A large-scale macroalgae cultivation rope constant tension control device and method under variable load

Abstract

The application provides a large-scale algal cultivation rope constant tension control device and method under variable load, comprising a bottom plate, wherein the bottom plate is provided with a first rope pulling machine for maintaining the tension of the cultivation rope during the large-scale algal harvesting process, a second rope pulling machine for simulating the load force borne by the first rope pulling machine when the cultivation rope is dragged during the large-scale algal harvesting process, and a rope unwinding machine located between the first rope pulling machine and the second rope pulling machine and used for winding the cultivation rope, and the drive motors in the first rope pulling machine and the second rope pulling machine are connected with a PLC controller; the application has the beneficial effects that: a land-based constant tension test bench system is designed, the tension of the cultivation rope with large-scale algae is kept relatively stable under the variable load state, or the dragging is automatically paused when the dragging is stuck, the sudden disappearance of the force borne by the cultivation rope is avoided, the cultivation rope is prevented from being cut off by the knife due to the vertical oscillation or being pulled off due to the excessive force, a reference basis is provided for the actual application at sea, and the safety of the large-scale algal cultivation rope during the dragging process is ensured.

Description

Technical Field

[0001] This invention relates to the field of fishery equipment technology, and in particular to a device and method for controlling the constant tension of large algae cultivation ropes under variable load. Background Technology

[0002] Currently, when kelp seedlings are towed onto ships, continuous kelp cutting equipment is used to separate the ropes from the kelp. The existing continuous kelp cutting equipment mainly consists of a front guide roller, a lifting and conveying device, a cutting blade, a seedling rope traction device, a seedling rope storage device after harvesting, a kelp conveying device after cutting, and a kelp storage device. During the towing process, the cutting blade automatically cuts off the kelp roots attached to the rope. This process requires ensuring that the rope with kelp attached remains taut at all times and is continuously towed. However, during continuous kelp harvesting, the dragging speed and force of the kelp seedling ropes are easily affected by multiple factors such as ocean wind, waves, currents, and rafts. Excessive tension in the seedling ropes can easily cause them to break or undergo plastic deformation due to excessive stress. A sudden loss of tension in the seedling ropes will cause a sudden increase in the suspension angle of the kelp seedling ropes near the cutting blade, making them very easy to be cut by the blade or get stuck on the blade. Both of these situations will lead to harvesting interruption and affect the lifespan of the aquaculture ropes. Therefore, during kelp harvesting, it is necessary to keep the kelp seedling ropes traveling at a stable speed within a certain range and to keep the seedling ropes taut at all times to prevent damage to the seedling ropes. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a constant tension control device and method for large algae cultivation ropes under variable load, which solves the problems in the prior art where excessive tension of the seedling rope easily causes the rope to break due to excessive force or plastic deformation, and the sudden disappearance of the seedling rope tension leads to a sudden increase in the catenary angle of the kelp seedling rope near the cutting blade, making it very easy for it to be cut by the blade or get stuck on the blade.

[0004] To achieve the above and other related objectives, the present invention provides the following technical solution:

[0005] A constant tension control device for large algae cultivation ropes under variable load includes a base plate. The base plate is equipped with a first rope-pulling machine for maintaining the tension of the cultivation rope during the harvesting of large algae, a second rope-pulling machine for simulating the load force experienced by the first rope-pulling machine when dragging the cultivation rope during the harvesting of large algae, and a rope-releasing machine located between the first and second rope-pulling machines for winding up the cultivation rope. A support pulley that is slidably connected to the cultivation rope is also provided between the first and second rope-pulling machines. The top of the support pulley is equipped with a cutting blade for cutting off large algae attached to the cultivation rope. The drive motors of the first and second rope-pulling machines are both connected to a PLC controller.

[0006] In one embodiment of the present invention, the first rope pulling machine includes a first base frame, a variable frequency motor, a first torque sensor and a first winch sequentially mounted on the first base frame. The output shaft of the variable frequency motor is connected to the first output shaft of the first torque sensor through a first coupling. A first rotating shaft is connected to the second output shaft of the first torque sensor through a second coupling. The end of the first rotating shaft away from the first torque sensor passes through the first winch. The first winch is provided with a first traction disc.

[0007] In one embodiment of the present invention, the second rope pulling machine includes a second base frame, a servo motor, a second torque sensor, and a second winch sequentially mounted on the second base frame. A second rotating shaft is connected to the output shaft of the servo motor. The end of the second rotating shaft away from the servo motor is connected to the first output shaft of the second torque sensor via a third coupling. A third rotating shaft is connected to the second output shaft of the second torque sensor via a fourth coupling. The end of the third rotating shaft away from the second torque sensor passes through the second winch. A second traction disc is provided on the second winch.

