Fig. 2

Schematic of the proposed AFO control The block diagram represents the ankle-foot orthosis (AFO) control strategy based on the gait-phase detection and valve control. We simplified the gait event with four different configurations: heel strike, foot flat, heel off, and toe-off in series (skin-colored leg). The process from the start of the heel strike to the end of the heel off is called the stance phase of the gait cycle. After toe off, the foot is off the ground, and the swing phase starts until the next heel strike event. To provide a control input of the patient’s gait phase to the AFO, we first designate the boundary value of each GRF sensor (\({s}_{1.max}\): heel boundary value, and \({s}_{2.max}\): toe boundary value). The boundary value is determined as the sensor value (\({s}_{1}\): heel value, and \({s}_{2}\): toe value) when each part of the insole (heel and toe) of each person touches the ground. This leads to the dorsiflexion assistance during the entire gait period except when the foot is flat