Motion and vibration integrated control method for hot nozzle of space additive manufacturing equipment

Abstract

The invention relates to the technical field of space additive manufacturing, and particularly provides a motion and vibration integrated control method and device for a hot nozzle of space additive manufacturing equipment, and the method comprises the steps: obtaining an expected track signal and an actual track signal of the hot nozzle of the space additive manufacturing equipment, the expected track signal and the actual track signal are subtracted and then input into a PID controller, so that motion control force output by the PID controller is obtained; the LMS algorithm is improved to obtain an improved LMS algorithm; a disturbance signal of the hot nozzle and an offset distance caused by disturbance are obtained, and after iteration processing is conducted on the disturbance signal and the offset distance through an improved LMS algorithm, vibration suppression force is output; the hot nozzle is controlled according to the motion controller force and the vibration suppression force. Therefore, synchronous control over the hot nozzle is achieved by combining PID control and the improved LMS algorithm, trajectory tracking control can be improved, meanwhile, movement deviation of the hot nozzle is reduced, and vibration during movement is restrained.

Description

Technical Field

[0001] The present invention relates to the technical field of parameter estimation of battery simulation electrochemical models, and particularly relates to a method for integrated control of the movement and vibration of a hot nozzle of a space additive manufacturing device and a device for integrated control of the movement and vibration of a hot nozzle of a space additive manufacturing device. Background Art

[0002] Space additive manufacturing technology unifies the manufacturing environment and the application environment to achieve on-demand in-situ manufacturing, liberating the traditional mode of "ground manufacturing - transportation and assembly", thereby saving the uplink cost, reducing the launch pressure, and optimizing the internal storage space of the space station, and has broad application and development prospects.

[0003] Space Fused Deposition Modeling (FDM) technology is an important support for human's extended space activities. Restricted by the space environment and constrained by space resources, the collaborative working mode of each system of the space FDM additive manufacturing device is different from that on the ground, but the basic working principle is the same. Its forming system mainly includes a wire storage disk, a wire feeding mechanism, a hot nozzle, a hot bed substrate, and parts, etc. The basic working structure is shown as Figure 1 follows: Under the active driving of the wire feeding mechanism, high-performance thermoplastic polymer and its composite filaments are sent out by the wire feeding mechanism, enter the hot nozzle for heating, are melted and then extruded, and deposited on the hot bed substrate for forming; the actuator moves according to the path planning, drives the hot nozzle to move, so that the molten filaments are bonded layer by layer at the specified positions, and finally stacked and formed into a designed sample.

[0004] During the on-orbit operation of a space device, body disturbance sources such as high-speed rotors in attitude control flywheels, attitude adjustment thrusters, and solar panel drive mechanisms, and at the same time, multiple external disturbance sources such as microparticle flows and solar winds are superimposed, which will cause the space device itself to generate structural vibrations, and will also directly or indirectly affect the space additive manufacturing device carried by it through the transmission channel. At the same time, during the manufacturing process of the space additive manufacturing device, the hot nozzle is in a working state of high speed and low load, and starts and stops frequently during work, which is prone to dynamic load impact and inertial forces, thereby causing the movement trajectory of the hot nozzle to deviate. At the same time, in the microgravity environment, some low-frequency vibrations with slow attenuation are generated in the entire hot nozzle and its execution system.

[0005] Therefore, in the related technologies, there are problems of movement deviation and hot nozzle vibration caused by the frequent start and stop of the hot nozzle of the space additive manufacturing device during work and the external interference environment. Summary of the Invention

[0006] In order to solve one of the above technical problems, the present invention proposes the following technical solutions.

[0007] An integrated control method for the movement and vibration of a hot nozzle of a spatial additive manufacturing device according to an embodiment of the first aspect of the present invention includes the following steps: obtaining the desired trajectory signal and the actual trajectory signal of the hot nozzle of the spatial additive manufacturing device, subtracting the actual trajectory signal from the desired trajectory signal and inputting the result into a PID controller to obtain the movement control force output by the PID controller; improving the LMS (Least Mean Square) algorithm to obtain an improved LMS algorithm; obtaining the disturbance signal of the hot nozzle and the offset distance caused by the disturbance, and iteratively processing the disturbance signal and the offset distance through the improved LMS algorithm to output a vibration suppression force; and controlling the hot nozzle according to the movement controller force and the vibration suppression force.

