Dynamic motion control method, system and equipment for electric movable caster

Abstract

The invention provides a dynamic motion control method, system and device for an electric movable caster, and relates to the technical field of dynamic motion control methods for electric movable casters, and the method comprises the steps: employing a time-varying load inertia method to add the initial rotational inertia and the additional equivalent inertia of the movable caster, and obtaining the real-time equivalent rotational inertia of the movable caster; a coulomb friction model is adopted to construct the real-time friction force of the movable caster, and a dynamic model is constructed to calculate the angular acceleration of rotation of the movable caster; when the real-time angular acceleration is smaller than the lower limit threshold value, the angular acceleration of the movable trundle is increased through feedforward compensation, and when the real-time angular acceleration is larger than the upper limit threshold value, the angular acceleration of the movable trundle is reduced through reverse braking. Real-time loads are combined, friction torque is accurately represented, and the limitation of a traditional fixed friction coefficient model is overcome; current control and motion response are associated, and accurate torque distribution is achieved.

Description

Technical Field

[0001] This invention relates to the technical field of dynamic motion control methods for electric swivel casters, specifically to a dynamic motion control method, system, and device for electric swivel casters. Background Technology

[0002] In applications of intelligent material handling equipment such as intelligent forklifts and medical beds such as surgical transfer beds, electric casters are key components for achieving precise movement, smooth steering, and reliable parking. These devices often operate under high dynamic loads, such as changes in patient posture on medical beds, loading and unloading of materials, and environments with high safety requirements. They have extremely stringent standards for the smoothness of movement, quietness, and lifespan of the equipment. If there is a lack of effective constraint on angular acceleration during the caster's startup phase, the motor torque may fluctuate drastically due to sudden load changes, causing an impact torque at the moment the wheel contacts the ground. This may lead to early fatigue damage to the bearings, thereby reducing the reliability and lifespan of critical medical or logistics equipment. Therefore, researching and implementing dynamic constraints on angular acceleration during the startup phase is of vital engineering significance for ensuring the operational stability, mechanical durability, and safety of high-end material handling and medical care equipment.

[0003] In existing technologies, dynamic motion control methods for electric swivel casters are typically based on a fixed moment of inertia model. This means that the moment of inertia of the caster and its load is treated as a constant throughout the entire motion process, ignoring the dynamic effects of actual load changes. Friction compensation often employs a simplified static Coulomb friction model, calculating friction torque based solely on a fixed friction coefficient and constant load, without considering the dynamic correlation between real-time angular velocity and load mass on friction characteristics. Regarding angular acceleration control, existing technologies generally use fixed current thresholds, lacking adaptive setting and dynamic monitoring mechanisms for real-time angular acceleration upper and lower limits. When the load changes abruptly or the motion state changes drastically, the fixed parameter model cannot accurately reflect the actual dynamic characteristics of the system, leading to a deviation between the calculated drive current and the theoretical requirements. This results in problems such as lag in angular acceleration response, overshoot, or untimely braking, increasing motor energy consumption and mechanical wear, and also restricting the smoothness and overall energy efficiency of the swivel caster's motion. Therefore, a dynamic motion control method for electric swivel casters is urgently needed.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a dynamic motion control method, system, and device for electric swivel casters to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A dynamic motion control method for an electric swivel caster, comprising the following steps: S1: If the movable caster is in an accelerated state, the real-time load mass of the movable caster is obtained in real time; S2: Based on the real-time load mass of the swivel caster, the additional equivalent inertia is calculated using the parallel axis transformation method. Based on the additional equivalent inertia, the initial rotational inertia of the swivel caster is added to the additional equivalent inertia using the time-varying load inertia method to obtain the real-time equivalent rotational inertia of the swivel caster. S3: Based on the real-time rotational angular velocity of the movable caster, the real-time frictional force of the movable caster is constructed using the Coulomb friction model. Based on the real-time equivalent rotational inertia and real-time frictional force of the movable caster, a dynamic model is constructed to calculate the angular acceleration of the movable caster. S4: Set the upper and lower thresholds for angular acceleration. When the real-time angular acceleration is less than the lower threshold, feedforward compensation is used to increase the angular acceleration of the swivel caster. When the real-time angular acceleration is greater than the upper threshold, reverse braking is used to reduce the angular acceleration of the swivel caster.

[0007] Furthermore, to determine whether the swivel caster is in an accelerated state, the specific steps are as follows: Using the current moment as the endpoint, a first window is constructed by tracing back the time length. Within the first window, the angular velocity of the movable caster is obtained, and a curve showing the change of angular velocity over time is plotted. The slope of the curve is calculated at each moment. When the slope of the curve is detected to be greater than 0 and continuously increasing, it is marked as the movable caster being in an acceleration state.

