S-curve start-stop control system and method for crane based on digital hydraulic slewing

Abstract

The invention discloses an S-curve start-stop control system for a crane based on digital hydraulic rotation, including a handle input device, a controller, a driver, a stepper motor and a digital hydraulic motor connected in sequence, and also discloses a control method based on the above system, inputting a set value and collecting an input operation signal of the handle input device; the controller calculates a control signal through an S-curve algorithm according to the input operation signal and the input set value; the driver outputs a driving signal according to the control signal to drive the stepper motor to rotate; the stepper motor drives the digital hydraulic motor to operate, and the digital hydraulic motor controls the speed and angle of platform rotation. By adopting the above system and method, the rotation speed of the digital hydraulic motor is controlled by the speed of the stepper motor, and the rotation angle of the digital hydraulic motor is controlled by the displacement of the stepper motor. The S-curve start-stop control of the stepper motor can realize the S-curve start-stop smooth control of the crane rotation, thereby realizing a smooth, safe and efficient hoisting control task.

Description

Technical Field

[0001] The present invention relates to the technical field of crane control, and in particular to an S-curve start-stop control system and method for a crane based on digital hydraulic rotation. Background Art

[0002] Traditional truck cranes require skilled operators to operate large-scale lifting, and there will be low operating efficiency in order to ensure smooth slewing operation. This is because the traditional hydraulic transmission system cannot effectively adjust the speed accurately. In order to ensure smooth slewing operation, the operator will often be cautious to reduce the operating speed and sacrifice operating efficiency to achieve stability. The specific technical reason for these shortcomings is that most traditional hydraulic control speed regulation uses electric proportional valve control, and the current signal is converted into an electromagnetic force signal to drag the valve core, which itself has a large delay. In addition, the valve core opening controlled by the current signal is nonlinear due to the mechanical friction resistance and the change in oil viscosity with temperature, which makes the speed regulation uncontrollable. In addition, at low speeds at the beginning and end of the start and stop, the valve port micro-motion control performance is poor due to the instability of the current analog signal output and the change in mechanical resistance. Under such poor hydraulic control accuracy, generally only the simplest linear buffer speed adjustment method is used, and the acceleration change and jerk impact of linear adjustment at the moment of starting and stopping are very large, resulting in the inability of the crane to start and stop smoothly. Achieving stable lifting relies too much on the experience of crane operators, and the training cycle for skilled crane operators is long. The linear buffer start-stop control has a large impact at the start and stop, which leads to system instability. The existing high-precision control system has a complex structure, a high failure rate in harsh working conditions, is difficult to maintain, and has a high manufacturing cost, which is not suitable for the harsh working conditions of construction machinery. Summary of the invention

[0003] The purpose of the present invention is to provide an S-curve start-stop control system and method for a crane based on digital hydraulic rotation. The rotation speed of the digital hydraulic motor is controlled by the speed of a stepper motor, and the rotation angle of the digital hydraulic motor is controlled by the displacement of the stepper motor. The S-curve start-stop control of the stepper motor can achieve smooth S-curve start-stop control of the crane rotation, thereby achieving a smooth, safe and efficient lifting control task.

[0004] To achieve the above object, the present invention provides an S-curve start-stop control system for a crane based on digital hydraulic rotation, comprising:

[0005] A handle input device, used for collecting input operation signals;

[0006] A controller, which calculates a control signal according to the collected operation signal;

[0007] A driver, used for receiving a control signal and outputting a drive signal;

[0008] Stepper motor, used to drive digital hydraulic motor;

[0009] Digital hydraulic motor, used to drive the platform to rotate;

[0010] The handle input device is connected to the controller, the controller is connected to the driver, the driver is connected to the stepper motor, the stepper motor is connected to the digital hydraulic motor, and the digital hydraulic motor is connected to the platform.

[0011] A control method for the S-curve start-stop control system based on the above crane based on digital hydraulic slewing, the specific steps are as follows:

[0012] Step S1: input the set value and collect the input operation signal of the handle input device;

[0013] Step S2: The controller calculates a control signal through an S-curve algorithm according to the input operation signal and the input setting value;

[0014] Step S3: the driver outputs a driving signal according to the control signal to drive the stepping motor to rotate;

[0015] Step S4: The stepper motor drives the digital hydraulic motor to operate, and the digital hydraulic motor controls the speed and angle of rotation of the platform.

[0016] Preferably, in step S2, the calculation formula of the S-curve algorithm is as follows:

[0017] v=(1-B)x-1 / (2π)*cos(2π(1-B)x+2πB-π / 2)+B

[0018] In the formula, x∈(0,1), v∈(-1 / (2π)*cos(2πB-π / 2)+B,1), B∈(0,1), B=angle / 360 or radian / 2π, where angle is the given intercept angle and radian is the given intercept radian.

[0019] Preferably, the rotation speed of the stepper motor is positively correlated with the rotation speed and angle of the digital hydraulic motor.

[0020] Preferably, the input setting value is a given interception angle or a given interception arc.

