Fluid handling arm with automatic swivel joint and control system and method thereof

Abstract

The application discloses an automatic rotating joint for a fluid loading and unloading arm, which comprises relatively rotatable outer and inner tubes, wherein the outer tube is coaxially arranged on the inner tube, the inner tube is arranged in the outer tube, and ball bearings and ball bearing grooves are arranged between the inner and outer tubes; a hard stainless steel pipe is externally connected to the inner tube or the outer tube, a ratchet wheel is arranged on the hard stainless steel pipe, and the hard stainless steel pipe is axially and radially fixed; the automatic rotating joint further comprises a pawl for cooperating with the ratchet wheel and a power device for driving the pawl to rotate the ratchet wheel; under the action of the power device, the ratchet wheel drives the outer tube fixedly connected thereto to rotate relative to the inner tube, thereby achieving the active rotation of the inner and outer tubes and the relative rotation of two pipe sections of a loading and unloading arm connected with the inner and outer tubes. The application can reduce the volume and weight of a transmission system, reduce the installation precision requirement, and meet the actual application requirement of the fluid loading and unloading arm.

Description

Technical Field

[0001] This invention relates to the field of fluid loading and unloading arm technology, and in particular to an automatic rotary joint for a fluid loading and unloading arm, as well as a control system and method for the aforementioned automatic rotary joint for a fluid loading and unloading arm. Background Technology

[0002] Currently, rotary joints used in petroleum, chemical, and other fluid applications are typically made of steel. They consist of a fixed inner tube and a rotatable outer tube coaxially assembled. Ball bearings are installed between the inner and outer tubes to reduce friction. The outer tube can rotate 360 ​​degrees around its axis, while the inner tube serves as the liquid flow pipe. The connections are sealed, and high precision is required for the processing and installation of both the inner and outer pipes. Multiple rotary joints are connected by rigid tubing to form fluid loading and unloading arms. Rotary joints are used at the connections of these rigid tubing arms to expand the degrees of freedom and operating space.

[0003] Traditional fluid loading and unloading boom rotary joints rotate passively, driven by the pushing, pulling, and rotating of the rigid pipes of the boom by loading and unloading personnel to meet the needs of loading and unloading operations. With the development of industrial automation, fluid loading and unloading booms are gradually transforming into fully intelligent and automatic operations. The posture changes of automatic loading and unloading booms have changed from passive to active, and the key lies in the automatic movement of the rotary joint.

[0004] In existing published patents (application numbers: 202321581603.6 and 202510139514.3), worm gear and gear transmission are used as the main power input mechanism of the rotary joint. Although they have the advantages of large transmission torque and continuous and stable operation, they have many shortcomings: 1. Complex transmission mechanism: The reducer is large and heavy. The motor, reducer and gear or worm gear mechanism are attached to the rotary joint of the loading and unloading arm, which increases the volume and weight of the loading and unloading arm and increases the drive load of the automatic loading and unloading arm. 2. High manufacturing cost: The turbine and worm gear have high processing and manufacturing costs. The turbine and worm gear transmission method requires high installation accuracy. The turbine is mounted on the outer flange of the rotary joint and must be tightly fitted with the fixed worm gear. In addition, the entire component must move together with the loading and unloading arm, resulting in high manufacturing costs. 3. High installation accuracy requirements: In gear transmission, in order to ensure accuracy, the installation accuracy requirements for the large and small gear shafts are high. Once there is meshing clearance in the gear transmission, it will affect the rotation angle. 4. Not suitable for high-speed continuous operation: The special anti-leakage structure of the rotary joint of the loading and unloading arm is not suitable for high-speed continuous operation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing an automatic rotary joint for fluid loading and unloading arms that can reduce the size and weight of the transmission system, reduce the installation accuracy requirements, and meet the actual application needs of fluid loading and unloading arms.

[0006] Another technical problem to be solved by the present invention is to provide a control system and method for the automatic rotary joint of the above-mentioned fluid loading and unloading arm.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solution. The present invention is an automatic rotary joint for a fluid loading and unloading arm. The automatic rotary joint includes an outer tube and an inner tube that can rotate relative to each other. The outer tube and the inner tube are coaxially installed, with the inner tube inside and the outer tube outside. Ball bearings and ball bearing grooves are provided between the inner tube and the outer tube. A rigid stainless steel pipe is connected to the inner tube or the outer tube. A ratchet is installed on the rigid stainless steel pipe and is fixed axially and radially. The automatic rotary joint also includes a pawl for engaging with the ratchet and a power device for driving the pawl to rotate the ratchet. Under the action of the power device, the ratchet drives the outer tube fixedly connected to it to rotate relative to the inner tube, realizing the active rotation of the inner and outer tubes, and achieving the relative rotation of the two pipe sections of the loading and unloading arm connected to the inner and outer tubes.

