Hybrid brake control method for a servo hydraulic system

Abstract

The application relates to a hybrid brake control method of a servo hydraulic system, which comprises the following steps: acquiring a total brake demand of the servo hydraulic system; acquiring a real-time hydraulic oil temperature and a real-time electric quantity state of an energy storage device; executing a hierarchical decision algorithm based on the state, distributing the total brake demand into a regenerative brake torque and a hydraulic damping torque; converting the hydraulic damping torque into a compensated hydraulic control signal through a preset compensation model; and applying a first speed limit to a regenerative brake instruction converted from the regenerative brake torque, and synchronously sending the compensated hydraulic control signal. The application can balance the system thermal state and the electric quantity state, and through adaptive compensation and dynamic synchronous control, solves the problem of non-linear drift of a hydraulic valve and mismatch of multi-channel responses, and improves the precision and stability of brake control.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydraulic control, and in particular to a hybrid braking control method for a servo-hydraulic system. BACKGROUND

[0002] In the field of modern industrial manufacturing, hydraulic transmission systems play an important role in injection molding machines, die casting machines, CNC machine tools, and heavy machinery due to their high power density, high response speed, and good load stiffness. Traditional hydraulic systems usually use constant-speed motors, such as asynchronous motors, to continuously drive hydraulic pumps. In this configuration, even if the actuator is not in motion or only requires a small flow and pressure, the motor will continue to run at the rated speed, and the excess hydraulic oil can only flow back to the tank through the overflow valve, which results in a large amount of energy loss and an increase in hydraulic oil temperature.

[0003] To improve energy utilization efficiency, servo-hydraulic control technology has emerged. Servo-hydraulic systems use servo motors instead of traditional constant-speed motors. Servo motors have the ability to precisely adjust the speed and torque, which allows the system to adjust the motor's output power in real time according to the actual load demand, i.e., on-demand energy supply. When the load requires high flow, the motor runs at high speed; when the load is in the pressure maintaining or standby phase, the motor can reduce the speed or even stop. This control method significantly reduces the overflow loss in traditional systems and achieves better energy-saving effect during the running phase.

[0004] However, existing servo-hydraulic systems still face a problem in energy management: their energy-saving strategies are often limited to on-demand energy supply during the running phase, ignoring the whole-process energy optimization throughout the entire working cycle. Specifically, the energy characteristics of the system in different phases are not fully utilized. For example, during the braking phase, when the hydraulic cylinder or hydraulic motor drives a large inertia load to decelerate or stop, a large amount of kinetic energy contained in the load needs to be released. In many existing solutions, this part of energy is usually dissipated in the hydraulic oil in the form of heat through hydraulic valve throttling; or the servo motor converts the kinetic energy into electrical energy during braking, but this part of electrical energy is mostly consumed in the form of heat through the external braking resistor of the servo driver. Both of these methods result in direct waste of energy. In addition, the heat generated by the system during operation due to various energy losses is usually considered as waste heat that needs to be handled by additional energy consumption (such as starting a cooling fan or water cooling system), rather than as a recyclable resource. SUMMARY

[0005] To enable on-demand energy supply during operation, effectively recover and reuse the kinetic energy during braking and the thermal energy generated during operation, and achieve comprehensive energy efficiency improvement of the servo-hydraulic system throughout the entire working cycle, the present application provides a hybrid braking control method for a servo-hydraulic system.

[0006] The application provides a hybrid braking control method of a servo hydraulic system, which adopts the following technical scheme:

[0007] A hybrid braking control method of a servo hydraulic system, comprising the following steps:

[0008] S1. Obtaining the total braking demand of the servo hydraulic system; wherein the total braking demand is the target braking torque determined by a motion controller for realizing a target deceleration process;

[0009] S2. Obtaining the real-time hydraulic oil temperature of the servo hydraulic system and the real-time power state of the energy storage device; based on the real-time hydraulic oil temperature and the real-time power state, a hierarchical decision algorithm is executed to distribute the total braking demand into a regenerative braking torque and a hydraulic damping torque;

[0010] S3. Converting the regenerative braking torque into a regenerative braking instruction;

[0011] S4. Based on the hydraulic damping torque, the real-time hydraulic oil temperature and the real-time system pressure, a preset compensation model is queried to determine a compensated hydraulic control signal;

[0012] S5. Sending the regenerative braking instruction to a servo driver and imposing a first rate limit on the regenerative braking instruction, which matches the dynamic response of the servo hydraulic system;

[0013] S6. Sending the compensated hydraulic control signal to a hydraulic control valve to realize dynamic synchronous control of the regenerative braking channel and the hydraulic damping channel.

[0014] By adopting the above technical scheme, the target braking torque determined by the motion controller for realizing the target deceleration process is first obtained. The target braking torque serves as the input of all subsequent energy distribution. Then, the system obtains the real-time hydraulic oil temperature and the real-time power state of the energy storage device. A hierarchical decision algorithm takes these two states as the basis for judgment, and dynamically distributes the target braking torque obtained in the previous step into a regenerative braking torque and a hydraulic damping torque. The algorithm realizes the protection of the system thermal safety and the energy storage safety by preferentially distributing to the regenerative channel when the hydraulic oil temperature is too high, or preferentially distributing to the hydraulic damping channel when the energy storage power is saturated. Then, the regenerative braking torque is converted into a regenerative braking instruction executable by the servo driver, which is used for subsequent servo motor control.

[0015] Meanwhile, the system determines the compensated hydraulic control signal by querying a preset compensation model based on the hydraulic damping torque, real-time hydraulic oil temperature and real-time system pressure. This step compensates the non-linear characteristics and parameter drift of the hydraulic control valve due to oil temperature changes and pressure fluctuations by using the compensation model. The principle is to calculate an accurate control signal that has been pre-compensated according to the real-time working conditions, i.e. oil temperature and pressure. This signal ensures that the actual torque generated by the hydraulic damping channel can accurately track the hydraulic damping torque allocated by the hierarchical decision algorithm, which improves the fidelity of the control and reduces the control internal consumption.

[0016] Finally, the system performs dynamic synchronization of the two brake channels. The system sends the regenerative braking instruction to the servo driver and applies a first rate limit to the instruction that matches the dynamic response of the servo hydraulic system. At the same time, the system sends the compensated hydraulic control signal to the hydraulic control valve. The electrical response speed of the servo driver is much faster than the physical response speed of the hydraulic control valve. By applying the first rate limit, the system artificially slows down the effective rate of the fast regenerative brake channel, so that it is consistent with the effective rate of the slow hydraulic damping channel. This synchronous control ensures smooth superposition of the torque of the two brake channels, avoiding braking impact and system oscillation caused by response mismatch, which has direct benefits for protecting mechanical structures and improving braking smoothness.

[0017] Optionally, S1 includes the following sub-steps:

[0018] S11. Monitor the current motion state of the servo hydraulic system, wherein the current motion state includes the current speed;

[0019] S12. Obtain the target motion curve corresponding to the target deceleration process, wherein the target motion curve defines the target speed and the deceleration time;

[0020] S13. Obtain the total inertia of the system driven by the servo hydraulic system;

[0021] S14. Calculate and determine the target braking torque according to the current motion state, the target motion curve and the total inertia of the system.

[0022] By adopting the technical scheme, the method monitors a current motion state of the servo hydraulic system to obtain the current speed, which is used as an initial condition for calculation. Meanwhile, the system obtains a target motion curve corresponding to the target deceleration process, which defines a target speed and a deceleration time, and provides an end condition and a process constraint for calculation. The system also obtains a total inertia of a system driven by the servo hydraulic system, which is a physical parameter required for performing braking. Finally, the system calculates and determines the target braking torque according to the current motion state, the target motion curve and the total inertia of the system. The calculation process ensures that the target braking torque is a required torque precisely matching the physical characteristics of the system, rather than a preset value, which improves the accuracy of subsequent braking distribution.

