CN112727858A - Point position control method, hydraulic control system and engineering vehicle - Google Patents
Point position control method, hydraulic control system and engineering vehicle Download PDFInfo
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- CN112727858A CN112727858A CN202110057571.9A CN202110057571A CN112727858A CN 112727858 A CN112727858 A CN 112727858A CN 202110057571 A CN202110057571 A CN 202110057571A CN 112727858 A CN112727858 A CN 112727858A
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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
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/08—Servomotor systems incorporating electrically operated control means
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/665—Methods of control using electronic components
- F15B2211/6656—Closed loop control, i.e. control using feedback
Abstract
The application relates to a point location control method, a hydraulic control system and an engineering vehicle. The method comprises the following steps: judging whether the current input into the electro-hydraulic proportional valve is smaller than a preset sliding current or not before the hydraulic driving device moves to a sliding area in a deceleration mode; if so, switching the current input into the electro-hydraulic proportional valve to be a preset slide current; when the hydraulic driving device moves to a sliding area, judging whether the current input into the electro-hydraulic proportional valve is larger than or equal to a preset sliding current; if so, switching the current input into the electro-hydraulic proportional valve to be a preset slide current; and after the current input into the electro-hydraulic proportional valve is switched to be the preset slide current, continuously controlling the current input into the electro-hydraulic proportional valve to be the preset slide current until the hydraulic driving device moves to the target position. By adopting the method, the hydraulic driving device can quickly, accurately and stably reach the target position.
Description
Technical Field
The application relates to the technical field of hydraulic control, in particular to a point position control method, a hydraulic control system and an engineering vehicle.
Background
In the hydraulic control field, it is often necessary to perform accurate position control on hydraulic driving devices such as a hydraulic oil cylinder and a hydraulic motor, for example, the hydraulic oil cylinder is controlled to accurately extend from any point to a certain point position, and the hydraulic motor is accurately rotated from any angle to a certain angle position. The accurate point position control of a hydraulic oil cylinder or a hydraulic motor is generally realized through an electro-hydraulic proportional valve. The electro-hydraulic proportional valve is a component in which a proportional electromagnet in the valve generates corresponding action according to an input voltage signal, so that a valve core of a working valve generates displacement, the size of a valve port is changed, and pressure and flow output in proportion to the input voltage is completed. The electro-hydraulic proportional valve can continuously control parameters such as pressure, flow and the like of hydraulic oil according to an input electric signal and enables the parameters to be changed approximately in proportion to the input electric signal, so that fine motion control of a hydraulic oil cylinder and a hydraulic motor can be realized through closed-loop control, and accurate position positioning is realized. However, the valve core of the electro-hydraulic proportional valve has a neutral dead zone, the valve core adopts open-loop control to cause that the opening of the proportional valve cannot be in an ideal linear relation with an electric signal, the reciprocating motion of the valve core has large hysteresis characteristics and the like, so that the electro-hydraulic proportional valve is not as good as an electro-hydraulic servo valve in accurate control, and has a large difference from the electro-hydraulic servo valve in closed-loop control performance. The electro-hydraulic proportional valve is low in price and high in pollution resistance, so that the electro-hydraulic proportional valve is widely applied to the market, and particularly widely applied to the field of engineering machinery. The electro-hydraulic proportional valve is used for controlling a walking motor and a rotary motor of an excavator and a rotary drilling rig, controlling the rotation of a rotary table of an automobile crane and a rotary table of a concrete pump truck and the like.
The electro-hydraulic proportional valve is widely used in these machines due to the aspects of use cost, strong anti-pollution capability, operation resistance and the like, but the electro-hydraulic proportional valve increases the difficulty for the closed-loop control of the hydraulic cylinder and the hydraulic motor. The following description will be given taking the control of the rotational positioning of the rotary drilling rig as an example. A rotary drilling rig is a quick hole forming construction machine. The rotary bucket is driven by the drill rod to rotate to cut soil, and then the rotary bucket is lifted to the outside of the hole to unload the soil, and the periodic cycle operation is carried out. The rotary drilling rig is generally used for construction of various cast-in-place piles, secant piles and continuous walls. When the rotary drilling rig drills a hole, cut soil can be extracted to the ground from the deep hole, then the body of the rotary drilling rig is rotated, waste soil is dumped on one side, then the body is rotated, and a drill rod and a drilling tool are aligned with the hole position again to continue drilling downwards. These operations are currently performed manually by an operator. At present, electro-hydraulic proportional control is adopted at the horizontal rotation position of a vehicle body of a rotary drilling rig to realize automatic rotation and hole position alignment operation, so that the working intensity of operators is reduced, and the usability of the rotary drilling rig is improved. To realize the automatic rotation hole aligning function, a sensor (a rotation angle sensor or a rotation position sensor) for detecting a rotation angle, an electro-hydraulic proportional valve (or an electro-hydraulic proportional pressure reducing valve) and a rotation positioning start button are generally required to be arranged on the rotary drilling rig. The specific working mode is that the angle position (drilling angle position) of the vehicle body is recorded during drilling, after an operator finishes the actions of lifting soil and unloading soil and presses a rotary positioning start button, the controller can drive an electro-hydraulic proportional device (an electro-hydraulic proportional valve or an electro-hydraulic proportional pressure reducing valve) to drive a rotary motor to act, and the vehicle body is controlled to rapidly rotate to the drilling position according to a real-time angle position signal fed back by the rotation angle sensor. This eliminates the need for manual labor to align the holes. Such automatic hole aligning systems need to meet both requirements of rapidity and accuracy. Rapidity means that the turn-around and hole-aligning speed cannot be slower than an excellent manipulator. The accuracy means that the hole aligning error must be within a specified range, and the precision of the hole is generally within +/-0.1 degrees.
