阅读说明：本技术 一种起重机同步误差测量装置及其纠偏方法 (Crane synchronization error measuring device and deviation rectifying method thereof ) 是由 胡志华 王耀宗 张馨蓉 李照章 祁明艳 于 2020-07-15 设计创作，主要内容包括：本发明公开了一种起重机同步误差测量装置,包含：第一类同步误差测量装置,设置有绝对值编码器；第一类同步误差,为起重机的左右两侧车轮位置控制器提供位置偏差输入；第二类同步误差测量装置,设置在两个车轮上侧；第二类同步误差,为车轮中心线相对于轨道中心线的偏转角；为了同时纠正两类同步误差,设计以交叉耦合同步控制策略为核心的起重机纠偏方法,位置控制器同时接收两类同步误差信号,共同参与控制器的调节,纠正偏差。本发明解决了起重机在工作状态中的同步误差的测量及其位置纠偏；控制系统具有响应快、平稳性好等良好的控制性能；具有结构简单、成本低廉、可靠性高、便于维护等特点。(The invention discloses a synchronous error measuring device of a crane, comprising: the first type of synchronous error measuring device is provided with an absolute value encoder; the first type of synchronous error provides position deviation input for wheel position controllers on the left side and the right side of the crane; the second type synchronous error measuring device is arranged on the upper sides of the two wheels; the second type of synchronous error is a deflection angle of a wheel center line relative to a track center line; in order to correct two types of synchronous errors simultaneously, a crane deviation correction method taking a cross-coupling synchronous control strategy as a core is designed, and a position controller receives two types of synchronous error signals simultaneously, participates in the adjustment of the controller together and corrects the deviation. The invention solves the problems of measurement of synchronous error and position deviation correction of the crane in the working state; the control system has good control performance such as quick response, good stability and the like; the device has the characteristics of simple structure, low cost, high reliability, convenience in maintenance and the like.)

1. A crane synchronization error measuring device, comprising:

the left and right main motors (13, 18) are connected through a belt to form left and right transmission devices (14, 19) respectively; the left and right transmission devices (14, 19) respectively drive the crane cart (1) to realize reciprocating motion on the track (7);

the positions of the wheels (6) on the two sides of the crane are calibrated before the crane is driven; the position calibrated before driving is used as the output position (15, 20) when the crane is driven and fed back to the input ends (12, 17) of the position controllers at the left side and the right side;

the first type of synchronous error measuring devices (3) are absolute value encoders and are respectively arranged on the main motors (2) at the left side and the right side; the first type of synchronization error is defined as: the difference between the current left and right absolute value encoder values (16, 21) and the input position (11); the first type of synchronous error value is respectively used as part of input of left and right position controllers (12, 17) to participate in the adjustment of the controllers;

The second type synchronous error measuring devices (5) are respectively arranged on the upper sides of the left and right wheels (6); the second type of synchronization error is defined as: the deviation distance between the central line of the wheel (6) and the central line of the track (7); the second type synchronous error measuring device is provided with a parallel plate capacitor, a certain direct current voltage is applied to two ends of polar plates (8 and 9) of the parallel plate capacitor for charging, after the charging is finished, the charged parallel plate capacitor generates a corresponding voltage value according to the distance change between the polar plates, and the voltage value is converted into a specific synchronous error value;

the second type of synchronous error measuring device (5) transmits the distance of the central line of the wheel (6) deviating from the central line of the track (7) to one plate (8) of the parallel plate capacitor through a lever mechanism, and is used for measuring the distance d between the two plates (8, 9) of the parallel plate capacitor; the distance d between the two polar plates is used as the input participating in calculating the deflection angle alpha;

converting the deviation distance between the center line of the crane wheel (6) and the center line of the track (7) into a deflection angle alpha by a second type of error measuring device; the deflection angle alpha is an additional feedback signal (23) which is used as the other part input of the left and right position controllers (12, 17) and participates in the adjustment of the controllers;

The input end of the controller has two types of signals, and the output end of the controller is respectively connected with a left main motor (13) and a right main motor (18); the first type of signal is the difference value between the output positions (15, 20) and the input position (11) of the main motors on the left side and the right side of the crane; the second type of signal is an additional signal (23) corresponding to the position deflection angles (22) of the cranes on the left side and the right side; the two types of signals of the input end simultaneously provide accurate deviation signals for the left and right side controllers, so that the tracking of the signals is realized.

