CN114439804B - Leveling system, leveling method and engineering machinery - Google Patents
Leveling system, leveling method and engineering machinery Download PDFInfo
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- CN114439804B CN114439804B CN202111664695.XA CN202111664695A CN114439804B CN 114439804 B CN114439804 B CN 114439804B CN 202111664695 A CN202111664695 A CN 202111664695A CN 114439804 B CN114439804 B CN 114439804B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/16—Special measures for feedback, e.g. by a follow-up device
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F11/00—Lifting devices specially adapted for particular uses not otherwise provided for
- B66F11/04—Lifting devices specially adapted for particular uses not otherwise provided for for movable platforms or cabins, e.g. on vehicles, permitting workmen to place themselves in any desired position for carrying out required operations
- B66F11/044—Working platforms suspended from booms
- B66F11/046—Working platforms suspended from booms of the telescoping type
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F17/00—Safety devices, e.g. for limiting or indicating lifting force
- B66F17/006—Safety devices, e.g. for limiting or indicating lifting force for working platforms
Abstract
The invention relates to the field of mechanical control, and discloses a leveling system, a leveling method and engineering machinery. The leveling system includes: the front control quantity acquisition device is used for acquiring the front control quantity of the leveling valve for controlling the platform according to the movement speed of the arm support and the movement speed of the platform; the leveling control quantity acquisition device is used for acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the front control quantity of the leveling valve, wherein the control quantity of the leveling valve comprises the feedforward control quantity and the feedback control quantity of the leveling valve; and the control device is used for controlling the leveling valve according to the control quantity of the leveling valve. The invention can carry out fine adjustment on the adjustment translation on the basis of feedforward control so as to adapt to working condition change, thereby eliminating leveling deviation caused by temperature, arm support deflection, load change and external interference of a hydraulic system.
Description
Technical Field
The invention relates to the field of mechanical control, in particular to a leveling system, a leveling method and engineering machinery.
Background
The aerial work platform is key equipment for serving movable aerial works such as aerial works in various industries, equipment installation and overhaul, wherein the leveling of the work platform not only directly influences the operation experience of operators, but also is closely related to the operation safety. Poor leveling control not only reduces the operating experience, but also causes the falling risk in severe cases. With the development of intelligent construction technology, higher requirements are put forward on the responsiveness, working condition adaptability and control accuracy of adjustment control.
The control parameters in the current leveling control are often fixed, and cannot be automatically adjusted according to different leveling working conditions, so that the control parameters are difficult to adapt to different arm frames and various working conditions after different speed combinations. In the application occasions with complex arm support movement relation (such as building printing), the control precision and stability are poor.
Disclosure of Invention
The invention aims to provide a leveling system, a leveling method and engineering machinery, which can perform fine adjustment on adjustment translation on the basis of feedforward control so as to adapt to working condition changes, thereby eliminating leveling deviation caused by temperature, arm support deflection, load change and external interference of a hydraulic system.
To achieve the above object, a first aspect of the present invention provides a leveling system comprising: the front control quantity acquisition device is used for acquiring the front control quantity of the leveling valve for controlling the platform according to the movement speed of the arm support and the movement speed of the platform; the leveling control quantity acquisition device is used for acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the front control quantity of the leveling valve, wherein the control quantity of the leveling valve comprises the feedforward control quantity and the feedback control quantity of the leveling valve; and the control device is used for controlling the leveling valve according to the control quantity of the leveling valve.
Preferably, the front control amount acquisition means includes: the arm support speed acquisition module is used for acquiring the movement speed of the arm support according to the control quantity of the hydraulic valve for controlling the movement of the arm support and a relation model between the control quantity of the hydraulic valve and the movement speed of the arm support; the platform speed acquisition module is used for acquiring the movement speed of the platform according to the movement speed of the arm support and a kinematic model between the movement speed of the arm support and the movement speed of the platform; and the front control quantity acquisition module is used for acquiring the front control quantity of the leveling valve according to the movement speed of the platform and a relation model between the front control quantity of the leveling valve and the movement speed of the platform.
Preferably, the relation model between the control amount of the hydraulic valve and the movement speed of the boom includes: and a nonlinear model between the control quantity of the hydraulic valve and the angular speed of the arm support.
Preferably, the control quantity of the hydraulic valve is the duty ratio of current, voltage, frequency and current on-off time or the duty ratio of voltage on-off time.
Preferably, the kinematic model between the motion speed of the boom and the motion speed of the platform comprises: and a kinematic model between the angular velocity of the arm support and the angular velocity of the platform.