[0008] In addition, the integrated control method for the movement and vibration of a hot nozzle of a spatial additive manufacturing device according to the above embodiment of the present invention may further have the following additional technical features.

[0009] According to an embodiment of the present invention, improving the LMS algorithm includes: improving the step size calculation method of the LMS algorithm, and specifically calculating the step size of the LMS algorithm through the following formula:

[0010]

[0011] where mu is the step size, a, b, and c are all parameters, a > 0.01, c < 5, and e is the offset distance.

[0012] According to an embodiment of the present invention, the actual trajectory signal and the offset distance are collected by a sensor.

[0013] An integrated control device for the movement and vibration of a hot nozzle of a spatial additive manufacturing device according to an embodiment of the second aspect of the present invention includes: a first acquisition module for obtaining the desired trajectory signal and the actual trajectory signal of the hot nozzle of the spatial additive manufacturing device, subtracting the actual trajectory signal from the desired trajectory signal and inputting the result into a PID controller to obtain the movement control force output by the PID controller; an improvement module for improving the LMS algorithm to obtain an improved LMS algorithm; a second acquisition module for obtaining the disturbance signal of the hot nozzle and the offset distance caused by the disturbance, and iteratively processing the disturbance signal and the offset distance through the improved LMS algorithm to output a vibration suppression force; and a control module for controlling the hot nozzle according to the movement controller force and the vibration suppression force.

[0014] The technical solution of the embodiment of the present invention combines PID control and an improved LMS algorithm to achieve synchronous control of the hot nozzle, which can improve trajectory tracking control while reducing the movement deviation of the hot nozzle and suppressing vibration during movement. Description of the Drawings

[0015] Figure 1 It is a schematic diagram of the working structure of an FDM additive manufacturing device.

[0016] Figure 2 It is a flowchart of the integrated control method for the movement and vibration of the hot nozzle of the spatial additive manufacturing device according to the embodiment of the present invention.

[0017] Figure 3 It is a block diagram of the integrated control strategy according to the embodiment of the present invention.

[0018] Figure 4 It is an effect diagram of trajectory tracking of a specific example of the present invention.

[0019] Figure 5 It is an effect diagram of suppressing vibration by the improved LMS algorithm (SHLMS algorithm) of a specific example of the present invention.

[0020] Figure 6 It is a block diagram of the structure of the integrated control device for the movement and vibration of the hot nozzle of the spatial additive manufacturing device according to the embodiment of the present invention. Detailed Embodiment

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] Figure 2 It is a flowchart of the integrated control method for the movement and vibration of the hot nozzle of the spatial additive manufacturing device according to the embodiment of the present invention.

[0023] As Figure 2 shown, the integrated control method for the movement and vibration of the hot nozzle of the spatial additive manufacturing device includes the following steps S1 to S4.

[0024] S1. Obtain the desired trajectory signal and the actual trajectory signal of the hot nozzle of the spatial additive manufacturing device, subtract the actual trajectory signal from the desired trajectory signal, and input the result into a PID controller to obtain the movement control force output by the PID controller.

[0025] Among them, the desired trajectory signal is given in advance, and the actual trajectory signal can be obtained by collecting through a sensor.

[0026] Specifically, when the spatial additive manufacturing equipment is working, obtain the desired trajectory signal of its thermal nozzle, collect its actual trajectory signal, input the difference obtained by subtracting the actual trajectory signal from the desired trajectory signal into the PID controller, and then the PID controller outputs a motion control force to the control object (thermal nozzle).

[0027] Thus, the PID controller is used to control the motion control loop, with the goal of reducing the deviation between the desired trajectory signal and the actual trajectory signal. The PID controller optimizes the response performance of the system by adjusting the proportional, integral, and differential coefficients.

[0028] S2. Improve the LMS algorithm to obtain an improved LMS algorithm.

[0029] Specifically, the traditional LMS (Least Mean Square) algorithm cannot simultaneously ensure a fast convergence speed and a small steady-state error. Therefore, in the embodiments of the present invention, the traditional LMS algorithm is improved. By coupling the error square term with a non-linear function, dynamic optimization of the step size is achieved, the error amplitude is converted into an energy form, and the adjustment weight when the error is large is strengthened.

