Linear motor moving body position detection device based on linear hall sensor

Abstract

The application discloses a linear motor moving element position detection device based on linear Hall sensors, comprising a magnetic element and a plurality of speed measurement units; wherein the speed measurement unit comprises two linear Hall sensors and a first signal processing circuit, the two linear Hall sensors convert the magnetic signals sensed when the moving element passes through into two-way orthogonal single-end position signals, and the first signal processing circuit converts the two-way orthogonal single-end position signals into two groups of differential position signals. The non-contact position detection device based on the linear Hall sensors and the magnetic element of the application, and the single-end position signals of the linear Hall sensors are converted into differential position signals for transmission, which is beneficial to improving the accuracy, reliability and anti-interference ability of the position signal measurement applied to the working condition of the long-stroke high-speed linear motor.

Description

Technical Field

[0001] This disclosure relates to the field of linear motor speed measurement technology, and more specifically, to a long-stroke high-speed linear motor mover position detection device based on magnetic sensing. Background Technology

[0002] A linear motor is a transmission device that directly converts electrical energy into linear motion mechanical energy. Traditional rotary motors with a conversion mechanism are far from meeting the requirements of modern control systems. Linear motors, due to their simple structure, direct transmission, and fast response, have developed rapidly and are widely used in industrial fields such as elevators, high-speed maglev trains, and high-precision machine tools. The mover is the mechanism in a linear motor that performs reciprocating linear motion. The control system of a linear motor must employ closed-loop control with mover position feedback. Therefore, for high-speed linear motors, a highly reliable and high-resolution mover position detection system is required. Accurate mover position detection is a necessary condition for the precise control and operation of a linear motor.

[0003] Currently, the most commonly used position sensors are optical encoders (or magnetic encoders). These sensors offer high position resolution and length flexibility; for example, Heidenhain's absolute optical encoders can achieve a resolution of 10 nm and offer selectable lengths. With a well-designed controller, position control accuracy can reach the micrometer level. However, they suffer from drawbacks such as high cost and susceptibility to harsh environments. When there is significant dust in the environment or the system is subjected to external vibrations, the sensor performance degrades considerably, limiting their practical value in engineering applications.

[0004] Considering the characteristics of the movement of the mover in a high-speed linear motor, and taking into account factors such as non-contact design, sensitivity, reliability, and anti-interference capability, Hall effect sensors can be used to detect the mover position. Based on their different working principles, Hall effect sensors can be divided into switch-type Hall effect sensors and linear Hall effect sensors.

[0005] Switching Hall effect sensors output position signals in the form of only 0 and 1, simplifying engineering implementation. However, in practical applications, there are risks associated with the machining accuracy of structural components and signal delay errors. For long-stroke, multi-segment linear motors, multiple pairs of Hall effect sensors are typically required to measure the entire stroke of the mover. Because the edge alignment requirements of the switching signals output by each pair of Hall effect sensors are very high, this places high demands on their installation spacing. Furthermore, the distance between the switching Hall effect sensor and the surface being detected is critical, generally not exceeding 4mm. Errors in the machining, positioning accuracy, and sensor installation accuracy of the magnetic rack teeth can easily lead to problems such as non-parallelism between the sensor detection surface and the tooth surface, uneven detection distances among sensors in the sensor array, and a square wave signal duty cycle deviating from 50%. Additionally, there is a certain delay in the signal as it passes through various components in the system. These risks and errors in practical applications can all cause deviations or even errors in the detection of the mover position signal.

[0006] Linear Hall effect sensors have an output voltage that is directly proportional to the magnetic field strength within a linear range, offering advantages such as high accuracy, small size, light weight, and low cost. However, the analog signals output by linear Hall effect sensors are more difficult to process than switching signals and are susceptible to electromagnetic interference. Therefore, a device specifically designed for detecting the position of a long-stroke, high-speed linear motor's rotor needs to be developed to address the operational characteristics of linear Hall effect sensors. This device transmits and processes the position information measured by the sensor, enabling the control system to obtain accurate and reliable rotor position information.

[0007] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this disclosure is to provide a linear motor mover position detection device based on a linear Hall sensor, thereby overcoming, at least to some extent, one or more problems caused by the limitations and defects of related technologies.

[0009] This invention provides a linear motor mover position detection device based on a linear Hall sensor, comprising:

[0010] Magnetic components are arranged along the length of the linear motor's rotor.

[0011] Multiple speed measuring units are spaced apart along a first direction parallel to the travel direction of the linear motor mover, and the distance between adjacent speed measuring units is less than the length of the magnetic element.

