Automatic leveling control method and control system for aerial work platform

Abstract

The invention relates to the field of risk control of high-altitude special equipment, in particular to an automatic leveling control method and system for an aerial work platform. In the lifting process of the working platform, a platform inclination angle, a main arm platform included angle and a main arm lifting angle are collected in real time, and a platform inclination angle calculation value is calculated by utilizing the main arm platform included angle and the main arm lifting angle according to the geometrical relationship among the three angles when the working platform is horizontal; and the difference value between the calculated value of the inclination angle of the platform and the collected inclination angle of the platform is used as a measurement value of the oscillation degree of the working platform and is used as a feedback parameter of a closed-loop control algorithm, and automatic leveling of the aerial work platform is achieved through closed-loop control. According to the scheme, oscillation errors caused by single detection depending on a platform tilt angle sensor can be avoided, and the leveling control effect is improved.

Description

Technical Field

[0001] The present invention relates to an automatic leveling control method and control system for an aerial work platform, in particular to a method and system for reducing vibration of the aerial work platform during operation based on a closed-loop control algorithm, belonging to the field of risk control of aerial special equipment. Background Art

[0002] The hanging basket is a kind of engineering machinery used for aerial work, which can reduce labor intensity, improve work efficiency, and can be reused. The hanging basket is connected to the end of the main arm, and together with the main arm and the platform, it forms an aerial work platform. During the operation of the aerial work platform, the main arm rises relative to the base to send the hanging basket and the workers on the hanging basket to the specified height for work. In the field of tunnel construction, facing construction conditions such as charging, arch erection, and inspection in the tunnel, operators are required to use aerial work platforms. In order to ensure the safety and comfort of the operators, the hanging basket needs to be kept horizontal at all times during the lifting and lowering process. The automatic leveling system of the hanging basket is particularly important in this process.

[0003] At present, the mainstream solution in the industry is to use an inclination sensor to measure the inclination angle of the work platform. When a certain inclination angle is generated, a controller is used to control the work platform leveling cylinder for leveling. There is a time lag, and the aerial work platform faces the problem of shaking and oscillation during leveling.

[0004] The Chinese patent application publication with application publication number CN103550893A proposes a method of using the feedback component of the angular acceleration sensor to suppress the vibration and jitter of the work platform. However, as the angular acceleration increases in the jitter state, this method will have errors in the control signal of the inclination sensor, and it is difficult to select the parameters for suppressing vibration, which is prone to poor leveling follow-up.

[0005] The Chinese patent application publication with application publication number CN112850593A proposes a method to alleviate the leveling lag by using the PWM value obtained by linear operation of variable amplitude current. However, this linear control method will have oscillations during operation, resulting in jitter after leveling control, and poor leveling control effect. Summary of the invention

[0006] The present invention provides an automatic leveling control method and control system for an aerial work platform, which solves the problem of poor leveling control effect in the prior art.

[0007] A technical solution of an automatic leveling control method for an aerial work platform of the present invention comprises the following steps:

[0008] 1) During the lifting process of the working platform, the platform inclination angle θ of the working platform relative to the horizontal, the main arm platform angle β between the working platform and the main arm, and the main arm lifting angle α relative to the horizontal are collected in real time;

[0009] 2) According to the geometric relationship between the angle value of the platform inclination, the angle value of the main arm platform angle and the angle value of the main arm lifting angle in the balanced state of the working platform, the calculated value of the platform inclination is calculated using the angle value of the main arm platform angle and the angle value of the main arm lifting angle;

[0010] 3) The sum of the difference between the collected platform inclination angle value, the calculated platform inclination angle value and the platform inclination angle value is set to zero as the control target, and the work platform is leveled using closed-loop control.

[0011] Further, in step 3), the control target is: the average value of the platform inclination angle and the difference between the calculated value of the platform inclination angle and the angle value of the platform inclination angle is zero.

[0012] Furthermore, in step 3), the given value of the closed-loop control is zero, the feedback value is the average value of the angle value of the platform inclination and the difference between the calculated value of the platform inclination and the angle value of the platform inclination, the control object is the proportional valve of the leveling cylinder of the working platform, and the closed-loop control is achieved using PID control.

[0013] Furthermore, before step 3), it is also determined whether the oscillation of the working platform is within the suppressible range based on the difference between the calculated value of the platform inclination and the collected angle value of the platform inclination. If the oscillation of the working platform is within the suppressible range, step 3) is executed; otherwise, the operator is reminded to manually intervene in the control.

