An Acceleration Smoothing Multi-Axis Synchronization Control Method Based on EtherCAT

Abstract

This invention belongs to the field of industrial automation and discloses an acceleration smoothing multi-axis synchronous control method based on EtherCAT. It constructs acceleration curves for acceleration and deceleration segments using Bézier curves, derives acceleration curve equations, and determines the existence of uniform velocity segments. Based on the acceleration curve equations of the acceleration and deceleration segments, it determines the existence of uniform acceleration and uniform deceleration segments. Based on the determination results, a seven-segment or five-segment S-shaped trajectory structure is constructed. The discrete values ​​of the displacement curves of each segment in the S-shaped trajectory structure are sampled during interpolation cycles to obtain the interpolation length for each interpolation cycle. This length is then executed by the slave servo driver written to the periodic synchronous position control mode by the EtherCAT master station. After each interpolation cycle, the error between the desired displacement and the actual displacement is calculated, and the Bézier curve is fine-tuned. This invention effectively improves the smoothness and compliance of the motion trajectory and can effectively solve the problem of vibration caused by changes in angular velocity during high-speed machining or machining of curved segments with multiple consecutive corners.

Description

Technical Field

[0001] This invention belongs to the field of industrial automation, specifically relating to an acceleration smoothing multi-axis synchronous control method based on EtherCAT. Background Technology

[0002] With the widespread application of multi-axis high-speed motion equipment in cutting machines, die-cutting machines, engraving machines, laser processing, and other fields, motion control systems have placed higher demands on trajectory smoothness, response accuracy, and path tracking performance. In industrial control, EtherCAT (Ethernet for Control Automation Technology) bus, with its high real-time performance, high bandwidth, and good scalability, has become one of the mainstream communication technologies for multi-axis synchronous control.

[0003] In EtherCAT Cyclic Synchronous Position Control (CSP) mode, the master controller sends the target position point to the servo drive at a fixed period (usually 1ms) to achieve periodic trajectory interpolation control. Traditional acceleration and deceleration algorithms often use segmented constant acceleration (discontinuous jerk) or standard S-shaped trajectory (segmented constant jerk) to construct the velocity trajectory. These trajectories have problems with sudden changes in jerk or discontinuous transitions in the acceleration and deceleration sections, which can easily cause mechanical shock and equipment vibration, especially in high-speed or curved section machining.

[0004] Furthermore, in situations with short paths or asymmetrical start and end speeds, traditional trajectory planning methods often employ fixed patterns to construct trajectory segment structures (such as five-segment or seven-segment structures), lacking the ability to adaptively adjust the trajectory structure. This results in low trajectory running efficiency, failure to fully utilize dynamic performance, and even issues such as overflow or insufficiency of the end-interpolation cycle step size, affecting trajectory accuracy and processing quality.

[0005] Some existing methods attempt to alleviate the above problems by improving interpolation resolution and optimizing velocity loops, but they fail to solve the problems of jerk continuity and adaptive trajectory structure construction from the perspective of trajectory ontology planning. Therefore, they still have defects such as insufficient smoothness and unstable dynamic response. Summary of the Invention

[0006] The purpose of this invention is to provide an acceleration smoothing multi-axis synchronous control method based on EtherCAT, which involves a jerk continuous trajectory planning method based on Bézier curve construction, applicable to smooth acceleration and deceleration interpolation control in EtherCAT periodic synchronous position mode.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An acceleration-smoothing multi-axis synchronous control method based on EtherCAT includes:

[0009] The acceleration and deceleration curves of the acceleration and deceleration segments are constructed using Bézier curves, and the equations of the acceleration curves are obtained. By integrating the equations of the acceleration curves one after another, the equations of the acceleration curve, velocity curve, and displacement curve are obtained.

[0010] Based on the displacement curve equations of the acceleration and deceleration segments, determine whether there is a uniform velocity segment. Based on the acceleration curve equations of the acceleration and deceleration segments, determine whether there is a uniform acceleration segment and a uniform deceleration segment. Based on the judgment results, construct a seven-segment or five-segment S-shaped trajectory structure.

[0011] The interpolation length for each interpolation cycle is obtained by sampling the discrete values ​​of the displacement curves of each segment in the S-shaped trajectory structure during the interpolation cycle, and then executed by the slave servo driver written into the cycle synchronization position control mode by the EtherCAT master station.

