Figure 1. Schematic illustration of the pendulum-type friction tester and a sample of damping curve recorded by the three-dimensional dynamic angle-sensor. The total compressive load was 50 N or 80 N, and the initial swing was approximately 5°, which was commenced immediately after the load was set. By the three-dimensional dynamic angle-sensor, three angular velocities and three angles are measured round three axes, i.e., a roll, a pitch, and a yaw axis. From the total six measurements obtained, the three-dimensional movements of the condyle along the articular surface were calculated.