A propeller rotating speed control method for a turboprop engine of a UAV

Abstract

The present application provides a propeller speed control method for a turboprop engine of a UAV, which comprises a propeller speed drift automatic compensation rule for solving the propeller balance speed drift problem caused by the step loss of the step motor speed selection; the control method further comprises an online calibration method for the relationship between the propeller speed and the number of steps, which can be combined with other ground tests of the engine without running a special ground test program, and the calibration can be completed through simple online operation. The present application solves two major problems of the step motor speed selection structure of the propeller speed regulator of the small and medium-sized turboprop engine of the UAV, and realizes the accurate control of the propeller speed in the UAV mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aviation turboprop engine, in particular to a propeller speed control method for a turboprop engine of a UAV. BACKGROUND

[0002] With the vigorous development of UAV technology, more large-scale military / civil high-end UAVs begin to use turboprop engines as their power source. In order to adapt to the general use of the electric transmission flight control of the UAV, the propeller speed regulator of the turboprop engine has been changed from the original mechanical control system to the electronic control system. The propeller speed regulator adopts the centrifugal flyweight type mechanical hydraulic control structure unchanged, and replaces the original mechanical speed selection lever with a stepping motor for electronic speed selection adjustment. The electronic propeller speed regulator realizes the electronic speed selection control function of the propeller by integrating the functions of the stepping motor, the reverse prop electromagnetic valve, the centrifugal flyweight, and the beta valve, and meets the requirements of the electronic integrated control of the engine and the propeller of the UAV and the electric control requirements of the electric transmission flight control system of the UAV. The electronic controller of the engine receives the power demand instruction issued by the UAV, automatically solves the required propeller speed, and solves the step number required by the stepping motor in the calibration data table according to the propeller speed. The electronic controller sends a stepping instruction to the stepping motor according to the step number result, and the stepping motor runs the corresponding step number to the corresponding speed selection position in the counting mode, so as to select the propeller to work at different speeds. In order to solve the problem that the different parts of the propeller speed regulator have large differences in the step number instructions due to the manufacturing tolerance and the factory debugging test tolerance, a special ground test calibration program is also developed.

[0003] The existing technology does not solve the problem of different degrees of propeller speed deviation caused by the step loss of the stepping motor during the flight of the UAV, and the propeller cannot work at the best working speed and has different degrees of speed drift. In addition, the existing ground test calibration program developed for the problem of large differences in the step number instructions of different parts of the propeller speed regulator has a complicated calibration process, and needs to be repeatedly tested on the ground, which causes waste of human and material resources. SUMMARY

[0004] The present application combines the principle characteristics of the propeller speed regulator and proposes a propeller speed online calibration method and a propeller speed deviation automatic compensation law:

[0005] a) Propeller speed online calibration method: in the ground running test state, the propeller speed of the turboprop engine of the UAV is calibrated to obtain the actual running step number of the speed selection stepping motor corresponding to different propeller speeds, which is stored in the electronic controller as the default step number.

[0006] Preferably, the engine is in the state of ground running test, the UAV operator pushes the power lever to check the engine working condition, when the engine speed ng is in the interval of [86%, 96%], the propeller speed should be between [2000±10] r / min, if the actual propeller speed is lower than this range, it does not meet the requirements, the operator issues the "speed selection motor step increase" instruction 1 time through communication instruction, then the default calibration position of 720 steps corresponding to the [2000±10] r / min speed is increased by 5 steps, at this time the propeller speed will increase slightly, if it still does not meet the requirements, the operator continues to issue the "speed selection motor step increase" instruction, then the speed continues to increase, until the propeller speed is stable between [2000±10] r / min. At this time the UAV operator issues the "2000r / min calibration" communication instruction, then the current speed selection stepper motor actual running step number X1 replaces the default 720 steps and is stored into the electronic controller, the updated X1 step number is used as the default value in subsequent operation.