[0023] Optionally, the S2 comprises the following sub-steps:

[0024] S21. presetting a critical temperature threshold, a warning temperature threshold, a first electric quantity threshold group and a second electric quantity threshold group;

[0025] S22. comparing the real-time hydraulic oil temperature with the critical temperature threshold and comparing the real-time hydraulic oil temperature with the warning temperature threshold;

[0026] when the real-time hydraulic oil temperature is greater than or equal to the critical temperature threshold, determining a regeneration factor as 1;

[0027] when the real-time hydraulic oil temperature is less than the critical temperature threshold and greater than or equal to the warning temperature threshold, calculating the regeneration factor based on the real-time electric quantity state and the first electric quantity threshold group;

[0028] when the real-time hydraulic oil temperature is less than the warning temperature threshold, calculating the regeneration factor based on the real-time electric quantity state and the second electric quantity threshold group; wherein a regeneration braking intervention electric quantity interval defined by the first electric quantity threshold group is higher than a regeneration braking intervention electric quantity interval defined by the second electric quantity threshold group;

[0029] S23. calculating the regeneration braking torque and the hydraulic damping torque according to the determined regeneration factor and the total braking demand.

[0030] By adopting the technical scheme, the critical temperature threshold, the warning temperature threshold, the first electric quantity threshold group and the second electric quantity threshold group are preset. The system compares the real-time hydraulic oil temperature with the critical temperature threshold and the warning temperature threshold.

[0031] when the real-time hydraulic oil temperature is greater than or equal to the critical temperature threshold, the system determines a regeneration factor as 1. This setting forces all braking energy to enter the regeneration channel and stops the hydraulic damping channel from running, thereby avoiding the generation of additional heat by the hydraulic system at high temperatures.

[0032] When the real-time hydraulic oil temperature is less than the critical temperature threshold and greater than or equal to the early warning temperature threshold, the system calculates the regenerative factor based on the real-time state of charge and the first set of state of charge thresholds. When the real-time hydraulic oil temperature is less than the early warning temperature threshold, the system calculates the regenerative factor based on the real-time state of charge and the second set of state of charge thresholds.

[0033] The regenerative braking intervention state of charge interval defined by the first set of state of charge thresholds is higher than the regenerative braking intervention state of charge interval defined by the second set of state of charge thresholds. This design allows the system to increase the tolerance of the state of charge of the energy storage device when the hydraulic oil temperature is high, and reduces the intervention of the hydraulic damping, thereby prioritizing the management of system heat.

[0034] Finally, the system calculates the regenerative braking torque and the hydraulic damping torque according to the determined regenerative factor and the total braking demand.

[0035] Optionally, the S3 comprises the following sub-steps:

[0036] S31. Obtain the maximum regenerative torque limit of the servo motor corresponding to the servo drive;

[0037] S32. Compare the regenerative braking torque with the maximum regenerative torque limit;

[0038] S33. Determine the smaller value of the regenerative braking torque and the maximum regenerative torque limit as a target regenerative torque;

[0039] S34. Convert the target regenerative torque into the regenerative braking instruction.

[0040] By adopting the above technical solution, the method obtains the maximum regenerative torque limit of the servo motor corresponding to the servo drive. The system compares the regenerative braking torque with the maximum regenerative torque limit, and determines the smaller value of the two as a target regenerative torque. This step ensures that the finally determined target regenerative torque will not exceed the physical bearing capacity of the servo motor or the servo drive, avoiding hardware failure or protective shutdown caused by instruction overload. Finally, the system converts the target regenerative torque into the regenerative braking instruction.

[0041] Optionally, the preset compensation model is a reference model; the reference model defines the target dynamic response corresponding to the hydraulic damping torque;

[0042] The S4 comprises the following sub-steps:

[0043] S41. Real-time acquiring an actual dynamic response of the hydraulic damping torque generated under the driving of the hydraulic control valve;

[0044] S42. Real-time calculating an identification error between the actual dynamic response and the target dynamic response;

[0045] S43. Real-time adjusting a control gain parameter based on the identification error through a preset adaptive law;

[0046] S44. Determining the compensated hydraulic control signal based on the hydraulic damping torque and the control gain parameter.

[0047] By adopting the above technical solution, the preset compensation model is defined as a reference model, which defines the target dynamic response corresponding to the hydraulic damping torque.

[0048] The method real-time acquires an actual dynamic response of the hydraulic damping torque generated under the driving of the hydraulic control valve. The system real-time calculates an identification error between the actual dynamic response and the target dynamic response. Based on the identification error, a preset adaptive law real-time adjusts a control gain parameter. Finally, the system determines the compensated hydraulic control signal based on the hydraulic damping torque and the real-time adjusted control gain parameter.

[0049] This online adjustment process enables the system to continuously minimize the identification error, forcing the actual dynamic response to track the target dynamic response. This adaptive compensation compensates for parameter drift caused by component wear, oil viscosity changes, or other working condition changes, improving the fidelity of the control system and reducing control overhead.

[0050] Optionally, the S5 includes the following sub-steps:

[0051] S51. Pre-calibrating or real-time identifying the dynamic response characteristic of the hydraulic control valve to determine a hydraulic response time;

[0052] S52. Setting the hydraulic response time as a target synchronous ramp time;

[0053] S53. Configuring the first rate limit as a ramp generator, a ramp-up time of the ramp generator being equal to the target synchronous ramp time;

[0054] S54. Sending the regenerative braking instruction to the servo driver after processing by the ramp generator.

[0055] By adopting the technical scheme, the dynamic response characteristic of the hydraulic control valve is calibrated in advance or identified in real time to determine a hydraulic response time. The hydraulic response time is set as a target synchronization ramp time. The first rate limit is configured as a ramp generator with a ramp rising time equal to the target synchronization ramp time. The regenerative braking command is processed by the ramp generator before being sent to the servo driver. The processing process converts a transient regenerative braking command into a command with a smooth rise over time, and the rise rate is artificially limited to match the hydraulic response time. The design forces the response rate of the fast electrical braking channel to match the response rate of the slow hydraulic braking channel, ensuring smooth superposition of the torque of the two braking channels and avoiding braking impact and system oscillation caused by response mismatch.

[0056] Optionally, the S6 comprises the following sub-steps:

[0057] S61. The compensated hydraulic control signal is sent to a proportional relief valve or a proportional throttle valve to start the hydraulic damping channel; wherein the hydraulic control valve is a proportional relief valve or a proportional throttle valve;

[0058] S62. The sending time of the compensated hydraulic control signal is synchronized with the starting time of the first rate limit;

[0059] S63. The proportional relief valve or the proportional throttle valve generates throttling loss of hydraulic oil according to the compensated hydraulic control signal to realize the hydraulic damping torque.

[0060] By adopting the technical scheme, the compensated hydraulic control signal is sent to a proportional relief valve or a proportional throttle valve to start the hydraulic damping channel. The sending time of the compensated hydraulic control signal is synchronized with the starting time of the first rate limit. The synchronous execution mechanism eliminates the timing deviation caused by task scheduling or bus delay inside the controller, ensuring that the regenerative braking channel and the hydraulic damping channel start at the same time. The proportional relief valve or the proportional throttle valve generates throttling loss of hydraulic oil according to the received compensated hydraulic control signal, and the physical process realizes the hydraulic damping torque.

[0061] Optionally, the S44 comprises the following sub-steps:

[0062] S441. An intermediate hydraulic control signal is determined based on the hydraulic damping torque and the real-time adjusted control gain parameter;

[0063] S442. The valve dead zone parameter and the hysteresis loop parameter of the hydraulic control valve are obtained in advance;

[0064] S443. applying a valve dead zone compensation to the intermediate hydraulic control signal, the valve dead zone compensation being configured to ensure that the hydraulic control valve starts to act when the intermediate hydraulic control signal is greater than the valve dead zone parameter;

[0065] S444. applying a hysteresis compensation to the signal after the valve dead zone compensation according to the change direction of the intermediate hydraulic control signal, the hysteresis compensation being configured to offset the influence of the hysteresis loop parameter;

[0066] S445. determining the signal after the hysteresis compensation as the compensated hydraulic control signal.

