Servo steering engine capable of eliminating back electromotive force

Abstract

The invention provides a servo steering engine capable of eliminating reverse electromotive force. The servo steering engine comprises a servo driver, a servo motor, a reverse electromotive force detection and elimination circuit and a speed reduction transmission device. By integrating the back electromotive force detection and elimination circuit and the servo steering engine, the back electromotive force is monitored and eliminated in real time, system voltage fluctuation caused by the back electromotive force is effectively avoided, and therefore the stability and reliability of the whole unmanned helicopter system are improved. By eliminating the reverse electromotive force, damage to a steering engine driving circuit and other electronic equipment caused by overhigh electromotive force is prevented, the service life of the equipment is prolonged, and the maintenance cost is reduced. Due to the elimination of the reverse electromotive force, the servo motor can still keep excellent response speed in a high-speed and frequent reversing environment, and the requirement of the unmanned helicopter for quick response performance is met.

Description

Technical Field

[0001] The present invention relates to the technical field of servo actuators for unmanned helicopters, and specifically to a servo actuator capable of eliminating back electromotive force. Background Art

[0002] In the field of unmanned helicopters, servo actuators are key components for achieving precise control. As Figure 1 shown, traditional servo actuators generally consist of a servo driver, a servo motor, a speed reduction and transmission device, a ball screw and a slider, a push rod and a joint shaft, a linear displacement type variable resistor sensor, etc. After receiving a control signal, the actuator drives the motor to rotate, reduces the speed and increases the torque through a reducer, and then pushes the ball screw and the slider to perform linear motion to achieve precise control of the unmanned helicopter. The linear displacement type variable resistor sensor converts the position information of the ball screw and the slider into an electrical signal and feeds it back to the control system.

[0003] However, existing servo actuators have serious problems when applied to unmanned helicopters. Since the control frequency of unmanned helicopters is usually above 100 Hz, this requires the actuator to have an extremely high response speed, that is, a fast response characteristic of up to 600° / s. Under such high-speed and frequently commuting motion conditions, the servo motor is prone to generating back electromotive force. With the increase in the motor motion speed and the sudden change of the load characteristics, the amplitude of the back electromotive force may be several times that of the system voltage, which will have a serious impact on the system voltage of the unmanned aerial vehicle and may even cause damage to the actuator drive circuit and other devices on the unmanned aerial vehicle. Summary of the Invention

[0004] The object of the present invention is to provide a servo actuator capable of eliminating back electromotive force, so as to solve the problem that in the prior art, under fast motion, frequent commutation and large-load motion of the servo motor, the servo motor will generate back electromotive force, and with the increase in the motor motion speed and the sudden change of the load characteristics, the generated back electromotive force will be higher than several times the system voltage, which will have a great impact on the system voltage of the unmanned aerial vehicle and may seriously burn out the drive circuit of the actuator itself and other devices externally connected to the unmanned aerial vehicle system.

[0005] To achieve the above object, the present invention provides the following technical solution: The present invention provides a servo actuator capable of eliminating back electromotive force, including a servo driver, a servo motor, a back electromotive force detection and elimination circuit, and a speed reduction and transmission device;

[0006] The servo driver is powered by the system and is used to drive the servo motor to move. The servo motor is connected to the speed reduction and transmission device through gear transmission. The back electromotive force detection and elimination circuit is connected to the servo motor and is used to detect the back electromotive force generated by the servo motor in real time;

[0007] The speed reduction transmission device is used to reduce the speed of the servo motor and transmit it to the load end to achieve the control of the load.

[0008] Preferably, the servo driver consists of a microcontroller unit (MCU) and a drive circuit. The microcontroller unit (MCU) controls the drive circuit through the microcontroller unit (MCU) to drive the servo motor.

