mirror of https://github.com/ArduPilot/ardupilot
421 lines
15 KiB
C++
421 lines
15 KiB
C++
/*
|
||
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/>.
|
||
*/
|
||
/*
|
||
helicopter simulator class
|
||
*/
|
||
|
||
#include "SIM_Helicopter.h"
|
||
|
||
#include <stdio.h>
|
||
|
||
namespace SITL {
|
||
|
||
Helicopter::Helicopter(const char *frame_str) :
|
||
Aircraft(frame_str)
|
||
{
|
||
mass = 4.54f;
|
||
|
||
if (strstr(frame_str, "-dual")) {
|
||
frame_type = HELI_FRAME_DUAL;
|
||
_time_delay = 30;
|
||
nominal_rpm = 1300;
|
||
} else if (strstr(frame_str, "-compound")) {
|
||
frame_type = HELI_FRAME_COMPOUND;
|
||
_time_delay = 50;
|
||
nominal_rpm = 1500;
|
||
} else if (strstr(frame_str, "-blade360")) {
|
||
frame_type = HELI_FRAME_BLADE360;
|
||
_time_delay = 40;
|
||
nominal_rpm = 2100;
|
||
} else {
|
||
frame_type = HELI_FRAME_CONVENTIONAL;
|
||
_time_delay = 50;
|
||
nominal_rpm = 1500;
|
||
}
|
||
|
||
/*
|
||
For conventional and compound
|
||
scaling from motor power to Newtons. Allows the copter
|
||
to hover against gravity when the motor is at hover_throttle
|
||
normalized to hover at 1500RPM at 5 deg collective.
|
||
*/
|
||
thrust_scale = (mass * GRAVITY_MSS) / (hover_coll * sq(nominal_rpm * 2.0f * M_PI / 60.0f));
|
||
|
||
// calculates tail rotor thrust to overcome rotor torque using the lean angle in a hover
|
||
torque_scale = 0.83f * mass * GRAVITY_MSS * sinf(radians(hover_lean)) * tr_dist / (hover_coll * sq(nominal_rpm * 2.0f * M_PI / 60.0f));
|
||
|
||
// torque with zero collective pitch. Percentage of total hover torque is based on full scale helicopters.
|
||
torque_mpog = 0.17f * mass * GRAVITY_MSS * sinf(radians(hover_lean)) * tr_dist / sq(nominal_rpm * 2.0f * M_PI / 60.0f);
|
||
|
||
frame_height = 0.1;
|
||
|
||
gas_heli = (strstr(frame_str, "-gas") != nullptr);
|
||
|
||
ground_behavior = GROUND_BEHAVIOR_NO_MOVEMENT;
|
||
lock_step_scheduled = true;
|
||
}
|
||
|
||
/*
|
||
update the helicopter simulation by one time step
|
||
*/
|
||
void Helicopter::update(const struct sitl_input &input)
|
||
{
|
||
const float dt = frame_time_us * 1.0e-6f;
|
||
|
||
// get wind vector setup
|
||
update_wind(input);
|
||
|
||
motor_interlock = input.servos[7] > 1400;
|
||
|
||
float rsc = constrain_float((input.servos[7]-1000) / 1000.0f, 0, 1);
|
||
float rsc_scale = rsc/rsc_setpoint;
|
||
|
||
float thrust = 0;
|
||
float roll_rate = 0;
|
||
float pitch_rate = 0;
|
||
float yaw_rate = 0;
|
||
float torque_effect_accel = 0;
|
||
float lateral_x_thrust = 0;
|
||
float lateral_y_thrust = 0;
|
||
|
||
|
||
if (_time_delay == 0) {
|
||
for (uint8_t i = 0; i < 6; i++) {
|
||
_servos_delayed[i] = input.servos[i];
|
||
}
|
||
} else if (servos_stored_buffer == nullptr) {
|
||
uint16_t buffer_size = constrain_int16(_time_delay, 1, 100) * 0.001f / dt;
|
||
servos_stored_buffer = new ObjectBuffer<servos_stored>(buffer_size);
