Operation arm for intelligent operation of unmanned aerial vehicle, control method and motion control system

Abstract

The invention relates to the technical field of unmanned aerial vehicle operation arm control, and discloses an operation arm for intelligent operation of an unmanned aerial vehicle, a control method and a motion control system. The stable control method of the operation arm for intelligent operation of the unmanned aerial vehicle has the following advantages and effects that the disturbance problem existing at the tail end of the operation arm is solved, and the stability of an operation arm system is guaranteed. Firstly, system kinematics and dynamics are derived in a mathematical model, and influences of interference, system nonlinearity and hardware parameterization are considered. Secondly, an observer is proposed to estimate unmeasured perturbations. And then, a full-state feedback controller is designed based on an inversion process, so that the performance of the operation arm system is ensured. According to the method, the influence of system delay is reduced to a certain extent, and meanwhile, a good motion control effect can be ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of unmanned aerial vehicle operating arm control, and in particular relates to an operating arm and a control method and a motion control system for unmanned aerial vehicle intelligent operation. Background Art

[0002] Two-axis gimbal mechanisms are widely used in practical applications where the end effector needs to be stabilized or steered to follow a desired direction. On UAVs, the motion of the end effector is severely affected by the intentional manipulation and unintentional motion of the UAV. The first and fundamental goal of controlling the gimbal system is to keep the end effector stable, while the complexity of the gimbal system dynamics and other unknown disturbances make these tasks challenging.

[0003] The gimbal itself has a simple structure, but its dynamics are complex with nonlinear factors, coupling and interference. In addition, the actual gimbal system and its components do not operate ideally, which significantly affects the performance of the control system. The saturation of the actuator, the gyroscope output parameterization and the communication network may be one of the actual factors that lead to the deterioration of performance. However, although most of the developed techniques have been proven to be effective for state delay systems, control input delay systems are more complex and difficult to handle. Therefore, it is necessary to design an effective control system to achieve robust stability and good tracking performance. Summary of the invention

[0004] The purpose of the present invention is to provide an operating arm and a control method and a motion control system for intelligent operation of unmanned aerial vehicles, which are used to solve the disturbance problem at the end of the operating arm to ensure system stability, reduce the impact of system delay, and ensure good motion control effect.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions: an operating arm for intelligent operation of a drone, comprising a jet generating mechanism, the jet generating mechanism comprising a main switching valve, a piston located in the main switching valve, a first pressure gas tank, a second pressure gas tank, a first one-way quick exhaust valve, a second one-way block exhaust valve, and a piston rod connected to the piston, a valve cavity is formed in the main switching valve, a water inlet is formed in the middle of the valve cavity, the piston divides the valve cavity into a first valve cavity and a second valve cavity, the first pressure tank and the first one-way quick exhaust valve are connected to the first valve cavity, the second pressure tank and the second quick exhaust valve are connected to the second pressure tank, when the piston moves toward the first valve cavity, the piston rod drives the first one-way quick exhaust valve to close and the second one-way quick exhaust valve to open, when the piston moves toward the second valve cavity, the piston rod drives the second one-way quick exhaust valve to close and the first one-way quick exhaust valve to open.

[0006] The present invention is further configured to include a YAW axis drive motor, a PITCH axis drive motor, and a dual-axis gimbal mechanism, wherein the dual-axis gimbal mechanism includes an outer gimbal for driving pitch motion and an inner gimbal for driving tilt motion.

[0007] Another object of the present invention is to provide a control method for an operating arm of a drone for intelligent operation, comprising the following steps:

[0008] S1, based on the dynamic characteristics of the jet generating mechanism and combined with the dynamic characteristics of the operating arm, the structure and dynamic characteristics of the arm-mounted jet generating mechanism are tuned to construct an operating arm for UAV intelligent operation;

[0009] S2, based on the structural characteristics of the manipulator, a kinematic model of a two-axis gimbal manipulator based on a reference coordinate system is constructed to describe the mapping relationship between the rate of change of each Euler angle of the manipulator and the angular velocity of the joint rotation. By applying the Euler rigid body dynamics equation and considering the signal transmission delay, the system dynamics equation is derived from the torque relationship of the inner and outer universal joints;

[0010] S3, consider the external disturbance of the system, assume it is bounded and differentiable, regard it as the extended state of the system, design the system extended state observer, obtain the observation error equation, and set the observer pole within its bandwidth to ensure convergence;

[0011] S4, designs a pseudo control quantity for the Euler angular rate, and designs a nonlinear controller based on the inversion technique and the improved extended state observer to output the speed control quantity under delay.