2. A crane synchronous error measuring device according to claim 1, characterized by further comprising a laser range finder (4) as an absolute value encoder error self-correcting measuring device, arranged at the upper end of the first type of synchronous error measuring device (3).

3. A synchronous error correction method using the crane synchronous error measuring device according to any one of claims 1-2, comprising the steps of:

step 1: before the crane is driven, resetting the absolute value encoder and recalibrating the positions of two wheels (6) of the crane;

step 2: calculating a first type of synchronization error;

step 2.1: the absolute value encoder integrates the speed of the main motor (2) in time when the crane runs; determining the current positions (15, 20) of the cart mechanisms (1) at the left side and the right side for the travel distance of each wheel (6) according to the integration result;

Step 2.2: the current positions (15, 20) of the cart mechanisms (1) on the left side and the right side are respectively different from the input position (11), the difference value is used as a first type of synchronous error, and the type of error is respectively used as a part of the position controllers (12, 17) on the left side and the right side to be input;

and step 3: when the wheels (6) of the cart slip, the absolute value encoders (16, 21) have accumulated errors; the elimination of the accumulated error realizes the error self-correction of the absolute value encoders (16, 21) through the measurement result of the laser range finder (4);

step 3.1: if the error of the measured values of the absolute value encoder (3) and the laser range finder (4) exceeds the minimum critical deviation, the absolute value encoder (3) is corrected;

step 3.2: and if the deviation range is too large, the crane is required to stop, and the positions of the wheels (6) on the two sides are calibrated again.

And 4, step 4: calculating a second type synchronization error; when the wheel (6) deviates relative to the central line of the track (7), the deviation distance is measured by a parallel plate capacitor, and the converted distance is the deflection angle alpha; a step of calculating the deflection angle α, comprising:

step 4.1: knowing the dielectric coefficient and the electrostatic force constant k of the parallel plate capacitor and the dead area S of the two polar plates;

step 4.2: before the crane starts, the capacitor is charged, and the charge quantity carried by the fully charged capacitor is Q;

Step 4.3: calculating the capacitance value according to the distance d between the two current polar plates

Step 4.4: calculating the voltage between the two polar plates according to the current capacitance C

Step 4.5: assuming that AB is the position of the pole plate in the initial state, the distance between the two pole plates is AC, and d is L1; EF is the position of the pole plate after the wheel deflects relative to the center line of the track, and the distance d between the two pole plates after deflection is equal to L2;

step 4.6: according to the inverse trigonometric function formula, the deflection angle can be obtainedAnd BE is L1-L2, so

and 5: the correction operation is realized by a cross coupling synchronous control method; the correction method is characterized in that the first type synchronous error and the second type synchronous error are simultaneously used as input values of a position controller to participate in the adjustment of a control system; the process and its results are adjusted to maintain the rapidity and smoothness of the control system.

Technical Field

The invention relates to a control method of an automatic container terminal yard crane, in particular to a crane synchronous error measuring device and a deviation rectifying method thereof.

Background

The automated container terminal yard is comprised of a plurality of bays, each bay being configured with one or more cranes for handling and transporting operations. Because the span of the crane arranged in the storage yard is large, the two motors respectively drive the driving wheels of the cart mechanisms at the two sides, and the synchronization of the wheels at the two sides is kept by the rigidity of the bridge frame and the control system.

