Automatic actuator control by leg load signal of active AFO for Achilles tendon ruptures

This paper describes automatic actuator control hardware for an active ankle foot orthosis (AAFO) for a ruptured Achilles tendon. The sole of the AAFO is equipped with a servomotor. The actuator can switch the upright and the forward stepping posture of the patient. To control the actuator automatically during a gate cycle, 1: joint kinematics were analyzed that consisted of both stick pictures and EMG signals from the affected limb when the patient was walking on a treadmill. The cross-correlation coefficient between the ankle angle and the EMG signal of the lower limb (tibialis anterior) was small when the patient was wearing the AAFO. 2: An air pressure sensor and a film sensor were compared experimentally to measure the leg load. A prototype AAFO with automatic control was realized by using the leg load signal provided by an air pressure sensor to realize actuator control.