[0008] The technical problem to be solved by the present invention can also be further achieved through the following technical solution: for the automatic rotary joint for the fluid loading and unloading arm described above, the connection method of the hard stainless steel pipe is welding or flange installation.

[0009] The technical problem to be solved by the present invention can also be further achieved by the following technical solution: For the automatic rotary joint for the fluid loading and unloading arm described above, the power device drives the pawl through a rotary disk, and the pawl is eccentrically mounted on the rotary disk; the power device adopts a servo motor or a stepper motor, the rotary disk is connected to the output shaft of the geared motor, and is connected by a flat key and fixed at the end; the pawl is mounted on a circle with a radius of r concentric with the rotary disk shaft through the pawl shaft, the pawl is hinged to the pawl shaft, a pawl groove is opened on the rotary disk along the radial direction, a compression spring is installed on the side of the pawl groove to press the pawl, so that it can reliably contact the ratchet, a compression spring is installed on both sides of the pawl shaft and the end of the pawl, the compression springs on both sides and the fixed end of the compression spring are mounted on the pawl shaft, and the other side of the compression spring is fixed to the end of the pawl.

[0010] The technical problem to be solved by this invention can also be further achieved through the following technical solution: For the automatic rotary joint for the fluid loading and unloading arm described above, if the motor speed is... If the number of ratchet teeth is Z and the number of pawls is m, then the ratchet rotation speed is... The automatic speed of the ratchet and rotary joint is adjusted by controlling the motor speed, the number of pawls, and the number of ratchet teeth; the speed of the rotary joint during continuous operation is less than 90° / s; when automatically rotating to adjust the position of the loading and unloading arm, the angle range of a single continuous rotation does not exceed 360°, that is, within ±180°.

[0011] The technical problem to be solved by the present invention can also be further achieved through the following technical solution: For the automatic rotary joint for the fluid loading and unloading arm described above, the distance between the axis of the rotating disk and the axis of the ratchet is L, the length of the pawl is l1, and the radius of the ratchet is R. When the ratchet requires the least torque to rotate; when When the ratchet requires the greatest torque to rotate, when... When the ratchet and pawl are in contact, they are in contact; otherwise, they will not be able to contact and thus cannot generate a driving effect. The distance between the center of the rotating disk shaft and the center of the ratchet shaft must satisfy the following condition. .

[0012] The technical problem to be solved by the present invention can also be further achieved through the following technical solutions: For the automatic rotary joint for the fluid loading and unloading arm described above, each tooth on the ratchet is symmetrical on both sides, and the contact surfaces with the pawl on both sides are the same; the pawl is hinged on the rotating disk, and the pawl is limited by the limiting groove of the rotating disk and the compression spring. When the rotating disk rotates in the forward and reverse directions, the pawl force acts on the ratchet teeth, causing the ratchet to rotate in the forward and reverse directions; a soft, high-friction noise-reducing material or coating is added to the contact area between the pawl and the ratchet teeth; the ratchet adopts a hollow structure design.

[0013] The technical problem to be solved by the present invention can also be further achieved by the following technical solution: For the automatic rotary joint for the fluid loading and unloading arm described above, four pawls are installed on the rotary disk, and the four pawls are evenly distributed along a circle with a radius of r.

[0014] The technical problem to be solved by the present invention can also be further achieved by the following technical solution: For the automatic rotary joint for fluid loading and unloading arm described above, a control system for the automatic rotary joint for fluid loading and unloading arm is provided. The system includes a ratchet rotation angle measurement module, a motor speed control and measurement module, and a ratchet rotation angle control and measurement module. In the ratchet rotation angle measurement module, the angle sensor is installed coaxially with the ratchet, that is, it is installed on the end face of the ratchet and coaxial with the ratchet, and a damping buffer structure is added. In the motor speed control and measurement module, the drive motor is either a servo motor or a stepper motor; the motor controller sends a pulse signal to change the pulse frequency and thus change the motor speed; the motor output shaft speed is measured by an encoder and the measured value is fed back to the motor controller to adjust the pulse frequency so that the motor speed is stabilized at the set value. In the ratchet angle control and measurement module, the ratchet angle control is implemented by a programmable logic controller (PLC). The ratchet angle sensor measures the actual angle and transmits the measured value to the PLC via serial port, bus, or network communication. To enable the ratchet to quickly and accurately reach the set value, the PLC uses a PID position control algorithm to calculate the control quantity for the motor, causing the motor to rotate and drive the pawl and ratchet to rotate rapidly to reach the set position angle.