In the aspect of building a synchronous control system of a crane, master-slave control and parallel control are the most extensive control schemes at present, and the traditional PID is mostly adopted in a control algorithm. However, the above control schemes and control algorithms have certain defects, for master-slave control, the input signal of each slave shaft comes from the output signal of the master shaft, in the dynamic adjustment process, the input signal added to the master motor or external disturbance affects the slave motors through signal transmission and realizes the following of the master shaft, and because of the singleness of the signal transmission, the disturbance suffered by each slave motor cannot transmit and affect the running of the master motor, so the synchronism is affected and impacted; for parallel control, each shaft motor receives the same input signal, and because the whole system is not closed-loop and has no coupling effect with other shafts, when one shaft is disturbed by the outside, the other shafts do not respond to the disturbance, so that a synchronization error is generated between the motors; for the traditional PID control algorithm, the self-tuning and self-correction of parameters can not be realized in the operation process, namely, after the system generates parameter drift due to external disturbance and the like, the control algorithm can not adjust the parameters of the controller on line to adapt to the current system parameters, so that the error accumulation can not be adjusted in time, and the synchronous control is invalid.

Based on the defects of the control scheme and the control algorithm, two problems are extended: 1) the wheel slipping is caused by the sudden change of the speed of the cart mechanism during acceleration and deceleration, and the error is generated between the reading of the encoder and the actual position, so that the feedback link of the control system is in a problem, and the adjustment of the controller system is influenced; 2) the crane causes the wheels of the cart mechanism to transversely slide relative to the steel rails due to some reason, and the wheel rims and the side surfaces of the guide rails are mutually extruded and rubbed, namely the rail gnawing phenomenon is generated. The rail gnawing phenomenon can reduce the service life of the wheel, increase the maintenance cost and even cause the occurrence of safety accidents. In order to ensure the safety and the stability of the operation of the crane, a synchronous error measuring device of the crane is designed, and the two problems are solved.

Disclosure of Invention

The invention aims to provide a crane synchronous error measuring device which can more effectively and accurately measure the synchronous error; meanwhile, a deviation rectifying method based on a crane synchronous error measuring device is designed, synchronous error correction is realized through a cross-coupling synchronous control strategy, deviation in the system operation process is quickly adjusted and corrected, and the defects are overcome. Based on the voltage-capacitance characteristics of the parallel plate capacitor, the invention obtains the offset distance of the wheel center line relative to the track center line through calculation according to the conversion relation between the distance between two polar plates and the deflection angle of the wheel relative to the track center line, and the offset distance is used as the error information of the transverse sliding of the wheel. The error information is combined with the error information of the absolute value encoder to provide feedback of synchronous error values for the control system, and meanwhile, the error information and the correction process can be transmitted to the control center to provide reliable parameters for the control system and the operation of the crane.

In order to achieve the above object, the present invention provides a crane synchronization error measuring device, comprising:

the first kind of synchronous error measuring device has absolute value encoders set in the wheels of the crane; the first type of synchronous error value is obtained by subtracting the input position and the position measured by the absolute value encoder; the result of the difference is taken part in the control system adjustment as part of the input to the position controller.

Parallel plate capacitors are respectively arranged above the cart wheels on the left side and the right side of the crane; the wheels are connected with the parallel plate capacitor through a lever mechanism, and the offset distance of the two wheels relative to the central line of the track is the distance between two polar plates of the parallel plate capacitor; calculating a deflection angle according to the distance between the two polar plates and the voltage-capacitance characteristic of the parallel plate capacitor; the deflection angle is used as an additional position feedback signal of the control system, is transmitted to the input end of the controller and is used as the other part of the input of the controller to participate in the adjustment of the control system.

Most preferably, the left cart and the right cart of the crane are respectively driven by asynchronous motors, and the asynchronous motors output torque through a reduction gearbox and a power transmission mechanism thereof to drive wheels of the two carts to reciprocate along a track.