[0014] Furthermore, in step 2), the geometric relationship between the angle value of the platform inclination, the angle value of the main arm-platform angle and the angle value of the main arm lifting angle when the working platform is in a balanced state is: the angle value of the platform inclination is equal to the absolute value of the angle value of the main arm-platform angle plus the angle value of the main arm lifting angle minus 90 degrees.

[0015] Furthermore, in step 1), the platform inclination angle θ, the main arm-platform angle β and the main arm lifting angle α collected in several consecutive collection cycles are averaged and used as the angle value of the platform inclination angle, the angle value of the main arm-platform angle and the angle value of the main arm lifting angle.

[0016] Furthermore, the main arm platform angle β is obtained by an encoder arranged at the hinge between the working platform and the main arm.

[0017] Furthermore, the main arm lifting angle α is obtained by an encoder arranged at the hinge between the main arm and the base.

[0018] Furthermore, the closed-loop control also includes feedforward compensation, and the feedforward compensation is obtained according to the difference between the speed of lifting and lowering the main arm and the leveling speed.

[0019] An automatic leveling control system for an aerial work platform of the present invention comprises a processor, wherein the processor is used to execute a computer program to implement the steps of the automatic leveling control method for the aerial work platform as described above.

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides an automatic leveling control method for an aerial work platform and a corresponding control system. During the lifting process of the working platform, the platform inclination angle, the main arm platform angle and the main arm lifting angle are collected in real time. According to the geometric relationship between the three angles when the working platform is horizontal, the platform inclination angle calculation value is calculated using the main arm platform angle and the main arm lifting angle. The difference between the platform inclination angle calculation value and the collected platform inclination angle is used as a measurement value of the degree of oscillation of the working platform and as a feedback parameter of a closed-loop control algorithm. The automatic leveling of the aerial work platform is achieved through closed-loop control. This solution can avoid the oscillation error caused by relying on a single detection of the platform inclination sensor and improve the effect of leveling control. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the composition of the automatic leveling control system of the hanging basket of the present invention;

[0023] Figure 2 A structural diagram of an aerial work platform of the automatic leveling system of the hanging basket of the present invention;

[0024] Figure 3 It is a flow chart of the automatic leveling control method of the hanging basket of the present invention.

[0025] The figure includes: 1. The horizontal part of the L-shaped arm; 2. The inclination sensor of the working platform; 3. The angle encoder of the working platform; 4. The leveling cylinder; 5. The main arm; 6. The main arm lifting cylinder; 7. The main arm angle encoder; 8. The vertical part of the L-shaped arm; 9. The L-shaped arm horizontal extension cylinder; 10. The hanging basket. DETAILED DESCRIPTION

[0026] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0027] The idea of ​​the present invention is to judge the oscillation state of the working platform by combining the lifting angle of the main arm of the main arm, the angle between the main arm platform and the main arm, and the platform inclination angle relative to the horizontal, and the encoder can filter the shaking oscillation data to more accurately obtain the real-time inclination angle of the working platform; based on the detection data of the main arm angle encoder 7, the working platform angle encoder 3 and the working platform inclination sensor 2, a platform shaking oscillation model is established, and the controller judges the leveling oscillation state of the working platform and then executes the corresponding leveling method according to the oscillation state. At the same time, by detecting the difference in the changing angles of the main arm angle encoder 7 and the working platform angle encoder 3, the controller 14 controls the leveling of the working platform cylinder to introduce feedforward compensation to reduce the leveling lag.

[0028] System Example:

[0029] like Figure 1 As shown, the automatic leveling control system for the aerial work platform of this embodiment includes a work platform inclination sensor 2, a work platform angle encoder 3, a main arm angle encoder 7, a controller 14, an electromagnetic proportional valve 15 and a work platform leveling cylinder 4.

[0030] The controller 14 is respectively connected to the working platform inclination sensor 2 , the working platform angle encoder 3 and the main arm angle encoder 7 through CAN communication.

[0031] like Figure 2 As shown, the working platform inclination sensor 2 is arranged on the working platform to detect the inclination of the working platform relative to the horizontal in real time, and a main arm angle encoder 7 for detecting the lifting angle of the main arm and a working platform angle encoder 3 for detecting the main arm platform angle between the vertical part 8 of the L-shaped arm of the working platform and the main arm are respectively arranged at the hinge between the main arm 5 and the base and at the hinge between the working platform and the main arm 5.

[0032] The working platform includes an L-shaped arm and a hanging basket 10 arranged on the L-shaped arm transverse part 1. The hanging basket 10 can be extended and retracted by retracting the L-shaped arm horizontal extension cylinder 9. The main arm platform angle between the working platform and the main arm 5 detected by the working platform angle encoder 3 is the angle between the main arm 5 and the L-shaped arm vertical part 8.

