A swing-type low-frequency active dynamic vibration absorption device and its control system and method

Abstract

The present invention relates to the field of robotic arm control technology, and more specifically to a swing-type low-frequency active dynamic vibration absorption device and its control system and method. The device comprises a swing arm mechanism, a rotating mechanism, and a rotating disk, wherein the swing arm mechanism comprises a pendulum, a swing rod, a swing arm motor, and a motor bracket. The swing arm mechanism comprises a first swing arm mechanism and a second swing arm mechanism, which are symmetrically arranged at the upper end of the rotating disk. The swing arm motor is located at the upper end of the motor bracket and fixedly connected to the motor bracket. The rotating disk is located at the lower end of the motor bracket and fixedly connected to the motor bracket. The pendulum is flange-connected to the swing rod, and the swing rod is connected to the motor shaft of the swing arm motor. The swing arm mechanism also comprises a support device, which is used to provide support force for the motor shaft. The rotating mechanism comprises a rotating motor, a rigid support structure, and a chassis. The motor shaft of the rotating motor is fixedly connected to the rotating disk, and the rigid support structure connects the rotating disk and the chassis.

Description

Technical Field

[0001] The present invention relates to the technical field of robotic arm control, and in particular to a swing-type low-frequency active dynamic vibration absorbing device and a control system and method thereof. Background Art

[0002] Space manipulators typically utilize a slender rod design, with joints equipped with harmonic reducers and joint position sensors. The introduction of these flexible structures presents a key challenge: during motion or when subjected to external disturbances, the flexible structure can cause the manipulator to vibrate. Space manipulators can be categorized by their degree of flexibility: flexible joints with rigid links, rigid joints with flexible links, and flexible joints with flexible links. Currently, even after implementing joint motion control algorithms to suppress vibration in pre-research space manipulators, low-frequency vibrations still persist, severely impacting control accuracy and operational refinement. Vibration suppression for manipulators primarily involves joint motion control and dynamic vibration absorbers. Joint motion control is ineffective in suppressing low-frequency residual vibrations in manipulators, while dynamic vibration absorbers typically employ linear dynamic vibration absorbers. However, traditional linear dynamic vibration absorbers, when used to suppress low-frequency vibrations in space manipulators, suffer from the problem of long travel. Summary of the Invention

[0003] The technical problem solved by the present invention is to provide a swing-type low-frequency active dynamic vibration absorption device and its control system and method, which can reduce the impact of low-frequency vibration at the end of a robotic arm.

[0004] The basic solution provided by the present invention is: a swing-type low-frequency active dynamic vibration absorption device and its control system, including a swing arm mechanism, a rotating mechanism and a rotating disk, the swing arm mechanism including a pendulum, a swing rod, a swing arm motor, and a motor bracket, the swing arm mechanism including a first swing arm mechanism and a second swing arm mechanism, which are symmetrically arranged on the upper end of the rotating disk, the swing arm motor is located at the upper end of the motor bracket and fixedly connected to the motor bracket, the rotating disk is located at the lower end of the motor bracket and fixedly connected to the motor bracket, the pendulum is connected to the swing rod flange, the swing rod is connected to the motor shaft of the swing arm motor, and the swing arm mechanism also includes a support device, which is used to provide support force for the motor shaft;

[0005] The rotating mechanism includes a rotating motor, a rigid support structure, and a chassis. The motor shaft of the rotating motor is fixedly connected to the rotating disk. The rigid support structure connects the rotating disk and the chassis. The rotating mechanism is used to rotate in the vibration direction of the end of the flexible arm.

[0006] It also includes a control module, which includes a controller and a gyroscope. The controller is connected to the gyroscope, and the controller is electrically connected to the swing arm motor and the rotary motor. The gyroscope is used to obtain the acceleration values ​​of the end of the flexible arm in the X direction and the Y direction and send them to the controller. The controller calculates the rotation speed of the swing arm mechanism based on the acceleration values ​​of the end of the flexible arm in the X direction and the Y direction, and controls the swing arm motor to operate at this rotation speed.

[0007] Furthermore, the supporting device includes a bearing bracket, a connecting plate, a sleeve, a deep groove ball bearing and a bearing lower bracket. The motor shaft of the swing arm motor is provided with a sleeve. The deep groove ball bearing is arranged on the bearing bracket and cooperates with the sleeve. The lower end of the bearing lower bracket is fixedly connected to the rotating disk, and the upper end is connected to the bearing bracket through a connecting plate.

