Figure 1.

Examples of robotic therapy devices using different types of assistance-based control algorithms. Examples of robotic therapy devices using different types of assistance-based control algorithms. Two of the first devices to undergo clinical testing, MIT-MANUS and Lokomat, initially used proportional position feedback control to provide assistance. Newer software for MIT-MANUS [55] (A) adapts the timing and stiffness of the controller based on participant performance. New software for the Lokomat [10] (B) adjusts the shape of the desired stepping trajectory based on participant interaction forces, as well as the robot impedance. HWARD [157] (C), the hand robot, uses triggered assistance, which means that it allows free movement for a fixed time for each desired task, and then responds by moving the hand if the participant does not achieve the task. T-WREX [88] (D) uses passive gravity balancing to provide assistance, with the number of elastic bands determining the amount of assistance. Pneu-WREX [50] (F) builds a real-time computer model of the participant's weakness, and uses it to provide feedforward assistance with a compliant position controller.