RU106971U1 - AUTOMOTIVE CONTROL SYSTEM FOR UNMANNED AIRCRAFT - Google Patents

Abstract

An automatic control system for an unmanned aerial vehicle, containing roll and heading rate sensors, differential and total pressure sensors, analog-to-digital converters, a computer for software processing of signals from sensors and generation of control signals, units for generating control signals for actuators, actuators, and also a receiver of a satellite navigation system, characterized in that to calculate the angular position of an unmanned aerial vehicle (UAV), it uses only two angular rate sensors and total and differential pressure sensors, the outputs of which are connected to the inputs of the corresponding analog-to-digital converters, which in turn are connected to the computer, which contains software blocks that allow you to correct the signals from the angular rate sensors (ARS) and provide an estimate of the angular position of the aircraft (AC) without using satellite navigation signals system (SNS), while the computer contains software modules containing subtractors, proportional and isodromic links connected to the PWM signal generation units and actuators that allow control of the UAV in the roll, course and pitch channels, and the system is equipped with a satellite navigation receiver. system and a nonvolatile memory module for entering information about the geographic coordinates of the aircraft location into the system.

Description

The utility model relates to automatic control systems for unmanned aerial vehicles (UAVs) with static longitudinal and lateral stability, allowing to stabilize the angles of the aircraft, heading, speed, altitude, rate of climb, to fly along a given path with reference to geographical coordinates, to take off automatically and landing of the aircraft and is designed to stabilize the aircraft in flight and to control its lateral and longitudinal movement iem.

A known automatic control system for an unmanned aerial vehicle, which contains a block of accelerometers for measuring linear accelerations of an object in a projection on the axis of a connected coordinate system, a block of angular velocity sensors for measuring angular velocities of an object in a projection on a axis of a connected coordinate system, a block of magnetic sensors for measuring a magnetic field vector Earth in projection on the axis of the associated coordinate system, temperature sensors for measuring the temperature of angular velocity sensors, accelerometers, magnesium tnny sensors, temperature of outside air; absolute pressure sensor and differential pressure sensor, unit for estimating altitude, airspeed and rate of climb, satellite navigation receiver for entering into the system information about the geographical coordinates of the aircraft’s location, units for measuring the external engine speed of the aircraft, as well as a programmable control unit. The system is also equipped with a multi-channel analog-to-digital converter, the outputs of these sensors are connected to the input, a sensor signal correction block, which is designed to compensate for errors in sensor readings caused by temperature drifts and irregularity of the sensor axes, to the input of which the outputs of a multi-channel analog-to-digital converter are connected, unit for evaluating the angular position of the object, performed with the function of evaluating the current angles of the position of the aircraft according to the parameters , roll and pitch, and the input of which is connected to the output of the sensor signal correction block, the PWM signal capture block, configured to receive control actions to the system from an external source that defines these actions, by the flight program processing unit, which is designed to track the current state of flight parameters and making decisions on changing the control circuit of the aircraft, and associated with the input of the programmable control unit and the output of non-volatile memory, critical tracking unit situations performed with the function of generating a signal for the flight program development block, which, upon receipt of this signal, loads the flight program for execution, which guarantees the preservation of the aircraft, by the block generating PWM steering steering signals, configured to implement the function of generating PWM signals with a given frequency and duty cycle depending on the control signal coming from the programmable control unit, as well as the interface module for implementing data exchange with external devices (RF patent for utility model No. 68145, IPC G05D 1/10, 2007).

However, this system has a rather complicated scheme, including a block of magnetic sensors, which leads to restrictions on its use.

Closest to the proposed system is a system for measuring the angular positions of an aircraft containing angular velocity and linear acceleration sensors, a satellite navigation system and a digital computer. The digital computer synchronously receives data from information systems and provides real-time coordination of the trajectory generated by the signals of the angular velocity and linear acceleration sensors with the trajectory measured by the satellite navigation system (RU No. 224262, G05D 1/00, published January 10, 2005) .

The disadvantage of this system is that for the calculation of the angular positions of the aircraft requires the presence of SNA signals.

The proposed system combines the solution of the control problem and the problem of determining the position of the aircraft.

The technical result achieved in this case is to ensure the stabilization of the UAV relative to the center of mass, the formation of a trajectory with a given height of horizontal flight, as well as the implementation of a given flight profile in areas specified by turning points of the route. The system has the ability to implement various UAV control models and carry out UAV control in automatic and semi-automatic modes.

