A control system for a drone

Abstract

The application relates to the technical field of automatic control of unmanned aerial vehicles, in particular to a control system of an unmanned aerial vehicle, which comprises a bus, a self-pilot, a plurality of rudder controllers and a plurality of rudder surface driving mechanisms, the self-pilot and each rudder controller are connected to the bus, each rudder controller is electrically connected with the corresponding rudder surface driving mechanism; each rudder controller is provided with a control distribution table mapped with a flight configuration; during the flight of the unmanned aerial vehicle, each rudder controller determines the corresponding control distribution table according to the flight configuration broadcast by the self-pilot; according to the control distribution table, the weight of each control signal participating in control is determined, and the total control signal is obtained by weighted summation of each control signal participating in control; each rudder controller outputs the total control signal to the corresponding rudder surface driving mechanism to realize the control of the rudder surface driving mechanism. That is, the application scheme can relieve the operation and storage pressure of the self-pilot, simplify the configuration of the self-pilot and improve the universality of the self-pilot.

Description

A control system for unmanned aerial vehicles Technical Field

[0001] This invention generally relates to the field of automatic control of unmanned aerial vehicles (UAVs). More specifically, this invention relates to a control system for a UAV. Background Technology

[0002] With the continuous development of technology, unmanned aerial vehicle (UAV) systems are being used more and more widely in various fields. These applications include, but are not limited to, military, civilian, and scientific research. In the military field, UAV systems can be used for reconnaissance, surveillance, and strike missions. In the civilian field, UAV systems can be used for aerial photography, logistics delivery, and environmental monitoring. In the field of scientific research, UAV systems can be used for geological exploration and environmental change monitoring.

[0003] An unmanned aerial vehicle (UAV) system consists of a UAV, a ground control station, and a data link. The core component of the UAV system is the UAV. The ground control station is the control center of the UAV, capable of monitoring and controlling its flight and mission execution in real time. The data link is the communication system between the UAV and the ground control station, used to transmit data and commands between them.

[0004] In existing drones, the autopilot (also known as the flight controller) and servos are directly connected by wires. The autopilot outputs PWM waveform control signals to the servos via wires, causing the servos to drive the drone's control surfaces. It should be noted that drones have many control surfaces, each driven by a servo, and the servos are located relatively far apart on the drone. Therefore, connecting them with straight wires not only results in a large number of wires and a messy layout, but also leads to some wires extending too far, resulting in greater signal loss and susceptibility to interference during control signal transmission.

[0005] Based on the above problems, application publication number CN 106789501 A, entitled "A Bus Control System and Method for a Cascaded Unmanned Aerial Vehicle Power System," discloses a method that involves setting up a flight controller bus drive module and a drive bus; the flight controller bus drive module is connected to the drive bus, and sends speed control signals to the electronic speed controller in real time via the bus to control the motor operation in real time; this solves the problems of numerous and messy wires and high control signal transmission loss. However, the flight controller's control of the electronic speed controller involves multiple control signals mixed together, and it does not provide specific control methods.

[0006] Currently, multiple control quantities are generally mixed and controlled through an autopilot. In this case, the autopilot not only needs to store a large amount of control data, but also needs to calculate the actual control signals of the control surfaces. Therefore, the autopilot has a large computational and storage burden, complex control, and low versatility. Summary of the Invention

[0007] To address one or more of the aforementioned technical problems, this invention proposes to establish a bus for communication between the autopilot and the servo controller, thus resolving the issues of high transmission loss of control signals and numerous, chaotic wires. Furthermore, by setting a control allocation table in each servo controller, the total control signal can be calculated by the servo controller when multiple control signals are mixed, reducing the computational and storage burden on the autopilot. Therefore, this invention provides a solution in one of the following aspects.

[0008] The present invention provides a control system for an unmanned aerial vehicle (UAV), including a bus, an autopilot, multiple servo controllers, and multiple control surface drive mechanisms; the autopilot and each of the servo controllers are connected to the bus; each servo controller is electrically connected to a corresponding control surface drive mechanism, and each control surface drive mechanism is used to drive the corresponding UAV control surface;

[0009] Each of the aforementioned servo controllers is equipped with a control allocation table that maps to the flight configuration of the UAV; the control allocation table is used to identify the control signals involved in the control and to provide the weights of the control signals involved in the control.

