VehicleAckermann_ControllerTwistFrontSteerPID.cpp

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/*+-------------------------------------------------------------------------+
  |                       MultiVehicle simulator (libmvsim)                 |
  |                                                                         |
  | Copyright (C) 2014-2023  Jose Luis Blanco Claraco                       |
  | Copyright (C) 2017  Borys Tymchenko (Odessa Polytechnic University)     |
  | Distributed under 3-clause BSD License                                  |
  |   See COPYING                                                           |
  +-------------------------------------------------------------------------+ */

#include <mvsim/VehicleDynamics/VehicleAckermann.h>

#include "xml_utils.h"

using namespace mvsim;
using namespace std;

DynamicsAckermann::ControllerTwistFrontSteerPID::ControllerTwistFrontSteerPID(
        DynamicsAckermann& veh)
        : ControllerBase(veh),
          setpoint_lin_speed(0),
          setpoint_ang_speed(0),
          KP(100),
          KI(0),
          KD(0),
          max_torque(100.0)
{
        // Get distance between wheels:
        dist_fWheels_ =
                veh_.wheels_info_[WHEEL_FL].y - veh_.wheels_info_[WHEEL_FR].y;
        r2f_L_ = veh_.wheels_info_[WHEEL_FL].x - veh_.wheels_info_[WHEEL_RL].x;
        ASSERT_(dist_fWheels_ > 0.0);
        ASSERT_(r2f_L_ > 0.0);
}

// See base class docs
void DynamicsAckermann::ControllerTwistFrontSteerPID::control_step(
        const DynamicsAckermann::TControllerInput& ci,
        DynamicsAckermann::TControllerOutput& co)
{
        // For each wheel:
        // 1) Compute desired velocity set-point (in m/s)
        // 2) Run the PI/PID for that wheel independently (in newtons)

        // 1st: desired steering angle:
        // --------------------------------
        if (setpoint_ang_speed == 0)
        {
                co.steer_ang = 0.0;
        }
        else
        {
                const double R = setpoint_lin_speed / setpoint_ang_speed;
                co.steer_ang = atan(r2f_L_ / R);
        }

        // Desired velocities for each wheel
        // In local vehicle frame:
        const std::vector<mrpt::math::TVector2D> desired_wheel_vels =
                veh_.getWheelsVelocityLocal(
                        mrpt::math::TTwist2D(setpoint_lin_speed, 0.0, setpoint_ang_speed));

        ASSERT_(desired_wheel_vels.size() == 4);

        // Rotate to obtain the actual desired longitudinal velocity for each wheel:
        // FL:
        double vel_fl, vel_fr;
        double desired_fl_steer_ang, desired_fr_steer_ang;
        veh_.computeFrontWheelAngles(
                co.steer_ang, desired_fl_steer_ang, desired_fr_steer_ang);
        {
                const mrpt::poses::CPose2D wRotInv(0, 0, -desired_fl_steer_ang);
                mrpt::math::TPoint2D vel_w;
                wRotInv.composePoint(
                        desired_wheel_vels[DynamicsAckermann::WHEEL_FL], vel_w);
                vel_fl = vel_w.x;
        }
        {
                const mrpt::poses::CPose2D wRotInv(0, 0, -desired_fr_steer_ang);
                mrpt::math::TPoint2D vel_w;
                wRotInv.composePoint(
                        desired_wheel_vels[DynamicsAckermann::WHEEL_FR], vel_w);
                vel_fr = vel_w.x;
        }

        // Compute each wheel actual velocity (from an "odometry" estimation of
        // velocity, not ground-truth!):
        double act_vel_fl, act_vel_fr;
        {
                // In local vehicle frame:
                const std::vector<mrpt::math::TVector2D> odo_wheel_vels =
                        veh_.getWheelsVelocityLocal(veh_.getVelocityLocalOdoEstimate());
                ASSERT_(odo_wheel_vels.size() == 4);

                const double actual_fl_steer_ang =
                        veh_.getWheelInfo(DynamicsAckermann::WHEEL_FL).yaw;
                const double actual_fr_steer_ang =
                        veh_.getWheelInfo(DynamicsAckermann::WHEEL_FR).yaw;

                {
                        const mrpt::poses::CPose2D wRotInv(0, 0, -actual_fl_steer_ang);
                        mrpt::math::TPoint2D vel_w;
                        wRotInv.composePoint(
                                odo_wheel_vels[DynamicsAckermann::WHEEL_FL], vel_w);
                        act_vel_fl = vel_w.x;
                }
                {
                        const mrpt::poses::CPose2D wRotInv(0, 0, -actual_fr_steer_ang);
                        mrpt::math::TPoint2D vel_w;
                        wRotInv.composePoint(
                                odo_wheel_vels[DynamicsAckermann::WHEEL_FR], vel_w);
                        act_vel_fr = vel_w.x;
                }
        }

        // Apply controller:
        for (int i = 0; i < 2; i++)
        {
                PID_[i].KP = KP;
                PID_[i].KI = KI;
                PID_[i].KD = KD;
                PID_[i].max_out = max_torque;
        }

        co.rl_torque = .0;
        co.rr_torque = .0;
        co.fl_torque = -PID_[0].compute(
                vel_fl - act_vel_fl,
                ci.context.dt);  // "-" because \tau<0 makes robot moves forwards.
        co.fr_torque = -PID_[1].compute(vel_fr - act_vel_fr, ci.context.dt);
}

void DynamicsAckermann::ControllerTwistFrontSteerPID::load_config(
        const rapidxml::xml_node<char>& node)
{
        TParameterDefinitions params;
        params["KP"] = TParamEntry("%lf", &KP);
        params["KI"] = TParamEntry("%lf", &KI);
        params["KD"] = TParamEntry("%lf", &KD);
        params["max_torque"] = TParamEntry("%lf", &max_torque);

        // Initial speed.
        params["V"] = TParamEntry("%lf", &this->setpoint_lin_speed);
        params["W"] = TParamEntry("%lf_deg", &this->setpoint_ang_speed);

        parse_xmlnode_children_as_param(node, params);
}

void DynamicsAckermann::ControllerTwistFrontSteerPID::teleop_interface(
        const TeleopInput& in, TeleopOutput& out)
{
        ControllerBase::teleop_interface(in, out);

        switch (in.keycode)
        {
                case 'W':
                case 'w':
                        setpoint_lin_speed += 0.1;
                        break;

                case 'S':
                case 's':
                        setpoint_lin_speed -= 0.1;
                        break;

                case 'A':
                case 'a':
                        setpoint_ang_speed += 1.0 * M_PI / 180.0;
                        break;

                case 'D':
                case 'd':
                        setpoint_ang_speed -= 1.0 * M_PI / 180.0;
                        break;

                case ' ':
                        setpoint_lin_speed = .0;
                        setpoint_ang_speed = .0;
                        break;
        };
        out.append_gui_lines += "[Controller=" + string(class_name()) +
                                                        "] Teleop keys: w/s=incr/decr lin speed. "
                                                        "a/d=left/right steering. spacebar=stop.\n";
        out.append_gui_lines += mrpt::format(
                "setpoint: v=%.03f w=%.03f deg/s\n", setpoint_lin_speed,
                setpoint_ang_speed * 180.0 / M_PI);
}