[0012] The speed measuring unit includes two linear Hall sensors and a first signal processing circuit. The two linear Hall sensors convert the magnetic signal sensed when the mover passes into two orthogonal single-ended position signals. The first signal processing circuit converts the two orthogonal single-ended position signals into two sets of differential position signals.

[0013] Furthermore, it also includes a signal aggregation unit, which is located at a position away from the magnetic field formed by the magnetic element and connected to each speed measuring unit. The signal aggregation unit is used to convert the two sets of differential position signals output by the speed measuring unit into two single-ended analog signals through amplitude limiting and voltage division.

[0014] Furthermore, it also includes an analog-to-digital conversion unit, which is connected to the signal aggregation unit and the motor control system respectively, and is used to convert the two single-ended analog signals output by the signal aggregation unit into two single-ended digital signals representing the position of the mover and send them to the motor control system.

[0015] Furthermore, the two linear Hall sensors are spaced apart along the first direction, and the distance between the two linear Hall sensors is half the pole distance of the magnetic element.

[0016] Furthermore, the first signal processing circuit includes two first operational amplifier chips and two filter circuits. The signal input terminals of the two first operational amplifier chips are connected to the two linear Hall sensors respectively, receiving two orthogonal single-ended position signals from the two linear Hall sensors. The common-mode voltage control terminal of the first operational amplifier chip is connected to the ground terminal through a capacitor to adjust the common-mode voltage of the two sets of differential signals. The signal output terminal of the first operational amplifier chip is connected to the filter circuit. The signal output terminals of the two first operational amplifier chips output two sets of differential signals with a predetermined common-mode voltage. The two filter circuits convert the two sets of differential signals output by the two first operational amplifier chips into the two sets of differential position signals after performing a first-stage RC low-pass filter.

[0017] Furthermore, the filtering circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, and a second capacitor. The first end of the first resistor is connected to the first end of the second resistor and receives one signal from the differential signal. The second end of the first resistor is connected to the ground terminal and the first end of the first capacitor. The second end of the second resistor is connected to the second end of the first capacitor and outputs one signal from the differential position signal. The first end of the third resistor is connected to the first end of the fourth resistor and receives another signal from the differential signal. The second end of the third resistor is connected to the ground terminal and the first end of the second capacitor. The second end of the fourth resistor is connected to the second end of the second capacitor and outputs another signal from the differential position signal.

[0018] Furthermore, it also includes a power supply unit, which is located away from the magnetic field formed by the magnetic element and supplies power to the signal aggregation unit; the signal aggregation unit includes a power conversion module and a second signal processing circuit, the power conversion module converts one power supply voltage output by the power supply unit into two power supply voltages to supply power to the linear Hall sensor and the first signal processing circuit respectively.

[0019] Furthermore, the second signal processing circuit includes a second operational amplifier chip and two amplitude reduction and voltage divider circuits. The signal input terminal of the second operational amplifier chip is connected to the first signal processing circuit and receives two sets of differential position signals output by the first signal processing circuit. The signal output terminal of the second operational amplifier chip outputs two single-ended signals with an amplitude of 0-5V. The two amplitude reduction and voltage divider circuits convert the two single-ended signals output by the second operational amplifier chip into two single-ended signals with an amplitude of 0-3V after amplitude limiting and voltage division processing.

[0020] Furthermore, the distance between the two linear Hall sensors and the magnetic element in a second direction perpendicular to the first direction is 18-25 mm.

[0021] Furthermore, the magnetic element is a permanent magnet, which is fixed to the top of the linear motor mover, and the length of the permanent magnet corresponds to the length of the linear motor mover.

[0022] The present invention provides a non-contact position detection device based on a linear Hall sensor and a magnetic element. By converting the single-ended position signal of the linear Hall sensor into a differential position signal for transmission, it is beneficial to improve the accuracy, reliability and anti-interference capability of position signal measurement in the case of long-stroke high-speed linear motors.

[0023] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0024] The above and other features and advantages of this disclosure will become more apparent from the detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0025] Figure 1 and 2 A schematic diagram of the structure of a linear motor mover position detection device according to an exemplary embodiment of the present disclosure is shown;

[0026] Figure 3 A schematic diagram of the structure of a speed measuring unit board according to an exemplary embodiment of the present disclosure is shown;

[0027] Figure 4 A schematic diagram of a first signal processing circuit on a speed measuring unit board according to an exemplary embodiment of the present disclosure is shown;

[0028] Figure 5 A waveform diagram illustrating signal conversion performed by a speed measuring unit and a signal summarizing unit according to an exemplary embodiment of the present disclosure is shown.