[0010] During the flight of the UAV, the autopilot broadcasts the current flight configuration and current control signals through the bus; the servo controller determines the current control allocation table based on the current flight configuration, and determines the current control signals participating in the control and their weights based on the current control allocation table; the servo controller performs a weighted summation of all the current control signals participating in the control according to their corresponding weights to obtain a total control signal, and outputs the processed total control signal to the corresponding control surface drive mechanism to control the corresponding control surface drive mechanism to drive the corresponding UAV control surface.

[0011] Optionally, the servo controller receives the current flight configuration broadcast by the autopilot and determines the current control allocation table based on the current flight configuration and the mapping relationship; wherein, the mapping relationship for each servo controller is such that one flight configuration corresponds to one control allocation table; and one control allocation table corresponds to at least one flight configuration.

[0012] Optionally, the flight configuration includes at least one of the following: takeoff configuration, cruise configuration, landing configuration, go-around configuration, hovering configuration, and low-speed hovering configuration.

[0013] Optionally, the control allocation table can identify up to four control signals participating in the control, each control signal participating in the control corresponding to a weight, and the sum of the weights of all control signals participating in the control in the control allocation table is 1.

[0014] Optionally, the control allocation table includes a mask for identifying control signals participating in the control, wherein the number of bits in the mask is equal to the number of types of control signals, and each bit of the mask corresponds to one type of control signal; when the control signal participates in the control of the servo controller, the bit of the mask corresponding to the control signal is 1; when the control signal does not participate in the control of the servo controller, the bit of the mask corresponding to the control signal is 0.

[0015] Optionally, the control surface drive mechanism includes a servo motor or an electronic speed controller (ESC), the servo motor controller is electrically connected to the servo motor or ESC, and the servo motor or ESC is connected to the control surface of the UAV.

[0016] Each of the aforementioned servo controllers is further configured to collect the operating parameters of the control surface drive mechanism and report the operating parameters to the autopilot via the bus; each of the aforementioned servo controllers is further configured to determine the error state of the control surface drive mechanism based on the operating parameters and report the error state of the control surface drive mechanism to the autopilot via the bus.

[0017] Optionally, the control system of the UAV also includes a ground station, which communicates wirelessly with the autopilot, and the control allocation table is configured in real time through the ground station.

[0018] Optionally, the control system of the UAV is used in at least one of a fixed-wing UAV, a rotary-wing UAV, and a compound-wing UAV;

[0019] The control surfaces of the UAV include control surfaces of fixed-wing UAVs and control surfaces of rotary-wing UAVs; the control surfaces of the fixed-wing UAVs include at least one of the following: ailerons, elevators, rudders, flaps, spoilers, drag rudders, V-tail control surfaces, split aileron rudders, and elevators; the control surfaces of the rotary-wing UAVs include hovering motors.

[0020] Optionally, the control signal includes at least one of the following: roll control signal, pitch control signal, yaw control signal, throttle control signal, brake control signal, flap control signal, spoiler control signal, and front wheel steering control signal.

[0021] Optionally, the control system of the UAV also includes other bus devices, all of which are connected to the bus; the autopilot and the other bus devices communicate with each other through the bus; the bus is a CAN bus.

[0022] The beneficial effects of this invention are as follows:

[0023] The present invention solves the problems of high transmission loss of control signals and numerous, messy wires by setting up a bus for communication between the autopilot, servo controller, and other bus devices. By setting a control allocation table in the servo controller, the servo controller can calculate the total control signal when multiple control signals are mixed to control a single control surface drive mechanism. It can then process the total control signal into a signal recognizable by the control surface drive mechanism and output it to the control surface drive mechanism. This not only reduces the power consumption during control signal transmission to the control surface drive mechanism but also reduces the computational and storage burden on the autopilot, simplifying its configuration.

[0024] When in use, the autopilot only needs to broadcast the current flight configuration and basic control signals of the UAV. The mixed control calculation of the control surface drive mechanism is handed over to the servo controller, which allows the autopilot to be quickly adapted to different UAVs without spending a lot of time configuring the data in the autopilot, making the autopilot more versatile. Attached Figure Description

[0025] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0026] Figure 1 is a first structural block diagram of a control system for an unmanned aerial vehicle according to this embodiment;

[0027] Figure 2 is a second structural block diagram of a control system for an unmanned aerial vehicle (UAV) according to this embodiment. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] Figure 1 is a first structural block diagram of a control system for an unmanned aerial vehicle (UAV) according to this embodiment.

