Sensor-Based Assessment of Upper-Limb Motor Control in Children and Adults Using Two-Dimensional Circular Target Tracking

Objective, portable sensor-based assessment of human motion is vital for monitoring motor development and designing rehabilitation applications. This study investigated upper-limb motor characteristics during 2D circular target tracking across different age groups and speeds. Fifty-one participants were divided into three groups: lower elementary children, upper elementary children, and adults. Using a tablet- and stylus-based input device, suitable for human-computer interaction systems, participants tracked targets at three speeds. Each trial included target-visible and target-invisible segments to separately measure feedback- and feedforward-dominant errors, derived as a tracer error ratio. The results revealed similar error ratios for both child groups across all speeds, whereas adults exhibited lower ratios. As tracking speed increased, the tracer error ratio decreased in all groups, with only adults achieving a ratio below one at high speeds. These findings support the hypothesis that cerebellar motor models for position and speed control continue to develop from childhood into adulthood. The study concludes that this portable stylus-based approach serves as a practical digital metric for effective upper-limb assessment.