[0029] Figure 6 A schematic diagram illustrating the communication connection between a signal aggregation unit and a speed measuring unit according to an exemplary embodiment of the present disclosure is shown.

[0030] Figure 7 A schematic diagram of a signal processing circuit on a signal summarization board according to an exemplary embodiment of the present disclosure;

[0031] Figure 8 A schematic diagram illustrating the power supply method of the power supply unit to the signal aggregation board and the speed measurement unit board according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0032] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0033] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of the specific details described, or other methods, components, materials, apparatuses, steps, etc., can be employed. In other instances, well-known structures, methods, apparatuses, implementations, materials, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0034] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, or in one or more software-hardened modules, or in different network and / or processor devices and / or microcontroller devices.

[0035] In this example embodiment, as Figure 1 and 2 As shown, the present invention provides a linear motor mover position detection device based on a linear Hall sensor, comprising:

[0036] Magnetic element 11 is arranged along the length of the linear motor mover 10. The magnetic element 11 can be a permanent magnet used to generate a magnetic field, the trend of which reflects the position of the mover. The magnetic field generated by the permanent magnet has a certain sinusoidal property. The permanent magnet is reliably fixed to the mover 10 by a mounting frame and moves with the mover 10; therefore, the position of the permanent magnet reflects the position of the mover.

[0037] Multiple speed measuring units 12 are spaced apart along a first direction parallel to the travel direction of the linear motor mover 10, with the spacing between adjacent speed measuring units being less than the length of the magnetic element 11, to achieve position detection covering the entire stroke of the linear motor. Each speed measuring unit 12 includes two linear Hall sensors and a first signal processing circuit. The two linear Hall sensors convert the magnetic signal sensed when the mover passes into two orthogonal single-ended position signals, and the first signal processing circuit converts these two orthogonal single-ended position signals into two sets of differential position signals. To achieve optimal magnetic field measurement performance, the spacing between the two linear Hall sensors and the magnetic element in a second direction perpendicular to the first direction is 18-25 mm.

[0038] In this embodiment, the speed measuring unit 12 is a speed measuring unit board. The speed measuring unit board is fixed to the linear motor guide rail 14 by a mounting bracket 13. The distance between the speed measuring unit board and the permanent magnet can be finely adjusted by the mounting bracket 13. Multiple speed measuring unit boards can be set on the same side of the linear motor guide rail by the mounting bracket 13, or they can be alternately set on both sides of the linear motor guide rail. Figure 3 As shown, the speed measuring unit board is equipped with two linear Hall sensors and a first signal processing circuit. The two linear Hall sensors are spaced apart along a first direction, and the distance between the two linear Hall sensors is half the pole pitch of the magnetic element. When the magnetic element 11 moves with the linear motor mover 10 to the position of the speed measuring unit 12, the two linear Hall sensors can convert the sensed magnetic signal into two orthogonal single-ended position signals. Since the two linear Hall sensors of the speed measuring unit 12 operate in a strong electromagnetic field environment generated by the magnetic element 11, in order to avoid interference from the strong electromagnetic field environment, the speed measuring unit board is equipped with a first signal processing circuit. The first signal processing circuit converts the two orthogonal single-ended position signals into two sets of differential position signals to reduce electromagnetic interference and improve the position accuracy of the mover sensed by the two linear Hall sensors.

[0039] The signal processing scheme of speed measuring unit 12 is as follows: Figure 4As shown, the single-ended signals output by the two Hall sensors P1 and P2 on the speed measurement unit board are HALL1 and HALL2, respectively. The first signal processing circuit includes two first operational amplifier chips U1 and U2 and two filter circuits. The two first operational amplifier chips U1 and U2 are AD8476ARMZ chips. The single-ended signal input terminals 1 and 8 of the first operational amplifier chips U1 and U2 are respectively connected to the single-ended signals HALL1 and HALL2 of the two Hall sensors P1 and P2. The first operational amplifier chips U1 and U2 are connected to a 15V power supply. The VCOM pin of the first operational amplifier chips U1 and U2 adjusts the common-mode voltage of the two sets of differential signals. The first operational amplifier chips U1 and U2 output two sets of differential signals DIFF1+, DIFF1- and DIFF2+, DIFF2-, respectively. Two filtering circuits convert the two sets of differential signals DIFF1+, DIFF1- and DIFF2+, DIFF2- output from the first operational amplifier chips U1 and U2 into two sets of differential position signals DIFF1OUT+, DIFF1OUT- and DIFF2OUT+, DIFF2OUT- after a single RC low-pass filter. By increasing the common-mode voltage and performing low-pass filtering, the anti-interference capability during position signal transmission can be further enhanced. The signal waveform conversion process is as follows: Figure 5 As shown, the amplitude of the analog voltage signals output by the two Hall sensors P1 and P2 is usually below 5V. They are prone to attenuation during long-distance signal transmission and are easily affected by strong electromagnetic fields.