Most preferably, the first type of synchronous error measuring device (absolute value encoder) is arranged at the rear part of the motor and is rigidly connected through a rotating shaft; and the absolute value encoder calculates the distance of the driving wheel of the main motor by integrating the speed of the main motor in time.

Most preferably, the distances calculated by the absolute value encoders of the motors on the left and right sides are respectively differenced with the input positions, and the differenced result is input to one part of the controller and participates in the adjustment of the controller. In a synchronous state, distances calculated by absolute value encoders on the left side and the right side are theoretically equal; otherwise, the difference is the synchronization error.

Most preferably, in order to eliminate errors on the encoder due to wheel slip, a laser rangefinder is provided above the cart wheel to correct the encoder error; and the difference value of the current positions of the wheels measured by the laser range finder and the absolute value encoder is an error value.

Most preferably, the absolute value encoder is corrected if the error value between the laser range finder and the absolute value encoder is within a range allowing correction; if the error exceeds the allowable correction range, the crane stops and the positions of the two wheels are calibrated again.

Most preferably, the second type of synchronous error measuring device (parallel plate capacitor) is arranged right above wheels on two sides of the cart, and the distance of the central line of the wheels, which deviates from the central line of the track, is transmitted to one plate of the parallel plate capacitor through a lever mechanism so as to change the distance d between the two plates of the parallel plate capacitor; and the distance d is converted into a deflection angle alpha of the wheel deviating from the central line of the track through a formula, wherein the deflection angle alpha is the second type of synchronous error of the crane.

Most preferably, the method for calculating the second type of synchronization error comprises the following steps:

step 1: knowing the dielectric coefficient and the electrostatic force constant k of the parallel plate capacitor and the dead area S of the two polar plates;

step 2: before the crane starts, the capacitor is charged, and the charge quantity carried by the fully charged capacitor is Q;

and step 3: calculating the capacitance value according to the distance d between the two current polar plates

And 4, step 4: calculating the voltage between the two polar plates according to the current capacitance C

And 5: assuming that AB is the position of the pole plate in the initial state, the distance between the two pole plates is AC, and d is L1; EF is the position of the pole plate after the wheel deflects relative to the center line of the track, and the distance d between the two pole plates after deflection is equal to L2;

Step 6: according to the inverse trigonometric function formula, the deflection angle can be obtainedAnd BE is L1-L2, soThe deflection angle α is the second type of synchronization error.

Most preferably, the synchronization error of the second type is input as a further part of the controller, i.e. is an additional feedback signal, participating in the regulation of the controller.

The invention also provides a deviation rectifying method adopting the two error measuring devices, which is used for rectifying the synchronous error of the crane, the core of the method is a cross-coupling synchronous control strategy, and the strategy is characterized in that: the first type of synchronous error is used as a part of feedback signals and is input to a position controller to participate in the regulation of a control system; meanwhile, the second type of synchronous error is that the deflection angle corresponding to the distance of the wheel from the central line of the track is used as an additional feedback signal, so that the tracking of the signal is realized, the operation of other motors is influenced when the load of any main motor in the system changes, and the precision of synchronous control is effectively improved.

Under the cross-coupling synchronous control strategy, the deviation rectifying method of the synchronous error comprises the following steps:

step 1: according to the initial position and the target position parameters contained in the tasks distributed by the scheduling plan, the crane sequentially operates the tasks in the scheduling plan;

Step 2: the input position of the control system is the starting position (or target position) of a task, the two output positions are the traveling distances currently calculated by absolute value encoders at the rear sides of the left and right driving motors, and in addition, the difference value of the left and right encoders is a first type of synchronous error; meanwhile, the output position is fed back to the input end of the controller and is used as a part of input signals to participate in the regulation of the controller;

and step 3: the other part of signals at the input end of the controller, namely the second type synchronous error signals, are used as additional feedback signals of the controller and participate in the regulation of the controller;

and 4, step 4: the controller corrects the deviation caused by the asynchronization of the two wheels while realizing signal tracking.

