CN105134392B - Small-sized depopulated helicopter petrol engine revolution speed control system and its control method - Google Patents

Abstract

The invention discloses a small unmanned helicopter gasoline engine speed control system, which includes a speed measurement module, a core controller module, a control signal execution module, and a power management module; the speed measurement module includes a speed signal acquisition module, a speed calculation module, Data processing module; the present invention also discloses a control method of a small-sized unmanned helicopter gasoline engine speed control system, including the following steps: 1. A high-voltage pulse signal is generated every time the engine rotates, and the high-voltage pulse signal passes through the speed signal acquisition module The external capture interface of the timer is connected to the speed calculation module; 2. Use the T method to calculate the engine speed value; 3. Analyze the fused speed data and GPS module data respectively; 4. The speed control algorithm calculates the set The difference between the rotational speed value and the measured rotational speed value; 5. Change the rotational speed of the engine. It has the advantages of good scalability and wide compatibility.

Description

Small unmanned helicopter gasoline engine speed control system and its control method

technical field

The invention relates to a technology for controlling the engine speed by using the principle of automatic control, in particular to a small unmanned helicopter gasoline engine speed control system and its control method. The invention is suitable for the speed control of the small unmanned helicopter gasoline engine. Electronic systems such as speed measurement, data communication, and control signal output.

Background technique

Most of the small (micro) unmanned helicopters currently in use are driven by electric power. This is because the structure of the electric drone is relatively simple, the controller design is highly operable, and the interference of the electric motor to the communication system is relatively small. Due to the limited power of its power system, this type of helicopter is often unable to provide a large payload, and its stagnation time and effective range are greatly limited. Therefore, when performing long-distance, long-duration, and heavy-load flight missions, unmanned helicopters driven by gasoline engines have become a suitable choice. The gasoline engine can not only provide more powerful power, but also ensure the stability of the rotor speed of the helicopter under severe weather conditions, eliminating the battery maintenance work of the electric engine and improving the efficiency of the aircraft.

The realization of UAV functions depends on a reliable flight control system. However, the gasoline engine introduces a series of electromagnetic interference, which affects the reliability of the flight control system. Gasoline engine speed stability is poor, which will lead to poor flight stability of unmanned helicopters. During the flight of the helicopter, changes in the load, changes in weather conditions, and the maneuvering of the aircraft itself will change the load on the gasoline engine, which will affect the speed of the gasoline engine. At this time, a certain control signal must be applied to stabilize the speed of the gasoline engine in order to stabilize the flight state of the helicopter. At present, domestic and foreign research results on unmanned gasoline engines are limited, and there are relatively few control systems for gasoline engines on unmanned helicopters. It can be seen that in order to minimize the impact of gasoline engines on helicopter control, it is necessary to design a gasoline engine. The independent controller enables it to provide stable power output for the helicopter. The small unmanned helicopter gasoline engine speed control system of the present invention is suitable for small unmanned helicopters with a load of 20 kilograms, and has strong compatibility, high expandability, stability and reliability.

Contents of the invention

The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and propose a small unmanned helicopter gasoline engine speed control system, which is a small unmanned helicopter with high stability, strong scalability and easy implementation Gasoline engine speed control system.

Another object of the present invention is to provide a control method for controlling the speed control system of a gasoline engine of a small unmanned helicopter.

Primary purpose of the present invention adopts following technical scheme to realize:

A small unmanned helicopter gasoline engine speed control system, including a speed measurement module, a core controller module, a control signal execution module and a power management module; the speed measurement module includes a speed signal acquisition module, a speed calculation module, and a data processing module; The control signal execution module includes a 4017 frequency divider and a servo servo module;

The speed signal acquisition module is connected to the AVR processor chip of the speed calculation module through the external signal input capture interface of the speed calculation module, and the speed calculation module communicates with the core controller module through the URAT communication protocol. During the process, the data processing module is required to perform data filtering and fusion processing, the core controller module outputs 5v PWM signals to the control signal execution module, and the power management module provides stable power support for all modules;

The rotational speed signal acquisition module converts the rotational speed information of the engine into a pulse signal, and accesses the AVR processor of the rotational speed calculation module through the input capture interface of the timer T1. The rotational speed calculation module recognizes the pulse signal and calculates the corresponding rotational speed value. The rotational speed value needs After the filtering process of the data processing module, and then according to the unique method of fusion with the GPS module data, it is sent to the DEBUG interface of the core controller module through the serial port, and the data is analyzed by the core controller module to obtain the GPS module data, speed data, and speed data respectively. As feedback information to the speed control algorithm on the core controller, the speed control algorithm compares the speed data with the given value data to calculate the PWM value of the control signal, and outputs the control signal to the servo steering gear after being processed by the 4017 frequency divider , and then control the engine speed.