[0012] The present invention is further configured as follows: in step S2, the origin of the reference coordinate system is at the rotation center of the universal mount, and the kinematic equation of the system is as follows:

[0013]

[0014] Where ω=[ω x ω y ω z ] T represents the angular velocity vector of the platform at the end of the manipulator, represents the angular velocity vector of the UAV base platform, α is the rotation angle between the inner gimbal and the outer gimbal along the roll axis, β is the rotation angle between the outer gimbal and the base platform along the yaw axis, ω α and ω β represent their angular velocities respectively.

[0015] The present invention is further configured such that the coordinates of the inner gimbal end can be described by three Euler angles as follows:

[0016] represents the rotation angle around the pitch axis x of the inner gimbal moving frame;

[0017] represents the rotation angle around the roll axis y of the inner gimbal mobile frame;

[0018] represents the rotation angle around the yaw axis z of the inner gimbal fixed frame;

[0019] By taking the angular velocity of each Euler angle with respect to the coordinate system, the relationship between the angular velocity of the manipulator and the rate of change of the Euler angle is obtained as follows:

[0020]

[0021] The present invention is further configured as follows: in step S2, the system dynamics is derived from the torque relationship of the inner and outer universal joints by applying the Euler rigid body dynamics equation. Considering the time lag from the sensor to the controller and from the controller to the driver, the system behaves as an input delay system, in which the actual control signal acting on the actuator at a specific time is a delayed version calculated by the controller. Assuming the delay time is h, the dynamic model of the system can be written in the following form:

[0022]

[0023] Where the diagonal matrix A represents the relationship between the angular velocity and the Euler angular velocity, and B represents The equivalent disturbance at time , u c represents the speed control quantity output by the controller under the condition of delay, C and D represent the system parameter matrix, k T represents the unpredictable disturbance vector;

[0024] The matrices A and B can be described as follows:

[0025]

[0026] The present invention is further configured as follows: in step S3, the expansion state of the system is expressed in the following form:

[0027]

[0028] In the formula C e =[OCO] T , K e =[OOI] T , O is the zero matrix, and I is the identity matrix.

[0029] The present invention is further configured as follows: in step S3, the observer is designed as follows:

[0030]

[0031] The observed state variable Observer gain K es =[K1K2 K3] T , the observation error can be written as follows:

[0032]

[0033] The error equation can be written as:

[0034]

[0035] The gains of the designed observer are chosen as follows:

[0036]

[0037] Where ψ=diag{ψ x ,ψ y}, the elements in the matrix represent the observer bandwidth of the pitch and roll channels respectively.

[0038] The present invention is further configured as follows: in step S4, a control error term is defined:

[0039]

[0040] Where ξ is the pseudo control for stabilizing the Euler angular velocity. The pseudo control and control law at the current time are designed as follows:

[0041]

[0042] Where σ and μ are positive definite diagonal matrices, and k ω is the gain parameter, and λ ω is a positive gain vector, [sgn(e i )] represents a diagonal matrix where each element is a sign function of the corresponding row in the error vector.

[0043] Another object of the present invention is to provide a motion control system for an operating arm of an unmanned aerial vehicle for intelligent operation, comprising a processor, wherein the processor is used to execute the control method for the operating arm of an unmanned aerial vehicle for intelligent operation.

[0044] The beneficial effects of the present invention are as follows: the present invention provides a stable control method for an operating arm for intelligent operation of unmanned aerial vehicles, which is used to solve the disturbance problem at the end of the operating arm to ensure the stability of the operating arm system. First, the system kinematics and dynamics are derived in a mathematical model, in which the influence of interference, system nonlinearity and hardware parameterization are considered. Secondly, an observer is proposed to estimate unmeasured disturbances. Then, a full-state feedback controller is designed based on the inversion process to ensure the performance of the operating arm system. The present invention reduces the influence of system delay to a certain extent, while ensuring a good motion control effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the pulse jet generating mechanism of the present invention.

[0046] Figure 2 is a top view of the manipulator system of the present invention.

[0047] Figure 3 It is a front view of the operating arm system of the present invention.

[0048] Figure 4 It is a controller design block diagram of the present invention.

