Miniaturized three-axis driver and miniaturized three-axis driving method

Abstract

The invention provides a miniaturized three-axis driver, which comprises an SOC core board, a control board and a driving board, and is characterized in that the SOC core board, the control board and the driving board are stacked from top to bottom and are connected through inter-board plug-ins; the SOC core board located on the upper layer is used for completing program tasks of a system three-closed-loop control algorithm, FOC coordinate transformation, SVPWM operation, position acquisition operation, current acquisition operation and serial port communication. The control board located in the middle layer is used for completing a position acquisition circuit, a current ADC acquisition circuit, a serial port, a CAN and an internet access communication circuit; the driving plate positioned on the lower layer drives a power MOS tube switch to be switched on so as to provide three-phase sinusoidal current for a direct-drive motor of the rotary table; according to the three-axis driver, the upper plate, the middle plate and the lower plate are connected in an inserted mode, on the premise that the driving function is guaranteed, the size and the weight of the three-axis driver are greatly reduced, meanwhile, the replaceable design of domestic and imported devices is achieved, the precision is high, the cost is low, and the unification of hardware is achieved to a certain extent.

Description

Technical Field

[0001] The invention relates to the technical field of high-precision astronomical inertial navigation, and in particular to a miniaturized three-axis driver. Background Art

[0002] In order to meet the needs of miniaturization of celestial navigation in airborne environments, a new miniaturized three-axis driver needs to be developed for this application. Currently, optoelectronic turntables or inertial navigation equipment use DC brushed torque motors and AC permanent magnet synchronous motors as actuators to rotate the shaft system. DC brushed motors are relatively simple to control, and the speed can be controlled by adjusting the given voltage across the motor. Since brushless motor drivers can also drive brushed motors, designing an AC permanent magnet synchronous motor driver can meet many requirements.

[0003] However, the current three-axis drives are generally large in size and are not suitable for miniaturized scenarios such as airborne, and circuit boards will face a wave of localization in the future. Therefore, designing a servo drive control circuit board that is universal and compatible with both imported and domestic products has great engineering significance and can generate greater economic benefits, and is conducive to the unification of servo system hardware. Summary of the invention

[0004] The present invention proposes a miniaturized three-axis driver, which solves the problem in the prior art that there is a lack of a three-axis driver dedicated to the field of high-precision astronomical inertial guidance. The technical solution of the present invention is implemented as follows:

[0005] A miniaturized three-axis driver comprises a SOC core board, a control board and a drive board, wherein the SOC core board, the control board and the drive board are stacked from top to bottom, and the layers are connected by indirect board plug-ins;

[0006] The SOC core board located at the upper layer is used to complete the system three-loop control algorithm, FOC coordinate transformation, SVPWM operation, position acquisition operation, current acquisition operation, and serial communication program tasks;

[0007] The control board located in the middle layer is used to complete the position acquisition circuit, current ADC acquisition circuit, serial port, CAN, and network port communication circuits, and at the same time, the PWM control signal of the SOC core board is transmitted to the driver board after level isolation;

[0008] The driving board located at the lower layer is used to complete the isolated PWM control signal sent by the receiving control board, and drive the power MOS tube switch to turn on to provide a three-phase sinusoidal current for the direct drive motor of the turntable, and the current amplitude is controlled by the closed-loop control of the control board.

[0009] As a preferred technical solution, the SOC core board integrates a drive unit submodule, a current acquisition submodule, an encoder feedback interface submodule, a serial communication submodule and an I\O output submodule to realize the function of simultaneously driving three permanent magnet synchronous motors or DC brushed motors.

[0010] As a preferred technical solution, the encoder feedback interface submodule is compatible with BISS protocol photoelectric encoders, circular gratings, time gratings and differential ABZ incremental encoder interfaces.

[0011] As a preferred technical solution, a Hall chip is used for current sampling.

[0012] As a preferred technical solution, the analog-to-digital converter uses a dedicated customized chip that is compatible with the AD7606 chip.