[0012] After each interpolation cycle, the error between the expected displacement and the actual displacement is calculated. If the cumulative error exceeds the threshold, the Bézier curve is compensated and adjusted. The acceleration curve, velocity curve, and displacement curve of the unfinished stage in the S-shaped trajectory structure are adjusted and the interpolation is completed.

[0013] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0014] Preferably, the Bézier curve is of order five, and the control points of the Bézier curve are constructed in a symmetrical distribution manner.

[0015] Preferably, determining whether a uniform velocity segment exists based on the displacement curve equations of the acceleration and deceleration segments includes:

[0016] Based on the displacement curve equations of the acceleration and deceleration phases, the displacements of the acceleration and deceleration phases are obtained.

[0017] Calculate the sum of the displacements of the acceleration segment and the deceleration segment. If the sum is greater than the total length of the given trajectory, then there is no uniform velocity segment; otherwise, there is a uniform velocity segment.

[0018] Preferably, the determination of whether a uniform acceleration segment and a uniform deceleration segment exist is based on the acceleration curve equations of the acceleration and deceleration segments. The process for determining whether a uniform acceleration segment exists is as follows:

[0019] Calculate the initial velocity to maximum speed Required speed increment and increase the speed. Compared with the segment of positive acceleration increase and the positive acceleration decrease segment The velocity increase obtained by successive integration of the acceleration curve Comparison: When the speed increment Less than or equal to the speed increase When this occurs, it indicates that the acceleration cannot reach its maximum. Otherwise, the acceleration will increase to the maximum acceleration. ;

[0020] If the acceleration cannot reach the maximum acceleration Therefore, the S-shaped trajectory structure does not include a uniform acceleration segment. Otherwise, determine that the S-shaped trajectory structure contains a uniform acceleration segment. .

[0021] Preferably, the determination of whether a uniform acceleration segment and a uniform deceleration segment exist is based on the acceleration curve equations of the acceleration and deceleration segments. The process for determining whether a uniform deceleration segment exists is as follows:

[0022] Calculate the maximum speed Final velocity Required speed increment and increase the speed Compared with the segment of increasing negative acceleration and negative acceleration decrease segment The velocity increase obtained by successive integration of the acceleration curve Comparison: When the speed increment Less than or equal to the speed increase When this occurs, it indicates that the acceleration cannot reach the maximum negative acceleration. Otherwise, the acceleration will increase to the negative maximum acceleration. ;

[0023] If the acceleration cannot reach the maximum negative acceleration Therefore, the S-shaped trajectory structure does not include a uniform deceleration section. Otherwise, it is determined that the S-shaped trajectory structure contains a uniformly decelerated segment. .

[0024] Preferably, the compensation adjustment of the Bézier curve includes:

[0025] Determine the current interpolation cycle's location within the S-shaped trajectory structure;

[0026] Take the control points of the Bézier curve in the trajectory segment where the acceleration and deceleration segments are located, as well as in the trajectory segment following the current trajectory segment.

[0027] Based on the direction and magnitude of the error, the control points of the selected Bézier curve are scaled or translated to obtain the control points of the compensated Bézier curve.

[0028] Preferably, the scaling or translation adjustment of the control points of the selected Bézier curve includes:

[0029] The cumulative error value is weighted using the error compensation coefficient, and the weighted result is superimposed onto the original control points of the Bézier curve to obtain the control points of the compensated Bézier curve.

[0030] The present invention provides an acceleration smoothing multi-axis synchronous control method based on EtherCAT. Compared with the prior art, its significant advantages are: it can effectively solve the acceleration shock caused by jerk change in the traditional S-shaped acceleration and deceleration method, so that the generated acceleration, velocity and displacement curves all have third-order continuity, effectively improving the smoothness and compliance of the motion trajectory. At the same time, it can effectively solve the problem of vibration caused by the change of corner speed in the machining of curve segments with multiple continuous corners at high speed. Attached Figure Description

[0031] Figure 1 This is a flowchart of an acceleration smoothing multi-axis synchronous control method based on EtherCAT according to the present invention;

[0032] Figure 2 This is a comparison of the original Beizer curve, the compensated curve, and the jerk trajectory of the traditional S-shaped algorithm under the same parameter conditions in the experiment of this invention.

