnode.h"
#include "XMLClassesRegistry.h"
#include "xml_utils.h"

#include <rapidxml.hpp>
#include <rapidxml_utils.hpp>
#include <rapidxml_print.hpp>
#include <mrpt/poses/CPose2D.h>
#include <mrpt/opengl/CPolyhedron.h>

#include <sstream>  // std::stringstream
#include <map>
#include <string>

using namespace mvsim;
using namespace std;

XmlClassesRegistry veh_classes_registry("vehicle:class");

TClassFactory_vehicleDynamics mvsim::classFactory_vehicleDynamics;

// Explicit registration calls seem to be one (the unique?) way to assure
// registration takes place:
void register_all_veh_dynamics()
{
        static bool done = false;
        if (done)
                return;
        else
                done = true;

        REGISTER_VEHICLE_DYNAMICS("differential", DynamicsDifferential)
        REGISTER_VEHICLE_DYNAMICS("ackermann", DynamicsAckermann)
        REGISTER_VEHICLE_DYNAMICS(
                "ackermann_drivetrain", DynamicsAckermannDrivetrain)
}

constexpr char VehicleBase::DL_TIMESTAMP[];
constexpr char VehicleBase::LOGGER_POSE[];
constexpr char VehicleBase::LOGGER_WHEEL[];

constexpr char VehicleBase::PL_Q_X[];
constexpr char VehicleBase::PL_Q_Y[];
constexpr char VehicleBase::PL_Q_Z[];
constexpr char VehicleBase::PL_Q_YAW[];
constexpr char VehicleBase::PL_Q_PITCH[];
constexpr char VehicleBase::PL_Q_ROLL[];
constexpr char VehicleBase::PL_DQ_X[];
constexpr char VehicleBase::PL_DQ_Y[];
constexpr char VehicleBase::PL_DQ_Z[];

constexpr char VehicleBase::WL_TORQUE[];
constexpr char VehicleBase::WL_WEIGHT[];
constexpr char VehicleBase::WL_VEL_X[];
constexpr char VehicleBase::WL_VEL_Y[];
constexpr char VehicleBase::WL_FRIC_X[];
constexpr char VehicleBase::WL_FRIC_Y[];

// Protected ctor:
VehicleBase::VehicleBase(World* parent, size_t nWheels)
        : VisualObject(parent),
          m_vehicle_index(0),
          m_b2d_vehicle_body(NULL),
          m_q(0, 0, 0, 0, 0, 0),
          m_dq(0, 0, 0),
          m_chassis_mass(15.0),
          m_chassis_z_min(0.05),
          m_chassis_z_max(0.6),
          m_chassis_color(0xff, 0x00, 0x00),
          m_chassis_com(.0, .0),
          m_wheels_info(nWheels),
          m_fixture_wheels(nWheels, NULL)
{
        using namespace mrpt::math;
        // Default shape:
        m_chassis_poly.push_back(TPoint2D(-0.4, -0.5));
        m_chassis_poly.push_back(TPoint2D(-0.4, 0.5));
        m_chassis_poly.push_back(TPoint2D(0.4, 0.5));
        m_chassis_poly.push_back(TPoint2D(0.6, 0.3));
        m_chassis_poly.push_back(TPoint2D(0.6, -0.3));
        m_chassis_poly.push_back(TPoint2D(0.4, -0.5));
        updateMaxRadiusFromPoly();
}

void VehicleBase::simul_post_timestep_common(const TSimulContext& context)
{
        if (m_b2d_vehicle_body)
        {
                // Pos:
                const b2Vec2& pos = m_b2d_vehicle_body->GetPosition();
                const float32 angle = m_b2d_vehicle_body->GetAngle();
                m_q.x = pos(0);
                m_q.y = pos(1);
                m_q.yaw = angle;
                // The rest (z,pitch,roll) will be always 0, unless other world-element
                // modifies them! (e.g. elevation map)

