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Assistive torque control is important for people who cannot fully accomplish sit-to-stand and stand-to-sit (STS) transitions. In this paper, we proposed a three-level control strategy for a bionic knee exoskeleton based on real-time STS transition recognition. Motion features were obtained from one potentiometer and two inertial measurement units integrated in the exoskeleton. A multi-class support vector classifier was utilized to infer the subject's real-time motion intent. Twelve able-bodied subjects were recruited in experiments. Mean accuracy across subjects was 97.63% ± 0.01%. Once STS transition was detected, the proposed control system could add assistive torque in time to assist the subject to accomplish the transition. • We proposed a three-level control strategy for a bionic knee exoskeleton based on real-time STS transition recognition. • A multi-class support vector classifier was utilized to infer the subject's real-time motion intent. • Mean accuracy across subjects was 97.63% ± 0.01%. [ABSTRACT FROM AUTHOR]

The range of motion (ROM) measurement is an important issue in a robot-assisted ankle–foot rehabilitation. This study presents a therapist-joined method to improve the ROM measurement accuracy of a robotic ankle–foot rehabilitation system by combining therapist-joined zero-torque control and proxy-based sliding mode control. The zero-torque control is applied when measuring the subject’s range of motion to obtain its extreme joint angle and largest resistance torque. Moreover, a controller switch is applied to ensure that the extreme joint angle is appropriate. Comparative studies between the ROM measurement using a protractor and the proposed method are then performed, comparing the ankle resistance torque variations during stretching under different ROM-measuring results. Ten able-bodied subjects are recruited for this experiment. The results show that the proposed method is feasible in improving the measured ROM accuracy. In addition, a more accurate ROM leads to a larger improvement of the ankle stiffness. [ABSTRACT FROM AUTHOR]

Ankle joint with spasticity and/or contracture can severely disable the mobility and the independence of stroke survivors. In this paper, we developed a proprioceptive neuromuscular facilitation (PNF) integrated robotic ankle–foot system for post stroke rehabilitation. The system consists of a robotic platform and a control system with graphic user interface. We employ five normal subjects to test the reliability and feasibility of the proposed system. To validate the effectiveness of the PNF integrated robotic system, we recruit five stroke patients and carry out a six-week PNF treatment. Treatment outcome was evaluated quantitatively in passive and active joint properties. The passive hysteresis loop shows that the maximum dorsiflexion angle increases from 32.9 ° ± 1.5 ° to 42.0 ° ± 3.2 ° ( p = 0.014 ) while the resistance torque decreases from 45.6 Nm±5.8 N m to 29.8 N m±4.4 N m ( p = 0.019 ). The active joint properties are improved significantly with the training score increasing from 5.7 ± 0.9 to 8.1 ± 0.6 , and getting close to that of normal subjects ( 9.5 ± 0.3 ). In addition, muscle strength has a rising trend as time goes on. The results demonstrate that the proposed PNF integrated robotic ankle–foot rehabilitation system is effective in improving ankle spasticity and/or contracture and is a promising solution in clinical rehabilitation. [ABSTRACT FROM AUTHOR]