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LINEAR MOTOR WITH COGGING COMPENSATION FIELD [0001] The present description relates to methods and apparatus for high resolution control of 5 linear motors, and more particularly to the use and control of such motors in electromechanical systems for lithography. BACKGROUND [0002] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually 10 onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g., including part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto 15 a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”- 20 direction) while synchronously scanning the substrate parallel or anti parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate. BRIEF DESCRIPTION OF THE DRAWINGS 25 [0003] Embodiments will now be described, by way of example only, with reference to the accompanying drawings in which: [0004] Figure 1 schematically depicts an embodiment of a lithographic apparatus; [0005] Figure 2 schematically depicts an embodiment of a lithographic cell or cluster; [0006] Figure 3 schematically illustrates a linear motor; 30 [0007] Figure 4 schematically illustrates a control system for a linear motor incorporating force sensors in accordance with an embodiment; [0008] Figure 5 schematically illustrates an arrangement of force sensors; [0009] Figure 6 schematically illustrates an alternate force sensor arrangement; [0010] Figure 7 schematically illustrates an arrangement of acceleration sensors; 35 [0011] Figure 8 schematically illustrates an alternate arrangement of acceleration sensors; [0012] Figure 9 schematically illustrates an additional alternate arrangement of acceleration 1 sensors; and [0013] Figure 10 schematically illustrates an additional alternate arrangement of acceleration sensors. 5 DETAILED DESCRIPTION [0014] Before describing embodiments in detail, it is instructive to present an example environment in which embodiments may be implemented. [0015] Figure 1 schematically depicts a lithographic apparatus LA. The apparatus comprises: - an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. 10 DUV radiation or EUV radiation); - a support structure (e.g. a mask table) MT constructed to support a patterning device (e.g. a mask) MA and connected to a first positioner PM configured to accurately position the patterning device in accordance with certain parameters; - a substrate table (e.g. a wafer table) WTa constructed to hold a substrate (e.g. a resist-coated 15 wafer) W and connected to a second positioner PW configured to accurately position the substrate in accordance with certain parameters; and - a projection system (e.g. a refractive projection ...