And 5: and if the deviation between the absolute value encoder and the laser range finder exceeds the allowable correction range, stopping the crane, overhauling the absolute value encoder or the laser range finder, and allowing the crane to continue to operate after the positions of the two wheels of the cart are recalibrated.

Compared with the prior art, the invention has the following beneficial effects:

1. the two types of synchronous error detection devices are simple in structure, high in reliability and easy to technically realize, and in addition, the device is low in construction cost and convenient to maintain.

2. The synchronous control method of the crane adopts a cross coupling strategy, and the synchronous control under the strategy has high precision, high response speed and good control performance, and is suitable for the tense and busy working conditions of a container terminal and the like.

3. In the absolute value encoder error self-correction link, errors generated by wheel slip in the running process are corrected within an error range allowing correction, and misjudgment of a control system caused by the absolute value encoder errors is eliminated.

Drawings

FIG. 1 is a schematic view of the overall structure of a synchronous error measuring device of a crane provided by the invention;

FIG. 2 is a schematic diagram of a specific structure of a parallel plate capacitor according to the present invention;

FIG. 3 is a flow chart of an implementation of a crane position control and correction method provided by the invention;

FIG. 4 is a flow chart of encoder error self-correction provided by the present invention;

FIG. 5 is a schematic view of the deflection angle measurement provided by the present invention.

Detailed Description

The invention will be further described by the following specific examples in conjunction with the drawings, which are provided for illustration only and are not intended to limit the scope of the invention.

As shown in fig. 1, the crane synchronization error measuring device of the present invention comprises: a first type synchronous error measuring device 3 and a second type synchronous error measuring method 5. The crane comprises a cart mechanism 1, wheels 6, a running track 7, a driving motor 2 and a laser range finder 4. The first type synchronous error measuring device 3 and the second type synchronous error measuring device 5 are respectively arranged on the rear side of the driving motor 2 and the upper side of the wheel 6.

The cart mechanism 1 drives the wheels 6 on the two sides to move back and forth on the track 7 through the driving motors 2 on the left side and the right side, and the whole crane can reciprocate along the track 7. The cart mechanism 1 is a carrying platform for a first type synchronous error measuring device and a second type synchronous error measuring device.

The first type of synchronous error measuring device 3 has absolute value encoder as main component, and its position measurement principle is: the speed of the drive motor 2 is integrated with respect to time, the result of which is the displacement. The displacement is converted into the travel distance of the left wheel and the right wheel through proportion, and then the positioning of the crane is realized. The first type of synchronous error is a difference value of traveling distances of the left wheel and the right wheel, namely an error generated by asynchronous operation of the left wheel and the right wheel.

Before the crane starts, the positions of the wheels on the left side and the right side are calibrated, and the absolute value encoders are reset at the same time.

As shown in fig. 4, the left and right wheels 6 may slip due to a sudden change in speed or the like of the crane during acceleration or deceleration. When the slip occurs, the converted value of the absolute value encoder is not equal to the actual travel distance of the wheel 6, causing an error. The measurement of error is realized through laser range finder 4 that sets up on cart mechanism 1, and laser range finder and absolute value encoder are positioner, and in the hoist operation process, both measure the position of wheel 6 alone, and the measurement result is marked as X1 and X2 respectively, and error delta is | X1-X2 |.

When the error is small, namely 0< delta < a, in order to ensure the rapidity of the control system and eliminate buffeting, the error is not corrected; when a is less than or equal to delta < b, correcting the absolute value encoder, eliminating errors and ensuring the stability and stationarity of the control system; when the delta is larger than or equal to b, the error exceeds a correctable range, the crane is required to stop, and the absolute value encoder and related mechanisms thereof are overhauled.

The second type of synchronization error measuring device 5 is shown in fig. 2. The parallel plate capacitor is composed of two parallel and mutually insulated metal plates 8 and 9, the areas of the metal plates 8 and 9 are both S, and the distance between the two is d. In addition, the dielectric constant, the electrostatic force constant k, of a parallel plate capacitor is known.