[0008] Furthermore, the specific steps for obtaining the initial moment of inertia of the movable caster itself are as follows: Applying a force to the electric caster, calculate the initial moment of inertia of the caster using Newton's second law: in, This indicates the force applied to the swivel caster; Indicates the radius of the swivel caster; This represents the coefficient of kinetic friction of the ground. Apply force At that time, the angular acceleration that causes the movable caster to rotate; This represents the initial moment of inertia.

[0009] Furthermore, the real-time equivalent moment of inertia of the movable caster is calculated using the time-varying load inertia method. The specific steps are as follows: Based on the real-time load mass of the swivel casters, the additional equivalent inertia is calculated using the parallel axis transformation method: in, Indicates the additional equivalent inertia; Indicates load quality; Indicates the turning radius of the swivel caster; Based on the additional equivalent inertia, the time-varying load inertia method is used to add the initial rotational inertia of the swivel caster to the additional equivalent inertia: in, This represents the equivalent moment of inertia of the movable caster.

[0010] Furthermore, the real-time frictional force of the movable caster accelerating to rotate is constructed using the Coulomb friction model. The specific steps are as follows: Based on the dynamic friction coefficient of the ground and the real-time rotational angular velocity, the real-time frictional force of the movable caster accelerating to rotate is constructed using the Coulomb friction model: in, Indicates real-time frictional force; It represents angular velocity.

[0011] Furthermore, the angular acceleration of the movable caster rotation is constructed using a dynamic model. The specific steps are as follows: Based on the real-time equivalent moment of inertia and real-time friction of the swivel caster, a dynamic model is constructed to calculate the angular acceleration of the swivel caster's rotation: in, This indicates the angular acceleration of the movable caster. Indicates the damping coefficient of the rotating caster; Indicates driving torque; This represents the motor torque constant; This indicates the current of the motor.

[0012] Furthermore, upper and lower threshold values ​​for angular acceleration are set according to the following formula: in, The upper limit threshold for angular acceleration; This indicates the maximum current the motor can support for the rotation of the movable casters; This represents the lower limit threshold of angular acceleration.

[0013] Furthermore, the real-time angular acceleration is compared with the upper and lower threshold values ​​to dynamically control the output current, specifically: when At this time, feedforward compensation is used to increase the motor current, thereby increasing the angular acceleration of the swivel caster, according to the formula: in, when At that time, Reset to ; Indicates the magnitude of the current after compensation; Indicates the compensation current; Indicates the target angular acceleration; Indicates the target angular velocity; when At this time, reverse braking is used to reduce the motor current: in, Indicates the current used for reverse braking; This indicates the current after reverse braking; when At that time, Reset to ,in, This indicates the minimum current required for the motor to support the rotation of the movable casters.

[0014] The present invention also provides a dynamic motion control system for an electric swivel caster, the control system being used to execute the above-described control method, comprising: The data acquisition module is used to obtain the real-time load mass of the swivel caster if the swivel caster is in an accelerated state. The inertia acquisition module is used to calculate the additional equivalent inertia based on the real-time load mass of the movable caster using the parallel axis transformation method. Based on the additional equivalent inertia, the time-varying load inertia method is used to add the initial rotational inertia of the movable caster to the additional equivalent inertia to obtain the real-time equivalent rotational inertia of the movable caster. The acceleration acquisition module is used to construct the real-time friction force of the movable caster based on the real-time rotational angular velocity of the movable caster using the Coulomb friction model. Based on the real-time equivalent rotational inertia and real-time friction force of the movable caster, a dynamic model is constructed to calculate the angular acceleration of the movable caster's rotation. The dynamic control module is used to set the upper and lower thresholds of angular acceleration. When the real-time angular acceleration is less than the lower threshold, feedforward compensation is used to increase the angular acceleration of the movable caster. When the real-time angular acceleration is greater than the upper threshold, reverse braking is used to reduce the angular acceleration of the movable caster.

[0015] The present invention also provides a dynamic motion control device for an electric swivel caster. The control device is used to execute the control method described above. The device includes a storage medium and a processor. The storage medium stores a computer program, and when the computer program is executed by the processor, it implements the control method as described in any one of the claims.