[0015] The technical problem to be solved by the present invention can also be further achieved through the following technical solution: For the control system of the automatic rotary joint for the fluid loading and unloading arm described above, a control method for the automatic rotary joint for the fluid loading and unloading arm comprises the following steps: (1) Based on the specific requirements of the fluid loading and unloading operation, determine the target position that the loading and unloading arm needs to achieve, calculate the ratchet setting angle corresponding to the target position, and input the setting angle into the control system. (2) Activate the angle sensor to start measuring the rotation angle of the ratchet in real time and continuously transmit the measurement data to the controller using a specific communication protocol; (3) The controller continuously receives the measurement data transmitted from the angle sensor and preprocesses the data. Then, the controller calculates the difference between the ratchet setting angle set in the initial setting and the actual measured angle received in real time. This difference is used as an important input parameter for the subsequent control algorithm. (4) The controller uses the PID position control algorithm based on the calculated difference, taking into account the dynamic performance and steady-state accuracy of the system, to generate control commands for the motor. During the calculation process, the controller will dynamically adjust the parameters of the control algorithm according to the actual response of the system to optimize the control effect. (5) The motor controller receives the control command generated by the controller and adjusts the pulse frequency according to the command, thereby changing the speed of the motor. After the motor runs stably, it drives the pawl and ratchet to rotate, thereby adjusting the position of the loading and unloading arm. (6) The controller continuously monitors the measurement data transmitted by the angle sensor and judges in real time whether the actual measured angle has reached the set angle. When the actual measured angle reaches the set angle, it means that the loading and unloading arm has been adjusted to the target position. At this time, the controller sends a stop signal to the motor controller, the motor controller immediately stops sending pulse signals, the motor stops rotating, and the position adjustment of the loading and unloading arm is completed.

[0016] The technical problem to be solved by the present invention can also be further achieved through the following technical solution: Regarding the control method for the automatic rotary joint of the fluid loading / unloading arm described above, the specific implementation steps of the PID position control algorithm are as follows: (1) Definition of input quantity The difference between the set angle θ_set and the actual measured angle θ_actual is used as the algorithm input, i.e., the error value: e(t) = θ_set - θ_actual Where θ_set is the ratchet set angle corresponding to the target pose, and θ_actual is the actual ratchet angle measured in real time by the angle sensor; (2) Calculation of control quantity The control quantity is calculated using an incremental PID algorithm, and the formula is as follows: Δu(t) = K_p[e(t) - e(t-1)] + K_i e(t) + K_d[e(t) - 2e(t-1) + e(t-2)] The proportional coefficient K_p: quickly adjusts the output according to the magnitude of the error, shortening the response time; Integral coefficient K_i: Eliminates long-term accumulated static error and improves steady-state accuracy; Differential coefficient K_d: predicts the trend of error change and suppresses overshoot or oscillation; (3) Parameter adaptive adjustment Based on the real-time load torque changes of the loading arm, the PID parameters are dynamically optimized using fuzzy inference rules. When |e(t)| is large: increase K_p to speed up the system response and quickly reduce the error; When |e(t)| is small: increase K_i to eliminate residual steady error and ensure positioning accuracy; When de(t) / dt is large: increase K_d to suppress overshoot in advance and avoid oscillation; (4) Actuator drive The control quantity Δu(t) calculated and output by the PID controller is converted into a motor pulse frequency adjustment quantity: Δu(t)>0: Increasing the pulse frequency accelerates the forward rotation of the motor; Δu(t)<0: Reduce the pulse frequency or reverse the modulation to slow down or reverse the motor; Δu(t)=0: Maintain the current pulse frequency, and the motor runs at a constant speed; The motor controller adjusts the servo motor speed in real time according to the modulated pulse signal, driving the pawl and ratchet to rotate, thereby realizing continuous adjustment of the loading and unloading arm's posture; (5) Safety boundary constraints Software limit protection: When the actual angle is detected to exceed the ±180° pose adjustment range, an emergency stop and alarm will be triggered immediately; Speed ​​protection: When the motor speed exceeds the threshold of 120° / s, the pulse signal is forcibly cut off, and the motor stops running; Protection logic takes precedence over normal control procedures to ensure the system can be safely shut down under abnormal conditions.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Reduced size and weight: This invention adopts a two-way ratchet multi-head pawl drive, which reduces the size and weight of the transmission system compared with worm gear and gear drive, and reduces the drive load of the automatic loading and unloading arm; 2. Reduced installation accuracy requirements: The ratchet and pawl transmission method of this invention greatly reduces the installation accuracy requirements, thereby reducing installation difficulty and cost; 3. Reduced costs: This invention avoids the high-precision machining and installation requirements of worm gears and gear drives, thus reducing manufacturing costs; 4. Meets practical application requirements: Through the rational design of the ratchet, pawl structure and control system, this invention can meet the speed and rotation angle requirements of the fluid loading and unloading arm in practical applications, and realize automated operation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the flange-type and welded rotary joints of the present invention; Figure 2 This is a schematic diagram of the ratchet and pawl of the present invention; Figure 3 for Figure 2 A magnified view of a portion of the image; Figure 4 for Figure 2 A cross-sectional view of the structure along the AA direction; Figure 5 This is a schematic diagram of the speed control principle of the present invention; Figure 6 This is a schematic diagram of the corner control principle of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 embodiments of the present invention, not all embodiments. 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.