[0049] In the figure, 1, water inlet; 2, first pressure gas tank; 3, piston; 31, piston rod; 4, second pressure gas tank; 5, first one-way quick exhaust valve; 6, water outlet; 7, second one-way quick exhaust valve; 8, main switching valve; 81, first valve chamber; 82, second valve chamber; 9, YAW axis drive motor; 10, PITCH axis drive motor. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] The control method of the operating arm for the intelligent operation of the unmanned aerial vehicle comprises the following steps:

[0052] S1, based on the dynamic characteristics of the jet generating mechanism and combined with the dynamic characteristics of the operating arm, the structure and dynamic characteristics of the arm-mounted jet generating mechanism are tuned to construct an operating arm for intelligent operation of UAVs.

[0053] Specifically, the operating arm used for the intelligent operation of the UAV includes a jet generating mechanism, a YAW axis driving motor and a PITCH axis driving motor, and a dual-axis universal joint mechanism. The dual-axis universal joint mechanism includes an outer universal joint for driving the pitch motion and an inner universal joint for driving the tilt motion.

[0054] The jet generating mechanism includes a main switching valve, a piston located in the main switching valve, a first pressure gas tank, a second pressure gas tank, a first one-way quick exhaust valve, a second one-way block exhaust valve, and a piston rod connected to the piston. A valve cavity is formed in the main switching valve, and a water inlet is formed in the middle of the valve cavity. The piston divides the valve cavity into a first valve cavity and a second valve cavity. The first pressure tank and the first one-way quick exhaust valve are connected to the first valve cavity, and the second pressure tank and the second quick exhaust valve are connected to the second pressure tank. When the piston moves toward the first valve cavity, the piston rod drives the first one-way quick exhaust valve to close and the second one-way quick exhaust valve to open. When the piston moves toward the second valve cavity, the piston rod drives the second one-way quick exhaust valve to close and the first one-way quick exhaust valve to open.

[0055] When the jet generating mechanism is in the Figure 1 In the state shown, the first one-way quick exhaust valve is closed under the incoming flow pressure, and the second one-way quick exhaust valve is opened under the action of the piston rod connected to the piston of the main switching valve. The pressure of the first valve chamber of the main switching valve is greater than the pressure of the second valve chamber, and the piston moves downward. Then, the piston rod connected to the piston of the main switching valve will be disengaged due to the limited stroke of the second one-way quick exhaust valve, and the lower valve chamber is closed. When closed, the pressure in the chamber is the outlet pressure. Since the outlet pressure is less than the incoming flow pressure, the piston of the main switching valve will continue to move downward, and the second pressure gas tank will continue to compress.

[0056] As the piston of the main switching valve moves downward, the piston rod connected to it will activate the first one-way quick exhaust valve, the pressure in the first valve chamber will be released instantly, the first pressure gas tank will relax, and the piston of the main switching valve will move upward until the piston of the main switching valve passes the midpoint. At this time, the second quick exhaust valve has not been triggered, and the piston will continue to move upward under the incoming flow pressure until the first quick exhaust valve is closed and the second quick exhaust valve is opened, thus completing a working cycle.

[0057] The pulse water jet generating mechanism of the present invention uses the pressure and flow of the water source as the power, and utilizes the self-excited pressure relief principle of the hydrodynamic self-excited quick exhaust valve mechanism to transform the continuous incoming flow into a pulse jet.

[0058] The basic dynamic characteristics of the pulsed water jet mechanism are constructed, including the time-domain variation characteristics of the center of mass, inertia, momentum, etc. Based on the above characteristics, the geometric characteristics and mass distribution of the pulsed water jet mechanism and its mounting frame can be tuned, and combined with the dynamic characteristics of the dual-axis gimbal, a lightweight operating arm system for UAV intelligent operations based on the dual-axis gimbal mechanism can be constructed.

[0059] S2, based on the structural characteristics of the manipulator, constructs the kinematic model of a two-axis gimbaled manipulator based on the reference coordinate system, describes the mapping relationship between the rate of change of each Euler angle of the manipulator and the angular velocity of the joint rotation, and derives the system dynamics equation from the torque relationship of the inner and outer universal joints by applying the Euler rigid body dynamics equation and considering the signal transmission delay.

[0060] The dual-axis gimbal manipulator system considered in the present invention consists of an outer gimbal that drives the pitch motion and an inner gimbal that drives the tilt motion. The origins of all coordinate systems coincide at the rotation center of the gimbal, giving the kinematics of the system as follows:

[0061]

[0062] Where ω=[ω x ω y ω z ] T represents the angular velocity vector of the platform at the end of the manipulator, Represents the angular velocity vector of the UAV base platform. α is the rotation angle between the inner gimbal and the outer gimbal along the roll axis, and β is the rotation angle between the outer gimbal and the base platform along the yaw axis. ω α and ω β represent their angular velocities respectively.