[0031] As shown in Figure 1, the UAV control system includes an autopilot, a bus, multiple servo controllers, and multiple control surface drive mechanisms. The autopilot is connected to each servo controller via the bus, and each servo controller is electrically connected to the control surface drive mechanism. Each control surface drive mechanism is used to drive the corresponding UAV control surface.

[0032] Specifically, the autopilot sends control signals to each servo controller via a bus. Each servo controller processes and analyzes the received control signals to obtain a total control signal, which is then converted into actual control signals and output to the control surface drive mechanism. The control surface drive mechanism drives the corresponding UAV control surfaces based on the actual control signals. The actual control signals can be PWM signals or RS485 bus signals, etc.

[0033] Buses include, but are not limited to, CAN bus, RS485 bus, etc. In this embodiment, CAN bus is used for communication connection. Since the physical connection of CAN bus only requires two wires and CAN bus transmits data through differential signals, using CAN bus for connection and communication between the drone and the autopilot and various devices not only helps to reduce the number of wires on the drone, but also helps to improve the anti-interference capability of signal transmission.

[0034] The system includes multiple servo controllers, such as a first servo controller, a second servo controller, ..., an nth servo controller, where n is greater than or equal to 1. The autopilot is connected to the n servo controllers in a cascaded manner. Each servo controller includes an MCU chip and a bus transceiver. The MCU chip has functions such as storage, calculation, and parameter configuration. The servo controller may also include power supply adjustment devices such as capacitors, resistors, and voltage regulator modules.

[0035] In addition, the servo controller may also include a current acquisition module, which is used to acquire the current of the control surface mechanism such as the servo or ESC connected to the servo controller; the servo controller may also include a position acquisition module, which is used to acquire the position of the control surface mechanism such as the servo connected to the servo controller; the servo controller may also be equipped with other acquisition modules as needed, which are used to acquire other operating parameters of the control surface drive mechanism.

[0036] The servo controller can determine the operating status of the control surface mechanism based on its operating parameters. The operating status of the control surface mechanism includes, but is not limited to, normal operating status and abnormal operating status. For example, the servo controller can analyze whether the servo is operating normally or stuck based on the collected servo current and servo position data. The servo controller can also analyze whether the ESC is operating normally or overloaded based on the collected ESC current data. The servo controller can report the operating status of the control surface drive mechanism to the autopilot via the bus. Furthermore, the servo controller can report the operating parameters of the control surface drive mechanism or other configuration parameters to the autopilot via the bus as needed.

[0037] The control surface drive mechanism is correspondingly configured with the servo controller, including a first control surface drive mechanism, a second control surface drive mechanism, ..., an nth control surface drive mechanism. Each control surface drive mechanism includes a servo and a linkage. The servo controller is connected to the servo, and the servo's rocker arm is connected to the control surface via the linkage. The servo controller controls the servo to drive the linkage via the rocker arm, which in turn drives the control surface. Alternatively, the servo controller can be independent of the servo, or it can be integrated into the servo's housing.

[0038] The control surface drive mechanism can also be an electronic speed controller (ESC), which is electrically connected to the motor to drive the motor's operation.

[0039] For example, the throttle of an electric drone and the hover motor of a rotary-wing drone are controlled by electronic speed controllers (ESCs), while some control surfaces such as ailerons, elevators, and rudders are driven by servos. Therefore, whether the control surface drive mechanism is a servo or an ESC depends on the type of drone control surface. For example, drone control surfaces include those of fixed-wing drones and rotary-wing drones; the control surfaces of fixed-wing drones include, but are not limited to: ailerons, elevators, rudders, flaps, spoilers, drag rudders, V-tail control surfaces, split aileron rudders, and elevators; the control surfaces of rotary-wing drones include, but are not limited to, hover motors.

