1.  Stability
2.  Features
3.  Navigation and Mission Control
4.  Block Diagram
5.  UAV, RPV and PIC Flight Modes
6.  Autonomous Takeoff and Landing
7.  Data Logging
8.  AP50 AutoPilot Operator Interface
9.  Ground Control Station (GCS)
10. Electric Flight
11. About UAV Flight Systems

The AP50 stabilizes a UAV using its integrated roll, pitch, and yaw rate gyros, a two-axis accelerometer, a barometric altimeter and a pitot airspeed sensor, in addition to GPS-derived altitude and speed information. The control laws used by the AP50 are sophisticated and offer a wide choice of control philosophies to the user. The sophistication of the AP50 enables it to control airframes that are difficult to fly manually.
 

• Small, lightweight and low cost
• Three-axis sensor module with roll, pitch, and yaw gyros
• Barometric altimeter, pitot airspeed sensor, and two-axis accelerometer
• Onboard GPS receiver
• Flexible communication ports support operator setup and in-flight retasking
• Sophisticated flight stability model
• Two data-logging A/D channels available for instrumentation
• Suitable for both gasoline-powered and electric-powered radio controlled (RC) aircraft
• Weight: 50 grams (1.8 oz)
• Size: 144 mm (5.7") 47mm (1.9") 28 mm (1.1")
• Power: 150 mA @ 5.3 - 8 volts

The user may specify up to 24 waypoints, each with a speed and altitude setting to that waypoint. The UAV will proceed from one waypoint to the next at the programmed speed and altitude. Upon arrival at any waypoint the UAV may enter a holding pattern, change mission servo positions (3) or digital outputs (3),  providing a high degree of flexibility in controlling onboard systems. Any number of events may be executed upon arrival at a waypoint. The RC receiver may be disabled, then re-enabled upon return home to prevent unauthorized interference during a mission.

The AP50 AutoPilot system will interface to any standard PPM or PCM 5-channel RC receiver, and control up to five servos (ailerons, elevator, throttle, rudder, flaps). In UAV mode, all navigation and stability control is managed by the AP50. In RPV (Remotely Piloted Vehicle) mode, the pilot can assume manual navigation control, with the autopilot providing airframe stability. In RPV mode, UAV mission retasking is also possible (see Ground Control Station section). In PIC Pilot In Control) mode the pilot has direct control over the servos, just like normal radio controlled flying. PIC mode is sometimes referred to as RC mode.

Autonomous takeoff consists of the acceleration phase followed by the initial climb-out phase. Total management of the control law algorithms is allowed during each state to support any type of takeoff, ranging from conventional runway to catapult launch. Landing is also an independent state, allowing specific parameters to be selected for maximum stability and slowest airspeed. Landing under autonomous control consists of specifying an engine shutdown event upon arrival at the landing location and entering a holding pattern over the selected landing site at minimum airspeed. Alternatively, a mission servo may activate a parachute recovery system. Normal takeoff and landing is possible using PIC mode.

A two-channel 8-bit A/D digitizes user instrumentation for data logging. Data is logged once every second, providing over one hour of logged data. Additional navigational data (altitude, speed) is also available that may be selected for data logging. A PC is used to download and display user and flight data after ouchdown.

The AP50 Flight Processor (FP) and Mission Processor (MP) each have a built-in operator interface for autopilot setup and data retrieval. This simple command line interface is accessed using a computer with a terminal emulator program (such as HyperTerminal on a Windows PC). The computer is connected via RS-232 serial cable to either the FP port or MP port on the AP50.

An important requirement for UAVs is the ability to change navigation and mission information during flight re-tasking). The AP50 incorporates a dedicated GCS port for communication via wireless RF datasets to a computer running GCS software. Navigation and flight data can be continuously downlinked during flight. The GCS port also supports direct connection to a computer for mission setup on the ground. GroundPilot from UAV Flight Systems is a Windowsbased ground control station product for the AP50 (and AP40) . GroundPilot provides a graphical display for UAV status, map integration for displaying UAV location and waypoint entry, and command functions for sending and retrieving information from the autopilot.

The AP50 is electric-flight qualified with its ability to shut down a UAV motor under user-defined low battery conditions. This feature prevents the battery from being drawn perilously low, and the associated risk of power loss to the autopilot during flight.

We develop miniature, low-cost GPS-enabled autopilots specifically for the control of small Unmanned Aerial Vehicles. Our products have been carefully engineered to achieve the highest performance in a miniature, power conserving package. With a UAV Flight autopilot, designers can focus on the airframe and mission without worrying about the flight control system. UAV Flight Systems also offers complete UAV trainer/ demonstrator systems, and custom engineering services.