                // Vel:
                const b2Vec2& vel = m_b2d_vehicle_body->GetLinearVelocity();
                const float32 w = m_b2d_vehicle_body->GetAngularVelocity();
                m_dq.vals[0] = vel(0);
                m_dq.vals[1] = vel(1);
                m_dq.vals[2] = w;
        }
}

void VehicleBase::register_vehicle_class(
        const rapidxml::xml_node<char>* xml_node)
{
        // Sanity checks:
        if (!xml_node)
                throw runtime_error(
                        "[VehicleBase::register_vehicle_class] XML node is NULL");
        if (0 != strcmp(xml_node->name(), "vehicle:class"))
                throw runtime_error(
                        mrpt::format(
                                "[VehicleBase::register_vehicle_class] XML element is '%s' "
                                "('vehicle:class' expected)",
                                xml_node->name()));

        // rapidxml doesn't allow making copied of objects.
        // So: convert to txt; then re-parse.
        std::stringstream ss;
        ss << *xml_node;

        veh_classes_registry.add(ss.str());
}

VehicleBase* VehicleBase::factory(
        World* parent, const rapidxml::xml_node<char>* root)
{
        register_all_veh_dynamics();

        using namespace std;
        using namespace rapidxml;

        if (!root) throw runtime_error("[VehicleBase::factory] XML node is NULL");
        if (0 != strcmp(root->name(), "vehicle"))
                throw runtime_error(
                        mrpt::format(
                                "[VehicleBase::factory] XML root element is '%s' ('vehicle' "
                                "expected)",
                                root->name()));

        // "class": When a vehicle has a 'class="XXX"' attribute, look for each
        // parameter
        //  in the set of "root" + "class_root" XML nodes:
        // --------------------------------------------------------------------------------
        JointXMLnode<> veh_root_node;
        {
                veh_root_node.add(
                        root);  // Always search in root. Also in the class root, if any:

                const xml_attribute<>* veh_class = root->first_attribute("class");
                if (veh_class)
                {
                        const string sClassName = veh_class->value();
                        const rapidxml::xml_node<char>* class_root =
                                veh_classes_registry.get(sClassName);
                        if (!class_root)
                                throw runtime_error(
                                        mrpt::format(
                                                "[VehicleBase::factory] Vehicle class '%s' undefined",
                                                sClassName.c_str()));

                        veh_root_node.add(class_root);
                        // cout << *class_root;
                }
        }

        // Class factory according to: <dynamics class="XXX">
        // -------------------------------------------------
        const xml_node<>* dyn_node = veh_root_node.first_node("dynamics");
        if (!dyn_node)
                throw runtime_error(
                        "[VehicleBase::factory] Missing XML node <dynamics>");

        const xml_attribute<>* dyn_class = dyn_node->first_attribute("class");
        if (!dyn_class || !dyn_class->value())
                throw runtime_error(
                        "[VehicleBase::factory] Missing mandatory attribute 'class' in "
                        "node <dynamics>");

        VehicleBase* veh =
                classFactory_vehicleDynamics.create(dyn_class->value(), parent);
        if (!veh)
                throw runtime_error(
                        mrpt::format(
                                "[VehicleBase::factory] Unknown vehicle dynamics class '%s'",
                                dyn_class->value()));

        // Initialize here all common params shared by any polymorphic class:
        // -------------------------------------------------
        // attrib: name
        {
                const xml_attribute<>* attrib_name = root->first_attribute("name");
                if (attrib_name && attrib_name->value())
                {
                        veh->m_name = attrib_name->value();
                }
                else
                {
                        // Default name:
                        static int cnt = 0;
                        veh->m_name = mrpt::format("veh%i", ++cnt);
                }
        }

        // (Mandatory) initial pose:
        {
                const xml_node<>* node = veh_root_node.first_node("init_pose");
                if (!node)
                        throw runtime_error(
                                "[VehicleBase::factory] Missing XML node <init_pose>");

                if (3 != ::sscanf(
                                         node->value(), "%lf %lf %lf", &veh->m_q.x, &veh->m_q.y,
                                         &veh->m_q.yaw))
                        throw runtime_error(
                                "[VehicleBase::factory] Error parsing "
                                "<init_pose>...</init_pose>");
                veh->m_q.yaw *= M_PI / 180.0;  // deg->rad
        }