[0040] The filtering circuit includes first resistors R14 and R16, second resistors R10 and R12, third resistors R15 and R17, fourth resistors R11 and R13, first capacitors C13 and C15, and second capacitors C14 and C16. The first terminals of the first resistors R14 and R16 are connected to the first terminals of the second resistors R10 and R12 and are connected to one of the differential signals, DIFF1+ and DIFF2+. The second terminals of the first resistors R14 and R16 are connected to the ground terminal and the first terminals of the first capacitors C13 and C15, respectively. The second terminals of the second resistors R10 and R12 are connected to the second terminals of the first capacitors C13 and C15. One signal, DIFF1OUT+, DIFF2OUT+, is output from the differential position signal. The first terminals of the third resistors R15 and R17 are connected to the first terminals of the fourth resistors R11 and R13, and are connected to the other signal, DIFF1-, DIFF2-, from the differential signal. The second terminals of the third resistors R15 and R17 are connected to the ground terminal and the first terminals of the second capacitors C14 and C16, respectively. The second terminals of the fourth resistors R11 and R13 are connected to the second terminals of the second capacitors C14 and C16, and are output to the other signal, DIFF1OUT-, DIFF2OUT-, from the differential position signal. The common-mode voltage of the two sets of differential signals is raised to 10V by the VCOM pin of the first operational amplifier chips U1 and U2. After passing through a first-stage RC low-pass filter, the signal attenuation during long-distance transmission and interference from strong electromagnetic fields can be further reduced.

[0041] like Figure 6 As shown, the linear motor mover position detection device also includes a signal aggregation unit 15, which can centrally process the mover position information sensed by multiple speed measuring units. When the linear motor stroke is long and the number of speed measuring units is large, the signal aggregation unit 15 can be used to send the signals sensed by multiple speed measuring units to one signal aggregation unit 15 for centralized signal processing. The number of aggregation units 15 can be adjusted according to the number of speed measuring units. In this embodiment, the aggregation unit 15 can be a signal aggregation board, which is located away from the magnetic field formed by the magnetic element and connected to the speed measuring unit via CAN or 485 communication. The signal aggregation board is used to convert the two sets of differential position signals output by the speed measuring unit into two single-ended analog signals through amplitude limiting and voltage division. Figure 7As shown, the signal aggregation board includes a second operational amplifier chip U201 and two amplitude divider circuits. The signal aggregation board needs to process multiple input high common-mode differential signals. In this embodiment, the second operational amplifier chip is the ADA4665-2ARZ dual-channel operational amplifier chip to build a differential-to-single-ended circuit. Pins 4 and 8 of the second operational amplifier chip U201 are connected to a 15V power supply. The two sets of input differential signals 1DIFFA+, 1DIFFA- and 1DIFFB+, 1DIFFB- are connected to pins 3 and 2 and pins 5 and 6 of the chip, respectively. Two single-ended signals 1HA and 1HB with amplitudes of 0-5V are output through pins 1 and 7. After being further conditioned by the amplitude divider circuit, they are converted into signals ADin0 and ADin1 with output amplitudes in the range of 0-3V. Finally, the analog signals are converted into digital signals by the analog-to-digital converter (ADC), thereby realizing the acquisition of the linear motor mover position information and sending it to the motor control system for precise control of the linear motor mover movement.

[0042] like Figure 8 As shown, since the speed measuring unit board is located in a strong magnetic field environment, no power supply module is installed on the speed measuring unit board for power supply safety considerations. The power supply unit is located away from the magnetic field formed by the magnetic components and supplies power to the signal aggregation unit. The signal aggregation unit includes a power conversion module, which converts one 15V supply voltage output from the power supply unit into one 15VDC and one 5VDC, which supply power to the linear Hall sensor and the first signal processing circuit respectively through a cable network. The entire device only requires one external power supply. This relatively centralized power supply method is simple and easy to implement, minimizes the number of power conversion modules, and simplifies the cable network of the device, which is beneficial for the modular expansion of the device.

