Effects of Tactile Sensitivity on Structural Variability of Digit Forces during Stable Precision Grip

Figure 1

Experimental setup, tactile conditions, and representative data. (a) The apparatus and posture for precision grip; (b) tactile conditions; and (c) force signals of the thumb and index finger from a representative subject. ① Force transducers were instrumented inside the shields. ② Fingertips were wrapped with polyethylene films. ③ and ④ Local coordinate systems for the thumb and index finger, respectively. Tactile conditions I: nondigit was blocked; II: only the thumb was blocked; III: only the index finger was blocked; and IV: both the thumb and index finger were blocked. The curves shown in (c) are the force components of the thumb and index finger in the x-, y-, and -axis with respect to the local coordinate systems.