Preferably, the pulse sensor of the rotational speed signal acquisition module has hardware filtering and the ability to resist external high-frequency electromagnetic interference.

Preferably, the transmission method of the rotational speed signal, the power amplification processing circuit designed before being connected to the AVR processor, the identification method of the rotational speed signal in the AVR processor and the method of calculating the rotational speed data.

Preferably, the processing method of the initial speed data, the data format of the fusion of the speed data and the GPS module data, the data transmission method, transmission speed, and the analysis method of the data on the core processor.

Preferably, the core controller module includes an ARM processor module, an interface conversion module, an air pressure sensor module, a three-axis gyroscope module, and an I/O interface module.

Preferably, the power management module is composed of two switching power supply chips with an output capacity of 3A, which provides two voltages of 5V and 3.3V for the entire engine control system, and has the functions of level conversion, stable voltage output, and short-circuit isolation.

Another object of the present invention is achieved through the following technical solutions:

A control method for controlling the gasoline engine speed control system of the small unmanned helicopter, comprising the following steps:

Step 1. The gasoline engine generates a high-voltage pulse signal every time it rotates. The speed signal acquisition module collects the pulse signal. The sensor hardware in the signal acquisition module integrates a filter to filter out the noise of the pulse signal to obtain an ideal The pulse signal is amplified by the amplifier, and connected to the speed calculation module through the external capture interface of the timer T1 of the AVR processor.

Step 2. The AVR processor in the speed calculation module recognizes the speed pulse signal, and uses the timer T1 as a time mark when capturing the signal, and then uses the T method to calculate the speed value; the initial speed value will be abnormal due to high-frequency noise interference. For periodic jumps, use median value window filtering to process the initial speed value; in the entire flight control system, the speed calculation module is also responsible for receiving and forwarding the GPS module data, and the speed data needs to be fused with the GPS module data and sent to the core controller module;

Step 3. After the core controller module receives the fused data, it analyzes the GPS module data and the speed data respectively through the analysis algorithm. The GPS module data is used for the calculation of the flight state of the helicopter, and the speed data is used for the calculation of the control signal;

Step 4, the speed controller adopts a classic PID control algorithm, the PID control algorithm is implemented in the core controller module in the form of software, and the control signal is obtained by calculating the difference between the given speed value and the measured speed value, In order to achieve the effect of finally eliminating the difference;

Step 5, the speed control algorithm in the core controller module calculates the control signal, and outputs it to the 4017 frequency divider module in the control signal execution module in the form of PWM value, and through the processing of the frequency divider, from the fifth The channel is output to the servo steering gear, and the servo steering gear makes corresponding actions according to the control signal to drive the throttle valve of the engine, and the opening of the throttle valve changes accordingly, changing the speed of the engine.

Preferably, in step 2, the T method to measure the rotational speed is a method of calculating the rotational speed value by measuring the time interval between two adjacent pulses. The higher the crystal oscillator frequency of the AVR processor, the more accurate the data obtained by this method ; According to the timer count value T _c in Fig. 1, the time between two pulses can be further obtained according to the clock frequency f _t , thereby calculating the rotating speed (unit rpm), the calculation formula of the rotating speed is

Using an 8Mhz crystal oscillator can meet the speed measurement requirements of gasoline engines; the median value window filter can effectively filter out invalid values in the speed measurement, and the filter method with a window length of 6 can ensure the filtering effect and avoid excessive delay. Time.

Preferably, in step 3, the rotational speed measurement module and the core controller module establish communication according to the UART protocol, and the analysis of the data is solved by matching data messages, and each type of data corresponds to a unique message, and the message comparison If successful, update the array where the data is located; the format of each group of data packets is:

$GPGGA,data,$GPVTG,data,$HMC,data,$SPEED,data.

