Linear encoder has been widely used in various position controls in industries, especially in machinery industry. The purpose of using linear encoders is to give precise position control in dynamic applications. Furthermore, using linear encoders helps minimize errors caused by human or mechanical problems such as backlash and thermal expansion [2]. There are various types of linear encoders such as mechanical, optical, magnetic, etc. Nevertheless, magnetic encoders are able to withstand harsh environment such as oil, grease, and dust much effective than the rest. Magnetic encoders have several advantageous qualities: low cost, fast response, and high reliability [1, 3]. Figure 1 shows the magnetic field of a magnetic scale where the yellow curves indicate the change of magnetic poles. The upper half of the scale is the incremental mark and the bottom half is the reference mark. Prior to magnetization, the scale has only the incremental mark, and the magnetizing process is to magnetize bottom half of the incremental mark into reference mark as shown in Fig. 1.
A Nonlinear Magnetic Stabilization Control Design for an Externally Manipulated DC Motor: An Academic Low-Cost Experimental Platform