This invention provides a portable two-pillow system that gently elevates the lumbar, thoracic and cervical spine to promote posture, alignment and pain relief from either a seated, reclined or horizontal position. The parallax barrier may be formed with a liquid crystal display of a normally black mode of transmission. The cartilage map can be correlated to a movement pattern of the joint to assess the affect of movement on cartilage wear. In some embodiments, the electrical components carried are the same, and in other embodiments, the electrical components carried in the first row differ from the electrical components carried in the second row. Upon the occurrence of a triggering error, the test modules associated with the test module identifiers are executed in a reverse order to that which the test module identifiers were added to the error stack, effecting a structured state teardown. It is proposed that the mechanical state variable be determined by a predictor element that contains a model of the drivetrain andor the internal combustion engine.