Preferably, the leveling control amount acquisition means includes: the feedforward control quantity acquisition module is used for determining the feedforward control quantity of the leveling valve according to the prepositive control quantity of the leveling valve; the feedback control quantity acquisition module is used for determining the feedback control quantity of the leveling valve according to the working condition self-adaptive control algorithm, the front control quantity of the leveling valve and the leveling deviation, wherein the leveling deviation is an angle of the platform deviating from a horizontal plane; and the leveling control amount acquisition module is used for determining the control amount of the leveling valve according to the feedforward control amount of the leveling valve and the feedback control amount of the leveling valve.
Preferably, the feedforward control amount acquisition module is configured to determine a feedforward control amount of the leveling valve, including: and determining the product of the front control quantity of the leveling valve and a preset proportion as the feedforward control quantity of the leveling valve.
Preferably, the feedback control amount acquisition module is configured to determine the feedback control amount of the leveling valve, including: determining that the feedback control amount of the leveling valve is 0 under the condition that the front control amount of the leveling valve is 0 or the leveling deviation is smaller than a preset deviation; determining a feedback control amount of the leveling valve according to the leveling deviation and a first PID control strategy under the condition that the front control amount of the leveling valve becomes non-0 or the leveling deviation becomes larger than or equal to the preset deviation; determining a feedback control amount of the leveling valve according to the leveling deviation and a second PID control strategy when a front control amount of the leveling valve becomes non-0 and the duration exceeds the preset time or the leveling deviation is greater than or equal to the preset deviation and the duration exceeds the preset time; or determining the feedback control amount of the leveling valve according to the leveling deviation and a third PID control strategy under the condition that the front control amount of the leveling valve becomes 0 or the leveling deviation becomes smaller than the preset deviation.
Through the technical scheme, the front control quantity of the leveling valve for controlling the platform is creatively obtained according to the movement speed of the arm support and the movement speed of the platform; then, according to a working condition self-adaptive control algorithm and a front control quantity of the leveling valve, obtaining a control quantity of the leveling valve, wherein the control quantity of the leveling valve comprises a feedforward control quantity and a feedback control quantity of the leveling valve; and finally, controlling the leveling valve according to the control quantity of the leveling valve. Therefore, the invention can carry out fine adjustment on the adjustment translation on the basis of feedforward control so as to adapt to working condition change, thereby eliminating leveling deviation caused by temperature, deflection of the arm support, load change and external interference of a hydraulic system.
A second aspect of the present invention provides a leveling method comprising: acquiring a front control quantity of a leveling valve for controlling a platform according to the movement speed of the arm support and the movement speed of the platform; acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the front control quantity of the leveling valve, wherein the control quantity of the leveling valve comprises the feedforward control quantity and the feedback control quantity of the leveling valve; and controlling the leveling valve according to the control quantity of the leveling valve.
Specific details and benefits of the leveling method provided by the embodiments of the present invention can be found in the above description of the leveling system, and are not repeated here.
A third aspect of the present invention provides a construction machine comprising the leveling system.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention. In the drawings:
FIG. 1 is a schematic diagram of a leveling system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a boom according to an embodiment of the present invention;
FIG. 3 is a flow chart of a leveling process provided by an embodiment of the present invention;
FIG. 4 is a graph showing a relationship model between the angular velocity of the main arm and the control amount (i.e., valve control amount) of the hydraulic valve according to an embodiment of the present invention; and
FIG. 5 is a model of the relationship between the amount of forward control of a leveling valve (i.e., the valve control) and the angular velocity of a platform, in accordance with one embodiment of the present invention.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
Fig. 1 is a block diagram of a leveling system according to an embodiment of the present invention. As shown in fig. 1, the leveling system may include: the front control quantity acquisition device 10 is used for acquiring the front control quantity of the leveling valve for controlling the platform according to the movement speed of the arm support and the movement speed of the platform; the leveling control amount obtaining device 20 is configured to obtain a control amount of the leveling valve according to a working condition adaptive control algorithm and a front control amount of the leveling valve, where the control amount of the leveling valve includes a feedforward control amount and a feedback control amount of the leveling valve; and a control device 30 for controlling the leveling valve according to the control amount of the leveling valve.
The following describes the processes performed by the above-described front-end control amount acquisition device 10, leveling control amount acquisition device 20, and control device 30, respectively.