[0008] Furthermore, the rigid support structure includes a fixing frame, a bearing frame, and an angular contact bearing. The sleeve cooperates with the motor shaft of the rotating motor, the bearing frame cooperates with the sleeve, the upper end of the fixing frame is fixedly connected to the lower end of the bearing frame, and the lower end of the fixing frame is fixedly connected to the chassis.

[0009] Furthermore, the pendulum is provided with a pendulum cover, the pendulum cover is processed with an annular groove, and a detachable rubber sealing strip is provided in the annular groove.

[0010] Furthermore, it also includes a top plate, which is located above the swing arm mechanism, and an electric slider is provided below the top plate. The rotating shaft of the electric slider is fixedly connected to the rotating plate, and the controller is electrically connected to the swing arm motor and the rotating motor through the electric slider.

[0011] The principle and advantage of the present invention lies in that the swing ball type dynamic vibration absorber structurally includes a rotating mechanism, a swing arm mechanism and other auxiliary structures, and the software includes a control system of an embedded operating system.

[0012] The swing mechanism is primarily responsible for generating force to suppress vibration at the end of the robotic arm, while the rotation mechanism is responsible for adjusting the direction of the force generated by the swing mechanism, ensuring that the force direction of the swing mechanism always aligns with the vibration direction of the robotic arm. The auxiliary mechanism primarily includes components such as slip rings, which ensure 360° free rotation of the rotation mechanism. The control system program primarily incorporates a cosine-modulated active disturbance rejection control algorithm based on a linear active disturbance rejection algorithm, which enables the designed swing ball dynamic vibration absorber to operate effectively.

[0013] The tracking-differentiator is moved from the input to the output. On the one hand, this is because this is a vibration suppression algorithm and the expected signal is 0, so a tracking-differentiator is not needed. On the other hand, the modulated cosine output has a step value, and the tracking-differentiator can smoothly handle this sudden change.

[0014] Traditional nonlinear ADRC requires adjusting 12 parameters, while linear ADRC requires adjusting 6 parameters. However, after pole configuration, linear ADRC only requires adjusting 3 parameters, allowing it to be quickly deployed in engineering applications.

[0015] In order to reduce the impact of the motor, a speed output modulation method is proposed. After simulation and experimental verification, this method can greatly reduce the impact of the motor and provide a basis for vibration suppression.

[0016] The controller inherits the model-independence characteristics of the traditional classic ADRC, which enables the dynamic vibration absorber to suppress the vibration of the flexible arm without relying on the mathematical model. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a structural schematic diagram of a swing arm mechanism in an embodiment of a swing-type low-frequency active dynamic vibration absorbing device and its control system according to the present invention;

[0018] Figure 2 This is a structural schematic diagram of a rotating mechanism in an embodiment of a swing-type low-frequency active dynamic vibration absorbing device and its control system of the present invention;

[0019] Figure 3 This is a structural schematic diagram of an embodiment of a swing-type low-frequency active dynamic vibration absorbing device and its control system according to the present invention;

[0020] Figure 4 This is the control block diagram of a traditional active disturbance rejection controller controlling a swing-type dynamic vibration absorber.

[0021] Figure 5 This is a control block diagram of a swing-type low-frequency active dynamic vibration absorber and its control system embodiment of the present invention, which uses a cosine modulation active disturbance rejection controller to control a swing dynamic vibration absorber;

[0022] Figure 6 This is a circuit connection diagram of a swing ball type dynamic vibration absorber in an embodiment of a swing type low frequency active dynamic vibration absorbing device and its control system of the present invention;

[0023] Figure 7 This is a logic block diagram between the peripheral devices and the main control board of a swing ball-type dynamic vibration absorber in an embodiment of a swing-type low-frequency active dynamic vibration absorption device and its control system of the present invention;

[0024] Figure 8 This is a schematic diagram showing the principle of vibration suppression achieved by a swing arm mechanism in an embodiment of a swing-type low-frequency active dynamic vibration absorbing device and its control system according to the present invention. DETAILED DESCRIPTION

[0025] The following is further described in detail through specific implementation methods:

[0026] The symbols in the drawings of the specification include: pendulum 1, pendulum cover 2, pendulum connecting flange 3, bearing bracket 4, connecting plate 5, bushing 6, deep groove ball bearing 7, rocker arm connecting flange 8, rocker arm 9, rocker arm motor 10, motor bracket 11, bearing lower bracket 12, rotating disk 13, motor shaft 14, bushing 15, motor shaft 16, angular contact bearing 17, bearing end cover 18, bearing bracket 19, fixing bracket 20, chassis 21, motor bracket 22, rotating motor 23, bushing 24, electric slip ring 25, electric slip ring rotating shaft 26, support frame 27, top plate 28.

