Design of Onboard Avionics Based on Commercial Off-the-Shelf Parts for TianQi-2 Nanosatellite

With the development of modern small satellite technology, short development cycles, low cost, and high reliability have become trends in the era of New Space. To achieve the above goals, an integrated centralized architecture of onboard avionics for an internet of things CubeSat was proposed, and CAN, I2C, and 1-wire buses were employed for telemetry collection and command sending. The implementation of onboard computers (OBCs) and the power conditioning and distribution unit (PCDU) was introduced based on the PC104 industrial standards. An arbitration switching strategy between the primary and backup OBCs was proposed so that the primary OBC had priority to be on duty. Over 98% of commercial off-the-shelf (COTS) parts were used to decrease costs, so a procedure for COTS part selection and a qualified method were presented for reliable application. The onboard avionics, including OBC and PCDU, were developed in six months, and the satellite has been in orbit for more than three years and still works well. The reliability of the onboard avionics developed using the philosophy of New Space is demonstrated by the three-year flight in orbit.