Planar motor rotor displacement measuring device and its measuring method

• US 9,766,054 B2
• Filed: 02/08/2013
• Issued: 09/19/2017
• Est. Priority Date: 02/17/2012
• Status: Active Grant

• Current Assignee: Shanghai Micro Electronics Equipment Company Limited, Tsinghua University
• Original Assignee: Shanghai Micro Electronics Equipment Company Limited, Tsinghua University
• Inventors: Hu, Jinchun, Zhu, Yu, Yin, Wensheng, Chen, Longmin, Yang, Kaiming, Zhang, Ming, Xu, Dengfeng, Mu, Haihua, Hu, Chuxiong, Liu, Zhao
• Primary Examiner(s): Le, John H
• Application Number:
  US14/379,106
• Publication Number:
  US 20150012242A1
• Time in Patent Office: 1,684 Days
• Field of Search: 702127, 702150, 702151, 310 1205, 310 1206, 310 1225, 318135, 318652, 318560, 3242072, 32420711, 32420712, 32420715, 32420724, 32420725
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01D 5/2013 by a movable ferromagnetic element, e.g. a core G01D5/2033 takes precedence
• CPC Class Codes: G03F 7/70758 Drive means, e.g. actuators, motors for long- or short-stroke modules or fine or coarse driving

Abstract

A planar motor rotor displacement measuring device and its measuring method are provided. The motor is a moving-coil type planar motor. The device comprises probes, two sets of sine sensors, two sets of cosine sensors, a signal lead wire and a signal processing circuit. The method is arranging two sets of magnetic flux density sensors within a magnetic field pitch τ along two vertical movement directions in the rotor located in the sine magnetic field area. Sampled signals of the four sets of sensors are respectively processed with a frequency multiplication operation, four subdivision signals are obtained, the zero-crossing points of the four subdivision signals are detected, and then two sets of orthogonal pulse signals are generated. The pulse number of the orthogonal pulse signals is counted, and phase difference of the two sets of orthogonal pulse signals is respectively detected.

Claims

1. A planar motor rotor displacement measuring device, wherein the planar motor is a moving-coil type planar motor comprising a stator (1) and a rotor (3) on the stator (1), the stator (1) includes a magnetic steel array (2), and a coil array (4) is arranged on the lower surface of the rotor (3), characterized in that:

the displacement measuring device comprises a probe (5), two sets of sine sensors, two sets of cosine sensors, a signal lead wire (6) and a signal processing circuit (7);

the probe (5) is arranged at the edge of the rotor (3) which is located in a sine magnetic field area generated by the magnetic steel array of the stator of the moving-coil type planar motor;

the two sets of sine sensors include an x-direction sine sensor set (8) and a y-direction sine sensor set (10), the two sets of cosine sensors include an x-direction cosine sensor set (9) and a y-direction cosine sensor set (11);

a plurality of sensors are arranged in the probe (5) including a reference sensor (12), wherein m_y sensors in total including the reference sensor (12) are uniformly arranged within one magnetic field pitch τ

along an x-direction, forming the y-direction sine sensor set and m_x sensors in total including the reference sensor (12) are uniformly arranged within one magnetic field pitch τ

along a y-direction, forming the x-direction sine sensor set;

wherein, beginning at a distance of τ

/4 from the reference sensor (12) in the y-direction, m_y sensors are uniformly arranged within one magnetic field pitch τ

along the x-direction, forming the y-direction cosine sensor set;

wherein, beginning at the distance of τ

/4 from the reference sensor (12) in the x-direction, m_x sensors are uniformly arranged within one magnetic field pitch τ

along the y-direction, forming the x-direction cosine sensor set, where m_x=2, 3, 4, . . . , m_y=2, 3, 4, . . . ;

wherein the signal processing circuit (7) is connected with an output of the probe (5) via the signal lead wire (6);

wherein the signal processing circuit (7) includes an analog signal processing unit and a digital signal processing unit; and

wherein the magnetic field pitch τ

is a spatial period of the sine magnetic field of the planar motor.

2. A planar motor rotor displacement measuring method using the device of claim 1, characterized in that, the method includes:

1) processing, by the analog signal processing unit of the signal processing circuit, sampled signals of the x-direction sine sensor set, sampled signals of the x-direction cosine sensor set, sampled signals of the y-direction sine sensor set and sampled signals of the y-direction cosine sensor set, so as to obtain an x-direction sine measurement signal S_X0, an x-direction cosine measurement signal C_X0, a y-direction sine measurement signal S_Y0 and a y-direction cosine measurement signal C_Y0, respectively;

2) processing the x-direction sine measurement signal S_X0 and the x-direction cosine measurement signal C_X0 with the following n_X frequency multiplication operations by the digital signal processing unit of the signal processing circuit, so as to obtain an x-direction sine subdivision signal S_XnX and an x-direction cosine subdivision signal C_XnX;

3. The planar motor rotor displacement measuring method of claim 2, characterized in that, n_X described at step 2) is determined as follows:

given that the B_XM is the magnitude of the magnetic induction intensity in the x-direction of the sine magnetic field generated by the magnetic steel array of the stator of the planar motor, and v_x is the noise in the sensor measurement in the x-direction, then the maximized number of times of the frequency multiplication operations in the x-direction is