[0013] A miniaturized three-axis driving method uses the above-mentioned miniaturized three-axis driver, and comprises the following steps: the control board receives external instructions, the SOC core board completes speed closed loop, position closed loop and current closed loop or torque closed loop, the drive board receives the isolated PWM control signal sent by the control board, drives the power MOS tube switch to turn on to provide a three-phase sinusoidal current for the direct drive motor of the turntable, and after the motor body and encoder output, the current closed loop or torque closed loop is feedback-regulated by phase current sampling, and the position closed loop and speed closed loop are regulated by position feedback.

[0014] As a preferred technical solution, position feedback obtains the rotational speed through position differential and thus realizes the adjustment of the speed closed loop.

[0015] Compared with the existing technology, this solution has the following beneficial effects: by adopting the upper, middle and lower three-board connection form in the structure, the volume and weight of the three-axis drive are greatly reduced while ensuring the driving function, and at the same time, the domestic and imported components are designed to be interchangeable, with high precision and low cost, and hardware unification is achieved to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a structural block diagram of a miniaturized three-axis driver of the present invention;

[0018] Figure 2A schematic diagram of the working process of a servo system using the miniaturized three-axis driver of the present invention;

[0019] Figure 3 It is a schematic diagram of the multi-layer structure of a miniaturized three-axis actuator of the present invention.

[0020] Description of reference numerals:

[0021] 1. Core board; 2. Control board; 3. Driver board. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Reference Figure 1 and Figure 3 The structure adopts the upper, middle and lower three-board plug-in form, with the control acquisition board 2 in the middle, the upper board is the SOC core board 1, and the lower board is the power drive board 3. The SOC core board mainly completes the system's three closed-loop control algorithms, FOC coordinate transformation, SVPWM operation, position acquisition operation, current acquisition operation, serial communication and other program operation tasks. The control acquisition board and the SOC core board mainly realize the position acquisition circuit, current ADC acquisition circuit, serial communication circuit, and complete the system's three closed-loop control algorithms, coordinate transformation, SVPWM operation and other FOC control processes. The power drive board mainly completes the function of driving the MOS tube to control the three-phase voltage of the motor through the isolation module using the PWM wave sent by the SOC.

[0024] Among them, the miniaturized three-axis driver is equipped with Xilinx's Zynq series core board (also compatible with Fudan Micro's domestic SoC chip core board), integrating the required drive unit, current acquisition, encoder feedback interface, serial communication, IO output and other sub-modules, which can realize the functions of driving 3 permanent magnet synchronous motors or DC brushed motors at the same time. The feedback interface is compatible with the BISS protocol photoelectric encoder, circular grating, time grating and differential ABZ incremental encoder interface. The current sampling adopts Hall chip, which is not only domestically produced but also replaces the imported chip in situ. The analog-to-digital converter (ADC) also adopts the domestically produced chip of AD7606 chip compatible with imports. PWM isolation is stable and reliable. In order to drive more power and reduce heat generation within a limited PCB area, a high-performance small package MOS power tube with low on-resistance Rds is selected as the switch tube. Under the condition of continuous peak 10A high current and close to 100% duty cycle, the heat generation is almost negligible.

[0025] The miniaturized three-axis drive mainly receives instructions sent by the external system, collects intermediate information such as position, speed, current, etc. in real time as required, and completes closed-loop control of position, speed, current (DC brushed motors can be without current loop) to achieve a servo response with certain dynamic capabilities.

[0026] By adopting the upper, middle and lower three-board connection structure, the size and weight of the three-axis driver are greatly reduced while ensuring the driving function. At the same time, the design is interchangeable between domestic and imported components, with high precision and low cost, and hardware unification is achieved to a certain extent.