In an embodiment, the front control amount acquisition device 10 may include: the arm support speed acquisition module is used for acquiring the movement speed of the arm support according to the control quantity of the hydraulic valve for controlling the movement of the arm support and a relation model between the control quantity of the hydraulic valve and the movement speed of the arm support; the platform speed acquisition module is used for acquiring the movement speed of the platform according to the movement speed of the arm support and a kinematic model between the movement speed of the arm support and the movement speed of the platform; and the front control quantity acquisition module is used for acquiring the front control quantity of the leveling valve according to the movement speed of the platform and a relation model between the front control quantity of the leveling valve and the movement speed of the platform.
First, the process of acquiring the movement speed of the boom performed by the boom speed acquisition module is described as follows.
Wherein the relation model between the control amount of the hydraulic valve and the movement speed of the arm support can comprise: and a nonlinear model between the control quantity of the hydraulic valve and the angular speed of the arm support. The control quantity of the hydraulic valve can be the duty ratio of current, voltage, frequency and current on-off time or the duty ratio of voltage on-off time.
Taking the luffing motion of a main arm of a spider type aerial working platform as an example, the motion speed of the main arm is mainly influenced by the control quantity of corresponding hydraulic valves and the hinge point structure of the arm support. The variation of the angular velocity of the main arm caused by the same control amount variation can be up to 1 time different due to the nonlinear relation between the hydraulic valve and the angular velocity (i.e. the amplitude velocity) of the main arm. The hinge point structure of the main arm is usually a three-hinge point structure or a link structure. For the connecting rod type structure, the maximum speed difference generated by the same valve control amount (namely the control amount of the hydraulic valve) at different arm support positions is 6 times as large as that generated by the same valve control amount, and the speed difference is still 1-2 times after algorithm compensation. In general, the existing leveling control responds after the platform angle changes due to nonlinear factors such as a hydraulic valve, a boom structure and the like, and hysteresis exists in the control, so that user experience is affected.
In this embodiment, the specific relation model may be a data table, where the input is the control amount of the hydraulic valve and the boom angle, and the output is the angular velocity of the boom. The control quantity of the hydraulic valve is a control instruction of the angular speed of the arm support; and the boom angle is used to describe the boom position, and may refer to the absolute angle between the boom and the horizontal plane, or may refer to the relative angle between two adjacent sections of the boom (e.g., the tower arm angle refers to the angle between the tower arm and the horizontal plane; the main arm angle refers to the angle between the main arm and the tower arm; and the fly arm angle refers to the angle between the fly arm and the main arm). Specifically, a relation model between the control amount of the hydraulic valve and the boom angle and the angular velocity of the boom can be described by actually measured data. Taking the main arm of fig. 2 as an example, a specific relational model may be a data table, where the control amount of the hydraulic valve for controlling the main arm and the main arm angle (i.e., the angle between the main arm and the tower arm, for example) are input, and the output is the angular velocity of the main arm. Of course, a specific relationship model for the main arm may represent the relationship diagram shown in fig. 4.
For the boom (or fly arm) in the boom of fig. 2, the specific relationship model may be a data table, which is input as the control amount of the hydraulic valve for controlling the boom (or fly arm) and the boom (or fly arm) angle (i.e., the angle of the boom (or fly arm) to the horizontal plane) and output as the angular velocity of the boom (or fly arm).
For example, the data related to the relation model can be obtained through actual measurement by adopting a control variable method and a segmentation calibration method. For the section with obvious nonlinearity of the hydraulic valve and the position with larger speed change of the main arm, the number of sampling points is increased to approach the actual characteristic as much as possible. Therefore, the relationship model adopted in the embodiment reflects the speed change caused by the nonlinear factors of the hydraulic valve and the boom structure. According to the control instruction (namely, the control quantity of the hydraulic valve) for controlling the movement speed of the arm support, the movement speed of the arm support can be accurately estimated, so that stable and reliable input data can be provided for estimating the change of the movement speed of the platform and controlling a control valve (which can be simply called a leveling valve) for controlling the platform to level and timely follow the movement of the arm support.
When an operator sends out an operation instruction about the arm support, the arm support speed acquisition module can estimate the movement speed of the arm support according to the operation instruction, the main arm angle and the relation model. If the operator operates a plurality of arm support actions, the speed of each action is estimated.
In the embodiment, the nonlinear change of the leveling speed caused by factors such as a hydraulic system, a boom structure form and the like is described by using a relation model of the valve control quantity and the boom movement speed, and the nonlinear speed change is judged in advance because the relation model is input as an operation control instruction, so that an accurate and timely basis is provided for subsequent control. And then, the leveling valve (described in detail below) can be synchronously controlled according to the motion state of the boom estimated in advance, so that the influence of the boom motion on the platform angle can be timely and actively compensated. Thus, the leveling control is responsive quickly with little delay. Moreover, when the arm support is started, an operator does not feel that the platform sinks or warps, and the operation experience is good.