[0009] Preferably, the back electromotive force detection and elimination circuit includes a back electromotive force detection circuit and a back electromotive force elimination circuit. The back electromotive force detection circuit is used to detect the voltage value of the system power supply. When the voltage value is higher than the threshold set by the system, the microcontroller unit (MCU) will obtain a back electromotive force signal. The back electromotive force detection circuit adopts a sampling circuit with an operational amplifier plus a high-speed isolation optocoupler to isolate the external system voltage from the power supply of the microcontroller unit (MCU), which not only improves the sampling safety but also conforms to the high-speed response characteristics of the system.

[0010] The method of the back electromotive force elimination circuit includes adding an RCD absorption circuit with MOS tube control to the three-phase bus of the motor, and correspondingly reducing the duty cycle of the drive signal sent by the microcontroller unit (MCU) to the microcontroller unit (MCU).

[0011] Preferably, the microcontroller unit (MCU) is used to control the operation of the back electromotive force elimination circuit to eliminate the back electromotive force in the system.

[0012] Preferably, the servo driver includes a control algorithm for detecting the system bus voltage, controlling the normal operation of the back electromotive force elimination circuit, and softening the control PWM signal when the back electromotive force is generated.

[0013] Preferably, the speed reduction transmission device feeds back the position signal to the microcontroller unit (MCU) to form a closed-loop control.

[0014] The present invention has at least the following beneficial effects:

[0015] A servo actuator capable of eliminating the back electromotive force provided by the present invention realizes the real-time monitoring and elimination of the back electromotive force by integrating the back electromotive force detection and elimination circuit, effectively avoiding the system voltage fluctuation caused by the back electromotive force, thereby improving the stability and reliability of the entire unmanned helicopter system. Eliminating the back electromotive force not only prevents the damage of the servo drive circuit and other electronic devices caused by excessive electromotive force, but also extends the service life of the equipment and reduces the maintenance cost.

[0016] Due to the elimination of the back electromotive force, the servo motor can still maintain excellent response speed in high-speed and frequent commutation environments, meeting the requirements of the unmanned helicopter for fast response performance.

[0017] Integrating the servo driver, servo motor, back electromotive force detection and elimination circuit into a single servo actuator simplifies the system architecture, reduces the dependence on external protection measures, and lowers the complexity and cost of the system. The position signal is fed back to the microcontroller unit (MCU) through a speed reduction transmission device, forming a closed-loop control system, achieving precise control of the movement of the unmanned helicopter and improving the control accuracy.

[0018] The combination of the control algorithm built into the servo driver and the back electromotive force elimination circuit provides dual protection of software and hardware, ensuring effective elimination of the back electromotive force in various working environments, enhancing the robustness of the system. When the back electromotive force is generated, by optimizing the control PWM signal, the impact on the system is further reduced, ensuring the smooth operation of the actuator and the accuracy of control, demonstrating broad application potential. Brief Description of the Drawings

[0019] Figure 1 Schematic diagram of the existing servo mechanism;

[0020] Figure 2 Schematic diagram of the servo actuator of the present invention;

[0021] Figure 3 Schematic diagram of the back electromotive force detection circuit;

[0022] Figure 4 Schematic diagram of the back electromotive force absorption circuit;

[0023] Figure 5 Flowchart of the servo drive control algorithm of the present invention;

[0024] Figure 6 Flowchart of the control algorithm for removing the back electromotive force. Detailed Description of the Invention

[0025] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in this specification in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0026] Embodiment

[0027] As Figure 2 、 Figure 3 、 Figure 4 、Figure 5 and Figure 6 As shown in Figure 6 , a servo steering gear capable of eliminating back electromotive force includes a servo driver, a servo motor, a back electromotive force detection and elimination circuit, and a speed reduction transmission device. The servo driver is powered by the system and is used to drive the servo motor to move. The servo motor is connected to the speed reduction transmission device through gear transmission. The speed reduction transmission device is used to reduce the speed of the servo motor and transmit it to the load end to achieve the control of the load. The back electromotive force detection and elimination circuit is connected to the servo motor and is used to detect the back electromotive force generated by the servo motor in real time and take measures to eliminate this electromotive force.