[0040] For fixed-wing UAVs, when the servo controller is connected to the servo and / or ESC, its operation is as follows: the servo is connected to the UAV's control surfaces. The servo controller can calculate and process the control signals sent by the autopilot to obtain the overall control signal, and then output this overall control signal to the servo so that the servo drives the UAV's control surfaces. Control surfaces driven by servos on UAVs include, but are not limited to: ailerons, elevators, rudders, flaps, spoilers, and nose wheel steering. Additionally, the throttle servo of a gasoline-powered UAV can also be equipped with a servo controller. The throttle servo does not require mixed control of multiple control signals; therefore, in the throttle servo controller's allocation table, the weight of the throttle control signal is always 1, and the weight of other control signals is always zero.

[0041] For multi-rotor drones (such as quadcopters), the operation process is as follows: the electronic speed controller (ESC) is connected to the drone's hover motor. The servo controller calculates and processes the control commands issued by the autopilot to obtain a total control signal, which is then converted and output to the ESC to control the speed of the multi-rotor drone's hover motor. Motors controlled by the ESC on a drone can also include: the drone's throttle motor, which utilizes a motor and propeller for power.

[0042] For example, in this embodiment, the value of n can be 3, that is, three servo controllers are set, including elevator servo controller, rudder servo controller, and aileron servo controller, which respectively control the elevator servo, rudder servo and aileron servo.

[0043] Similarly, for a quadcopter drone, four electronic speed controllers (ESCs) can be set up and electrically connected to the servo controllers. Each servo controller corresponds to one ESC, and the actual control signal is sent to the ESC so that the ESC controls the speed of the drone's motors, that is, controls the speed of the propellers, in order to change the drone's flight state.

[0044] In this embodiment, each servo controller stores a configured control allocation table. Based on the flight configuration broadcast by the autopilot, the servo controller automatically switches to the control allocation table corresponding to that flight configuration. One flight configuration corresponds to one control allocation table, and one control allocation table can correspond to one or more flight configurations; that is, the allocation tables corresponding to different flight configurations may be the same or different. Therefore, each servo controller can store one or more control allocation tables. If the allocation tables corresponding to each flight configuration are the same, then the servo controller may only store one allocation table. The control allocation tables stored in different servo controllers may be the same or different.

[0045] It should be noted that flight configurations include, but are not limited to, takeoff configuration, cruise configuration, landing configuration, go-around configuration, hovering configuration, and low-speed hovering configuration. Various configurations can be pre-configured in the autopilot. Specifically, the operation process of the UAV control system in this embodiment is as follows:

[0046] During the flight of the UAV, the autopilot broadcasts the current flight configuration and current control signals via the bus; the servo controller determines the current control allocation table based on the current flight configuration, and determines the current control signals involved in the control and their weights based on the current control allocation table; the servo controller performs a weighted summation of all the current control signals involved in the control according to their corresponding weights to obtain the total control signal, and outputs the total control signal after processing to the corresponding control surface drive mechanism to control the corresponding control surface drive mechanism to drive the corresponding UAV control surface.

[0047] The control system of the UAV of the present invention may further include a ground station, which communicates wirelessly with the autopilot. The control allocation table can be pre-configured and stored in the servo controller, or it can be configured in real time through the ground station. The ground station transmits the control allocation table to the autopilot, and the autopilot transmits it to the servo controller via a bus.

[0048] In this embodiment, each servo controller can receive the current control signal broadcast by the autopilot via the bus. Each servo controller determines the current control allocation table according to the current flight configuration, and processes the current control signal on the bus according to the control allocation table to obtain the total control signal of the servo / ESC corresponding to each servo controller. After converting the total control signal (i.e., the servo controller processes the total control signal into a PWM waveform signal that the servo can recognize), it is output to the corresponding servo and / or ESC.

[0049] It should be noted that a control surface drive mechanism can be controlled by a combination of multiple control signals on the bus. Therefore, when multiple control signals control a control surface drive mechanism at the same time, there is a problem of complex control logic. Therefore, in this embodiment, by processing the multiple control signals of the mixed control to obtain a single actual control signal, the multiple control signals can be converted into a single overall control signal to control the control surface drive mechanism, and the control logic is simpler.