As the electro-hydraulic proportional device has a plurality of problems of neutral dead zone, hysteresis, nonlinearity and the like, and the characteristics are also influenced by factors such as the viscosity of hydraulic oil, the temperature of the hydraulic oil and the like, the quick and accurate control is difficult to realize all the time in the long life cycle of equipment.
Disclosure of Invention
In view of the above, it is necessary to provide a point position control method, a hydraulic control system, and an engineering vehicle that improve the accuracy of a hydraulic drive apparatus.
A point location control method, the method comprising:
judging whether the current input into the electro-hydraulic proportional valve is smaller than a preset sliding current or not before the hydraulic driving device moves to a sliding area in a deceleration mode; the sliding area is in a deceleration stage in the moving process of the hydraulic driving device, and the moving area of the hydraulic driving device, which is less than a preset value from the target position, is used as the sliding area;
if the current input into the electro-hydraulic proportional valve is smaller than the preset sliding current, switching the current input into the electro-hydraulic proportional valve to be the preset sliding current;
when the hydraulic driving device moves to a sliding area, judging whether the current input into the electro-hydraulic proportional valve is larger than or equal to a preset sliding current;
if the current input into the electro-hydraulic proportional valve is larger than or equal to the preset sliding current, switching the current input into the electro-hydraulic proportional valve to be the preset sliding current;
and after the current input into the electro-hydraulic proportional valve is switched to be the preset slide current, continuously controlling the current input into the electro-hydraulic proportional valve to be the preset slide current until the hydraulic driving device moves to the target position.
In one embodiment, the point location control method further includes: judging whether the output current of the controller is greater than a preset sliding current or not when the hydraulic driving device moves to a sliding area; if the output current is larger than the preset slide current, reducing the preset dead zone current by a first value; the preset dead zone current is set according to the critical current of the hydraulic driving device.
In one embodiment, the point location control method further includes: judging whether the output current of the controller is smaller than a preset sliding current or not in the deceleration stage of the movement of the hydraulic driving device; and if the output current is smaller than the preset slide current, increasing the preset dead zone current by a first value.
In one embodiment, after continuously controlling the current input to the electro-hydraulic proportional valve to be a preset coasting current until the hydraulic drive device moves to the target position, the method comprises the following steps:
when the stop position of the hydraulic driving device crosses the target position in the forward moving direction, reducing the preset sliding current by a second value, and adopting a reverse sliding current to perform reverse sliding;
and when the hydraulic driving device slides reversely to cross the target position under the action of the reverse sliding current, reducing the preset reverse sliding current by a second value.
In one embodiment, after continuously controlling the current input to the electro-hydraulic proportional valve to be a preset coasting current until the hydraulic drive device moves to the target position, the method comprises the following steps: when the stop position of the hydraulic driving device crosses a target position in the forward moving direction, switching the current input into the electro-hydraulic proportional valve into a preset reverse sliding current; and continuously controlling the current input into the electro-hydraulic proportional valve to be the preset reverse sliding current until the hydraulic driving device moves to the target position.
In one embodiment, the continuously controlling the current input to the electro-hydraulic proportional valve to be a preset slide current until the hydraulic driving device moves to the target position comprises the following steps: continuously controlling the magnitude of current input into the electro-hydraulic proportional valve to be preset sliding current, and when the hydraulic driving device stops moving before reaching a target position, controlling the magnitude of the current input into the electro-hydraulic proportional valve to be increased sliding current after the current input into the electro-hydraulic proportional valve is reduced; the increased sliding current is obtained by increasing a second value according to a preset sliding current; and continuously controlling the magnitude of the current input into the electro-hydraulic proportional valve to be the increased coasting current until the hydraulic driving device moves to the target position.
In one embodiment, the magnitude of the current continuously input to the electro-hydraulic proportional valve is a preset coasting current, and when the hydraulic driving device stops moving before reaching the target position, the magnitude of the current input to the electro-hydraulic proportional valve is controlled to be an increased coasting current after the current input to the electro-hydraulic proportional valve is reduced, including: and continuously controlling the magnitude of the current input into the electro-hydraulic proportional valve to be a preset sliding current, and when the hydraulic driving device stops moving before reaching the target position, controlling the magnitude of the current input into the electro-hydraulic proportional valve to be an increased sliding current after the current input into the electro-hydraulic proportional valve is reduced to zero.