[0021] Therefore, the present invention adopts the above-mentioned S-curve start-stop control system and method based on digital hydraulic rotation of a crane, which has the following beneficial effects:

[0022] (1) The rotation speed of the digital hydraulic motor is controlled by the stepper motor speed, and the rotation angle of the digital hydraulic motor is controlled by the stepper motor displacement to improve the control accuracy.

[0023] (2) There is a positive correlation between the stepper motor and the digital hydraulic motor. The S-curve start-stop control of the stepper motor can achieve smooth S-curve start-stop control of the crane rotation, increase the take-off speed, and improve the speed regulation efficiency, thereby achieving a smooth, safe and efficient lifting control task.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of an S-curve start-stop control system based on digital hydraulic rotation of a crane of the present invention;

[0026] Figure 2 This is a flow chart of the control method of the present invention;

[0027] Figure 3 It is a curve without a take-off value (B=0);

[0028] Figure 4 This is a curve with a take-off value (B=0.2). DETAILED DESCRIPTION

[0029] Example

[0030] Figure 1 The present invention is a structural schematic diagram of an S-curve start-stop control system for a crane based on digital hydraulic rotation. As shown in the figure, an S-curve start-stop control system for a crane based on digital hydraulic rotation includes:

[0031] A handle input device, used for collecting input operation signals;

[0032] A controller, which calculates a control signal according to the collected operation signal;

[0033] A driver, used for receiving a control signal and outputting a drive signal;

[0034] Stepper motor, used to drive digital hydraulic motor;

[0035] Digital hydraulic motor is used to drive the platform to rotate.

[0036] The handle input device is connected to the controller to transmit the input operation signal to the controller for relevant calculation. The controller is connected to the driver to send the control signal to the driver. The driver is connected to the stepper motor, and the stepper motor is connected to the digital hydraulic motor. The speed of the stepper motor is positively correlated with the speed and angle of the digital hydraulic motor. The digital hydraulic motor is controlled by the stepper motor to improve the control accuracy. The digital hydraulic motor is connected to the platform to drive the rotation of the platform.

[0037] A control method for the S-curve start-stop control system based on the above crane based on digital hydraulic slewing, the specific steps are as follows:

[0038] Step S1: input a setting value and an input operation signal of a collection handle input device, wherein the input setting value is a given interception angle or a given interception arc.

[0039] Step S2: The controller calculates a control signal using an S-curve algorithm according to the input operation signal and the input setting value.

[0040] The calculation formula of the S-curve algorithm is as follows:

[0041] v=(1-B)x-1 / (2π)*cos(2π(1-B)x+2πB-π / 2)+B

[0042] In the formula, x∈(0,1), v∈(-1 / (2π)*cos(2πB-π / 2)+B,1), B∈(0,1), B=angle / 360 or radian / 2π, where angle is the given intercept angle and radian is the given intercept radian.

[0043] Let acceleration be a=1+sin x,x∈(-π / 2,3π / 2);

[0044] Derivative of acceleration: j = a' = (1 + sin x)' = cos x;

[0045] Substituting x=3π / 2 into the above two formulas, we get: acceleration a=0, jerk=0;

[0046] Integrating the acceleration yields: v = ∫adx = ∫(1+sinx)dx, x∈(-π / 2,3π / 2);

[0047] Solving the above velocity formula, we get: v = x-cos x + c, x∈(-π / 2,3π / 2), substituting c = π / 2, and compressing it 2π times along the vertical axis for convenience of calculation, we get the following formula:

[0048] v=1 / (2π)*((x-cos x)+π / 2)=1 / (2π)*(x-cos x)+1 / 4,

[0049] Then when x∈(-π / 2,3π / 2), then v∈(0,1);

[0050] Shift x right by π / 2, and we get the following formula, x∈(0,2π), v∈(0,1):

[0051] v=1 / (2π)*(x-π / 2-cos(x-π / 2))+1 / 4=1 / (2π)*(x-cos(x-π / 2));

[0052] Compressing x by 2π, we get the following final formula, x∈(0,1), v∈(0,1):

[0053] v=1 / (2π)*(2πx-cos(2πx-π / 2)), which is the S-curve control calculation formula without interception and take-off.

[0054] In actual application, the motor speed changes from 0 to Vmotor by simply multiplying the speed curve v by the proportional coefficient Vmotor.

[0055] Assume that the take-off distance of segment B is intercepted, B∈(0,1);

[0056] If the interception angle angle is given, then B = angle / 360;

[0057] If the intercept radian is given, then B = radian / 2π;

[0058] To ensure that x still starts from 0, first translate the curve to the negative direction of the x-axis by a distance B:

[0059] v=1 / (2π)*(2π(x+B)-cos(2π(x+B)-π / 2))=(1 / 2π)*(2πx-cos(2π(x+B)-π / 2))+B

[0060] Where x∈(0,1-B), v∈(0,1);

[0061] To ensure that x still varies from 0 to 1, stretch the curve along the x-axis by 1 / (1-B) times:

[0062] v=1 / (2π)*(2π(1-B)x-cos(2π((1-B)x+B)-π / 2))+B

[0063] =(1-B)x-1 / (2π)*cos(2π(1-B)x+2πB-π / 2)+B

[0064] The final S-curve formula is:

[0065] v=(1-B)x-1 / (2π)*cos(2π(1-B)x+2πB-π / 2)+B

[0066] x∈(0,1), v∈(-1 / (2π)*cos(2πB-π / 2)+B,1)

[0067] Where B∈(0,1), B=angle / 360 or B=radian / 2π,

[0068] angle is the given intercept angle, radian is the given intercept radian,

[0069] When x=0, v=-1 / (2π)*cos(2πB-π / 2)+B,

[0070] When x=1, v=1,

[0071] When the S-curve control calculation formula is not performed for interception and take-off, it is as follows:

[0072] v=1 / (2π)*(2πx-cos(2πx-π / 2)).