[0016] Compared with the prior art, the beneficial effects of the present invention are: By sensing the load mass under acceleration in real time and dynamically calculating the equivalent moment of inertia, the inherent defect of traditional fixed inertia models in adapting to load changes is overcome. Combined with a Coulomb friction model based on real-time angular velocity, precise dynamic compensation for system friction is achieved. By establishing a dynamic threshold for angular acceleration based on real-time system capabilities and adopting intelligent feedforward compensation and reverse braking strategies, the control system can sensitively respond to changes in working conditions and accurately correct motion deviations. This improves the motion control accuracy, dynamic response speed, and operational stability of electric swivel casters under variable load and variable speed scenarios. At the same time, by optimizing energy distribution, the system energy consumption is effectively reduced, and mechanical shock and wear caused by control inaccuracies are mitigated, thereby extending the service life of the equipment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall method flow of the present invention; Figure 2 This is a schematic diagram illustrating the changes in angular acceleration and current magnitude in this invention; Figure 3 This is a schematic diagram of the overall system of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0019] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0020] Example: Please see Figures 1-2 The present invention provides a technical solution: A dynamic motion control method for an electric swivel caster, comprising the following steps: S1: If the movable caster is in an accelerated state, the real-time load mass of the movable caster is obtained in real time; To determine if the swivel casters are in an accelerated state, the specific steps are as follows: Using the current moment as the endpoint, a first window is constructed by tracing back the time length. Within the first window, the angular velocity of the movable caster is obtained, and a curve showing the change of angular velocity over time is plotted. The slope of the curve is calculated at each moment. When the slope of the curve is detected to be greater than 0 and continuously increasing, it is marked as the movable caster being in an acceleration state.

[0021] Within a defined first window, the instantaneous slope of the angular velocity-time curve is continuously calculated and monitored at each moment. An acceleration state is determined only when both of the following conditions are met: First, the first derivative calculated for all moments of the curve is greater than zero, confirming a continuous increase in angular velocity, rather than uniform or decelerating motion. Second, these derivative values ​​themselves exhibit a monotonically increasing trend with time. This means that the rate of increase in angular velocity is also accelerating, i.e., the curve is becoming increasingly steep, corresponding to a positive derivative of angular acceleration. Through this dual judgment, the critical moment when the system's inertial load effect changes most drastically and requires dynamic compensation and control intervention can be more accurately located.

[0022] In practical applications of swivel casters, such as intelligent handling equipment and medical beds, the acceleration phase is often the most challenging and unstable stage. In a constant and stable state, the system load and motion parameters are relatively constant, making control relatively simple. However, during acceleration, the load mass may change suddenly, causing the moment of inertia to change in real time, which in turn affects the angular acceleration and overall motion response. If the control is not handled properly at this time, problems such as weak acceleration, shaking, or overshoot may occur, directly affecting motion stability, energy efficiency, and equipment lifespan. Therefore, focusing on dynamic control during acceleration can more effectively cope with time-varying loads and disturbances in practical applications, improving system adaptability and reliability.

[0023] S2: Based on the real-time load mass of the swivel caster, the additional equivalent inertia is calculated using the parallel axis transformation method. Based on the additional equivalent inertia, the initial rotational inertia of the swivel caster is added to the additional equivalent inertia using the time-varying load inertia method to obtain the real-time equivalent rotational inertia of the swivel caster. The specific steps for obtaining the initial moment of inertia of the movable caster are as follows: Applying a force to the electric caster, calculate the initial moment of inertia of the caster using Newton's second law: in, This indicates the force applied to the swivel caster; Indicates the radius of the swivel caster; This represents the coefficient of kinetic friction of the ground. Apply force At that time, the angular acceleration that causes the movable caster to rotate; This represents the initial moment of inertia.

[0024] In the above process, by applying a known force to the caster system and measuring its dynamic response, the inherent rotational inertia of the caster body is directly identified, thereby eliminating the uncertainty of initial inertia caused by theoretical modeling errors or manufacturing tolerances. This method will reduce the driving torque. Compared with the measured frictional resistance torque The difference is directly related to the resulting angular acceleration. Through inertia The correlation established a causally clear physical identification model, ensuring the accuracy of the obtained data. The value truly reflects the actual inertial characteristics of a specific caster under specific ground conditions, rather than a rough theoretical estimate. With this high-precision initial inertia as the benchmark, the subsequent dynamic compensation of time-varying load inertia has solid reliability, fundamentally improving the initial accuracy of the system model and effectively avoiding problems such as torque calculation deviation, unsmooth acceleration, or decreased stability caused by the propagation and amplification of the benchmark inertia error throughout the control chain. The initial moment of inertia characterizes the rotation of a caster wheel; its physical meaning is the amount of rotational inertia the caster wheel uses to resist changes in angular acceleration. Reflecting the driving torque, it drives the casters to rotate in the positive direction. To characterize the ground frictional resistance torque and suppress the rotation process, a direct causal relationship for calculating the moment of inertia is established by correlating the difference between the driving torque and the frictional resistance torque with angular acceleration. and or There is a positive correlation; as the driving torque or caster radius increases, a higher moment of inertia is required to maintain the same angular acceleration. and or The correlation is inverse; when the ground friction coefficient increases or the measured angular acceleration increases, the calculated value of the equivalent moment of inertia decreases.

