Table 3.

Overview of training modes for rehabilitation robot.

Training modes	Characteristics	Representative works
Passive mode	The robot helps the patient track the predetermined trajectory through repeated tracking control for passive training.	Ankle robot and gait orthosis [90–92] Gait Trainer (GTI) [30] LOPES [93]
Active mode	When the patient has a certain initiative, the rehabilitation robot will change its trajectory or assistance force.	AAFO [20] LOPES [93] ALEX [17]
Active assist mode	A kind of “active” mode. The patient does not need any help to move the limb. When the threshold value reaches a certain standard, it will trigger the robot.	HAL [22] KAFO [21] G-EO Systems [32]
Active resist mode	A kind of “active” mode. When the patient moves the limb, the robot provides resistance to make the exercise more challenging.	ARBOT [94, 95] Rutgers ankle [25]