An exoskeleton includes a first support, a second support, and a joint connecting the first and second supports. An actuator causes relative rotation between the first and second supports at the joint. The actuator includes a motor, a ball screw, a ball nut, and a yoke. The motor causes translation of the yoke via the ball screw and the ball nut. In some embodiments, the actuator further includes a roller and a joint cam having a track. Translation of the yoke causes movement of the roller within the track, and movement of the roller within the track causes rotation of the joint cam. In other embodiments, the actuator further includes a linkage and a joint crank. Translation of the yoke causes movement of the linkage, and movement of the linkage causes rotation of the joint crank. Rotation of the joint cam or the joint crank causes relative rotation between the first and second supports.