Line data    Source code

       1             : /*
       2             :    This program is free software: you can redistribute it and/or modify
       3             :    it under the terms of the GNU General Public License as published by
       4             :    the Free Software Foundation, either version 3 of the License, or
       5             :    (at your option) any later version.
       6             : 
       7             :    This program is distributed in the hope that it will be useful,
       8             :    but WITHOUT ANY WARRANTY; without even the implied warranty of
       9             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      10             :    GNU General Public License for more details.
      11             : 
      12             :    You should have received a copy of the GNU General Public License
      13             :    along with this program.  If not, see <http://www.gnu.org/licenses/>.
      14             :  */
      15             : /*
      16             :   singlecopter simulator class
      17             : */
      18             : 
      19             : #include "SIM_SingleCopter.h"
      20             : 
      21             : #include <stdio.h>
      22             : 
      23             : using namespace SITL;
      24             : 
      25           2 : SingleCopter::SingleCopter(const char *frame_str) :
      26           2 :     Aircraft(frame_str)
      27             : {
      28           2 :     mass = 2.0f;
      29             : 
      30           2 :     if (strstr(frame_str, "coax")) {
      31           1 :         frame_type = FRAME_COAX;
      32             :     } else {
      33           1 :         frame_type = FRAME_SINGLE;
      34             :     }
      35             :     
      36             :     /*
      37             :        scaling from motor power to Newtons. Allows the copter
      38             :        to hover against gravity when the motor is at hover_throttle
      39             :     */
      40           2 :     thrust_scale = (mass * GRAVITY_MSS) / hover_throttle;
      41           2 :     frame_height = 0.1;
      42           2 :     lock_step_scheduled = true;
      43           2 : }
      44             : 
      45             : /*
      46             :   update the copter simulation by one time step
      47             :  */
      48      308161 : void SingleCopter::update(const struct sitl_input &input)
      49             : {
      50             :     // get wind vector setup
      51      308161 :     update_wind(input);
      52             : 
      53             :     float actuator[4];
      54     1540805 :     for (uint8_t i=0; i<4; i++) {
      55     1232644 :         actuator[i] = constrain_float((input.servos[i]-1500) / 500.0f, -1, 1);
      56             :     }
      57             :     float thrust;
      58             :     float yaw_thrust;
      59             :     float roll_thrust;
      60             :     float pitch_thrust;
      61             : 
      62      308161 :     switch (frame_type) {
      63      154058 :     case FRAME_SINGLE:
      64      154058 :         thrust = constrain_float((input.servos[4]-1000) / 1000.0f, 0, 1);
      65      154058 :         yaw_thrust   = -(actuator[0] + actuator[1] + actuator[2] + actuator[3]) * 0.25f * thrust + thrust * rotor_rot_accel;
      66      154058 :         roll_thrust  = (actuator[0] - actuator[2]) * 0.5f * thrust;
      67      154058 :         pitch_thrust = (actuator[1] - actuator[3]) * 0.5f * thrust;
      68      154058 :         break;
      69             : 
      70      154103 :     case FRAME_COAX:
      71             :     default: {
      72      154103 :         float motor1 = constrain_float((input.servos[4]-1000) / 1000.0f, 0, 1);
      73      154103 :         float motor2 = constrain_float((input.servos[5]-1000) / 1000.0f, 0, 1);
      74      154103 :         thrust = 0.5f*(motor1 + motor2);
      75      154103 :         yaw_thrust   = -(actuator[0] + actuator[1] + actuator[2] + actuator[3]) * 0.25f * thrust + (motor2 - motor1) * rotor_rot_accel;
      76      154103 :         roll_thrust  = (actuator[0] - actuator[2]) * 0.5f * thrust;
      77      154103 :         pitch_thrust = (actuator[1] - actuator[3]) * 0.5f * thrust;
      78      154103 :         break;
      79             :     }
      80             :     }        
      81             :     
      82             :     // rotational acceleration, in rad/s/s, in body frame
      83      308161 :     Vector3f rot_accel(roll_thrust * roll_rate_max,
      84      308161 :                        pitch_thrust * pitch_rate_max,
      85      308161 :                        yaw_thrust * yaw_rate_max);
      86             : 
      87             :     // rotational air resistance
      88      308161 :     rot_accel.x -= gyro.x * radians(5000.0) / terminal_rotation_rate;
      89      308161 :     rot_accel.y -= gyro.y * radians(5000.0) / terminal_rotation_rate;
      90      308161 :     rot_accel.z -= gyro.z * radians(400.0)  / terminal_rotation_rate;
      91             : 
      92             :     // air resistance
      93      308161 :     Vector3f air_resistance = -velocity_air_ef * (GRAVITY_MSS/terminal_velocity) / eas2tas;
      94             : 
      95             :     // scale thrust to newtons
      96      308161 :     thrust *= thrust_scale;
      97             : 
      98      308161 :     accel_body = Vector3f(0, 0, -thrust / mass);
      99      308161 :     accel_body += dcm.transposed() * air_resistance;
     100             : 
     101      308161 :     update_dynamics(rot_accel);
     102             :     
     103             :     // update lat/lon/altitude
     104      308161 :     update_position();
     105      308161 :     time_advance();
     106             : 
     107             :     // update magnetic field
     108      308161 :     update_mag_field_bf();
     109             : 
     110      308161 :     update_battery();
     111      308161 : }