Before the system operates, the capacitor is charged, and the charge quantity after charging is fixed to be Q.

Capacitance determination for parallel plate capacitors

And capacitance and voltage determination

In the formula, U is a voltage value between two plates of the parallel plate capacitor. When the distance between the two polar plates changes, the voltage U between the polar plates changes, and the distance between the two polar plates is measured according to the characteristic. Wherein, the voltage between the polar plates outputs corresponding electric signals through a conversion processing device (10).

The second type of synchronization error is defined as the yaw angle α of the centerline of the wheel 6 from the centerline of the track 7, which is measured as shown in fig. 5. Fig. 5 is a front view of a parallel plate capacitor, AB and CD are projections of two plate planes in the front view direction, respectively, where O is the midpoint of AB, L1 is the distance d between the two plates when no deflection occurs, and L1 ═ AC ═ BD. When the wheel 6 deviates from the centre line of the track 7, the distance d between the plates changes: the polar plate AB has deflection angle EF, and the deflection angle is alpha, d and DE are L2

By combining the above two determinations, the method can be obtainedNamely, under the condition that the charge quantity of the parallel plate capacitor is constant, the distance d between the two plates and the voltage U between the plates are in a linear relation.

Then calculating the deflection angle alpha of the wheels relative to the central line of the track according to the value of the distance d;

according to the formula of inverse trigonometric function, the method can be obtainedAnd BE is L1-L2, so

FIG. 3 is a flow chart of the method for controlling and rectifying the position of the crane of the present invention, and the core of the control scheme is a cross-coupled synchronous control strategy, i.e. the input of the controller is composed of two parts which jointly determine the adjustment of the controller. The specific steps of the controller regulation are as follows:

step 1: the input position 11 of the control system is a target position (start and stop position of a task) of the crane, and the output positions 15 and 20 are actual positions of the left and right cart mechanisms in current operation, respectively.

Step 2: the first type of synchronous error measuring device and the second type of synchronous error measuring device respectively measure the current positions of the left wheel 6 and the right wheel 6.

Step 2.1: the absolute value encoder 3 of the first type of synchronous error measuring device measures the positions of the left and right wheels 6 as main feedback signals 16 and 21, respectively; the parallel plate capacitors 5 of the second type of synchronous error measuring device measure the deflection angles 22 of the left and right wheels 6 relative to the central line of the track 7 as additional feedback signals 23;

Step 2.2: the two types of feedback signals 16, 21 and 23 are differed from the input position 11 to obtain a deviation signal which is used as the input signal of the left position controller 12 and the right position controller 17 to participate in the regulation of the controllers;

step 2.3: the left and right side position controllers 12 and 17 output corresponding control signals to the left and right side main motors 13 and 18 respectively after calculation, and the two main motors output certain torque to drive the left and right side transmission devices 14 and 19 after receiving the control signals, so as to drive the wheels 6 to travel for a certain distance on the track 7;

step 2.4: continuously iterating the deviation signal and the input position signal 11, adjusting the left and right position controllers 12 and 17, and continuously reducing the deviation signal; until the crane runs to the target position, the deviation signal is 0.

And step 3: when the wheel 6 slips and the like to cause an error between the measured value of the absolute value encoder and the actual position, the absolute value encoder is corrected by means of the measured value of the laser range finder. If the error exceeds the allowable correction range, the system is immediately stopped for repair and maintenance.

In conclusion, the synchronous error detection and correction method solves the problems of synchronous error detection and correction caused by two factors of inconsistent travelling distances of cart mechanisms on the left side and the right side of the crane and deflection of wheels relative to the central line of the track, and realizes the stability and rapidity adjustment of a crane control system; meanwhile, the sensor error self-correction processing process provided by the invention not only ensures the stability of system operation, but also reduces the possibility of system failure.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.