|
||
while (servos_stored_buffer->space() != 0) {
|
||
push_to_buffer(input.servos);
|
||
}
|
||
for (uint8_t i = 0; i < 6; i++) {
|
||
_servos_delayed[i] = input.servos[i];
|
||
}
|
||
} else {
|
||
pull_from_buffer(_servos_delayed);
|
||
push_to_buffer(input.servos);
|
||
}
|
||
|
||
float swash1 = (_servos_delayed[0]-1000) / 1000.0f;
|
||
float swash2 = (_servos_delayed[1]-1000) / 1000.0f;
|
||
float swash3 = (_servos_delayed[2]-1000) / 1000.0f;
|
||
|
||
|
||
|
||
Vector3f rot_accel;
|
||
Vector3f air_resistance;
|
||
|
||
switch (frame_type) {
|
||
case HELI_FRAME_CONVENTIONAL: {
|
||
// simulate a traditional helicopter
|
||
|
||
float Ma1s = 617.5f;
|
||
float Lb1s = 3588.6f;
|
||
float Mu = 0.003f;
|
||
float Lv = -0.006;
|
||
float Xu = -0.125;
|
||
float Yv = -0.375;
|
||
float Zw = -0.375;
|
||
|
||
float tail_rotor = (_servos_delayed[3]-1000) / 1000.0f;
|
||
|
||
// determine RPM
|
||
rpm[0] = update_rpm(motor_interlock, dt);
|
||
|
||
// thrust calculated based on 5 deg hover collective for 10lb aircraft at 1500RPM
|
||
float coll = 50.0f * (swash1+swash2+swash3) / 3.0f - 25.0f;
|
||
thrust = thrust_scale * sq(rpm[0] * 0.104667f) * (0.25* (coll - hover_coll) + hover_coll);
|
||
|
||
// Calculate main rotor torque effect on body
|
||
torque_effect_accel = -1 * sq(rpm[0] * 0.104667f) * (torque_mpog + torque_scale * fabsf(coll)) / izz;
|
||
|
||
// Calculate rotor tip path plane angle
|
||
float roll_cyclic = 1.283 * (swash1 - swash2) / cyclic_scalar;
|
||
float pitch_cyclic = 1.48 * ((swash1+swash2) / 2.0f - swash3) / cyclic_scalar;
|
||
Vector2f ctrl_pos = Vector2f(roll_cyclic, pitch_cyclic);
|
||
update_rotor_dynamics(gyro, ctrl_pos, _tpp_angle, dt);
|
||
|
||
float yaw_cmd = 2.0f * tail_rotor - 1.0f; // convert range to -1 to 1
|
||
float tail_rotor_torque = (21.6f * 2.96f * yaw_cmd - 2.96f * gyro.z) * sq(rpm[0]/nominal_rpm);
|
||
float tail_rotor_thrust = -1.0f * tail_rotor_torque * izz / tr_dist; //right pedal produces left body accel
|
||
|
||
// rotational acceleration, in rad/s/s, in body frame
|
||
rot_accel.x = _tpp_angle.x * Lb1s + Lv * velocity_air_bf.y;
|
||
rot_accel.y = _tpp_angle.y * Ma1s + Mu * velocity_air_bf.x;
|
||
rot_accel.z = tail_rotor_torque + torque_effect_accel;
|
||
|
||
lateral_y_thrust = tail_rotor_thrust / mass + GRAVITY_MSS * _tpp_angle.x + Yv * velocity_air_bf.y;
|
||
lateral_x_thrust = -1.0f * GRAVITY_MSS * _tpp_angle.y + Xu * velocity_air_bf.x;
|
||
accel_body = Vector3f(lateral_x_thrust, lateral_y_thrust, -thrust / mass + velocity_air_bf.z * Zw);
|
||
|
||
break;
|
||
}
|
||
|
||
case HELI_FRAME_BLADE360: {
|
||
// simulate a Blade 360 helicopter. This model was taken from the following reference.
|
||
// Walker, J, Tishler, M, "Identification and Control Design of a Sub-Scale Flybarless Helicopter",
|
||
// Vertical Flight Society’s 77th Annual Forum & Technology Display, Virtual, May 10-14, 2021.