[0020] Reference Figure 1-6An automatic rotary joint for fluid loading and unloading arms is disclosed, primarily used in fluid loading and unloading arms to enable active rotation of the loading and unloading arm pipeline, thereby meeting the position adjustment requirements under different operating scenarios. The automatic rotary joint includes a relatively rotatable outer pipe 2 and an inner pipe 3, coaxially mounted with the inner pipe 3 inside and the outer pipe 2 outside. Ball bearings and ball bearing grooves are provided between the inner pipe 3 and the outer pipe 2 to reduce friction during rotation. A rigid stainless steel pipe 4 is connected to either the inner pipe 3 or the outer pipe 2. Preferably, the rigid stainless steel pipe 4 is connected by welding or flange installation to ensure the stability and sealing of the connection. A sealing groove and sealing ring are provided at the connection between the rotary joint and the outer pipe 2 to prevent liquid leakage from the pipeline. Additionally, leak-proof structures are designed on the inner and outer pipe 2 walls of the rotary joint. The inner pipe 3, outer pipe 2, and all components are manufactured and assembled with high precision to prevent liquid leakage.

[0021] A ratchet 1 is installed on the hard stainless steel pipe 4 and fixed axially and radially. The specific installation method varies depending on the pipe connection method: for flange connection, multiple bolts are used to circumferentially fix the coaxial ratchet 1 at the flange of the outer pipe 2 of the rotary joint; for welded connection, the ratchet 1 is installed on the connecting pipe and fixed axially and radially. This installation method makes the ratchet 1 tightly connected to the outer pipe 2 and can move with the outer pipe 2, providing a basis for subsequent active rotation.

[0022] The automatic rotary joint also includes a pawl 6 for engaging with the ratchet 1 and a power device for driving the pawl 6 to rotate the ratchet 1. Under the action of the power device, the ratchet 1 drives the outer tube 2, which is fixedly connected to it, to rotate relative to the inner tube 3, realizing the active rotation of the inner tube 3 and the outer tube 2. This achieves the relative rotation of the two pipe sections of the loading and unloading arm connected to the inner tube 3 and the outer tube 2. In practical applications, multiple automatic rotary joints can be used in combination. The axes of adjacent rotary joints are installed at 90 degrees on the loading and unloading arm, which will form a 3D working envelope. Specifically: The power unit drives the pawl 6 through the rotary disk 7. The pawl 6 is eccentrically mounted on the rotary disk 7. The power unit uses a servo motor or a stepper motor and is located on the side of the ratchet 1. The rotary disk 7 is connected to the output shaft of the reduction motor and is connected with a flat key and fixed at the end. During operation, the rotary disk 7 drives the pawl 6 to move. The pawl 6 interacts with the ratchet 1, causing the ratchet 1 to rotate, which in turn drives the outer tube 2, which is fixedly connected to it, to rotate relative to the inner tube 3, thereby realizing the active rotation of the inner tube 3 and the outer tube 2, and achieving the relative rotation of the two pipe sections of the loading and unloading arm connected to the inner tube 3 and the outer tube 2. Pawl 6 is mounted on a circle with radius r, concentric with the axis of the rotating disk 7, via pawl shaft 9. Pawl 6 is hinged to pawl shaft 9. Pawl groove 8 is formed on the rotating disk 7 along the radial direction. A compression spring is installed on the side of pawl groove 8 to press pawl 6, so that it can reliably contact ratchet 1. Compression springs 5 ​​are installed on both sides of the ends of pawl shaft 9 and pawl 6. The fixed ends of the compression springs 5 ​​on both sides are mounted on pawl shaft 9. Cotter pins 10 are also installed on pawl shaft 9 for anti-loosening. The other side of the compression spring 5 is fixed to the end of pawl 6, ensuring sufficient pressure contact between pawl 6 and ratchet 1. Furthermore, pawl groove 8 limits the movement of pawl 6, ensuring that pawl 6 will not disengage from ratchet 1 during operation, thereby ensuring the reliability of transmission.

