KR102141417B1 - Unmanned aerial vehicle motor speed controller and control method thereof - Google Patents

Abstract

An unmanned aerial vehicle (UAV) motor speed control device including a plurality of motors according to an embodiment receives an PWM (Pulse Width Modulation) signal from a flight controller and transmits a duty cycle to the plurality of motors. And a microprocessor unit that calculates a duty cycle by using a negative pulse width modulation (PWM) signal value and corrects the duty cycle in consideration of a battery voltage.

Description

A device and method for controlling the motor speed of an unmanned aerial vehicle{UNMANNED AERIAL VEHICLE MOTOR SPEED CONTROLLER AND CONTROL METHOD THEREOF}

The present invention relates to an apparatus and method for controlling a motor speed of an unmanned aerial vehicle, and more particularly, to an apparatus and method for controlling a motor speed in consideration of an effect of a voltage drop of a battery.

Unmanned aerial vehicles have been used in various fields in recent years due to their ease of control and high utilization. Related markets are rapidly growing, such as using unmanned aerial vehicles not only in film and broadcasting, but also in global distribution companies. However, as the scope of use expands to the private sector, human and property damage may occur due to inexperienced operation or malfunction.

In addition, unmanned aerial vehicles require accurate flight capabilities to perform missions. For these reasons, the flight stability of unmanned aerial vehicles has become more important. The unmanned air vehicle has an unstable flight because it cannot maintain a constant motor speed because the motor speed changes according to the voltage change of the battery. Therefore, in order to stabilize the flight of the unmanned aerial vehicle, it is necessary to control the speed of the motor in consideration of the voltage fluctuation of the battery.

Flight stability of an unmanned vehicle means flying stably while maintaining the balance and altitude of the unmanned vehicle through a posture control algorithm. One of the major causes of deteriorating flight stability of an unmanned aerial vehicle is a change in motor speed due to a drop in the battery voltage of the unmanned aerial vehicle. However, existing methods to cope with the battery voltage fluctuation problem are mainly hardware-dependent and require additional experimentation or modification due to hardware changes.

Korean Application No. 10-1998-0006904

An object of the present invention is to provide a motor control apparatus and method capable of stably operating by reducing the range of speed variation of an actual motor regardless of the type of motor by reducing the output range of the duty cycle through additional control in consideration of voltage fluctuation.

An apparatus for controlling a motor speed of an unmanned aerial vehicle (UAV) including a plurality of motors according to an embodiment of the present invention receives a pulse width modulation (PWM) signal from a flight controller and performs a duty cycle on the plurality of motors. It may include a microprocessor unit for calculating a duty cycle using the interface unit to transmit and the pulse width modulation (PWM) signal value, and correcting the duty cycle in consideration of the voltage of the battery.

According to an embodiment, the microprocessor unit may compare a measured voltage value with a reference voltage value, and correct a duty cycle according to the comparison result.

According to an embodiment, the microprocessor unit receives a voltage and a current value, and when the voltage is greater than a predetermined reference voltage, generates a corrected voltage and current value and performs PI control reflecting an error in the current value. The duty cycle can be corrected.

According to one embodiment, the motor speed control device of the unmanned aerial vehicle may be installed in the form of a firmware in the electronic transmission of the unmanned aerial vehicle.

According to an embodiment of the present invention, a method of controlling a motor speed of an unmanned aerial vehicle (UAV) including a plurality of motors includes receiving a PWM (Pulse Width Modulation) signal from a flight controller, and the PWM signal Calculating a duty cycle for, receiving a measured voltage/current value from a battery, correcting the calculated duty cycle in consideration of the measured voltage/current value, and calibrating the corrected values to the plurality of motors And delivering a duty cycle.

According to an embodiment, correcting the calculated duty cycle in consideration of the measured voltage/current value may include comparing the measured voltage value with a reference voltage value, and correcting the duty cycle according to the comparison result. It may include.

According to an embodiment, the step of correcting the duty cycle may include generating a corrected voltage and current value when the voltage value is greater than a predetermined reference voltage value by receiving a voltage and current value of the battery and generating a corrected voltage and current value. And correcting the duty cycle by performing PI control reflecting the error.

According to one embodiment, the method for controlling the motor speed of the unmanned aerial vehicle may be installed in the form of a firmware in an electronic transmission of the unmanned aerial vehicle.

An apparatus and method for controlling a motor speed of an unmanned aerial vehicle according to an embodiment of the present invention have an effect of enabling stable flight regardless of the type of motor used for the unmanned aerial vehicle.