|
||
|
||
float Ma1s = 796.7f;
|
||
float Lb1s = 5115.2f;
|
||
float Mu = 2.7501f;
|
||
float Mv = -2.3039f;
|
||
float Lu = -28.7796f;
|
||
float Lv = -5.5376f;
|
||
float Xu = -0.2270f;
|
||
float Yv = -0.1852f;
|
||
float Yp = 0.2303f;
|
||
float Zw = -0.5910f;
|
||
float Nr = -2.0131f;
|
||
float Nw = 5.7574f;
|
||
float Nv = 1.7258f;
|
||
float Ncol = -32.4616f;
|
||
float Nped = 63.0040f;
|
||
float Zcol = -22.3239f;
|
||
|
||
float tail_rotor = (_servos_delayed[3]-1000) / 1000.0f;
|
||
|
||
// determine RPM
|
||
rpm[0] = update_rpm(motor_interlock, dt);
|
||
|
||
// collective adjusted for coll_min(1460) to coll_max(1740) as 0 to 1 with 1500 being zero thrust
|
||
float coll = 3.51 * ((swash1+swash2+swash3) / 3.0f - 0.5f);
|
||
|
||
// Calculate rotor tip path plane angle
|
||
float roll_cyclic = 1.283f * (swash1 - swash2);
|
||
float pitch_cyclic = 1.48f * ((swash1+swash2) / 2.0f - swash3);
|
||
Vector2f ctrl_pos = Vector2f(roll_cyclic, pitch_cyclic);
|
||
update_rotor_dynamics(gyro, ctrl_pos, _tpp_angle, dt);
|
||
|
||
float yaw_cmd = 1.45f * (2.0f * tail_rotor - 1.0f); // convert range to -1 to 1
|
||
|
||
// rotational acceleration, in rad/s/s, in body frame
|
||
rot_accel.x = _tpp_angle.x * Lb1s + Lu * velocity_air_bf.x + Lv * velocity_air_bf.y;
|
||
rot_accel.y = _tpp_angle.y * Ma1s + Mu * velocity_air_bf.x + Mv * velocity_air_bf.y;
|
||
rot_accel.z = Nv * velocity_air_bf.y + Nr * gyro.z + sq(rpm[0]/nominal_rpm) * Nped * yaw_cmd + Nw * velocity_air_bf.z + sq(rpm[0]/nominal_rpm) * Ncol * (coll - 0.5f);
|
||
|
||
lateral_y_thrust = GRAVITY_MSS * _tpp_angle.x + Yv * velocity_air_bf.y + Yp * gyro.x - 3.2 * 0.01745 * GRAVITY_MSS;
|
||
lateral_x_thrust = -1.0f * GRAVITY_MSS * _tpp_angle.y + Xu * velocity_air_bf.x;
|
||
float vertical_thrust = Zcol * coll * sq(rpm[0]/nominal_rpm) + velocity_air_bf.z * Zw;
|
||
accel_body = Vector3f(lateral_x_thrust, lateral_y_thrust, vertical_thrust);
|
||
|
||
break;
|
||
}
|
||
|
||
case HELI_FRAME_DUAL: {
|
||
// simulate a tandem helicopter
|
||
thrust_scale = (mass * GRAVITY_MSS) / hover_throttle;
|
||
|
||
float swash4 = (_servos_delayed[3]-1000) / 1000.0f;
|
||
float swash5 = (_servos_delayed[4]-1000) / 1000.0f;
|
||
float swash6 = (_servos_delayed[5]-1000) / 1000.0f;
|
||
|
||
thrust = (rsc / rsc_setpoint) * (swash1+swash2+swash3+swash4+swash5+swash6) / 6.0f;
|
||
torque_effect_accel = (rsc_scale + rsc / rsc_setpoint) * rotor_rot_accel * ((swash1+swash2+swash3) - (swash4+swash5+swash6));
|
||
|
||
roll_rate = (swash1-swash2) + (swash4-swash5);
|
||
pitch_rate = (swash1+swash2+swash3) - (swash4+swash5+swash6);
|
||
yaw_rate = (swash1-swash2) + (swash5-swash4);
|
||
|
||
roll_rate *= rsc_scale;
|
||
pitch_rate *= rsc_scale;
|
||
yaw_rate *= rsc_scale;
|
||
|
||
// rotational acceleration, in rad/s/s, in body frame
|
||
rot_accel.x = roll_rate * roll_rate_max;
|
||
rot_accel.y = pitch_rate * pitch_rate_max;
|
||
