Improvement of knee flexion and extension simulation accuracy in KneeRobo

In a previous paper, we reported on the initial development of KneeRobo, which replicates knee joint troubles experienced by patients in order to enable students studying to become physical or occupational therapists to gain practical training/testing virtually. We also developed a control algorithm that enabled KneeRobo to realize involuntary internal/external rotation during knee flexion and extension. However, it is well known that in addition to internal/external rotation, abduction/adduction also occurs involuntarily during knee flexion and extension. Consequently, this paper proposes a new control method that improves the simulation accuracy of KneeRobo´s knee joint movements. This is accomplished by developing a control algorithm and designing a pulley arrangement that facilitates realization of involuntary movements such as internal/external rotation and abduction/adduction during knee flexion and extension by KneeRobo. The results of experimental comparison with the actual knee joint movements of a healthy person confirm that the knee joint movements simulated by the improved KneeRobo are accurate.