[0007] Preferably, the engine is in the state of ground running test, the UAV operator pushes the power lever to check the engine working condition, when the engine speed ng is in the interval of [86%, 96%], the propeller speed should be between [2000±10] r / min, if the actual propeller speed is lower than this range, it does not meet the requirements, the operator issues the "speed selection motor step increase" instruction 1 time through communication instruction, then the default calibration position of 720 steps corresponding to the [2000±10] r / min speed is increased by 5 steps, at this time the propeller speed will increase slightly, if it still does not meet the requirements, the operator continues to issue the "speed selection motor step increase" instruction, then the speed continues to increase, until the propeller speed is stable between [2000±10] r / min. At this time the UAV operator issues the "2000r / min calibration" communication instruction, then the current speed selection stepper motor actual running step number X1 replaces the default 720 steps and is stored into the electronic controller, the updated X1 step number is used as the default value in subsequent operation.

[0008] Preferably, for different engines, more different propeller speed calibration requirements can be met by the same method.

[0009] b) the automatic compensation law of the propeller speed: during the flight, the step number of the speed selection instruction CLA is automatically selected as the default value, and if the actual rotating speed monitored does not meet the requirement, the automatic compensation law of the propeller speed is used to control the rotating speed of the propeller, and the specific steps include: if the rotating speed of the propeller is greater than the default value of the step number, the electronic controller automatically sends an instruction to control the step number of the stepping motor to decrease by a certain number of steps; if the rotating speed of the propeller still does not meet the requirement, the electronic controller automatically sends an instruction to control the step number of the stepping motor to decrease by a certain number of steps again, and the same is repeated until the stable range of the rotating speed of the propeller meets the requirement; if the rotating speed of the propeller is less than the default value of the step number, the electronic controller automatically sends an instruction to control the step number of the stepping motor to increase by a certain number of steps; if the rotating speed of the propeller still does not meet the requirement, the electronic controller automatically sends an instruction to control the step number of the stepping motor to increase by a certain number of steps again, and the same is repeated until the stable range of the rotating speed of the propeller meets the requirement.

[0010] The electronic controller is re-powered, the current operation is ended, and the step number of the speed selection instruction is restored to the calibration state.

[0011] Preferably, during the flight, when the engine rotating speed ng is greater than or equal to 96%, the step number X2 of the speed selection instruction CLA is automatically selected as the default value, and when the change rate of the power lever instruction PLA is less than or equal to ±4° / s, it is determined that the rotating speed ns of the propeller should be in the range of [2200±10] r / min after a delay of 5s. If the rotating speed ns of the propeller collected is greater than this range and the time maintained in the range of [2210, 2244] r / min is more than 1s, the electronic controller automatically sends an instruction to control the step number of the stepping motor to decrease by 15 steps. After the adjustment is completed, the range of ns is determined again after a delay of 5s, and if the time maintained in the range of [2210, 2244] r / min is still more than 1s, the electronic controller automatically sends an instruction to control the step number of the stepping motor to decrease by 15 steps again, and the same is repeated until the stable range of the rotating speed meets the requirement of [2200±10] r / min. In order to distinguish the fault of the stepping motor, the maximum decrease of the step number of the stepping motor is not more than 105 steps at this step number;

[0012] If the time maintained in the range of [2244, 2288] is more than 1s, the electronic controller automatically sends an instruction to control the step number of the stepping motor to decrease by 30 steps, so as to more quickly adjust the rotating speed to the stable range, and the same is repeated according to the above steps, and the maximum decrease is not more than 105 steps.

[0013] Preferably, when the engine speed ng≥96%, the speed selection step instruction CLA is automatically selected as X2, and when the power lever PLA instruction change rate is ≤±4° / s, the propeller speed ns is determined to be between [2200±10] r / min after a delay of 5 s. If ns≤2190 r / min is collected for more than 1 s, the electronic controller automatically issues an instruction to control the step motor step number to increase by 15 steps, and after a delay of 5 s after adjustment, the ns range is determined again. If ns≤2190 r / min is collected for more than 1 s, the electronic controller automatically issues an instruction to control the step motor step number to increase by 15 steps again, and so on. The maximum increase in step motor step number is not more than 150 steps.