[0050] The process by which each servo controller in the above-mentioned configuration processes the current control signals broadcast on the bus according to the control allocation table is as follows:

[0051] 1) Obtain the configured control allocation table. The control allocation table includes a mask for identifying the control signals involved in the control and the weights of the control signals involved in the control. The number of bits in the mask is equal to the number of control signal types. Each bit of the mask corresponds to one type of control signal. When a control signal participates in the control of the servo controller, the bit of the mask corresponding to that control signal is 1; when a control signal does not participate in the control of the servo controller, the bit of the mask corresponding to that control signal is 0. For example, the mask can be four bits, corresponding to the roll control signal, pitch control signal, yaw control signal, and throttle control signal from high to low. When the pitch control signal and yaw control signal participate in the control, and the roll control signal and throttle control signal do not participate in the control, the mask is represented as 0110. The weights of the pitch control signal and yaw control signal can be set to 0.5 and 0.5 respectively, depending on actual needs.

[0052] The weights of the control signals involved in the control can be set manually based on experience; alternatively, the weights of different control signals can be determined by analyzing the importance of the control signals involved in the control of the same rudder surface drive mechanism.

[0053] This embodiment analyzes the importance of control signals involved in the control of the same servo motor, and the process of determining the weight of different control signals includes:

[0054] Real-time acquisition of the command position corresponding to each control signal among the control signals involved in the control;

[0055] Calculate the deviation between each instruction position and the corresponding actual position, normalize the deviation, and obtain the deviation value.

[0056] Obtain the sequence of each deviation value, calculate the variance of each deviation value sequence, and use each variance as the volatility of each control signal;

[0057] The volatility is sorted from smallest to largest, and the weights are allocated according to the sorting order.

[0058] For example, the allocation rules could be:

[0059] When there are two control signals with similar volatility, the weights are both set to 0.5. When the volatility differs significantly, the signal with lower volatility is weighted at a value greater than 0.5, and the other signal is weighted at a value less than 0.5. When there are three control signals with similar volatility, the weights are evenly distributed. When the volatility of the three signals differs significantly, their importance is set in ascending order of volatility, i.e., the signal with the lowest volatility is weighted at a value greater than 0.5, the signal with the highest volatility is weighted at 0.2, and the signal in the middle is weighted at 0.3.

[0060] The distinction between similar and significantly different volatility can be made by setting volatility thresholds based on historical data.

[0061] In this embodiment, the weights are allocated based on the volatility of the control signals. This reduces the importance of control signals with high volatility and highlights the accuracy of control signals with high accuracy, thereby enabling more precise control of the UAV.

[0062] It should be noted that the above is only one embodiment of obtaining weights, and it can be set according to the actual situation and is not limited to the above embodiment; at the same time, the weight setting also needs to be reasonably allocated in combination with the current operating attitude of the UAV.

[0063] For example, the control allocation table is shown in Table 1, including the mask and weights. It should be noted that Table 1 is a control allocation table common to both fixed-wing UAVs and quadcopter UAVs.

[0064] Table 1

[0065]

[0066] In Table 1, bytes 1 and 2 are the mask, which consists of 16 bits. Each bit represents the participation state of a control signal, meaning the mask can represent a maximum of 16 control signal participation states. For fixed-wing UAVs, the control signals broadcast by the autopilot on the bus include: roll control signal, pitch control signal, yaw control signal, throttle control signal, brake control signal, flap control signal, spoiler control signal, and front wheel steering control signal. For rotary-wing UAVs, the control signals broadcast by the autopilot on the bus include: roll control signal, pitch control signal, yaw control signal, throttle control signal, control signals from auxiliary channel 1, auxiliary channel 2, auxiliary channel 3, and auxiliary channel 4. Therefore, there are a total of 16 control signals for both types of UAVs.

[0067] In this embodiment, a one-to-one correspondence between a 16-bit mask and 16 control signals can be predefined. For example, the 8 bits of byte 1, from bit 15 to bit 8, can sequentially correspond to the roll control signal, pitch control signal, yaw control signal, throttle control signal, brake control signal, flap control signal, spoiler control signal, and front wheel steering control signal of a fixed-wing UAV; the 8 bits of byte 2, from bit 7 to bit 0, can sequentially correspond to the roll control signal, pitch control signal, yaw control signal, throttle control signal, control signal of auxiliary channel 1, control signal of auxiliary channel 2, control signal of auxiliary channel 3, and control signal of auxiliary channel 4 of a multi-rotor UAV. This allows the autopilot to quickly switch between fixed-wing and multi-rotor aircraft.