[0023] Each tooth on ratchet 1 is symmetrical on both sides, and the contact surfaces with pawl 6 are the same on both sides. This ensures that pawl 6 is evenly stressed when ratchet 1 rotates in both directions, guaranteeing the smoothness and reliability of the transmission. Pawl 6 is hinged to the rotating disk 7 and is limited by the limiting groove of the rotating disk 7 and the compression spring 5. When the rotating disk 7 rotates in both directions, the force of pawl 6 acts on the teeth of ratchet 1, causing ratchet 1 to rotate in both directions. Soft, high-friction noise-reducing materials or coatings, such as rubber, are added to the contact area between pawl 6 and ratchet 1 teeth, effectively reducing the noise generated when ratchet 1 contacts pawl 6 and improving the working environment. The ratchet 1 adopts a hollow structure design, which reduces the weight of the ratchet 1 while meeting the transmission requirements, thereby reducing the weight of the entire rotary joint, reducing the drive load, and improving the operating efficiency of the system.

[0024] Four pawls 6 are installed on the rotating disk 7. The four pawls 6 are evenly distributed along a circle with a radius of r. By arranging multiple pawls 6 on the rotating disk 7, the intermittent time of the ratchet 1 can be reduced and the rotation frequency can be increased under the condition that the motor speed is constant, so that the rotation process is more stable and continuous.

[0025] Speed ​​calculation: If the motor speed is If the number of teeth on ratchet 1 is Z and the number of pawls 6 is m, then the rotational speed of ratchet 1 is... The speed is controlled by adjusting the motor speed, the number of pawls 6, and the number of teeth on ratchet 1 to adjust the automatic speed of ratchet 1 and rotary joint, so as to meet the speed requirements in different working scenarios. Rotation speed limit: The rotation speed of the rotary joint is generally below 90° / s during continuous operation. Even if the speed is increased, it will not exceed 120° / s. When automatically rotating to adjust the position of the loading and unloading arm, the angle range of a single continuous rotation does not exceed 360°, that is, within ±180°, to ensure the safety and stability of the rotation process.

[0026] The distance between the axis of the rotating disk 7 and the axis of the ratchet 1 is L, the length of the pawl 6 is l1, and the radius of the ratchet 1 is R. When the torque required to rotate ratchet 1 is minimal, when When the torque required to rotate ratchet 1 is at its maximum, when... When the ratchet 1 is in contact with the pawl 6, then the ratchet 1 and pawl 6 will not be in contact, and no driving action can be generated. The distance between the axis of the rotating disk 7 and the axis of the ratchet 1 satisfies the following condition. The distance between the axis of the rotating disk 7 and the axis of the ratchet 1 meets the above conditions. Compared with worm gear and gear transmission, the ratchet 1 and pawl 6 method greatly reduces the installation accuracy requirements and reduces manufacturing and installation costs.

[0027] A control system for an automatic rotary joint for a fluid loading and unloading arm, the system comprising a ratchet 1 rotation angle measurement module, a motor speed control and measurement module, and a ratchet 1 rotation angle control and measurement module; In the ratchet 1 rotation angle measurement module, the angle sensor is coaxially mounted with the ratchet 1, that is, mounted on the end face of the ratchet 1 and coaxial with the ratchet 1, and equipped with a damping buffer structure, such as an embedded damping rubber bushing or an expansion damping ring. This installation method and the design of the damping buffer structure ensure measurement accuracy and prevent the contact impact between the ratchet 1 and the pawl 6 from affecting the stability of the measurement. The interference fit between the bushing and the pipe shaft needs to be moderate. Too large an amount will cause damping failure, and too small an amount will cause slippage, thereby ensuring that the angle sensor can accurately measure the rotation angle of the ratchet 1. In the motor speed control and measurement module, the drive motor is either a servo motor or a stepper motor; the motor controller sends a pulse signal, changes the pulse frequency and thus changes the motor speed; the motor output shaft speed is measured by an encoder, and the measured value is fed back to the motor controller to adjust the pulse frequency so that the motor speed is stabilized at the set value. Through this closed-loop control method, the motor speed can be precisely controlled to meet the requirements of different speeds of the rotary joint. In the ratchet 1 rotation angle control and measurement module, the ratchet 1 rotation angle control is implemented by a programmable logic controller (PLC). The ratchet 1 rotation angle sensor measures the actual rotation angle and transmits the measured value to the PLC via serial port, bus, or network communication. To enable the ratchet 1 to quickly and accurately reach the set value, the PLC uses a PID position control algorithm to calculate the control quantity for the motor, causing the motor to rotate and drive the pawl 6 and ratchet 1 to rotate rapidly to the set position angle. This enables precise control of the ratchet 1 rotation angle, ensuring that the loading and unloading arm can be accurately adjusted to the target position.

