OBJECTIVE Balance between flexor and extensor muscle activity is essential for optimal function. The purpose of this pilot study was to compare the relationship between maximum finger flexion force and maximum finger extension force in women with rheumatoid arthritis and healthy women. METHODS Twenty healthy women (median age 61 years) and 20 women with rheumatoid arthritis (median age 59.5 y...

Cyclic isometric finger-force patterns established using visual feedback show systematic drifts when the feedback is removed. Force changes at multiple time scales and in opposite directions have been reported. For further characterization of these drifts, healthy subjects produced isometric, cyclic finger force with and without visual feedback at various initial amplitudes and frequencies. We ...

Introduction: Hand and wrist stability are critical for optimal upper extremity function. Instability occurs when injury or a pathological condition alters balance, typically in the basketball players and handball players. Injury also can occur whenever the ligaments are subjected to tensile forces that exceed their physiological capacities. For example, thumb is stable in ext...

This paper presents the Function Approximation Technique (FAT) based adaptive impedance control for a robotic finger. The force based impedance control is developed so that the robotic finger tracks the desired force while following the reference position trajectory, under unknown environment position and uncertainties in finger parameters. The control strategy is divided into two phases, which...

Finger enslaving is defined as the inability of the fingers to move or to produce force independently. Such finger enslaving has predominantly been investigated for isometric force tasks. The aim of this study was to assess whether the extent of force enslaving is dependent on relative finger movements. Ten right-handed subjects (22-30 years) flexed the index finger while counteracting constant...

In an overarm throw, as the hand opens and the ball rolls along the fingers, the ball exerts a back force on the fingers. Previous studies suggested that skilled throwers compensate for this back force by producing an appropriate finger flexor torque to oppose the back force, but it was unclear how this is controlled by the CNS. We investigated whether the increase in finger flexor torque is ti...

A force estimation model using motor current signals was deduced in this paper for a tendon-driven prosthetic finger grasping objects with its distal phalanx. Models of the prosthetic finger were first established. As driving moment of each joint could be calculated form motor current, stable grasping force of the finger could be calculated by its statics mechanic model, that is, the grasping f...

Physical conflicts tend to escalate. For example, as tit-for-tat exchanges between two children escalate, both will often assert that the other hit him or her harder. Here we show that, in such situations, both sides are reporting their true percept and that the escalation is a natural by-product of neural processing. Six pairs of naı̈ve participants took part in a tit-for-tat experiment. Each m...