[0067] By adopting the technical scheme, the method determines an intermediate hydraulic control signal based on the hydraulic damping torque and the real-time adjusted control gain parameter. The system pre-acquires the valve dead zone parameter and the hysteresis loop parameter of the hydraulic control valve. The system applies a valve dead zone compensation to the intermediate hydraulic control signal to ensure that the hydraulic control valve starts to act when the signal is greater than the valve dead zone parameter, and applies a hysteresis compensation to the signal after the valve dead zone compensation according to the change direction of the intermediate hydraulic control signal to offset the influence of the hysteresis loop parameter. The system determines the signal after the hysteresis compensation as the compensated hydraulic control signal. The two-stage compensation matches the output signal of the adaptive control with the physical nonlinear characteristics of the hydraulic valve, and improves the execution accuracy of the signal finally sent to the hydraulic control valve.

[0068] Optionally, the S51 includes the following sub-steps:

[0069] S511. performing the pre-calibration in a device offline debugging stage; wherein the calibration process includes: measuring the actual dynamic response time of the hydraulic control valve at a plurality of preset hydraulic oil temperature points and a plurality of preset system pressure points;

[0070] S512. establishing a multi-dimensional response time lookup table according to the calibration data obtained by the pre-calibration, wherein the response time lookup table stores the mapping relationship between the hydraulic oil temperature, the system pressure and the hydraulic response time;

[0071] S513. acquiring the real-time hydraulic oil temperature and the real-time system pressure when the system enters a real-time running stage;

[0072] S514. determining the hydraulic response time under the current working condition by querying the response time lookup table and combining the real-time hydraulic oil temperature and the real-time system pressure.

[0073] Optionally, the S52 includes the following sub-steps:

[0074] S521. receiving the hydraulic response time value;

[0075] S522. setting the target synchronization ramp time parameter as the received hydraulic response time value in the control register of the current braking cycle.

[0076] Optionally, the S53 comprises the following sub-steps:

[0077] S531. accessing the ramp generator function block in the servo drive or motion controller;

[0078] S532. dynamically updating the configuration parameter of the ramp up time of the ramp generator function block as the target synchronization ramp time.

[0079] Optionally, the S54 comprises the following sub-steps:

[0080] S541. obtaining the regenerative braking instruction;

[0081] S542. taking the regenerative braking instruction as the target input value of the ramp generator;

[0082] S543. the ramp generator generating an intermediate instruction sequence that smoothly rises over time according to the ramp up time of the ramp generator;

[0083] S544. sending the intermediate instruction sequence as the final running instruction to the servo drive.

[0084] Optionally, the S61 comprises the following sub-steps:

[0085] S611. determining the hardware interface type of the hydraulic control valve, the hardware interface type comprising an analog current interface, an analog voltage interface or a field bus interface;

[0086] S612. performing signal conversion on the compensated hydraulic control signal according to the hardware interface type;

[0087] S613. if the hardware interface type is an analog interface, the signal conversion comprises: converting the compensated hydraulic control signal into a corresponding digital analog converter original value, and outputting through a digital analog conversion channel;

[0088] S614. if the hardware interface type is a field bus interface, the signal conversion comprises: packaging the compensated hydraulic control signal into a data packet conforming to the field bus protocol, and sending through the field bus interface.

[0089] Optionally, the S62 comprises the following sub-steps:

[0090] S621. Establish a high-precision, hardware-based distributed clock for synchronizing the servo drive and the I / O module of the hydraulic control valve;

[0091] S622. Configure a clock synchronization task in the controller, the execution period of which is triggered by the distributed clock;

[0092] S623. Configure the start logic of the first rate limit and the sending logic of the compensated hydraulic control signal in the clock synchronization task;

[0093] S624. Start the first rate limit and send the compensated hydraulic control signal simultaneously in the same execution period of the clock synchronization task to eliminate task jitter and ensure that the sending time is synchronized with the starting time.

[0094] In summary, the present application includes at least one of the following beneficial technical effects:

[0095] 1. The method dynamically allocates regenerative braking torque and hydraulic damping torque based on real-time hydraulic oil temperature and real-time power state through a hierarchical decision algorithm. This design enforces regenerative braking when the system faces overheating risks and switches to hydraulic damping when the energy storage device approaches saturation, achieving coordinated management of system thermal safety and energy storage safety.

[0096] 2. The method uses adaptive control to compensate for the nonlinearity of the hydraulic damping channel. The system calculates the identification error between the actual dynamic response and the target dynamic response of the reference model in real time, and adjusts the control gain parameter in real time using a pre-set adaptive law. This process enables the control system to dynamically compensate for parameter drift caused by component wear or changes in working conditions, improving control fidelity and reducing energy consumption.

[0097] 3. The method realizes dynamic synchronization of the regenerative braking channel and the hydraulic damping channel. The system configures a ramp generator to limit the effective rate of the regenerative braking command to match the hydraulic response time, and uses a clock synchronization task to ensure that the commands of the two channels are started in the same execution period. This synchronous control solves the speed mismatch problem between the electrical response and the hydraulic response, ensures smooth superposition of torque, and avoids braking impact and system oscillation. BRIEF DESCRIPTION OF DRAWINGS

[0098] Figure 1 A program block diagram of a hybrid braking control method for a servo hydraulic system in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0099] The present application will be further described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are intended to be illustrative only and not limiting of the application.

[0100] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the inventive concept. As part of the description, some of the diagrams in the present disclosure are presented in block diagram form to avoid obscuring the disclosed principles. Some features of actual implementations can not be described in detail to avoid obscuring the inventive subject matter. Also, the language used in the present disclosure has been principally selected for readability and instructional purposes and can not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in the specification to "one implementation" or "an implementation" means that a particular feature, structure, or characteristic described is included in at least one implementation, and multiple references to "one implementation" or "an implementation" do not necessarily all refer to the same implementation.

[0101] The terms "a," "an," and "the" are not intended to refer to singular entities, but include the general class of which a specific example can be used for illustration. The use of the terms "a" or "an" can mean any number of including "one," "one or more," "at least one," and "one or more than one." The term "or" means any one of the alternatives, as well as any combination of the alternatives, including all of the alternatives, unless the alternatives are expressly indicated to be mutually exclusive. The phrase "at least one of" followed by a list of items means individual items in the list or any combination of items in the list, unless expressly indicated to the contrary. The phrase "at least one of" followed by a list of items means individual items in the list or any combination of items in the list, unless expressly indicated to the contrary.

[0102] Referring to Figure 1 The embodiments of the present application disclose a hybrid brake control method of a servo hydraulic system, comprising the following steps S1-S6.

[0103] S1. obtaining a total brake demand of the servo hydraulic system; wherein the total brake demand is a target brake torque determined by a motion controller for realizing a target deceleration process.

[0104] The servo hydraulic system is usually composed of a servo motor, a hydraulic pump, a hydraulic actuator such as a hydraulic cylinder or a hydraulic motor, and corresponding control valves and sensors. The system combines the precise speed regulation characteristics of the servo motor with the high power density characteristics of the hydraulic transmission, and is applied to industrial equipment that requires high precision control and high dynamic response, such as injection molding machines, die casting machines or metal forming presses.

[0105] In the working condition of the present application, when a large template of an injection molding machine performs an action such as mold opening and closing and needs to be quickly decelerated or stopped, a large inertia load driven by a servo hydraulic system will generate braking energy. In the prior art, the braking energy is usually dissipated in the form of heat through the braking resistor of a servo driver, or dissipated in the hydraulic oil through the throttling loss of a hydraulic valve, which causes energy waste and increases the thermal load of the system.

[0106] The total braking demand, i.e. the target braking torque, is the total resisting torque required to be applied by the upper motion controller to make the large inertia load, such as the template of an injection molding machine, stop according to a preset target deceleration process. The size of the demand is mainly affected by the system total inertia of the load and the target deceleration acceleration required. The total braking demand can be obtained by real-time calculation by the motion controller according to the target deceleration process such as the target speed curve and time, and the physical parameters of the system such as the system total inertia, or can be the braking torque value of a specific work step found from a preset process parameter table.

