Inertial Compensation in Moving Platform
When load cells are located directly underneath a force plate, moving the platform will introduce inertial artifacts in the force measurements of the load cell. To compensate for these errors, we've developed a simple, accelerometer-based technique that assumes a linear relationship between force and acceleration. Artifacts due to inertia and gravity are estimated from accelerometer signals and subtracted from measured forces and quantified by the reduction in the root-mean-square (RMS). The method was tested experimentally on a 2 degree-of-freedom (DOF) instrumented force treadmill capable of mediolateral translation and sagittal pitch. Mass coefficients from one trial of random movements was used to compensate for inertial errors of another trial containing different random movements. At 6 Hz bandwidth, it was found that the compensation method was capable of reducing force and moment signals by 85.34% and 69.06%, respectively. At higher bandwidths of 20 Hz, the force and moments signals were still significantly reduced by 70.07% and 36.67%, respectively. It was concluded that the compensation method is capable of reducing inertial artifacts in force and moment signals to a more reasonable level, though investigation into more appropriate instrumentation is needed for the technique to be more successful.