[0025] The coefficient of dynamic friction is derived from a database of empirical values ​​for the coefficients of friction of common floor materials. For example, the coefficient of dynamic friction is approximately 0.6 to 0.8 for smooth epoxy flooring, approximately 0.7 to 0.9 for dry asphalt pavement, and approximately 0.5 to 0.7 for carpet. When the casters are activated, the corresponding coefficient of dynamic friction will be selected according to the type of floor.

[0026] The real-time equivalent moment of inertia of the movable caster is calculated using the time-varying load inertia method. The specific steps are as follows: Based on the real-time load mass of the swivel casters, the additional equivalent inertia is calculated using the parallel axis transformation method: in, Indicates the additional equivalent inertia; Indicates load quality; Indicates the turning radius of the swivel caster; In the above process, by using the parallel axis transformation method in real time to calculate the additional equivalent inertia caused by the load mass and dynamically superimposing it with the inertia of the caster itself, this technical solution realizes the time-varying online identification and compensation of the total rotational inertia of the system. It effectively solves the "inertia mismatch" problem of the traditional fixed inertia model when the load changes dynamically, enabling the control system to accurately sense and respond to the inertia changes caused by the load mass and radius. It not only significantly suppresses the angular acceleration overshoot, response oscillation or jitter caused by sudden changes in inertia or inaccurate estimation, but also greatly improves the dynamic control accuracy and motion stability of the drive system under different load conditions. In particular, by introducing the radius square term, the system can more sensitively capture the nonlinear amplification effect of load distribution changes on inertia, so as to maintain stable and smooth acceleration performance in complex application scenarios, and enhance the adaptive ability and overall robustness of the electric movable caster to dynamic loads. The additional equivalent moment of inertia caused by the load mass is characterized by its physical meaning as the quantified value of the inertial effect of the load mass relative to the caster's rotation axis. By calculating the additional inertia in real time and dynamically correcting the total moment of inertia model, the control system can adapt to the time-varying characteristics of the load mass and suppress angular acceleration overshoot or jitter caused by inertial mismatch. The mass directly affects the magnitude of the added inertia; the greater the mass, the more significant the load inertia effect, and the greater the radius of rotation. The square relationship shows that small changes in caster size or load distribution radius can significantly amplify the added inertia. By quantifying the coupling relationship between mass and radius, the dynamic contribution of load distribution to rotational inertia can be achieved. and or All are positively correlated, and the square relationship of the radius leads to a nonlinear enhancement of its effect on the additional inertia.

[0027] Based on the additional equivalent inertia, the time-varying load inertia method is used to add the initial rotational inertia of the swivel caster to the additional equivalent inertia: in, This represents the equivalent moment of inertia of the movable caster.

[0028] In the above process, the initial rotational inertia of the movable caster is measured in real time using the time-varying load inertia method. Additional equivalent inertia calculated based on load mass The total equivalent moment of inertia is obtained by linear superposition. This technology precisely solves the "system inertial drift" problem in scenarios with real-time load changes. The control system no longer operates based on a fixed or empirical inertia value, but instead obtains comprehensive inertial parameters that reflect the current actual load state. This ensures that the dynamic model of the drive system (especially the model used to calculate angular acceleration) remains highly consistent with the actual physical system, fundamentally avoiding torque control errors caused by inertial parameter mismatch. The controller can instantly detect sudden increases or changes in load distribution. The increased torque and corresponding output effectively suppressed weak acceleration, sluggish response, or overshoot oscillation; conversely, when the load decreased, it also avoided shaking or uneven acceleration caused by excessive torque, significantly improving the control accuracy, dynamic response speed, and motion stability of the electric swivel casters under different load conditions, and enhancing the system's adaptability and robustness to complex application environments. The equivalent rotational inertia of the caster wheel is characterized by its physical meaning as the dynamic superposition of the initial inertia and the load-added inertia. It reflects the comprehensive inertial characteristics of the caster system under the influence of load changes. By superimposing the initial inertia and the added inertia in real time, the total rotational inertia of the system is dynamically updated, solving the inertial mismatch problem under time-varying load scenarios and ensuring the accuracy of angular acceleration control and the stability of motor torque output. Characterizing the inherent inertia of the caster itself, it is the fundamental component of the equivalent inertia. The inertial contribution of the load mass distribution is characterized as a dynamic component that changes in real time with the load mass and distribution radius. A direct coupling relationship between the initial characteristics and the dynamic influence of the load is established through a linear superposition rule. and or Both are strictly positively correlated; an increase in either variable leads to a synchronous increase in the total equivalent inertia, and their contributions to the total inertia are independent superposition modes.

