推理理论一般分为确定性推理理论和不确定性推理理论。传统的卫星故障检测和诊断应用的是确定性推理。然而，在卫星故障检测和诊断的实践中，仅使用确定性推理是很难对某些故障进行检测和诊断的，因为这时需要合情推理和容错能力。不确定性推理理论可以满足此要求。目前，航天领域的许多专家和实际工作者正致力于应用不确定性推理理论检测和诊断那些用确定性推理无法检测和诊断的故障。不确定性推理理论包括诸如包含度理论、粗糙集理论、证据推理理论、概率推理理论、模糊推理理论等。笔者研究的卫星故障检测和诊断的三种新方法，分别应用了包含度理论、粗糙集理论和证据推理理论。

Generally, reasoning theory can be divided into certainty reasoning theory and uncertainty reasoning theory. Traditionally, certainty reasoning theory is used to detect and diagnose satellite faults. However, in practice, it is difficult to detect and diagnose some satellite faults automatically only by use of certainty reasoning theory. The reason is that detection and diagnosis of these faults requires reasonable reasoning and fault-tolerant capability, but certainty reasoning theory can not realize the capability. Fortunately, uncertainty reasoning theory can meet this requirement. Now, it is attracting attention of many researchers and practitioners in the space field all over the world that uncertainty reasoning theory is applied to detect and diagnose the satellite faults which can not be handled properly by certainty reasoning theory. Uncertainty reasoning theory includes several kinds of theories, such as inclusion degree theory, rough set theory, evidence reasoning theory, probabilistic reasoning theory, fuzzy reasoning theory, and so on. This paper introduces three new methods to detect and diagnose the satellite faults, in which inclusion degree theory, rough set theory and evidence reasoning theory of the uncertainty reasoning theory are used respectively.