Figure 3: Information transmission loop. SSVEP signals are evoked in brains when subjects pay their attentions to one of the flickering circles. The robot judges motion intentions of subjects through recognizing the flickering source of SSVEP signals and is triggered to deliver predefined training. Haptic feedback ascends to brains when ankles rotate following the robot, and visual feedback of ankle rotation ascends to brains when the hammer moves in virtual reality training circumstance.