“…Thus, since incremental encoders can only generate a pulse train with its frequency related to the shaft velocity, a suitable estimation algorithm should be applied in order to obtain smooth velocity information. Although there has been extensive past research related to this issue over the past few decades [26,27], new emerging applications in robotics and other areas with cutting-edge requirements foster further intensive research in this field, e.g., the motion control of hydraulic actuators [28], pneumatic actuators [29], haptic interfaces [30], mobile robots [31], robot manipulators [32], humanoid robots [33], and collaborative robots for safe physical human-robot interaction [34], automotive applications [35], etc. Since the performance of a velocity control loop is related strongly to the quality of the velocity feedback information, achieving a smooth, high-bandwidth velocity estimate, which is required for oscillation-free high-bandwidth control loops, still presents quite a challenge.…”