In one embodiment, the hydraulic drive device moving process comprises an acceleration phase and a deceleration phase; the hydraulic driving device is controlled in an open loop mode in an acceleration stage, and controlled in a closed loop mode in a deceleration stage; or the moving process of the hydraulic driving device comprises an acceleration stage, a constant speed stage and a deceleration stage; the hydraulic driving device is controlled in an open loop mode in an acceleration stage and a constant speed stage, and is controlled in a closed loop mode in a deceleration stage.
A hydraulic control system comprises a controller, a hydraulic proportional valve, a hydraulic driving device and a position sensor, wherein the hydraulic driving device comprises a hydraulic control valve and a hydraulic control valve; the hydraulic driving device is a hydraulic motor or a hydraulic oil cylinder.
A working vehicle comprises the hydraulic control system in the embodiment.
According to the point position control method, the hydraulic control system and the engineering vehicle, through the arrangement of the sliding area, when the hydraulic driving device reaches the sliding area, the valve core of the hydraulic driving device is controlled to be opened according to the sliding current, even if the dead zone current changes, the hydraulic driving device can be controlled to reach the target position, overshoot and undershoot caused by the fact that a PID control mode is used when the hydraulic driving device is close to the target position are avoided, and the hydraulic driving device can quickly, accurately and stably reach the target position.
Drawings
FIG. 1 is a schematic flow chart of a point location control method according to an embodiment;
FIG. 2 is a schematic diagram of a current-spool curve in one embodiment;
FIG. 3 is a graphical illustration of current-velocity-displacement versus time in one embodiment;
FIG. 4 is a schematic diagram of a control system in one embodiment;
FIG. 5 is a schematic diagram of a control method of the control system in one embodiment;
FIG. 6 is a schematic diagram of a hydraulic system regulation curve in one embodiment;
FIG. 7 is a diagram of a dead band adjustment curve in one embodiment;
FIG. 8 is a schematic diagram of a dead band adjustment curve in another embodiment;
FIG. 9 is a graphical illustration of an embodiment increase in coasting current;
FIG. 10 is a graph of displacement and input circuit curves for an acceleration phase, a uniform velocity phase, and a deceleration phase, under an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Fig. 2 is a schematic current-spool curve. Fig. 2 illustrates the general characteristics of an electro-hydraulic proportional valve. The I _ dead current is called dead zone current and is the minimum current value for opening the valve core of the electro-hydraulic proportional valve. The I _ max is called the maximum current and is the current value of the valve core of the electro-hydraulic proportional valve which is 100% open. Between the dead zone current I _ dead and the maximum current I _ max, the valve core opening amount and the current increase amount are approximately in a proportional relationship.
Fig. 3 shows a graph of current I, velocity V, displacement S over time. In fig. 3, there are 3 curves in total, which are a current-time curve, a velocity-time curve, and a displacement-time curve, respectively. The current I in FIG. 3 is the current (or voltage) driving the electro-hydraulic proportional valve or other electro-hydraulic proportional device; the speed V is the moving speed of a hydraulic oil cylinder or the rotating angular speed of a hydraulic motor; the displacement S is the linear displacement of a hydraulic ram or the angular displacement of a hydraulic motor. the first section of curve (i) is arranged between t0 and t1, the second section of curve (ii) is arranged between t1 and t2, and the third section of curve (iii) is arranged between t2 and t 3.
Fig. 4 shows a schematic configuration of the control system. In order to allow a hydraulic cylinder or a hydraulic motor (collectively referred to as a hydraulic drive) to move from a start position S _ src to a target position S _ dst quickly and accurately and stop, the required overall control system is shown in fig. 4 and comprises the following: the controller mainly collects position data S _ src of the hydraulic driving device fed back by the position sensor, and outputs a certain current I _ out to an electro-hydraulic proportional device (an electro-hydraulic proportional valve or an electro-hydraulic proportional pressure reducing valve) by using corresponding operation logic and a control method according to a given target position S _ dst, the electro-hydraulic proportional device then changes the flow (Q) of hydraulic oil flowing into the hydraulic device (a hydraulic oil cylinder or a hydraulic motor), so that the hydraulic device is driven to move towards the target position S _ dst, and the position sensor collects the current position S _ cur of the hydraulic driving device in real time and feeds the current position S _ cur back to the controller to complete the next control operation.