[0014] Preferably, when the engine speed ng≥86%, the speed selection step instruction CLA is automatically selected as X1 (the calibration value), and after a delay of 5 s, the propeller speed ns is determined to be between [2000±10] r / min. If the propeller speed ns is collected for more than 1 s within the range of [2000±10] r / min, the electronic controller automatically issues an instruction to control the step motor step number to decrease by 15 steps. After adjustment, the ns range is determined again after a delay of 5 s. If ns is collected for more than 1 s within the range of [2000±10] r / min, the electronic controller automatically issues an instruction to control the step motor step number to decrease by 15 steps again, and so on. The maximum decrease in step motor step number is not more than 150 steps.

[0015] Preferably, when the engine speed ng≥86%, the speed selection step instruction CLA is automatically selected as X1 (the calibration value), and after a delay of 5 s, the propeller speed ns is determined to be between [2000±10] r / min. If the propeller speed ns is collected for more than 1 s within the range of [2000±10] r / min, the electronic controller automatically issues an instruction to control the step motor step number to decrease by 15 steps. After adjustment, the ns range is determined again after a delay of 5 s. If ns is collected for more than 1 s within the range of [2000±10] r / min, the electronic controller automatically issues an instruction to control the step motor step number to decrease by 15 steps again, and so on. The maximum decrease in step motor step number is not more than 150 steps.

[0016] Preferably, when the engine speed 94%≤ng≤96%, the speed selection step instruction CLA is maintained in the last state after compensation.

[0017] Beneficial effects: the existing large unmanned aerial vehicle with small and medium-sized turboprop engine propeller speed regulator generally uses a stepping motor as a speed selection execution mechanism. The engine electronic controller controls the stepping motor by counting steps in an open-loop manner. Different propeller speeds require different stepping positions, which need to be calibrated in relation to the propeller speed and the stepping position according to a specific calibration program during engine ground test. When the engine electronic controller controls the stepping motor to select the propeller speed, it first looks up the corresponding calibration steps for different speeds by using the interpolation method, and the steps corresponding to different speeds have different default values. The controller then controls the stepping motor to run the corresponding steps to select the required propeller speed. However, due to the inherent step loss of the stepping motor, there is a random step loss (loss of steps) during operation. The number of steps lost each time is different, and the deviation in speed is also different. In addition, during the same flight process, the longer the running time, the greater the cumulative deviation caused by step loss, resulting in the deviation of the propeller from its required optimal balance working speed. Due to the structural form of the propeller speed regulator, it is not possible to collect the position feedback signal of the stepping motor running position by increasing the displacement sensor to perform position closed-loop control to correct the deviation caused by step loss. In the manned mode, the pilot usually adjusts the actual speed of the propeller manually to ensure that the propeller works at the required optimal speed. In the unmanned mode, the pilot needs to pay attention to more flight task system information than in the manned mode, and requires the engine and propeller to have full autonomous control capability to automatically select the speed and reduce the pilot's burden. Therefore, the present application proposes a propeller speed drift automatic compensation law to solve the problem of propeller balance speed drift caused by step loss of the stepping motor speed selection. In addition, due to the existence of mechanical manufacturing tolerances and factory debugging test tolerances of the propeller speed regulator, different propeller speed regulators have different actual step number instructions corresponding to the same propeller speed, which requires repeated engine ground test running calibration program to find the relationship between the propeller speed and the stepping motor step number, and write the actual step number and speed corresponding relationship into the controller program. The calibration process is complicated and there is a waste of human and material resources. Therefore, the present application also proposes an online calibration method for the relationship between the propeller speed and the step number. This method does not require a special ground test program, and can be combined with other engine ground tests. The calibration can be completed through simple online operation. Through the above two methods, the two main problems of the stepping motor speed selection structure of the propeller speed regulator of the small and medium-sized turboprop engine for unmanned aerial vehicles are solved, and the precise control of the propeller speed in the unmanned mode is realized. DETAILED DESCRIPTION

[0018] Take a certain type of turboprop engine as an example, the propeller best flight working speed is divided into 1700r / min, 1800r / min, 1900r / min three balance speed, the corresponding engine speed range is [80%, 90%], [90%, 96%], [96%, 100%], the default step value is 540 steps, 760 steps, 960 steps.