The data packet is divided into four parts, and each part has a header to identify the type of the data segment. The first two parts are GPS sensor data, the third part is compass data, and the last part is engine speed data. After the data is received by the ARM processor in the core controller module, the GPS module, compass and engine speed data can be obtained after data analysis.

Preferably, in step 4, the control algorithm adopted by the core controller module is a PID control algorithm, a standard PID control algorithm such as formula:

The measured value of the output y(t) will be affected by the noise of the sensor, and the system will be affected by the external disturbance d(t), the error signal e(t) is given by the input y _ref (t) and the output value y(t) The control signal u(t) is obtained by calculating e(t) through the calculation of the proportional link, the integral link and the differential link, and then summing it up.

The principle of the present invention: the present invention includes the reading method of the engine speed signal, the calculation method of the engine speed, the integrated transmission of the speed data, the design of the speed controller, and the calculation output of the control signal. By designing the software and hardware parts of the relevant electronic system, improving The composition of the existing flight control system realizes the function of speed control, and integrates the system into the currently used flight control system to realize the constant speed control of the engine. The engine speed control system of the present invention not only realizes the constant speed function of the engine, optimizes the flight stability of the helicopter when the gasoline engine is driven, but also expands the range of the constant speed, and can dynamically adjust the constant speed value, and has good scalability and broad compatibility

Compared with the prior art, the present invention has the following advantages and effects:

1. The invention constructs a small unmanned helicopter gasoline engine speed control system, realizes the speed control function of the helicopter gasoline engine, enhances the flight stability of the helicopter, and has the advantages of good real-time performance, high integration, low cost, and high reliability. .

2. The present invention independently designs the software and hardware system of the speed control system, the model identification method of the engine, the optimization method of the engine controller parameters, and the data communication method. Provides a set of specific methods for designing gasoline engine speed control system.

3. The present invention overcomes the shortcomings of the original system that the range of fixed speed is small and the constant speed value cannot be adjusted in real time, and realizes the constant speed control of the gasoline engine in a relatively large range, and can adjust the constant speed value in real time.

4. The electronic system of the present invention is designed based on the flight control system, which is perfectly compatible with the entire flight control system, improves the integration of the system, and saves development costs.

5. The invention makes up for the shortcomings of the flight control system of small unmanned helicopters, has good scalability, and lays a foundation for the research of advanced control methods for gasoline engine speed control.

Description of drawings

Fig. 1 is the schematic diagram of T method measuring rotational speed among the present invention.

Fig. 2 is a system structure diagram of the present invention.

Fig. 3 is a schematic diagram of the speed measuring system used in this embodiment.

Fig. 4 is a flow chart of the program using the speed measurement software in this embodiment.

Fig. 5 is a program flow chart of the controller software in this embodiment.

Fig. 6 is a schematic diagram of the power management module in this embodiment.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example

As shown in Figure 2, the small unmanned helicopter gasoline engine speed control system of the present embodiment includes three parts as a whole: a speed measurement unit, a core controller and an auxiliary circuit unit, and a control signal execution unit, wherein the speed measurement unit includes a speed signal acquisition unit module, signal amplification circuit and speed calculation module, the core controller and auxiliary circuit are composed of the main processor, interface conversion circuit, related attitude and height sensor module, power management module, the control signal execution unit includes 4017 frequency division circuit, servo steering gear . The speed control system composed of these three parts is attached to the main flight control system in terms of hardware, and is independent of the main flight control system in terms of function realization, which does not affect the realization of the performance of the flight control system.

As shown in Figure 3, the rotational speed calculation module of this embodiment selects the ATMEGA8L processor produced by ATMEL Company, which is based on the classic RISC architecture and integrates non-volatile data memory. There are two programmable serial UART ports, and a 16-bit timer/counter with prescaler, comparison function and capture function, which can fully meet the needs of system design. The AVR processor mainly completes the tasks of GPS module data reading, rotational speed data calculation and data transmission. Among them, the AVR is connected with the GPS module and the core controller through the universal serial port UART, and the baud rate is 19200; the identification of the rotational speed sensor signal, The speed sensor outputs a pulse signal with an amplitude of 5V, but there will be a certain degree of attenuation through the transmission of the signal line, so it needs to be amplified before being sent to the AVR. The amplified signal is captured by the AVR and used to calculate the speed.