[0029] S3: Based on the real-time rotational angular velocity of the movable caster, the real-time frictional force of the movable caster is constructed using the Coulomb friction model. Based on the real-time equivalent rotational inertia and real-time frictional force of the movable caster, a dynamic model is constructed to calculate the angular acceleration of the movable caster. The real-time frictional force of the movable caster during accelerated rotation is constructed using the Coulomb friction model. The specific steps are as follows: Based on the dynamic friction coefficient of the ground and the real-time rotational angular velocity, the real-time frictional force of the movable caster accelerating to rotate is constructed using the Coulomb friction model: in, Indicates real-time frictional force; It represents angular velocity.

[0030] In the above process, the frictional torque is constructed in real time using the Coulomb friction model. This achieves high-precision online estimation and compensation of dynamic frictional resistance during caster rotation. The model directly correlates the frictional torque with the normal force. radius and real-time angular velocity Linear correlation accurately quantifies the dynamic characteristics of frictional resistance as a function of load mass, ground conditions, and motion state, effectively avoiding problems such as sluggish acceleration, steady-state speed error, or inconsistent response caused by uncompensated friction. Furthermore, by introducing angular velocity... As a modulation factor, the model also better describes the speed-dependent dynamic friction characteristics; This describes the real-time frictional torque generated when the caster wheel accelerates. Its physical meaning is a quantified value of the resistance effect of ground friction on the dynamic rotation of the caster wheel. By accurately constructing a frictional torque model, the loss of driving torque due to friction can be compensated in real time, reducing angular velocity control errors. The normal force exerted by the load on the ground is the basis for determining the amplitude of the friction force. Converting linear frictional force into torque, increasing the radius directly increases the frictional torque. Characterizing the dynamic friction effect and reflecting the modulation characteristics of friction intensity by rotational speed. It is strictly positively correlated with all independent variables; an increase in any parameter leads to a synchronous linear increase in friction torque.

[0031] The angular acceleration of the movable caster rotation is constructed using a dynamic model. The specific steps are as follows: Based on the real-time equivalent moment of inertia and real-time friction of the swivel caster, a dynamic model is constructed to calculate the angular acceleration of the swivel caster's rotation: in, This indicates the angular acceleration of the movable caster. Indicates the damping coefficient of the rotating caster; Indicates driving torque; This represents the motor torque constant; This indicates the current of the motor.

[0032] In the above process, by integrating the real-time equivalent moment of inertia With dynamic friction torque It calculates angular acceleration in real time based on an accurate dynamic model, and when load changes cause... As acceleration increases, the model automatically predicts and compensates for the natural decay trend of acceleration, maintaining a consistent response; simultaneously, it dynamically subtracts... and Equal resistance terms ensure the drive current Every increment can be accurately converted into effective acceleration boost, rather than being absorbed by friction and damping. This enables the system to always output angular acceleration commands that precisely match the current physical state when facing load disturbances, changes in ground friction, or speed boosts, thereby significantly suppressing speed overshoot, oscillation, or response delay. The angular acceleration characterizes the swivel caster, and its physical meaning is the dynamic response rate of the net effect of the motor driving torque and friction damping torque to the rotational state. By dynamically balancing the driving torque and the resistance torque, the change in angular acceleration is calculated in real time to achieve high-precision torque closed-loop control and suppress speed fluctuations caused by load disturbances. As the active driving force source, it is positively correlated with angular acceleration, through and The linear relationship between the control input and the motor's electrical parameters reflects the coupling characteristics of the motor's electrical parameters to its mechanical response. and Together they characterize rotational drag and suppress the growth of angular acceleration. This reflects the attenuation effect of system inertia on acceleration; as inertia increases, the angular acceleration response slows down. and There is a strict positive correlation; an increase in driving torque directly increases angular acceleration. and , , , Both are negatively correlated; an increase in drag parameter or inertia will suppress angular acceleration.

[0033] In the above embodiments, the dependent variable angular acceleration is given. With independent variable The 20 sets of data reflect the relationship between angular acceleration and current variation, as shown in Table 1: Table 1: Relationship between angular acceleration and current As can be seen from Table 1 above, fixed , , , , As the current increases, the angular acceleration of the movable caster gradually increases, showing a linear relationship.

[0034] S4: Set the upper and lower thresholds for angular acceleration. When the real-time angular acceleration is less than the lower threshold, feedforward compensation is used to increase the angular acceleration of the swivel caster. When the real-time angular acceleration is greater than the upper threshold, reverse braking is used to reduce the angular acceleration of the swivel caster.