[0008] In one embodiment of the present invention, an electromagnetic clutch is provided on the end of the second rotating shaft near the servo motor, located on the side of the third coupling. A pneumatic brake for providing damping torque is provided between the electromagnetic clutch and the third coupling. The pneumatic brake includes a pneumatic component mounted on the second base frame and a brake disc sleeved on the second rotating shaft.

[0009] A method for controlling the constant tension of a large algae cultivation rope under variable load, based on the aforementioned constant tension control device for large algae cultivation ropes, is applied to a second rope pulling machine and includes the following steps: The second rope pulling machine is used to simulate the random change of force value during the harvesting of large algae. The large algae cultivation rope is in the gap of the second rope pulling machine and is subjected to the pressure of the traction discs on both sides. There is no relative sliding between the large algae cultivation rope and the second traction disc on the second rope pulling machine. At this time, the electromagnetic clutch is in a disengaged state, and the damping torque of the second rope pulling machine is provided only by the pneumatic brake.

[0010] In one embodiment of the present invention, the required load force is set by pre-setting a variable load curve in the PLC controller or manually setting it on the touch screen. The corresponding pressure value is obtained according to the relationship between theoretical load force and pressure. The converted pressure value is then output through a model quantity to achieve proportional control of the pneumatic brake, thereby controlling the output torque of the second rope pulling machine. When the set load force increases, the pressure increases, the pneumatic brake tightens, and the output force of the second winch increases. When the set load force decreases, the pneumatic brake loosens, and the output force of the second winch decreases, thus realizing variable load simulation in the kelp harvesting process.

[0011] In one embodiment of the present invention, obtaining the corresponding pressure value based on the relationship between theoretical load force and pressure includes: determining the relationship between theoretical load force and pressure according to the following formula: Where P is the air pressure in the pneumatic cylinder of the pneumatic assembly; F 负载 R is the load force; r2 is the radius of the second traction disc; r2' is the distance from the center of the breeding rope to the arc of the second traction disc, which is theoretically calculated to be approximately the radius of the breeding rope; R is the radius of the air cylinder in the pneumatic assembly; u is the coefficient of friction; S is the domain of the brake pad in the brake disc, S=S1+S2+S3; x and y are the axes with the center of the brake disc as the origin, the horizontal axis as the X-axis, and the vertical axis as the Y-axis.

[0012] In one embodiment of the present invention, the method is applied to a first rope-pulling machine and includes the following steps: the first rope-pulling machine is used to maintain the tension of the aquaculture rope during the actual harvesting process. When the first rope-pulling machine pulls the aquaculture rope, in order to overcome the damping torque of the second rope-pulling machine, the first rope-pulling machine rotates. At this time, when the first rope-pulling machine rotates, the first traction disc opens and sends out the large algae aquaculture rope, thereby realizing the aquaculture rope being dragged with a dragging force; wherein, the tension of the first rope-pulling machine is set to a fixed value according to the required torque and the size of the winch.

[0013] In one embodiment of the present invention, the relationship between the PID control algorithm in the PLC controller and the dragging speed is dynamically adjusted. When the dragging force of the first rope-pulling machine decreases, the speed increases; when the dragging force increases, the speed decreases, maintaining relatively stable power. Furthermore, when the load force obtained after conversion from the value of the first torque sensor in the first rope-pulling machine is less than the set value, the output torque of the variable frequency motor is rapidly increased through the adjustment of the PID control algorithm. When the load force obtained after conversion from the value of the first torque sensor in the first rope-pulling machine is greater than the set value, the output torque of the variable frequency motor is reduced through the adjustment of the PID control algorithm, thereby achieving constant tension control during the harvesting of large algae.

[0014] In one embodiment of the present invention, the step of dynamically adjusting the relationship between the dragging speed and the PID control algorithm within the PLC controller includes: the logic control program in the PLC controller employs a PID control algorithm, using a proportional coefficient (K) p ), integral coefficient (K) i ) and differential coefficients (K dThe proportional, integral, and derivative components of the input are used to calculate the deviation value, and the result is used to control the output. When the feedback signal experiences a large deviation step, the proportional and derivative components work simultaneously to suppress the feedback input change caused by this deviation step, while also considering adding an integral component to eliminate residual error. The deviation value e(t) between the setpoint r(t) and the measured load force f(t) is used as the input signal, and its formula is as follows: e(t) = r(t) - f(t). PID control uses a linear combination of the proportional, integral, and derivative components of e(t) to form the control quantity, and its output signal is: After Laplace transform, the transfer function of the PID controller is:

[0015] As described above, the present invention provides a constant tension control device and method for large algae cultivation ropes under variable load, which has the following beneficial effects: The present invention uses a pre-set variable load curve in a PLC controller or manually sets the required load force on a touch screen. Based on the theoretical relationship between load force and pressure, the corresponding pressure value is obtained, and the converted pressure value is output through a model quantity to achieve proportional control of the pneumatic brake in the second rope-pulling machine to set the required load force. This simulates the random changes in force during the harvesting of large algae. The tension force of the first rope-pulling machine is set to a constant value. When the first rope-pulling machine drags different loads... When using a cultivation rope with load-bearing capacity, the PID control algorithm within the PLC controller dynamically adjusts its relationship with the dragging speed to achieve constant tension control during the harvesting of large algae. This solves the problems of excessive rope tension causing breakage or plastic deformation, and sudden loss of rope tension leading to a sudden increase in the catenary angle of the kelp seedling rope near the cutting blade, making it easy for the rope to be cut or jammed by the blade. During the harvesting of large algae, the speed of the cultivation rope remains stable within a certain range, and the rope is kept taut at all times to prevent damage. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of the constant tension control device for large algae cultivation ropes under variable load in the first embodiment of the present invention;

[0017] Figure 2 This is a front view schematic diagram of the constant tension control device for large algae cultivation ropes under variable load in the first embodiment of the present invention;

[0018] Figure 3 This is a top view schematic diagram of the constant tension control device for large algae cultivation ropes under variable load in the first embodiment of the present invention;

[0019] Figure 4This is a three-dimensional schematic diagram of the first rope-pulling machine in the variable load constant tension control device for large algae cultivation ropes in the first embodiment of the present invention.

[0020] Figure 5 This is a cross-sectional schematic diagram of the first rope-pulling machine in the variable load constant tension control device for large algae cultivation ropes in the first embodiment of the present invention.

[0021] Figure 6 This is a three-dimensional schematic diagram of the second rope-pulling machine in the variable load constant tension control device for large algae cultivation ropes in the first embodiment of the present invention.

[0022] Figure 7 This is a cross-sectional schematic diagram of the second rope-pulling machine in the variable load constant tension control device for large algae cultivation ropes in the first embodiment of the present invention.

[0023] Figure 8 This is a flowchart illustrating the method for controlling the constant tension of large algae cultivation ropes under variable load in the second embodiment of the present invention.

[0024] Figure 9 This is a schematic diagram of the integral interval of the brake disc in the constant tension control method for large algae cultivation ropes under variable load in the second embodiment of the present invention.

[0025] Figure 10 This is a schematic diagram illustrating the relationship between theoretical torque and pressure in the constant tension control method for large algae cultivation ropes under variable load in the second embodiment of the present invention.

[0026] Figure 11 This is a schematic diagram illustrating the relationship between theoretical load force and pressure in the method for controlling the constant tension of large algae cultivation ropes under variable load in the second embodiment of the present invention.

[0027] Figure 12 This is a schematic diagram of the electrical control principle of the second rope pulling machine in the method for controlling the constant tension of large algae cultivation ropes under variable load in the second embodiment of the present invention.

[0028] Figure 13 This is a constant tension logic control block diagram of the first rope pulling machine in the constant tension control method for large algae cultivation ropes under variable load in the second embodiment of the present invention.

[0029] Figure 14 This is a block diagram of the constant tension PID control principle in the constant tension control method for large algae cultivation ropes under variable load in the second embodiment of the present invention.

[0030] Figure 15 This is a schematic diagram of the electrical control system for the joint operation of the first and second rope pulling machines in the variable load constant tension control method for large algae cultivation ropes in the second embodiment of the present invention.

[0031] Component designation explanation

[0032] 1. Base plate; 2. First rope pulling machine; 201. First base frame; 202. Variable frequency motor; 203. First torque sensor; 204. First winch; 205. First coupling; 206. Second coupling; 207. First bearing seat; 208. First shaft; 3. Support pulley; 4. Slitting and cutting blade; 5. Aquaculture rope; 6. Second rope pulling machine; 601. Second base frame; 602. Servo motor; 603. Second torque sensor; 604. Second winch; 605. Electromagnetic clutch; 606. Pneumatic brake; 607. Second bearing seat; 608. Third coupling; 609. Fourth coupling; 610. Third bearing seat; 611. Second shaft; 612. Third shaft; 7. Rope releasing machine; 8. First traction disc; 9. Second traction disc; 10. Pneumatic assembly; 11. Brake disc. Detailed Implementation

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. It should be noted that, unless otherwise specified, the following embodiments and features described herein can be combined with each other.