[0107] Specifically, in an embodiment, S1 includes the following sub-steps S11-S14.

[0108] S11. Monitor the current motion state of the servo hydraulic system, wherein the current motion state includes the current speed.

[0109] S12. Obtain the target motion curve corresponding to the target deceleration process, wherein the target motion curve defines the target speed and the deceleration time.

[0110] S13. Obtain the system total inertia driven by the servo hydraulic system.

[0111] S14. Calculate and determine the target braking torque according to the current motion state, the target motion curve, and the system total inertia.

[0112] The current motion state includes the real-time operating parameters of the load driven by the servo hydraulic system, and specifically can include the current position, the current acceleration, and the current speed. The current speed is the instantaneous linear speed or angular speed of the load at the moment when the braking control is initiated. The target deceleration process is a controlled deceleration of the load performed by the actuator of the servo hydraulic system, such as a hydraulic cylinder or a hydraulic motor. The target speed and the deceleration time are process parameters defined for the load.

[0113] Continuing with the example of an injection molding machine, if the current speed of the template as the load is 0.5 m / s, the target motion curve can define the target speed as 0 m / s and the deceleration time as 100 ms. The system total inertia is determined by the masses of all moving parts of the template, the hydraulic cylinder piston, the piston rod, and the hydraulic oil flowing in the pipeline. The system total inertia is a physical parameter that determines the size of the kinetic energy of the system and directly affects the size of the braking force required to achieve the target deceleration process.

[0114] The calculation process of the target braking torque is as follows: first, according to the current motion state and the target motion curve, the required target deceleration a is determined. The calculation formula is . Wherein is the current speed, is the target speed, is the deceleration time. In the above example, . Then, according to the obtained total system inertia m and the determined target deceleration a, the target braking torque corresponding to the target braking torque is calculated . The calculation formula is . If the total system inertia m is 500 kg, the required target braking force is . The target braking force is the specific embodiment of the target braking torque in the motion controller.

[0115] S2. Obtain the real-time hydraulic oil temperature of the servo hydraulic system and the real-time power state of the energy storage device; based on the real-time hydraulic oil temperature and the real-time power state, execute a hierarchical decision algorithm to distribute the total braking demand into regenerative braking torque and hydraulic damping torque.

[0116] The real-time hydraulic oil temperature and the real-time power state of the energy storage device are two core inputs of the hierarchical decision algorithm. The real-time hydraulic oil temperature reflects the thermal load state of the hydraulic system. If the temperature is too high, the system will continue to generate heat through the hydraulic damping, which will lead to system thermal runaway or damage to the sealing element. The real-time power state, such as the state of charge percentage, reflects the remaining capacity of the energy storage device. If the state is too high, the energy storage device will not be able to continue to receive regenerative power.

[0117] The hierarchical decision algorithm is to arbitrate between two mutually restrictive braking channels. Regenerative braking torque and hydraulic damping torque are two different energy dissipation methods. Regenerative braking torque is the braking torque generated by the servo motor in the power generation mode, which converts the load kinetic energy into electrical energy and stores it in the energy storage device. Hydraulic damping torque is the braking torque generated by the hydraulic control valve through throttling loss, which converts the load kinetic energy into heat energy and dissipates it in the hydraulic oil. The hierarchical decision algorithm determines the proportion of regenerative braking torque and hydraulic damping torque according to the real-time hydraulic oil temperature and the real-time power state, so as to cooperatively manage the system thermal load and power load.

[0118] Specifically, in some embodiments, S2 includes the following sub-steps S21-S23.

[0119] S21. Pre-set critical temperature threshold, warning temperature threshold, first power threshold group and second power threshold group.

[0120] S22. Compare the real-time hydraulic oil temperature with a critical temperature threshold value, and compare the real-time hydraulic oil temperature with a pre-warning temperature threshold value.

[0121] When the real-time hydraulic oil temperature is greater than or equal to the critical temperature threshold value, determine a regeneration factor as 1.

[0122] When the real-time hydraulic oil temperature is less than the critical temperature threshold value and greater than or equal to the pre-warning temperature threshold value, calculate the regeneration factor based on the real-time state of charge and a first set of state of charge threshold values.

[0123] When the real-time hydraulic oil temperature is less than the pre-warning temperature threshold value, calculate the regeneration factor based on the real-time state of charge and a second set of state of charge threshold values; wherein the regeneration braking intervention state of charge interval defined by the first set of state of charge threshold values is higher than the regeneration braking intervention state of charge interval defined by the second set of state of charge threshold values.

[0124] S23. Calculate a regeneration braking torque and a hydraulic damping torque according to the determined regeneration factor and a total braking demand.

[0125] The critical temperature threshold value is an upper limit temperature for protecting the hydraulic system hardware, for example 85 degrees Celsius, above which the hydraulic seals can be damaged. The pre-warning temperature threshold value is a lower temperature point, for example 70 degrees Celsius, at which the system starts to preferentially manage thermal load. The first set of state of charge threshold values and the second set of state of charge threshold values are parameter sets for determining the real-time state of charge at different thermal states. The first set of state of charge threshold values is applied in a high temperature state, i.e. in a pre-warning interval, and defines a higher intervention interval than the second set of state of charge threshold values. This setting makes the system more tolerant of a higher real-time state of charge at high temperatures, and preferentially selects regeneration braking over heat-generating hydraulic damping. The second set of state of charge threshold values is applied in a normal temperature state, and defines a lower intervention interval for earlier activation of hydraulic damping to protect the energy storage device from overcharging.

[0126] The system compares the real-time hydraulic oil temperature with threshold values. In the above example, if the real-time hydraulic oil temperature is 90 degrees Celsius, it is greater than or equal to the critical temperature threshold value of 85 degrees Celsius, at which point the system is in a thermal runaway risk state. The system forcibly determines the regeneration factor as 1. If the real-time hydraulic oil temperature is 75 degrees Celsius, it is less than the critical temperature threshold value of 85 degrees Celsius but greater than or equal to the pre-warning temperature threshold value of 70 degrees Celsius, at which point the system is in a thermal load pre-warning state. The system calculates the regeneration factor based on the real-time state of charge and the first set of state of charge threshold values. The first set of state of charge threshold values can be defined to start intervention of hydraulic damping only when the real-time state of charge exceeds 95%. If the real-time hydraulic oil temperature is 60 degrees Celsius, it is less than the pre-warning temperature threshold value of 70 degrees Celsius, at which point the system is in a normal working state. The system calculates the regeneration factor based on the real-time state of charge and the second set of state of charge threshold values. The second set of state of charge threshold values can be defined to start intervention of hydraulic damping when the real-time state of charge exceeds 85%.

[0127] The system calculates the regenerative braking torque and the hydraulic damping torque according to the determined regenerative factor and the total braking demand. The regenerative factor k is a coefficient between 0 and 1. The calculation formula of the regenerative braking torque is wherein is the total braking demand, i.e. the target braking torque. The calculation formula of the hydraulic damping torque is .

[0128] Continuing the above example, the total braking demand, i.e. the target braking torque, is -2500 Newton. If the temperature threshold is above the critical temperature threshold, the regenerative factor k = 1. The calculation results in , If the system is in normal working state, and the second set of electric quantity thresholds is defined as linear interpolation between 85% and 95%, when the real-time electric quantity state is 90%, the calculation results in the regenerative factor k = 0.5. The calculation results in , .

[0129] S3. Convert the regenerative braking torque into a regenerative braking instruction.

[0130] The regenerative braking instruction is an electronic control signal sent by the motion controller to the servo driver. The signal is a specific instruction format that the servo driver can recognize and execute, such as a torque set value, a current loop instruction, or a data packet sent through a field bus.