[0027] The embodiment is basically as shown in the attached Figure 1 As shown:

[0028] A swing-type, low-frequency active dynamic vibration absorption device and its control system include a swing arm mechanism, a rotating mechanism, and a rotating disk 13. The swing arm mechanism includes a pendulum 1, a pendulum rod 8, a swing arm motor 10, and a motor bracket 11. The pendulum cover 2 is machined with an annular groove into which a rubber sealing strip can be inserted. This allows the interior of the pendulum 1 to accommodate not only solid materials but also liquids to be injected to enhance the damping effect. However, materials can only be added statically; they cannot be changed during operation. The pendulum 1 and pendulum cover 2 are connected to the pendulum rod 9 via threaded jackscrew holes in the pendulum connecting flange 3. The pendulum rod connecting flange 8 and the pendulum rod 9 are also fixedly connected via jackscrew holes. A bolt and nut connection at the rear end provides preload force to clamp the motor shaft 14. To prevent the centrifugal force of the pendulum from directly applying a tilting torque to the motor shaft 14 and thereby damaging the brushless motor 10, a support assembly consisting of a bearing bracket 4, a connecting plate 5, a bushing 6, a deep groove ball bearing 7, and a lower bearing bracket 12 is designed. These components provide support for the motor shaft 14. The brushless motor 10, motor bracket 11, and rotating disk 13 are securely connected by screws. To avoid force disturbances caused by uneven mass distribution, the brushless motor 10 and its associated pendulum components are designed with a symmetrical distribution. Regarding material selection, the pendulum arm 9 and motor shaft 14 require certain bending and torsional strength, so 45 steel is used. The connecting piece 5 securely connects the two brackets and also requires a certain degree of bending strength, so Q235 carbon structural steel is selected. Other components are made of aluminum alloy 6063 for weight reduction.

[0029] like Figure 2 As shown, the rotating mechanism includes a rotating motor 23, a rigid support structure and a chassis 21. The motor shaft 16 of the rotating motor 23 is fixedly connected to the rotating disk 13. The rigid support structure connects the rotating disk 13 and the chassis 21. The rotating mechanism is used to rotate following the vibration direction of the end of the flexible arm.

[0030] Rotating disk 13 is fixed to motor shaft 14 via screws. Bushing 15, bushing 24, a pair of angular contact bearings 17, bearing end cap 18, bearing bracket 19, and mounting bracket 20 form a rigid support structure that transmits forces acting on rotating disk 13 to chassis 21, preventing them from being directly applied to motor shaft 14 and rotating motor 23. This ensures smooth operation of rotating disk 13 while minimizing the additional load on the brushless motor, thereby optimizing overall system performance. Rotating motor 13 provides the required rotational torque for rotating disk 13.

[0031] In terms of material selection, the motor shaft 14 and the sleeve 24 are made of 45 steel, while other components are made of aluminum alloy 6063 to ensure the structural strength and lightweight design.

[0032] like Figure 3 As shown, the diameters of the chassis 21 and the top plate 28 are determined according to the outer diameter of 200 mm at the end of the three-degree-of-freedom flexible manipulator. The chassis 21 can be installed at the end of the manipulator, while the top plate 28 can be used to install the manipulator end actuator, such as a mechanical gripper, an actuator cylinder, etc. In order to ensure that the rotating disk can achieve 360° unlimited rotation, an electric slip ring 25 is installed under the top plate 228. The existence of the electric slip ring 25 ensures that the rotating mechanism 26 is not restricted by the swing arm mechanism A in terms of circuit wiring, so that the rotating mechanism B can rotate to the target position in the shortest path. The electric slip ring rotating shaft 26 is installed on the rotating disk of the rotating mechanism B, driving the electric slip ring 25 to rotate at the same speed as the rotating disk. The material of the support frame 27 is Q235 carbon structural steel, while other components are made of aluminum alloy 6063 to ensure the system's firmness and lightweight design. The rotating structure B can rotate 360° following the vibration direction of the flexible arm end. The motor of the swing arm mechanism A can swing according to the speed calculated by the cosine modulation anti-disturbance controller. It can only swing within a range of 180° and cannot rotate a full circle.