The specified technical result is achieved by the fact that the automatic control system of an unmanned aerial vehicle contains angular velocity sensors for roll and heading, differential and total pressure sensors, analog-to-digital converters, a computer for processing signals from sensors and generating control signals, control signal generation units actuators, actuators, and the receiver of the satellite navigation system, while calculating the angular position UAV it is equipped with sensors of full and differential pressure, the outputs of which are connected to the inputs of the corresponding analog-to-digital converters, which in turn are connected to a computer that contains program blocks that allow you to correct signals from the TLS and provide an estimate of the angular position of the aircraft without using SNA signals, and the calculator contains program modules containing subtractors, proportional and isodromic links connected to the PWM signal generation blocks and executive mechanisms to control the UAV in the roll, heading and pitch channels, and the system is equipped with a satellite navigation system receiver and a non-volatile memory module for introducing into the system information about the geographical coordinates of the location of the aircraft.

The system allows you to stabilize the position angles of the aircraft, heading, speed, altitude, rate of climb, to perform a flight along a given path with reference to geographical coordinates. The control system provides stabilization of the UAV relative to the center of mass, the formation of a trajectory with a given height of horizontal flight, as well as the implementation of a given flight profile in the areas specified by turning points of the route. The system has the ability to implement various UAV control models and carry out UAV control in automatic and semi-automatic modes.

Figure 1 - presents a block diagram of a system for automatic control of an unmanned aerial vehicle, which indicates:

1 - Sensor of angular velocities along the axis OX

2 - Analog-to-digital signal converter with TLS

3 - Subtractor

4 - Integrator

5 - Subtractor

6 - Switch control modes "Automatic Semi-automatic"

7 - Isodrome link roll control

8 - Block Sensor of angular velocities along the axis OY

9 - Analog-to-digital signal converter with TLS

10 - Estimated roll angle calculation unit

11 - Nonlinear link

12 - Subtracting adder

13 - The integrating link of the filter of the correction signal TLS along the axis OX

14 - Limiter

15 - Adder filter signal correction TLS along the axis OX

16 - Proportional link of the filter of the correction signal of the TLS along the axis OX

17 - Differential pressure sensor

18 - Analog-to-digital signal converter from a differential pressure sensor

19 - Airspeed Calculator

20 - Subtractor

21 - Isodromic link of the engine control loop

22 - Full pressure sensor

23 - Analog-to-digital Converter signals from a full pressure sensor

24 - Barometric altitude calculator

25 - Differentiating link of the unit for calculating airspeed

26 - Filter LF 2 orders

27 - Proportional link of the unit for calculating airspeed

28 - Subtractor

29 - Isodromic link height control loop

30 - Subtractor.

31 - Proportional link.

32 - Limiter.

33 - Non-volatile program memory.

34 - Interface module.

35 - SNA receiver (GPS, Glonass).

36 - Non-volatile route memory

37 - Navigation block

38 - Block PWM signal formation of the roll control loop

39 - Actuator - ailerons

40 - Executive engine control mechanism

41 - Block generating PWM signals of the motor control loop

42 - Block generating PWM signals of the height control loop

43 - Actuator - elevator.

Figure 2 shows the coordinate system associated with the UAV.

Micromechanical angular velocity sensors allow you to measure the angular velocity of an object along two axes of the associated coordinate system and, through their complex processing, together with signals from pressure sensors, determine the position angles of the object. Object management is performed by software-implemented control loops. There are several control loops in the system. The control signals generated by the system are PWM signals with a variable period and set limits for the duty cycle. This allows the system to be used both for controlling DC motors and for controlling power mechanisms (servos) controlled by PWM signals. The boundaries of the change in the duration of the control pulse are adjustable parameters of the PWM formers.

This utility model is illustrated by a specific example of execution, demonstrating the possibility of achieving the desired technical result.

The system (Fig. 1) consists of two angular velocity sensors (DLS) 1, 8, which measure the angular velocities of an object in the projection on the X and Y axis of the associated coordinate system (Fig. 2); full pressure sensor 22; differential pressure sensor 17. All sensor outputs are connected to the inputs of the corresponding analog-to-digital converters 2, 9, 18, 23. The signal from the remote control system along the OX 1 axis is fed to the input of the analog-to-digital converter (ADC) 2, and then to the input of the subtractor 3.

