A highly integrated UAV avionics system 8 Fourth Street PO Box 1500 Hood River, OR (541) phone (541) fax CCT@gorge.

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1 A highly integrated UAV avionics system 8 Fourth Street PO Box 1500 Hood River, OR (541) phone (541) fax CCT@gorge.net Bill Vaglienti Ross Hoag April 10, 2003

2 Table of contents 1 Introduction Features Components of the Piccolo avionics system CPU Sensors Servo drivers Navigation Datalink Payload interface Expansion Groundstation Development environment Software environment Design environment Hardware in loop simulation...6 A highly integrated UAV avionics system Page 1

3 1 Introduction The number of applications for unmanned aircraft is large, and growing each year. The aircraft that already exist and those that are on the drawing board run the gamut of aircraft size and configuration; from enormously complicated and expensive vehicles like Teledyne Ryan's GlobalHawk, all the way down to tiny miniature air vehicles (MAVs) which weigh less than four ounces. The most potential for market growth is in small to medium sized vehicles; large enough to carry a useful sensor payload, but small enough to be simple to deploy and relatively inexpensive. Vehicles such as the DragonEye (2kg), the Aerosonde (13kg), and countless university and government research projects fit in this group. Each requires a sophisticated avionics package capable of autonomously flying and navigating the aircraft, as well as interfacing to payloads and communications systems. The majority of these aircraft use custom avionics that were developed by the aircraft manufacturer for their specific application. This doesn t have to be true any longer: Cloud Cap has developed a novel avionics package, the Piccolo, targeted for small unmanned aircraft. Piccolo is a leap forward from existing systems because it is a complete integrated avionics system, including avionics hardware and software, ground-station hardware and software, and a development and simulation environment. It is sophisticated and flexible enough to be used in many systems where hitherto only custom avionics were capable of meeting the requirements. 2 Features Exceptional integration and processing power from the MPC555 main processor. Small size: 4.8 x 2.4 x 1.5 Weight 212 grams (7.5oz) with radio, GPS and enclosure. 90 grams (3.1oz) without radio and enclosure. 3-axis rate and acceleration measurements for controlling low inertia and unstable platforms. Deadman s switch for safety. Expandable using the external interface or daughter board connector. Complete hardware integration including sensors, datalink, and servo drivers. Wide range of software support, including complete end-user programmability. Reference software design for ground station and simulation tools. Fully autonomous or pilot in the loop operation. Attitude independent installation. A highly integrated UAV avionics system Page 2

4 (5.5-20) Vin Input Protection Servo Power Deadman switch Refresh 44 pin filtered sub D 5V out 7 User defined TPUs Servo, Serial, I/O, Timing 5 PWM Outputs Servos RS232 I/O ports CAN Transceivers CAN A Dual CAN Interface CAN B SPI Optional Daughter Board Interface Connectors Power Supplies 5V 3.3V 3VA 5VA Monitor MPC555 40MHz Embedded Power PC with 448K Flash, 26K SRAM and a host of integrated peripherals BDM Port Interface Bus TPUs x5 10bit AtoD Inputs x8 External Trigs x2 Up to 2 Mbytes Burst SRAM MHX-910/2400 Datalink Radio Daughter Board Serial Serial/PPS Motorola M12 GPS Daughter Board SPI 16 Bit AtoD 115KPa Barometric Altimeter 10 Bit Inputs Amplifiers and 2nd order LPFs Temp Gyro X Gyro Y Dual Axis Accel 4KPa Airspeed Sensor Dual Axis Accel Gyro Z Plugin Daughter Board Figure 1. Piccolo block diagram 3 Components of the Piccolo avionics system 3.1 CPU The heart of Piccolo is the advanced MPC555 microcontroller. This is a new breed of automotive microcontroller based on the popular PowerPC architecture. The MPC555 marries an enormous array of interfaces to a powerful RISC engine that delivers 40Mhz PowerPC operation, including hardware floating point 3.2 Sensors Inertial sensors Piccolo features three Tokin CG-16D rate gyros and three ADXL202 accelerometers, which combined with its enormous CPU, horsepower gives Piccolo the ability to control a wide range of aircraft; run sophisticated filters; and allow installation in any attitude. A highly integrated UAV avionics system Page 3