[0131] The regenerative braking torque is a physical target value or a logical value calculated in S2, such as -1250 Newton. The value represents the braking force size that the system decision layer expects the servo motor to provide. The conversion process translates the physical target value of the system decision layer into an electronic instruction format that the hardware execution layer, i.e. the servo driver, can understand, so that the driver can accurately control the electromagnetic torque of the servo motor, making it work in the power generation state to output the desired regenerative braking torque.

[0132] Specifically, in some embodiments, S3 includes the following sub-steps S31-S34.

[0133] S31. Obtain the maximum regenerative torque limit of the servo motor corresponding to the servo driver.

[0134] S32. Compare the regenerative braking torque with the maximum regenerative torque limit.

[0135] S33. Determine the smaller value between the regenerative braking torque and the maximum regenerative torque limit as a target regenerative torque.

[0136] S34. Convert the target regenerative torque into a regenerative braking instruction.

[0137] The maximum regenerative torque limit is an inherent hardware protection parameter of the servo drive or servo motor. This parameter defines the maximum torque that the servo motor can safely withstand when operating in the braking mode, and its role is to prevent excessive regenerative current or power from damaging the power module of the servo drive or the winding of the servo motor.

[0138] S32 and S33 constitute an amplitude limiting logic. The regenerative braking torque calculated by S2 is an expected value based on the energy management requirements of the system (such as thermal management and power management), which may exceed the physical bearing capacity of the hardware. By comparing this expected value with the maximum regenerative torque limit and taking the smaller value of the two as the target regenerative torque, it can be ensured that the torque instruction ultimately executed by the servo drive is always within its safe working range, avoiding damage to the hardware due to overload.

[0139] The process of converting the target regenerative torque into a regenerative braking instruction in S34 is to convert the physical torque value determined by S33 (for example, -1200 Nm) into an electronic instruction that the servo drive can execute. If the servo drive is working in torque control mode, the target regenerative torque will be formatted into a digital message, such as a data frame of CANopen or EtherCAT protocol, or calibrated as an analog signal, such as a voltage value of -10V to +10V. After the servo drive receives the regenerative braking instruction, its internal torque loop will control the motor to output the target regenerative torque.

[0140] S4. Based on the hydraulic damping torque, the real-time hydraulic oil temperature and the real-time system pressure, the compensation model is queried to determine the compensated hydraulic control signal.

[0141] S4 is used to accurately convert the physical target value of the hydraulic damping torque into an electronic control signal that can be sent to the hydraulic control valve. The physical characteristics of the hydraulic control valve, i.e. the relationship between the input electrical signal and the output damping torque, have nonlinear and parameter drift characteristics. This characteristic is affected by the viscosity of the oil affected by the real-time hydraulic oil temperature, and the hydrodynamic force affected by the real-time system pressure.

[0142] The preset compensation model is a mathematical or data model that stores the characteristics of the hydraulic control valve. Its role is to receive the hydraulic damping torque, the real-time hydraulic oil temperature and the real-time system pressure as input, and output a compensated hydraulic control signal that can accurately achieve the hydraulic damping torque.

[0143] The preset compensation model can have various embodiments. In one embodiment, the preset compensation model can be a static three-dimensional lookup table. The lookup table is generated in the offline calibration stage and stores the control signal values required to achieve different torques under different temperature and pressure combinations. In another embodiment, the preset compensation model can be a dynamic adaptive model, such as S41 to S44, which adjusts its control parameters in real time through online identification to compensate for parameter drifts such as system aging or wear that are not reflected in calibration.

[0144] Specifically, in some embodiments, the preset compensation model is a reference model; the reference model defines the target dynamic response corresponding to the hydraulic damping torque. S4 includes the following sub-steps S41-S44.

[0145] S41. Real-time acquisition of the actual dynamic response of the hydraulic damping torque generated under the drive of the hydraulic control valve.

[0146] S42. Real-time calculation of the identification error between the actual dynamic response and the target dynamic response.

[0147] S43. Based on the identification error, the control gain parameter is adjusted in real time through the preset adaptive law.

[0148] S44. Based on the hydraulic damping torque and the control gain parameter, the compensated hydraulic control signal is determined.

[0149] The preset compensation model is defined as a reference model in this embodiment. The reference model is a pre-defined mathematical model, which is usually a ideal second-order system, used to define the target dynamic response corresponding to the hydraulic damping torque. The input of the model is the hydraulic damping torque, and the output is the target dynamic response. The target dynamic response represents the time trajectory required by the hydraulic damping channel to establish the required torque in the ideal state (e.g. no oscillation, no overshoot).

[0150] S4 real-time acquisition of the actual dynamic response of the hydraulic damping torque generated under the drive of the hydraulic control valve, such as the actual pressure rise curve monitored by the pressure sensor. The system calculates the identification error between the actual dynamic response and the target dynamic response in real time. The identification error is calculated to quantify the deviation between the actual performance of the physical system (hydraulic valve, oil) and the ideal performance. The deviation can be caused by oil temperature change, load fluctuation or valve wear. The identification error as a key feedback signal drives the subsequent adaptive adjustment.

[0151] Based on the identification error, a pre-defined adaptive law adjusts the control gain parameters in real-time. The pre-defined adaptive law is an algorithm, such as MIT rule based on gradient descent method or Lyapunov stability theory, which calculates the adjustment amount of the control gain parameters according to the size and trend of the identification error. The control gain parameters are coefficients inside the hydraulic damping channel control loop (e.g. PID controller), such as proportional gain, integral gain and derivative gain. The pre-defined adaptive law modifies these gain values in real-time, for example, when the identification error shows that the actual response is slower than the target response, the adaptive law increases the proportional gain.

[0152] Finally, the system calculates and determines the compensated hydraulic control signal based on the hydraulic damping torque (as the control target) and the real-time adjusted control gain parameters. This process ensures that the signal sent to the hydraulic control valve is dynamically optimized, which can force the actual dynamic response to track the target dynamic response, thereby achieving online compensation for system nonlinearities and parameter drift.

[0153] Further, S44 includes the following sub-steps S441-S445.

[0154] S441. Based on the hydraulic damping torque and the real-time adjusted control gain parameters, determine an intermediate hydraulic control signal.

[0155] S442. Pre-obtain the valve dead zone parameter and hysteresis loop parameter of the hydraulic control valve.

[0156] S443. Apply a valve dead zone compensation to the intermediate hydraulic control signal, which is used to ensure that the hydraulic control valve only starts to act when the intermediate hydraulic control signal is greater than the valve dead zone parameter.

[0157] S444. According to the change direction of the intermediate hydraulic control signal, apply a hysteresis compensation to the signal after the valve dead zone compensation, which is used to offset the influence of the hysteresis loop parameter.

[0158] S445. Determine the signal after the hysteresis compensation as the compensated hydraulic control signal.

[0159] The intermediate hydraulic control signal is the original control output value calculated by the adaptive control loop (e.g. PID controller) according to the hydraulic damping torque and the real-time adjusted control gain parameters. For example, the adaptive PID controller calculates that a signal corresponding to 5.0V is needed. This signal is the ideal electronic signal to achieve the target dynamic response, but it has not yet considered the physical nonlinearities of the hydraulic control valve. Determining this intermediate hydraulic control signal is the basis for subsequent physical characteristic compensation.

[0160] Valve dead zone and hysteresis parameters are inherent physical nonlinearities of a hydraulic control valve. Valve dead zone parameter defines the minimum input signal value required to initiate movement of the spool of the hydraulic control valve. Hysteresis parameter defines the actual position deviation of the spool at the same input signal value when the input signal changes in different directions (increasing or decreasing). These two parameters are acquired to modify the intermediate hydraulic control signal.

[0161] S443 applies valve dead zone compensation to the intermediate hydraulic control signal. For example, if the valve dead zone parameter is 0.5V and S441 determines the intermediate hydraulic control signal to be 3.0V, S443's compensation algorithm modifies the signal to 3.5V. This compensation ensures that the signal sent to the valve is able to overcome the dead zone and cause the valve to actually move.