[0028] The servo driver consists of a microcontroller unit (MCU) and a drive circuit. The microcontroller unit (MCU) drives the servo motor by controlling the drive circuit. The microcontroller unit (MCU) is responsible for controlling the operation of the back electromotive force elimination circuit to eliminate the back electromotive force in the system.

[0029] The back electromotive force detection and elimination circuit includes a back electromotive force detection circuit and a back electromotive force elimination circuit. The back electromotive force detection circuit is used to detect the voltage value of the system power supply.

[0030] As Figure 3 shown in Figure 3 , the back electromotive force detection circuit consists of a resistor voltage division circuit, a pre-stage operational amplifier circuit, an optocoupler isolation circuit, and a post-stage operational amplifier circuit.

[0031] The back electromotive force will be generated on the bus voltage. Using the resistor voltage division circuit, the high voltage is converted into a low voltage and then transmitted to the pre-stage operational amplifier U1A (LM2904). The voltage processed by the pre-stage operational amplifier is sent to the input terminal of the isolation optocoupler N20 (HCNR200). The output terminal of the isolation optocoupler N20 (HCNR200) is connected to the post-stage operational amplifier U1B (LM2904). The further amplified voltage AD1 can be directly connected to the MCU. Through this detection circuit, the real-time monitoring of the back electromotive force can be realized, the voltage acquisition of the high-voltage bus is completed, and the isolation between the high-voltage ground signal (GND_D) and the low-voltage ground signal (GND) is achieved, ensuring the safety of the system.

[0032] When the voltage value is higher than the threshold set by the system, the microcontroller unit (MCU) will obtain the back electromotive force signal. The back electromotive force detection circuit adopts a sampling circuit of an operational amplifier plus a high-speed isolation optocoupler to achieve the isolation of the external system voltage and the power supply of the microcontroller unit (MCU), improve the sampling safety, and meet the high-speed response characteristics of the system.

[0033] The method of the back electromotive force elimination circuit includes adding an RCD absorption circuit with MOS transistor control to the three-phase bus of the motor and correspondingly reducing the duty cycle of the driving signal sent by the microcontroller unit (MCU).

[0034] As Figure 4 shown, in the back electromotive force absorption circuit, for the three-phase driving signals PHA, PHB, and PHC provided by the driving circuit to the motor, two paths of MOSFETs and RCD absorption circuits are respectively connected in parallel between PHA and PHB, and between PHB and PHC. The control terminals Contol1 and Contol2 of these two paths of MOSFETs are respectively connected to the MCU control pins in the driver. When the detection circuit detects the appearance of back electromotive force in the system, the MCU will control Contol1 and Contol2 according to a predetermined timing sequence to enable the RCD absorption circuit to absorb the back electromotive force.

[0035] The servo driver includes a control algorithm for detecting the system bus voltage and controlling the normal operation of the back electromotive force elimination circuit. When the back electromotive force is generated, the control algorithm softens the control of the PWM signal to reduce the impact on the system.

[0036] The reduction gear transmits the position signal back to the microcontroller unit (MCU) to form a closed-loop control. The closed-loop control can achieve precise control of the movement of the unmanned helicopter and improve the control accuracy.

[0037] As Figure 5 、 Figure 6 shown, it shows the flow chart of the servo drive control algorithm and the flow chart of the control algorithm for removing the back electromotive force.

[0038] In the servo motor control algorithm, in addition to the driver applying the PID closed-loop drive control algorithm to the motor itself (as Figure 5 shown), the elimination of the back electromotive force also adopts a closed-loop control strategy (as Figure 6 shown). The microcontroller unit (MCU) uses the back electromotive force detection circuit as the feedback of the system algorithm, and through two ways, namely controlling the algorithm for removing the back electromotive force circuit and optimizing the algorithm for driving the motor, jointly realizes the core algorithm for removing the back electromotive force.

