CONTROL OF DIGITS FOR ARTIFICIAL HAND

A digit mechanism for an artificial hand comprises: a lower digit (44) arranged to be rotatably coupled to a palm unit (12) of the artificial hand; an upper digit (48) rotatably coupled to the lower digit (44); a lower digit rotation mechanism (34, 46, 52, 58) for applying a moment to the lower digit (44) to rotate the lower digit (44) relative to the palm unit (12); an upper digit rotation mechanism (50, 54, 56) for applying a moment to the upper digit (48) to rotate the upper digit (48) relative to the lower digit (44); and a force balancing mechanism (60, 58) for mechanically adjusting the magnitude of the moment applied by the lower digit rotation mechanism (34, 46, 52, 58) and/or the upper digit rotation mechanism (50, 54, 56) in accordance with the magnitude(s) of outside forces resisting rotation of the upper digit (48) and/or the lower digit (44) in order to preferentially apply movement to the digit experiencing lower resistance to movement; wherein the force balancing mechanism is arranged to increase the force applied to rotate a controlled digit when a controlling digit experiences a greater resistance to movement than the controlled digit, and decrease the force applied to rotate the controlled digit when the controlling digit experiences a lesser resistance to movement than the controlled digit; wherein the lower digit rotation mechanism (34, 46, 52, 58) and upper digit rotation mechanism (50, 54, 56) are arranged to be mechanically actuated, in use, by a force applied from a single actuator at the palm unit (12).