SITL: added tricopter simulator

libraries/SITL/SIM_Frame.cpp

@@ -84,6 +84,13 @@ static const Motor octa_quad_motors[] =
     Motor(AP_MOTORS_MOT_8, -135, AP_MOTORS_MATRIX_YAW_FACTOR_CW,  6)
 };
 
+static const Motor tri_motors[] =
+{
+    Motor(AP_MOTORS_MOT_1,   45, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 1),
+    Motor(AP_MOTORS_MOT_2,  -45, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 3),
+    Motor(AP_MOTORS_MOT_4,  180, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 2, AP_MOTORS_MOT_7, -45, 45, -1, 0, 0),
+};
+
 /*
   table of supported frame types
  */
@@ -96,7 +103,8 @@ static Frame supported_frames[] =
     Frame("hexa",      6, hexa_motors),
     Frame("hexax",     6, hexax_motors),
     Frame("octa",      8, octa_motors),
-    Frame("octa-quad", 8, octa_quad_motors)
+    Frame("octa-quad", 8, octa_quad_motors),
+    Frame("tri",       3, tri_motors)
 };
 
 void Frame::init(float _mass, float hover_throttle, float _terminal_velocity, float _terminal_rotation_rate)

libraries/SITL/SIM_Motor.cpp

@@ -34,5 +34,21 @@ void Motor::calculate_forces(const Aircraft::sitl_input &input,
     rot_accel.y =  radians(5000.0) * cosf(radians(angle)) * motor_speed;
     rot_accel.z = yaw_factor * motor_speed * radians(400.0);
     thrust(0, 0, motor_speed * thrust_scale); // newtons
+    if (roll_servo >= 0) {
+        float roll = constrain_float(roll_min + (input.servos[roll_servo]-1000)*0.001*(roll_max-roll_min), roll_min, roll_max);
+        Matrix3f rotation;
+        rotation.identity();
+        rotation.rotate(Vector3f(radians(roll), 0, 0));
+        rot_accel = rotation * rot_accel;
+        thrust = rotation * thrust;
+    }
+    if (pitch_servo >= 0) {
+        float pitch = constrain_float(pitch_min + (input.servos[pitch_servo]-1000)*0.001*(pitch_max-pitch_min), pitch_min, pitch_max);
+        Matrix3f rotation;
+        rotation.identity();
+        rotation.rotate(Vector3f(0, radians(pitch), 0));
+        rot_accel = rotation * rot_accel;
+        thrust = rotation * thrust;
+    }
 }