[0034] The first embodiment of the present invention relates to a constant tension control device for large-scale algae cultivation ropes under variable load, namely a land-based constant tension experimental platform system. Please refer to [link to relevant documentation]. Figures 1 to 3 The system includes a base plate 1, on which are mounted a first rope-pulling machine 2 for maintaining the tension of the cultivation rope 5 during the harvesting of large algae, a second rope-pulling machine 6 for simulating the load force experienced by the first rope-pulling machine 2 when dragging the cultivation rope 5 during the harvesting of large algae, and a rope-releasing machine 7 located between the first rope-pulling machine 2 and the second rope-pulling machine 6 for winding up the cultivation rope 5. A support pulley 3, slidably connected to the large algae cultivation rope 5, is also provided between the first rope-pulling machine 2 and the second rope-pulling machine 6. The top of the support pulley 3 is equipped with a tool for cutting off the algae attached to the cultivation rope. The large algae-slicing blade 4 on rope 5, and the drive motors in the first rope pulling machine 2 and the second rope pulling machine 6 are both connected to the PLC controller, namely the variable frequency motor 202 and the servo motor 602 mentioned below; it should be noted that the present invention also includes measuring equipment such as a high-speed camera; the winch structure in the first rope pulling machine 2 and the second rope pulling machine 6 can be referred to in patent (2023107894042), and the specific structure of the rope releasing machine 7 can be referred to in patent (2022100476101).

[0035] like Figure 4 and Figure 5As shown, the first rope pulling machine 2 includes a first base frame 201, a variable frequency motor 202, a first torque sensor 203, and a first winch 204 sequentially mounted on the first base frame 201. The variable frequency motor 202 is equipped with an encoder. The output shaft of the variable frequency motor 202 is connected to the first output shaft of the first torque sensor 203 through a first coupling 205. A first rotating shaft 208 is connected to the second output shaft of the first torque sensor 203 through a second coupling 206. The end of the first rotating shaft 208 away from the first torque sensor 203 passes through the first winch 204. The first winch 204 is equipped with a first traction disc 8. The first base frame 201 is also equipped with a first bearing seat 207 located between the second coupling 206 and the first winch 204. The first rotating shaft 208 passes through the first bearing seat 207.

[0036] like Figure 6 and Figure 7 As shown, the second rope-pulling machine 6 includes a second base frame 601, a servo motor 602, a second torque sensor 603, and a second winch 604 sequentially mounted on the second base frame 601. A second rotating shaft 611 is connected to the output shaft of the servo motor 602. The end of the second rotating shaft 611 away from the servo motor 602 is connected to the first output shaft of the second torque sensor 603 via a third coupling 608. A third rotating shaft 612 is connected to the second output shaft of the second torque sensor 603 via a fourth coupling 609. The end of the third rotating shaft 612 away from the second torque sensor 603 passes through the second winch 604. A second traction disc 9 is provided on the second winch 604. It should be noted that a pressure block is provided on the traction disc, which serves to tighten the aquaculture rope 5. For details, please refer to patent (2023107894042).

[0037] An electromagnetic clutch 605 is located on the side of the third coupling 608 at the end of the second shaft 611 near the servo motor 602. The electromagnetic clutch 605 is mounted on the second shaft 611 via a clutch connecting flange. A pneumatic brake 606 for providing damping torque is provided between the electromagnetic clutch 605 and the third coupling 608. The pneumatic brake 606 includes a pneumatic assembly 10 mounted on the second base frame 601 and a brake disc 11 sleeved on the second shaft 611. A brake pad is provided between the pneumatic assembly 10 and the brake disc 11. A second bearing seat 607 is also provided on the second base frame 601 between the pneumatic brake 606 and the third coupling 608. The second shaft 611 passes through the first bearing seat 607. A third bearing seat 610 is also provided on the second base frame 601 between the fourth coupling 609 and the second winch 604. A third shaft 612 passes through the third bearing seat 610.

[0038] Specifically, the purpose of this invention is to provide a constant tension control device for large algae cultivation ropes under variable loads, preventing the ropes from being cut or broken by blades due to changes in force during offshore operations. Simultaneously, it can accurately measure the sag speed and angle of the rope under different force states during rope movement, providing a reference for practical offshore applications and ensuring the safety of the kelp seedling ropes during towing. The working principle of this invention is as follows: the cultivation rope 5 is released from the rope release machine 7 on the right side, and after passing through the second rope puller 6, the cultivation rope 5 has a certain tension, which is provided by the second rope puller 6. This tension is generated by the supporting pulley 3 and the second… The rope-pulling machine 6 has a 4-5 meter section in the middle (this is because the kelp is approximately 4-5 meters long, and during cutting, the kelp needs to be perpendicular to the cultivation rope 5 to prevent the rotating blade from cutting the kelp's shoulder and affecting its quality. One piece of kelp is suspended every 5 centimeters on the cultivation rope 5, with each piece weighing approximately 2.5 kg. Therefore, the load on this 5-6 meter section of rope is approximately 200-250 kg, resulting in a downward-curving shape under stress). The first rope-pulling machine 2 on the left is driven by a variable frequency motor 202. A torque sensor is installed between the variable frequency motor 202 and the first rope-pulling machine 2 to facilitate the measurement of dynamic torque during rope pulling. For details, please refer to [link to relevant documentation]. Figures 1 to 3 .

