This paper describes three approaches to enabling a severely computationally limited embedded scheduler to consider a small number of alternative activities based on resource availability. This paper considers the case where the scheduler is so computationally limited that it cannot backtrack search. The first two approaches precompile resource checks (called guards) that only enable selection of a preferred alternative activity if sufficient resources are estimated to be available to schedule the remaining activities. The third approach mimics backtracking by invoking the scheduler multiple times with the alternative activities. This paper presents an evaluation of these techniques on Mars mission scenarios (called sol types) from NASA’s M2020 Perseverance Rover where these techniques and analysis contributed to the design of the onboard scheduler.

本文介绍了三种方法，这些方法使受严格计算限制的嵌入式调度程序能够基于资源可用性考虑少量替代活动。本文考虑了调度程序在计算上受到限制以至于无法回溯搜索的情况。前两种方法预编译资源检查（称为防护），只有在估计有足够的资源可用于安排其余活动时，才可以选择首选的替代活动。第三种方法通过使用替代活动多次调用调度程序来模仿回溯。