Joint driving apparatus

A joint driving apparatus for generating a relative movement between first and second members on a joint, comprising,

• a linear motor including at least one stator part fixed to another one of the first and second members, a movable element movable with respect to the stator part in a movable direction and connected to the one of the first and second members to be moved with respect to the another one of the first and second members, and an electromagnetic coil device for energizing the stator part to be magnetized so that a magnetic field for urging the movable element in the movable direction with respect to the stator part is generated,
• wherein the stator part includes at least two pairs of magnetic poles, the at least two pairs are adjacent to each other in the movable direction, the magnetic poles of each of the at least two pairs face to each other through the movable element in a traverse direction perpendicular to the movable direction to generate the magnetic field passing the magnetic poles through the movable element, and a magnetic polar direction of one of the at least two pairs is opposite to that of another one of the at least two pairs adjacent to the one of the at least two pairs in the movable direction when the stator part is magnetized.