[0039] The second embodiment of the present invention relates to a method for maintaining constant tension of ropes used in large-scale algae cultivation under variable load, the process of which is as follows: Figure 8 As shown, the details are as follows:

[0040] Step 101: The second rope pulling machine 6 is used to simulate the random change of force value during the harvesting of large algae. The large algae cultivation rope 5 is in the gap of the second rope pulling machine 6 and is subjected to the pressure of the two traction discs on both sides. The large algae cultivation rope 5 and the second traction disc 9 on the second rope pulling machine 6 do not slide relative to each other. At this time, the electromagnetic clutch 605 is in the disengaged state, and the damping torque of the second rope pulling machine 6 is only provided by the pneumatic brake 606.

[0041] Specifically, the required load force is set either by a pre-set variable load curve in the PLC controller or manually on the touchscreen, according to... Figure 11 The pressure value is obtained by converting the theoretical load force to the pressure. This converted pressure value is then output through a model to achieve proportional control of the pneumatic brake 606, thereby controlling the output torque of the second rope-pulling machine 6. Specifically, when the set load force increases, the pressure increases, the pneumatic brake 606 tightens, and the output force of the second winch 604 increases; when the set load force decreases, the pneumatic brake 606 loosens, and the output force of the second winch 604 decreases. This simulates variable load during the kelp harvesting process. The control method is as follows: Figure 12 As shown.

[0042] More specifically, 1. The theoretical load force and pressure relationship calculation process is as follows: The second rope pulling machine 6 (which acts as a load) simulates the load during kelp harvesting. Its load is provided by the friction between the brake disc 11 and the pneumatic component 10. Its theoretical diagram is shown below. Figure 9 As shown, the calculation formula is:

[0043] F f =4πR 2 Pμ (1);

[0044] Among them, F f R is the frictional force exerted by the pneumatic assembly 10 on the brake disc 11, in N; R is the radius of the air cylinder in the pneumatic assembly 10, in m (the radius of the air cylinder in the pneumatic assembly 10 is 50 mm, i.e., 0.05 m); P is the air pressure in the air cylinder in the pneumatic assembly 10, in MPa (the normal maximum air pressure is 0.6 MPa, and it can reach 0.7 MPa in experiments); μ is the coefficient of friction (0.3-0.4, taken as 0.3).

[0045]

[0046] Among them, T f The load torque provided to the brake disc 11, N·m; F f ' is the frictional force per unit area of ​​the brake pad, in N, i.e. S A The contact area between the brake pads and the brake disc 11 is m. 2 (Approximately 3775.10 mm², or 0.0037751 m²); S is the domain of the brake pad on the brake disc 11, S = S1 + S2 + S3, x1, x2, y1, y2, y3 are 0.039, -0.039, -0.078, -0.09325, and -0.10875 respectively;

[0047] That is, T f =7.5130×10 -4 P, according to Figure 10 It can be seen that the torque of the brake disc 11 is controlled by controlling the air pressure. Then, the theoretical load force of the aquaculture rope 5 can be obtained by using the torque and the radius of the traction disc. The formula is:

[0048]

[0049] Wherein, F load is the load generated by the rope during the simulated harvesting process, in N; r2 is the radius of the second traction disc 9, in m (approximately 110 mm, or 0.11 m); r2' is the distance from the center of the aquaculture rope 5 to the arc of the second traction disc 9, theoretically calculated to be approximately the radius of the aquaculture rope 5, in m (in actual operation, the aquaculture rope 5 may not be attached to the traction disc), i.e. Assuming r2 is approximately 7-9 mm, or 0.007-0.009 m, then F 负载 ≈6.4214×10 -3 P reached 6.3134×10 -3 P, from which we obtain Figure 11 ,according to Figure 11 From this perspective, the error caused by r2' is very small, and the minimum load at 0.7 MPa is 450.96 kg, which is sufficient to meet the load requirements at harvest.

[0050] By working backwards from formulas (1), (2), and (3), the relationship between air pressure P and traction force F can be obtained:

[0051]

[0052] According to formula (4), for loads of 50kg, 100kg, and 200kg, the pneumatic brake 606 requires air pressures of approximately 0.0763-0.0776Mpa, 0.1526-0.1552Mpa, and 0.3052-0.3104Mpa, respectively.

[0053] 2. The calculation process for the relationship between speed and rotational speed is as follows: The torque and rotational speed on the traction disc can be obtained from the torque meter, and the theoretical speed formula of the rope is used to calculate it, i.e.:

[0054] v=n(r+r') (5)

[0055] Where v is the speed of the aquaculture rope 5, m / s; n is the rotational speed of the shaft, rpm; r is the radius of the traction disc, m; and r' is the distance between the arc of the traction disc and the center of the aquaculture rope 5, m.