        // (Optional) initial vel:
        {
                const xml_node<>* node = veh_root_node.first_node("init_vel");
                if (node)
                {
                        if (3 != ::sscanf(
                                                 node->value(), "%lf %lf %lf", &veh->m_dq.vals[0],
                                                 &veh->m_dq.vals[1], &veh->m_dq.vals[2]))
                                throw runtime_error(
                                        "[VehicleBase::factory] Error parsing "
                                        "<init_vel>...</init_vel>");
                        veh->m_dq.vals[2] *= M_PI / 180.0;  // deg->rad

                        // Convert twist (velocity) from local -> global coords:
                        const mrpt::poses::CPose2D pose(
                                0, 0, veh->m_q.yaw);  // Only the rotation
                        pose.composePoint(
                                veh->m_dq.vals[0], veh->m_dq.vals[1], veh->m_dq.vals[0],
                                veh->m_dq.vals[1]);
                }
        }

        // Initialize class-specific params:
        // -------------------------------------------------
        veh->dynamics_load_params_from_xml(dyn_node);

        // <Optional> Log path. If not specified, app folder will be used
        // -----------------------------------------------------------
        {
                const xml_node<>* log_path_node = veh_root_node.first_node("log_path");
                if (log_path_node)
                {
                        // Parse:
                        veh->m_log_path = log_path_node->value();
                }
        }

        veh->initLoggers();

        // Register bodies, fixtures, etc. in Box2D simulator:
        // ----------------------------------------------------
        b2World* b2world = parent->getBox2DWorld();
        veh->create_multibody_system(b2world);

        if (veh->m_b2d_vehicle_body)
        {
                // Init pos:
                veh->m_b2d_vehicle_body->SetTransform(
                        b2Vec2(veh->m_q.x, veh->m_q.y), veh->m_q.yaw);
                // Init vel:
                veh->m_b2d_vehicle_body->SetLinearVelocity(
                        b2Vec2(veh->m_dq.vals[0], veh->m_dq.vals[1]));
                veh->m_b2d_vehicle_body->SetAngularVelocity(veh->m_dq.vals[2]);
        }

        // Friction model:
        // Parse <friction> node, or assume default linear model:
        // -----------------------------------------------------------
        {
                const xml_node<>* frict_node = veh_root_node.first_node("friction");
                if (!frict_node)
                {
                        // Default:
                        veh->m_friction = std::shared_ptr<FrictionBase>(
                                new DefaultFriction(*veh, NULL /*default params*/));
                }
                else
                {
                        // Parse:
                        veh->m_friction = std::shared_ptr<FrictionBase>(
                                FrictionBase::factory(*veh, frict_node));
                        ASSERT_(veh->m_friction);
                }
        }

        // Sensors: <sensor class='XXX'> entries
        // -------------------------------------------------
        for (JointXMLnode<>::iterator it = veh_root_node.begin();
                 it != veh_root_node.end(); ++it)
        {
                if (!strcmp(it->name(), "sensor"))
                {
                        SensorBase* se = SensorBase::factory(*veh, *it);
                        veh->m_sensors.push_back(SensorBase::Ptr(se));
                }
        }

        return veh;
}

VehicleBase* VehicleBase::factory(World* parent, const std::string& xml_text)
{
        // Parse the string as if it was an XML file:
        std::stringstream s;
        s.str(xml_text);

        char* input_str = const_cast<char*>(xml_text.c_str());
        rapidxml::xml_document<> xml;
        try
        {
                xml.parse<0>(input_str);
        }
        catch (rapidxml::parse_error& e)
        {
                unsigned int line =
                        static_cast<long>(std::count(input_str, e.where<char>(), '\n') + 1);
                throw std::runtime_error(
                        mrpt::format(
                                "[VehicleBase::factory] XML parse error (Line %u): %s",
                                static_cast<unsigned>(line), e.what()));
        }
        return VehicleBase::factory(parent, xml.first_node());
}

void VehicleBase::simul_pre_timestep(const TSimulContext& context)
{
        // Update wheels position (they may turn, etc. as in an Ackermann
        // configuration)
        for (size_t i = 0; i < m_fixture_wheels.size(); i++)
        {
                b2PolygonShape* wheelShape =
                        dynamic_cast<b2PolygonShape*>(m_fixture_wheels[i]->GetShape());
                wheelShape->SetAsBox(
                        m_wheels_info[i].diameter * 0.5, m_wheels_info[i].width * 0.5,
                        b2Vec2(m_wheels_info[i].x, m_wheels_info[i].y),
                        m_wheels_info[i].yaw);
        }

