A gravity unloading controller for a lorentz force magnetic levitation gimbal stabilized platform

Abstract

The application relates to a gravity unloading controller of a Lorentz force magnetic suspension universal stable platform. Main components include a host computer PC, a lower computer FPGA, a program-controlled direct current power supply, an optical encoder, a linear displacement sensor, an AD conversion module and the Lorentz force magnetic suspension universal stable platform. When the attitude movement of the platform load cabin causes the gravity center to change, the optical encoder measures the angular displacement information and sends the angular displacement information to the lower computer FPGA, the lower computer FPGA packs the data signal and sends the data signal to the host computer PC, the host computer PC calculates the current size required for balancing and unloading the gravity, then sends the instruction to the program-controlled direct current power supply, and the program-controlled direct current power supply adjusts the current size of the magnetic bearing coil, so that the gravity unloading under the arbitrary attitude of the platform load cabin is realized. The application belongs to the field of spaceflight and can simulate the weightlessness environment in space on the ground, and support the research and demonstration verification of the attitude control technology of the Lorentz force magnetic suspension satellite and other floating space vehicles.

Description

Technical Field

[0001] This invention relates to a gravity unloading controller for a Lorentz force magnetic levitation omnidirectional stabilization platform, which is particularly suitable for simulating weightlessness environments in the aerospace field. Technical Background

[0002] While modern gravity unloading systems have achieved effective unloading of gravitational pressure to a certain extent, they still have some shortcomings, mainly in the following aspects:

[0003] Existing gravity unloading systems, such as the rotary joint ground gravity Lorentz force magnetic levitation unloading system described in authorized patent 202110728166.5, only meet the requirements of unidirectional gravity unloading. This may not provide sufficient solutions in a wider range of environments, such as spacecraft, where omnidirectional gravity unloading is required to simulate microgravity or zero-gravity environments, which cannot be well achieved. The design or control strategies of existing gravity unloading systems are not optimized enough, leading to energy loss or slow unloading speeds during the unloading process, thus affecting unloading efficiency. There are also issues with insufficient unloading accuracy, due to limitations in the system's sensors, controllers, or actuators. Gravity unloading systems need high stability to ensure performance maintenance during long-term use. However, some existing gravity unloading systems suffer from stability problems, such as performance degradation or failure due to mechanical wear, electrical faults, or environmental factors. Summary of the Invention

[0004] To address the above shortcomings, this application provides a Lorentz force magnetic levitation omnidirectional stabilization platform gravity unloading controller, which can achieve all-around gravity unloading and improve its unloading efficiency and accuracy, thereby better controlling the stability of the platform.

[0005] To achieve the above objectives, the controller comprises: a host PC, a slave FPGA, a programmable DC power supply, a photoelectric encoder, a linear displacement sensor, an AD conversion module, and a Lorentz force magnetic levitation omnidirectional stabilization platform.

[0006] The lower-level FPGA is connected to the photoelectric encoder disk, used to send a request for position information (MA) clock signal to the encoder disk and receive a request for position (SLO) data signal. The lower-level FPGA and the photoelectric encoder disk communicate via the BISS protocol, which has a high response speed and communication rate. The photoelectric encoder disk is connected to the main control board via a DB9 interface. The MA signal sent by the lower-level FPGA is converted from TTL level to a differential signal and output to the photoelectric encoder disk. Then, the SLO signal returned by the photoelectric encoder disk is processed by the chip and converted from a differential signal to TTL level before being input to the FPGA. (MA is a signal sent by the master device to activate or initialize data transmission with the sensor or other slave devices. SLO is a data signal sent by the slave device to transmit the data collected by the sensor back to the master device.)

[0007] The host PC and the slave FPGA are connected via Ethernet for signal exchange. The host PC sends sensor data read / write commands to the slave FPGA through an interface. The slave FPGA receives the commands and returns the corresponding data to the host PC. The host PC calculates the current required to unload the gravity using a custom formula.

