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CENTER OF PRESSURE (COP) EXERCISE TRACKER

CHALLENGE

To create a series of research study exercises geared toward tracking the position of a patient's Center of Pressure (COP). A patient places their left or right foot in a platform mounted to a multi-axis force transducer capable of providing force in x,y and z planes and moments in x, y and z planes. Based on patient movement, a corresponding translated COP value was to be displayed on a computer screen, in conjunction with a series of reaching and maintaining exercises.

SOLUTION

All voltages (supplied via an amplifier specifically designed for the load cell) were fed directly into a low cost, multi-analog input data acquisition card. Via a series of transfer functions, each voltage was translated to a center or pressure value displayed on a single X-Y chart. Given the design of the platform (mounted on the transducer), side-to-side foot movements translated to +/- x-direction cop position while front-to-back food movements translated to +/- y-direction cop position.

The user interface consisted of a patient calibration interface, troubleshooting interface, an exercise configurator utility and the actual 'runtime' interface displayed during an actual exercise. Due to the fact that not all patients are going to exhibit the same range of motion, a calibration interface was incorporated allowing but the user and the patient to easily calibrate the visible axes on the COP plot to correspond directly to that patient's limited range of motion. A troubleshooting interface was provided allowing the user to chart the individual (raw) voltages sampled directly from the load cell's amplifier box. The 'exercise configurator' is a utility that allows the user to choose from a series of reaching and stability exercises for the patient. Each exercise consists of its own unique set of parameters (i.e. a patient must 'reach' a target by controlling the position of their COP - or a patient must 'maintain' their COP within a set of moving boundaries). Once configured, the exercise could be started/stopped/restarted/re-configured at the user's discretion.

During runtime, all information about COP position, configured exercise, moving target position, etc are all streamed to disk, allowing the user to recreate the exercise and perform any analysis necessary for the purposes of the study.