Fig. 5 shows a control method schematic of the control system. Here, the control target is a hydraulic drive device, and in fig. 5, the target position S _ dst is subtracted from the actual position S _ cur to obtain a position deviation S _ dev. The control method is that the output current I _ out is adjusted through the size of the position deviation S _ dev, the current position S _ cur of the control object is driven to change, and finally the position deviation S _ dev is eliminated, so that the position deviation S _ dev becomes zero, and the purpose that the current position S _ cur is equal to the target position is achieved, and tracking is completed. And I _ out is the current output to the electro-hydraulic proportional device. The current I _ out is formed by adding the regulated current I _ adj output by the control method and the dead-zone current I _ dead, that is, I _ out is I _ adj + I _ dead. Without considering the dead zone current, it is believed that the regulating current I _ adj may correspond to the opening of the valve port from 0. When the control object reaches the target position, the actual situation is that the current position S _ cur and the target position S _ dst of the control object cannot be completely the same, the position deviation S _ dev of the control object and the target position S _ dst is generally controlled within a range, and the rotation angle position error S _ dev is generally controlled within ± 0.1 ° taking the rotary drilling rig as an example.
When the actual position of the controlled object is greatly deviated from the target position, the driving control is realized by 3 sections of curves, and the control method of the hydraulic control system is as follows:
the first section of curve is: the control current (I _ out) is gradually increased, the valve core opening of the proportional valve is gradually increased, the hydraulic oil flow (Q) is gradually increased, the speed (v _ cur) of a control object is gradually increased, and the current position (S _ cur) also gradually approaches the target position (S _ dst).
Second curve 2: the current (I _ out) reaches the maximum (I _ max), the spool opening of the proportional valve reaches 100%, and the hydraulic oil flow rate (Q) reaches the maximum, so that the speed (v _ cur) of the control target is increased to the maximum v _ max, and the maximum speed is kept to continue approaching the target position.
Third section curve c: the current (I _ out) is gradually reduced, the valve core opening is reduced, the hydraulic oil flow (Q) and the speed v _ cur are also gradually reduced, and the control object continuously approaches to the target position from the current position; when the control object reaches the vicinity of the target position, the current (I _ out) is close to or lower than the dead zone current I _ dead, the valve port is completely closed, the speed becomes zero, and the control is finished.
Wherein, when the current (I _ out) is below the dead zone current I _ dead, the valve port of the hydraulic driving device is basically in a closed state, therefore, in order to make the hydraulic driving device move, the current must be higher than the dead zone current I _ dead, which is the point at which the valve port is just opened, and the problem is that the dead zone current I _ dead is affected by various factors such as hydraulic oil, a valve core and the like, the dead zone current I _ dead is not a layer and is not constant, the dead zone current I _ dead changes, which leads to adopting a regulation method similar to the PID of the hydraulic control system, when the hydraulic driving device is controlled to the target position, overshoot (curve (r) in fig. 6) is often generated, the overshoot means that the rotary drilling rig rotates in the forward direction and then rotates in the reverse direction, the control time is increased by the forward rotation and the reverse rotation for multiple times, if an undershoot occurs (curve (c) of fig. 5) the regulation is also slowed down, resulting in an increased control time. The hydraulic system is a very complex strongly nonlinear large hysteresis object system that is difficult to analyze by mathematical modeling.
The current I _ out output to the electrohydraulic device is I _ adj + I _ dead as mentioned above. Ideally, when I _ adj is equal to 0, I _ out is equal to I _ dead, and the hydraulic drive device just stops moving. However, in fact, under the influence of various factors of the hydraulic system, when I _ adj is equal to 0, I _ out is equal to I _ dead, but I _ dead may still allow the system to continue to move, or the system may stop moving when I _ adj has not reached zero. That is, the dead zone current I _ dead does not sufficiently represent the state in which the hydraulic device is stopped, thereby causing uncertainty in the control of the hydraulic drive device. To address this uncertainty, in one embodiment, as shown in FIG. 1, a point location control method is provided, the method comprising:
s110, judging whether the current input into the electro-hydraulic proportional valve is smaller than a preset sliding current or not before the hydraulic driving device moves to a sliding area in a deceleration mode; and the sliding area is in a deceleration stage in the moving process of the hydraulic driving device, and the moving area of the hydraulic driving device, which is less than a preset value from the target position, is used as the sliding area.
The preset coasting current is a current determined according to a dead zone current I _ dead, the dead zone current I _ dead is a critical current for the control system in the hydraulic system to operate, the preset coasting current is slightly larger than the dead zone current I _ dead, and is a current for ensuring that the hydraulic system can normally move, for example, the initial value may be set to be 5% larger than the dead zone current I _ dead. In the embodiment of the present application, the preset coasting current is mentioned, and may be automatically increased or decreased (self-learned) according to the situation, so that the initial value of the preset coasting current may be preliminarily set at a value slightly larger than the dead zone current I _ dead.
The preset value can be set according to requirements, for example, when the hydraulic motor is applied, the preset value can be set to be 2 degrees, and when the hydraulic motor is applied, the preset value can be set to be 2 cm. Referring to fig. 3, the sliding area is located on the third section of the curve (c). As shown in fig. 7 and 8, a region from the target position S _ dst less than a certain value (glide distance) is referred to as a glide region, that is, a region from S _ slide to the target position S _ dst in the drawing. The sliding area can be a rotation angle area of a hydraulic motor or a telescopic moving area of a hydraulic oil cylinder. In the rotary positioning control of the rotary drilling rig, the sliding area can be set to be an angle of 2 degrees away from a target angle, namely the preset value is 2 degrees; of course, the size of the sliding area can be determined experimentally according to different application scenarios. Here, the target position S _ dst is one point.