[0033] It also includes a control module, which includes a controller and a gyroscope. The controller is connected to the gyroscope, and the controller is electrically connected to the swing arm motor and the rotary motor. The gyroscope is used to obtain the acceleration values ​​of the end of the flexible arm in the X direction and the Y direction and send them to the controller. The controller calculates the rotation speed of the swing arm mechanism based on the acceleration values ​​of the end of the flexible arm in the X direction and the Y direction through a preset cosine modulation anti-disturbance control algorithm, and controls the swing arm motor to operate at this rotation speed.

[0034] The control block diagram of the traditional active disturbance rejection controller for controlling the swing dynamic vibration absorber is as follows: Figure 4 shown.

[0035] The control block diagram of the cosine modulation active disturbance rejection controller used in this application to control the swing dynamic vibration absorber is as follows: Figure 5As shown. The cosine modulation active disturbance rejection controller has a total of five parameters, which are the estimated values ​​of the system mechanism driving characteristic coefficient ; Bandwidth of error feedback control rate ; Extended state observer bandwidth ;TD tracking speed factor ;TD filter factor .

[0036] Compared with the traditional classic active disturbance rejection controller, this controller has the following characteristics:

[0037] 1. The tracking-differentiator is moved from the input to the output. On the one hand, this is because the expected signal is 0 for this vibration suppression algorithm, so a tracking-differentiator is not needed. On the other hand, the modulated cosine output has step values, and the tracking-differentiator can smoothly handle this sudden change.

[0038] 2. Traditional nonlinear ADRC requires adjustment of 12 parameters, and linear ADRC requires adjustment of 6 parameters. After pole configuration, linear ADRC only requires adjustment of 3 parameters, allowing it to be quickly deployed in engineering applications.

[0039] 3. In order to reduce the impact of the motor, a speed output modulation method is proposed. After simulation and experimental verification, this method can significantly reduce the impact of the motor and provide a basis for vibration suppression.

[0040] 4. This controller inherits the model-independence characteristics of the traditional classic ADRC, so that the dynamic vibration absorber can suppress the vibration of the flexible arm without relying on the mathematical model.

[0041] The circuit connection diagram of the pendulum ball dynamic vibration absorber is as follows: Figure 6 As shown, the dynamic vibration absorber's main power supplies are 24V and 5V. To ensure free rotation of the electrical components in the swing arm mechanism without wiring constraints, the wiring must pass through slip rings. The swing arm motor's speed and power also determine the output frequency of the force. The selected brushless swing arm motor has a torque of 5 Nm and a speed of 505 rpm. Calculations indicate that the maximum swing frequency can reach 9 Hz, making this dynamic vibration absorber suitable for low-frequency vibrations below 9 Hz.

[0042] The communication method between the various peripherals of the swing ball dynamic vibration absorber and the main control board is as follows Figure 7As shown in the figure, the system primarily consists of the CAN protocol, serial communication, and external interrupts. The six-axis electronic gyroscope module measures the X and Y accelerations of the flexible arm's end in real time, sending these values ​​to the STM32F103 industrial control board via the serial port. The industrial control board calculates the rotation angle of the rotating mechanism based on these X and Y accelerations and uses these accelerations as input for the cosine modulation auto-disturbance rejection algorithm. The cosine modulation auto-disturbance rejection algorithm calculates the rotational speed of the swing arm mechanism's motor. The calculated rotation angle and speed are transmitted to the corresponding motors via the CAN interface. Upon receiving the rotation angle information, the motors rotate to the corresponding angles. Upon receiving the rotation speed information, the two swing arm motors synchronize their swings.

[0043] The principle diagram of how the swing arm mechanism can achieve vibration suppression is as follows Figure 8 shown.

[0044] The resultant force along the X direction at this time is expressed as follows:

[0045] (1)

[0046] The resultant force along the Y direction is given by the following formula:

[0047] (2)

[0048] When the pendulum lengths L1=L2=L, m1=m2=m, and the deflection angle θ of the pendulum ball relative to the Y axis is the same, the final resultant force along the X direction is as follows:

[0049] (3)

[0050] The magnitude of the resultant force along the Y direction is given by the following formula:

[0051] (4)

[0052] Where, is the initial position of the ball swing.