[0019] a) propeller speed online calibration method:

[0020] 1) The engine is in the state of ground running test, the unmanned aerial vehicle operator pushes the power lever to check the engine working condition, when the engine speed ng is in the interval [80%, 90%], the propeller speed should be in the interval [1700±10]r / min, if it does not meet the requirements, the operator issues "select speed motor step increase" instruction once, then the default calibration position 540 steps corresponding to the [1700±10]r / min speed is increased by 5 steps, still not meet the requirements, continue to issue "select speed motor step increase" instruction once, at this time the propeller speed is stable in the interval [1700±10]. At this time, the unmanned aerial vehicle operator issues "1700r / min calibration" communication instruction, then the current select speed stepper motor actual running step number 550 steps replaces the default 540 steps and stores into the electronic controller, the subsequent running uses 550 as the step number default value corresponding to 1700r / min speed.

[0021] 2) When the engine speed is in [90%, 96%], the propeller speed should be in [1800±10]r / min, if it is lower than this range, the operator issues "select speed motor step increase" instruction once, then the default calibration position 760 steps corresponding to the [1800±10]r / min speed is increased by 5 steps, at this time the propeller speed is stable in the interval [2190, 2210] to meet the requirements. At this time, the unmanned aerial vehicle operator issues "1800r / min calibration" communication instruction, then the current select speed stepper motor actual running step number 765 replaces the default 760 steps and stores into the controller, the subsequent running uses 765 as the step number default value corresponding to 1800r / min speed.

[0022] 3) When the engine speed ng is in the range of [96%, 100%], the propeller speed should be in the range of [1900±10] r / min. If the propeller speed is higher than this range, the operator issues a "select speed motor step reduction" instruction once, and the step number of the selected speed stepping motor is reduced by 5 steps based on the default calibration position 960 steps corresponding to the [1900±10] r / min speed, so that the propeller speed is stabilized in the range of [1900±10] r / min. At this time, the operator issues a "1900 r / min calibration" communication instruction, and the current selected speed stepping motor actual running step number 955 replaces the default 960 steps and is stored in the controller, and 955 is used as the default value of the step number corresponding to the 1800 r / min speed in the subsequent operation.

[0023] b) Propeller speed automatic compensation law:

[0024] 1) During flight, when the engine speed ng is greater than or equal to 96%, the selected speed stepping instruction CLA automatically selects 955 steps (calibration value), and when the power lever instruction PLA changes at a rate of less than or equal to ±4° / s, the propeller speed ns should be in the range of [1900±10] r / min after a delay of 5s. If the propeller speed ns is maintained in the range of [1900, 1944] for more than 1s, the electronic controller automatically issues an instruction to control the stepping motor step number to reduce by 15 steps. After adjustment, the ns range is determined again after a delay of 5s, and if ns is maintained in the range of [1900, 1940] for more than 1s, the electronic controller automatically issues an instruction to control the stepping motor step number to reduce by 15 steps again, and so on. The maximum reduction of the stepping motor step number is not more than 105 steps;

[0025] 2) If ns is maintained in the range of [1940, 1980] for more than 1s, the electronic controller automatically issues an instruction to control the stepping motor step number to reduce by 30 steps, and the maximum reduction is not more than 105 steps according to the above steps;

[0026] 3) When the engine speed ng is in the range of [90%, 96%], the selected speed stepping instruction CLA automatically selects 955 steps (calibration value), and when the power lever PLA instruction changes at a rate of less than or equal to ±4° / s, the propeller speed ns should be in the range of [1800±10] r / min after a delay of 5s. If ns is less than or equal to 1790 r / min and is maintained for more than 1s, the electronic controller automatically issues an instruction to control the stepping motor step number to increase by 15 steps, and after adjustment, the ns range is determined again after a delay of 5s. If ns is less than or equal to 1790 r / min and is maintained for more than 1s, the electronic controller automatically issues an instruction to control the stepping motor step number to increase by 15 steps again, and so on until the speed meets the requirement of [1800±10] r / min. The maximum increase of the stepping motor step number is not more than 150 steps;

