Three-dimensional dynamical measurement of upper limb support during paraplegic walking

Functional electrical stimulation (FES) has been employed in paraplegic rehabilitation to resume their walking ability. However, there is less quantitative assessment method of FES walking efficiency and rehabilitation progress. This paper presents a new dynamical measurement of upper limb support force during paraplegic walking, which can be used to calculate the 3-D handle reaction vector (HRV). HRV may provide an assessment of FES-assisted efficiency. With a series of tests, the measurement accuracy, nonlinearity, and crosstalk of the designed system are testified. The force measurement error is found below 1.01%, while nonlinearity and crosstalk are less than 2.90%, and 3.19%, respectively. This means that the implemented walker system is reliable for the measurement of HRV during FES-assisted walking. A clinical trial is performed with a paraplegic subject. With the monitoring of FES-assisted walking, the downward component of HRV is found to decrease, implying the decreasing force generated from lower limb. The decrease slope in downward load curve can indirectly indicate the FES efficiency change during walking. The experiment and clinical trial results show that a 3-D dynamical measurement system is successfully accomplished to indirectly assess FES efficiency of lower limbs using quantitated forces applied by the upper limbs of paraplegic patients.