A correction signal calculated by blocks 13, 14, 15, 16 is applied to the second input of the subtractor 3. As a result, a signal proportional to the angular velocity along the OX axis of the associated coordinate system is formed at the output of the subtractor 3, free from the drift of the SDS 1, as well as from the angular velocity component along the OY axis in the coordinate system associated with the earth (at a non-zero pitch angle). A signal proportional to the angular velocity along the OX axis of the associated coordinate system then goes to the integrator 4, which calculates the roll angle of the aircraft by integrating the angular velocity along the OX axis. Data on the current angle of heel is fed to a subtractor 5, which calculates the error between the desired and current value of the heel. The calculated error arrives at the isodromic link 7, which generates control actions through the block generating PWM signals 38 on the actuator - ailerons 39.

The signal from the angular velocity sensor along the OY 8 axis in the associated coordinate system is fed to the input of the ADC 9. The signal from the CRS 8 is used in the correction system of the CRS 1 readings.

Correction of the readings of the CRS 1 is due to the ability to calculate the roll of the aircraft through the connection of the radius of the turn and the airspeed of the aircraft. When integrating the CRS 1, an error inevitably occurs due to the zero offset of the angular velocity sensor, noise, and the presence of a nonzero pitch angle.

In general, the signal from TLS 1 through OX can be written as follows:

,

Where ω _X is the angular velocity at the output of the sensor;

Ω _X - True angular velocity along the OX axis in the associated coordinate system;

Offset - Offset (drift) of the sensor zero;

N - Sensor Noise;

Ω _Y The angular velocity along the normal axis OY in the coordinate system associated with the earth;

Roll - roll angle of the aircraft.

For the correct calculation of the roll angle, it is necessary to subtract all components not related to Ω _X before integration.

To solve this problem, the roll angle of the aircraft is additionally calculated in block 10 using signals from the CRS 8 along the OY axis in the associated coordinate system and airspeed information from block 19.

From the equation of the dynamics of movement of the aircraft it is known that the radius of the turn is calculated as (in a coordinated turn):

where, R - Radius of a turn;

U - Airspeed

g is the acceleration of gravity (at Earth)

Roll - True roll angle

From here you can find the angular velocity along the normal axis OY (in the coordinate system associated with the ground):

Full-circle circumference

Time for the plane to complete a full U-turn

The angular velocity along the normal axis OY (in the coordinate system associated with the ground)

The angular velocity in the coordinate system associated with the aircraft (which will be shown by the TLS installed along the OY axis) will differ from Ω _Y due to the angle of heel.

The angular velocity shown by the TLS along the OY axis taking into account the roll can be calculated as

From here we calculate the angle of heel:

This calculation is performed by block 10.

As we see in this equation, errors that occur in the CRS 8 along the OY axis do not accumulate, but only distort the result of measuring the angle of heel. In the same way, the airspeed measurement error also affects the roll calculation result.

The estimated roll angle calculated by block 10 then goes to the nonlinear link 11, which compensates for the inevitable occurrence of sliding at large roll angles (more than 30 degrees).

The calculated roll angle by blocks (10, 11) is compared with the calculated roll as a result of integration of the CRS 1 along the OX axis in block 12, as a result, an error signal of the calculated roll angle appears, which arrives at the filter consisting of blocks 13, 14, 15, 16, representing a modified isodromic link with the addition of a limiter to the output of the integrator.

Thus, by calculating the angle of heel in two different ways (by integrating the TLS 1 and complex processing of the signals from the TLS 8 and airspeed information from block 19), it becomes possible to isolate the TLS offset along the OX axis and subtract it in block 3 in front of the integrator 4.

The signal from the differential pressure sensor 17 is used to measure airspeed. Its signal is fed to the input of the ADC 18, and then to the airspeed calculator 19, in which the airspeed is calculated according to the readings of the differential pressure sensor 17. The airspeed calculated in block 19 is used in the airspeed stabilization circuit (blocks 20, 21, 40, 41 ) and in the roll correction system (blocks 10, 11, 12, 13, 14, 15, 16). The engine speed stabilization circuit consists of a subtractor 20, the inputs of which receive the required airspeed signals from the interface module 34, and information about the current airspeed from module 19. The difference between these values at the output of module 20 is an airspeed error signal, and is sent to the isodromic link 21, which generates a motor control signal through a PWM signal generating unit 41 to an actuator 40.