5 3.2.2 Air data Piccolo includes a dual ported mpxv kPa dynamic pressure sensor, a absolute ported mpx4115a barometric pressure sensor, and an air temperature sensor. Together these sensor provide the ability to measure true air speed and altitude. These sensors are used as inputs to airspeed and altitude control loops. 3.3 Servo drivers Piccolo includes 10 servo outputs. These outputs are geared for model aircraft servos, which require pulse-width modulated signals, and 4-6 volt power. Alternatively some servo systems use a CAN bus to provide the servo signals. Piccolo includes two independent CAN buses. In either case the servo power supply is isolated from the main logic power supplies so that transient servo loading doesn t disable core system functions. 3.4 Navigation Navigation is accomplished by using a GPS to generate position and groundspeed, and then use that information to generate a turn rate command to the autopilot. The navigation algorithm in Piccolo follows the great circle path defined by waypoints in a stored flight plan. The flight plan can be updated while in flight GPS Piccolo uses the Motorola M12 GPS to provide its basic groundspeed and position. The M12 is differential capable, and Piccolo will supply it with any DGPS corrections received over the datalink. The Piccolo ground station is capable of generating these corrections using its own M Winds Piccolo can generate an estimate of winds aloft each time the aircraft turns by fitting true airspeed against GPS groundspeed. The wind estimate is useful since it enables an intelligent selection of heading when the wind speed exceeds the flight speed of the aircraft. 3.5 Datalink Piccolo includes a sophisticated datalink which is built on the MHX 910/2400 radio modem from Microhard Systems Inc. The datalink has up to 40Kbaud of throughput and is used for command and control, autopilot telemetry, payload data transfer functions, differential GPS corrections uplink, and pilot in the loop modes. The datalink architecture allows multiple aircraft to be controlled from one groundstation. 3.6 Payload interface An unmanned aircraft is only as useful as its payload. Accordingly Piccolo provides several means of connecting to payloads, including CAN, asynchronous serial, and discrete i/o. Data received from the payload(s) can be downlinked over the main datalink and demuxed by the operator interface. A highly integrated UAV avionics system Page 4

6 3.7 Expansion In addition to the interfaces available on the external connector Piccolo includes two daughter board connectors for user-defined applications. These connectors provide analog, SPI, timing, serial, and CAN methods of attaching hardware. 4 Groundstation Piccolo s groundstation is based upon the same hardware that makes up the avionics package. It manages the communication link to one or more avionics systems, interfaces to the pilot in the loop console, and provides a command and control stream to the operator interface PC. 5 Development environment The development environment is the set of tools which allows the vehicle designer to configure the avionics and software to accommodate the specific application. The tools that make up the development environment include: Avionics hardware, with built-in debugging and communication resources. Software compiler/debugger and driver source code. Control systems design and analysis tools. Auto-code generation tools for control systems and state machines. Aircraft simulation model. Hardware in loop simulation tools. While there are many small avionics systems available, few provide all the tools listed above. Piccolo is novel in part because the development environment was designed in from the beginning. 5.1 Software environment Piccolo includes built-in software which will be suitable for many applications, however for those applications that require fine control over the software it is completely end-user programmable and debuggable. Piccolo provides an interface for the on-chip debugging tools (Motorola BDM) and communications and i/o lines which can be used for debug. In addition Piccolo was designed to work with Metrowerks development tools to take full advantage of modern software design capabilities. A real time operating system and drivers for the on-board hardware are available for the Piccolo, both in source and compiled form. Using these drivers system designers can take full advantage of Cloud Cap's expertise to reduce their development time. 5.2 Design environment In recent years new design tools for control systems have come to maturity. The popular Matlab environment with its controls simulation package Simulink, has been augmented by the addition of autocode tools Real-Time-Workshop (RTW) and Stateflow. Using these tools control system designers can graphically model physical plants and design control laws and state machines. The resulting designs can then be automatically coded in C using RTW, compiled using the software A highly integrated UAV avionics system Page 5

7 environment, and downloaded to the target system. Piccolo has more than enough CPU muscle to run complicated autocoded algorithms. Indeed the basic control software that comes with Piccolo was designed in exactly this fashion, and Cloud Cap has made the design available to developers. 5.3 Hardware in loop simulation Hardware-in-loop (HIL) simulation is a cornerstone of unmanned aircraft development. Well designed simulators allow the aircraft control laws and mission functionality to be tested without risking hardware in flight test. Although HIL simulation can not replace flight testing, it measurably reduces the likelihood of failure by detecting bugs and deficiencies in the lab. To facilitate this vital (and typically difficult) function the Piccolo developers kit includes a hardware in the loop simulator which can be used to test the performance of a Piccolo implementation. The HIL simulator is based upon the external CAN interface. When in simulation mode Piccolo sends control surface signals and receives sensor inputs from the CAN interface. A PC with a CAN interface card running the HIL simulation software completes the necessary hardware. A highly integrated UAV avionics system Page 6