[0033] Figure 3 This is a comparison of the original Beizer curve, the compensated curve, and the acceleration trajectory of the traditional S-curve algorithm under the same parameter conditions in the experiment of this invention.

[0034] Figure 4 This is a comparison chart of the original Beizer curve, the compensated Beizer curve, and the velocity trajectory of the traditional S-curve algorithm under the same parameter conditions in the experiment of this invention;

[0035] Figure 5 This is a comparison diagram of the original Beizer curve, the compensated curve, and the displacement trajectory of the traditional S-curve algorithm under the same parameter conditions in the experiment of this invention.

[0036] Figure 6 This is a magnified comparison of the original Beizer curve, the compensated curve, and the Jerk trajectory of the traditional S-shaped algorithm under the same parameter conditions in the experiment of this invention.

[0037] Figure 7 This is a magnified comparison of the Beizer original curve, the compensated curve, and the acceleration trajectory of the traditional S-curve algorithm under the same parameter conditions in the experiment of this invention.

[0038] Figure 8 This is a magnified comparison of the original Beizer curve, the compensated Beizer curve, and the velocity trajectory of the traditional S-curve algorithm under the same parameter conditions in the experiment of this invention.

[0039] Figure 9 This is a magnified comparison of the original Beizer curve, the compensated curve, and the displacement trajectory of the traditional S-shaped algorithm under the same parameter conditions in the experiment of this invention. Detailed Implementation

[0040] 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, and 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.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0042] To address the shortcomings of existing technologies, this embodiment proposes a scheme based on EtherCAT to construct a smooth jerk curve from the Bézier curve, thereby improving interpolation compliance and trajectory continuity. It also proposes an acceleration smoothing multi-axis synchronous control method based on EtherCAT.

[0043] The multi-axis synchronous control method proposed in this embodiment is suitable for high-precision trajectory interpolation control of each motion axis in multi-axis CNC equipment, and has good adaptability, especially in typical X-axis and Y-axis dual-axis linkage systems. The control method is mainly aimed at multi-axis industrial equipment platforms that include motion actuators (such as crossbeam carriages and bearing frames), drive units (such as AC servo motors), and control units (such as EtherCAT master controllers).

[0044] In this embodiment, the X and Y axes are controlled objects, driven by servo drive motors in periodic synchronous position mode. The motors complete precise positioning according to the position commands sent by the controller in each interpolation cycle, and simultaneously upload the current feedback information (encoder position, speed, torque, etc.) to the control unit.

[0045] The control unit is implemented by an EtherCAT master controller based on the SOEM protocol. The master controller integrates a human-machine interface module (such as a touch screen display), a network communication module (such as an Ethernet interface), and a data storage module (such as an SD card or USB flash drive interface). Users can load graphic path files through the interface to set and manage the cutting trajectory. After the path data is preprocessed by the main control board, it is sent to the corresponding servo slave station in real time via the EtherCAT network in the form of discrete position commands.

[0046] The multi-axis synchronous control method proposed in this embodiment is embedded in the aforementioned controller as the core part of the position command generation logic within the control cycle. Compared with traditional interpolation strategies, this method combines trajectory planning technology that constructs jerk curves from Bézier curves, which can significantly improve trajectory smoothness, reduce servo shock, and effectively solve the residual error and system jitter problems that occur at the end of the path or corners in traditional interpolation. It is particularly suitable for machining applications with variable cutting paths and high precision requirements.

[0047] like Figure 1 As shown in this embodiment, an acceleration smoothing multi-axis synchronous control method based on EtherCAT includes the following steps:

[0048] Step 1: Construct acceleration curves for the acceleration and deceleration segments using Bézier curves, and obtain the acceleration curve equations. By successively integrating the acceleration curve equations, obtain the acceleration curve equation, velocity curve equation, and displacement curve equation.