[0008] The programmable power supply is connected to the host PC via a DB9 serial cable. Based on the selected communication protocol and instruction format, a control instruction for setting the power supply output current is constructed, and the host computer software sends the control instruction to the programmable power supply.

[0009] The lower-level FPGA is connected to the linear displacement sensor via an AD conversion module to receive the displacement signal output by the linear displacement sensor. A signal conditioning circuit is designed to condition the signal output by the linear displacement sensor, including amplification and filtering, to adapt to the input range and requirements of the AD conversion module. The AD conversion module converts the conditioned analog signal into a digital signal and outputs the digital signal, which is then transmitted to the lower-level FPGA via the SPI interface.

[0010] Although this example uses an optical encoder as an angular displacement sensor in the components of the controller, the controller design is universal, and other types of angular displacement sensors can also be used in this controller, requiring only corresponding adaptation and adjustment.

[0011] The present invention has the following advantages:

[0012] The controller uses an FPGA as its core for data acquisition and processing, saving space for peripheral circuits. It also has good portability and scalability, and is versatile.

[0013] The controller features extremely high angular displacement measurement accuracy, employing a REXA ultra-high precision absolute circular grating sensor with two RESOLUTEs. TM The reading head achieves ultra-high precision.

[0014] The controller can achieve rotor levitation and stability by precisely controlling the current in the magnetic bearing coil, thereby avoiding friction and wear in traditional mechanical bearings, improving the accuracy and efficiency of unloading gravity, and reducing system losses. Attached Figure Description

[0015] Figure 1 A flowchart illustrating the gravity unloading controller for a Lorentz force magnetic levitation omnidirectional stabilization platform. Specific implementation methods

[0016] The specific steps for unloading gravity using a Lorentz force magnetic levitation omnidirectional stabilizing platform gravity unloading controller are as follows:

[0017] Step 1: When the attitude movement of the platform payload compartment causes a change in the center of gravity, the lower-level FPGA sends a request position signal MA to the photoelectric encoder. The photoelectric encoder located on the magnetic bearing measures the angular displacement and transmits the obtained angular displacement data to the lower-level FPGA as an SLO signal.

[0018] Step 2: The host PC sends sensor data read / write commands to the lower-level FPGA via the interface. The lower-level FPGA receives the commands and returns the corresponding data to the host PC. The host PC calculates the amount of current required to unload the gravity using a custom formula.

[0019] Step 3: The host PC records and exports the sensor data parsed in Step 2 for further analysis and reporting. The host PC then sends the corresponding control current command to the programmable power supply based on the calculated current magnitude.

[0020] Step 4: After receiving the instruction, the programmable power supply's internal microprocessor or control system parses the instruction. If the instruction is valid and the power status allows, the programmable power supply will execute the corresponding current adjustment operation. After completing the current adjustment, the programmable power supply will send a response signal to the host PC to confirm that the instruction has been executed and report the current power status.

[0021] Step 5: The adjusted current passes through the magnetic bearing coil to readjust and balance the shifted center of gravity of the platform, achieving high-precision gravity unloading control in any posture.

[0022] Furthermore, in step two, the host computer (PC) converts the collected displacement data. The angular displacement measured by the photoelectric encoder is denoted as α, the weight of the load stage is m, the force component along the load stage direction is F1, and the force component perpendicular to the load stage direction is F2. According to the formula...

[0023] F1=sinα×mg (10)

[0024] F2=cosα×mg (11)

[0025] F = BIL (12)

[0026] From the Lorentz force formula, we have

[0027] but

[0028]

[0029]

[0030] The linear displacement sensor's measuring probes are placed at both ends, meaning the measured displacement values ​​are X1 and X2, and the actual displacement is X3.

