CN114439804A - Leveling system, leveling method and engineering machinery - Google Patents
Leveling system, leveling method and engineering machinery Download PDFInfo
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- CN114439804A CN114439804A CN202111664695.XA CN202111664695A CN114439804A CN 114439804 A CN114439804 A CN 114439804A CN 202111664695 A CN202111664695 A CN 202111664695A CN 114439804 A CN114439804 A CN 114439804A
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- control quantity
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- leveling valve
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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 machine control, and discloses a leveling system, a leveling method and engineering machinery. The leveling system includes: the device comprises a preposed control quantity acquisition device, a leveling valve control device and a control device, wherein the preposed control quantity acquisition device is used for acquiring a preposed control quantity of the leveling valve used for controlling the platform according to the movement speed of the arm support and the movement speed of the platform; the leveling control quantity obtaining device is used for obtaining the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the preposed 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 the control device is used for controlling the leveling valve according to the control quantity of the leveling valve. The invention can adjust the translation finely to adapt to the working condition change on the basis of feed forward control, thereby eliminating the leveling deviation caused by the temperature of a hydraulic system, the deflection of the arm support, the load change and the external interference.
Description
Technical Field
The invention relates to the field of machine control, in particular to a leveling system, a leveling method and engineering machinery.
Background
The aerial work platform is key equipment for serving mobile aerial work such as aerial work, equipment installation and maintenance in various industries, wherein the leveling of the working platform not only directly influences the operation experience of operating personnel, but also is closely related to the operation safety. Poor leveling control not only reduces the operational experience but also can cause a fall risk in severe cases. With the development of intelligent construction technology, higher requirements are provided for the responsiveness, working condition adaptability and control precision of leveling 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. The control precision and stability of the arm support are poor in the application occasions (such as building printing) with complex arm support motion relation.
Disclosure of Invention
The invention aims to provide a leveling system, a leveling method and engineering machinery, which can be used for finely adjusting the translation adjusting action to adapt to the working condition change on the basis of feed forward control, so that the leveling deviation caused by the temperature of a hydraulic system, the deflection of an arm support, the load change and external interference is eliminated.
In order to achieve the above object, a first aspect of the present invention provides a leveling system comprising: the device comprises a preposed control quantity acquisition device, a leveling valve control device and a control device, wherein the preposed control quantity acquisition device is used for acquiring a preposed control quantity of the leveling valve used for controlling the platform according to the movement speed of the arm support and the movement speed of the platform; the leveling control quantity obtaining device is used for obtaining the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the preposed 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 the control device is used for controlling the leveling valve according to the control quantity of the leveling valve.
Preferably, the advanced control amount acquisition means includes: the boom speed acquisition module is used for acquiring the movement speed of the boom according to the control quantity of a hydraulic valve for controlling the movement of the boom and a relation model between the control quantity of the hydraulic valve and the movement speed of the boom; the platform speed acquisition module is used for 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 the preposed control quantity acquisition module is used for acquiring the preposed control quantity of the leveling valve according to the motion speed of the platform and a relation model between the preposed control quantity of the leveling valve and the motion speed of the platform.
Preferably, the relationship model between the control quantity of the hydraulic valve and the movement speed of the boom includes: a non-linear model between a control quantity of the hydraulic valve and an angular velocity of the boom.
Preferably, the control quantity of the hydraulic valve is current, voltage, frequency, duty ratio of current on-off time or duty ratio of voltage on-off time.
Preferably, the kinematic model between the movement speed of the boom and the movement speed of the platform includes: a kinematic model between the angular velocity of the boom 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 preposed 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 preposed control quantity of the leveling valve and the leveling deviation, wherein the leveling deviation is the angle of the platform deviating from the horizontal plane; 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.