[0049] First, the initial and final positions are recorded in the controller, and then the total length of the given trajectory is calculated. At the same time, it provides initial velocity. Final velocity Maximum acceleration Maximum deceleration Maximum jerk and interpolation period Next, a jerk (acceleration) curve is constructed using a fifth-order Bézier curve, and the resulting jerk curve function is obtained. for:

[0050]

[0051] In the above formula, The first of the Bézier curves One control point, The fifth-order Bernstein function satisfies:

[0052]

[0053] in This represents the current moment within the total time domain of the trajectory. This is the starting time point of the current Bézier curve segment. The duration of the current trajectory segment. The normalization parameter is used to map the current time to the interval [0,1], which is then used for the calculation of Bernstein polynomial basis functions.

[0054] In this embodiment, the control points of the Bézier curve are constructed using a symmetrical distribution, wherein the control points during the acceleration phase are... Among them, control points and The control points during the deceleration phase are their negative mirror images, ensuring a smooth transition and symmetry in the Jerk curve within each segment. It should be noted that the selection of control points above is merely an illustrative representation of this embodiment and is not limited to this symmetrical structure. Those skilled in the art can adjust and optimize the number, location, or distribution of control points according to different application scenarios and performance requirements.

[0055] Next, the jerk curve is explicitly integrated to obtain the acceleration, velocity, and displacement curves in sequence, forming a trajectory with third-order continuity. The specific steps for integration are as follows:

[0056]

[0057]

[0058]

[0059] The obtained acceleration ,speed With displacement The curves exhibit third-order continuity (C² continuity) for generating smooth trajectories. This yields the acceleration, velocity, and displacement curves for the acceleration and deceleration segments. Specifically, the control points of the symmetrical Bézier curve for the acceleration segment are divided into an acceleration segment (positive jerk increase segment) and a deceleration segment (positive jerk decrease segment) for the second half. Similarly, the control points of the symmetrical Bézier curve for the deceleration segment are divided into an acceleration / deceleration segment (negative jerk increase segment) and a deceleration segment (negative jerk decrease segment) for the second half.

[0060] Step 2: Based on the displacement curve equations of the acceleration and deceleration segments, determine whether there is a uniform velocity segment. Based on the acceleration curve equations of the acceleration and deceleration segments, determine whether there is a uniform acceleration segment and a uniform deceleration segment. Based on the judgment results, construct a seven-segment or five-segment S-shaped trajectory structure.

[0061] The complete seven-segment S-shaped trajectory structure consists of the following segments: the forward jerk segment. Uniform acceleration segment positive jerk reduction segment Uniform speed segment Negative jerk increase segment Uniform deceleration section Negative jerk reduction segment Calculate as follows:

[0062]

[0063] in, It is a constant (preset) determined solely by the control points of the Bézier curve.

[0064] Because it is constructed using a symmetrical Bézier curve:

[0065]

[0066] During the uniform acceleration segment When it exists,

[0067]

[0068] in:

[0069]

[0070]

[0071] in, The velocity increase for the two jerk segments is due to the symmetrical structure. .

[0072]

[0073] in, It is a constant (preset) determined solely by the Bézier control point.

[0074] When the uniform acceleration segment does not exist .

[0075] When the uniform speed segment exists

[0076]

[0077] If the uniform speed segment does not exist .

[0078] in The total length of the trajectory. It is the sum of the displacement during the acceleration phase and the displacement during the deceleration phase.

[0079] , , Similarly, this embodiment will not be described in detail.

[0080] Determine the total length of the current given trajectory When determining the specific S-shaped trajectory structure, first, determine whether there is a uniform acceleration segment in the trajectory. The judgment steps include:

[0081] (1) Calculate the initial velocity Maximum achievable speed (Extract) the required velocity increment from the acceleration phase velocity curve and add it to the segment increased by the positive jerk. and positive jerk reduction segment The velocity increase obtained by successive integration of the acceleration curve Compare. When the speed increment Less than or equal to the speed increase When this occurs, it indicates that the acceleration cannot reach its maximum. Otherwise, the acceleration will increase to the maximum acceleration. .

[0082] (2) From the acceleration curve of the acceleration segment Extracting the maximum value If the maximum value If so, it is considered that the maximum acceleration can be achieved. Otherwise, it is considered that the maximum acceleration cannot be reached. The physical constraints of the constructed curve are verified. Step (2) is understood as the result of step (1) and is expressed using acceleration.

[0083] (3) If step (2) determines that the maximum acceleration cannot be reached Then it is assumed that the trajectory does not include a uniform acceleration segment. Set its duration to 0; otherwise, determine that the trajectory contains a uniform acceleration segment. .