Next, a process of acquiring the movement speed of the platform performed by the platform speed acquisition module will be described. The movement speed of the platform refers to the movement speed of the platform caused by the leveling action of the leveling mechanism.
The kinematic model between the motion speed of the boom and the motion speed of the platform may include: and a kinematic model between the angular velocity of the arm support and the angular velocity of the platform. The angular speed of the platform refers to the angular change rate of the platform caused by the leveling action of the leveling mechanism.
In particular, the kinematic model between the angular velocity of the boom and the angular velocity of the platform may comprise: in the case of a boom comprising multiple sections of arms, the angular velocity of the platform is a function of the angular velocity of each section of arm and the set of structural coefficients of the luffing mechanism of each section of arm.
Taking a mixed arm support system (for example, comprising a main arm, a tower arm and a fly arm in fig. 2) of a spider type aerial working platform as an example, the mixed arm support system has an amplitude variation mechanism with a three-hinge-point structure and also has a multi-hinge-point connecting rod type amplitude variation mechanism, and meanwhile, a leveling mechanism of the platform is also a multi-hinge-point connecting rod type amplitude variation leveling mechanism (the platform is arranged on the leveling mechanism). Wherein, the motion of each luffing mechanism of the arm support has an influence on the included angle between the platform and the horizontal plane.
Specifically, the angle alpha between the platform and the horizontal plane p The determination can be made by the following formula:
α p ＝α 1 +α 2 +α 3 -α l ，
α 1 is the included angle between the main arm and the tower arm; alpha 2 Is the included angle between the tower arm and the horizontal plane; alpha 3 Is a fly armAn included angle of the main arm; alpha l Is the included angle between the platform and the fly arm.
The platform leveling aim is to adjust the included angle alpha between the platform and the fly jib when the tower jib, the main jib and the fly jib perform luffing motion l So that the angle alpha between the platform and the horizontal plane is p If 0, then there are:
α l ＝α 1 +α 2 +α 3 。 (1)
angular velocity omega of platform l Is the horizontal angle (alpha) of the platform l ) The rate of change, in combination with the above formula (1), can be represented by the following formula (2):
wherein, the liquid crystal display device comprises a liquid crystal display device,and->The angular velocities of the main arm, the tower arm and the fly arm are respectively. Specifically, the angular velocity of the main arm is the angular velocity of the main arm relative to the tower arm; the angular velocity of the tower arm is the angular velocity of the tower arm relative to the horizontal plane; the angular velocity of the fly arm is the angular velocity of the fly arm relative to the main arm.
In this embodiment, the luffing mechanism of the boom system is a three-hinge-point or multi-hinge-point link-type luffing mechanism, and the angular velocity of the boom and the velocity of the driving oil cylinder are in nonlinear change. Within the allowable range of the precision error of the platform, the relation between the angular velocity of each arm support and the velocity of the driving oil cylinder is as follows:
then according to the above formulas (2), (3)The method can obtain:
wherein { p } 11 、p 12 、p 13 }、{p 21 、p 22 、p 23 And { p } is 31 、p 32 、p 33 The structure coefficient sets of the luffing mechanisms of the main arm, the tower arm and the fly arm are respectively, wherein p is 1i 、p 2i 、p 3i The first structural coefficient, the second structural coefficient and the third structural coefficient of the luffing mechanism of each arm support i are respectively; andand->The angular velocities of the main arm, the tower arm and the fly arm are respectively.
In this embodiment, when the luffing mechanism of each boom is determined, the first structural coefficient, the second structural coefficient, and the third structural coefficient of the luffing mechanism of each boom may be determined, so that the kinematic model determined by the above formula (4) may be determined. Then, after the angular velocity of the boom is determined by detecting and controlling the output flow of the hydraulic valve bank in real time, the platform velocity obtaining module can determine the angular velocity of the platform by the above formula (4).
In the embodiment, a model of arm support movement speed and platform movement speed is used for describing complex relations between movement speeds of different arm supports and platform movement speeds. The complex boom movement caused by complex working conditions is simplified into the change of the platform movement speed, and a foundation is provided for ensuring that leveling control adapts to complex and variable working conditions. Therefore, the problems of overshoot and oscillation easily occurring in leveling control caused by various structural forms of the arm frame, uncertain operation combination, complex and changeable arm frame movement and the like can be solved.