Preferably, the feedforward control amount acquisition module for determining the feedforward control amount of the leveling valve includes: and determining the product of the pre-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 for determining the feedback control amount of the leveling valve includes: determining the feedback control quantity of the leveling valve to be 0 under the condition that the prepositive control quantity of the leveling valve is 0 or the leveling deviation is smaller than the preset deviation; determining the feedback control quantity of the leveling valve according to the leveling deviation and a first PID control strategy under the condition that the pre-control quantity of the leveling valve is not 0 or the leveling deviation is greater than or equal to the preset deviation; under the condition that the pre-control quantity of the leveling valve becomes non-0 and the duration time exceeds the preset time or the leveling deviation is greater than or equal to the preset deviation and the duration time exceeds the preset time, determining the feedback control quantity of the leveling valve according to the leveling deviation and a second PID control strategy; or 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 preposed control quantity of the leveling valve becomes 0 or the leveling deviation becomes smaller than the preset deviation.
Through the technical scheme, the invention creatively obtains the preposed 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, acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the pre-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 translation adjusting action on the basis of feed forward control so as to adapt to the working condition change, thereby eliminating the leveling deviation caused by the temperature of a hydraulic system, the deflection of the arm support, the load change and the external interference.
The invention provides a leveling method in a second aspect, which comprises the following steps: acquiring a preposed 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 preposed 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 controlling the leveling valve according to the control quantity of the leveling valve.
For details and benefits of the leveling method provided by the embodiment of the present invention, reference may be made to the above description of the leveling system, and further description is omitted here.
A third aspect of the invention provides a working machine comprising said levelling system.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic structural diagram of a leveling system provided in one embodiment of the present invention;
fig. 2 is a schematic structural diagram of an arm support 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 model of the relationship between the angular velocity of the main arm and the control amount (i.e., the 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 pilot control amount (i.e., the valve control amount) of the leveling valve and the angular velocity of the stage according to an embodiment of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
Fig. 1 is a block diagram of a leveling system provided in an embodiment of the present invention. As shown in fig. 1, the leveling system may include: the device for acquiring the preposed control quantity is used for acquiring the preposed control quantity of a 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 obtaining device 20 is configured to obtain a control quantity of the leveling valve according to a working condition adaptive control algorithm and a pre-control quantity of the leveling valve, where the control quantity of the leveling valve includes a feedforward control quantity and a feedback control quantity of the leveling valve; and a control device 30 for controlling the leveling valve according to a control amount of the leveling valve.
The following describes the processes performed by the aforementioned pre-control amount acquisition device 10, leveling control amount acquisition device 20, and control device 30.
In one embodiment, the advanced control amount acquisition device 10 may include: the boom speed acquisition module is used for acquiring the movement speed of the boom according to the control quantity of a hydraulic valve for controlling the movement of the boom and a relation model between the control quantity of the hydraulic valve and the movement speed of the boom; the platform speed acquisition module is used for 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 the preposed control quantity acquisition module is used for acquiring the preposed control quantity of the leveling valve according to the motion speed of the platform and a relation model between the preposed control quantity of the leveling valve and the motion speed of the platform.
First, a process of acquiring the movement speed of the boom, which is performed by the boom speed acquisition module, is described as follows.
Wherein the relationship model between the control quantity of the hydraulic valve and the movement speed of the boom may include: a non-linear model between a control quantity of the hydraulic valve and an angular velocity of the boom. The control quantity of the hydraulic valve can be current, voltage, frequency, duty ratio of current on-off time or duty ratio of voltage on-off time.
Taking the amplitude variation of the main arm of a certain spider-type aerial work platform as an example, the action speed of the main arm is mainly influenced by the control quantity of a corresponding hydraulic valve and the hinge point structure of the arm support. Due to the non-linear relationship between the hydraulic valve and the angular velocity (i.e., the luffing velocity) of the main arm, the angular velocity variation of the main arm caused by the same control amount variation can differ by up to 1 time. The hinge point structure of the main arm is usually a three-hinge point structure or a link structure. For the link structure, the maximum speed difference generated by the same valve control amount (i.e. the control amount of the hydraulic valve) at different boom positions is more than 6 times, and the speed difference is still 1-2 times after algorithm compensation. Generally, the existing leveling control responds after the angle of a platform is changed due to non-linear factors such as a hydraulic valve and an arm support structure, and the control has hysteresis, so that the user experience is influenced.