[0027] According to the servo workflow, the module needs to have the following functions:

[0028] (1) Strong computing power to meet the implementation of 3-way field-oriented control (FOC) algorithm;

[0029] (2) Angle acquisition function of 3-axis motor;

[0030] (3) 6-channel current acquisition function for 3-axis motors with high sampling resolution;

[0031] (4) Multi-channel RS422 communication, with position feedback, speed feedback of inertial devices such as fiber optic gyroscopes, and interfaces for receiving command angles and feedback of angle measurements;

[0032] (5) MOS tube driving circuit;

[0033] (6) The isolation circuit can isolate the power side from the low-voltage side;

[0034] The specific closed-loop adjustment process is as follows:

[0035] Position closed loop: The command position received from the user is used as the input of the position closed loop, and the current position collected by the time-grid angle sensor is used as the feedback value. PID calculation is performed to obtain the command speed as the input of the speed closed loop.

[0036] Speed ​​closed loop: accept the command speed calculated by the position closed loop as the input of the speed closed loop, differentiate the current position and the previous position collected by the time-grid angle sensor to obtain the current speed as the feedback value, perform PID calculation, and obtain the command current (torque) as the input of the current (torque) closed loop.

[0037] Current (torque) closed loop: accepts the command current (torque) calculated by the speed closed loop as the current (torque) input, uses the current ADC acquisition circuit to collect the current (calculated torque) as the feedback value, performs PID calculation, and obtains the PWM drive signal.

[0038] The PWM drive signal drives the MOS tube, driving the motor to reach the user's command position.

[0039] Permanent magnet synchronous motor is: position closed loop - speed closed loop - current closed loop.

[0040] The brushed DC motor has: position closed loop - speed closed loop - torque closed loop.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A miniaturized three-axis actuator, characterized in that: It includes a SOC core board, a control board and a driver board, wherein the SOC core board, the control board and the driver board are stacked from top to bottom, and the layers are connected by indirect board plug-ins; The SOC core board located at the upper layer is used to complete the system three-loop control algorithm, FOC coordinate transformation, SVPWM operation, position acquisition operation, current acquisition operation, and serial communication program tasks; The control board located in the middle layer is used to complete the position acquisition circuit, current ADC acquisition circuit, serial port, CAN, and network port communication circuits, and at the same time, the PWM control signal of the SOC core board is transmitted to the driver board after level isolation; The driving board located at the lower layer is used to complete the isolated PWM control signal sent by the receiving control board, and drive the power MOS tube switch to turn on to provide a three-phase sinusoidal current for the direct drive motor of the turntable, and the current amplitude is controlled by the closed-loop control of the control board.

2. A miniaturized three-axis actuator as claimed in claim 1, characterized in that: The SOC core board integrates a drive unit submodule, a current acquisition submodule, an encoder feedback interface submodule, a serial communication submodule and an I\O output submodule, and is used to realize the function of simultaneously driving three permanent magnet synchronous motors or DC brushed motors.

3. A miniaturized three-axis actuator as claimed in claim 2, characterized in that: The encoder feedback interface submodule is compatible with BISS protocol photoelectric encoders, circular gratings, time gratings, and differential ABZ incremental encoder interfaces.

4. A miniaturized three-axis actuator as claimed in claim 2, characterized in that: The current sampling adopts a Hall chip.

5. A miniaturized three-axis actuator as claimed in claim 2, characterized in that: The analog-to-digital converter uses a dedicated custom chip that is compatible with the AD7606 chip.

6. A miniaturized three-axis driving method, characterized in that: A miniaturized three-axis driver as described in any one of claims 1 to 5 above is used, comprising the following steps: the control board receives external instructions, the SOC core board completes the speed closed loop, position closed loop and current closed loop or torque closed loop, the drive board receives the isolated PWM control signal sent by the control board, drives the power MOS tube switch to turn on to provide a three-phase sinusoidal current for the direct drive motor of the turntable, and after the motor body and encoder output, the current closed loop or torque closed loop is feedback-adjusted by phase current sampling, and the position closed loop and speed closed loop are adjusted by position feedback.

7. A miniaturized three-axis driving method as claimed in claim 6, characterized in that: The position feedback obtains the rotation speed by means of the position difference and thus realizes the regulation of the speed closed loop.

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