Finally, a procedure of acquiring the front control amount of the leveling valve, which is executed by the front control amount acquisition module, will be described.
Because the relation between the control signal for controlling the leveling valve of the platform and the movement speed of the platform is a nonlinear relation, the valve control amount required for maintaining the movement speed of the platform can be calculated back through a relation model between the front control amount of the leveling valve and the movement speed of the platform (for example, the change rate of the included angle of the platform relative to the fly jib, namely, the angular speed of the platform). Specifically, a negative value of the movement speed of the platform (i.e. the same magnitude as the movement speed but opposite in direction) is taken, a relation model between the front control amount of the leveling valve and the movement speed of the platform is introduced, and the front control amount obtaining module can obtain the front control amount of the leveling valve. Therefore, the horizontal angle change of the platform caused by the arm support movement can be counteracted by the obtained front control quantity of the leveling valve, so that the stable and reliable leveling control of the working platform is realized.
In this embodiment, the specific relation model may be a data table, where the input is the movement speed of the platform and the output is the front control amount of the leveling valve. For example, the data related to the relation model can be obtained through actual measurement by adopting a control variable method and a segmentation calibration method. For the section with obvious nonlinearity of the leveling valve and the position with large motion speed change of the platform, the number of sampling points is increased to approach the actual characteristic as much as possible. Thus, the relationship model employed in this embodiment reflects the speed change caused by the nonlinear factor of the leveling valve. The control command (namely the front control quantity of the leveling valve) for controlling the leveling valve can be accurately estimated according to the movement speed of the platform, so that the platform can be subjected to real-time leveling control according to the front control quantity of the leveling valve. Of course, a specific relationship model for the leveling valve may represent the relationship diagram shown in fig. 5.
Of course, in another embodiment, the front control amount acquisition means includes: the arm support speed acquisition module is used for acquiring the movement speed of the arm support by acquiring the angle of the arm support; the platform speed acquisition module is used for acquiring the movement speed of the platform through acquiring the angle of the platform; and the front control quantity acquisition module is used for acquiring the front control quantity of the leveling valve according to the movement speed of the platform and a relation model between the front control quantity of the leveling valve and the movement speed of the platform.
In an embodiment, the leveling control amount acquisition device 20 may include: the feedforward control quantity acquisition module is used for determining the feedforward control quantity of the leveling valve according to the prepositive control quantity of the leveling valve; the feedback control quantity acquisition module is used for determining the feedback control quantity of the leveling valve according to the working condition self-adaptive control algorithm, the front control quantity of the leveling valve and the leveling deviation, wherein the leveling deviation is an angle of the platform deviating from a horizontal plane; and the leveling control amount acquisition module is used for determining the control amount of the leveling valve according to the feedforward control amount of the leveling valve and the feedback control amount of the leveling valve.
In an embodiment, the feedforward control amount acquisition module for determining the feedforward control amount of the leveling valve may include: and determining the product of the front control quantity of the leveling valve and a preset proportion as the feedforward control quantity of the leveling valve.
Specifically, the control amount P can be controlled according to the front of the leveling valve level And the following formula (5), calculate the feedforward control amount P Forwad ：
P Forwad ＝Kf*P level ， (5)
Where Kf is a feedforward control coefficient, which is used to adjust the degree of feedforward control (for example, it may take a value of 1).
The embodiment takes the speed control instruction as input, and the speed of the arm support movement can be estimated in advance without the arm support movement, so that the leveling valve can be controlled to follow the arm support movement in time; and the estimated arm support movement speed is only influenced by the valve control quantity, and the fluctuation is small, so that the trend of the arm support movement can be accurately reflected. The determined feedforward control quantity can be used as a basic value of leveling control, has the characteristics of quick response and advanced control, and can timely control the platform to move along with the arm support. The working condition self-adaptive control algorithm carries out fine adjustment on the adjustment translation on the basis of feedforward control, and eliminates leveling deviation caused by temperature, arm support deflection, load change and external interference of a hydraulic system.
The front control quantity of the leveling valve is calculated according to the control instruction of the boom speed, so that the leveling valve can be synchronously opened with the hydraulic valve of the boom, and the platform can timely follow the boom to move. The nonlinear change of the speed caused by the factors such as the hydraulic system, the boom structure and the like can be directly included in the front control quantity of the leveling valve through two models (a relation model of the control quantity of the hydraulic valve and the boom movement speed and a kinematic model of the boom movement speed and the platform movement speed). This is equivalent to compensating for the variation in the angle of the platform caused by the boom movement speed, so that the variation in the angle of the platform caused by nonlinear factors can be effectively suppressed. However, the system still has the influence of factors such as the temperature of a hydraulic system, deflection of an arm support, load change and the like, and the error of leveling control cannot be ensured only through feedforward control.