        // Apply motor forces/torques:
        this->invoke_motor_controllers(context, m_torque_per_wheel);

        // Apply friction model at each wheel:
        const size_t nW = getNumWheels();
        ASSERT_EQUAL_(m_torque_per_wheel.size(), nW);

        const double gravity = getWorldObject()->get_gravity();
        const double massPerWheel =
                getChassisMass() / nW;  // Part of the vehicle weight on each wheel.
        const double weightPerWheel = massPerWheel * gravity;

        std::vector<mrpt::math::TPoint2D> wheels_vels;
        getWheelsVelocityLocal(wheels_vels, getVelocityLocal());

        ASSERT_EQUAL_(wheels_vels.size(), nW);

        std::vector<mrpt::math::TSegment3D>
                force_vectors;  // For visualization only

        for (size_t i = 0; i < nW; i++)
        {
                // prepare data:
                Wheel& w = getWheelInfo(i);

                FrictionBase::TFrictionInput fi(context, w);
                fi.motor_torque =
                        -m_torque_per_wheel[i];  // "-" => Forwards is negative
                fi.weight = weightPerWheel;
                fi.wheel_speed = wheels_vels[i];

                m_friction->setLogger(
                        getLoggerPtr(LOGGER_WHEEL + std::to_string(i + 1)));
                // eval friction:
                mrpt::math::TPoint2D net_force_;
                m_friction->evaluate_friction(fi, net_force_);

                // Apply force:
                const b2Vec2 wForce = m_b2d_vehicle_body->GetWorldVector(
                        b2Vec2(
                                net_force_.x, net_force_.y));  // Force vector -> world coords
                const b2Vec2 wPt = m_b2d_vehicle_body->GetWorldPoint(
                        b2Vec2(w.x, w.y));  // Application point -> world coords
                // printf("w%i: Lx=%6.3f Ly=%6.3f  | Gx=%11.9f
                // Gy=%11.9f\n",(int)i,net_force_.x,net_force_.y,wForce.x,wForce.y);

                m_b2d_vehicle_body->ApplyForce(wForce, wPt, true /*wake up*/);

                // log
                {
                        m_loggers[LOGGER_WHEEL + std::to_string(i + 1)]->updateColumn(
                                DL_TIMESTAMP, context.simul_time);
                        m_loggers[LOGGER_WHEEL + std::to_string(i + 1)]->updateColumn(
                                WL_TORQUE, fi.motor_torque);
                        m_loggers[LOGGER_WHEEL + std::to_string(i + 1)]->updateColumn(
                                WL_WEIGHT, fi.weight);
                        m_loggers[LOGGER_WHEEL + std::to_string(i + 1)]->updateColumn(
                                WL_VEL_X, fi.wheel_speed.x);
                        m_loggers[LOGGER_WHEEL + std::to_string(i + 1)]->updateColumn(
                                WL_VEL_Y, fi.wheel_speed.y);
                        m_loggers[LOGGER_WHEEL + std::to_string(i + 1)]->updateColumn(
                                WL_FRIC_X, net_force_.x);
                        m_loggers[LOGGER_WHEEL + std::to_string(i + 1)]->updateColumn(
                                WL_FRIC_Y, net_force_.y);
                }

                // save it for optional rendering:
                if (m_world->m_gui_options.show_forces)
                {
                        const double forceScale =
                                m_world->m_gui_options.force_scale;  // [meters/N]
                        const mrpt::math::TPoint3D pt1(
                                wPt.x, wPt.y, m_chassis_z_max * 1.1 + m_q.z);
                        const mrpt::math::TPoint3D pt2 =
                                pt1 + mrpt::math::TPoint3D(wForce.x, wForce.y, 0) * forceScale;
                        force_vectors.push_back(mrpt::math::TSegment3D(pt1, pt2));
                }
        }

