The purpose of this paper is to describe a system for the rapid spot check of the accuracy of stabilometric platforms used in clinical posturography and, if needed, for estimating a recalibration matrix. It is based on a simple mechanical device which can be applied to any stabilometric platform; it consists of a ballast and a rotating mass which can generate a spiral-shaped training set of posturographic data. A software package has been developed whose purpose is to estimate a calibration matrix and to provide a figure of merit for the calibrated system. The data analysis is organized into two phases: a preliminary global phase, which uses the covariance matrix of the training set, and a refinement, iterative phase, which exploits the equation of the spiral. The characteristic features of the proposed system are: 1) it uses dynamic, not static loading, 2) loading is not applied manually, 3) it uses distributed, not point loads, 4) there is no need to bolt the system to the platform. Although these features are found, separately, in different prototypes described in the literature, their combination can only be found in the proposed system. Moreover, while most systems in the literature are intended for gait analysis, the proposed one is specifically designed for posturography.