1 is a graph showing a discharge voltage graph of a lithium-polymer battery.
2 is a block diagram illustrating the configuration of a general unmanned aerial vehicle.
3 is a block diagram illustrating the configuration of a motor speed controller of an unmanned aerial vehicle according to an embodiment.
4 is a flow chart for explaining a method of controlling a motor speed of an unmanned aerial vehicle according to an embodiment.
5 is a flowchart for explaining a method of calculating an actual duty in a method for controlling a motor speed of an unmanned aerial vehicle according to an embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The same reference numerals in each drawing denote the same members.

Various modifications may be made to the embodiments described below. The examples described below are not intended to be limiting with respect to the embodiments, and should be understood to include all modifications, equivalents, or substitutes thereof.

The terms used in the examples are only used to describe specific examples, and are not intended to limit the examples. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “include” or “have” are intended to indicate that there are features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the embodiment belongs. Terms, such as those defined in a commonly used dictionary, should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

In addition, in the description with reference to the accompanying drawings, the same reference numerals are assigned to the same components regardless of reference numerals, and redundant descriptions thereof will be omitted. In describing the embodiments, when it is determined that detailed descriptions of related known technologies may unnecessarily obscure the subject matter of the embodiments, the detailed descriptions will be omitted.

1 is a graph showing a discharge voltage graph of a lithium-polymer battery.

Referring to FIG. 1, a graph of a discharge voltage of a lithium-polymer battery according to time when flying an unmanned aerial vehicle may be confirmed. Lithium-polymer batteries have a large capacity and a long usage time, and thus are used as a power source for unmanned aerial vehicles.

A fully charged battery will drop in voltage over time. At this time, even though the voltage reduction amount for each time section is different, even if the same throttle signal for the aircraft is given, the speed of the motor changes unstable and the aircraft repeats the ascent and descent. In particular, when the battery voltage is 10.6V or less (7-9 minutes in the box), the voltage drop occurs abruptly, limiting the use of the battery for unmanned aerial vehicles. In an embodiment of the present invention, a 3-cell lithium battery is used, and in this case, the reference voltage may be set in a range of 10.5V to 12.0V in consideration of the discharge rate of the 3-cell lithium battery. In the embodiment of the present invention, the reference voltage is set to 10.5 V, but is not limited thereto, and may be changed according to design and needs.

Therefore, it is necessary to stabilize the flying of the unmanned aerial vehicle by solving the problem of the motor speed fluctuation of the unmanned aerial vehicle due to the battery voltage drop. The proposed methods are mainly hardware dependent or require additional experimentation. According to an embodiment of the present invention, a motor speed control device may be installed in the firmware of the electronic transmission to enable more stable flight.

2 is a block diagram illustrating the configuration of a general unmanned aerial vehicle.

Referring to FIG. 2, in general, an unmanned aerial vehicle may include a flight controller 210, an electronic transmission 220, and a motor 230.

The unmanned aerial vehicle may receive a flight control command signal including a pitch, roll, yaw, and throttle from the remote controller. The control command signal may be processed by a flight controller (Flight Controller 210) corresponding to the main MCU of the unmanned aerial vehicle. The general motor speed control of the unmanned aerial vehicle may be transmitted to the motor 230 through the electronic transmissions (ESC, 220) starting from the flight controller 210.

After calculating and filtering according to the control model, the flight controller calculates a motor speed required for unmanned aerial vehicle flight and transmits a corresponding PWM (Pulse Width Modulation) signal value to the electronic transmission. The duty cycle, which is the ratio of the pulse width to the pulse period, may be calculated by using the PWM signal value and period received from the firmware of the electronic transmission 220. The calculated duty cycle is corrected by computing elements such as voltage, current, and RPM in the firmware of the electronic transmission 220 and can be filtered through a PID controller. The final duty cycle after this processing may be applied to the motor from the electronic transmission 220.

The flight controller 210 also has various control models depending on the type or purpose of use of the unmanned vehicle, and the PWM signal value, which is the final output value, differs depending on the unmanned vehicle because of differences in controllers used therein. Also, because the battery voltage drop is not taken into account, there is a change in motor speed despite the same PWM signal value.

3 is a block diagram illustrating the configuration of a motor speed control device for an unmanned aerial vehicle according to an embodiment.

According to an embodiment, the motor speed control device of the unmanned aerial vehicle may be installed in the form of firmware in the electronic transmission 220. Referring to FIG. 3, the motor speed control device installed in the form of firmware in the electronic transmission 220 may include an interface unit 221 and a microprocessor unit 222.

