截瘫助行外骨骼髋关节离合式弹性驱动器

Lower limb exoskeletons can help paraplegic patients walk through rehabilitation. Powered exoskeletons do not require much muscle strength in the affected limbs, but the drive motors are rather large and heavy. Unpowered energy-storage exoskeletons do not require motors, but require more patient muscle strength which may cause fatigue during continuous use. This paper describes a clutched elastic actuator based on a ratchet mechanism that can be used as the hip joint driver for a lower limb of an exoskeleton. Patients rely on their upper limb and trunk muscles and crutches to slowly transfer the center of gravity during the support phase. The motor then stores energy during this motion in a torsional spring. During the swing phase, the torsional spring then quickly releases energy to help the patient step forward and complete a gait cycle. This paper presents a model for the driver during the support phase (spring energy storage) and the swing phase (spring energy release). The angular acceleration and deceleration are selected to minimize the peak power. Simulations show that the clutched elastic actuator significantly reduces the average power and the peak power compared with a motor and gearbox driving the patient's hip joint. Therefore, the system can have small low torque, low power motors to reduce the size and weight of the actuators and the entire exoskeleton.