And S120, if the current input into the electro-hydraulic proportional valve is smaller than the preset slide current, switching the current input into the electro-hydraulic proportional valve to be the preset slide current.
And S130, when the hydraulic driving device moves to a sliding area, judging whether the current input into the electro-hydraulic proportional valve is larger than or equal to a preset sliding current.
And S140, if the current input into the electro-hydraulic proportional valve is greater than or equal to the preset slide current, switching the current input into the electro-hydraulic proportional valve to be the preset slide current.
And S150, after the current input into the electro-hydraulic proportional valve is switched to be the preset slide current, continuously controlling the current input into the electro-hydraulic proportional valve to be the preset slide current until the hydraulic driving device moves to the target position.
The target position is a region, and when the hydraulic drive device is controlled, a position deviation exists between a position where the hydraulic drive device is allowed to finally reach and a target position S _ dst point, for example, the position deviation allowed by the rotary drilling rig is ± 0.1 °.
According to the point position control method, through the arrangement of the sliding area, when the hydraulic driving device reaches the sliding area, the valve core of the hydraulic driving device is controlled to be opened according to the sliding current, even if the dead zone current changes, the hydraulic driving device can be controlled to reach the target position, overshoot and undershoot caused by the fact that a PID control mode is used when the dead zone current is close to the target position are avoided, and the hydraulic driving device can quickly, accurately and stably reach the target position.
In one embodiment, the point location control method further includes: judging whether the output current of the controller is greater than a preset sliding current or not when the hydraulic driving device moves to a sliding area; if the output current is larger than the preset slide current, reducing the preset dead zone current by a first value; the preset dead zone current is set according to the critical current of the hydraulic driving device.
The first value may be determined as desired, for example, the first value may be 1mA, 2mA, or 100 mA. As shown in fig. 7, when the output current I _ out enters the coasting area, if I _ out > I _ slide (coasting current), the operation is switched to the preset coasting current operation until the hydraulic drive reaches the target position, and the dead zone current I _ dead is decreased by a current value (first value) so that the output current I _ out is closer to the preset coasting current I _ slide when the dead zone current I _ dead is adjusted to enter the coasting area next time. In this embodiment, the adjustment of the dead-band current is performed once during the movement of the primary hydraulic drive device from the start position to the target position.
In one embodiment, the point location control method further includes: judging whether the output current of the controller is smaller than a preset sliding current or not in the deceleration stage of the movement of the hydraulic driving device; and if the output current is smaller than the preset slide current, increasing the preset dead zone current by a first value.
The first value may be determined as desired, for example, the first value may be 1mA, 2mA, or 100 mA. As shown in fig. 8, the output current I _ out is already reduced to be below the preset coasting current I _ slide in advance when the output current I _ out does not enter the coasting area, the output current is directly switched to be the preset coasting current for operation until the hydraulic drive device reaches the target position, and the dead zone current I _ dead is adjusted upward by a current value (a first value), so that the output current I _ out is closer to the coasting current I _ slide when the dead zone current I _ dead is adjusted to enter the coasting area next time. In this embodiment, the adjustment of the dead-band current is performed once during the movement of the primary hydraulic drive device from the start position to the target position.
In one embodiment, after continuously controlling the current input to the electro-hydraulic proportional valve to be a preset coasting current until the hydraulic drive device moves to the target position, the method comprises the following steps: when the stop position of the hydraulic driving device crosses the target position in the forward moving direction, reducing the preset sliding current by a second value, and adopting a reverse sliding current to perform reverse sliding; and when the hydraulic driving device slides reversely to cross the target position under the action of the reverse sliding current, reducing the preset reverse sliding current by a second value.
The preset reverse sliding current may be the same as or different from the preset sliding current, the preset reverse sliding current controls the hydraulic driving device to move in a reverse direction, and an initial value of the preset reverse sliding current may be a value slightly larger than the dead zone current I _ dead, for example, the initial value may be set to be 5% larger than the dead zone current I _ dead. The second value may be the same as or different from the first value, and may be set as desired, for example, the second value may be 1mA, 2mA, or 100 mA.
In the embodiment, the target position is a point, and when the hydraulic driving device moves beyond the target position under the inertia effect, the preset sliding current is reduced by a second value in order to accurately control the hydraulic driving device next time; or when the hydraulic driving device moves beyond the target position under the action of inertia during reverse movement, reducing the preset reverse sliding current by a second value in order to accurately control the hydraulic driving device next time.
In one embodiment, after continuously controlling the current input to the electro-hydraulic proportional valve to be a preset coasting current until the hydraulic drive device moves to the target position, the method comprises the following steps: when the stop position of the hydraulic driving device crosses a target position in the forward moving direction, switching the current input into the electro-hydraulic proportional valve into a preset reverse sliding current; and continuously controlling the current input into the electro-hydraulic proportional valve to be the preset reverse sliding current until the hydraulic driving device moves to the target position.