[0056] 3. The calculation process of the load and torque relationship of the first rope pulling machine 2 is as follows: The relationship between the load and torque of the first rope pulling machine 2 is the same as that in formula (3), that is:

[0057] T1 = F 负载 (r1+r1') (6)

[0058] Where T1 is the torque of the first torque sensor 203, N·m; r1 is the radius of the traction disc of the first rope pulling machine 2, m; and r1' is the distance between the arc of the first traction disc 8 and the center of the breeding rope 5, m.

[0059] Step 102: The first rope pulling machine 2 is used to maintain the tension of the aquaculture rope 5 during the actual harvesting process. When the first rope pulling machine 2 pulls the aquaculture rope 5, in order to overcome the damping torque of the second rope pulling machine 6, the first rope pulling machine 2 rotates. At this time, when the first rope pulling machine 2 rotates, the first traction disc 8 opens and sends out the large algae aquaculture rope 5, thereby realizing that the aquaculture rope 5 is dragged with a dragging force. The tension of the first rope pulling machine 2 is set to a fixed value according to the required torque and the size of the winch.

[0060] Specifically, the first rope pulling machine 2 is used to maintain the tension of the aquaculture rope 5 during the actual harvesting process, to prevent the aquaculture rope 5 from being too loose and causing it to sag and be damaged by the harvesting cutter, and to prevent the aquaculture rope 5 from being too tight and causing it to break or stop due to overload; the cable traction device used eliminates the torque change caused by cable laying, and sets its tension to a fixed value according to the required torque and the size of the winch.

[0061] Currently, the tensile strength of the aquaculture rope 5 is ≤3000N. Therefore, the maximum tensile strength of the first rope pulling machine 2 is set to 3000N. When the required drag force for the damping of the second rope pulling machine 6 is greater than 3000N, the first rope pulling machine 2 maintains the set maximum tension. At this time, an error will be reported, indicating an abnormal operation, requiring manual intervention. When the required drag force for the damping of the second rope pulling machine 6 is less than 3000N, the first rope pulling machine 2, under the detection of the torque sensor, dynamically adjusts its relationship with the dragging speed through the PLC controller. The speed setting of this invention is ≤12m / min. When the dragging force decreases, the speed increases; when the dragging force increases, the speed decreases, maintaining relatively stable power. At the same time, the torque sensor detects and outputs torque and rotation speed in real time, records the rope dragging force and dragging speed, and the high-speed camera records the sag angle of the rope under different dragging forces.

[0062] More specifically, constant torque means keeping the motor's rotational torque constant, that is, requiring the PWM duty cycle to be increased to 100% as quickly as possible and kept constant, i.e., constant maximum torque control; the load characteristics are as follows: (1) when the load increases, the speed will decrease and the current will increase; (2) when the load decreases, the speed will increase and the current will decrease.

[0063] When the load force obtained from the torque sensor reading in the first rope-pulling machine 2 is less than the set value, the output torque of the variable frequency motor 202 is rapidly increased through adjustment using the PID control algorithm; when the load force obtained from the torque sensor reading in the first rope-pulling machine 2 is greater than the set value, the output torque of the variable frequency motor 202 is decreased through adjustment using the PID control algorithm, thus achieving constant tension control during the harvesting of large algae. For details, please refer to [link to relevant documentation]. Figure 13 ;

[0064] The logic control program in the PLC controller uses the PID algorithm, which is based on the proportional coefficient (K). p ), integral coefficient (K) i ) and differential coefficients (K d The proportional and derivative elements operate simultaneously to calculate the input deviation value using a functional relationship, and the result is used to control the output. When the feedback signal experiences a large deviation step, both the proportional and derivative elements work to suppress the feedback input change caused by this deviation step. An integral element is also considered for residual error elimination. The control principle block diagram is shown below. Figure 14As shown. The deviation e(t) between the setpoint r(t) and the measured load force f(t) is used as the input signal, and its expression formula is as follows: e(t) = r(t) - f(t); PID control uses the proportional, integral, and derivative of e(t) to form the control quantity through a linear combination, and its output signal is: After Laplace transform, the transfer function of the PID controller is:

[0065] Simulated instability: The pneumatic brake 606 is completely depressurized, the second rope puller 6 loses damping, and the first rope puller 2 detects through the torque sensor that the system's drag force is too low and the instantaneous drag speed is too high. The system automatically activates protection measures, the electromagnetic clutch 605 engages, and the servo motor 602 reverses to provide a certain torque to the second rope puller 6. At the same time, the speed of the variable frequency motor 202 of the first rope puller 2 decreases, the drag speed decreases, and the drag force decreases, keeping the breeding rope 5 in a relatively taut state. Meanwhile, the torque sensor detects and outputs torque and speed in real time, records the rope drag force and drag speed, and the high-speed camera records the sag angle and time of the rope under different drag forces, and records the system response time.