This embodiment uses the input capture mode of the 16-bit timer/counter T1 of AVR to capture the speed signal. The timer T/C has an input capture unit. After the external event is captured by this unit, the corresponding occurrence time can be obtained, accounting for Signal characteristics such as empty ratio and frequency can be calculated by using these time markers, and the trigger signal of external events is input by pin ICP1. Use this unit to capture the pulse signal of the speed sensor. Whenever a pulse arrives, the timer stops counting, returns the count value TCNT1 and clears it to zero. According to the count value, the pulse frequency can be calculated by using the formula, and then the engine speed can be calculated. . The AVR uses an 8Mhz external clock, which can fully meet the measurement of the speed above 10000rpm. Figure 4 shows the program flow chart of speed measurement. It should be noted that when the speed is very low, the interval between two pulses is long, which may exceed the maximum count value of T1 65535. At this time, the timer will reverse rotation, the rotation speed value calculated by the above method will become meaningless. After calculation, when the T1 count value is 65535, the corresponding speed value is 915rpm, which is not only far lower than the engine operating speed, but also lower than the minimum speed for engine startup, so this problem has no effect on the work of the speed measurement system, but in order to ensure the system For reliability, it is necessary to deal with the timer overflow situation.

Present embodiment adopts ARM7 microprocessor as the processor of core controller, and this processor is the AT91SAM7SE (512) processor of ATMEL company, has UART interface, TWI interface and SPI interface based on ARM7TDMI kernel design, can fully realize sensor data Receive and process, and be able to complete the operation of the control algorithm program. The speed controller is a PID controller, which runs on the ARM7 processor in the form of software. The updated speed data is compared with the set value of the speed to make a difference. The difference is calculated by the proportional link, the integral link, and the differential link. , and then summed to get the control signal, the purpose of the control signal is to gradually reduce the difference between the actual engine speed and the target speed, so that the engine speed is finally maintained at the target speed and remains constant.

As shown in Figure 5, the power management module of this example uses the TPS5430 switching power supply chip, which supports an input signal of 5.5-36V and can provide a stable output current of 3A, which can fully meet the needs of the new system.

