Visual Feedback of Object Motion Direction Influences the Timing of Grip Force Modulation During Object Manipulation

Analysis of grip forces during object manipulation

Superposition of Automatic and Voluntary Aspects of Grip Force Control in Humans during Object Manipulation

When moving grasped objects, people automatically modulate grip force (GF) with movement-dependent load force (LF) in order to prevent object slip. However, GF can also be modulated voluntarily as when squeezing an object. Here we investigated possible interactions between automatic and voluntary GF control. Participants were asked to generate horizontal cyclic movements (between 0.6 and 2.0 Hz...

Adaptive control of grip force to compensate for static and dynamic torques during object manipulation.

Manipulating a cup by the handle requires compensating for the torque induced by the moment of the mass of the cup relative to the location of the handle. In the present study, we investigated the control strategy of subjects asked to perform grip-lift movements with an object with center of mass located away from the grip axis. Participants were asked to lift the manipulandum with a two-finger...

Effect of fatigue on grip force control during object manipulation in carpal tunnel syndrome.

Eight subjects with carpal tunnel syndrome (CTS) (47.13 ± 7.83 years) and 8 matched controls (46.29 ± 7.27 years) manipulated a test object fitted with an accelerometer and force sensor, both before and after hand muscle fatigue. Grip force and object acceleration were recorded and used to calculate grip force control variables that included Grip Force Peak, Safety Margin, and Time to Grip Forc...

Friction, not texture, dictates grip forces used during object manipulation.

1. Three men and seven women, 25-40 yr of age, were asked to use the thumb and index fingers to grasp, lift, and hold the armature of a linear motor generating a 2.0-N opposing force (simulating an object weighing approximately 200 g) for 2 s. The surface in contact with the fingers was composed of smooth or polyamide plastic etched with 1.0-mm high Braille beads separated at 2.0- or 3.0-mm int...