[0162] The direction of change of the intermediate hydraulic control signal refers to whether the signal is increasing or decreasing in consecutive control cycles. The direction of change is determined by the controller comparing the current cycle value to the previous cycle value. Hysteresis compensation is an algorithm that modifies the signal based on the direction of change, S444 applies hysteresis compensation to the signal after valve dead zone compensation.

[0163] Continuing the example, the signal is 3.5V and the hysteresis parameter corresponds to a compensation value of 0.1V. If the direction of change of the intermediate hydraulic control signal is increasing (e.g. from 2.9V to 3.0V), S444's compensation algorithm further modifies the signal to 3.5V + 0.1V = 3.6V. If the direction of change of the intermediate hydraulic control signal is decreasing (e.g. from 3.1V to 3.0V), S444's compensation algorithm modifies it to 3.5V - 0.1V = 3.4V. This modification ensures that the spool reaches a position closer to the target, regardless of the direction of change of the signal.

[0164] S445 determines the signal after hysteresis compensation (e.g. 3.6V or 3.4V) as the final compensated hydraulic control signal. This signal is then sent to the hydraulic control valve in S6.

[0165] S5. Send the regenerative braking command to the servo driver and apply a first rate limit to the regenerative braking command that matches the dynamic response of the servo hydraulic system.

[0166] The first rate limit is a digital function that controls the rate of change of the regenerative braking command, such as a ramp generator. It converts an instantaneously changing torque command into a ramp command that rises or falls smoothly over a specific time period. The rate limit acts as a dynamic synchronization mechanism, with its rate value determined by the dynamic response of the servo hydraulic system, specifically the physical response time of the hydraulic control valve in S6.

[0167] The limit is imposed on the regenerative braking command to solve the dynamic response mismatch between the regenerative braking channel (electrical channel) in step S5 and the hydraulic damping channel (physical channel) in step S6. The electrical response speed of the servo driver is usually in the order of milliseconds, much faster than the physical response speed of the hydraulic control valve, which can take tens to hundreds of milliseconds. Without the limit, the braking torque of S5 will be applied instantaneously, while the braking torque of S6 will be applied with a delay, resulting in a shock in the total braking force and system oscillation. The first rate limit forces the response rate of the regenerative braking channel to be artificially slowed down to match the response rate of the hydraulic damping channel, thereby ensuring smooth superposition of the torque of the two channels and achieving dynamic synchronous control.

[0168] Specifically, in some embodiments, S5 includes the following sub-steps S51-S54.

[0169] S51. Pre-calibrate or identify in real time the dynamic response characteristics of the hydraulic control valve to determine a hydraulic response time.

[0170] Determining the hydraulic response time is the basis for achieving dynamic synchronous control. This time parameter quantifies the physical response delay of the hydraulic damping channel and is used to set the ramp time of the first rate limit in S52. Accurate determination of this time is a prerequisite for ensuring that the response rates of the regenerative braking channel and the hydraulic damping channel are consistent.

[0171] In one embodiment, the hydraulic response time is determined by pre-calibration. This calibration is performed during the offline debugging phase of the device. For example, the control system sends a step control signal to the hydraulic control valve, while simultaneously collecting high-speed output data from the pressure or flow sensors of the hydraulic system. The system measures the time required from the signal sending time to the pressure or flow reaching its steady-state value (e.g. 90%), and records it as the hydraulic response time. This calibration process is repeated at different hydraulic oil temperatures and system pressures to generate a data table or lookup table describing the response time as a function of operating conditions.

[0172] In another embodiment, the hydraulic response time is determined by real-time identification. This identification is continuously performed during normal operation of the system. The system uses a system identification algorithm, such as the recursive least squares method, to continuously analyze the relationship between the compensated hydraulic control signal and the actual dynamic response. The algorithm calculates the dynamic parameters of the hydraulic control valve transfer function online, such as the time constant, and derives the current hydraulic response time from the parameters.

[0173] The pre-calibration method has the advantage of small real-time calculation amount, only table lookup, and low requirement for controller performance. Its disadvantage is that the model is static and cannot compensate for changes in working conditions outside the calibration range or response characteristic drift caused by valve wear or oil contamination. The real-time identification method has the advantage of dynamic adaptability, which can track changes in response time caused by system aging or wear, and maintain high synchronization accuracy. Its disadvantage is that the algorithm is complex and has high requirements for the real-time operation capability of the controller.

[0174] Further, S51 includes the following sub-steps S511-S514.

[0175] S511. In the equipment offline debugging stage, pre-calibration is performed; wherein the calibration process includes: at a plurality of preset hydraulic oil temperature points and a plurality of preset system pressure points, respectively measuring the actual dynamic response time of the hydraulic control valve.

[0176] S512. According to the calibration data obtained by pre-calibration, a multi-dimensional response time lookup table is established, wherein the response time lookup table stores the mapping relationship between hydraulic oil temperature, system pressure and hydraulic response time.

[0177] S513. When the system enters the real-time running stage, the real-time hydraulic oil temperature and the real-time system pressure are obtained.

[0178] S514. By querying the response time lookup table and combining the real-time hydraulic oil temperature and the real-time system pressure, the hydraulic response time under the current working condition is determined.

[0179] The pre-calibration process is carried out under controlled conditions. The control system fixes the system pressure and stabilizes the hydraulic oil temperature at the first preset hydraulic oil temperature point. Then, the system sends a step control signal to the hydraulic control valve and collects the feedback value of the pressure sensor at high speed, records the time consumed from signal sending to the actual pressure reaching the target value (e.g. 90%), which is the actual dynamic response time. The measurement process is repeated at all preset system pressure points. Subsequently, the system adjusts the oil temperature to the next preset hydraulic oil temperature point and repeats the measurement of all the above pressure points.

[0180] A multi-dimensional response time lookup table is established because the hydraulic response time is not a constant value, it will change significantly with the change of hydraulic oil temperature (affecting oil viscosity) and system pressure (affecting hydraulic power). The multi-dimensional response time lookup table (e.g. a three-dimensional lookup table) takes hydraulic oil temperature and system pressure as input axes and the measured actual dynamic response time as output value. The calibration data is filled in the corresponding grid points of the lookup table.

[0181] An example of setting the hydraulic response time for the mold plate braking of an injection molding machine. S511 is executed during the commissioning phase of the machine. The calibration procedure measures the hydraulic response time to be 120 ms at 30 degrees Celsius hydraulic oil temperature and 50 bar system pressure; 115 ms at 30 degrees Celsius and 100 bar; and 60 ms at 70 degrees Celsius and 150 bar. S512 stores these data in a response time lookup table. S513 acquires the real-time hydraulic oil temperature to be 60 degrees Celsius and the real-time system pressure to be 130 bar during an actual braking of the system (S2 and S4 steps). S514 uses these two real-time values to query the response time lookup table. Since the exact coordinate point (60, 130) was not directly calibrated, the system will calculate the hydraulic response time for the current operating condition, for example 78 ms, by executing a multidimensional interpolation algorithm between the neighboring data points in the lookup table (for example 60 ms at 70 degrees Celsius / 150 bar).

[0182] S52. Set the hydraulic response time as a target synchronization ramp time.

[0183] The target synchronization ramp time is a core configuration parameter of the ramp generator, which defines the time course for the regenerative braking command to increase linearly from its initial value to its target value. Setting the hydraulic response time as the target synchronization ramp time is a means to achieve dynamic synchronization control. The hydraulic damping channel requires the hydraulic response time to build up its full torque, and this step forces the torque build-up process of the regenerative braking channel to be completed in the same time. This matching ensures that the torques of the two channels grow at the same rate and reach their target values simultaneously, thus achieving smooth torque superposition.

[0184] Further, S52 includes the following sub-steps S521-S522.

[0185] S521. Receive the hydraulic response time value.

[0186] S522. Set the target synchronization ramp time parameter in the control register of the current braking cycle to the received hydraulic response time value.