[0035] The upper and lower threshold values ​​for angular acceleration are set according to the following formula: in, The upper limit threshold for angular acceleration; This indicates the maximum current the motor can support for the rotation of the movable casters; This represents the lower limit threshold of angular acceleration.

[0036] The coefficient of 0.7 was chosen in the above process based on the consideration of balancing performance, safety and efficiency in engineering practice. On the one hand, this coefficient ensures the lower limit of actual angular acceleration. With the theoretical limit A 30% safety margin is maintained, which is sufficient to absorb dynamic uncertainties not covered in the system model, such as instantaneous frictional changes, sensor noise, and sudden changes in load distribution. This effectively avoids frequent oscillations or "fluttering" of control commands near the threshold boundary, ensuring the smoothness and stability of control. On the other hand, a ratio of 0.7 also means that the system can still maintain a high dynamic response capability under most operating conditions, without excessive sacrifice of acceleration performance due to an overly conservative protection threshold setting. It balances response agility and operational robustness well. As a proven compromise coefficient, 0.7 can provide a reliable and effective safety buffer for the dynamic control system without excessively limiting performance.

[0037] The upper limit threshold of angular acceleration is dynamically calculated and set based on real-time system parameters. and lower threshold A dynamic safety boundary, adaptive to load, friction, and motor capability, was established, with an upper threshold value. It reflects in real time the theoretical acceleration limit that the motor can achieve at its maximum output under the current load, friction, and inertia, while the lower limit threshold... This creates an "active protection zone." When the real-time acceleration of the system drops below this value due to a sudden increase in load inertia or increased friction, a compensation mechanism is triggered to prevent the system response from being too slow, sluggish, or "stuck," thereby maintaining basic motion. This effectively avoids insufficient protection or performance waste caused by fixed parameters, ensuring that the electric casters can operate safely, stably, and efficiently under various load conditions. The theoretical upper limit threshold characterizing angular acceleration, its physical meaning is the limiting angular acceleration that the system can achieve after overcoming frictional resistance when the motor outputs maximum driving torque. The actual lower limit threshold characterizing angular acceleration is determined by proportional constraints. Setting a safe operating range means establishing a dynamic protection reference value to suppress inertial shocks and energy loss. Define the physical limits of the system, combined with Limiting the range of acceleration fluctuations avoids control instability caused by motor overload or sudden frictional changes, thereby improving motion smoothness and reliability. Reflects the loss of driving force due to load friction, and negative correlation The amplification effect of system inertia on acceleration suppression leads to its increase. Reduced by dynamic binding with a scaling factor of 0.7. This ensures that the threshold setting is synchronized with the physical constraints in real time. and , Strictly positive correlation and , , , as well as Strictly negative correlation.

[0038] The real-time angular acceleration is compared with the upper and lower threshold values ​​to dynamically control the output current. Specifically: when At this time, feedforward compensation is used to increase the motor current, thereby increasing the angular acceleration of the swivel caster, according to the formula: in, when At that time, Reset to ; Indicates the magnitude of the current after compensation; Indicates the compensation current; Indicates the target angular acceleration; Indicates the target angular velocity; In the above process, a feedforward compensation current is introduced. And the real-time acceleration is below the lower threshold. The dynamic superposition of current onto the motor control current overcomes the inhibitory effect of system resistance and inertia on acceleration performance, thereby significantly improving dynamic response speed and eliminating acceleration lag. When insufficient actual angular acceleration is detected, the current is adjusted based on the target speed. Target acceleration Real-time inertia and friction The precise feedforward model directly calculates the "extra" current required to achieve the expected dynamic response, enabling the system to quickly escape the "acceleration slump" state caused by increased resistance or sudden load changes, by setting a current upper limit. The rigid cutoff protection ensures that performance improvements are always within the safe physical limits of the motor and drive, significantly reducing response time and steady-state error during acceleration. This allows the electric swivel casters to exhibit more agile, precise, and stable dynamic characteristics when faced with load changes or when rapid start-stop is required.

[0039] The feedforward compensation current component represents the current increment pre-calculated based on the target motion parameters and system dynamic characteristics. The real-time drive current after compensation is represented by the motor control current value dynamically adjusted through the feedforward compensation mechanism. Feedforward compensation actively offsets the losses in drive torque caused by damping, friction, and inertial resistance, thereby improving the angular acceleration response speed in real time. It reflects the current demand corresponding to the damping torque. Reflects the current demand corresponding to frictional resistance. The current demand, which characterizes the inertial torque, is positively correlated with the rate of change of the target angular acceleration. and Negative correlation: increasing the motor torque constant can reduce the current required for the same torque. At that time, forced truncation to This creates a piecewise linear relationship to protect the electric swivel casters.