In this embodiment, the specific relationship model may be a data table, which is input as the control quantity of the hydraulic valve and the angle of the arm support, and output as the angular velocity of the arm support. The control quantity of the hydraulic valve is a control instruction of the angular speed of the arm support; the arm support angle is used for describing the position of the arm support, and can refer to an absolute included angle between the arm support and a horizontal plane, and also can refer to a relative angle between two adjacent sections of arms in the arm support (for example, a tower arm angle refers to an included angle between a tower arm and the horizontal plane, a main arm angle refers to an included angle between the main arm and the tower arm, and a fly arm angle refers to an included angle between a fly arm and the main arm). Specifically, a relation model between both the control quantity of the hydraulic valve and the boom angle and the angular velocity of the boom can be described by the measured data. Taking the main arm of fig. 2 as an example, the specific relationship model may be a data table, which has as inputs the control quantity of the hydraulic valve for controlling the main arm and the angle of the main arm (i.e., the angle between the main arm and the tower arm, for example), and has as output the angular velocity of the main arm. Of course, the specific relationship model for the master arm may represent the relationship diagram shown in fig. 4.
For the tower arm (or fly arm) in the arm support in fig. 2, the specific relationship model may be a data table, which is input as the control quantity of the hydraulic valve for controlling the tower arm (or fly arm) and the angle of the tower arm (or fly arm) (i.e. the included angle between the tower arm (or fly arm) and the horizontal plane), and output as the angular velocity of the tower arm (or fly arm).
For example, the data related to the relational model can be obtained through actual measurement by adopting a control variable method and a segmented calibration method. For the section with obvious nonlinearity of the hydraulic valve and the position with large speed change of the main arm, the number of sampling points is increased, and the actual characteristic is approached as much as possible. Therefore, the relation model adopted in the embodiment reflects the speed change caused by the non-linear factors of the hydraulic valve and the arm support structure. According to a control instruction (namely the control quantity of a hydraulic valve) for controlling the movement speed of the arm support, the movement speed of the arm support can be accurately predicted, so that stable and reliable input data can be provided for predicting the change of the movement speed of the platform and controlling a control valve (which can be called as a leveling valve for short) for controlling the leveling of the platform to timely follow the movement of the arm support.
When an operator sends 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 angle of the main arm and the relation model. If the operator operates a plurality of arm supports to act, the speed of each action is estimated.
In the embodiment, the relationship model of the valve control quantity and the boom movement speed is used for describing the nonlinear change of the leveling speed caused by factors such as a hydraulic system and the boom structure form, and the input of the relationship model is an operation control instruction, so that the nonlinear speed change is judged in advance, and accurate and timely basis is provided for subsequent control. And then, synchronously controlling a leveling valve (see the content in the following) according to the motion state of the arm support estimated in advance, and actively compensating the influence of the arm support motion on the platform angle in time. Thus, the leveling control responds quickly with little delay. And when the arm support is started, the operator does not feel that the platform sinks or tilts up, and the operation experience is good.
Next, a process of acquiring the movement velocity of the platform performed by the platform velocity 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 movement speed of the boom and the movement speed of the platform may include: a kinematic model between the angular velocity of the boom and the angular velocity of the platform. The angular velocity of the platform refers to an angular change rate of the platform caused by a leveling action of the leveling mechanism.
Specifically, the kinematic model between the angular velocity of the boom and the angular velocity of the platform may include: in the case that the boom comprises a plurality of sections of arms, the angular velocity of the platform is a function of the angular velocity of each section of arm and a set of structural coefficients of the luffing mechanism of each section of arm.
Taking a hybrid boom system (for example, which includes a main arm, a tower arm and a fly jib in fig. 2) of a certain spider-type aerial work platform as an example, the hybrid boom system has both a luffing mechanism with a three-hinge-point structure and a multi-hinge-point connecting rod type luffing mechanism, and meanwhile, a leveling mechanism of the platform is also a multi-hinge-point connecting rod type luffing leveling mechanism (the platform is mounted 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.
In particular, the angle α between the platform and the horizontal planepCan be determined by the following formula:
αp＝α1+α2+α3-αl，
α1is the included angle between the main arm and the tower arm; alpha is alpha2Is the included angle between the tower arm and the horizontal plane; alpha is alpha3The included angle between the fly arm and the main arm is formed; alpha is alphalIs the included angle between the platform and the fly arm.
