| 摘要 |
Black/ white keys (70) are selectively moved by key actuators (104) energized with a driving signal in a playback mode, and plunger sensors (10), which are provided inside of the key actuators (104), report the measured values (xj) of the keystroke to a motion controlling section (120); since the measured values (xj) contain noise due to the deformation of the keys (70), the motion controlling section (120) estimates true values or estimated values (V; X) of the keystroke by dividing the sum of products between the measured values (xj) and weighting factors (wVj; wXj) by a normalizing constant (WV; WX), and compares the estimated values (WV; WX) with target values to see whether or not the keys (70) exactly travel on reference trajectories; if the answer is negative, the motion controlling section (120) varies the duty ratio of the driving signal so as to accelerate or decelerate the keys (70). |