[0187] The synchronization control logic module of the controller receives the hydraulic response time value, and the system writes the received hydraulic response time value into a specific parameter register in the motion controller or servo driver, which is the target synchronization ramp time parameter.

[0188] The instance of S514 is followed by S515, in which the hydraulic response time lookup table is queried and interpolated to calculate a hydraulic response time of 78 ms. The system receives this value of 78 ms and writes the value of 78 ms into a control register, from which a ramp generator will read the value as an execution parameter. If, in the next braking cycle, the hydraulic response time is determined to have changed to 82 ms due to a change in operating conditions, the control register is updated with the value of 82 ms. This step ensures that the ramp-up time used by the ramp generator is dynamically updated in each braking cycle to match the real-time operating conditions.

[0189] S53. configure the first rate limit as a ramp generator, the ramp-up time of the ramp generator being equal to the target synchronization ramp time.

[0190] A ramp generator is a standard functional block in servo drives or motion controllers. Its role is to receive a step change input signal, such as an instantaneously applied target torque command, and convert it into an output signal that rises or falls linearly over a specified time period. In this step, the ramp generator is used as a specific execution mechanism for the first rate limit. By setting the ramp-up time parameter to the target synchronization ramp time, this functional block forces the regenerative torque of the servo motor to be built smoothly over the same time period as the hydraulic response time, thus achieving the dynamic synchronization of S5 and S6.

[0191] Further, S53 comprises the following sub-steps S531-S532.

[0192] S531. access the ramp generator functional block in the servo drive or motion controller.

[0193] S532. dynamically update the configuration parameter of the ramp-up time of the ramp generator functional block to the target synchronization ramp time.

[0194] The control program of the motion controller accesses a specific parameter object, which is the ramp generator functional block integrated in the firmware of the servo drive or in the motion controller itself. The motion controller writes the value of the target synchronization ramp time stored in the control register to the configuration parameter of the ramp-up time of the ramp generator functional block via an internal bus or a fieldbus (e.g. SDO write operation of EtherCAT).

[0195] The instance of S514 is followed by S515, in which the hydraulic response time lookup table is queried and interpolated to calculate a hydraulic response time of 78 ms. The system receives this value of 78 ms and writes the value of 78 ms into a control register, from which a ramp generator will read the value as an execution parameter. If, in the next braking cycle, the hydraulic response time is determined to have changed to 82 ms due to a change in operating conditions, the control register is updated with the value of 82 ms. This step ensures that the ramp-up time used by the ramp generator is dynamically updated in each braking cycle to match the real-time operating conditions.

[0196] S54. The regenerative braking command is sent to the servo driver after being processed by the ramp generator.

[0197] Further, S54 comprises the following sub-steps S541-S544.

[0198] S541. The regenerative braking command is obtained.

[0199] S542. The regenerative braking command is input as the target value of the ramp generator.

[0200] S543. The ramp generator generates a time-smoothly rising intermediate command sequence according to the ramp-up time of the ramp generator.

[0201] S544. The intermediate command sequence is sent to the servo driver as the final running command.

[0202] The system obtains the regenerative braking command, i.e. the target regenerative torque. Take the example of S23, and assume that the value does not exceed the limit of S31, the target regenerative torque is -1250 N. The system inputs the value of -1250 N as the target value of the ramp generator. The ramp generator has been configured with a ramp-up time of 78 ms according to S532.

[0203] The ramp generator starts to generate a time-smoothly rising intermediate command sequence according to the ramp-up time of 78 ms at the synchronized time of S5 and S6. The starting value of the sequence is 0 N, which linearly increases to -1250 N within 78 ms. For example, at the 39th ms, the value of the intermediate command sequence is -625 N. The system sends the intermediate command sequence (0...-625...-1250) to the servo driver as the final running command in each control cycle. This process converts an instantaneous torque step command into a ramp command that matches the hydraulic response time (78 ms).

[0204] S6. The compensated hydraulic control signal is sent to the hydraulic control valve to realize dynamic synchronous control of the regenerative braking channel and the hydraulic damping channel.

[0205] The system sends the compensated hydraulic control signal to the hydraulic control valve. Take the example above, the signal is 3.6 V or 3.4 V determined by S445. This action activates the hydraulic damping channel, and the hydraulic control valve starts to respond to establish the hydraulic damping torque.

[0206] The sending time of the compensated hydraulic control signal is strictly synchronized with the starting time of the first rate limit. This synchronization ensures that the torque build-up process of the hydraulic damping channel and the torque build-up process of the regenerative braking channel start at the same time. The torque of the regenerative braking channel is smoothly rising within a target synchronization ramp time (e.g. 78ms). This design makes the torque of the two channels grow at the same rate (or a controlled, matched rate) at the same time, achieving dynamic synchronization control of the regenerative braking channel and the hydraulic damping channel, avoiding the instantaneous step or oscillation of the total braking torque.

[0207] Specifically, in some embodiments, S6 comprises the following sub-steps S61-S63.

[0208] S61. Send the compensated hydraulic control signal to the proportional relief valve or proportional throttle valve to start the hydraulic damping channel; wherein the hydraulic control valve is a proportional relief valve or a proportional throttle valve.

[0209] Both the proportional relief valve and the proportional throttle valve are hydraulic components that can continuously adjust the opening of their valve ports according to the input electronic signal (i.e. the compensated hydraulic control signal). The system sends the compensated hydraulic control signal to the valve. The signal drives the proportional electromagnet of the valve, causing the spool to move, thereby starting the hydraulic damping channel, allowing hydraulic oil to flow through the valve according to the opening corresponding to the signal.

[0210] Further, S61 comprises the following sub-steps S611-S614.

[0211] S611. Determine the hardware interface type of the hydraulic control valve, which includes analog current interface, analog voltage interface or field bus interface.

[0212] S612. Perform signal conversion on the compensated hydraulic control signal according to the hardware interface type.

[0213] S613. If the hardware interface type is an analog interface, the signal conversion includes converting the compensated hydraulic control signal into the corresponding digital-to-analog converter original value and outputting it through a digital-to-analog conversion channel.

[0214] S614. If the hardware interface type is a field bus interface, the signal conversion includes packaging the compensated hydraulic control signal into a data packet conforming to the field bus protocol and sending it through the field bus interface.

[0215] The system first determines the hardware interface type of the hydraulic control valve, such as an analog voltage interface or a fieldbus interface. This step provides the basis for subsequent signal conversion. The system performs signal conversion on the compensated hydraulic control signal according to the hardware interface type. This conversion step is necessary because it converts the digital logic signal generated internally by the motion controller (i.e., the compensated hydraulic control signal determined by S445) into a physical electrical signal or data signal that the hydraulic control valve hardware can receive and execute.

[0216] If the hardware interface type is an analog interface, such as a 0-10V voltage interface, signal conversion includes converting the compensated hydraulic control signal (e.g., 3.6V) into a corresponding digital-to-analog converter raw value (e.g., a 16-bit integer). This raw value is then output through a digital-to-analog conversion channel to generate a physical voltage of 3.6V at the interface end of the hydraulic control valve.

[0217] If the hardware interface type is a fieldbus interface, such as an EtherCAT bus, signal conversion includes packaging the compensated hydraulic control signal (3.6V) into a data packet that conforms to the fieldbus protocol, such as an EtherCAT process data object (PDO) packet. This packet is then sent to the hydraulic control valve through the fieldbus interface.

[0218] S62. Ensure that the sending time of the compensated hydraulic control signal is synchronized with the starting time of the first rate limit.

[0219] Further, S62 includes the following sub-steps S621-S624.

[0220] S621. Establish a high-precision, hardware-based distributed clock that is used to synchronize the I / O modules of the servo drive and the hydraulic control valve.

[0221] S622. Configure a clock synchronization task in the controller, and the execution period of the clock synchronization task is triggered by the distributed clock.

[0222] S623. Configure both the starting logic of the first rate limit and the sending logic of the compensated hydraulic control signal in the clock synchronization task.

