ardupilot/libraries/SITL/SIM_SingleCopter.cpp

119 lines
3.8 KiB
C++

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
This program 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.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
singlecopter simulator class
*/
#include "SIM_SingleCopter.h"
#include <stdio.h>
using namespace SITL;
SingleCopter::SingleCopter(const char *home_str, const char *frame_str) :
Aircraft(home_str, frame_str)
{
mass = 2.0f;
if (strstr(frame_str, "coax")) {
frame_type = FRAME_COAX;
} else {
frame_type = FRAME_SINGLE;
}
/*
scaling from motor power to Newtons. Allows the copter
to hover against gravity when the motor is at hover_throttle
*/
thrust_scale = (mass * GRAVITY_MSS) / hover_throttle;
frame_height = 0.1;
}
/*
update the copter simulation by one time step
*/
void SingleCopter::update(const struct sitl_input &input)
{
// get wind vector setup
update_wind(input);
float actuator[4];
for (uint8_t i=0; i<4; i++) {
actuator[i] = constrain_float((input.servos[i]-1500) / 500.0f, -1, 1);
}
float thrust;
float yaw_thrust;
float roll_thrust;
float pitch_thrust;
switch (frame_type) {
case FRAME_SINGLE:
thrust = constrain_float((input.servos[4]-1000) / 1000.0f, 0, 1);
yaw_thrust = -(actuator[0] + actuator[1] + actuator[2] + actuator[3]) * 0.25f * thrust + thrust * rotor_rot_accel;
roll_thrust = (actuator[0] - actuator[2]) * 0.5f * thrust;
pitch_thrust = (actuator[1] - actuator[3]) * 0.5f * thrust;
break;
case FRAME_COAX:
default: {
float motor1 = constrain_float((input.servos[4]-1000) / 1000.0f, 0, 1);
float motor2 = constrain_float((input.servos[5]-1000) / 1000.0f, 0, 1);
thrust = 0.5f*(motor1 + motor2);
yaw_thrust = -(actuator[0] + actuator[1] + actuator[2] + actuator[3]) * 0.25f * thrust + (motor2 - motor1) * rotor_rot_accel;
roll_thrust = (actuator[0] - actuator[2]) * 0.5f * thrust;
pitch_thrust = (actuator[1] - actuator[3]) * 0.5f * thrust;
break;
}
}
// rotational acceleration, in rad/s/s, in body frame
Vector3f rot_accel(roll_thrust * roll_rate_max,
pitch_thrust * pitch_rate_max,
yaw_thrust * yaw_rate_max);
// rotational air resistance
rot_accel.x -= gyro.x * radians(5000.0) / terminal_rotation_rate;
rot_accel.y -= gyro.y * radians(5000.0) / terminal_rotation_rate;
rot_accel.z -= gyro.z * radians(400.0) / terminal_rotation_rate;
// air resistance
Vector3f air_resistance = -velocity_air_ef * (GRAVITY_MSS/terminal_velocity);
// scale thrust to newtons
thrust *= thrust_scale;
accel_body = Vector3f(0, 0, -thrust / mass);
accel_body += dcm.transposed() * air_resistance;
bool was_on_ground = on_ground(position);
update_dynamics(rot_accel);
// constrain height to the ground
if (on_ground(position) && !was_on_ground) {
// zero roll/pitch, but keep yaw
float r, p, y;
dcm.to_euler(&r, &p, &y);
dcm.from_euler(0, 0, y);
position.z = -(ground_level + frame_height - home.alt*0.01f);
velocity_ef.zero();
}
// update lat/lon/altitude
update_position();
}