[0053] By analyzing Equations (3) and (4), we can see that the resultant force of the two pendulum balls in the X direction is zero, while the magnitude of the resultant force in the Y direction is positively correlated with the angular velocity ω. In addition, as the balls continue to swing, the direction of the resultant force in the Y direction will also move on the positive and negative axes. When the swing frequency of the two balls is consistent with the vibration frequency of the flexible arm, and the swing direction of the balls is opposite to the vibration direction of the flexible arm, the condition of applying opposite forces to the vibration direction of the flexible arm is achieved. In this case, the vibration can be effectively suppressed, achieving the goal of suppressing the vibration of the flexible arm.

[0054] The above are only embodiments of the present invention. Common knowledge such as the known specific structures and characteristics in the scheme are not described in detail here. Ordinary technicians in the field are aware of all common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all existing technologies in the field, and have the ability to apply conventional experimental means before that date. Ordinary technicians in the field can improve and implement this scheme in combination with their own abilities under the inspiration given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A swing-type low-frequency active dynamic vibration absorbing device and its control system, characterized by: It includes a swing arm mechanism, a rotating mechanism and a rotating disk, the swing arm mechanism includes a pendulum, a swing rod, a swing arm motor, and a motor bracket, the swing arm mechanism includes a first swing arm mechanism and a second swing arm mechanism, which are symmetrically arranged on the upper end of the rotating disk, the swing arm motor is located at the upper end of the motor bracket and fixedly connected to the motor bracket, the rotating disk is located at the lower end of the motor bracket and fixedly connected to the motor bracket, the pendulum is connected to the swing rod flange, the swing rod is connected to the motor shaft of the swing arm motor, and the swing arm mechanism also includes a supporting device, which is used to provide supporting force for the motor shaft; The rotating mechanism includes a rotating motor, a rigid support structure, and a chassis. The motor shaft of the rotating motor is fixedly connected to the rotating disk. The rigid support structure connects the rotating disk and the chassis. The rotating mechanism is used to rotate in the vibration direction of the end of the flexible arm. It also includes a control module, which includes a controller and a gyroscope. The controller is connected to the gyroscope, and the controller is electrically connected to the swing arm motor and the rotary motor. The gyroscope is used to obtain the acceleration values ​​of the end of the flexible arm in the X direction and the Y direction and send them to the controller. The controller calculates the rotation speed of the swing arm mechanism based on the acceleration values ​​of the end of the flexible arm in the X direction and the Y direction through a preset cosine modulation anti-disturbance control algorithm, and controls the swing arm motor to operate at this rotation speed.

2. The swing-type low-frequency active dynamic vibration absorbing device and its control system according to claim 1, characterized in that: The supporting device includes a bearing bracket, a connecting plate, a sleeve, a deep groove ball bearing and a bearing lower bracket. The motor shaft of the swing arm motor is provided with a sleeve. The deep groove ball bearing is arranged on the bearing bracket and cooperates with the sleeve. The lower end of the bearing lower bracket is fixedly connected to the rotating disk, and the upper end is connected to the bearing bracket through a connecting plate.

3. The swing-type low-frequency active dynamic vibration absorbing device and its control system according to claim 2, characterized in that: The rigid support structure includes a fixing frame, a bearing frame, and an angular contact bearing. The sleeve cooperates with the motor shaft of the rotating motor, the bearing frame cooperates with the sleeve, the upper end of the fixing frame is fixedly connected to the lower end of the bearing frame, and the lower end of the fixing frame is fixedly connected to the chassis.

4. The swing-type low-frequency active dynamic vibration absorbing device and its control system according to claim 1, characterized in that: The pendulum is also provided with a pendulum cover, which is processed with an annular groove, and a detachable rubber sealing strip is provided in the annular groove.

5. The swing-type low-frequency active dynamic vibration absorbing device and its control system according to claim 1, characterized in that: It also includes a top plate, which is located above the swing arm mechanism. An electric slider is provided below the top plate. The rotating shaft of the electric slider is fixedly connected to the rotating plate. The controller is electrically connected to the swing arm motor and the rotating motor through the electric slider.

6. A swing-type low-frequency active dynamic vibration absorbing device and a control method thereof, characterized in that: A swing-type low-frequency active dynamic vibration absorbing device and a control system thereof as described in any one of claims 1 to 5 are used.

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