[0063] The coordinates of the inner gimbal end can be described by three Euler angles as follows:

[0064] Represents the rotation angle about the pitch axis x of the inner gimbal moving frame.

[0065] Represents the rotation angle about the roll axis y of the inner gimbal moving frame.

[0066] Represents the rotation angle about the yaw axis z of the inner gimbal fixed frame.

[0067] By taking the angular velocity of each Euler angle with respect to the coordinate system, the relationship between the angular velocity of the manipulator and the rate of change of the Euler angle is obtained as follows:

[0068]

[0069] Next, the Euler rigid body dynamics equations are applied to derive the system dynamics from the torque relationship of the inner and outer universal joints. Considering the time lag from the sensor to the controller and from the controller to the actuator, the system behaves as an input delay system, where the actual control signal acting on the actuator at a specific time is a delayed version of the controller calculation. Let the delay time be h, and the dynamic model of the system can be written as follows:

[0070]

[0071] Where the diagonal matrix A represents the relationship between the angular velocity and the Euler angular velocity, and B represents The equivalent disturbance at time , u c represents the speed control quantity output by the controller under the condition of delay, C and D represent the system parameter matrix, k T represents the unpredictable disturbance vector.

[0072] The matrices A and B can be described as follows:

[0073]

[0074] S3, consider the external interference of the system, assume it is bounded and differentiable, regard it as the extended state of the system, design the system extended state observer, obtain the observation error equation, and set the observer pole within its bandwidth to ensure convergence.

[0075] Specifically, the extended state observer is then designed, assuming that the disturbance is bounded and differentiable, and is regarded as an extended state of the system and expressed in the following form:

[0076]

[0077] In the formula C e =[OCO] T , K e =[OOI] T , O is the zero matrix, and I is the identity matrix.

[0078] The observer is designed as follows:

[0079]

[0080] The observed state variable Observer gain K es =[K1K2 K3] T , the observation error can be written as follows:

[0081]

[0082] The error equation can be written as:

[0083]

[0084] In order to maintain the convergence of the error, the observer gain setting should make the observer poles within its bandwidth. The gain selection of the designed observer is as follows:

[0085]

[0086] Where ψ=diag{ψ x ,ψ y}, the elements in the matrix represent the observer bandwidth of the pitch and roll channels respectively.

[0087] S4, designs a pseudo control quantity for the Euler angular rate, and designs a nonlinear controller based on the inversion technique and the improved extended state observer to output the speed control quantity under delay.

[0088] Specifically, define the control error term:

[0089]

[0090] Where ξ is the pseudo control of the stable Euler angular velocity. The pseudo control and control law at the current time are designed as follows:

[0091]

[0092] Where σ and μ are positive definite diagonal matrices, and k ω is the gain parameter, and λ ω is a positive gain vector, [sgn(e i )] represents a diagonal matrix where each element is a sign function of the corresponding row in the error vector. The controller design block diagram is shown in Figure 4 shown.

[0093] A motion control system for an operating arm of an unmanned aerial vehicle for intelligent operation includes a processor, and the processor is used to execute the above-mentioned control method for the operating arm of an unmanned aerial vehicle for intelligent operation.

Claims

1. An operating arm for intelligent operation of unmanned aerial vehicles, characterized by: The invention comprises a jet generating mechanism, which comprises a main switching valve, a piston located in the main switching valve, a first pressure gas tank, a second pressure gas tank, a first one-way quick exhaust valve, a second one-way block exhaust valve, and a piston rod connected to the piston. A valve cavity is formed in the main switching valve, a water inlet is formed in the middle of the valve cavity, the piston divides the valve cavity into a first valve cavity and a second valve cavity, the first pressure tank and the first one-way quick exhaust valve are connected to the first valve cavity, the second pressure tank and the second quick exhaust valve are connected to the second pressure tank, when the piston moves toward the first valve cavity, the piston rod drives the first one-way quick exhaust valve to close and the second one-way quick exhaust valve to open, and when the piston moves toward the second valve cavity, the piston rod drives the second one-way quick exhaust valve to close and the first one-way quick exhaust valve to open.

2. The operating arm for intelligent operation of unmanned aerial vehicle according to claim 1, characterized in that: It also includes a YAW axis driving motor, a PITCH axis driving motor, and a dual-axis gimbal mechanism, wherein the dual-axis gimbal mechanism includes an outer gimbal for driving pitch motion and an inner gimbal for driving tilt motion.

