| 摘要 |
<p>A lithographic apparatus comprises moveable objects. A position of these moveable objects may be controlled by a position control system. A position control system according to the present invention comprises a position controller (6), an object represented as an object filter (Ho), a position feedback circuit (22), and an acceleration control system (34). The acceleration control system 34 comprises a subtractor (8) and a first filter (Hf) in a first circuit branch and a second filter (Hs) in a second circuit branch. A position controller signal (Fp) output from the position controller (6) is input into the subtractor (8) of the acceleration control system (34). An external disturbance force (Fd), however, is directly exerted upon the object (Ho). Thus, a first transfer function (G1) from the input of subtractor (8) to the acceleration of the object (Ho) for the position controller force (Fp) may be different than a second transfer function (G2) from the input of object (Ho) to the acceleration of the object (Ho) for the disturbance force (Fd). Preferably, the first transfer function (G1) is identical to a transfer function for the position controller force (Fp) in case no acceleration control system (34) is present in the position control system.</p> |
