Presents an algorithm for design of fault tolerant multi-sensor systems. The design is essentially based on some observability properties, which are the observability indexes and the pseudo-observability indexes. These properties are used in Hoblos et al. (2000) and Staroswiecki et al. (1999) to define minimal sensor sets (MSS) and pseudo-minimal sensor sets (PMSS). The paper introduces a definition of an equivalence relation between PMSS, which allows us to build sensor sub-sets classes (SSC). The design method is illustrated by an application example, which is automated truck platooning.