Exploring on Performance of a Lower Limb Attached Artificial Bi-articular Muscle on the Body Part Where No Innate Muscle Exists

Recently, a great deal of attention has been paid to wearable robots supporting human performance in the engineering field. Most existing wearable robots are enabled to support human power by attached actuators on each joint. On the other hand, previous research demonstrated that the coordinated control of monoarticular muscle and biarticular muscle would provide functions of adjusting the force direction and keeping the posture. Meanwhile a little research focused on the coordinated control to support human performance. When comparing humans and ungulates lower limb skeletal muscle, ungulates possess the biarticular muscle where is not in human body and the coordinated control provides predominant mobility capability, therefore this research explored the performance of a lower limb attached artificial muscle on the front of shin where no innate biarticular muscle exists. The experiment device was designed to determine the force and displacement of a toe with the artificial muscle. Based on the preliminary survey result, the applied tension of the artificial muscle and angle of each joint were set as the experimental conditions. The result of the experiments showed that applying tension of the artificial muscle caused the expansion of the toe force output area and the high toe stiffness under the specific conditions. Furthermore, it was found out that the part of muscle activity decreased. From the results, the method changing the angle for adjusting toe force and keeping the posture was suggested. This method is expected to be used for the ability of supporting posture maintenance at unstable places.