An apparatus for controlling a motor speed of an unmanned aerial vehicle (UAV) including a plurality of motors according to an embodiment of the present invention receives a pulse width modulation (PWM) signal from a flight controller and performs a duty cycle on the plurality of motors. It may include a microprocessor unit for calculating the duty cycle using the interface unit to transmit and the pulse width modulation (PWM) signal value, and correcting the duty cycle in consideration of the voltage of the battery.

The motor speed control device according to an embodiment may be implemented in the electronic transmission 220. The microprocessor unit 222 of the electronic transmission 220 may calculate the duty cycle using the PWM signal and period received through the interface unit 221 of the electronic transmission 220. At this time, since the generated duty cycle value is a duty cycle value that does not consider voltage and current values, accurate control of the motor speed may not be achieved. Therefore, the microprocessor unit 222 of the electronic transmission 220 may calculate the duty cycle value to be applied to the motor one more time in consideration of the voltage value and the current value in the calculated duty cycle.

The motor speed control device belonging to the electronic transmission 220 may directly affect the duty cycle applied to the actual motor than the flight controller 210. In addition, since the voltage/current value can be reflected in the calculation element used for the correction and filtering of the duty cycle, the battery voltage drop can be considered. The motor speed control device of the electronic transmission 220 compensates for the duty cycle using factors such as voltage/current, and reduces the output range of the duty cycle through additional control in consideration of voltage fluctuations to reduce the actual motor speed. It can be implemented to control. Therefore, when the output range of the duty cycle decreases, the range of speed change of the motor also decreases correspondingly.

According to an embodiment, the microprocessor unit may compare a measured voltage value with a reference voltage value, and correct a duty cycle according to the comparison result.

According to one embodiment, the microprocessor unit receives a voltage and a current value, and when the voltage is greater than a predetermined reference voltage, generates a corrected voltage and current value, and performs PI control reflecting an error in the current value. The duty cycle can be corrected.

According to one embodiment, the motor speed control device of the unmanned aerial vehicle may be installed in the form of a firmware in the electronic transmission of the unmanned aerial vehicle.

4 is a flow chart for explaining a method of controlling a motor speed of an unmanned aerial vehicle according to an embodiment.

Referring to FIG. 4, in step S410, the motor speed control device may receive a pulse width modulation (PWM) signal from the flight controller.

In step S420, the motor speed control device may calculate a duty cycle for the PWM signal.

In step S430, the motor speed control device may receive the voltage/current value measured from the battery.

In step S440, the motor speed control device may correct the calculated duty cycle in consideration of the measured voltage/current value.

In step S450, the motor speed control device may include transmitting the corrected duty cycle to the plurality of motors.

According to an embodiment, the step S440 may include comparing the measured voltage value with a reference voltage value and correcting a duty cycle according to the comparison result.

According to one embodiment, the step (S440), when receiving the voltage and current values of the battery, when the voltage value is greater than a predetermined reference voltage value, generates a corrected voltage and current value, and the error of the current value And correcting the duty cycle by performing the reflected PI control.

According to one embodiment, the method for controlling the motor speed of the unmanned aerial vehicle may be installed in the form of a firmware in an electronic transmission of the unmanned aerial vehicle.

5 is a flowchart illustrating a method of calculating an actual duty cycle in a method for controlling a motor speed of an unmanned aerial vehicle according to an embodiment.

In general, in the actual duty calculation process, the duty value calculated in the duty calculation process is corrected to a duty value to be applied to the motor. At this time, the voltage value and the current value can also be considered and corrected. However, since the voltage drop of the battery is not taken into consideration, the voltage and current values constantly change, and as a result, the actual duty value also changes continuously. Therefore, it is necessary to calculate the actual duty in consideration of the battery voltage drop.

Referring to FIG. 5, in step S510, the motor speed control device may receive the voltage/current value measured in the battery.

In step S520, the motor speed control device may compare the voltage value measured at the battery with a predetermined reference voltage value. Here, the reference voltage is a voltage in a range in which stable operation can be performed among a range of a speed change of a motor according to a voltage in a flying state of an unmanned aerial vehicle, and the stable range may vary according to a battery type or the number of cells.

In step S530, when the voltage value measured in the battery is greater than a predetermined reference voltage value, the motor speed control device may correct the voltage/current value.

In step S540, the motor speed control device performs error calculation of the current value.

