AP_ExternalControl: external control library for MAVLink,lua and DDS

Signed-off-by: Ryan Friedman <ryanfriedman5410+github@gmail.com>
Co-authored-by: Andrew Tridgell <tridge60@gmail.com>

libraries/AP_ExternalControl/AP_ExternalControl.cpp

@@ -0,0 +1,24 @@
+#include "AP_ExternalControl.h"
+
+#if AP_EXTERNAL_CONTROL_ENABLED
+
+// singleton instance
+AP_ExternalControl *AP_ExternalControl::singleton;
+
+AP_ExternalControl::AP_ExternalControl()
+{
+    singleton = this;
+}
+
+
+namespace AP
+{
+
+AP_ExternalControl *externalcontrol()
+{
+    return AP_ExternalControl::get_singleton();
+}
+
+};
+
+#endif // AP_EXTERNAL_CONTROL_ENABLED

libraries/AP_ExternalControl/AP_ExternalControl.h

@@ -0,0 +1,43 @@
+/*
+  external control library for MAVLink, DDS and scripting
+ */
+
+#pragma once
+
+#include "AP_ExternalControl_config.h"
+
+#if AP_EXTERNAL_CONTROL_ENABLED
+
+#include <AP_Math/AP_Math.h>
+
+class AP_ExternalControl
+{
+public:
+
+    AP_ExternalControl();
+    /*
+      Set linear velocity and yaw rate. Pass NaN for yaw_rate_rads to not control yaw.
+      Velocity is in earth frame, NED [m/s].
+      Yaw is in earth frame, NED [rad/s].
+     */
+    virtual bool set_linear_velocity_and_yaw_rate(const Vector3f &linear_velocity, float yaw_rate_rads)
+    {
+        return false;
+    }
+
+    static AP_ExternalControl *get_singleton(void)
+    {
+        return singleton;
+    }
+
+private:
+    static AP_ExternalControl *singleton;
+};
+
+
+namespace AP
+{
+AP_ExternalControl *externalcontrol();
+};
+
+#endif // AP_EXTERNAL_CONTROL_ENABLED

libraries/AP_ExternalControl/AP_ExternalControl_config.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <AP_Common/AP_Common.h>
+#include <AP_HAL/AP_HAL_Boards.h>
+
+#ifndef AP_EXTERNAL_CONTROL_ENABLED
+#define AP_EXTERNAL_CONTROL_ENABLED 1
+#endif
+
+