The aim of the platform leveling 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 amplitude variation actionlSo that the platform forms an angle alpha with the horizontal plane p0, then there are:
αl＝α1+α2+α3。 (1)
angular velocity ω of the platformlIs the horizontal angle (alpha) of the platforml) The rate of change, in combination with the above formula (1), can be represented by the following formula (2):
wherein the content of the first and second substances,
and
the angular velocities of the main arm, the tower arm and the fly jib respectively. Specifically, the angular velocity of the main arm is the angular velocity of the main arm relative to the tower arm; the angular speed of the tower arm is the angular speed of the tower arm relative to the horizontal plane; the angular velocity of the fly jib is the angular velocity of the fly jib relative to the main jib.
In this embodiment, the luffing mechanism of the boom system is a three-hinge-point or multi-hinge-point connecting rod type luffing mechanism, and the angular velocity of the boom and the velocity of the driving oil cylinder change in a non-linear manner. Within the precision error allowable range of the platform, the angular speed of each arm support and the speed of the driving oil cylinder have the following relationship:
according to the above formulae (2), (3) and
the following can be obtained:
wherein, { p11、p12、p13}、{p21、p22、p23And { p }31、p32、p33The structural coefficient sets of the luffing mechanisms of the main arm, the tower arm and the fly jib respectively, wherein p1i、p2i、p3iRespectively representing a first structural coefficient, a second structural coefficient and a third structural coefficient of the amplitude variation mechanism of each arm support i; and
and
the angular velocities of the main arm, the tower arm and the fly jib respectively.
In this embodiment, under the condition that 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 can be determined, so that the kinematic model determined by the above formula (4) can be determined. Then, after the angular velocity of the boom is determined by detecting the output flow of the hydraulic control valve bank in real time, the platform velocity acquisition module can determine the angular velocity of the platform through the formula (4).
In this embodiment, a model of the boom movement speed and the platform movement speed is used to describe a complex relationship between the movement speeds of different booms and the platform movement speed. The complex arm support motion caused by the complex working conditions is simplified into the change of the platform motion speed, and a foundation is provided for ensuring that the leveling control is adaptive to the complex and variable working conditions. Therefore, the problems of overshoot and oscillation easily caused by the situations of various structural forms of the arm support, uncertain operation combination, complex and variable arm support motion and the like of the leveling control can be solved.
Finally, a process of acquiring the pre-control amount of the leveling valve, which is performed by the pre-control amount acquisition module, will be described.
Since the relationship between the control signal for controlling the leveling valve of the platform and the movement speed of the platform is a non-linear relationship, the present embodiment can inversely calculate the valve control amount required to maintain the movement speed of the platform through a relationship model between the pre-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 with respect to the fly arm, that is, the angular speed of the platform). Specifically, a negative value of the movement speed of the platform (namely, the negative value is the same as the movement speed but opposite to the movement speed) is taken, a relation model between the advanced control quantity of the leveling valve and the movement speed of the platform is introduced, and the advanced control quantity acquisition module can acquire the advanced control quantity of the leveling valve. Therefore, the horizontal angle change of the platform caused by the movement of the arm support can be counteracted through the obtained preposed control quantity of the leveling valve, and therefore stable and reliable leveling control of the working platform is achieved.
In this embodiment, the specific relationship model may be a data table, the input of which is the movement speed of the platform, and the output of which is the pilot control amount of the leveling valve. For example, the data related to the relational model can be obtained through actual measurement by adopting a control variable method and a segmented calibration method. For the section with obvious nonlinearity of the leveling valve and the position with large change of the motion speed of the platform, the number of sampling points is increased, and the actual characteristic is approached as much as possible. Thus, the relational model employed in the present embodiment reflects the velocity changes caused by the non-linear factors of the leveling valve. The control instruction (namely the preposed control quantity of the leveling valve) for controlling the leveling valve can be accurately predicted according to the movement speed of the platform, so that the platform can be subjected to real-time leveling control according to the preposed control quantity of the leveling valve. Of course, the specific relationship model for the leveling valve may represent the relationship diagram shown in FIG. 5.