According to an embodiment, when the current voltage value is higher than the reference voltage value that ensures flight stability, a voltage value and a current value corresponding to the reference voltage may be used for duty calculation. The motor speed control device can obtain the P control value and the I control value by performing PI control reflecting the error of the current value based on the calculated duty value.

In step S550, the motor speed control device may correct the calculated duty cycle.

According to one embodiment, the motor speed control device finally calculates the duty cycle applied to the actual motor by correcting the duty value with the PI control result value. The duty cycle generated through this process can be applied to the motor to reduce the range of speed change of the motor according to the voltage drop of the battery, thereby enabling stable flight of the unmanned aerial vehicle.

According to an embodiment, a motor speed control device is implemented on the electronic transmission firmware to solve the problem of a motor speed variation of an unmanned aerial vehicle due to a drop in battery voltage. As a result of the experiment, a significant improvement in the amount of motor speed can be achieved to ensure better flight stability of the unmanned aerial vehicle.

The device described above may be implemented with hardware components, software components, and/or combinations of hardware components and software components. For example, the devices and components described in the embodiments include, for example, processors, controllers, arithmetic logic units (ALUs), digital signal processors (micro signal processors), microcomputers, field programmable arrays (FPAs), It may be implemented using one or more general purpose computers or special purpose computers, such as a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. The processing device may run an operating system (OS) and one or more software applications running on the operating system. In addition, the processing device may access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of understanding, a processing device may be described as one being used, but a person having ordinary skill in the art, the processing device may include a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that may include. For example, the processing device may include a plurality of processors or a processor and a controller. In addition, other processing configurations, such as parallel processors, are possible.

The software may include a computer program, code, instruction, or a combination of one or more of these, and configure the processing device to operate as desired, or process independently or collectively You can command the device. Software and/or data may be interpreted by a processing device or to provide instructions or data to a processing device, of any type of machine, component, physical device, virtual equipment, computer storage medium or device. , Or may be permanently or temporarily embodied in the transmitted signal wave. The software may be distributed on networked computer systems, and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the medium may be specially designed and constructed for the embodiments or may be known and usable by those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, and magnetic media such as floptical disks. -Hardware devices specifically configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, etc., as well as machine language codes produced by a compiler. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, although the embodiments have been described by a limited embodiment and drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques are performed in a different order than the described method, and/or the components of the described system, structure, device, circuit, etc. are combined or combined in a different form from the described method, or other components Alternatively, even if replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

220: electronic transmission
221: interface
222: microprocessor section

Claims (8)

In an unmanned aerial vehicle (UAV) motor speed control device comprising a plurality of motors,
An interface unit receiving a PWM (Pulse Width Modulation) signal from the flight controller and transmitting a duty cycle to the plurality of motors; And
A microprocessor unit that calculates a duty cycle using the pulse width modulation (PWM) signal value and corrects the duty cycle in consideration of a battery voltage.
And includes
The microprocessor unit,
Correction of the duty cycle is performed by receiving the measured voltage and current values from the battery and generating corrected voltage and current values when the voltage is greater than a predetermined reference voltage, and performing PID control reflecting the error of the current values to perform correction. and
A motor speed control device for an unmanned aerial vehicle, characterized in that the duty cycle applied to an actual motor is calculated through the corrected duty cycle.
delete delete According to claim 1,
The motor speed control device of the unmanned aerial vehicle,
Motor speed control device for an unmanned aerial vehicle, characterized in that it is installed in the form of a firmware in the electronic transmission of the unmanned aerial vehicle.
In a method for controlling the motor speed of an unmanned aerial vehicle (UAV) comprising a plurality of motors,
Receiving a PWM (Pulse Width Modulation) signal from the flight controller;
Calculating a duty cycle for the PWM signal;
Receiving a measured voltage/current value at the battery;
Correcting the calculated duty cycle in consideration of the measured voltage/current value;
Calculating a duty cycle applied to the actual motor through the corrected duty cycle; And
Transferring the corrected duty cycle to the plurality of motors
Including,
Compensating the duty cycle,
When the voltage and current values of the battery are received and the voltage value is greater than a predetermined reference voltage value, generating a corrected voltage and current value and correcting a duty cycle by performing PID control reflecting an error of the current value A method for controlling the motor speed of an unmanned aerial vehicle.
delete delete The method of claim 5,
The motor speed control method of the unmanned aerial vehicle,
Method for controlling the motor speed of an unmanned aerial vehicle, characterized in that it is installed in the form of a firmware in the electronic transmission of the unmanned aerial vehicle.

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