[0030] S3. Obtain the disturbance signal of the thermal nozzle and the offset distance caused by the disturbance, and output a vibration suppression force after iteratively processing the disturbance signal and the offset distance through the improved LMS algorithm.

[0031] Among them, the disturbance signal is all external interferences received by the thermal nozzle during operation, which causes the thermal nozzle to vibrate, and then the motion trajectory deviates. The offset distance can be collected by a sensor.

[0032] Specifically, when the spatial additive manufacturing equipment is working, obtain the disturbance signal of its thermal nozzle, collect its offset distance, and use the improved LMS algorithm to iteratively process the disturbance signal and the offset distance to obtain a vibration suppression force for the control object (thermal nozzle), which acts on the thermal nozzle to generate a reverse suppression force in the opposite direction to the vibration direction to suppress the vibration force.

[0033] Thus, using the improved LMS algorithm to suppress the vibration of the thermal nozzle can simultaneously ensure a faster convergence speed and better steady-state performance.

[0034] S4. Control the thermal nozzle according to the motion controller force and the vibration suppression force.

[0035] Specifically, after obtaining the motion control force and the vibration suppression force, control the thermal nozzle according to both of them, realizing integrated control of motion and vibration, and can synchronously optimize the trajectory tracking accuracy and the vibration suppression efficiency.

[0036] Therefore, the integrated control method for the movement and vibration of the hot nozzle of the spatial additive manufacturing equipment according to the embodiments of the present invention combines PID control and an improved LMS algorithm to achieve synchronous control of the hot nozzle, which can improve the trajectory tracking control while reducing the movement deviation of the hot nozzle and suppressing the vibration during movement.

[0037] In one example, the improvement of the LMS algorithm in step S2 may include: improving the step size calculation method of the LMS algorithm, and specifically calculating the step size of the LMS algorithm through the following formula:

[0038]

[0039] where mu is the step size, a, b, and c are all parameters, a > 0.01, c < 5, and e is the offset distance.

[0040] Specifically, a controls the overall gain of the step size and determines the convergence speed boundary; b adjusts the slope of the nonlinear interval and affects the sensitivity of the step size change; c is used as a base constant to avoid the denominator from becoming zero and ensure numerical stability. Using the nonlinear characteristic of the hyperbolic tangent function, the tanh(b*e*e)+c function maps the error energy to the [0, 1) interval and has a saturation characteristic.

[0041] The improved LMS algorithm of the present invention introduces an intelligent step size adjustment mechanism through the nonlinear compression of error energy and parameter decoupling design, achieving an adaptive balance between the convergence speed (large step size) and the steady-state accuracy (small step size), and effectively solving the contradiction between the convergence speed, tracking speed, and convergence accuracy of the traditional fixed-step LMS algorithm. This algorithm has broad application prospects in the field of adaptive filtering, especially in occasions where fast response and high-precision steady-state performance are required.

[0042] Through the above steps, the integrated control of the movement and vibration of the hot nozzle is achieved, and the problems of movement deviation and nozzle vibration caused by frequent start-up and braking during the operation of the hot nozzle and the external interference environment are solved.

[0043] As Figure 3 shown, the present invention uses PID control for the movement of the hot nozzle and at the same time uses the improved LMS algorithm to perform vibration suppression control on the moving hot nozzle (generating a reverse suppression force to suppress vibration), combining the classical PID control and the variable-step LMS algorithm, and achieving the synchronous optimization of the trajectory tracking accuracy and the vibration suppression efficiency.

[0044] By comparing the trajectory diagrams of adding PID and no control trajectories, as Figure 4 shown, the role of the PID controller can be intuitively evaluated. The experimental results show that after adding the PID controller, the response speed of the system is faster, the steady-state error can be eliminated, the position accuracy is improved, and the stability is higher.

[0045] To verify the dynamic performance of the improved LMS algorithm (SHLMS in the figure) in the vibration control of the gantry space additive manufacturing equipment, a comparison of four algorithms, namely Fx-LMS, NLMS, SVSLMS, and SHLMS, shows that, as Figure 5 shown. It can be seen that the improved LMS algorithm of the present invention, i.e., the SHLMS algorithm, has a better vibration suppression effect than other variable-step Fx-LMS algorithms in this simulation experiment, verifying the effectiveness of this algorithm.

