岡田 達明

Digital Electronics and Optical Navigation Camera (DE-ONC) is an edge computing node of the asteroid probe HAYABUSA2. DE-ONC was developed to provide real-time image recognition performance for optical navigation. Lightweight, low power consumption and miniaturization are realized to overcome resource restrictions. It also satisfies high reliability and safety requirements of HAYABUSA2 missions. There are static and dynamic requirements for reliability and safety. The former increases reliability by adding redundancy combining the concept of functional distribution and time-division redundancy to meet resource constraints. Functional distribution mode, standby redundancy mode and hot redundancy mode were realized with the same device configuration. The real-time performance of optical navigation exploiting image recognition functions of the unit was demonstrated through the interplanetary cruising phase, as well as touch down to and taking off from the asteroid Ryugu. DE-ONC is always required to operate in the critical operation phase. In addition to that, it must always satisfy latency requirements to complete processing within a predetermined duration and to guarantee hard real-time performance. In order to satisfy these requirements, the image processing unit of DE-ONC adopts a unified language processing system and a distributed memory model with reference to a parallel inference machine, which is a so-called the second generation artificial intelligence technology. Its image processing module integrates a radiation hardened micro-controller unit (MCU) and field programmable gate arrays (FPGAs) with the language processing system and the distributed object model. We report the evaluation result of reliability and safety with real-time performance of the unit's architecture.

<p>This report deals with the improvement of wire-sawing performance in vacuum by applying vibration to the saw wire. The performance of wire-sawing in vacuum has been investigated for future lunar and planetary explorations. Nickel fixing abrasives adhered on a rock specimen in vacuum and the abrasives slipped on it. Consequently, the rock was hardly cut. In the prototype for a high normal load, the cutting performance was investigated both in air and vacuum. The cutting amount was linearly increased under a high normal load even in vacuum. On the other hand, it was found that the saw wire vibrated due to fluctuating tension. The vibration of a tool generally accelerates the removal rate. In the previous machine with a flexural roller guide which natural frequency is 1820 Hz, the vibration of the saw wire at a frequency of 2100 Hz was excited to improve the performance. The cutting depth was proportional to the number of strokes even under a low normal load.</p>