A computer model of the human arm: Predictive biomechanics for the theradrive rehabilitation system

Here we describe the ongoing development of a unique computer model to simulate the upper-limb during sinusoidal tracking activity on the TheraDrive, a 1 degree of freedom (DOF) haptic stroke rehabilitation system. The model predicts longitudinal muscle forces while simulating TheraDrive activity to better understand the physiological changes (e.g. muscle dynamics) that arise from stroke and subsequent rehabilitation. Initial validation of the model simulated five patients without implementing stroke impairment. Validation revealed that the model´s performance was invariant of the patient´s stroke level (reflecting the lack of stroke emulation in silico), while suggesting the model may use multiple strategies to complete the TheraDrive activity task. This work sets the stage for in-depth analysis of the biomechanical implications of stroke on robotic rehabilitation. Next steps include simulating different modes of activity on the TheraDrive and further validating the model by measuring muscle activations during real-world activity.