In one embodiment, the feedback control amount acquisition module is configured to determine the feedback control amount of the leveling valve, including: determining that the feedback control amount of the leveling valve is 0 under the condition that the front control amount of the leveling valve is 0 or the leveling deviation is smaller than a preset deviation; determining a feedback control amount of the leveling valve according to the leveling deviation and a first PID control strategy under the condition that the front control amount of the leveling valve becomes non-0 or the leveling deviation becomes larger than or equal to the preset deviation; determining a feedback control amount of the leveling valve according to the leveling deviation and a second PID control strategy when a front control amount of the leveling valve becomes non-0 and the duration exceeds the preset time or the leveling deviation is greater than or equal to the preset deviation and the duration exceeds the preset time; or determining the feedback control amount of the leveling valve according to the leveling deviation and a third PID control strategy under the condition that the front control amount of the leveling valve becomes 0 or the leveling deviation becomes smaller than the preset deviation.
The present embodiment divides the leveling process into four phases: a waiting phase, a start phase, a conditioning phase and a stop phase.
Feedback control amount f (P) Forward E) represents a control amount determined by a feedforward control amount (which depends on a pre-control amount of the leveling valve) and a leveling deviation. Specifically, according to the change of the feedforward control quantity of the leveling valve (which depends on the front control quantity of the leveling valve), the stage of the leveling working condition can be accurately estimated; in each stage, e is taken as an input of the corresponding PID control, and the feedback control quantity is taken as an output of the corresponding PID control (specific parameters in the PID control strategies adopted in each stage are different). That is, f (P Forward E) is a piecewise function.
Waiting phase: when the front control amount of the leveling valve is equal to 0 or the leveling deviation is smaller than the preset deviation, the waiting stage is indicated. F (P) of working condition self-adaptive output at this stage Forward E) is 0, and the changes of the front control quantity and the leveling deviation of the leveling valve are circularly detected.
A starting stage: and when the front control quantity of the leveling valve is not equal to 0 or the leveling deviation is greater than or equal to the preset deviation, indicating that the starting stage is entered. At this stage, the leveling deviation is taken as input, and f (P) is output according to the first PID control strategy Forward ,e)。
And, the main task of the start-up phase is to open the leveling valve quickly and track the boom movement in time. Because the leveling valve sends out a control command to the leveling action, the time difference exists and is influenced by the valve control quantity, the control strategy in the starting stage is as follows: leveling is started at the fastest speed, but without causing abrupt changes in platform angle. The length of the start-up phase is regulated by a parameter, the start-up time, which may be determined based on the characteristics of the leveling valve (e.g., may take on a reasonable constant).
For the first PID control strategy, this stage is expected to allow the hydraulic valve to open quickly, tracking boom movement in time, so the P parameter will be set relatively large. Because there is a delay from the opening of the hydraulic valve to the change of the leveling angle, the I parameter is set to be smaller or even 0.
And (3) adjusting: and when the front control quantity of the leveling valve is not equal to 0 and the maintaining time exceeds the preset starting time, or when the leveling deviation is greater than or equal to the preset deviation and the maintaining time exceeds the preset starting time (namely, the starting phase is ended), indicating that the leveling phase is entered. At this stage, will levelThe deviation is taken as input and f (P Forward ,e)。
For the second PID control strategy, it is desirable that the leveling action be smooth at this stage to improve operator comfort, so the P parameter is set to be relatively small to reduce the fluctuation of the platform angle. To eliminate tracking errors, the I parameter is set larger to enhance the integration effect, thereby keeping the work platform level.
Stopping: and when the front control quantity of the leveling valve is equal to 0 again or the leveling deviation is smaller than the preset deviation again, indicating that the stopping stage is started. The main purpose of the stopping stage is to eliminate the integral accumulation value generated by the PID control, and prevent the vibration adjustment of the working platform after the arm support movement is stopped. At this stage, the leveling deviation is taken as input and the output f (P) is output according to a third PID control strategy (wherein the integral cumulative value can be set to 0) Forward ，e)。
For the third PID control strategy, because of hysteresis of the hydraulic valve, parameters different from the starting phase are adopted at the stage, the general P parameter is smaller than the starting phase and larger than the adjusting phase, and the I parameter is zero. In addition, to prevent saturation of the integration, an integration zero-out strategy is adopted at the end of this phase.