The control signal execution module of this example is used by the frequency divider and the servo steering gear. The frequency divider adopts a CD4017 pulse distributor, which can divide the PWM pulse signal into 10 channels, which can fully meet the control signal output requirements of the flight control system with 8 channels. The control signal of the engine is assigned to output on the fifth channel. The servo steering gear uses the S9206 analog steering gear produced by Futaba. The servo steering gear converts the control signal from an electrical signal into a torque signal, and drives the engine throttle to move, thereby achieving control The purpose of its speed.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. A small-sized unmanned helicopter gasoline engine speed control system is characterized in that, comprising: a speed measurement module, a core controller module, a control signal execution module, a power management module; the speed measurement module includes a speed signal acquisition module, a speed Calculation module, data processing module; the control signal execution module includes: 4017 frequency divider, servo steering gear module; The speed signal acquisition module is connected to the AVR processor chip of the speed calculation module through the external signal input capture interface of the AVR. The speed calculation module communicates with the core controller module through the URAT communication protocol. During the communication process between the speed calculation module and the core controller module , the data processing module is required for data filtering and fusion processing, the core controller module outputs 5v PWM signals to the control signal execution module, and the power management module provides stable power support for all modules; The rotational speed signal acquisition module converts the rotational speed information of the engine into a pulse signal, and accesses the AVR processor of the rotational speed calculation module through the input capture interface of the timer T1. The rotational speed calculation module recognizes the pulse signal and calculates the corresponding rotational speed value. The rotational speed value needs After the filtering process of the data processing module, it is fused with the data of the GPS module, and sent to the DEBUG interface of the core controller module through the serial port. To the speed controller on the core controller, the speed controller compares the speed information with the given value information to calculate the PWM value of the control signal, and outputs the control signal to the control signal execution module after processing by the 4017 frequency divider. The control signal execution module controls the rotational speed of the engine. 2. the small unmanned helicopter gasoline engine speed control system according to claim 1, is characterized in that, described speed measurement module is connected with GPS module, and described speed measurement module is used for collecting the pulse signal that engine rotates, calculates and processes For the corresponding rotational speed data, the said rotational speed data is fused with the data of the GPS module and encoded and sent. 3. the small-sized unmanned helicopter gasoline engine speed control system according to claim 1, is characterized in that, the communication mode of described core controller module comprises the communication mode of AVR processor and the communication mode of GPS module, the communication mode of signal acquisition module respectively The communication method with the core controller, and the processing method when the communication between the AVR processor and the GPS module, the communication between the AVR processor and the signal acquisition module, and the communication between the AVR processor and the core controller are concurrent. 4. the small-sized unmanned helicopter gasoline engine speed control system according to claim 1, is characterized in that, the data format of described core controller module comprises to the integrity of data transmission/reception, data type, data content, data transmission speed Define and form a standard format, so that the data can be generated, analyzed and processed between the rotational speed measurement module and the core controller module. 5. small unmanned helicopter gasoline engine speed control system according to claim 1, is characterized in that, described core controller module comprises ARM processor module, interface conversion module, air pressure sensor module, three-axis gyroscope sensor module , I/O interface module. 6. The small unmanned helicopter gasoline engine speed control system according to claim 1, wherein the control signal execution module includes a PWM signal frequency division unit and a servo steering gear unit, and the control signal execution module will The control signal output by the core controller module is output to the engine throttle, and the engine throttle controls the rotational speed of the engine. 7. The small unmanned helicopter gasoline engine speed control system according to claim 1, wherein the power management module is used to provide power for the small unmanned helicopter gasoline engine speed control system. 8. A control method for controlling the small-sized unmanned helicopter gasoline engine speed control system according to claim 1, is characterized in that, comprises the following steps: Step 1, the control object of the gasoline engine speed control system of the small unmanned helicopter is the engine, and the engine will generate a high-voltage pulse signal every time it rotates, and the speed signal acquisition module collects the high-voltage pulse signal. The rotation speed signal acquisition module is integrated with a filter to filter out the noise of the high-voltage pulse signal. The high-voltage pulse signal is amplified by the operational amplifier in the rotation speed signal acquisition module. The external capture interface of the timer in the module is connected to the speed calculation module; Step 2, the AVR processor in the said rotational speed calculation module recognizes the rotational speed pulse signal of the said engine, and uses the timer to do the time stamp when capturing the signal, then calculates the rotational speed value of the engine with the T method; use the median value window Filter and process the initial speed value; in the entire flight control system, the speed calculation module receives and forwards the data of the GPS sensor, and the speed data of the engine is fused with the data of the GPS module and sent to the core controller module through the speed calculation module; Step 3, the core controller module receives the fused speed data and the data of the GPS module, and analyzes the fused speed data and the data of the GPS module respectively through an analysis algorithm, and the data of the GPS module is used to calculate the helicopter In flight state, the rotational speed data is used to calculate the value of the engine rotational speed control signal; Step 4, the speed control algorithm of the core controller module adopts a PID controller, the speed control algorithm is realized by the code in the core controller module, and the speed control algorithm calculates the set speed value and the measured speed value the difference between Step 5, the speed control program of the core controller module calculates the control signal of the engine speed, and outputs it to the control signal execution module in the form of PWM value, and the control signal execution module drives the engine throttle to move, so that the engine throttle The switch produces a corresponding change, changing the speed of the engine. 9. The control method according to claim 8, wherein said step 2 further comprises the following steps: Step 21, said T method for measuring the rotational speed is a method of calculating the engine rotational speed value by measuring the time interval between two adjacent pulses; Step 22, median value window filtering can effectively filter out invalid values in the engine speed data, and the window length of the median value window filtering is 6; Step 23, the GPS module data is received to the rotational speed measurement module through the serial port UART according to the baud rate of 19200, the GPS module data is transmitted according to the fixed format of the data message and the data segment, after the rotational speed data GPS module data fusion, the rotational speed measurement module The UART port of the UART port is sent to the core controller module, and the transmission baud rate is 19200. 10. The control method according to claim 8, wherein said step 3 further comprises the following steps: Step 31, the speed measurement module and the core controller module establish communication according to the UART protocol, and the analysis of the speed data and the GPS module data is realized by matching data messages, and the speed data and the GPS module data correspond to unique messages respectively, and the report If the text matching is successful, the corresponding data will be updated; Step 32. The speed data of the core controller module is updated at a frequency of 30 Hz. The updated speed data is directly used to calculate the value of the engine control signal. If the update fails, the speed data before the update is used.