3. A control method for an operating arm of an unmanned aerial vehicle for intelligent operation, characterized in that: The following steps are included: S1, based on the dynamic characteristics of the jet generating mechanism and combined with the dynamic characteristics of the operating arm, the structure and dynamic characteristics of the arm-mounted jet generating mechanism are tuned to construct an operating arm for UAV intelligent operation; S2, based on the structural characteristics of the manipulator, a kinematic model of a two-axis gimbal manipulator based on a reference coordinate system is constructed to describe the mapping relationship between the rate of change of each Euler angle of the manipulator and the angular velocity of the joint rotation. By applying the Euler rigid body dynamics equation and considering the signal transmission delay, the system dynamics equation is derived from the torque relationship of the inner and outer universal joints; S3, consider the external disturbance of the system, assume it is bounded and differentiable, regard it as the extended state of the system, design the system extended state observer, obtain the observation error equation, and set the observer pole within its bandwidth to ensure convergence; S4, designs a pseudo control quantity for the Euler angular rate, and designs a nonlinear controller based on the inversion technique and the improved extended state observer to output the speed control quantity under delay.

4. The control method for the operating arm of a drone for intelligent operation according to claim 3, characterized in that: In step S2, the origin of the reference coordinate system is at the rotation center of the gimbal, and the kinematic equation of the system is as follows: Where ω=[ω x ω y ω z ] T represents the angular velocity vector of the platform at the end of the manipulator, represents the angular velocity vector of the UAV base platform, α is the rotation angle between the inner gimbal and the outer gimbal along the roll axis, β is the rotation angle between the outer gimbal and the base platform along the yaw axis, ω α and ω β represent their angular velocities respectively.

5. The control method for the operating arm of a drone for intelligent operation according to claim 4, characterized in that: The coordinates of the inner gimbal end can be described by three Euler angles as follows: represents the rotation angle around the pitch axis x of the inner gimbal moving frame; represents the rotation angle around the roll axis y of the inner gimbal mobile frame; represents the rotation angle around the yaw axis z of the inner gimbal fixed frame; By taking the angular velocity of each Euler angle with respect to the coordinate system, the relationship between the angular velocity of the manipulator and the rate of change of the Euler angle is obtained as follows:

6. The control method for the operating arm of a drone for intelligent operation according to claim 5, characterized in that: In step S2, the Euler rigid body dynamics equation is applied to derive the system dynamics from the torque relationship between the inner and outer universal joints. Considering the time lag from the sensor to the controller and from the controller to the driver, the system behaves as an input delay system, where the actual control signal acting on the actuator at a specific time is a delayed version calculated by the controller. Let the delay time be h. The dynamic model of the system can be written as follows: Where the diagonal matrix A represents the relationship between the angular velocity and the Euler angular velocity, and B represents The equivalent disturbance at time , u c represents the speed control quantity output by the controller under the condition of delay, C and D represent the system parameter matrix, k T represents the unpredictable disturbance vector; The matrices A and B can be described as follows:

7. The control method for the operating arm of a drone for intelligent operation according to claim 3, characterized in that: In step S3, the expansion state of the system is expressed in the following form: In the formula C e =[OCO] T , K e =[OOI] T , O is the zero matrix, and I is the identity matrix.

8. The control method for the operating arm of a drone for intelligent operation according to claim 3, characterized in that: In step S3, the observer is designed as follows: The observed state variable Observer gain K es =[K1 K2 K3] T , the observation error can be written as follows: The error equation can be written as: The gains of the designed observer are chosen as follows: Where ψ=diag{ψ x ,ψ y }, the elements in the matrix represent the observer bandwidth of the pitch and roll channels respectively.

9. The control method for the operating arm of a drone for intelligent operation according to claim 3, characterized in that: In step S4, the control error term is defined: Where ξ is the pseudo control for stabilizing the Euler angular velocity. The pseudo control and control law at the current time are designed as follows: Where σ and μ are positive definite diagonal matrices, and k ω is the gain parameter, and λ ω is a positive gain vector, [sgn(e i )] represents a diagonal matrix where each element is a sign function of the corresponding row in the error vector.

10. A motion control system for an operating arm of a drone for intelligent operation, characterized in that: It includes a processor, which is used to execute the control method of the operating arm for intelligent operation of a drone as described in any one of claims 3-9.

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