A segmented PID control method and system for vertical takeoff of a high-inertia, heavy-load multi-rotor UAV.

Abstract

This invention discloses a segmented PID control method and system for vertical takeoff of a high-inertia, heavy-load multi-rotor unmanned aerial vehicle (UAV), belonging to the field of UAV flight control technology. The method employs low-gain or semi-PID control during the weak support phase before takeoff to suppress motor chatter and fuselage vibration; after full takeoff, it automatically switches to full-gain PID parameters to ensure flight performance; and avoids control shocks through smooth parameter transitions. Simultaneously, it uses multiple sensors to jointly determine the flight status, improving switching accuracy. This invention effectively solves the problem of easy shaking and instability during the takeoff phase of high-inertia, heavy-load UAVs, improving takeoff safety and control stability.

Description

Technical Field

[0001] This invention relates to the field of multi-rotor unmanned aerial vehicle (UAV) flight control technology, specifically to a segmented PID control method and system for vertical takeoff of a high-inertia, heavy-load multi-rotor UAV. Background Technology

[0002] Multirotor drones, with their advantages of vertical takeoff and landing, stable hovering, and simple structure, are seeing increasing demand in heavy-load scenarios such as logistics transportation, fire rescue, and industrial inspection. Unlike conventional lightweight multirotor drones, high-inertia heavy-load multirotor drones (payload class of 5-50kg) have significantly greater fuselage rotational inertia and load inertia than lightweight drones, presenting unique control challenges during vertical takeoff. 1. Weak ground support phase: Before the drone takes off, the ground support reaction force and the friction between the fuselage and the ground will cause low-frequency disturbances to the flight control system. The large inertia of the fuselage has a stronger response lag to the control quantity. Conventional full-gain PID control will cause motor jitter, low-frequency oscillation of the fuselage, and even attitude tilting and rollover risks. 2. Takeoff switching shock: If conventional PID control is used directly, the control input changes suddenly after the UAV takes off completely, which will generate a dynamic shock to the large inertia fuselage, causing attitude jitter and altitude overshoot, seriously affecting takeoff safety; 3. Risk of status misjudgment: A single sensor (such as an altimeter) is susceptible to environmental interference and cannot accurately identify the drone's weak support / full take-off status, resulting in incorrect timing of PID parameter switching and causing control failure.

[0003] Traditional PID control methods are mostly designed for light and small UAVs and are not optimized for heavy-load scenarios with large inertia and weak ground support. They cannot solve the problems of jitter, impact and attitude instability during the vertical take-off of heavy-load UAVs. Therefore, there is an urgent need for a segmented PID control scheme that is suitable for heavy-load multi-rotor UAVs with large inertia. Summary of the Invention

[0004] The purpose of this invention is to provide a segmented PID control method and system for vertical takeoff of a large inertia heavy-load multi-rotor UAV, so as to solve the problems of motor chattering, control shock, and attitude instability of large inertia heavy-load multi-rotor UAVs mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A segmented PID control method for vertical takeoff of a high-inertia, heavy-load multi-rotor UAV includes the following steps: (1) Weak support stage control: When the UAV is in a weak support state before taking off, a low gain PID parameter or semi-PID control strategy is adopted to limit the control output amplitude of the attitude loop and altitude loop, and suppress the low frequency oscillation and motor chattering caused by the ground support reaction force and fuselage friction. (2) Takeoff phase control: Real-time acquisition of UAV altitude, motion status and power output data. After determining that the UAV has completely left the ground support and taken off stably, it automatically switches to full-gain full-speed PID control parameters to restore the standard dynamic response speed and anti-interference capability of the flight control system, and meet the requirements of normal hovering and maneuvering flight control. (3) Parameter smooth transition control: A continuous gradual transition logic is added between the weak ground support stage and the normal flight stage in the air to prevent the step change of PID parameters and avoid the problems of fuselage attitude shaking, power shock and instantaneous yaw tilt caused by sudden changes in control quantity.

[0006] Preferably, the condition for determining the weak support phase includes at least one of the following: the UAV's real-time ground clearance is lower than a preset height threshold; the average output speed of the motor does not reach the hovering reference speed; the accelerometer data identifies ground contact impact characteristics of the fuselage; and the barometer / radar altimeter data shows ground disturbance noise. This multi-sensor joint determination avoids parameter switching errors caused by misjudgments from a single sensor.

[0007] Preferably, the semi-PID control strategy specifically involves shutting down or deeply limiting the output of the PID derivative term (D term), synchronously reducing the gain parameters of the proportional term (P term) and integral term (I term), shielding high-frequency attitude correction actions, and retaining only the low-sensitivity basic attitude correction and slow altitude climb control capabilities, thereby suppressing motor vibration caused by ground disturbances at the source.

