Muscle Force Prediction Method Considering the Role of Antagonistic Muscle

Conventional musculoskeletal model often uses the optimization method to estimate muscle forces. However, the optimization method unfortunately does not usually consider the role of antagonistic muscles, which act in opposite direction to the prime motion or for restriction of rotational joint motion. Therefore, this study proposes a new method to estimate muscle forces considering the role of the antagonistic muscle during 3-dimensional motion. In this model, it is assumed that the agonist muscle is connected to the antagonistic muscle by a coupled spring. Joint torque is defined as the summation of the torques derived from the agonist muscles and the torques derived from the antagonistic muscles. Each muscle force can be estimated to keep balance among the torques generated by the agonist muscles and the antagonistic muscles respectively. The experiments were conducted to validate the proposed method to estimate muscle forces. Surface electromyograms (sEMG) were measured to compare with the estimated muscle forces. The experimental results showed that the estimated muscle forces had a good agreement with the sEMG of muscles.