The first PID control strategy, the second PID control strategy and the third PID control strategy are different in control parameters. The specific PID control process can be performed according to the prior art, and will not be described in detail herein.
On the basis that the feedforward control ensures timely response of the leveling control, the staged control of the feedback control quantity can eliminate leveling errors caused by factors such as temperature, arm support deflection, load change, external interference and the like of a hydraulic system, and can avoid platform angle oscillation caused by conventional PID control, so that the control precision is greatly improved.
In one embodiment, the feed-forward control amount P of the leveling valve is based on Forward Feedback control amount f (P Forward E), the leveling control amount acquisition module may determine a control amount P of the leveling valve expressed by the following formula adapt ，
P adapt ＝P Forward +f(P Forward ，e)， (6)
Accordingly, the control device 30 can control the control amount P of the leveling valve according to the above determination adapt And controlling the leveling valve to operate.
In the existing leveling control process with hysteresis, the leveling valve needs to be frequently operated (opened/closed) due to nonlinear change of the arm support movement speed, so that leveling control experience is poor. On the basis that feedforward control ensures that the platform actively moves with the arm support to eliminate the influence of nonlinear factors on the angle of the platform, the embodiment automatically adapts to the change of working conditions through feedback control, and can greatly reduce the switching frequency of the leveling valve, thereby ensuring the stable operation of the working platform.
Specifically, the adjustment process will be described by taking the flow shown in fig. 3 as an example.
As shown in fig. 3, the leveling process may include the following steps S301-S305.
Step S301, according to a control command of the hydraulic valve and the first relation model, the movement speed of the arm support is obtained.
The first relation model is a relation model between the control quantity of the hydraulic valve and the movement speed of the arm support.
Step S302, according to the motion speed of the arm support and the kinematic model, the motion speed of the platform is obtained.
The kinematic model is a kinematic model between the motion speed of the arm support and the motion speed of the platform.
Step S303, obtaining the front control quantity of the leveling valve according to the movement speed of the platform and the second relation model.
The second relation model is used for controlling the relation model between the prepositive control quantity of the leveling valve of the platform and the movement speed of the platform.
And step S304, obtaining the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the front control quantity of the leveling valve.
The control quantity of the leveling valve comprises a feedforward control quantity and a feedback control quantity of the leveling valve.
And step S305, controlling the leveling valve according to the control quantity of the leveling valve.
In the invention, unless otherwise specified, the movement speed of the platform refers to the movement speed of the platform caused by the leveling action of the leveling mechanism; the angular speed of the platform refers to the angular change rate of the platform caused by the leveling action of the leveling mechanism, so that the movement speed of the platform can be replaced with the leveling movement speed of the platform; the "angular velocity of the platform" is interchangeable with the "leveling angular velocity of the platform".
In summary, the invention creatively obtains the front control quantity of the leveling valve for controlling the platform according to the movement speed of the arm support and the movement speed of the platform; then, according to a working condition self-adaptive control algorithm and a front control quantity of the leveling valve, obtaining a control quantity of the leveling valve, wherein the control quantity of the leveling valve comprises a feedforward control quantity and a feedback control quantity of the leveling valve; and finally, controlling the leveling valve according to the control quantity of the leveling valve. Therefore, the invention can carry out fine adjustment on the adjustment translation on the basis of feedforward control so as to adapt to working condition change, thereby eliminating leveling deviation caused by temperature, deflection of the arm support, load change and external interference of a hydraulic system.
The embodiment of the invention also provides a leveling method. The leveling method may include: acquiring a front control quantity of a leveling valve for controlling a platform according to the movement speed of the arm support and the movement speed of the platform; acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the front control quantity of the leveling valve, wherein the control quantity of the leveling valve comprises the feedforward control quantity and the feedback control quantity of the leveling valve; and controlling the leveling valve according to the control quantity of the leveling valve.
Specific details and benefits of the leveling method provided by the embodiments of the present invention can be found in the above description of the leveling system, and are not repeated here.
The embodiment of the invention also provides engineering machinery, which comprises the leveling system. Wherein, the engineering machinery can be high-altitude operation equipment.