[0027] 4) When the engine speed ng is between [80%, 90%], the speed selection step instruction CLA is automatically selected as 550 steps, and after a delay of 5s, it is determined that the propeller speed ns should be between [1700±10] r / min. If the collected propeller speed ns≥1710 r / min is maintained for more than 1s, the electronic controller automatically issues an instruction to control the step motor step number to decrease by 15 steps. After adjustment, the ns range is determined again after a delay of 5s, and if the collected ns≥1710 r / min is maintained for more than 1s, the electronic controller automatically issues an instruction to control the step motor step number to decrease by 15 steps again, and so on, until the speed meets the requirement of [1700±10] r / min, and the maximum decrease in step motor step number is not more than 150 steps;

[0028] 5) When the engine speed ng is between [80%, 90%], the speed selection step instruction CLA is selected as 550 steps (the calibration value), and after a delay of 5s, it is determined that ns should be between [1700±10] r / min, and if the collected ns≤1690 r / min is maintained for more than 1s, the electronic controller automatically issues an instruction to control the step motor step number to increase by 15 steps, and after adjustment, the ns range is determined again after a delay of 5s, and if the collected ns≤1690 r / min is maintained for more than 1s, the electronic controller automatically issues an instruction to control the step motor step number to increase by 15 steps again, and so on, and the maximum increase in step motor step number is not more than 100 steps.

[0029] 6) The electronic controller is powered on again, the current operation is ended, and the speed selection step instruction step number returns to the calibration state.

[0030] The method described in the application has developed products, which have been tested individually and actually used on a certain type of turboprop engine, and have undergone ground tests and flight tests with the turboprop engine. The test and use results have shown that the method is reasonable, feasible, and highly reliable, has promotional significance, and can ensure accurate speed selection control of the propeller of the same type of turboprop engine within the full envelope range.

Claims

1. A method for controlling the rotational speed of the propeller of a turboprop engine for a drone, characterized in that, It comprises the following steps: In the ground running test state, the propeller speed of the unmanned aerial vehicle turboprop engine is calibrated to obtain the actual running step number of the selected speed stepping motor corresponding to the required different propeller speeds, which is stored in the electronic controller as the default step number; During flight, the selected speed stepping instruction CLA automatically selects the default step number, and if the monitored actual speed does not meet the requirements, the propeller speed is controlled by using the automatic compensation law, and the specific steps include: if the propeller speed is greater than the default step number, the electronic controller automatically issues an instruction to control the step number of the stepping motor to decrease by a certain number; if the propeller speed still does not meet the requirements, the electronic controller automatically issues an instruction to control the step number of the stepping motor to decrease by a certain number again, and so on until the stable range of the propeller speed meets the requirements; if the propeller speed is less than the default step number, the electronic controller automatically issues an instruction to control the step number of the stepping motor to increase by a certain number; if the propeller speed still does not meet the requirements, the electronic controller automatically issues an instruction to control the step number of the stepping motor to increase by a certain number again, and so on until the stable range of the propeller speed meets the requirements; The electronic controller is powered on again, and the current operation ends, and the step number of the selected speed stepping instruction returns to the calibration state; In the ground running test state, the propeller speed of the unmanned aerial vehicle turboprop engine is calibrated to obtain the actual running step number of the selected speed stepping motor, which is stored in the electronic controller as the default step number, and the specific steps include: The engine is in the ground running test state, and the unmanned aerial vehicle operator pushes the power lever to check the engine operation. If the actual propeller speed is lower than the set speed range, it does not meet the requirements. The operator issues a "selected speed stepping motor step number increase" instruction once through communication, which increases the running step number of the selected speed stepping motor at the default calibration position corresponding to the set speed range by a certain number. At this time, the propeller speed will increase, and if it still does not meet the requirements, the operator will continue to issue a "selected speed stepping motor step number increase" instruction, and the speed will continue to increase until the propeller speed stabilizes within the set speed range. At this time, the unmanned aerial vehicle operator issues a write communication instruction to replace the default selected speed stepping motor running step number with the current selected speed stepping motor actual running step number and store it in the electronic controller. The updated current selected speed stepping motor actual running step number is used as the default value in subsequent operation.