rot_accel.z = yaw_rate * 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;
|
||
|
||
// torque effect on tail
|
||
rot_accel.z += torque_effect_accel;
|
||
|
||
// air resistance
|
||
air_resistance = -velocity_air_ef * (GRAVITY_MSS/terminal_velocity);
|
||
|
||
// simulate rotor speed
|
||
rpm[0] = thrust * nominal_rpm;
|
||
|
||
// scale thrust to newtons
|
||
thrust *= thrust_scale;
|
||
|
||
accel_body = Vector3f(lateral_x_thrust, lateral_y_thrust, -thrust / mass);
|
||
accel_body += dcm.transposed() * air_resistance;
|
||
|
||
break;
|
||
}
|
||
|
||
case HELI_FRAME_COMPOUND: {
|
||
// simulate a compound helicopter
|
||
|
||
float Ma1s = 617.5f;
|
||
float Lb1s = 3588.6f;
|
||
float Mu = 0.003f;
|
||
float Lv = -0.006;
|
||
float Xu = -0.125;
|
||
float Yv = -0.375;
|
||
float Zw = -0.375;
|
||
|
||
// determine RPM
|
||
rpm[0] = update_rpm(motor_interlock, dt);
|
||
|
||
// thrust calculated based on 5 deg hover collective for 10lb aircraft at 1500RPM
|
||
float coll = 50.0f * (swash1+swash2+swash3) / 3.0f - 25.0f;
|
||
thrust = thrust_scale * sq(rpm[0] * 0.104667f) * (0.25* (coll - hover_coll) + hover_coll);
|
||
|
||
// Calculate main rotor torque effect on body
|
||
torque_effect_accel = -1 * sq(rpm[0] * 0.104667f) * (torque_mpog + torque_scale * fabsf(coll)) / izz;
|
||
|
||
// Calculate rotor tip path plane angle
|
||
float roll_cyclic = 1.283 * (swash1 - swash2) / cyclic_scalar;
|
||
float pitch_cyclic = 1.48 * ((swash1+swash2) / 2.0f - swash3) / cyclic_scalar;
|
||
Vector2f ctrl_pos = Vector2f(roll_cyclic, pitch_cyclic);
|
||
update_rotor_dynamics(gyro, ctrl_pos, _tpp_angle, dt);
|
||
|
||
// Calculate thruster yaw and forward thrust effects
|
||
// Thruster command range -1 to 1. Positive is forward thrust for both
|
||
float right_thruster_cmd = 2.0f * (_servos_delayed[3]-1000) / 1000.0f - 1.0f;
|
||
float left_thruster_cmd = 2.0f * (_servos_delayed[4]-1000) / 1000.0f - 1.0f;
|
||
|
||
// assume torque from each thruster only half of normal tailrotor since thrusters 1/2 distance from cg
|
||
float right_thruster_torque = (-0.5f * 21.6f * 2.96f * right_thruster_cmd - 2.96f * gyro.z) * sq(rpm[0] / nominal_rpm);
|
||
float left_thruster_torque = (0.5f * 21.6f * 2.96f * left_thruster_cmd - 2.96f * gyro.z) * sq(rpm[0] / nominal_rpm);
|
||
|
||
float right_thruster_force = -1.0f * right_thruster_torque * izz / (0.5f * tr_dist);
|
||
float left_thruster_force = left_thruster_torque * izz / (0.5f * tr_dist);
|
||
|
||
// rotational acceleration, in rad/s/s, in body frame
|
||
rot_accel.x = _tpp_angle.x * Lb1s + Lv * velocity_air_bf.y;
|
||
rot_accel.y = _tpp_angle.y * Ma1s + Mu * velocity_air_bf.x;
|
||
rot_accel.z = right_thruster_torque + left_thruster_torque + torque_effect_accel;
|
||
|
||
lateral_y_thrust = GRAVITY_MSS * _tpp_angle.x + Yv * velocity_air_bf.y;
|
||
lateral_x_thrust = (right_thruster_force + left_thruster_force) / mass - GRAVITY_MSS * _tpp_angle.y + Xu * velocity_air_bf.x;