Of course, in another embodiment, the advanced control amount acquisition means includes: the boom speed acquisition module is used for acquiring the movement speed of the boom by acquiring the angle of the boom; the platform speed acquisition module is used for acquiring the motion speed of the platform by acquiring the angle of the platform; and the preposed control quantity acquisition module is used for acquiring the preposed control quantity of the leveling valve according to the motion speed of the platform and a relation model between the preposed control quantity of the leveling valve and the motion speed of the platform.
In one embodiment, the leveling control amount obtaining 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 preposed 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 preposed control quantity of the leveling valve and the leveling deviation, wherein the leveling deviation is the angle of the platform deviating from the horizontal plane; 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.
In one 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 pre-control quantity of the leveling valve and a preset proportion as the feedforward control quantity of the leveling valve.
In particular, the amount of pilot control P of the leveling valve can be adjusted according to the amount of pilot control P of the leveling valvelevelAnd the following formula (5) for calculating the feedforward control amount PForwad：
PForwad＝Kf*Plevel， (5)
Where Kf is a feedforward control coefficient, which is used to adjust the strength of the feedforward control (for example, it may take a value of 1).
In the embodiment, the speed control instruction is input, the movement speed of the arm support can be estimated in advance without the movement of the arm support, and therefore the leveling valve can be controlled to move along with the arm support in time; and because the estimated boom movement speed is only influenced by the valve control quantity, the fluctuation is small, and the movement trend of the boom 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 control the platform to move along with the arm support in time. The working condition self-adaptive control algorithm finely adjusts the translational motion on the basis of feedforward control, and eliminates leveling deviation caused by the temperature of a hydraulic system, the deflection of an arm support, load change and external interference.
Because the preposed control quantity of the leveling valve is calculated according to the control instruction of the boom speed, the leveling valve can be synchronously opened with a hydraulic valve of the boom, and the platform can timely move along with the boom. The nonlinear change of the speed caused by factors such as a hydraulic system, a boom structure and the like can be directly included in the preposed 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 the platform angle change caused by the boom movement speed, so that the platform angle change caused by the nonlinear factors can be effectively restrained. However, the system still has the influence of factors such as the temperature of a hydraulic system, the deflection of the arm support, the load change and the like, and the error of the leveling control cannot be ensured only through the feedforward control.
In one embodiment, the feedback control amount acquisition module for determining the feedback control amount of the leveling valve includes: determining the feedback control quantity of the leveling valve to be 0 under the condition that the prepositive control quantity of the leveling valve is 0 or the leveling deviation is smaller than the preset deviation; determining the feedback control quantity of the leveling valve according to the leveling deviation and a first PID control strategy under the condition that the pre-control quantity of the leveling valve is not 0 or the leveling deviation is greater than or equal to the preset deviation; determining the feedback control quantity of the leveling valve according to the leveling deviation and a second PID control strategy under the condition that the preposed control quantity of the leveling valve is not 0 and the duration time exceeds the preset time or the leveling deviation is greater than or equal to the preset deviation and the duration time exceeds the preset time; or 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 preposed control quantity 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 stages: a waiting phase, a starting phase, a regulating phase and a stopping phase.
Feedback control quantity f (P) of leveling valveForwardAnd e) denotes a control amount determined by a feedforward control amount (which depends on a pilot control amount of the leveling valve) and the leveling deviation. Specifically, the stage of the leveling working condition can be accurately evaluated according to the change of the feedforward control quantity (which depends on the preposed control quantity of the leveling valve) of the leveling valve; and in each stage, e is taken as the input of the corresponding PID control, and the feedback control quantity is taken as the output of the corresponding PID control (the specific parameters in the PID control strategy adopted in each stage are different). That is, f (P)ForwardAnd e) is a piecewise function.
A waiting stage: when the pre-control quantity 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 the stageForwardAnd e) is 0, and cyclically detects the change of the pre-control amount of the leveling valve and the leveling deviation.
