A Soft Robotic Hip Exosuit (SR-HExo) to Assist Hip Flexion and Extension during Human Locomotion

This paper presents the design, fabrication, and preliminary results of a soft hip exosuit to assist hip flexion and extension during walking. The exosuit uses soft and compliant materials to create a wearable robot that has a low profile, low mass, and is highly flexible to freely move with the user's natural range of motion. The Soft Robotic Hip Exosuit (SR-HExo) consists of flat fabric pneumatic artificial muscles (ff-PAM) that contract when pressurized. The ff-PAM actuators are oriented in an 'X' shape to allow for natural range of motion across the hip joint and can generate 190 N of force at 200 kPa in a 0.3 sec window. The 'X' configuration (X-ff-PAM) actuators were placed on the anterior and posterior sides of the hip joint with height adjustable Velcro straps. Extension assistance and flexion assistance was provided in 10-45% and 50-90% of the gait cycle, respectively. To evaluate the effectiveness of the SR-HExo with healthy participants, hip range of motion and muscle activity during walking were monitored using a motion capture system and surface electromyography sensors. The impact of the SR-HExo on the range of motion was minimal with only a 4.0 reduction from the target range of motion of 30. The exosuit contributed to reducing hip muscle activity. Hip extensor muscles showed a reduction of 13.1% for the gluteus maximus and 6.6% for the biceps femoris. Hip flexor muscles showed a reduction of 10.7% for the iliacus and 27.7% for the rectus femoris.