[0008] Preferably, the smooth transition logic adopts a linear interpolation gradual change or exponential gradual change filtering algorithm, using the flight altitude range and timing duration as trigger conditions to complete the continuous transition of the two sets of PID gain parameters in steps, so as to achieve shock-free switching of control quantities and avoid power impact on the large inertia fuselage.

[0009] Preferably, the method is adapted to heavy-load multi-rotor UAVs with high inertia. The payload of the heavy-load multi-rotor UAV is 5-50kg, and its fuselage moment of inertia is greater than that of conventional light and small multi-rotor UAVs, which can effectively solve the takeoff control problem in heavy-load scenarios.

[0010] The present invention also provides a flight control system for unmanned aerial vehicles, including an attitude and altitude controller, a flight status detection module, and a PID parameter switching module; The flight status detection module is used to collect drone altitude, motor speed, and inertial sensor data in real time, and accurately identify the drone's weak support state before takeoff and its fully airborne flight state. The PID parameter switching module is interconnected with the flight status detection module. It is used to call low-gain PID parameters or half-PID control parameters in the weak support state, and switch to full-gain full-speed PID control parameters in the fully airborne state, and execute smooth transition logic. The attitude and altitude controller, equipped with the aforementioned segmented PID control logic, completes attitude stabilization and vertical altitude closed-loop control of the large inertia heavy-load multi-rotor UAV based on the real-time parameters output by the PID parameter switching module.

[0011] Preferably, the control system is compatible with embedded flight control hardware platforms and can be applied to multi-rotor UAVs, vertical take-off and landing fixed-wing aircraft, and high-inertia heavy-load vertical take-off and landing equipment, with strong adaptability.

[0012] Preferably, the flight status detection module includes an altitude detection unit (barometer, radar altimeter), a rotation speed detection unit, and an inertial sensing unit (accelerometer, gyroscope). Each unit collects data synchronously and jointly determines the UAV status to avoid misjudgment by a single sensor.

[0013] Preferably, the PID parameter switching module has a built-in parameter storage unit that pre-stores PID parameter groups for the weak support stage and the takeoff stage, as well as smooth transition algorithm parameters. The parameters can be calibrated and adjusted according to the UAV's payload and environmental conditions, providing high flexibility.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention addresses the unique challenges of vertical takeoff for heavy-load multi-rotor UAVs with high inertia. It employs a segmented PID control strategy, utilizing low-gain control during the weak support phase to suppress chattering, full-gain control during ascent to ensure performance, and smooth transition logic to avoid impacts. Furthermore, it utilizes multi-sensor joint state determination to fundamentally solve the problems of motor chattering, attitude instability, and control impacts during the vertical takeoff of heavy-load UAVs. This significantly improves the safety and stability of heavy-load UAV takeoff and fills a technological gap in the takeoff control of heavy-load multi-rotor UAVs. Attached Figure Description

[0015] This application has no accompanying drawings, therefore the description of the drawings is omitted. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the technical solutions in the embodiments of the present invention. Example

[0017] This embodiment provides a segmented PID control method for vertical takeoff of a high-inertia, heavy-load multi-rotor UAV, the specific process of which is as follows: S1: Weak Support Phase Control: When the UAV is parked on the ground and in a weak support state before takeoff, the flight control system calls the pre-stored low-gain PID parameter group, shuts down the PID derivative term (D term) of the attitude loop and altitude loop, and simultaneously reduces the gain of the proportional term (P term) and integral term (I term) to 30%-50% of the normal parameters, limiting the control output amplitude, retaining only the basic attitude correction and slow altitude climb capabilities, and suppressing low-frequency oscillations and motor vibrations caused by ground support reaction force and friction. S2: Status determination: The flight status detection module collects the drone's altitude (barometer / radar altimeter), average motor speed, and accelerometer data in real time. When the three conditions of "ground clearance greater than 0.3m, motor speed reaching the hovering reference speed, and accelerometer showing no ground impact characteristics" are met, the drone is determined to have completely detached from ground support and entered a stable take-off state. S3: Smooth Transition Control: After the state switch is triggered, the system adopts a linear interpolation algorithm with a height range of 0.3m-1m as the transition range. Within 0.5s, the PID parameters are gradually changed from the low gain group to the full gain group to achieve a shockless switching of the control quantity and avoid attitude jitter caused by sudden parameter changes. S4: Ascent Phase Control: After the UAV completes the parameter transition, it adopts full-gain, full-speed PID control parameters to restore the standard dynamic response of the flight control system and meet the control requirements for hovering and maneuvering flight. Example

[0018] This embodiment provides a UAV flight control system for executing the segmented PID control method of Embodiment 1 above. The system architecture is as follows: 1. Flight Status Detection Module: Integrates an altitude detection unit (barometer, radar altimeter), a rotation speed detection unit, and an inertial sensing unit (accelerometer, gyroscope). Each unit collects data synchronously at a frequency of 100Hz, and the UAV status is determined by combining multiple conditions. 2. PID Parameter Switching Module: Built-in parameter storage unit, pre-stores PID parameter groups for the weak support phase and takeoff phase, as well as linear interpolation transition algorithm parameters. Based on the output of the flight status detection module, it switches PID parameters in real time and performs a smooth transition. 3. Attitude and Altitude Controller: Equipped with segmented PID control logic, it completes closed-loop control of the UAV's attitude angle and altitude based on real-time PID parameters, outputs motor control commands, and achieves stable control of the vertical takeoff phase of a high-inertia, heavy-load multi-rotor UAV.