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 started. At this stage, the leveling deviation is taken as input, and f (P) is output according to a first PID control strategyForward,e)。
And the main task of the starting stage is to quickly open the leveling valve and track the movement of the arm support in time. Because the leveling valve has time difference from the sending of the control command to the leveling action and is influenced by the valve control quantity, the control strategy in the starting stage is as follows: the leveling is started at the fastest speed, but the sudden change of the platform angle is not caused. The length of the activation phase is adjusted by a parameter, the activation time, which can be determined (e.g., can be a reasonable constant) based on the characteristics of the leveling valve.
For the first PID control strategy, it is desirable that the hydraulic valve can be opened quickly at this stage to track the boom movement in time, so that the P parameter is set relatively large. Since 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: entering the regulation phase is indicated when the pilot control quantity of the leveling valve is not equal to 0 and the maintenance time exceeds the preset start time, or when the leveling deviation is greater than or equal to the preset deviation and the maintenance time exceeds the preset start time (i.e. the start phase is ended). At this stage, the leveling deviation is taken as input, and f (P) is output according to a second PID control strategyForward,e)。
For the second PID control strategy, it is desirable to have a smooth leveling action at this stage to improve the comfort of the operator, so the P parameter is set 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 working platform level.
A stopping stage: when the pilot control quantity of the leveling valve is again equal to 0 or the leveling deviation is again less than the preset deviation, it is indicated that the stop phase is entered. The stopping stage mainly aims to eliminate the integral accumulated value generated by the PID control and prevent the working platform from oscillating and adjusting after the movement of the arm support stops. At this stage, the leveling deviation is taken as input, and f (P) is output according to a third PID control strategy (wherein, the integral accumulation value can be set to 0)Forward，e)。
For the third PID control strategy, since the hydraulic valve has hysteresis, this phase will take a different parameter than the start phase, generally the P parameter is smaller than the start phase and larger than the regulation phase, and the I parameter takes zero. In addition, to prevent integration saturation, an integration zero out strategy is taken at the end of this phase.
And the first PID control strategy, the second PID control strategy and the third PID control strategy relate to different control parameters. The specific PID control process can be performed according to the prior art, and is not described in detail herein.
On the basis that the feedforward control ensures the timely response of the leveling control, the staged control of the feedback control quantity can eliminate the leveling error caused by factors such as the temperature of a hydraulic system, the deflection of an arm support, the load change, the external interference and the like, can also avoid the platform angle oscillation caused by the conventional PID control, and greatly improves the control precision.
In one embodiment, the amount P of feedforward control based on the leveling valveForwardFeedback control quantity f (P) with the leveling valveForwardE), the leveling control amount acquisition module may determine a control amount P of the leveling valve expressed by the following equationadapt，
Padapt＝PForward+f(PForward，e)， (6)
Accordingly, the control device 30 can control the control amount P of the leveling valve according to the above determinationadaptAnd controlling the leveling valve to operate.
In the existing leveling control process with hysteresis, the leveling valve needs to frequently act (open/close) because the movement speed of the arm support is in nonlinear change, so that the leveling control experience is poor. On the basis that feedforward control ensures that the platform actively moves along 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 leveling process will now 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.
And S301, acquiring the movement speed of the arm support according to the control command of the hydraulic valve and the first relation model.
And the first relation model is a relation model between the control quantity of the hydraulic valve and the movement speed of the arm support.
And step S302, acquiring the motion speed of the platform according to the motion speed of the arm support and the kinematics model.
The kinematic model is a kinematic model between the movement speed of the arm support and the movement speed of the platform.
And step S303, acquiring the preposed control quantity of the leveling valve according to the motion speed of the platform and the second relation model.
Wherein the second relational model is a relational model between a pre-control amount of a leveling valve for controlling the platform and a movement speed of the platform.
And step S304, acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the preposed 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 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 velocity of the platform refers to the angular change rate of the platform caused by the leveling action of the leveling mechanism, so that the motion velocity of the platform can be replaced with the leveling motion velocity of the platform; the "angular velocity of the platform" may be interchanged with the "leveling angular velocity of the platform".