[0028] A control method for an automatic rotary joint used in a fluid loading / unloading arm, comprising the following steps: (1) Based on the specific requirements of fluid loading and unloading operations, determine the target position and orientation that the loading and unloading arm needs to achieve, and calculate the ratchet 1 setting angle corresponding to the target position and orientation. Input the setting angle into the control system so that the accurate target position and orientation and the setting angle can ensure that the subsequent adjustment of the loading and unloading arm is accurate.

[0029] (2) Start the angle sensor to start measuring the rotation angle of ratchet 1 in real time, and continuously transmit the measurement data to the controller in a specific communication protocol so that the controller can understand the actual rotation of ratchet 1 in a timely manner.

[0030] (3) The controller continuously receives the measurement data transmitted from the angle sensor and preprocesses the data. Then, the controller calculates the difference between the two in real time based on the initial ratchet 1 set angle and the received actual measurement angle. This difference serves as an important input parameter for the subsequent control algorithm and reflects the gap between the current pose of the loading arm and the target pose.

[0031] (4) The controller uses the PID position control algorithm based on the calculated difference, taking into account the dynamic performance and steady-state accuracy of the system, to generate control commands for the motor. During the calculation process, the controller will dynamically adjust the parameters of the control algorithm according to the actual response of the system to optimize the control effect. The PID position control algorithm can accurately calculate the control input of the motor based on factors such as the magnitude and rate of change of the error, enabling the loading and unloading arm to quickly and accurately adjust to the target position. The specific implementation steps are as follows: (4.1) Input definition The difference between the set angle θ_set and the actual measured angle θ_actual is used as the algorithm input, i.e., the error value: e(t) = θ_set - θ_actual Where θ_set is the set angle of ratchet 1 corresponding to the target pose, and θ_actual is the actual angle of ratchet 1 measured in real time by the angle sensor; By calculating the error value, we can intuitively understand the deviation between the current pose of the loading arm and the target pose.

[0032] (4.2) Calculation of control quantity The control quantity is calculated using an incremental PID algorithm, and the formula is as follows: Δu(t) = K_p[e(t) - e(t-1)] + K_i e(t) + K_d[e(t) - 2e(t-1) + e(t-2)] The proportional coefficient K_p: quickly adjusts the output according to the magnitude of the error, shortening the response time; Integral coefficient K_i: Eliminates long-term accumulated static error and improves steady-state accuracy; Differential coefficient K_d: predicts the trend of error change and suppresses overshoot or oscillation; (4.3) Adaptive parameter adjustment Based on the real-time load torque changes of the loading arm, the PID parameters are dynamically optimized using fuzzy inference rules. When |e(t)| is large: increase K_p to speed up the system response and quickly reduce the error; When |e(t)| is small: increase K_i to eliminate residual steady error and ensure positioning accuracy; When de(t) / dt is large: increase K_d to suppress overshoot in advance and avoid oscillation; (4.4) Actuator Drive The control quantity Δu(t) calculated and output by the PID controller is converted into a motor pulse frequency adjustment quantity: Δu(t)>0: Increasing the pulse frequency accelerates the forward rotation of the motor; Δu(t)<0: Reduce the pulse frequency or reverse the modulation to slow down or reverse the motor; Δu(t)=0: Maintain the current pulse frequency, and the motor runs at a constant speed; The motor controller adjusts the servo motor speed in real time according to the modulated pulse signal, driving the pawl 6 and ratchet 1 to rotate, thereby realizing continuous adjustment of the loading and unloading arm's posture; (4.5) Safety boundary constraints Software limit protection: When the actual angle is detected to exceed the ±180° pose adjustment range, an emergency stop and alarm will be triggered immediately; Speed ​​protection: When the motor speed exceeds the threshold of 120° / s, the pulse signal is forcibly cut off, and the motor stops running; Protection logic takes precedence over normal control procedures to ensure the system can be safely shut down under abnormal conditions.

[0033] (5) The motor controller receives the control command generated by the controller and adjusts the pulse frequency according to the command, thereby changing the speed of the motor. After the motor runs stably, it drives the pawl 6 and ratchet 1 to rotate, thereby adjusting the position of the loading and unloading arm. Through the precise control of the motor, the loading and unloading arm can be adjusted according to the predetermined trajectory and speed to meet the requirements of different operating scenarios.

[0034] (6) The controller continuously monitors the measurement data transmitted by the angle sensor and judges in real time whether the actual measured angle has reached the set angle. When the actual measured angle reaches the set angle, it means that the loading and unloading arm has been adjusted to the target position. At this time, the controller sends a stop signal to the motor controller, the motor controller immediately stops sending pulse signals, the motor stops rotating, and the position adjustment of the loading and unloading arm is completed.