[0046] In summary, for the integrated motion and vibration control method of the hot nozzle of the space additive manufacturing equipment in the embodiments of the present invention, by combining the classical PID control and the variable-step Fx-LMS (SHLMS) algorithm to control the hot nozzle, the synchronous optimization of the trajectory tracking accuracy and the vibration suppression efficiency is achieved.

[0047] Corresponding to the integrated motion and vibration control method of the hot nozzle of the space additive manufacturing equipment in the above embodiments, the present invention also proposes an integrated motion and vibration control device for the hot nozzle of the space additive manufacturing equipment.

[0048] Figure 6 It is the structural block diagram of the integrated motion and vibration control device for the hot nozzle of the space additive manufacturing equipment in the embodiments of the present invention.

[0049] As Figure 6 shown, the integrated motion and vibration control device for the hot nozzle of the space additive manufacturing equipment includes a first acquisition module 10, an improvement module 20, a second acquisition module 30, and a control module 40.

[0050] The first acquisition module 10 is used to acquire the desired trajectory signal and the actual trajectory signal of the hot nozzle of the space additive manufacturing equipment, subtract the actual trajectory signal from the desired trajectory signal and input the result into the PID controller to obtain the motion control force output by the PID controller; the improvement module 20 is used to improve the LMS algorithm to obtain an improved LMS algorithm; the second acquisition module 30 is used to acquire the disturbance signal of the hot nozzle and the offset distance caused by the disturbance, and output the vibration suppression force after iterative processing of the disturbance signal and the offset distance by the improved LMS algorithm; the control module 40 is used to control the hot nozzle according to the motion controller force and the vibration suppression force.

[0051] It should be noted that for the specific implementation manner of the integrated motion and vibration control device for the hot nozzle of the space additive manufacturing equipment, reference can be made to the specific implementation manner of the integrated motion and vibration control method of the hot nozzle of the space additive manufacturing equipment above. To avoid redundancy, it will not be elaborated here in detail.

[0052] The integrated control device for the movement and vibration of the hot nozzle of the spatial additive manufacturing equipment according to the embodiment of the present invention combines PID control and an improved LMS algorithm to achieve synchronous control of the hot nozzle, which can improve trajectory tracking control while reducing the movement deviation of the hot nozzle and suppressing vibration during movement.

[0053] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. An integrated control method for the movement and vibration of a hot nozzle of a spatial additive manufacturing device, characterized in that, Including the following steps: Obtain the desired trajectory signal and the actual trajectory signal of the hot nozzle of the spatial additive manufacturing equipment, subtract the actual trajectory signal from the desired trajectory signal and input the result into a PID controller to obtain the motion control force output by the PID controller; Improve the LMS algorithm to obtain an improved LMS algorithm; Obtain the disturbance signal of the hot nozzle and the offset distance caused by the disturbance, and perform iterative processing on the disturbance signal and the offset distance through the improved LMS algorithm to output a vibration suppression force; Control the hot nozzle according to the motion controller force and the vibration suppression force.

2. The integrated control method for the movement and vibration of the hot nozzle of the spatial additive manufacturing equipment according to claim 1, characterized in that, Improving the LMS algorithm includes: Improve the step size calculation method of the LMS algorithm. Specifically, calculate the step size of the LMS algorithm through the following formula: where mu is the step size, a, b, and c are all parameters, a > 0.01, c < 5, and e is the offset distance.

3. The integrated control method for the movement and vibration of the hot nozzle of the spatial additive manufacturing equipment according to claim 1, characterized in that The actual trajectory signal and the offset distance are obtained by sensor acquisition.

4. An integrated control device for the movement and vibration of a hot nozzle of a spatial additive manufacturing device, characterized in that, Including: A first acquisition module for obtaining the desired trajectory signal and the actual trajectory signal of the hot nozzle of the spatial additive manufacturing equipment, subtracting the actual trajectory signal from the desired trajectory signal and inputting the result into a PID controller to obtain the motion control force output by the PID controller; An improvement module for improving the LMS algorithm to obtain an improved LMS algorithm; A second acquisition module for obtaining the disturbance signal of the hot nozzle and the offset distance caused by the disturbance, and performing iterative processing on the disturbance signal and the offset distance through the improved LMS algorithm to output a vibration suppression force; A control module for controlling the hot nozzle according to the motion controller force and the vibration suppression force.

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