[0039] Install the servo actuator on the unmanned helicopter and start the servo driver through system power supply. After receiving the control signal, the servo driver drives the servo motor to rotate. During the high-speed operation and frequent commutation of the servo motor, the back electromotive force detection and elimination circuit monitors the system bus voltage in real time. The operational amplifier and high-speed isolation optocoupler in the detection circuit work together to ensure the accurate acquisition and safe isolation of voltage signals. When the detected voltage value is higher than the preset threshold, that is, when there is back electromotive force, the microcontroller unit (MCU) responds quickly, softens the PWM signal through the control algorithm, and adjusts the RCD absorption circuit controlled by the MOS tube to effectively absorb and eliminate the back electromotive force, avoiding impact on the system voltage.

[0040] At the same time, the speed reduction and transmission device reduces the speed of the servo motor and transmits it to the load end to achieve precise adjustment of the flight attitude of the unmanned helicopter. During this process, the position sensor of the speed reduction and transmission device feeds back the position signal to the microcontroller unit (MCU) in real time to form a closed-loop control system. The closed-loop control strategy not only improves the control accuracy but also enhances the stability and reliability of the system.

[0041] The servo actuator of the present invention integrates the back electromotive force detection and elimination circuit, realizes real-time monitoring and elimination of the back electromotive force, effectively avoids the system voltage fluctuation caused by the back electromotive force, and improves the stability and reliability of the entire unmanned helicopter system. The servo motor can still maintain excellent response speed in the environment of high speed and frequent commutation, meeting the requirements of the unmanned helicopter for fast response performance. In addition, by integrating the servo driver, servo motor, back electromotive force detection and elimination circuit inside a single servo actuator, the system architecture is simplified, the dependence on external protection measures is reduced, and the complexity and cost of the system are lowered. The combination of the control algorithm built into the servo driver and the back electromotive force elimination circuit provides double protection of software and hardware, ensuring effective elimination of the back electromotive force in various working environments.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other changes in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A servo actuator capable of eliminating back electromotive force, characterized in that: It includes a servo drive, a servo motor, a reverse electromotive force detection and elimination circuit, and a reduction transmission device; The servo driver is powered by the system and is used to drive the servo motor to move. The servo motor is connected to the reduction transmission device through a gear transmission. The back electromotive force detection and elimination circuit is connected to the servo motor and is used to detect the back electromotive force generated by the servo motor in real time. The reduction transmission device is used to reduce the rotation speed of the servo motor and transmit it to the load end to achieve load control.

2. A servo actuator capable of eliminating back electromotive force according to claim 1, characterized in that: The servo driver is composed of a microcontroller unit (MCU) and a driving circuit. The microcontroller unit (MCU) controls the driving circuit through the microcontroller unit (MCU) to drive the servo motor.

3. A servo actuator capable of eliminating back electromotive force according to claim 2, characterized in that: The reverse electromotive force detection and elimination circuit includes a reverse electromotive force detection circuit and a reverse electromotive force elimination circuit, and the reverse electromotive force detection circuit is used to detect the voltage value of the system power supply; The method of the reverse electromotive force elimination circuit includes adding an RCD absorption circuit with MOS tube control in the three-phase bus of the motor, and correspondingly reducing the duty cycle of the driving microcontroller unit (MCU) signal sent by the microcontroller unit (MCU).

4. A servo actuator capable of eliminating back electromotive force according to claim 3, characterized in that: The microcontroller unit (MCU) is used to control the operation of the reverse electromotive force elimination circuit, thereby eliminating the reverse electromotive force in the system.

5. A servo actuator capable of eliminating back electromotive force according to claim 4, characterized in that: The servo drive includes a control algorithm for detecting the system bus voltage and controlling the back electromotive force elimination circuit to work normally, and softening the control PWM signal when generating back electromotive force.

6. A servo actuator capable of eliminating back electromotive force according to claim 5, characterized in that: The reduction transmission device feeds back the position signal to a microcontroller unit (MCU) to form a closed-loop control.

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