2. The method according to claim 1, wherein In the ground running test state, the propeller speed of the unmanned aerial vehicle turboprop engine is calibrated to obtain the actual running step number of the selected speed stepping motor, which is stored in the electronic controller as the default step number, and the specific steps include: When the engine speed ng is greater than or equal to 86% and less than 96%, the propeller speed should be between [2000±10] r / min. If the actual propeller speed is lower than this range, the requirement is not met. The operator issues the "select speed step motor step number increase" instruction once through communication, and the current selected speed step motor actual running step number X1 replaces the default 720 steps and is stored in the electronic controller. In subsequent operation, the updated X1 step number is used as the default value.

3. The method according to claim 1, wherein When the engine speed ng is greater than or equal to 86% and less than 96%, the propeller speed should be between [2000±10] r / min. If the actual propeller speed is lower than this range, the requirement is not met. The operator issues the "select speed step motor step number increase" instruction once through communication, and the current selected speed step motor actual running step number X1 replaces the default 720 steps and is stored in the electronic controller. In subsequent operation, the updated X1 step number is used as the default value. The propeller speed automatic compensation law includes: during flight, when the engine speed ng is greater than or equal to 96%, the selected speed step instruction CLA automatically selects the step number default value, when the power lever instruction PLA change rate is less than or equal to ±4° / s, after a delay of 5s, it is determined that the propeller speed ns should be between [2200±10] r / min; if the collected propeller speed ns is greater than this range, and the time within the range of [2210, 2244] r / min is more than 1s, the electronic controller automatically issues an instruction to control the step motor step number to decrease by 15 steps; after adjustment, after a delay of 5s, the propeller speed ns range is determined again, if the collected propeller speed ns is within the range of [2210, 2244] r / min and the time is still more than 1s, the electronic controller automatically issues an instruction to control the step motor step number to decrease by 15 steps again, and so on, until the speed stable range meets the requirement of [2200±10] r / min, and the step motor step number automatically decreases by a maximum of 105 steps.

4. The method of claim 1, wherein the method is used for a turboprop engine of a drone. ​ If the propeller speed ns is maintained in [2244, 2288] for more than 1s, the electronic controller automatically sends a command to control the step motor to reduce the step number by 30 steps, and so on until the speed stabilizes in the range of [2200±10] r / min, and the maximum automatic reduction of the step motor is not more than 105 steps.

5. The method of claim 1, wherein the method is used for a turboprop engine of a drone. The propeller speed automatic compensation law includes: during flight, when the engine speed ng≥96%, the selected speed step instruction CLA automatically selects the default value of the step number, and when the power lever PLA instruction change rate is ≤±4° / s, the propeller speed ns should be between [2200±10] r / min after a delay of 5s; if the propeller speed ns≤2190 r / min is maintained for more than 1s, the electronic controller automatically sends a command to control the step motor to increase the step number by 15 steps, and after the adjustment is completed, the propeller speed ns range is determined again after a delay of 5s; if the propeller speed ns≤2190 r / min is still maintained for more than 1s, the electronic controller automatically sends a command to control the step motor to increase the step number by 15 steps again, and so on, and the maximum increase of the step motor is not more than 150 steps.

6. The method of claim 1, wherein the method is used for a turboprop engine of a drone. The propeller speed automatic compensation law includes: during flight, when the engine speed ng≥86%, the selected speed step instruction CLA selects the default value of the step number, and after a delay of 5s, the propeller speed ns should be between [2000±10] r / min; if the propeller speed ns≤1990 r / min is maintained for more than 1s, the electronic controller automatically sends a command to control the step motor to increase the step number by 15 steps, and after the adjustment is completed, the propeller speed ns range is determined again after a delay of 5s; if the propeller speed ns≤1990 r / min is still maintained for more than 1s, the electronic controller automatically sends a command to control the step motor to increase the step number by 15 steps again, and so on, and the maximum increase of the step motor is not more than 100 steps.

7. The method of claim 1, wherein the method is used for a turboprop engine of a drone. The propeller speed automatic compensation law includes: during flight, when the engine speed 94%≤ng≤96%, the selected speed step instruction CLA maintains the last state after compensation.