Specific details and benefits of the engineering machine provided by the embodiments of the present invention can be found in the above description of the leveling system, and are not repeated here.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
Claims (9)
1. A leveling system, the leveling system comprising:
the front control quantity acquisition device is used for acquiring the front control quantity of the leveling valve for controlling the platform according to the movement speed of the arm support and the movement speed of the platform;
the leveling control quantity acquisition device is used for acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the front control quantity of the leveling valve, wherein the control quantity of the leveling valve comprises the feedforward control quantity and the feedback control quantity of the leveling valve; and
a control device for controlling the leveling valve according to the control amount of the leveling valve,
wherein the front control amount acquisition device includes:
the arm support speed acquisition module is used for acquiring the movement speed of the arm support according to the control quantity of the hydraulic valve for controlling the movement of the arm support and a relation model between the control quantity of the hydraulic valve and the movement speed of the arm support;
the platform speed acquisition module is used for acquiring the movement speed of the platform according to the movement speed of the arm support and a kinematic model between the movement speed of the arm support and the movement speed of the platform; and
the front control quantity acquisition module is used for acquiring the front control quantity of the leveling valve according to the movement speed of the platform and a relation model between the front control quantity of the leveling valve and the movement speed of the platform.
2. The leveling system of claim 1, wherein the model of the relationship between the control amount of the hydraulic valve and the velocity of movement of the boom comprises: and a nonlinear model between the control quantity of the hydraulic valve and the angular speed of the arm support.
3. The leveling system of claim 1, wherein the control amount of the hydraulic valve is a current, a voltage, a frequency, a duty cycle of a current on-off time, or a duty cycle of a voltage on-off time.
4. The leveling system of claim 1, wherein the kinematic model between the velocity of motion of the boom and the velocity of motion of the platform comprises: and a kinematic model between the angular velocity of the arm support and the angular velocity of the platform.
5. The leveling system according to claim 1, wherein the leveling control amount acquisition means includes:
the feedforward control quantity acquisition module is used for determining the feedforward control quantity of the leveling valve according to the prepositive control quantity of the leveling valve;
the feedback control quantity acquisition module is used for determining the feedback control quantity of the leveling valve according to the working condition self-adaptive control algorithm, the front control quantity of the leveling valve and the leveling deviation, wherein the leveling deviation is an angle of the platform deviating from a horizontal plane; and
and the leveling control quantity acquisition module is used for determining the control quantity of the leveling valve according to the feedforward control quantity of the leveling valve and the feedback control quantity of the leveling valve.
6. The leveling system of claim 5, wherein the feedforward control amount acquisition module to determine the feedforward control amount of the leveling valve comprises:
and determining the product of the front control quantity of the leveling valve and a preset proportion as the feedforward control quantity of the leveling valve.
7. The leveling system of claim 5, wherein the feedback control amount acquisition module for determining the feedback control amount of the leveling valve comprises:
determining that the feedback control amount of the leveling valve is 0 under the condition that the front control amount of the leveling valve is 0 or the leveling deviation is smaller than a preset deviation;
determining a feedback control amount of the leveling valve according to the leveling deviation and a first PID control strategy under the condition that the front control amount of the leveling valve becomes non-0 or the leveling deviation becomes larger than or equal to the preset deviation;
determining a feedback control amount of the leveling valve according to the leveling deviation and a second PID control strategy when the front control amount of the leveling valve becomes non-0 and the duration exceeds a preset time or the leveling deviation is greater than or equal to the preset deviation and the duration exceeds the preset time; or alternatively
And determining the feedback control quantity of the leveling valve according to the leveling deviation and a third PID control strategy under the condition that the front control quantity of the leveling valve becomes 0 or the leveling deviation becomes smaller than the preset deviation.
8. A leveling method, characterized in that the leveling method comprises:
acquiring a front control quantity of a leveling valve for controlling a platform according to the movement speed of the arm support and the movement speed of the platform;
acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the front control quantity of the leveling valve, wherein the control quantity of the leveling valve comprises the feedforward control quantity and the feedback control quantity of the leveling valve; and
controlling the leveling valve according to the control quantity of the leveling valve,
wherein, according to the motion speed of the arm support and the motion speed of the platform, the obtaining the front control quantity of the leveling valve for controlling the platform comprises the following steps:
acquiring the movement speed of the arm support according to the control quantity of the hydraulic valve for controlling the movement of the arm support and a relation model between the control quantity of the hydraulic valve and the movement speed of the arm support;
acquiring the motion speed of the platform according to the motion speed of the arm support and a kinematic model between the motion speed of the arm support and the motion speed of the platform; and
and acquiring the front control quantity of the leveling valve according to the movement speed of the platform and a relation model between the front control quantity of the leveling valve and the movement speed of the platform.
9. A working machine, characterized in that it comprises a leveling system according to any one of claims 1-7.
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