[0031]

[0032] There are also

[0033] F = ma (16)

[0034]

[0035] but

[0036]

Claims

1. A gravity unloading controller for a Lorentz force magnetic levitation omnidirectional stabilizing platform, mainly comprising: The system comprises a host PC, a slave FPGA, a programmable DC power supply, a photoelectric encoder, a linear displacement sensor, an AD conversion module, and a Lorentz force magnetic levitation omnidirectional stabilization platform; its features are: The lower-level FPGA is connected to the photoelectric encoder disk and is used to send an M clock signal MA requesting position information to the photoelectric encoder disk and receive a data signal SLO. The lower-level FPGA and the photoelectric encoder disk communicate through the BISS protocol, which has a high response speed and communication rate. The photoelectric encoder disk is connected to the main control board through a DB9 interface. The MA signal sent by the lower-level FPGA is converted from TTL level to differential signal and output to the photoelectric encoder disk. Then, the SLO signal returned by the photoelectric encoder disk is processed by the chip and converted from differential signal to TTL level and input to the FPGA. The lower-level FPGA is connected to the linear displacement sensor via an AD conversion module to receive the displacement signal output by the linear displacement sensor. A signal conditioning circuit is designed to condition the signal output by the linear displacement sensor, including amplification and filtering, to adapt to the input range and requirements of the AD conversion module. The AD conversion module converts the conditioned analog signal into a digital signal and outputs the digital signal, which is then transmitted to the lower-level FPGA via the SPI interface. The host PC and the slave FPGA are connected via Ethernet for signal exchange. The host PC sends sensor data read / write commands to the slave FPGA through an interface. The slave FPGA receives the commands and returns the corresponding data to the host PC. The host PC calculates the current required to unload the gravity using a custom formula. The programmable DC power supply is connected to the host computer PC via a DB9 serial port cable. Based on the selected communication protocol and instruction format, a control instruction for setting the power supply output current is constructed, and the host computer software sends the control instruction to the programmable DC power supply. The working steps of the gravity unloading controller are as follows: Step 1: When the attitude movement of the platform payload compartment causes a change in the center of gravity, the lower-level FPGA sends a request position signal MA to the photoelectric encoder. The photoelectric encoder located on the magnetic bearing measures the angular displacement and transmits the obtained angular displacement data to the lower-level FPGA as an SLO signal. Step 2: The host PC sends sensor data read / write commands to the slave FPGA via the interface. The slave FPGA receives the commands and returns the corresponding data to the host PC. The host PC calculates the current required to unload the gravity using a custom formula. Step 3: The host computer PC records and exports the sensor data parsed in Step 2 for further analysis and reporting. The host computer PC sends the corresponding control current command to the programmable DC power supply based on the calculated current magnitude. Step 4: After receiving the instruction, the programmable DC power supply's internal microprocessor or control system will parse the instruction. If the instruction is valid and the power status allows it, the programmable DC power supply will perform the corresponding current adjustment operation. After completing the current adjustment, the programmable DC power supply will send a response signal to the host PC to confirm that the instruction has been executed and report the current power status. Step 5: The adjusted current passes through the magnetic bearing coil to readjust and balance the shifted center of gravity of the platform, achieving high-precision gravity unloading control under any posture.

2. The Lorentz force magnetic levitation omnidirectional stabilizing platform gravity unloading controller according to claim 1, characterized in that: In step two, the host computer (PC) converts the collected displacement data. The angular displacement measured by the photoelectric encoder is denoted as α, the weight of the load stage is m, the force component along the load stage direction is F1, and the force component perpendicular to the load stage direction is F2. According to the formula... (1) (2) From the Lorentz force formula, we have (3) but (4) (5) The linear displacement sensor's measuring probes are placed at both ends, meaning the measured displacement values ​​are X1 and X2, and the actual displacement is X3. (6) There are also (7) (8) but (9)。 3. The Lorentz force magnetic levitation omnidirectional stabilization platform gravity unloading controller according to claim 1, characterized in that... An optical encoder disk is used as an angular displacement sensor.

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