|
||
accel_body = Vector3f(lateral_x_thrust, lateral_y_thrust, -thrust / mass + velocity_air_bf.z * Zw);
|
||
|
||
break;
|
||
}
|
||
}
|
||
|
||
|
||
update_dynamics(rot_accel);
|
||
|
||
// update lat/lon/altitude
|
||
update_position();
|
||
time_advance();
|
||
|
||
// update magnetic field
|
||
update_mag_field_bf();
|
||
}
|
||
|
||
void Helicopter::update_rotor_dynamics(Vector3f gyros, Vector2f ctrl_pos, Vector2f &tpp_angle, float dt)
|
||
{
|
||
|
||
float tf_inv;
|
||
float Lfa1s;
|
||
float Mfb1s;
|
||
float Lflt;
|
||
float Lflg;
|
||
float Mflt;
|
||
float Mflg;
|
||
|
||
if (frame_type == HELI_FRAME_BLADE360) {
|
||
tf_inv = 1.0f / 0.0353f;
|
||
Lfa1s = 1.0477f;
|
||
Mfb1s = -1.0057f;
|
||
Lflt = 0.2375f;
|
||
Lflg = -0.0286f;
|
||
Mflt = 0.0344f;
|
||
Mflg = 0.2292f;
|
||
} else {
|
||
tf_inv = 1.0f / 0.068232f;
|
||
Lfa1s = 1.2963f;
|
||
Mfb1s = -1.3402f;
|
||
Lflt = 1.7635f;
|
||
Lflg = -0.61171f;
|
||
Mflt = 0.52454f;
|
||
Mflg = 1.9432f;
|
||
}
|
||
|
||
float b1s_dot = -1 * gyro.x - tf_inv * tpp_angle.x + tf_inv * (Lfa1s * tpp_angle.y + Lflt * ctrl_pos.x + Lflg * ctrl_pos.y);
|
||
float a1s_dot = -1 * gyro.y - tf_inv * tpp_angle.y + tf_inv * (Mfb1s * tpp_angle.x + Mflt * ctrl_pos.x + Mflg * ctrl_pos.y);
|
||
|
||
tpp_angle.x += b1s_dot * dt;
|
||
tpp_angle.y += a1s_dot * dt;
|
||
|
||
}
|
||
|
||
float Helicopter::update_rpm(bool interlock, float dt)
|
||
{
|
||
static float rotor_runup_output;
|
||
float runup_time = 8.0f;
|
||
// ramp speed estimate towards control out
|
||
float runup_increment = dt / runup_time;
|
||
if (interlock) {
|
||
if (rotor_runup_output < 1.0f) {
|
||
rotor_runup_output += runup_increment;
|
||
} else {
|
||
rotor_runup_output = 1.0f;
|
||
}
|
||
}else{
|
||
if (rotor_runup_output > 0.0f) {
|
||
rotor_runup_output -= runup_increment;
|
||
} else {
|
||
rotor_runup_output = 0.0f;
|
||
}
|
||
}
|
||
|
||
return nominal_rpm * constrain_float(rotor_runup_output,0.0f,1.0f);
|
||
|
||
}
|
||
|
||
// push servo input to buffer
|
||
void Helicopter::push_to_buffer(const uint16_t servos_input[16])
|
||
{
|
||
servos_stored sample;
|
||
sample.servo1 = servos_input[0];
|
||
sample.servo2 = servos_input[1];
|
||
sample.servo3 = servos_input[2];
|
||
sample.servo4 = servos_input[3];
|
||
sample.servo5 = servos_input[4];
|
||
sample.servo6 = servos_input[5];
|
||
servos_stored_buffer->push(sample);
|
||
|
||
}
|
||
|
||
// pull servo delay from buffer
|
||
void Helicopter::pull_from_buffer(uint16_t servos_delayed[6])
|
||
{
|
||
servos_stored sample;
|
||
if (!servos_stored_buffer->pop(sample)) {
|
||
// no sample
|
||
return;
|
||
}
|
||
servos_delayed[0] = sample.servo1;
|
||
servos_delayed[1] = sample.servo2;
|
||
servos_delayed[2] = sample.servo3;
|
||
servos_delayed[3] = sample.servo4;
|
||
servos_delayed[4] = sample.servo5;
|
||
servos_delayed[5] = sample.servo6;
|
||
|
||
}
|
||
|
||
} // namespace SITL
|