[0033] The working platform inclination sensor 2 detects the inclination of the working platform relative to the horizontal in real time, the main arm angle encoder 7 detects the angle of the main arm 5 relative to the horizontal direction during the lifting process in real time, and the working platform angle encoder 3 detects the angle between the vertical part 8 of the L-shaped arm and the main arm 5 in real time; the working platform inclination sensor 2, the main arm angle encoder 7 and the working platform angle encoder 3 send the collected data to the controller 14.

[0034] The use of an encoder can filter the jitter and oscillation data and more accurately obtain the angle data corresponding to the working platform system. As other implementation methods, other sensors can also be used to collect the corresponding angles.

[0035] The controller 14 executes the automatic leveling control method of the aerial work platform of the present invention. The controller 14 combines the main arm lifting angle, the main arm platform angle and the platform inclination angle of the main arm to establish a platform shaking oscillation model; judges the leveling oscillation state during the lifting process of the work platform, and then generates a corresponding leveling signal according to the oscillation state, and outputs the leveling signal to the electromagnetic proportional valve 15. The electromagnetic proportional valve 15 controls the degree of closing and opening according to the leveling signal, and then controls the extension and contraction amount of the work platform leveling cylinder 4 to achieve automatic leveling of the work platform.

[0036] Furthermore, by utilizing the angle difference between the angle detection values ​​of the main arm angle encoder 7 and the working platform angle encoder 3, feedforward compensation is introduced into the leveling signal sent to the electromagnetic proportional valve 15, thereby reducing the leveling lag of the working platform leveling cylinder 4 during leveling.

[0037] like Figure 3 As shown, the automatic leveling control method of the aerial work platform specifically includes the following steps:

[0038] 1) The main arm angle encoder 7 detects the main arm lifting angle α relative to the horizontal direction during the lifting of the main arm 5 and sends it to the controller 14. The working platform angle encoder 3 detects the main arm platform angle β between the vertical part 8 of the L-shaped arm of the working platform and the main arm 5 and sends it to the controller 14;

[0039] The work platform inclination sensor 2 detects the inclination angle θ of the work platform relative to the horizontal platform in real time and sends it to the controller 14 .

[0040] 2) In step 1), the period T of the work platform inclination sensor 2, the main arm angle encoder 7 and the work platform angle encoder 3 to collect corresponding data is the same and fixed to reduce the error caused by the different distances between each sensor or encoder and the controller.

[0041] Due to the error between sensors and the deformation between the actual boom structures, in order to reduce the deviation of the angle value, as another embodiment, the controller 4 can further perform mean processing on the following data collected by each sensor and encoder: the main arm lifting angle α relative to the horizontal direction during the lifting process of the main arm 5, the main arm platform angle β between the vertical part 8 of the L-shaped arm of the working platform and the main arm 5, and the platform inclination angle θ of the working platform relative to the horizontal direction according to formula (1):

[0042]

[0043] Among them, μ (n-1) , μ(n-2) , μ n Respectively represent the angle data collected by the encoder or sensor of the previous cycle, the previous two cycles and the current cycle, Indicates the mean value of the angles collected at the current moment.

[0044] 3) Determine the action of the main arm 5. If the controller 14 detects that the main arm 5 is rising or falling, the subsequent steps are continued to be executed, otherwise, step 1 is executed.

[0045] 4) Calculate the deviation value. Theoretically, when the working platform is in a balanced state (i.e., when the working platform is horizontal), the main arm lifting angle α relative to the horizontal direction during the lifting process of the main arm 5, the main arm platform angle β between the vertical part 8 of the L-shaped arm of the working platform and the main arm 5, and the platform inclination angle θ of the working platform relative to the horizontal direction satisfy the following relationship:

[0046] θ=|α+β-90°| (2)

[0047] However, due to mechanical reasons of the system itself, the system may vibrate during operation. There will be a deviation between the result calculated by the controller 14 for the main arm lifting angle α and the main arm platform angle β according to formula (2), that is, the calculated value of the platform inclination angle, and the platform inclination angle θ detected in real time by the working platform inclination sensor 2.