[0040] when At this time, reverse braking is used to reduce the motor current: in, Indicates the current used for reverse braking; This indicates the current after reverse braking; when At that time, Reset to ,in, This indicates the minimum current required for the motor to support the rotation of the movable casters.

[0041] In the above process, a reverse braking current is introduced. And the real-time angular acceleration exceeds the upper limit threshold Dynamically reduce the total motor current It precisely counteracts excess drive torque, effectively preventing the system from becoming unstable due to excessive acceleration. This is achieved when the actual angular acceleration is detected to be close to or exceeds the theoretical physical limit. At that time, based on the current friction With damping The drag torque, calculated using negative current to determine the "braking" current required to balance excess driving force, is a model-based reverse compensation that, compared to traditional switching or strong proportional limiting, more smoothly suppresses overshoot and avoids speed oscillations and mechanical shocks. This is achieved by setting a lower current limit. Protection ensures that the system maintains a minimum controllable current under any circumstances, preventing accidental stall or runaway. The reverse braking current component represents the current reduction value based on the reverse cancellation requirement caused by friction and damping torque. Characterized by the real-time drive current after reverse braking, its physical meaning is the motor control current value dynamically adjusted through the reverse braking mechanism. and Both represent the rotational resistance torque; as their absolute value increases, a stronger reverse braking current is required to counteract the driving torque. The absolute values ​​are positively correlated. The actual value and Negative correlation: When the motor torque constant increases, the amplitude of the reverse braking current decreases. and Negative correlation, the superposition of reverse braking current reduces the total drive current, when At that time, Reset to .

[0042] Please see Figure 3 The present invention also provides a dynamic motion control system for an electric swivel caster, the control system being used to execute the above-described control method, comprising: The data acquisition module is used to obtain the real-time load mass of the swivel caster if the swivel caster is in an accelerated state. The inertia acquisition module is used to calculate the additional equivalent inertia based on the real-time load mass of the movable caster using the parallel axis transformation method. Based on the additional equivalent inertia, the time-varying load inertia method is used to add the initial rotational inertia of the movable caster to the additional equivalent inertia to obtain the real-time equivalent rotational inertia of the movable caster. The acceleration acquisition module is used to construct the real-time friction force of the movable caster based on the real-time rotational angular velocity of the movable caster using the Coulomb friction model. Based on the real-time equivalent rotational inertia and real-time friction force of the movable caster, a dynamic model is constructed to calculate the angular acceleration of the movable caster's rotation. The dynamic control module is used to set the upper and lower thresholds of angular acceleration. When the real-time angular acceleration is less than the lower threshold, feedforward compensation is used to increase the angular acceleration of the movable caster. When the real-time angular acceleration is greater than the upper threshold, reverse braking is used to reduce the angular acceleration of the movable caster.

[0043] The present invention also provides a dynamic motion control device for an electric swivel caster. The control device is used to execute the above-described control method and includes a storage medium and a processor. The storage medium stores a computer program, and when the computer program is executed by the processor, it implements the control method as described in any one of the claims.

[0044] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0045] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0046] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0047] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for dynamic motion control of an electric swivel caster, characterized in that the steps include... include: S1: If the movable caster is in an accelerated state, the real-time load mass of the movable caster is obtained in real time; S2: Based on the real-time load mass of the swivel caster, the additional equivalent inertia is calculated using the parallel axis transformation method. Based on the additional equivalent inertia, the initial rotational inertia of the swivel caster is added to the additional equivalent inertia using the time-varying load inertia method to obtain the real-time equivalent rotational inertia of the swivel caster. S3: Based on the real-time rotational angular velocity of the movable caster, the real-time frictional force of the movable caster is constructed using the Coulomb friction model. Based on the real-time equivalent rotational inertia and real-time frictional force of the movable caster, a dynamic model is constructed to calculate the angular acceleration of the movable caster. S4: Set the upper and lower thresholds for angular acceleration. When the real-time angular acceleration is less than the lower threshold, feedforward compensation is used to increase the angular acceleration of the swivel caster. When the real-time angular acceleration is greater than the upper threshold, reverse braking is used to reduce the angular acceleration of the swivel caster.

2. The dynamic motion control method for an electric swivel caster according to claim 1, characterized in that, To determine if the swivel casters are in an accelerated state, the specific steps are as follows: Using the current moment as the endpoint, a first window is constructed by tracing back the time length. Within the first window, the angular velocity of the movable caster is obtained, and a curve showing the change of angular velocity over time is plotted. The slope of the curve is calculated at each moment. When the slope of the curve is detected to be greater than 0 and continuously increasing, it is marked as the movable caster being in an acceleration state.