[0223] S624. Start the first rate limit and send the compensated hydraulic control signal simultaneously within the same execution period of the clock synchronization task to eliminate task jitter and ensure synchronization between the sending time and the starting time.

[0224] This method establishes a high-precision, hardware-based distributed clock. This clock provides a unified time reference for the I / O modules of the servo drive and the hydraulic control valve. For example, the distributed clock (DC) mechanism of the EtherCAT bus can be used to synchronize all network nodes with the master clock to within nanoseconds.

[0225] The clock synchronization task configured in the controller is triggered by the distributed clock accurately, instead of the scheduler of the operating system. The start logic of the first rate limit and the sending logic of the compensated hydraulic control signal are both configured in the clock synchronization task.

[0226] In the same execution cycle of the clock synchronization task, the system starts the first rate limit and sends the compensated hydraulic control signal simultaneously. The purpose of this series of steps is to solve the problem of task jitter and hardware delay inside the controller. If this mechanism is not adopted, the start of the first rate limit may be executed in a 1 ms cycle of the motion task, while the sending of the compensated hydraulic control signal is executed in a 10 ms cycle of the I / O task, which will cause a deviation of several ms in the starting time of the two channels. This deviation will destroy the dynamic synchronization effect of S5 and re-introduce the brake shock. This step ensures that the instructions of the two channels are executed at the same physical time through the distributed clock and the clock synchronization task, eliminates the task jitter, and realizes high-precision start synchronization.

[0227] S63. The proportional relief valve or proportional throttle valve causes the hydraulic oil to generate a throttling loss according to the compensated hydraulic control signal, so as to realize the hydraulic damping torque.

[0228] The proportional relief valve or proportional throttle valve receives the compensated hydraulic control signal. In the foregoing example, the signal is 3.6 V. The signal drives the valve core of the valve to move to a specific opening degree, which is accurately corresponding to the 3.6 V signal. The load driven by the servo hydraulic system pushes the hydraulic oil under the brake inertia. The hydraulic oil is forced to flow through the specific opening degree formed by the valve core. The throttling effect occurs when the hydraulic oil flows through the restricted opening degree, which converts the kinetic energy of the load into heat energy, and this process is the throttling loss. The resistance generated by the energy conversion realizes the previously allocated hydraulic damping torque, for example, -1250 Newton.

[0229] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0230] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above.

[0231] The above examples are only used to illustrate the technical solutions of the present application, but not limit the present application; although the present application has been described in detail with reference to the foregoing examples, those ordinarily skilled in the art should understand: the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A hybrid brake control method for a servo hydraulic system, characterized by, The method comprises the following steps: S1. obtaining a total braking demand of a servo hydraulic system; wherein the total braking demand is a target braking torque determined by a motion controller for achieving a target deceleration process; S2. obtaining a real-time hydraulic oil temperature of the servo hydraulic system and a real-time state of charge of an energy storage device; based on the real-time hydraulic oil temperature and the real-time state of charge, a hierarchical decision algorithm is executed to distribute the total braking demand into a regenerative braking torque and a hydraulic damping torque; S3. converting the regenerative braking torque into a regenerative braking instruction; S4. based on the hydraulic damping torque, the real-time hydraulic oil temperature and a real-time system pressure, a preset compensation model is queried to determine a compensated hydraulic control signal; S5. sending the regenerative braking instruction to a servo driver and imposing a first rate limit on the regenerative braking instruction, which matches a dynamic response of the servo hydraulic system; S6. sending the compensated hydraulic control signal to a hydraulic control valve to achieve dynamic synchronous control of a regenerative braking channel and a hydraulic damping channel. The S2 comprises the following sub-steps: S21. presetting a critical temperature threshold, a warning temperature threshold, a first state of charge threshold group and a second state of charge threshold group; S22. comparing the real-time hydraulic oil temperature with the critical temperature threshold and comparing the real-time hydraulic oil temperature with the warning temperature threshold; when the real-time hydraulic oil temperature is greater than or equal to the critical temperature threshold, determining a regenerative factor as 1; when the real-time hydraulic oil temperature is less than the critical temperature threshold and greater than or equal to the warning temperature threshold, calculating the regenerative factor based on the real-time state of charge and the first state of charge threshold group; when the real-time hydraulic oil temperature is less than the warning temperature threshold, calculating the regenerative factor based on the real-time state of charge and the second state of charge threshold group; wherein a regenerative braking intervention state of charge interval defined by the first state of charge threshold group is higher than a regenerative braking intervention state of charge interval defined by the second state of charge threshold group; S23. calculating the regenerative braking torque and the hydraulic damping torque according to the determined regenerative factor and the total braking demand.

2. The hybrid brake control method of a servo hydraulic system according to claim 1, characterized by, The S1 comprises the following sub-steps: S11. monitoring a current motion state of the servo hydraulic system, wherein the current motion state comprises a current speed; S12. obtaining a target motion curve corresponding to the target deceleration process, wherein the target motion curve defines a target speed and a deceleration time; S13. obtaining a total inertia of a system driven by the servo hydraulic system; S14. calculating and determining the target braking torque according to the current motion state, the target motion curve and the total inertia of the system.

3. The hybrid brake control method of a servo hydraulic system according to claim 1, characterized by, The S3 comprises the following sub-steps: S31. obtaining a maximum regenerative torque limit of a servo motor corresponding to the servo driver; S32. comparing the regenerative braking torque with the maximum regenerative torque limit; S33. determining a target regenerative torque as a smaller value between the regenerative braking torque and the maximum regenerative torque limit; S34. converting the target regenerative torque into the regenerative braking instruction.

4. The hybrid brake control method of a servo hydraulic system according to claim 1, characterized by, The preset compensation model is a reference model; the reference model defines a target dynamic response corresponding to the hydraulic damping torque; The S4 includes the following sub-steps: S41. Real-time acquisition of the actual dynamic response of the hydraulic damping torque generated under the driving of the hydraulic control valve; S42. Real-time calculation of the identification error between the actual dynamic response and the target dynamic response; S43. Based on the identification error, the control gain parameter is adjusted in real time through a preset adaptive law; S44. Based on the hydraulic damping torque and the control gain parameter, the compensated hydraulic control signal is determined.

5. The hybrid brake control method of a servo hydraulic system according to claim 1, characterized by, The S5 includes the following sub-steps: S51. Pre-calibration or real-time identification of the dynamic response characteristics of the hydraulic control valve to determine a hydraulic response time; S52. Set the hydraulic response time as a target synchronization ramp time; S53. Configure the first rate limit as a slope generator, and the ramp-up time of the slope generator is equal to the target synchronization ramp time; S54. After the regenerative braking instruction is processed by the slope generator, it is sent to the servo driver.

6. The hybrid brake control method of a servo hydraulic system according to claim 1, characterized by, The S6 includes the following sub-steps: S61. Send the compensated hydraulic control signal to the proportional overflow valve or proportional throttle valve to start the hydraulic damping channel; wherein the hydraulic control valve is a proportional overflow valve or a proportional throttle valve; S62. Ensure that the sending time of the compensated hydraulic control signal is synchronized with the starting time of the first rate limit; S63. The proportional overflow valve or the proportional throttle valve generates throttling loss according to the compensated hydraulic control signal to realize the hydraulic damping torque.

7. The hybrid brake control method of a servo hydraulic system according to claim 4, characterized by, The S44 includes the following sub-steps: S441. Based on the hydraulic damping torque and the real-time adjusted control gain parameter, an intermediate hydraulic control signal is determined; S442. Pre-acquire the valve dead zone parameter and hysteresis loop parameter of the hydraulic control valve; S443. Apply a valve dead zone compensation to the intermediate hydraulic control signal, which is used to ensure that the hydraulic control valve starts to act when the intermediate hydraulic control signal is greater than the valve dead zone parameter; S444. According to the change direction of the intermediate hydraulic control signal, a hysteresis compensation is applied to the signal after the valve dead zone compensation, which is used to offset the influence of the hysteresis loop parameter; S445. The signal after the hysteresis compensation is determined as the compensated hydraulic control signal.

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