Novel Functional Task-Based Gait Assistance Control of Lower Extremity Assistive Device for Level Walking

A novel approach to functional task-based gait assistance control architecture and its preliminary evaluations are presented. This approach utilizes a finite state machine to implement a gait period detector to estimate the current gait period of the user among the six major periods. Furthermore, an impedance-based controller is used to produce the functional gait assistance at the hip and the knee joint in each detected gait period. This is the first experimental trial to offer gait assistance based on gait period functionality. The goal of this controller is to assist the gait of the impaired persons in order to reduce the walking efforts in their daily living. The performance of this approach is investigated on a single-leg lower extremity assistive device with a group of healthy subjects walking on a treadmill. Joint kinematics, assistive torques from assisted trial, and heart rates from all trials are recorded. Preliminary evaluation shows that this approach is capable of providing functional task gait assistance at hip and knee joint of the subject under varying walking speeds during level walking. In particular, at a constant speed of 1 km/h with five healthy subjects, when assisted with the device, it reduces their heart rate to statistically resemble the free-walking heart rates. Additionally, it decreases their physical efforts to substantially improve their performance, compared with their unassisted conditions.