Fig. 1.

Models of force representation. A: schematic illustration of the force applied by the haptic device during adaptation in the nondelayed (solid blue line) and delayed (solid beige line) conditions, using the same representative velocity trajectory (dotted gray line) in both conditions. B: the representation of nondelayed force (solid dark blue line) is modeled as a combination of position (Pos; dotted orange line) and velocity (Vel; dotted green line). C: possible representations of delayed force (solid brown line). Left: based on representation of position and delayed velocity (Delayed Vel; dotted dark blue line); right: based only on current state; position, velocity, and acceleration (Acc; dotted purple line).