| 摘要 |
A seismic shaker (1) for exercising an excitation force on the ground (4) has a base plate (3) and a reaction mass (5) connected to the base plate via a resilient structure (7) and an actuator (9) parallel thereto. A first comparison unit (19) sends a difference signal (21) which is the difference between a displacement (27) measured by a displacement sensor (17) and a set value (25) of the displacement. A control unit (29) calculates a correction value (31) as a function of this difference signal, and sends it to a second comparison unit (33), which adds the correction value to a value of the excitation force to be exerted set in the second comparison unit (33). This second comparison unit is connected to a controller unit (15) which controls the actuator. At Low frequency this position control will track the ground force through the position set-point. The position feedback loop will be able to suppress the interfering force of the spring and any hysteresis. |