In the embodiment, the hydraulic driving device moves reversely to the target position by switching the current input into the electro-hydraulic proportional valve to the preset reverse sliding current.
In one embodiment, the continuously controlling the current input to the electro-hydraulic proportional valve to be a preset slide current until the hydraulic driving device moves to the target position comprises the following steps: continuously controlling the magnitude of current input into the electro-hydraulic proportional valve to be preset sliding current, and when the hydraulic driving device stops moving before reaching a target position, controlling the magnitude of the current input into the electro-hydraulic proportional valve to be increased sliding current after the current input into the electro-hydraulic proportional valve is reduced; the increased sliding current is obtained by increasing a second value according to a preset sliding current; and continuously controlling the magnitude of the current input into the electro-hydraulic proportional valve to be the increased coasting current until the hydraulic driving device moves to the target position.
When the hydraulic drive device is adjusted near a target position, if the preset slide current is too low, the hydraulic drive device still cannot be actuated due to the application of the preset slide current, at the moment, if the preset slide current is simply increased as shown in fig. 9A, the spool may not be actuated due to the problems of clamping stagnation of the spool and the like in fig. 9A, so that the preset slide current needs to be increased to a very high value to actuate the spool, the slide current is adjusted too much, and more serious motion overshoot is caused.
In one embodiment, the magnitude of the current continuously input to the electro-hydraulic proportional valve is a preset coasting current, and when the hydraulic driving device stops moving before reaching the target position, the magnitude of the current input to the electro-hydraulic proportional valve is controlled to be an increased coasting current after the current input to the electro-hydraulic proportional valve is reduced, including: and continuously controlling the magnitude of the current input into the electro-hydraulic proportional valve to be a preset sliding current, and when the hydraulic driving device stops moving before reaching the target position, controlling the magnitude of the current input into the electro-hydraulic proportional valve to be an increased sliding current after the current input into the electro-hydraulic proportional valve is reduced to zero.
In this embodiment, the current is increased as shown in fig. 9B, after the preset coasting current is increased, if the hydraulic drive device does not operate, the output current is again zero, and then a next larger coasting current is output from zero, such a process will cause a valve element of the hydraulic drive device to generate a larger operation, thereby avoiding the problems that the hydraulic drive device does not operate all the time due to the valve element being stuck, and the hydraulic drive device overshoots due to an excessively large final coasting current adjustment amount.
After the current input into the electro-hydraulic proportional valve is controlled to be zero, the current input into the electro-hydraulic proportional valve is controlled to be increased sliding current, the hydraulic driving device still does not act, after the current input into the electro-hydraulic proportional valve needs to be controlled to be zero again, current larger than the previous increased sliding current is input into the electro-hydraulic proportional valve, and the operation is repeated until the hydraulic driving device acts.
In one embodiment, the hydraulic drive device moving process comprises an acceleration phase and a deceleration phase; the hydraulic driving device is controlled in an open loop mode in an acceleration stage, and controlled in a closed loop mode in a deceleration stage; or the moving process of the hydraulic driving device comprises an acceleration stage, a constant speed stage and a deceleration stage; the hydraulic driving device is controlled in an open loop mode in an acceleration stage and a constant speed stage, and is controlled in a closed loop mode in a deceleration stage.
The moving process of the hydraulic driving device may only include an acceleration stage and a deceleration stage, and no constant speed stage exists, at this time, open-loop control is adopted for the hydraulic driving device in the acceleration stage, and closed-loop control is adopted for the hydraulic driving device in the deceleration stage.
The moving process of the hydraulic driving device may include an acceleration stage, a constant speed stage, and a deceleration stage, for example, as shown in fig. 10, the moving process of the hydraulic driving device includes an acceleration stage (i), a constant speed stage (ii), and a deceleration stage (iii); the hydraulic driving device is controlled in an open loop mode in an acceleration stage and a constant speed stage, and is controlled in a closed loop mode in a deceleration stage.
The hydraulic driving device moves from an initial position S _ src to a target position S _ dst, as shown by a curve in FIG. 10, the speed v and the current I input to the spool of the proportional valve of the hydraulic driving device are increased in an acceleration stage, the speed v and the current I input to the spool of the proportional valve of the hydraulic driving device are kept unchanged in a uniform speed stage, and the speed v and the current I input to the spool of the proportional valve of the hydraulic driving device are decreased in a deceleration stage. An acceleration stage, namely, accelerating by adopting a certain slope curve, and performing open-loop control on the acceleration; the closed-loop control is preferably open-loop control because the intervention of the feedback quantity easily causes the reduction of the hydraulic motion fluency, and the open-loop control has the characteristics of high speed and stable valve core action. And in the uniform speed stage II, open-loop control is still adopted, so that the stability of the opening of the valve core and the stability in operation are ensured, and closed-loop regulation is avoided. And a deceleration stage III, namely judging a deceleration time point according to a preset deceleration curve at all times in the moving process of the hydraulic driving device in the acceleration stage and the constant speed stage II, and if the deceleration time point is reached, starting to decelerate and stop according to the curve in the deceleration stage III.