[0048] In order to minimize the calculation deviation caused by the factors that cannot be eliminated by the system itself, the controller 14 processes the main arm lifting angle α, the main arm platform angle β and the platform inclination angle θ according to formula (1) to calculate the main arm lifting angle α and the main arm lifting angle mean value The main boom platform angle β is the average of the main boom platform angles. and the platform inclination angle θ Main arm lifting angle average Mean angle between the main arm platform and the Substituting into formula (2) to obtain the calculated value of platform inclination θ′, the average platform inclination Subtract the calculated value of the platform inclination θ′ to get the difference Δe, that is:

[0049]

[0050] The difference Δe reflects the degree of jitter and oscillation of the work platform due to mechanical reasons that the system itself cannot eliminate. The difference Δe of zero can be used as a control target to achieve automatic leveling control of the aerial work platform.

[0051] 5) As another implementation, before controlling, it is also possible to first determine whether the current vibration is within the ability of the system of the present invention to suppress vibration. If not, it can directly remind the operator to manually intervene in the control.

[0052] When the working platform shakes and oscillates, the value of the working platform inclination sensor 2 fluctuates greatly, while the main arm angle encoder 7 and the working platform angle encoder 3 can filter out the value fluctuations caused by factors such as shaking that the system itself cannot eliminate. At this time, the difference Δe calculated in step 4) will only be affected by the value fluctuations of the working platform inclination sensor 2. At this time, the difference Δe can be used as a measure of the shaking and oscillation state of the working platform.

[0053] Specifically, the method for determining whether the controller 14 can eliminate the vibration of the working platform when the working platform vibrates includes:

[0054] Through offline calibration, we find that the working platform oscillates greatly and the automatic leveling control system can no longer suppress the oscillation of the working platform. The difference Δe calculated according to formula (3) is set as the upper limit value e of the working platform oscillation. k When Δe>e k When Δe <e k When the platform is level, the average of the inclination angles θ and Δe relative to the horizontal (θ+Δe) / 2 is taken as the actual angle deviation value of the working platform and sent to the controller 14. The controller 14 uses a closed-loop control algorithm to calculate the leveling signal, and then controls the leveling of the working platform.

[0055] Specifically, the controller 14 uses a closed-loop control algorithm as the leveling algorithm. The specific calculation method is as follows: The angle deviation value e calculated by formula (3) is k The function e(t) about time is calculated by the proportional model, integral model and differential model to obtain the three control components of proportion, integration and differentiation, and the calculated three control components of proportion, integration and differentiation are synthesized into a control signal u(t) to control the electromagnetic proportional valve 15 in the leveling control system. The proportional model, integral model and differential model and the synthesis method can be expressed as the formula:

[0056]

[0057] Among them, K p is the proportional coefficient in the proportional model, reflecting the adjustment speed; T1 is the integral coefficient in the integral model, indicating the integral time, reflecting the relationship between the current value and the previous T1 cycles; T D is the differential time constant in the differential model, which reflects the correction strength of the system.

[0058] The actual output control parameter of the controller 14 is the PWM duty cycle, which controls the opening of the electromagnetic proportional valve 15 and thus controls the extension and retraction of the working platform leveling cylinder 4 to achieve the purpose of leveling. However, the classic closed-loop control adjustment model based on the horizontal inclination angle deviation value of the working platform can only be controlled when the angle deviation value occurs. Moreover, although the differential model in the classic closed-loop control algorithm model can predict the trend of the working platform angle deviation, it cannot fundamentally solve the lag problem of the classic closed-loop control algorithm model. During the leveling process, the working platform is prone to switch between the leading and lagging states.

[0059] In order to further solve the hysteresis disadvantage of the classic closed-loop control algorithm model leveling, as another implementation method, a feedforward compensation mechanism can be further used, as follows:

[0060] During the lifting process of the main arm, the rising or falling state of the main arm can be distinguished according to the changing trend of the main arm angle. In the rising state, in the ideal state where the working platform completely follows the main arm, in order to keep the platform inclination angle θ measured by the working platform inclination sensor at 0, the leveling angular velocity of the working platform leveling cylinder 4 should be equal to the rising angular velocity of the main arm, that is, the change value of the lifting angle α of the main arm 5 in each cycle time is equal to the change value of the inclination angle θ of the working platform. The greater the difference between the leveling angular velocity of the working platform leveling cylinder 4 and the rising angular velocity of the main arm, the greater the trend of the inclination angle of the working platform (reflected as the platform inclination angle θ). The value f(t) is taken as the inclination velocity of the working platform. Feedforward compensation is introduced in the traditional control model of the closed-loop control algorithm. The difference between the lifting speed of the main arm and the speed of the leveling cylinder is selected as the feedforward compensation. Its expression is:

[0061] f(t)=K*(dα / dt-dθ / dt) (5)

[0062] Among them, K is the feedforward coefficient, dα / dt represents the speed of the main arm lifting and lowering, and dθ / dt represents the speed of the leveling cylinder.