[0073] Figure 3 It is a curve without the interception value of the take-off amount (B=0), as shown in the figure, x∈(0,1), v∈(0,1), when x is 0, that is, at the moment of starting, the speed v, acceleration a, jerk j, etc. are all 0, and it can be started in a very smooth way. When x is 1, that is, at the end of the speed increase, the acceleration a, jerk j, etc. are still all 0, and the acceleration stage can be ended in a very smooth way to maintain the final high-speed operation. Therefore, the result calculated by the above method controls the speed of the stepper motor, and a very smooth crane slewing platform rotation control effect can be obtained through the linear relationship between the speed of the stepper motor and the digital hydraulic motor.

[0074] The calculation formula for the improved S-curve control with intercepted takeoff is as follows:

[0075] v=(1-B)x-1 / (2π)*cos(2π(1-B)x+2πB-π / 2)+B

[0076] Figure 4 is a curve with a take-off value (B = 0.2), such as Figure 4 As shown, x∈(0,1), v∈(-1 / (2π)*cos(2πB-π / 2)+B,1), a=v'=(1-B)*(1+sin(2π(1-B)x+2πB-π / 2)), j=a'=2π(1-B)2cos(2π(1-B)x+2πB-π / 2), when x is 0, that is, the moment of starting, the take-off speed v=-1 / (2π)*cos(2πB-π / 2)+B, at this time the acceleration a=(1-B)*(1+sin(2πB-π / 2)), jerk j=2π(1-B)2cos(2πB-π / 2), as shown Figure 4As shown, the interception angle is generally less than 10 degrees, that is, B<0.028, at this time a<0.015, j<1.04, it can still start in a relatively smooth way, because there is a take-off speed, so the start time will not be too long. When x=1 is at the end of acceleration, at this time v=1, a=0, j=0, it can still end the acceleration stage in a very smooth way, so that the system maintains high-speed and stable operation.

[0077] Step S3: the driver outputs a driving signal according to the control signal to drive the stepping motor to rotate;

[0078] Step S4: The stepper motor drives the digital hydraulic motor to operate, and the digital hydraulic motor controls the speed and angle of rotation of the platform.

[0079] Therefore, the present invention adopts the above-mentioned S-curve start and stop control system and method based on digital hydraulic rotation of the crane, in which the stepper motor is positively correlated with the digital hydraulic motor. The S-curve start and stop control of the stepper motor can realize the smooth control of the S-curve start and stop of the crane rotation, increase the take-off speed, and improve the speed regulation efficiency, thereby realizing a smooth, safe and efficient lifting control task.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A crane S-curve start-stop control system based on digital hydraulic rotation, characterized in that: include A handle input device, used for collecting input operation signals; A controller, which calculates a control signal according to the collected operation signal; A driver, used for receiving a control signal and outputting a drive signal; Stepper motor, used to drive digital hydraulic motor; Digital hydraulic motor, used to drive the platform to rotate; The handle input device is connected to the controller, the controller is connected to the driver, the driver is connected to the stepper motor, the stepper motor is connected to the digital hydraulic motor, and the digital hydraulic motor is connected to the platform; Based on a control method of an S-curve start-stop control system of a crane based on digital hydraulic rotation, the specific steps are as follows: Step S1: input the set value and collect the input operation signal of the handle input device; Step S2: The controller calculates the control signal through the S-curve algorithm according to the input operation signal and the input setting value; in step S2, the calculation formula of the S-curve algorithm is as follows: v=(1-B)x-1 / (2π)*cos(2π(1-B)x+2πB-π / 2)+B Where, x∈(0,1), v∈(-1 / (2π)*cos(2πB-π / 2)+B,1), B∈(0,1), B=angle / 360 or radian / 2π, where angle is the given intercept angle and radian is the given intercept radian; Step S3: the driver outputs a driving signal according to the control signal to drive the stepper motor to rotate; Step S4: The stepper motor drives the digital hydraulic motor to operate, and the digital hydraulic motor controls the speed and angle of rotation of the platform.

2. A crane S-curve start-stop control system based on digital hydraulic slewing according to claim 1, characterized in that: The rotation speed of the stepper motor is positively correlated with the rotation speed and angle of the digital hydraulic motor.

3. A crane S-curve start-stop control system based on digital hydraulic rotation according to claim 2, characterized in that: The input setting value is a given interception angle or a given interception arc.

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