[0068] Table 1 shows the weights of the four control signals involved in the control process, from d1 to d4. d1 to d4 correspond one-to-one with the control signals involved in the control process, following the order of the high-order bits (bit15 to bit0) of the mask. It should be noted that the number of control signals involved in controlling a single control surface drive mechanism typically does not exceed four. Therefore, the control allocation table of the servo controller can identify a maximum of four control signals involved in the control process, and Table 1 only reserves four bytes for setting weights. It can be understood that the sum of the weights of all control signals involved in the control process determined by the control allocation table is 1.

[0069] 2) The servo controller maps the received current control signal to the mask in the control allocation table to obtain the type of control signal participating in the control. Then, it maps the control signal participating in the control to the weight to obtain the weight of the control signal participating in the control.

[0070] 3) The servo controller performs a weighted summation of the control signals involved in the control according to their respective weights to obtain the total control signal, and then converts the total control signal into an actual control signal that can be recognized by the servo drive mechanism and outputs it to the servo drive mechanism.

[0071] For example, for a fixed-wing UAV, the control signals broadcast by the autopilot may include roll control signals, pitch control signals, yaw control signals, and throttle control signals. For a servo on a specific control surface, its servo controller can determine which one or more control signals are involved in the control according to the control allocation table of the servo controller, determine the weight of the control signals involved in the control, and perform a weighted sum of the control signals involved in the control according to their respective weights to obtain the total control signal, which is then processed into the actual control signal for controlling the servo.

[0072] Specifically, for the servo controller of the V-tail control surface of a V-tail fixed-wing UAV, the 16-bit mask in its control allocation table can be: 0110 0000 0000 0000. Based on the correspondence between the mask and control signals specified above, it can be deduced that pitch control and yaw control signals simultaneously participate in the control of the V-tail control surface. In the control allocation table, d1 and d2 represent the participation weights of the pitch and yaw control signals, respectively, while d3 and d4 can be filled with 0 or invalid characters. During the flight of the V-tail fixed-wing UAV, the servo controller of the V-tail control surface receives control signals broadcast on the bus by the autopilot, maps them to the mask in the control allocation table, determines that the pitch and yaw control signals participate in the control of the V-tail control surface, and maps the pitch and yaw control signals to d1 and d2 to determine their weights. At this time, the total control signal controlling the V-tail control surface = pitch control signal × d1 + yaw control signal parameter × d2.

[0073] It should be noted that some servo drive mechanisms do not involve mixed control of multiple control signals. For example, throttle servos (Electronic Speed ​​Controllers): the only control signal involved in their control is the throttle control signal, and the weight of the throttle control signal is always 1. In this case, the servo controller corresponding to the throttle servo (Electronic Speed ​​Controller) does not need to have a control allocation table set. Front wheel steering servos: since they only follow the front wheel steering control signal, the weight of the front wheel steering control signal is always 1. In this case, the servo controller corresponding to the front wheel steering servo also does not need to have a control allocation table set.

[0074] For ordinary servos and left and right resistance rudders (opening and closing type) servos, there is a mixture of control signals. In the weighted summation process, the servo controller will first multiply the control signals that have been normalized (±1) by their weights, then add them together, and finally limit them to 0~1 or -1~0 in order to obtain the total control signal.

[0075] Specifically, taking the servo motor controlling the elevators when a fixed-wing UAV turns as an example, we will introduce the normalization process of the control signal during weighted summation:

[0076] For the servo controlling the elevons, two control signals, roll control and pitch control, can participate in the mixed control. The broadcast roll control signal is within the range of ±32767, and the pitch control signal is also within the range of ±32767. It should be emphasized that the range of ±32767 is only a defined example, and other ranges are possible. After the control signals are transmitted to the servo controller, they are first normalized (±1), and then weighted and summed to obtain the total control signal: roll control signal × n1 + pitch control signal × n2. The weights of the roll control signal and the pitch control signal are n1 and n2, respectively. Finally, the total control signal is converted into a PWM waveform that the servo can recognize to control the servo. The PWM waveform can be understood as the processed actual control signal.