[0066] In further detail, the main principle of the constant tension and variable load joint control system for jointly regulating the first rope pulling machine 2 and the second rope pulling machine 6 is as follows: 1. Edit the control program of PLC and touch panel; 2. Start the variable frequency motor 202 under no-load (no air pressure in the air compressor, i.e., no load on the brake disc 11) to make the first rope pulling machine 2 and the second rope pulling machine 6 run stably. At this time, the first torque sensor 203 and the second torque sensor 603 can detect the starting torque of the first winch 204 and the second winch 604; 3. Input the load value on the touch panel. After the PLC calculates, it controls the air compressor to input the corresponding air pressure, so that the brake disc 11 outputs the corresponding load torque acting on the second winch 604. The second torque sensor 603 feeds back the actual torque to the PLC for minor adjustments to the air compressor; 4. At the same time, the first winch 204 is under load, the torque value output by the first torque sensor 203 increases and is fed back to the PLC. The PLC controls the variable frequency motor to increase the output torque. For details, please refer to [link to relevant documentation]. Figure 15 .

[0067] In summary, this invention designs a land-based constant tension experimental platform system that maintains relatively stable tension on the aquaculture rope with finished kelp under variable load conditions, or automatically pauses towing when the rope gets stuck, preventing the aquaculture rope 5 from being cut by a knife or broken due to excessive force due to sudden loss of force. At the same time, this device can accurately measure the sag speed and angle of the kelp aquaculture rope 5 under different force conditions during movement, providing a reference for practical applications at sea and ensuring that the kelp aquaculture rope 5 is safe and undamaged during towing.

[0068] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. All equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A method for maintaining constant tension of ropes used in large-scale algae cultivation under variable load, characterized in that: The method for controlling the constant tension of large algae cultivation rope under variable load is based on the device for controlling the constant tension of large algae cultivation rope under variable load. The device for controlling the constant tension of large algae cultivation rope under variable load includes a base plate (1). The base plate (1) is provided with a first rope pulling machine (2) for maintaining the tension of the cultivation rope (5) during the harvesting of large algae, a second rope pulling machine (6) for simulating the load force experienced by the first rope pulling machine (2) when dragging the cultivation rope (5) during the harvesting of large algae, and a rope releasing machine (7) located between the first rope pulling machine (2) and the second rope pulling machine (6) for winding the cultivation rope (5). The drive motors in the first rope pulling machine (2) and the second rope pulling machine (6) are both connected to a PLC controller. The second rope pulling machine (6) includes a second base frame (601), a servo motor (602), a second torque sensor (603), and a second winch (604) sequentially mounted on the second base frame (601). The second winch (604) is provided with a second traction disc (9). The output shaft of the servo motor (602) is connected to a second rotating shaft (611). The end of the second rotating shaft (611) near the servo motor (602) is provided with an electromagnetic clutch (605) located on the side of the third coupling (608). A pneumatic brake (606) for providing damping torque is provided between the electromagnetic clutch (605) and the third coupling (608). The pneumatic brake (606) includes a pneumatic component (10) mounted on the second base frame (601) and a brake disc (11) sleeved on the second rotating shaft (611). The method for controlling the constant tension of large algae cultivation ropes under variable load, applied to the second rope-pulling machine (6), includes the following steps: The second rope-pulling machine (6) is used to simulate the random changes in force during the harvesting of large algae. The large algae cultivation rope (5) is in the gap of the second rope-pulling machine (6) and is subjected to the pressure of the traction discs on both sides. There is no relative sliding between the large algae cultivation rope (5) and the second traction disc (9) on the second rope-pulling machine (6). At this time, the electromagnetic clutch (605) is in the disengaged state, and the damping torque of the second rope-pulling machine (6) is only provided by the pneumatic brake (606). Among them, the variable load curve preset in the PLC controller or manually in the touch screen is used to simulate the random changes in force during the harvesting of large algae. The required load force is set, and the corresponding pressure value is obtained according to the relationship between theoretical load force and pressure. The converted pressure value is output through the model quantity to realize the proportional control of the pneumatic brake (606), thereby controlling the output torque of the second rope pulling machine (6). When the set load force increases, the pressure increases, the pneumatic brake (606) tightens, and the output force of the second winch (604) increases. When the set load force decreases, the pneumatic brake (606) relaxes, and the output force of the second winch (604) decreases, thus realizing the variable load simulation in the process of harvesting kelp.