[0035] In summary, the automatic rotary joint for fluid loading and unloading arms, its control system, and control method provided by this invention, through ingenious structural design and advanced control algorithms, realize the active rotation and precise posture adjustment of the loading and unloading arm pipeline. It has the advantages of small transmission system size, light weight, low installation accuracy requirements, and precise control, and can effectively improve the efficiency and safety of fluid loading and unloading operations.

Claims

1. An automatic rotary joint for a fluid loading / unloading arm, characterized in that: The automatic rotary joint includes an outer tube and an inner tube that can rotate relative to each other. The outer tube and the inner tube are coaxially installed, with the inner tube inside and the outer tube outside. There are balls and ball grooves between the inner tube and the outer tube. The inner tube or the outer tube is connected to a hard stainless steel pipe. A ratchet is installed on the hard stainless steel pipe and is fixed axially and radially. The automatic rotary joint also includes a pawl for engaging with the ratchet and a power device for driving the pawl to rotate the ratchet. Under the action of the power device, the ratchet drives the outer tube fixedly connected to it to rotate relative to the inner tube, realizing the active rotation of the inner and outer tubes, and achieving the relative rotation of the two pipe sections of the loading and unloading arm connected to the inner and outer tubes.

2. The automatic rotary joint for a fluid loading / unloading arm according to claim 1, characterized in that: The hard stainless steel pipes are connected by welding or flange installation.

3. The automatic rotary joint for a fluid loading / unloading arm according to claim 1, characterized in that: The power unit drives the pawl via a rotating disk, with the pawl eccentrically mounted on the rotating disk. The power unit uses a servo motor or a stepper motor. The rotating disk is connected to the output shaft of the geared motor and is fixed at the end with a key. The pawl is mounted on a circumference with radius r, concentric with the rotating disk shaft, via a pawl shaft. The pawl is hinged to the pawl shaft. A pawl groove is formed on the rotating disk along the radial direction. A compression spring is installed on the side of the pawl groove to press the pawl, ensuring reliable contact with the ratchet. Compression springs are installed on both sides of the pawl shaft and the end of the pawl. The fixed ends of the compression springs on both sides are mounted on the pawl shaft, and the other side of the compression spring is fixed to the end of the pawl.

4. The automatic rotary joint for a fluid loading / unloading arm according to claim 3, characterized in that: If the motor speed is If the number of ratchet teeth is Z and the number of pawls is m, then the ratchet rotation speed is... The automatic speed of the ratchet and rotary joint is adjusted by controlling the motor speed, the number of pawls, and the number of ratchet teeth; the speed of the rotary joint during continuous operation is less than 90° / s; when automatically rotating to adjust the position of the loading and unloading arm, the angle range of a single continuous rotation does not exceed 360°, that is, within ±180°.

5. The automatic rotary joint for a fluid loading / unloading arm according to claim 1, characterized in that: The distance between the center of the rotating disk and the center of the ratchet is L, the length of the pawl is l1, and the radius of the ratchet is R. When the ratchet requires the least torque to rotate; when When the ratchet requires the greatest torque to rotate, when... When the ratchet and pawl are in contact, they are in contact; otherwise, they will not be able to contact and thus cannot generate a driving effect. The distance between the center of the rotating disk shaft and the center of the ratchet shaft must satisfy the following condition. .

6. The automatic rotary joint for a fluid loading / unloading arm according to claim 1, characterized in that: Each tooth on the ratchet is symmetrical on both sides, and the contact surfaces with the pawl are the same on both sides. The pawl is hinged to the rotating disk and is limited by the limiting groove of the rotating disk and the compression spring. When the rotating disk rotates in the forward and reverse directions, the force of the pawl acts on the ratchet teeth, causing the ratchet to rotate in the forward and reverse directions. Soft, high-friction noise-reducing material or coating is added to the contact area between the pawl and the ratchet teeth. The ratchet uses a hollow structure design.

7. The automatic rotary joint for a fluid loading / unloading arm according to claim 1, characterized in that: Four pawls are installed on the rotating disk, and the four pawls are evenly distributed along a circle with a radius of r.

8. A control system for an automatic rotary joint for a fluid loading / unloading arm, characterized in that: The system is used to control the automatic rotary joint for the fluid loading and unloading arm as described in any one of claims 1-7. The system includes a ratchet rotation angle measurement module, a motor speed control and measurement module, and a ratchet rotation angle control and measurement module. In the ratchet rotation angle measurement module, the angle sensor is installed coaxially with the ratchet, that is, it is installed on the end face of the ratchet and coaxial with the ratchet, and a damping buffer structure is added. In the motor speed control and measurement module, the drive motor is either a servo motor or a stepper motor; the motor controller sends a pulse signal to change the pulse frequency and thus change the motor speed; the motor output shaft speed is measured by an encoder and the measured value is fed back to the motor controller to adjust the pulse frequency so that the motor speed is stabilized at the set value. In the ratchet angle control and measurement module, the ratchet angle control is implemented by a programmable logic controller (PLC). The ratchet angle sensor measures the actual angle and transmits the measured value to the PLC via serial port, bus, or network communication. To enable the ratchet to quickly and accurately reach the set value, the PLC uses a PID position control algorithm to calculate the control quantity for the motor, causing the motor to rotate and drive the pawl and ratchet to rotate rapidly to reach the set position angle.