[0084] Secondly, determine whether there is a uniform deceleration segment in the trajectory. The judgment steps include:

[0085] (1) Calculate the maximum achievable speed (Extracted from the deceleration phase velocity curve) to the final velocity Required speed increment and add it to the segment increased by the negative jerk. and negative jerk reduction segment The velocity increase obtained by successive integration of the acceleration curve Compare. When the speed increment Less than or equal to the speed increase When this occurs, it indicates that the acceleration cannot reach the maximum negative acceleration. Otherwise, the acceleration will increase to the negative maximum acceleration. .

[0086] (2) From the acceleration curve of the acceleration segment Extracting the maximum value If the maximum value It is then assumed that the maximum negative acceleration can be achieved. Otherwise, it is considered that the maximum negative acceleration cannot be achieved. The physical constraints of the constructed curve are verified. Step (2) is understood as the result of step (1) and is expressed using acceleration.

[0087] (3) If step (2) determines that the negative maximum acceleration cannot be reached Then it is assumed that the trajectory does not include a uniformly decelerated segment. Set its duration to 0; otherwise, determine that the trajectory contains a uniformly decelerated segment. .

[0088] Secondly, by calculating the total displacement generated during the acceleration and deceleration phases... Used to determine whether a uniform velocity segment exists. The steps include:

[0089] (1) Based on the displacement curve equations of the acceleration and deceleration sections, the displacements of the acceleration and deceleration sections are obtained.

[0090] (2) Calculate the sum of the displacements during the acceleration and deceleration phases. .

[0091] (3) If the sum Greater than the total length of the given trajectory Then there is no uniform speed segment. Otherwise, there is a uniform velocity segment. .

[0092] Based on whether there is a uniform acceleration segment Uniform speed segment Uniform deceleration section Generate four-, five-, or seven-segment patterns. Since the five-segment pattern is a balanced form, it is often the most common. Furthermore, add segments to the positive jerk. positive jerk reduction segment Negative jerk increase segment and negative jerk reduction segment Given the given curves, the curves for the uniform acceleration segment, uniform deceleration segment, and uniform velocity segment can be directly obtained. For example, in the uniform acceleration segment: the jerk curve is always 0, the acceleration curve is the maximum acceleration (constant value) at the end of the acceleration segment, the velocity curve is a linearly increasing function, and the displacement curve is a quadratic function; in the uniform deceleration segment: the jerk curve is always 0, the acceleration curve is the maximum deceleration (constant negative value) at the end of the acceleration segment, the velocity curve is a linearly decreasing function, and the displacement curve is a quadratic function; in the uniform velocity segment: both the jerk curve and the acceleration curve are always 0, the velocity curve is the maximum velocity (constant value) at the end of the deceleration segment, and the displacement curve is a linear function.

[0093] Step 3: By sampling the discrete values ​​of the displacement curves of each segment in the S-shaped trajectory structure through the interpolation cycle, the interpolation length of each interpolation cycle is obtained, and then executed by the slave servo driver written into the cycle synchronization position control mode by the EtherCAT master station.

[0094] In this embodiment, the generated displacement curve will be interpolated using the interpolation period. Discretization is performed to form a displacement interpolation point series, which is periodically sent to the EtherCAT slave servo driver to achieve smooth trajectory tracking.

[0095] Step 4: After each interpolation cycle, calculate the error between the expected displacement and the actual displacement. If the cumulative error exceeds the threshold, compensate and adjust the Bézier curve, adjust the jerk curve, acceleration curve, velocity curve and displacement curve of the unfinished stage in the S-shaped trajectory structure and complete the interpolation.