[0063] The actual output y(t) of the controller is:

[0064] y(t)=u(t)+f(t) (6)

[0065] As a result, when the main arm starts to rise, the angular velocity of the main arm is greater than the angular velocity of the leveling cylinder of the working platform, y(t) increases, the speed of the leveling cylinder increases, and the controller 14 can advance the corresponding control output according to the size of the speed difference f(t) to achieve rapid response and reduce the angle difference; the angular velocity of the main arm is less than the angular velocity of the leveling cylinder of the service platform, y(t) decreases, and the feedforward compensation f(t) can suppress the actual output of the controller in advance, suppress the leveling cylinder speed, and reduce the overshoot of the control system.

[0066] Method Example:

[0067] The automatic leveling control method for an aerial work platform of this embodiment has been clearly introduced in the system embodiment and will not be repeated here.

[0068] The method of the present invention can avoid the oscillation error caused by relying on a single detection of the platform inclination sensor, and at the same time introduces feedforward compensation on the basis of PID regulation to solve the hysteresis caused by PID regulation relying on angle error, and more accurately control the automatic leveling of the hanging basket.

Claims

1. A method for automatically leveling an aerial work platform, characterized in that: The steps include: 1) During the lifting process of the working platform, the platform inclination angle θ of the working platform relative to the horizontal, the main arm platform angle β between the working platform and the main arm, and the main arm lifting angle α relative to the horizontal are collected in real time; 2) According to the geometric relationship between the angle value of the platform inclination, the angle value of the main arm platform angle and the angle value of the main arm lifting angle in the balanced state of the working platform, the calculated value of the platform inclination is calculated using the angle value of the main arm platform angle and the angle value of the main arm lifting angle; 3) The sum of the difference between the collected platform inclination angle value, the calculated platform inclination angle value and the platform inclination angle value is zero as the control target, and the work platform is leveled using closed-loop control.

2. The automatic leveling control method for an aerial work platform according to claim 1, characterized in that: In step 3), the control target is: the average value of the platform inclination angle and the difference between the calculated value of the platform inclination angle and the angle value of the platform inclination angle is zero.

3. The automatic leveling control method for an aerial work platform according to claim 2, characterized in that: In step 3), the given value of the closed-loop control is zero, the feedback value is the average value of the platform inclination angle and the difference between the calculated value of the platform inclination angle and the angle value of the platform inclination angle, the controlled object is the proportional valve of the leveling cylinder of the working platform, and the closed-loop control is achieved by PID control.

4. The automatic leveling control method for an aerial work platform according to claim 3, characterized in that: Before step 3), it is also determined whether the oscillation of the working platform is within the suppressible range based on the difference between the calculated value of the platform inclination and the collected angle value of the platform inclination. If the oscillation of the working platform is within the suppressible range, step 3) is executed; otherwise, the operator is reminded to manually intervene in the control.

5. The automatic leveling control method for an aerial work platform according to any one of claims 1 to 4, characterized in that: In step 2), the geometric relationship between the angle value of the platform inclination, the angle value of the main arm platform angle and the angle value of the main arm lifting angle when the working platform is in a balanced state is: the angle value of the platform inclination is equal to the absolute value of the angle value of the main arm platform angle plus the angle value of the main arm lifting angle minus 90 degrees.

6. The automatic leveling control method for an aerial work platform according to claim 5, characterized in that: In step 1), the platform inclination angle θ, the main arm platform angle β and the main arm lifting angle α collected in several consecutive collection cycles are averaged and used as the angle value of the platform inclination angle, the angle value of the main arm platform angle and the angle value of the main arm lifting angle.

7. The automatic leveling control method for an aerial work platform according to claim 1, characterized in that: The main arm platform angle β is obtained by an encoder arranged at the hinge between the working platform and the main arm.

8. The automatic leveling control method for an aerial work platform according to claim 1, characterized in that: The main arm lifting angle α is obtained by an encoder arranged at the hinge between the main arm and the base.

9. The automatic leveling control method for an aerial work platform according to claim 1, characterized in that: The closed-loop control also includes feed-forward compensation, which is obtained according to the difference between the speed of lifting and lowering the main arm and the leveling speed.

10. An automatic leveling control system for an aerial work platform, comprising a processor, characterized in that: The processor is used to execute a computer program to implement the steps of the automatic leveling control method for an aerial work platform as described in any one of claims 1 to 6.

Images