9. A control method for an automatic rotary joint used in a fluid loading / unloading arm, characterized in that: This method uses the control system of the automatic rotary joint for the fluid loading / unloading arm as described in claim 8, and its steps are as follows: (1) Based on the specific requirements of the fluid loading and unloading operation, determine the target position that the loading and unloading arm needs to achieve, calculate the ratchet setting angle corresponding to the target position, and input the setting angle into the control system. (2) Activate the angle sensor to start measuring the rotation angle of the ratchet in real time and continuously transmit the measurement data to the controller using a specific communication protocol; (3) The controller continuously receives the measurement data transmitted from the angle sensor and preprocesses the data. Then, the controller calculates the difference between the ratchet setting angle set in the initial setting and the actual measured angle received in real time. This difference is used as an important input parameter for the subsequent control algorithm. (4) The controller uses the PID position control algorithm based on the calculated difference, taking into account the dynamic performance and steady-state accuracy of the system, to generate control commands for the motor. During the calculation process, the controller will dynamically adjust the parameters of the control algorithm according to the actual response of the system to optimize the control effect. (5) The motor controller receives the control command generated by the controller and adjusts the pulse frequency according to the command, thereby changing the speed of the motor. After the motor runs stably, it drives the pawl and ratchet to rotate, thereby adjusting the position of the loading and unloading arm. (6) The controller continuously monitors the measurement data transmitted by the angle sensor and judges in real time whether the actual measured angle has reached the set angle. When the actual measured angle reaches the set angle, it means that the loading and unloading arm has been adjusted to the target position. At this time, the controller sends a stop signal to the motor controller, the motor controller immediately stops sending pulse signals, the motor stops rotating, and the position adjustment of the loading and unloading arm is completed.

10. The control method for the automatic rotary joint of the fluid loading / unloading arm according to claim 9, characterized in that: The specific implementation steps of the PID position control algorithm are as follows: (1) Definition of input quantity The difference between the set angle θ_set and the actual measured angle θ_actual is used as the algorithm input, i.e., the error value: e(t) = θ_set - θ_actual Where θ_set is the ratchet set angle corresponding to the target pose, and θ_actual is the actual ratchet angle measured in real time by the angle sensor; (2) Calculation of control quantity The control quantity is calculated using an incremental PID algorithm, and the formula is as follows: Δu(t) = K_p[e(t) - e(t-1)] + K_i e(t) + K_d[e(t) - 2e(t-1) + e(t-2)] The proportional coefficient K_p: quickly adjusts the output according to the magnitude of the error, shortening the response time; Integral coefficient K_i: Eliminates long-term accumulated static error and improves steady-state accuracy; Differential coefficient K_d: predicts the trend of error change and suppresses overshoot or oscillation; (3) Parameter adaptive adjustment Based on the real-time load torque changes of the loading arm, the PID parameters are dynamically optimized using fuzzy inference rules. When |e(t)| is large: increase K_p to speed up the system response and quickly reduce the error; When |e(t)| is small: increase K_i to eliminate residual steady error and ensure positioning accuracy; When de(t) / dt is large: increase K_d to suppress overshoot in advance and avoid oscillation; (4) Actuator drive The control quantity Δu(t) calculated and output by the PID controller is converted into a motor pulse frequency adjustment quantity: Δu(t)>0: Increasing the pulse frequency accelerates the forward rotation of the motor; Δu(t)<0: Reduce the pulse frequency or reverse the modulation to slow down or reverse the motor; Δu(t)=0: Maintain the current pulse frequency, and the motor runs at a constant speed; The motor controller adjusts the servo motor speed in real time according to the modulated pulse signal, driving the pawl and ratchet to rotate, thereby realizing continuous adjustment of the loading and unloading arm's posture; (5) Safety boundary constraints Software limit protection: When the actual angle is detected to exceed the ±180° pose adjustment range, an emergency stop and alarm will be triggered immediately; Speed ​​protection: When the motor speed exceeds the threshold of 120° / s, the pulse signal is forcibly cut off, and the motor stops running; Protection logic takes precedence over normal control procedures to ensure the system can be safely shut down under abnormal conditions.

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