        // Save forces for optional rendering:
        if (m_world->m_gui_options.show_forces)
        {
                std::lock_guard<std::mutex> csl(m_force_segments_for_rendering_cs);
                m_force_segments_for_rendering = force_vectors;
        }
}

void VehicleBase::simul_post_timestep(const TSimulContext& context)
{
        // Integrate wheels' rotation:
        const size_t nW = getNumWheels();

        for (size_t i = 0; i < nW; i++)
        {
                // prepare data:
                Wheel& w = getWheelInfo(i);

                // Explicit Euler:
                w.setPhi(w.getPhi() + w.getW() * context.dt);

                // Wrap wheel spin position (angle), so it doesn't
                // become excessively large (it's actually unbound, but we don't want to
                // lose 'double' accuracy):
                const double cur_abs_phi = std::abs(w.getPhi());
                if (cur_abs_phi > 1e4)
                        w.setPhi(
                                ::fmod(cur_abs_phi, 2 * M_PI) *
                                (w.getPhi() < 0.0 ? -1.0 : 1.0));
        }

        m_loggers[LOGGER_POSE]->updateColumn(DL_TIMESTAMP, context.simul_time);
        m_loggers[LOGGER_POSE]->updateColumn(PL_Q_X, m_q.x);
        m_loggers[LOGGER_POSE]->updateColumn(PL_Q_Y, m_q.y);
        m_loggers[LOGGER_POSE]->updateColumn(PL_Q_Z, m_q.z);
        m_loggers[LOGGER_POSE]->updateColumn(PL_Q_YAW, m_q.yaw);
        m_loggers[LOGGER_POSE]->updateColumn(PL_Q_PITCH, m_q.pitch);
        m_loggers[LOGGER_POSE]->updateColumn(PL_Q_ROLL, m_q.roll);
        m_loggers[LOGGER_POSE]->updateColumn(PL_DQ_X, m_dq.vals[0]);
        m_loggers[LOGGER_POSE]->updateColumn(PL_DQ_Y, m_dq.vals[1]);
        m_loggers[LOGGER_POSE]->updateColumn(PL_DQ_Z, m_dq.vals[2]);

        {
                writeLogStrings();
        }
}

void VehicleBase::getWheelsVelocityLocal(
        std::vector<mrpt::math::TPoint2D>& vels, const vec3& veh_vel_local) const
{
        // Each wheel velocity is:
        // v_w = v_veh + \omega \times wheel_pos
        // =>
        // v_w = v_veh + ( -w*y, w*x )

        const double w = veh_vel_local.vals[2];  // vehicle w

        const size_t nW = this->getNumWheels();
        vels.resize(nW);
        for (size_t i = 0; i < nW; i++)
        {
                const Wheel& wheel = getWheelInfo(i);

                vels[i].x = veh_vel_local.vals[0] - w * wheel.y;
                vels[i].y = veh_vel_local.vals[1] + w * wheel.x;
        }
}

vec3 VehicleBase::getVelocityLocal() const
{
        vec3 local_vel;
        local_vel.vals[2] = m_dq.vals[2];  // omega remains the same.

        const mrpt::poses::CPose2D p(0, 0, -m_q.yaw);  // "-" means inverse pose
        p.composePoint(
                m_dq.vals[0], m_dq.vals[1], local_vel.vals[0], local_vel.vals[1]);
        return local_vel;
}

mrpt::poses::CPose2D VehicleBase::getCPose2D() const
{
        return mrpt::poses::CPose2D(mrpt::math::TPose2D(m_q));
}

void VehicleBase::gui_update_common(
        mrpt::opengl::COpenGLScene& scene, bool defaultVehicleBody)
{
        // 1st time call?? -> Create objects
        // ----------------------------------
        if (defaultVehicleBody)
        {
                const size_t nWs = this->getNumWheels();
                if (!m_gl_chassis)
                {
                        m_gl_chassis = mrpt::opengl::CSetOfObjects::Create();