It should be understood that, although the steps in the flowchart of fig. 1 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 1 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed in turn or alternately with other steps or at least a portion of the other steps or stages.
In one embodiment, there is provided a point location control apparatus including: first electric current judgement module, first circuit switching module, second electric current judgement module, second circuit switching module and removal control module, wherein:
the first current judgment module is used for judging whether the current input into the electro-hydraulic proportional valve is smaller than the preset sliding current or not before the hydraulic driving device moves to the sliding area in a deceleration mode; the sliding area is in a deceleration stage in the moving process of the hydraulic driving device, and the moving area of the hydraulic driving device, which is less than a preset value from the target position, is used as the sliding area;
the first circuit switching module is used for switching the current input into the electro-hydraulic proportional valve into the preset slide current if the current input into the electro-hydraulic proportional valve is smaller than the preset slide current;
the second current judgment module is used for judging whether the current input into the electro-hydraulic proportional valve is larger than or equal to the preset sliding current or not when the hydraulic driving device moves to the sliding area;
the second circuit switching module is used for switching the current input into the electro-hydraulic proportional valve into the preset slide current if the current input into the electro-hydraulic proportional valve is greater than or equal to the preset slide current;
and the movement control module is used for continuously controlling the current input into the electro-hydraulic proportional valve to be the preset sliding current after switching the current input into the electro-hydraulic proportional valve to be the preset sliding current until the hydraulic driving device moves to the target position.
In one embodiment, the point position control device further includes: the second current judgment module is also used for judging whether the output current of the controller is greater than the preset sliding current when the hydraulic driving device moves to the sliding area; the dead-zone current reduction module is used for reducing the preset dead-zone current by a first value if the output current is greater than the preset slide current; the preset dead zone current is set according to the critical current of the hydraulic driving device.
In one embodiment, the point position control device further includes: the first current judgment module is also used for judging whether the output current of the controller is smaller than the preset sliding current in the deceleration stage of the movement of the hydraulic driving device; and the dead-zone current increasing module is used for increasing the preset dead-zone current by a first value if the output current is less than the preset slide current.
In one embodiment, the point position control device further includes: the sliding current reducing module is used for reducing a preset sliding current by a second value when the stop position of the hydraulic driving device crosses a target position in the forward moving direction, and meanwhile, adopting a reverse sliding current to slide in a reverse direction; and the reverse sliding current reducing module is used for reducing the preset reverse sliding current by a second value when the hydraulic driving device slides reversely to cross the target position under the action of the reverse sliding current.
In one embodiment, the point position control device further includes: the reverse sliding current switching module is used for switching the current input into the electro-hydraulic proportional valve into a preset reverse sliding current when the stop position of the hydraulic driving device crosses a target position in the forward moving direction; the movement control module is also used for continuously controlling the current input into the electro-hydraulic proportional valve to be preset reverse sliding current until the hydraulic driving device moves to the target position.
In one embodiment, the movement control module includes: the sliding current control unit is used for continuously controlling the current input into the electro-hydraulic proportional valve to be preset sliding current, and when the hydraulic driving device stops moving before reaching a target position, the sliding current control unit controls the current input into the electro-hydraulic proportional valve to be reduced and then controls the current input into the electro-hydraulic proportional valve to be increased sliding current; the increased sliding current is obtained by increasing a second value according to a preset sliding current; and the movement control unit is used for continuously controlling the magnitude of the current input into the electro-hydraulic proportional valve to be the increased slide current until the hydraulic driving device moves to the target position.
The sliding current control unit is also used for continuously controlling the current input into the electro-hydraulic proportional valve to be preset sliding current, and when the hydraulic driving device stops moving before reaching the target position, the current input into the electro-hydraulic proportional valve is controlled to be reduced to zero, and then the current input into the electro-hydraulic proportional valve is controlled to be increased sliding current.
In one embodiment, the hydraulic drive device moving process comprises an acceleration phase and a deceleration phase; the hydraulic driving device is controlled in an open loop mode in an acceleration stage, and controlled in a closed loop mode in a deceleration stage; or the moving process of the hydraulic driving device comprises an acceleration stage, a constant speed stage and a deceleration stage; the hydraulic driving device is controlled in an open loop mode in an acceleration stage and a constant speed stage, and is controlled in a closed loop mode in a deceleration stage.
For specific definition of the point location control device, reference may be made to the definition of the point location control method above, and details are not described here. The respective modules in the dot location control device can be wholly or partially implemented by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
In one embodiment, there is provided a hydraulic control system including: the hydraulic proportional valve, the hydraulic driving device and the position sensor are arranged on the hydraulic proportional valve; the hydraulic driving device is a hydraulic motor or a hydraulic oil cylinder.