3. The dynamic motion control method for an electric swivel caster according to claim 1, characterized in that, The specific steps for obtaining the initial moment of inertia of the movable caster are as follows: Applying a force to the electric caster, calculate the initial moment of inertia of the caster using Newton's second law: in, This indicates the force applied to the swivel caster; Indicates the radius of the swivel caster; This represents the coefficient of kinetic friction of the ground. Apply force At that time, the angular acceleration that causes the movable caster to rotate; This represents the initial moment of inertia.

4. The dynamic motion control method for an electric swivel caster according to claim 3, characterized in that, The specific steps for calculating the real-time equivalent moment of inertia of the movable caster using the time-varying load inertia method are as follows: Based on the real-time load mass of the swivel casters, the additional equivalent inertia is calculated using the parallel axis transformation method: in, Indicates the additional equivalent inertia; Indicates load quality; Indicates the turning radius of the swivel caster; Based on the additional equivalent inertia, the time-varying load inertia method is used to add the initial rotational inertia of the swivel caster to the additional equivalent inertia: in, This represents the equivalent moment of inertia of the movable caster.

5. The dynamic motion control method for an electric swivel caster according to claim 1, characterized in that, The specific steps for constructing the real-time friction force for the accelerated rotation of the movable caster using the Coulomb friction model are as follows: Based on the dynamic friction coefficient of the ground and the real-time rotational angular velocity, the real-time frictional force of the movable caster accelerating to rotate is constructed using the Coulomb friction model: in, Indicates real-time frictional force; It represents angular velocity.

6. The dynamic motion control method for an electric swivel caster according to claim 1, characterized in that, The specific steps for constructing the angular acceleration of the movable caster rotation using a dynamic model are as follows: Based on the real-time equivalent moment of inertia and real-time friction of the swivel caster, a dynamic model is constructed to calculate the angular acceleration of the swivel caster's rotation: in, This indicates the angular acceleration of the movable caster. Indicates the damping coefficient of the rotating caster; Indicates driving torque; This represents the motor torque constant; This indicates the current of the motor.

7. The dynamic motion control method for an electric swivel caster according to claim 1, characterized in that, The upper and lower threshold values ​​for angular acceleration are set according to the following formula: in, The upper limit threshold for angular acceleration; This indicates the maximum current the motor can support for the rotation of the movable casters; This represents the lower limit threshold of angular acceleration.

8. The dynamic motion control method for an electric swivel caster according to claim 7, characterized in that, The real-time angular acceleration is compared with the upper and lower threshold values ​​to dynamically control the output current. Specifically: when At this time, feedforward compensation is used to increase the motor current, thereby increasing the angular acceleration of the swivel caster, according to the formula: in, when At that time, Reset to ; Indicates the magnitude of the current after compensation; Indicates the compensation current; Indicates the target angular acceleration; Indicates the target angular velocity; when At this time, reverse braking is used to reduce the motor current: in, Indicates the current used for reverse braking; This indicates the current after reverse braking; when At that time, Reset to ,in, This indicates the minimum current required for the motor to support the rotation of the movable casters.

9. A dynamic motion control system for an electric swivel caster, characterized in that: The control system is used to execute the control method according to any one of claims 1-8, including: The data acquisition module is used to obtain the real-time load mass of the swivel caster if the swivel caster is in an accelerated state. The inertia acquisition module is used to calculate the additional equivalent inertia based on the real-time load mass of the movable caster using the parallel axis transformation method. Based on the additional equivalent inertia, the time-varying load inertia method is used to add the initial rotational inertia of the movable caster to the additional equivalent inertia to obtain the real-time equivalent rotational inertia of the movable caster. The acceleration acquisition module is used to construct the real-time friction force of the movable caster based on the real-time rotational angular velocity of the movable caster using the Coulomb friction model. Based on the real-time equivalent rotational inertia and real-time friction force of the movable caster, a dynamic model is constructed to calculate the angular acceleration of the movable caster's rotation. The dynamic control module is used to set the upper and lower thresholds of angular acceleration. When the real-time angular acceleration is less than the lower threshold, feedforward compensation is used to increase the angular acceleration of the movable caster. When the real-time angular acceleration is greater than the upper threshold, reverse braking is used to reduce the angular acceleration of the movable caster.

10. A dynamic motion control device for an electric swivel caster, characterized in that, The device includes a storage medium and a processor, wherein the storage medium stores a computer program, which, when executed by the processor, implements the control method as described in any one of claims 1-8.

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