The full pressure sensor 22 is used in the system for measuring barometric altitude. The signal from the sensor 22 is fed to the input of the ADC 23, and then to block 24, which performs the conversion of the total pressure into barometric altitude information. The calculated barometric altitude is used in the height stabilization loop. To maintain a given height without information about the pitch angle, the system uses the calculation of the vertical speed, which is carried out by blocks 25, 26, 27. The input of the differentiating link 25 receives information on the barometric height from block 24. Since the signal contains high-frequency noise, then after differentiation, in addition to the signal vertical speed at the output of block 25 there are amplified noises. To suppress the RF components from the output of block 25, a low-pass filter of order 26 is used. To convert the vertical speed to m / s, the proportional link 27 is used. Thus, a vertical speed signal is generated at the output of block 27. To control the height, the required vertical speed is calculated in blocks 30, 31, 32. In the subtractor 30, the current height (from block 24) and the required height (from block 34) are compared. At the output of the subtractor 30, a signal is generated proportional to the height error. This signal is supplied to the proportional link 31, which performs the conversion of the height error in the desired vertical speed. The output of the proportional link 31 is connected to the limiter 32, which is needed to limit the required vertical speed with large height errors. The limitation of the required vertical speed is associated with the physical capabilities of the aircraft to ensure safe flight.

The required vertical speed, depending on the error of heights, is formed at the output of block 32, and is fed to a subtractor 28, which generates an error signal of vertical speeds. From the output of the subtractor 28, a signal proportional to the error of vertical speeds is fed to the isodromic link 29, which generates a signal to control the actuator - elevator 43. The signal from block 29 passes through the PWM signal generating unit 42 and is transmitted to the actuator 43.

To move the UAV along a given trajectory, the system uses a navigation unit 37. This unit receives a signal from the receiver of the satellite navigation system (SNA) 35, as well as from the non-volatile memory module 36, in which the flight route is laid. The navigation unit 37 compares the current and required coordinates, calculates the required course, and depending on the error between the current course and the desired course, generates the required roll signal, which is fed to the control mode switch 6. The signal of the required roll from the interface module is received at the other input of the switch 6 34.

Also, from the module 34, the switch 6 receives a signal for selecting a control mode - “automatic” or “semi-automatic”. The signal from the output of the switch 6 is fed to the subtractor 5, the output of which is the roll error signal. In automatic mode, the required roll is set from the navigation unit 37 in order to ensure UAV movement along a given route, while switch 6 passes the signal of the required roll to the input of block 5 from block 37, and blocks the signal of the required roll from block 34. In semi-automatic mode, the required roll is set interface module according to operator’s commands. In semi-automatic mode, the switch 6 passes the signal of the required bank to the input of block 5 from block 34, and blocks the signal of the required bank from block 37.

Thus, the proposed developed system allows the use of a reduced set of sensors. To calculate Euler angles (roll, pitch, course), only 2 DUSs along the X and Y axes are used, as well as a height and airspeed sensor. It does not require a full six-degree platform of inertial sensors (3 accelerometers, 3 gyroscopes), as well as free gyroscopes.

Claims (1)

The automatic control system for an unmanned aerial vehicle, which includes roll and heading angular velocity sensors, differential and total pressure sensors, analog-to-digital converters, a computer for programmatically processing signals from sensors and generating control signals, control signal generation blocks for actuators, actuators, and also a satellite navigation system receiver, characterized in that for calculating the angular position of the unmanned aerial vehicle (UAV) it uses only two angular velocity sensors and full and differential pressure sensors, the outputs of which are connected to the inputs of the corresponding analog-to-digital converters, which in turn are connected to a computer that contains program blocks that allow you to correct signals from the angular velocity sensors (DLS) ) and provide an estimate of the angular position of the aircraft (LA) without using the signals of the satellite navigation system (SNA), while the calculator contains program modules, containing subtractors, proportional and isodromic links connected to PWM signal generating units and actuators, allowing UAV control in roll, heading and pitch channels, and the system is equipped with a satellite navigation system receiver and a non-volatile memory module for introducing geographical coordinates information into the system aircraft locations.