[0077] For example, for a quadcopter drone, the control commands issued by the autopilot may include: roll control signal, pitch control signal, yaw control signal, and throttle control signal. For a specific hover motor ESC, its servo controller can determine which one or more control signals are involved in the control according to the control allocation table of the servo controller, determine the weight of the control signals involved in the control, and perform a weighted sum of the control signals involved in the control according to their respective weights to obtain the total control signal, which is then processed into the actual control signal for controlling the ESC.

[0078] Furthermore, the servo controller can also set the servo's vertical travel, neutral point, curve, speed limit control, etc.; detect the servo position and servo current and report them to the bus; it can also report error codes to the autopilot via the bus, each error code corresponding to an error state of the servo, and error states include, but are not limited to:

[0079] 1. Servo motor not connected (current is zero);

[0080] 2. Servo malfunction (the actual position commanded by the control signal differs from the actual position detected by the sensor by more than 20%).

[0081] 3. Servo motor jamming (command changes but actual position does not change or changes very little or current is too high).

[0082] In another possible implementation, the control allocation table includes the weights of all control signals broadcast by the autopilot, where control signals not involved in control have a weight of 0, and control signals involved in control have a weight that is not equal to 0. Specifically, the servo controller of a specific control surface drive mechanism receives all control signals broadcast on the bus and maps all control signals to the weights in the control allocation table to determine the weight of each control signal. Then, all control signals are weighted and summed according to their respective weights to obtain the total control signal. It is understandable that since the weight of control signals not involved in control is 0, they do not contribute to the total control signal obtained by the weighted summation.

[0083] It is understood that the control system of the UAV of the present invention can be used not only in fixed-wing UAVs and rotary-wing UAVs, but also in compound-wing UAVs that combine fixed-wing and rotary-wing technologies.

[0084] Figure 2 is a second structural block diagram of a control system for an unmanned aerial vehicle (UAV) according to this embodiment.

[0085] Furthermore, as shown in Figure 2, the control system of the UAV of the present invention may also include: an atmospheric data module, an engine monitoring module, a landing gear control module, a power control module, and a fuel supply monitoring module.

[0086] The atmospheric data unit has the following functions: collecting total pressure, dynamic pressure, temperature, angle of attack, and sideslip angle, and reporting them to the autopilot via the bus.

[0087] The functions of the engine monitoring module include: collecting speed, pitch, temperature, and current.

[0088] The functions of the landing gear control module include: 1. Sequential control of the retraction and extension of the landing gear and landing gear doors according to configuration instructions; 2. Determining whether the steering wheels need to operate based on the ground clearance status; 3. Monitoring the status of each sensor on the landing gear.

[0089] The functions of the power control module include: 1. power supply control; 2. charging control; 3. output control, etc.

[0090] The functions of the fuel supply monitoring module include: estimating the remaining fuel, remaining flight time, and mileage.

[0091] In this embodiment, the aforementioned atmospheric data module, engine monitoring module, landing gear control module, power control module, and fuel supply monitoring module are collectively referred to as other bus devices. These other bus devices are connected to the bus and communicate with the autopilot via the bus. Specifically, the autopilot forwards configuration command information from the host computer to the other bus devices and sends the configuration status information returned by the other bus devices to the host computer; the autopilot saves the configuration information and access status of the other bus devices; the autopilot sends corresponding control commands to the other bus devices; the autopilot monitors / uses the other bus devices and reports information to the ground station.

[0092] The solution of this invention, through bus communication, can reduce the number of wires and avoid confusion; at the same time, it can also avoid the problem of excessive loss during control signal transmission due to the long extension of some wires; and the bus communication is not easily interfered with during control signal transmission.

[0093] Meanwhile, the solution of the present invention, by setting a control allocation table in the servo controller, enables a certain control surface drive mechanism to reduce the computation and storage pressure of the autopilot by calculating the total control signal of multiple control signals under the mixed control of multiple control signals. The autopilot only needs to broadcast the flight configuration and basic control signals, so that the autopilot can be quickly adapted to different UAVs without spending a lot of time configuring the data in the autopilot, making the autopilot more versatile.

[0094] It should be noted that the terms "first", "second", ..., "nth" in the above embodiments are only used to distinguish different objects and are not used to describe a specific order.