                        // Wheels shape:
                        m_gl_wheels.resize(nWs);
                        for (size_t i = 0; i < nWs; i++)
                        {
                                m_gl_wheels[i] = mrpt::opengl::CSetOfObjects::Create();
                                this->getWheelInfo(i).getAs3DObject(*m_gl_wheels[i]);
                                m_gl_chassis->insert(m_gl_wheels[i]);
                        }
                        // Robot shape:
                        mrpt::opengl::CPolyhedron::Ptr gl_poly =
                                mrpt::opengl::CPolyhedron::CreateCustomPrism(
                                        m_chassis_poly, m_chassis_z_max - m_chassis_z_min);
                        gl_poly->setLocation(0, 0, m_chassis_z_min);
                        gl_poly->setColor(TColorf(m_chassis_color));
                        m_gl_chassis->insert(gl_poly);

                        SCENE_INSERT_Z_ORDER(scene, 1, m_gl_chassis);

                        // Visualization of forces:
                        m_gl_forces = mrpt::opengl::CSetOfLines::Create();
                        m_gl_forces->setLineWidth(3.0);
                        m_gl_forces->setColor_u8(TColor(0xff, 0xff, 0xff));

                        SCENE_INSERT_Z_ORDER(
                                scene, 3, m_gl_forces);  // forces are in global coords
                }

                // Update them:
                // ----------------------------------
                m_gl_chassis->setPose(m_q);

                for (size_t i = 0; i < nWs; i++)
                {
                        const Wheel& w = getWheelInfo(i);
                        m_gl_wheels[i]->setPose(
                                mrpt::math::TPose3D(
                                        w.x, w.y, 0.5 * w.diameter, w.yaw, w.getPhi(), 0.0));
                }
        }

        // Other common stuff:
        internal_gui_update_sensors(scene);
        internal_gui_update_forces(scene);
}

void VehicleBase::internal_gui_update_sensors(mrpt::opengl::COpenGLScene& scene)
{
        for (TListSensors::iterator it = m_sensors.begin(); it != m_sensors.end();
                 ++it)
                (*it)->gui_update(scene);
}

void VehicleBase::internal_gui_update_forces(mrpt::opengl::COpenGLScene& scene)
{
        if (m_world->m_gui_options.show_forces)
        {
                std::lock_guard<std::mutex> csl(m_force_segments_for_rendering_cs);
                m_gl_forces->clear();
                m_gl_forces->appendLines(m_force_segments_for_rendering);
                m_gl_forces->setVisibility(true);
        }
        else
        {
                m_gl_forces->setVisibility(false);
        }
}

void VehicleBase::updateMaxRadiusFromPoly()
{
        using namespace mrpt::math;

        m_max_radius = 0.001f;
        for (TPolygon2D::const_iterator it = m_chassis_poly.begin();
                 it != m_chassis_poly.end(); ++it)
        {
                const float n = it->norm();
    keep_max(m_max_radius, n);
        }
}

void VehicleBase::create_multibody_system(b2World* world)
{
        // Define the dynamic body. We set its position and call the body factory.
        b2BodyDef bodyDef;
        bodyDef.type = b2_dynamicBody;

        m_b2d_vehicle_body = world->CreateBody(&bodyDef);

        // Define shape of chassis:
        // ------------------------------
        {
                // Convert shape into Box2D format:
                const size_t nPts = m_chassis_poly.size();
                ASSERT_(nPts >= 3);
                ASSERT_BELOWEQ_(nPts, (size_t)b2_maxPolygonVertices);
                std::vector<b2Vec2> pts(nPts);
                for (size_t i = 0; i < nPts; i++)
                        pts[i] = b2Vec2(m_chassis_poly[i].x, m_chassis_poly[i].y);

                b2PolygonShape chassisPoly;
                chassisPoly.Set(&pts[0], nPts);
                // chassisPoly.m_radius = 1e-3;  // The "skin" depth of the body

                // Define the dynamic body fixture.
                b2FixtureDef fixtureDef;
                fixtureDef.shape = &chassisPoly;
                fixtureDef.restitution = 0.01;

                // Set the box density to be non-zero, so it will be dynamic.
                b2MassData mass;
                chassisPoly.ComputeMass(
                        &mass, 1);  // Mass with density=1 => compute area
                fixtureDef.density = m_chassis_mass / mass.mass;

                // Override the default friction.
                fixtureDef.friction = 0.3f;

                // Add the shape to the body.
                m_fixture_chassis = m_b2d_vehicle_body->CreateFixture(&fixtureDef);