In one embodiment, a work vehicle is provided, which comprises the hydraulic control system of the above embodiment.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical storage, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A point location control method, the method comprising:
judging whether the current input into the electro-hydraulic proportional valve is smaller than a preset sliding current or not before the hydraulic driving device moves to a sliding area in a deceleration mode; the sliding area is in a deceleration stage in the moving process of the hydraulic driving device, and the moving area of the hydraulic driving device, which is less than a preset value from the target position, is used as the sliding area;
if the current input into the electro-hydraulic proportional valve is smaller than the preset sliding current, switching the current input into the electro-hydraulic proportional valve to be the preset sliding current;
when the hydraulic driving device moves to a sliding area, judging whether the current input into the electro-hydraulic proportional valve is larger than or equal to a preset sliding current;
if the current input into the electro-hydraulic proportional valve is larger than or equal to the preset sliding current, switching the current input into the electro-hydraulic proportional valve to be the preset sliding current;
and after the current input into the electro-hydraulic proportional valve is switched to be the preset slide current, continuously controlling the current input into the electro-hydraulic proportional valve to be the preset slide current until the hydraulic driving device moves to the target position.
2. The method of claim 1, further comprising:
judging whether the output current of the controller is greater than a preset sliding current or not when the hydraulic driving device moves to a sliding area;
if the output current is larger than the preset slide current, reducing the preset dead zone current by a first value; the preset dead zone current is set according to the critical current of the hydraulic driving device.
3. The method of claim 1, further comprising:
judging whether the output current of the controller is smaller than a preset sliding current or not in the deceleration stage of the movement of the hydraulic driving device;
if the output current is smaller than the preset slide current, increasing the preset dead zone current by a first value; the preset dead zone current is set according to the critical current of the hydraulic driving device.
4. The method of claim 1, wherein after continuously controlling the magnitude of the current input to the electro-hydraulic proportional valve to be the preset coasting current until the hydraulic drive device moves to the target position, the method comprises:
when the stop position of the hydraulic driving device crosses the target position in the forward moving direction, reducing the preset sliding current by a second value, and adopting a reverse sliding current to perform reverse sliding;
and when the hydraulic driving device slides reversely to cross the target position under the action of the reverse sliding current, reducing the preset reverse sliding current by a second value.
5. The method of claim 1, wherein after continuously controlling the magnitude of the current input to the electro-hydraulic proportional valve to be the preset coasting current until the hydraulic drive device moves to the target position, the method comprises:
when the stop position of the hydraulic driving device crosses a target position in the forward moving direction, switching the current input into the electro-hydraulic proportional valve into a preset reverse sliding current;
and continuously controlling the current input into the electro-hydraulic proportional valve to be preset reverse sliding current until the hydraulic driving device moves reversely to the target position.
6. The method of claim 1, wherein continuously controlling the magnitude of the current input to the electro-hydraulic proportional valve to be a preset coasting current until the hydraulic drive device moves to the target position comprises:
continuously controlling the magnitude of current input into the electro-hydraulic proportional valve to be preset sliding current, and when the hydraulic driving device stops moving before reaching a target position, controlling the magnitude of the current input into the electro-hydraulic proportional valve to be increased sliding current after the current input into the electro-hydraulic proportional valve is reduced; the increased sliding current is obtained by increasing a second value according to a preset sliding current;
and continuously controlling the magnitude of the current input into the electro-hydraulic proportional valve to be the increased coasting current until the hydraulic driving device moves to the target position.
7. The method of claim 6, wherein the continuously controlling the magnitude of the current input to the electro-hydraulic proportional valve to be a preset coasting current, and when the hydraulic drive device stops moving before reaching the target position, the controlling the magnitude of the current input to the electro-hydraulic proportional valve is increased after the current input to the electro-hydraulic proportional valve is reduced, and the method comprises the following steps:
and continuously controlling the magnitude of the current input into the electro-hydraulic proportional valve to be a preset sliding current, and when the hydraulic driving device stops moving before reaching the target position, controlling the magnitude of the current input into the electro-hydraulic proportional valve to be an increased sliding current after the current input into the electro-hydraulic proportional valve is reduced to zero.
8. The method according to any one of claims 1 to 7, wherein the hydraulic drive means movement process comprises an acceleration phase and a deceleration phase; the hydraulic driving device is controlled in an open loop mode in an acceleration stage, and controlled in a closed loop mode in a deceleration stage; or the like, or, alternatively,
the moving process of the hydraulic driving device comprises an acceleration stage, a constant speed stage and a deceleration stage; the hydraulic driving device is controlled in an open loop mode in an acceleration stage and a constant speed stage, and is controlled in a closed loop mode in a deceleration stage.
9. A hydraulic control system comprising a controller, a hydraulic proportional valve, the hydraulic drive of any one of claims 1-8, and a position sensor;
the hydraulic driving device is a hydraulic motor or a hydraulic oil cylinder.
10. A work vehicle comprising the hydraulic control system of claim 9.
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