[0019] This system can be directly integrated into existing embedded flight control hardware (such as STM32 and PX4 flight controllers) without additional hardware modifications. It is compatible with 5-50kg class heavy-duty multi-rotor drones with high inertia, and can effectively improve the safety and stability of vertical take-off of heavy-duty drones.

Claims

1. A segmented PID control method and system for vertical takeoff of a high-inertia, heavy-load multi-rotor unmanned aerial vehicle (UAV), characterized in that, Includes the following steps: (1) Weak support phase control: When the UAV is in a weak support state before taking off, a low gain PID parameter or semi-PID control strategy is adopted to limit the control output amplitude of the attitude loop and altitude loop, and suppress the low frequency oscillation and motor jitter caused by the ground support reaction force and fuselage friction. (2) Ascent phase control: Real-time acquisition of UAV altitude, motion state and power output data, and after determining that the UAV has completely left the ground support and taken off stably, it automatically switches to full gain full speed PID control parameters to restore the standard dynamic response speed and anti-interference capability of the flight control system, and meet the normal hovering and maneuvering flight control requirements. (3) Parameter smooth transition control: Between the weak support phase and the normal flight phase in the air, a continuous gradual transition logic is added to prevent the step change of PID parameters and avoid fuselage attitude jitter, power shock and instantaneous yaw tilt caused by sudden changes in control quantity.

2. The method of claim 1, wherein: The conditions for determining the state of the weak support stage include at least one of the following: the real-time altitude of the UAV is lower than the preset altitude threshold, the average output speed of the motor does not reach the reference speed for hovering in the air, the accelerometer data identifies ground contact impact characteristics of the fuselage, and the barometer / radar altimeter data contains ground disturbance noise.

3. The method of claim 1, wherein: The semi-PID control strategy specifically involves disabling or deeply limiting the output of the PID derivative term (D term), simultaneously reducing the gain parameters of the proportional term (P term) and integral term (I term), shielding high-frequency attitude correction actions, and retaining only the low-sensitivity basic attitude correction and slow altitude climb control capabilities.

4. The method of claim 1, wherein: The smooth transition logic employs a linear interpolation gradual change or exponential gradual change filtering algorithm, using flight altitude range and timing duration as trigger conditions to complete the continuous transition of two sets of PID gain parameters in steps, achieving shock-free switching of control quantities.

5. The method of claim 1, wherein: The method is adapted to heavy-duty multi-rotor drones with high inertia, which have a payload of 5-50 kg and a fuselage moment of inertia greater than that of conventional light and small multi-rotor drones.

6. A drone flight control system, characterized in that, The system includes an attitude and altitude controller, a flight status detection module, and a PID parameter switching module. The flight status detection module is used to collect real-time data on the UAV's altitude, motor speed, and inertial sensor speed to accurately identify the UAV's weak support state before takeoff and its fully airborne flight state. The PID parameter switching module is interconnected with the flight status detection module and is used to call low-gain PID parameters or half-PID control parameters in the weak support state, and switch to full-gain, full-speed PID control parameters in the fully airborne state, executing the smooth transition logic described in claim 4. The attitude and altitude controller is equipped with the segmented PID control logic described in any one of claims 1-5, and completes attitude stabilization and vertical altitude closed-loop control of the high-inertia, heavy-load multi-rotor UAV based on the real-time parameters output by the PID parameter switching module.

7. The system of claim 6, wherein: This control system is compatible with embedded flight control hardware platforms and can be applied to multi-rotor UAVs, vertical take-off and landing fixed-wing aircraft, and high-inertia heavy-load vertical take-off and landing equipment.

8. The system of claim 6, wherein: The flight status detection module includes an altitude detection unit (barometer, radar altimeter), a rotation speed detection unit, and an inertial sensing unit (accelerometer, gyroscope). Each unit collects data synchronously and jointly determines the UAV status to avoid misjudgment by a single sensor.

9. The system of claim 6, wherein: The PID parameter switching module has a built-in parameter storage unit that pre-stores PID parameter sets for the weak support stage and the takeoff stage, as well as smooth transition algorithm parameters, and can perform parameter calibration and adjustment according to the UAV's payload and environmental conditions.