[0043] In summary, the non-contact position detection device based on linear Hall effect of this invention is beneficial for improving the accuracy, reliability, and anti-interference capability of position signal measurement in long-stroke high-speed linear motor applications. The designed linear motor mover position detection device can be applied to scenarios where the mover permanent magnet cannot be directly measured. The pole pitch, arrangement, and shape of the velocimetric permanent magnet can be changed according to actual application needs, exhibiting strong flexibility and facilitating practical engineering applications. The designed signal transmission and processing circuit structure adopts an isolated amplification processing and transmission method for the position signal measured by the sensor, which helps to enhance the reliability and anti-interference capability of signal detection.

[0044] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0045] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A linear motor mover position detection device based on a linear Hall sensor, characterized in that, include: Magnetic components are arranged along the length of the linear motor's rotor. Multiple speed measuring units are spaced apart along a first direction parallel to the travel direction of the linear motor mover, and the distance between adjacent speed measuring units is less than the length of the magnetic element. The speed measurement unit includes two linear Hall sensors and a first signal processing circuit. The two linear Hall sensors convert the magnetic signal sensed when the mover passes into two orthogonal single-ended position signals. The first signal processing circuit converts the two orthogonal single-ended position signals into two sets of differential position signals. The first signal processing circuit includes two first operational amplifier chips and two filter circuits. The signal input terminals of the two first operational amplifier chips are connected to the two linear Hall sensors to receive the two orthogonal single-ended position signals. The common-mode voltage control terminal of the first operational amplifier chip is connected to the ground terminal through a capacitor to adjust the common-mode voltage of the two sets of differential signals. The signal output terminal of the first operational amplifier chip is connected to the filter circuits, and the signal output terminals of the two first operational amplifier chips output two sets of differential signals with a predetermined common-mode voltage. The two filter circuits perform a first-stage RC low-pass filter on the two sets of differential signals output by the two first operational amplifier chips and then convert them into the two sets of differential position signals.

2. The position detection device as described in claim 1, characterized in that, It also includes a signal aggregation unit, which is located at a position away from the magnetic field formed by the magnetic element and connected to each speed measuring unit. The signal aggregation unit is used to convert the two sets of differential position signals output by the speed measuring unit into two single-ended analog signals through amplitude limiting and voltage division.

3. The position detection device as described in claim 2, characterized in that, It also includes an analog-to-digital conversion unit, which is connected to the signal aggregation unit and the motor control system respectively, and is used to convert the two single-ended analog signals output by the signal aggregation unit into two single-ended digital signals representing the position of the mover and send them to the motor control system.

4. The position detection device as described in claim 1, characterized in that, The two linear Hall sensors are spaced apart along the first direction, and the distance between the two linear Hall sensors is half the pole distance of the magnetic element.

5. The position detection device as described in claim 1, characterized in that, The filtering circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, and a second capacitor. The first end of the first resistor is connected to the first end of the second resistor and receives one signal from the differential signal. The second end of the first resistor is connected to the ground terminal and the first end of the first capacitor. The second end of the second resistor is connected to the second end of the first capacitor and outputs one signal from the differential position signal. The first end of the third resistor is connected to the first end of the fourth resistor and receives another signal from the differential signal. The second end of the third resistor is connected to the ground terminal and the first end of the second capacitor. The second end of the fourth resistor is connected to the second end of the second capacitor and outputs another signal from the differential position signal.

6. The position detection device as described in claim 2, characterized in that, It also includes a power supply unit, which is located away from the magnetic field formed by the magnetic element and supplies power to the signal aggregation unit; the signal aggregation unit includes a power conversion module and a second signal processing circuit, the power conversion module converts one power supply voltage output by the power supply unit into two power supply voltages to supply power to the linear Hall sensor and the first signal processing circuit respectively.

7. The position detection device as described in claim 6, characterized in that, The second signal processing circuit includes a second operational amplifier chip and two amplitude reduction and voltage divider circuits. The signal input terminal of the second operational amplifier chip is connected to the first signal processing circuit and receives two sets of differential position signals output by the first signal processing circuit. The signal output terminal of the second operational amplifier chip outputs two single-ended signals with an amplitude of 0-5V. The two amplitude reduction and voltage divider circuits convert the two single-ended signals output by the second operational amplifier chip into two single-ended signals with an amplitude of 0-3V after amplitude limiting and voltage division processing.

8. The position detection device as described in claim 4, characterized in that, The distance between the two linear Hall sensors and the magnetic element in a second direction perpendicular to the first direction is 18-25 mm.

9. The position detection device as described in claim 1, characterized in that, The magnetic element is a permanent magnet, which is fixed to the top of the linear motor mover, and the length of the permanent magnet corresponds to the length of the linear motor mover.

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