AP_Motors: tricopter apply diffential thrust in forward flight

libraries/AP_Motors/AP_MotorsTri.cpp

@@ -323,11 +323,29 @@ void AP_MotorsTri::thrust_compensation(void)
 /*
   override tricopter tail servo output in output_motor_mask
  */
-void AP_MotorsTri::output_motor_mask(float thrust, uint8_t mask)
+void AP_MotorsTri::output_motor_mask(float thrust, uint8_t mask, float rudder_dt)
 {
     // normal multicopter output
-    AP_MotorsMulticopter::output_motor_mask(thrust, mask);
+    AP_MotorsMulticopter::output_motor_mask(thrust, mask, rudder_dt);
 
     // and override yaw servo
     rc_write(AP_MOTORS_CH_TRI_YAW, _yaw_servo->get_trim());
 }
+
+float AP_MotorsTri::get_roll_factor(uint8_t i)
+{
+    float ret = 0.0f;
+
+    switch (i) {
+        // right motor
+        case AP_MOTORS_MOT_1:
+            ret = -1.0f;
+            break;
+        // left motor
+        case AP_MOTORS_MOT_2:
+            ret = 1.0f;
+            break;
+    }
+
+    return ret;
+}

libraries/AP_Motors/AP_MotorsTri.h

@@ -47,8 +47,13 @@ public:
     // output a thrust to all motors that match a given motor
     // mask. This is used to control tiltrotor motors in forward
     // flight. Thrust is in the range 0 to 1
-    void                output_motor_mask(float thrust, uint8_t mask) override;
-    
+    // rudder_dt applys diffential thrust for yaw in the range 0 to 1
+    void                output_motor_mask(float thrust, uint8_t mask, float rudder_dt) override;
+
+    // return the roll factor of any motor, this is used for tilt rotors and tail sitters
+    // using copter motors for forward flight
+    float               get_roll_factor(uint8_t i) override;
+
 protected:
     // output - sends commands to the motors
     void                output_armed_stabilizing() override;