[0096] Before performing dynamic compensation, it is first determined which segment of the acceleration / deceleration trajectory the current interpolation cycle falls within. For already executed trajectory segments, the corresponding Bézier control points and curve segments remain unchanged without any modification. Only incremental compensation of control points is performed on subsequent trajectory segments that have not yet been executed. The specific process of incremental compensation is as follows:

[0097] After each interpolation cycle, the difference between the expected displacement and the actual displacement is calculated. The errors of each interpolation cycle are summed to obtain the cumulative error value. When the accumulated error exceeds a preset threshold, an error compensation operation is triggered, and the accumulated error is cleared to zero. Based on the error direction and magnitude, the control points of the Bézier curve are rescaled or shifted to compensate for trajectory deviation. In this embodiment, the adjustment of the Bézier curve control points uses a proportional compensation method, namely:

[0098]

[0099] in, This is the current control point location. To compensate for the control point positions, This is the error compensation coefficient. This adjustment method ensures that the Bézier curve maintains continuity and smoothness during the compensation process, avoids abrupt changes in trajectory, and guarantees the compliance and accuracy of the multi-axis system motion.

[0100] After adjusting the control points of the Bézier curve, there is no need to re-determine whether the uniform velocity segment, uniform acceleration segment, and uniform deceleration segment exist. Instead, directly update the corresponding acceleration curve, velocity curve, and displacement curve of the planned but not executed stages. After updating, re-execute step 3 and use step 4 for continuous monitoring to realign the trajectory with the target path and continue the subsequent interpolation process.

[0101] See Figures 2-9 To verify the effectiveness of the method of this invention, a simulation experiment was designed. MATLAB was used as the development environment for the simulation, with the interpolation period set to 1 ms, the total displacement of the trajectory planning set to 70 mm, the maximum system speed limited to 40 mm / s, the maximum acceleration limited to 50 mm / s², and the maximum jerk limited to 100 mm / s³. The time intervals of each acceleration / deceleration trajectory segment were automatically calculated based on the maximum jerk and maximum acceleration constraints. Both acceleration and deceleration phases used fifth-order Bézier curves to construct the jerk segments. To simulate error accumulation during servo execution, a small disturbance signal was introduced to construct actual displacement feedback. The accumulated error triggered the dynamic correction mechanism of the Bézier control points in this invention, locally reconstructing future unexecuted trajectory segments. The simulation results show that the jerk curve of the traditional S-shaped acceleration / deceleration algorithm exhibits trapezoidal or square wave characteristics at the transition points, with significant jumps in its derivative, resulting in inflection points and noticeable discontinuities in the acceleration curve. This further causes second-order discontinuities in the velocity curve, ultimately leading to a slight curvature abrupt change in the displacement curve. For high-speed or high-precision equipment, such curvature jumps can easily lead to mechanical vibration, tool impact, and increased tracking errors.

[0102] In the Bézier curve optimization method proposed in this invention, the accelerometer curve is smoothly constructed by a fifth-order Bézier function, possessing natural... Continuity. As can be seen from the simulation diagram, after adopting the method of the present invention, the acceleration curve presents a continuous and smooth waveform, without the significant peaks and abrupt changes found in the traditional S-curve; the acceleration curve achieves a smooth transition between the two jerk change segments, and the curve is more rounded and continuous; the velocity curve is also significantly smoother than that of the traditional method, and the continuity of the second derivative is better; the overall curvature distribution of the displacement curve is uniform, with no abrupt change points, demonstrating higher trajectory quality.

[0103] Furthermore, after introducing the dynamic error compensation mechanism of the Bézier control point, the corrected jerk, acceleration, and velocity curves still maintain good continuity and smoothness, without the step changes that may be introduced by error compensation in traditional methods, thus proving that the dynamic compensation mechanism of the present invention does not destroy the smoothness of the trajectory.

[0104] This invention can effectively solve the acceleration shock caused by jerk abrupt changes in the traditional S-shaped acceleration and deceleration method, so that the generated acceleration, velocity and displacement curves all have third-order continuity, effectively improving the smoothness and compliance of the motion trajectory. At the same time, it can effectively solve the vibration problem caused by the change of corner speed when the motor is machining at high speed or in curve segments with multiple continuous corners.