                // Compute center of mass:
                b2MassData vehMass;
                m_fixture_chassis->GetMassData(&vehMass);
                m_chassis_com.x = vehMass.center.x;
                m_chassis_com.y = vehMass.center.y;
        }

        // Define shape of wheels:
        // ------------------------------
        ASSERT_EQUAL_(m_fixture_wheels.size(), m_wheels_info.size());

        for (size_t i = 0; i < m_wheels_info.size(); i++)
        {
                b2PolygonShape wheelShape;
                wheelShape.SetAsBox(
                        m_wheels_info[i].diameter * 0.5, m_wheels_info[i].width * 0.5,
                        b2Vec2(m_wheels_info[i].x, m_wheels_info[i].y),
                        m_wheels_info[i].yaw);

                // Define the dynamic body fixture.
                b2FixtureDef fixtureDef;
                fixtureDef.shape = &wheelShape;
                fixtureDef.restitution = 0.05;

                // Set the box density to be non-zero, so it will be dynamic.
                b2MassData mass;
                wheelShape.ComputeMass(
                        &mass, 1);  // Mass with density=1 => compute area
                fixtureDef.density = m_wheels_info[i].mass / mass.mass;

                // Override the default friction.
                fixtureDef.friction = 0.5f;

                m_fixture_wheels[i] = m_b2d_vehicle_body->CreateFixture(&fixtureDef);
        }
}

void VehicleBase::gui_update(mrpt::opengl::COpenGLScene& scene)
{
        this->gui_update_common(scene);  // Common part: update sensors, etc.
}

void VehicleBase::initLoggers()
{
        m_loggers[LOGGER_POSE] = std::make_shared<CSVLogger>();
        //  m_loggers[LOGGER_POSE]->addColumn(DL_TIMESTAMP);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_Q_X);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_Q_Y);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_Q_Z);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_Q_YAW);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_Q_PITCH);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_Q_ROLL);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_DQ_X);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_DQ_Y);
        //  m_loggers[LOGGER_POSE]->addColumn(PL_DQ_Z);
        m_loggers[LOGGER_POSE]->setFilepath(
                m_log_path + "mvsim_" + m_name + LOGGER_POSE + ".log");

        for (size_t i = 0; i < getNumWheels(); i++)
        {
                m_loggers[LOGGER_WHEEL + std::to_string(i + 1)] =
                        std::make_shared<CSVLogger>();
                //    m_loggers[LOGGER_WHEEL + std::to_string(i +
                //    1)]->addColumn(DL_TIMESTAMP);
                //    m_loggers[LOGGER_WHEEL + std::to_string(i +
                //    1)]->addColumn(WL_TORQUE);
                //    m_loggers[LOGGER_WHEEL + std::to_string(i +
                //    1)]->addColumn(WL_WEIGHT);
                //    m_loggers[LOGGER_WHEEL + std::to_string(i +
                //    1)]->addColumn(WL_VEL_X);
                //    m_loggers[LOGGER_WHEEL + std::to_string(i +
                //    1)]->addColumn(WL_VEL_Y);
                //    m_loggers[LOGGER_WHEEL + std::to_string(i +
                //    1)]->addColumn(WL_FRIC_X);
                //    m_loggers[LOGGER_WHEEL + std::to_string(i +
                //    1)]->addColumn(WL_FRIC_Y);
                m_loggers[LOGGER_WHEEL + std::to_string(i + 1)]->setFilepath(
                        m_log_path + "mvsim_" + m_name + LOGGER_WHEEL +
                        std::to_string(i + 1) + ".log");
        }
}

void VehicleBase::writeLogStrings()
{
        std::map<std::string, std::shared_ptr<CSVLogger>>::iterator it;
        for (it = m_loggers.begin(); it != m_loggers.end(); ++it)
        {
                it->second->writeRow();
        }
}

void VehicleBase::apply_force(
        double fx, double fy, double local_ptx, double local_pty)
{
        ASSERT_(m_b2d_vehicle_body);
        const b2Vec2 wPt = m_b2d_vehicle_body->GetWorldPoint(
                b2Vec2(local_ptx, local_pty));  // Application point -> world coords
        m_b2d_vehicle_body->ApplyForce(b2Vec2(fx, fy), wPt, true /*wake up*/);
}