“…The estimator design involves decisions on: (i) the structure (sensor number and locations), and (ii) the kind of (EKF, Luenberger, Geometric, etc) algorithm. In the distillation column estimation field: (i) the EKF has been, by far, the most widely employed and accepted algorithm, (ii) the sensor structure has been decided with heuristics (Oisiovici and Cruz, 2000) or observability measures (van der Berg et al 2000;Singh and Hahn, 2005), (ii) only in a few studies (Alonso et al, 2004;Bian and Henson 2006;Venkateswarlu and Kumar, 2006;Kadu et al, 2008) the measure-based sensor location results have been tested with estimator functioning and is not clear to what extent the results depend on tuning. In principle, the resolution of this drawback requires a unified framework to address the algorithm, sensor location, and tuning aspects.…”