2. The method for controlling the constant tension of a large algae cultivation rope under variable load according to claim 1, characterized in that: A support pulley (3) is provided between the first rope pulling machine (2) and the second rope pulling machine (6) and is slidably connected to the aquaculture rope (5). The top of the support pulley (3) is provided with a cutting blade (4) for cutting large algae attached to the aquaculture rope (5).

3. The method for controlling the constant tension of a large algae cultivation rope under variable load according to claim 1, characterized in that: The first rope pulling machine (2) includes a first base frame (201), a variable frequency motor (202), a first torque sensor (203) and a first winch (204) installed sequentially on the first base frame (201). The output shaft of the variable frequency motor (202) is connected to the first output shaft of the first torque sensor (203) through a first coupling (205). A first rotating shaft (208) is connected to the second output shaft of the first torque sensor (203) through a second coupling (206). The end of the first rotating shaft (208) away from the first torque sensor (203) passes through the first winch (204). A first traction disc (8) is provided on the first winch (204).

4. The method for controlling the constant tension of a large algae cultivation rope under variable load according to claim 1, characterized in that: The end of the second rotating shaft (611) away from the servo motor (602) is connected to the first output shaft of the second torque sensor (603) via the third coupling (608). The second output shaft of the second torque sensor (603) is connected to the third rotating shaft (612) via the fourth coupling (609). The end of the third rotating shaft (612) away from the second torque sensor (603) passes through the second winch (604).

5. The method for controlling the constant tension of a large algae cultivation rope under variable load according to claim 1, characterized in that: The process of obtaining the corresponding pressure value based on the relationship between theoretical load force and pressure includes: The relationship between theoretical load force and pressure is determined using the following formula: ； Wherein, P is the air pressure in the pneumatic cylinder of the pneumatic assembly (10); For load capacity; The radius of the second traction disc (9); S is the distance from the center of the aquaculture rope (5) to the arc of the second traction disc (9), which is theoretically calculated to be approximately the radius of the aquaculture rope (5); A R is the contact area between the brake pads and the brake disc (11); R is the radius of the air cylinder in the pneumatic assembly (10); is the coefficient of friction; S is the domain of the brake pad on the brake disc (11); x and y are the axes with the center of the brake disc (11) as the origin, the horizontal axis as the X-axis, and the vertical axis as the Y-axis.

6. The method for controlling the constant tension of a large algae cultivation rope under variable load according to claim 3, characterized in that: The application to the first rope-pulling machine (2) includes the following steps: The first rope pulling machine (2) is used to maintain the tension of the aquaculture rope (5) during the actual harvesting process. When the first rope pulling machine (2) drags the aquaculture rope (5), in order to overcome the damping torque of the second rope pulling machine (6), the first rope pulling machine (2) rotates. At this time, when the first rope pulling machine (2) rotates, the first traction disc (8) opens and sends out the large algae aquaculture rope (5), thereby realizing that the aquaculture rope (5) is dragged with a dragging force. The first rope pulling machine (2) sets its tension to a fixed value according to the required torque and the size of the winch.

7. The method for controlling the constant tension of a large algae cultivation rope under variable load according to claim 6, characterized in that: The relationship between the dragging force and dragging speed of the first rope pulling machine (2) is dynamically adjusted by the PID control algorithm in the PLC controller. When the dragging force of the first rope pulling machine (2) decreases, the speed increases; when the dragging force increases, the speed decreases, keeping the power relatively stable. Also, when the load force obtained after the value conversion of the first torque sensor (203) in the first rope pulling machine (2) is less than the set value, the output torque of the variable frequency motor (202) is rapidly increased through the adjustment of the PID control algorithm. When the load force obtained after the value conversion of the first torque sensor (203) in the first rope pulling machine (2) is greater than the set value, the output torque of the variable frequency motor (202) is reduced through the adjustment of the PID control algorithm, thereby realizing constant tension control in the process of harvesting large algae.

8. The method for controlling the constant tension of a large algae cultivation rope under variable load according to claim 7, characterized in that: The dynamic adjustment of the relationship between the dragging force and dragging speed of the first rope-pulling machine (2) through the PID control algorithm in the PLC controller includes: The logic control program in the PLC controller adopts the PID control algorithm, which uses a proportional coefficient (PID) to control the PLC controller. ), integral coefficient ( ) and differential coefficients ( The function relationship is used to calculate the input deviation value, and the calculation result is used to control the output. When the feedback signal has a large deviation step, the proportional and derivative elements work simultaneously to suppress the feedback input change caused by this deviation step. At the same time, an integral element is added to eliminate the residual error. Setting value With the determination of load force deviation value As the input signal, its expression formula is as follows: ； PID control is The proportional, integral, and derivative terms are linearly combined to form the control quantity for control, and the output signal is: ； After Laplace transform, the transfer function of the PID controller is: 。

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