[0105] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for acceleration smoothing multi-axis synchronous control based on EtherCAT, characterized in that, The acceleration smoothing multi-axis synchronous control method based on EtherCAT includes: The acceleration and deceleration curves of the acceleration and deceleration segments are constructed using Bézier curves, and the equations of the acceleration curves are obtained. By integrating the equations of the acceleration curves one after another, the equations of the acceleration curve, velocity curve, and displacement curve are obtained. Based on the displacement curve equations of the acceleration and deceleration segments, determine whether there is a uniform velocity segment. Based on the acceleration curve equations of the acceleration and deceleration segments, determine whether there is a uniform acceleration segment and a uniform deceleration segment. Based on the judgment results, construct a seven-segment or five-segment S-shaped trajectory structure. The interpolation length for each interpolation cycle is obtained by sampling the discrete values ​​of the displacement curves of each segment in the S-shaped trajectory structure during the interpolation cycle, and then executed by the slave servo driver written into the cycle synchronization position control mode by the EtherCAT master station. After each interpolation cycle, the error between the expected displacement and the actual displacement is calculated. If the cumulative error exceeds the threshold, the Bézier curve is compensated and adjusted. The acceleration curve, velocity curve, and displacement curve of the unfinished stage in the S-shaped trajectory structure are adjusted and the interpolation is completed.

2. The acceleration smoothing multi-axis synchronous control method based on EtherCAT according to claim 1, characterized in that, The Bézier curve is of order five, and the control points of the Bézier curve are constructed in a symmetrical distribution manner.

3. The acceleration smoothing multi-axis synchronous control method based on EtherCAT according to claim 1, characterized in that, The determination of whether a uniform velocity segment exists based on the displacement curve equations of the acceleration and deceleration segments includes: Based on the displacement curve equations of the acceleration and deceleration phases, the displacements of the acceleration and deceleration phases are obtained. Calculate the sum of the displacements of the acceleration segment and the deceleration segment. If the sum is greater than the total length of the given trajectory, then there is no uniform velocity segment; otherwise, there is a uniform velocity segment.

4. The acceleration smoothing multi-axis synchronous control method based on EtherCAT according to claim 1, characterized in that, The process of determining whether a uniform acceleration segment and a uniform deceleration segment exist is based on the acceleration curve equations of the acceleration and deceleration segments. The process of determining whether a uniform acceleration segment exists is as follows: Calculate the initial velocity to maximum speed Required speed increment and increase the speed Compared with the segment of positive acceleration increase and the positive acceleration decrease segment The velocity increase obtained by successive integration of the acceleration curve Comparison: When the speed increment Less than or equal to the speed increase When this occurs, it indicates that the acceleration cannot reach its maximum. Otherwise, the acceleration will increase to the maximum acceleration. ; If the acceleration cannot reach the maximum acceleration Therefore, the S-shaped trajectory structure does not include a uniform acceleration segment. ; Otherwise, determine that the S-shaped trajectory structure contains a uniform acceleration segment. .

5. The acceleration smoothing multi-axis synchronous control method based on EtherCAT according to claim 1, characterized in that, The process of determining whether a uniform acceleration segment and a uniform deceleration segment exist is based on the acceleration curve equations of the acceleration and deceleration segments. The process of determining whether a uniform deceleration segment exists is as follows: Calculate the maximum speed Final velocity Required speed increment and increase the speed Compared with the segment of increasing negative acceleration and negative acceleration decrease segment The velocity increase obtained by successive integration of the acceleration curve Comparison: When the speed increment Less than or equal to the speed increase When this occurs, it indicates that the acceleration cannot reach the maximum negative acceleration. Otherwise, the acceleration will increase to the negative maximum acceleration. ; If the acceleration cannot reach the maximum negative acceleration Therefore, the S-shaped trajectory structure does not include a uniform deceleration section. ; Otherwise, determine that the S-shaped trajectory structure contains a uniformly decelerated segment. .

6. The acceleration smoothing multi-axis synchronous control method based on EtherCAT according to claim 1, characterized in that, The compensation adjustment of the Bézier curve includes: Determine the current interpolation cycle's location within the S-shaped trajectory structure; Take the control points of the Bézier curve in the trajectory segment where the acceleration and deceleration segments are located, as well as in the trajectory segment following the current trajectory segment. Based on the direction and magnitude of the error, the control points of the selected Bézier curve are scaled or translated to obtain the control points of the compensated Bézier curve.

7. The acceleration smoothing multi-axis synchronous control method based on EtherCAT according to claim 6, characterized in that, The scaling or translation adjustment of the control points of the selected Bézier curve includes: The cumulative error value is weighted using the error compensation coefficient, and the weighted result is superimposed onto the original control points of the Bézier curve to obtain the control points of the compensated Bézier curve.

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