Tham khảo tài liệu 'aerial vehicles part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 542 Aerial Vehicles PC-104 processor board has only two serial ports which are not enough for collection data from more than two sensors that communicate with serial port. As a result a serial port expender is packed with the main CPU board providing RS-232 485 communications. In order to control the Futaba model helicopter servos a PWM generation board is needed. Take price and reliable as consideration DSP board is chosen to generate 5-channel PWM signal as well as capture the PWM signal encoded by remote controller when the system run at manual mode. Such a design is to ensure that the system can run independently at manual mode which the close loop of the servo control is not through PC-104 processor except for receiving the commands of servos from serial port. Li-Ion battery serves as a power supplement to the overall onboard system such as flight computer system sensors communication units and servos through DC-DC converter. Eurotech ACS DC-DC converter is mounted to meet the system design requirement of converting a 9-40V DC input voltage to multi-voltage power outputs including 5V and 12V with overload protection. An optional onboard microprocessor monitors the temperature of the module and protects it by turning the module off when temperatures exceed 85 centigrade-degree. The power supplement of the overall avionics system as well as five servos that control the helicopter is powered by a Li-Ion battery pack which has the capacity of 78WH at the output of 19V. QNX Real-Time Operation System To our flight control system a real-time operation system RTOS is required for the onboard computer system. After carefully consideration and comparison QNX Neutrino RTOS is selected as the operation system which is ideal for embedded real-time applications. It can be scaled to very small size and provides multitasking threads priority-driven preemptive scheduling and fast context-switching - all essential ingredients of an embedded real-time system. The .