In summary, the invention creatively obtains the preposed 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, acquiring the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the prepositive 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 translation adjusting action on the basis of feed forward control so as to adapt to the working condition change, thereby eliminating the leveling deviation caused by the temperature of a hydraulic system, the deflection of the arm support, the load change and the external interference.
The embodiment of the invention also provides a leveling method. The leveling method may include: acquiring a preposed 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 preposed 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 controlling the leveling valve according to the control quantity of the leveling valve.
For details and benefits of the leveling method provided by the embodiment of the present invention, reference may be made to the above description of the leveling system, and further description is omitted here.
The embodiment of the invention also provides engineering machinery, and the engineering machinery comprises the leveling system. Wherein, the engineering machinery can be high-altitude operation equipment.
For details and advantages of the engineering machine provided by the embodiment of the present invention, reference may be made to the above description of the leveling system, and further description is omitted here.
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, 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 technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (10)
1. A leveling system, comprising:
the device comprises a preposed control quantity acquisition device, a leveling valve control device and a control device, wherein the preposed control quantity acquisition device is used for acquiring a preposed control quantity of the leveling valve used for controlling the platform according to the movement speed of the arm support and the movement speed of the platform;
the leveling control quantity obtaining device is used for obtaining the control quantity of the leveling valve according to a working condition self-adaptive control algorithm and the preposed 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
and the control device is used for controlling the leveling valve according to the control quantity of the leveling valve.
2. The leveling system according to claim 1, wherein the advanced control amount obtaining means includes:
the boom speed acquisition module is used for acquiring the movement speed of the boom according to the control quantity of a hydraulic valve for controlling the movement of the boom and a relation model between the control quantity of the hydraulic valve and the movement speed of the boom;
the platform speed acquisition module is used for 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 the preposed control quantity acquisition module is used for acquiring the preposed control quantity of the leveling valve according to the motion speed of the platform and a relation model between the preposed control quantity of the leveling valve and the motion speed of the platform.
3. The leveling system of claim 1, wherein the relationship model between the control quantity of the hydraulic valve and the movement speed of the boom comprises: a non-linear model between a control quantity of the hydraulic valve and an angular velocity of the boom.
4. 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 current on-off time or a duty cycle of voltage on-off time.
5. The leveling system of claim 1, wherein the kinematic model between the boom movement speed and the platform movement speed comprises: a kinematic model between the angular velocity of the boom and the angular velocity of the platform.
6. The leveling system according to claim 1, wherein the leveling control amount obtaining means includes:
the feedforward control quantity acquisition module is used for determining the feedforward control quantity of the leveling valve according to the preposed 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 preposed control quantity of the leveling valve and the leveling deviation, wherein the leveling deviation is the angle of the platform deviating from the 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.
7. The leveling system of claim 6, wherein the feed-forward control amount obtaining module for determining the feed-forward control amount of the leveling valve comprises:
and determining the product of the pre-control quantity of the leveling valve and a preset proportion as the feedforward control quantity of the leveling valve.
8. The leveling system of claim 6, wherein the feedback control amount acquisition module to determine the feedback control amount of the leveling valve comprises:
determining the feedback control quantity of the leveling valve to be 0 under the condition that the prepositive control quantity of the leveling valve is 0 or the leveling deviation is smaller than the preset deviation;
determining the feedback control quantity of the leveling valve according to the leveling deviation and a first PID control strategy under the condition that the pre-control quantity of the leveling valve is not 0 or the leveling deviation is greater than or equal to the preset deviation;
determining the feedback control quantity of the leveling valve according to the leveling deviation and a second PID control strategy under the condition that the preposed control quantity of the leveling valve is not 0 and the duration time exceeds the preset time or the leveling deviation is greater than or equal to the preset deviation and the duration time exceeds the preset time; or
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 pre-control quantity of the leveling valve becomes 0 or the leveling deviation becomes smaller than the preset deviation.
9. A leveling method, characterized in that the leveling method comprises:
acquiring a preposed 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 preposed 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
and controlling the leveling valve according to the control quantity of the leveling valve.
10. A working machine, characterized in that the working machine comprises a levelling system according to any one of claims 1-8.
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