Table 1.

Overview of recent lower-limb rehabilitation robots.

Groups	Devices	Researchers	Actuated DoF	Driving modes	Control strategies	Training modes
	Lokomat [101]	Zurich Switzerland	Two-leg DoFs	Motor drive	Position control Patient-cooperative strategy Posture control	Passive mode Active assist mode
	LokoHelp [16]	Woodway & LokoHelp Group	Two-leg DoFs	Treadmill drive, standalone driving device not required	Trajectory tracking control	Passive mode Active assist mode
Treadmill-based exoskeleton robots	ALEX [17]	Banala and Aqrawal et al. from University of Delaware, US	Seven DoFs for translations and rotation of a leg	Motor drive	Assist-as-needed control	Active mode
	Lopes [18, 19]	Reneman et al. From university of Delaware, US	Three rotational DoFs in each leg	SEA (series elastic actuator) drive	Impedance control	Active mode Active assist mode
	AAFO [20]	Seoul and Korea from Yonsei University	Two motion DoFs for ankle joint	SEA (series elastic actuator) drive	Force/impedance control	Active mode
	KAFO [21]	The Department of Mechanical Engineering of the Ottawa University	Free motion DoFs in sagittal plane for ankle and knee	No driver, using the location of mechanical structure and spring to provide tailwind	Force control	Active assist mode
Leg orthoses exoskeleton robots	HAL [22]	University of Tsukuba, Japan	Full-body exoskeleton for arms, legs	Motor drive	Autonomous control Automatic mixture control	Active assist mode
	BLEEX [23, 24]	Kazeroom et al. from University of California, US	Seven DoFs for each leg in hip, knee, and ankle joints	Hydraulic drive	EMG signal control Force control	Passive mode
	Rutgers ankle [25]	Girone et al. of Rutgers University	Six DoFs ankle and foot based on a Stewart platform	Pneumatic drive	Impedance control Force control	Active mode Passive mode Active resist mode
Platform-based end-effector robots	ARBOT [26, 27]	Saglia et al. from Istituto Italiano di Tecnologia, Italy	Two ankle DoFs in plantar/dorsiflexion, inversion/eversion	Motor drive	Position control	Passive mode Active assist mode Active resist mode
	Parallel ankle robots [28, 29]	Xie et al. from the University of Auckland New Zealand	Three ankle DoFs provided by 4-axis parallel robot	Motor drive	EMG-based evaluation and adaptive control	Active mode Passive mode
	Gait Trainer GTI [30]	The Free University Berlin, Germany	Two footplates for foot/leg movement	Motor drive	Trajectory tracking control	Passive mode Active mode
Footplate-based end-effector robots	Haptic Walker [31]	Hesse et al. from Charite University Hospital, Germany	Arbitrary movement DoFs for two feet	Motor drive	Trajectory tracking control	Passive mode Active mode
	G-EO Systems [32]	Reha Technology AG, Switzerland	Two footplates for walking and climbing DoFs	Motor drive	Position control Trajectory tracking control	Active assist mode