A control method for transfemoral prosthetic knees in level walking and stair ascending based on thigh angular motion

Regaining the locomotive ability is necessary to maintain the activities of daily living in lower extremity amputees. Recently, the stability of the gait and multifunctionality of transfemoral prosthetic knees have drastically improved with the use of microprocessor-controlled knees, such as Genium ® (Otto Bock, GmbH). However, these knees, which also include products from other companies, are very expensive. Therefore, the purpose of the present study was to develop a control method for transfemoral prosthetic knees in order to perform level walking and stairs ascending safely, with fewer sensors or simpler procedures. First, we analyzed the gait of an intact subject and therefore we proposed a control algorithm for prosthetic knees with only thigh angular kinematics. Then, an evaluation experiment on the prototype knee, in which the proposed algorithm was implemented, was conducted. As a result, the participant successfully performed level walking, stairs ascending and transition between the two types of gait. The functions of the prosthetic knee changed automatically using the proposed algorithm with thigh angular kinematics. Then, the reliability of the algorithm was checked with a database of gait analyses. The results showed that the algorithm was applicable to 99.8 % of the population.