[0095] While this specification has shown and described numerous embodiments of the invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of this invention.

Claims

1. A control system for an unmanned aerial vehicle (UAV), characterized in that, The system includes a bus, an autopilot, multiple servo controllers, and multiple control surface drive mechanisms. The autopilot and each servo controller are connected to the bus. Each servo controller is electrically connected to its corresponding control surface drive mechanism, which drives the corresponding UAV control surface. Each servo controller has a control allocation table mapped to the UAV's flight configuration. The control allocation table identifies control signals participating in control and provides their weights. During UAV flight, the autopilot broadcasts the current flight configuration and current control signals via the bus. The servo controllers determine the current control allocation table based on the current flight configuration and, based on the current control allocation table, determine the control surfaces participating in control. The current control signals and their weights are defined as follows: The servo controller performs a weighted summation of all current control signals participating in the control according to their corresponding weights to obtain a total control signal, and outputs the processed total control signal to the corresponding control surface drive mechanism to control the corresponding control surface drive mechanism to drive the corresponding UAV control surface; The control allocation table includes a mask for identifying control signals participating in the control, the number of bits in the mask is equal to the number of types of control signals, and each bit of the mask corresponds to one type of control signal; when the control signal participates in the control of the servo controller, the bit in the mask corresponding to the control signal is 1; when the control signal does not participate in the control of the servo controller, the bit in the mask corresponding to the control signal is 0.

2. The control system for the unmanned aerial vehicle according to claim 1, characterized in that, The servo controller receives the current flight configuration broadcast by the autopilot and determines the current control allocation table based on the current flight configuration and the mapping relationship; wherein, the mapping relationship of each servo controller is that one flight configuration corresponds to one control allocation table; and one control allocation table corresponds to at least one flight configuration.

3. The control system for the unmanned aerial vehicle according to claim 1, characterized in that, The flight configurations include at least one of the following: takeoff configuration, cruise configuration, landing configuration, go-around configuration, hovering configuration, and low-speed hovering configuration.

4. The control system for the unmanned aerial vehicle according to claim 1, characterized in that, The control allocation table identifies at most four control signals participating in the control. Each control signal participating in the control corresponds to a weight, and the sum of the weights of all control signals participating in the control in the control allocation table is 1.

5. The control system for the unmanned aerial vehicle according to claim 1, characterized in that, The control surface drive mechanism includes a servo motor or an electronic speed controller (ESC). The servo motor controller is electrically connected to the servo motor or ESC, and the servo motor or ESC is connected to the control surface of the UAV. Each servo motor controller is also used to collect the operating parameters of the control surface drive mechanism and report the operating parameters to the autopilot via the bus. Each of the aforementioned servo controllers is further configured to determine the error state of the servo surface drive mechanism based on the operating parameters, and report the error state of the servo surface drive mechanism to the autopilot via the bus.

6. The control system for the unmanned aerial vehicle according to any one of claims 1-5, characterized in that, The control system of the UAV also includes a ground station, which communicates wirelessly with the autopilot, and the control allocation table is configured in real time through the ground station.

7. The control system for the unmanned aerial vehicle according to any one of claims 1-5, characterized in that, The control system of the UAV is used in at least one of a fixed-wing UAV, a rotary-wing UAV, and a compound-wing UAV; the control surfaces of the UAV include control surfaces of a fixed-wing UAV and control surfaces of a rotary-wing UAV. The control surfaces of the fixed-wing UAV include at least one of the following: ailerons, elevators, rudders, flaps, spoilers, drag rudders, V-tail control surfaces, split aileron rudders, and elevators; the control surfaces of the rotary-wing UAV include hovering motors.

8. The control system for the unmanned aerial vehicle according to any one of claims 1-5, characterized in that, The control signals include at least one of the following: roll control signal, pitch control signal, yaw control signal, throttle control signal, brake control signal, flap control signal, spoiler control signal, and front wheel steering control signal.

9. The control system for the unmanned aerial vehicle according to any one of claims 1-5, characterized in that, The control system of the UAV also includes other bus devices, all of which are connected to the bus; the autopilot and the other bus devices communicate with each other through the bus; the bus is a CAN bus.

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